Gas flow detection device in gas pipe and range hood

Abstract

The invention relates to a gas flow detection device in a gas pipe and a range hood, the gas flow detection device in the gas pipe comprises a detection optical fiber which is tightly attached to the outer wall of a detected gas pipe connected with a kitchen range in a spiral winding manner; the photoelectric emission module is connected with the detection optical fiber and is used for emitting pulsed light into the detection optical fiber; the photoelectric detection module is used for receiving a reflected light signal transmitted back from the detection optical fiber; the signal analysis module is in communication connection with the photoelectric detection module and is used for acquiring the flow Q of gas flowing through the gas flowing cavity in the pipe joint body by utilizing a reflected light signal returned by the photoelectric detection module; and the signal sending module is connected with the signal analysis module and used for sending the gas flow Q obtained by the signal analysis module to external equipment. Compared with the prior art, the gas flow measuring device has the advantage that the gas flow in the gas pipe can be measured without intrusive installation.

Description

Technical Field

[0001] The present invention relates to a detection device capable of detecting the gas flow rate and gas components in a gas pipe connected to a stove, and a range hood capable of being linked controlled with the stove. Background Art

[0002] Range hoods are essential appliances for daily cooking and smoke extraction. Combo products with a range hood and stove linkage function have become increasingly popular in recent years. However, existing range hood and stove linkage products have the following drawbacks:

[0003] First, these packaged products often only include the special models of certain manufacturers. Even if users choose range hoods and stoves from the same manufacturer, their choice of combinations will be limited, not to mention that some users have to choose range hoods and stoves from two different manufacturers.

[0004] Second, some products utilize infrared temperature sensors and other detection components installed on range hoods to perform non-contact temperature measurement of pots, burners, and other areas above the stove. These sensors attempt to determine the stove's open or closed status based on temperature changes. However, these infrared temperature sensors currently measure the average temperature of a large area encompassing the stovetop. The localized temperature rise at the moment of opening or closing has little impact on the results. Furthermore, the temperature measured when the pot lid is covered is easily averaged by the surrounding low-temperature area, leading to widespread misjudgment, such as accidental shutdowns and inactions. This can even cause the range hood to shut down mid-cooking, reducing the user experience. Furthermore, the temperature measurement method uses regional temperature changes to infer whether the stove is open or closed to adjust the range hood's status, which inherently lags behind the actual on / off state.

[0005] Therefore, the above-mentioned prior art needs to be further improved. Summary of the Invention

[0006] The first technical problem to be solved by the present invention is to provide a gas flow detection device capable of detecting the gas flow rate in the gas pipe connected to the stove in accordance with the above-mentioned prior art. The detection device can measure the gas flow rate inside the gas pipe without invasive installation.

[0007] The second technical problem to be solved by the present invention is to provide a range hood that can be linked controlled according to the gas flow flowing into the stove in response to the above-mentioned existing technology, and the detection of the gas flow in the gas pipe can measure the gas flow inside the gas pipe without invasive installation.

[0008] The technical solution adopted by the present invention to solve the first technical problem is: a gas flow detection device in a gas pipe, characterized by comprising:

[0009] The detection optical fiber is spirally wound and adhered to the outer wall of the gas pipe to be tested, which is connected to the cooker;

[0010] A photoelectric emission module connected to the detection optical fiber and used for emitting pulsed light into the detection optical fiber;

[0011] A photoelectric detection module for receiving a reflected light signal transmitted back from the detection optical fiber;

[0012] The signal analysis module is connected to the photoelectric detection module, and the analysis module uses the reflected light signal returned by the photoelectric detection module to obtain the Brillouin scattering frequency shift Δv B Or obtain the stress change Δε of the outer wall of the gas pipe under test caused by the internal gas flow, and finally calculate the stress change Δε according to Δv B Or Δε to obtain the gas flow rate Q flowing through the gas flow cavity in the pipe joint body;

[0013] The signal sending module is connected to the signal analysis module and is used to send the gas flow Q obtained by the signal analysis module to an external device.

[0014] As an improvement, the signal analysis module obtains the gas flow rate Q flowing through the gas flow cavity in the pipe joint body through the following steps:

[0015] Step 1: The photoelectric transmission module transmits a short pulse light signal and obtains the Brillouin scattering spectrum of the first reflected light signal returned by the photoelectric detection module;

[0016] Step 2: According to step 1, the Brillouin scattering spectrum is fitted to the first Brillouin gain spectrum curve, and the peak frequency in the first Brillouin gain spectrum curve is extracted to obtain the first Brillouin scattering frequency shift v B短 ;

[0017] Step 3: The photoelectric transmission module transmits a long pulse light signal, and obtains the Brillouin scattering spectrum of the second reflected light signal returned by the photoelectric detection module at this time;

[0018] Step 4: According to step 3, the Brillouin scattering spectrum is fitted into the second Brillouin gain spectrum curve, and the peak frequency in the second Brillouin gain spectrum curve is extracted, that is, the second Brillouin scattering frequency shift v is obtained. B长 ;

[0019] Step 5: Shift the first Brillouin scattering frequency v B短 Subtract the second Brillouin scattering frequency shift v B长 The Brillouin scattering frequency shift Δv after eliminating the temperature effect is obtained B , Δv B =v B短 -v B长

[0020] Step 6: According to the frequency shift Δv B Obtain the gas flow rate Q flowing through the gas flow cavity in the pipe joint body:

[0021] Q=K*Δv B

[0022] Wherein, K is the preset calibration constant.

[0023] As a preferred solution, the photoelectric emission module first emits a laser pulse, and then alternately emits short pulse light signals and long pulse light signals to eliminate the temperature effect. The scanning frequency range is 10.8MHz-11.2GHz, with a step of 1MHz. The wavelength of the laser pulse is 1550nm; the wavelength of the short pulse light signal is 10nm; and the wavelength of the long pulse light signal is 100nm. The short pulse light signal can locate the strain mutation point due to its high spatial resolution, thereby obtaining the first Brillouin scattering frequency shift v B短 , emits a long pulse light signal, which can be used to obtain the background temperature field due to its low spatial resolution, thereby obtaining the second Brillouin scattering frequency shift v B长 .

[0024] As another solution, in order to eliminate the influence of temperature, a reference optical fiber is also included, which is arranged parallel to the gas pipe under test and spaced apart. The reference optical fiber is also connected to the photoelectric transmission module, which can emit pulsed light into the reference optical fiber; at the same time, the reference optical fiber is also connected to the photoelectric detection module, which can also receive the reflected light signal transmitted back from the reference optical fiber.

[0025] The signal analysis module obtains the gas flow rate Q flowing through the gas flow cavity in the pipe joint body through the following steps:

[0026] Step (1) uses the reflected light signal transmitted back from the detection optical fiber to obtain the wavelength offset Δλ1 of the detection optical fiber. The wavelength offset Δλ1 of the detection optical fiber is affected by the strain and temperature of the outer wall of the gas pipe being tested:

[0027] Δλ1=K ε Δε+K T ΔT;

[0028] The wavelength offset Δλ2 of the reference fiber is obtained by using the reflected light signal transmitted back from the reference fiber. The wavelength offset Δλ2 of the reference fiber is only affected by temperature:

[0029] Δλ2=K T ΔT;

[0030] Among them, K ε is the strain sensitivity coefficient of the outer wall of the gas pipe being tested, which is a preset constant; K T is the temperature sensitivity coefficient of the outer wall of the gas pipe being tested, which is also a preset constant; ΔT is the temperature change;

[0031] Step (2): differential processing of strain signals to eliminate temperature effects:

[0032] Δλ=Δλ1-Δλ2=K ε Δε;

[0033] Step (3): Obtain the stress change Δε of the outer wall of the gas pipe under test caused by the internal gas flow:

[0034] Δε=Δλ / K ε ε;

[0035] Step (4) uses the pipe wall stress change Δε to obtain the gas flow rate Q flowing through the gas flow cavity in the pipe joint body:

[0036] Q=K1*sqrt(Δε)

[0037] Wherein, K1 is the preset calibration constant; sqrt() is the square root function.

[0038] The technical solution adopted by the present invention to solve the second technical problem is as follows: the machine body is further provided with a signal receiving module that can be matched with the signal sending module of the gas flow detection device in the gas pipe described in claim 1 or 2. When the signal receiving module receives the gas flow Q sent by the signal sending module of the gas flow detection device in the gas pipe, the gear position of the fan system is adjusted according to the gas flow Q. The specific control method is:

[0039] If the gas flow rate Q is less than Q a , judging that the current fire power of the stove is low fire power, and adjusting the gear of the fan system to low gear;

[0040] If Q is greater than or equal to Q a Less than or equal to Q b , judging that the current fire power of the stove is medium fire power, and adjusting the gear of the fan system to the medium gear;

[0041] If Q is greater than Q b , judging that the current fire power of the stove is high fire power, adjusting the gear of the fan system to high gear;

[0042] Q a , Q b is a preset constant, and Q a b .

[0043] The signal sending module and the signal receiving module are paired signal communication modules.

[0044] ​Compared with the existing technology, the advantages of the present invention are: by spirally winding the detection optical fiber on the outer wall of the gas pipe, the changes in the propagation characteristics of the thermoelastic stress wave of the pipe wall caused by the gas flow are detected, which solves the problem that traditional flow meters need to invade the pipeline or modify the valve, and realizes non-contact gas flow detection; its flow detection accuracy reaches ±5% of the range; it is compatible with metal pipes and plastic pipes, improving scene adaptability, detection accuracy and user cooking comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the installation structure of a gas flow detection device in a gas pipe according to an embodiment of the present invention.

[0046] Figure 2 Schematic diagram of the installation structure of a gas flow detection device in a gas pipe according to an embodiment of the present invention.

[0047] Figure 3 Schematic diagram of the linkage structure of a cooker and a range hood in an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0049] Example 1

[0050] The gas flow detection device in the gas pipe of this embodiment is shown in FIG. Figure 1 , which includes:

[0051] The detection optical fiber 1 is spirally wound and adhered to the outer wall of the gas pipe 2 to be tested, which is connected to the cooker;

[0052] A photoelectric emission module 3 connected to the detection optical fiber and used for emitting pulsed light into the detection optical fiber;

[0053] A photoelectric detection module 4 for receiving the reflected light signal transmitted back from the detection optical fiber;

[0054] The signal analysis module 5 is connected to the photoelectric detection module in communication. The analysis module uses the reflected light signal returned by the photoelectric detection module to obtain the changes in the propagation characteristics of the thermoelastic stress wave of the outer wall of the gas pipe under test due to the internal gas flow, and obtains the Brillouin scattering frequency shift Δv B , thereby obtaining the gas flow rate Q flowing through the gas flow cavity in the pipe joint body;

[0055] The signal sending module 6 is connected to the signal analyzing module 5 and is used to send the gas flow Q obtained by the signal analyzing module to an external device.

[0056] The signal analysis module obtains the gas flow rate Q flowing through the gas flow cavity in the pipe joint body through the following steps:

[0057] Step 1: The photoelectric transmission module transmits a short pulse light signal and obtains the Brillouin scattering spectrum of the first reflected light signal returned by the photoelectric detection module;

[0058] Step 2: According to step 1, the Brillouin scattering spectrum is fitted to the first Brillouin gain spectrum curve, and the peak frequency in the first Brillouin gain spectrum curve is extracted to obtain the first Brillouin scattering frequency shift v B短 ;

[0059] Step 3: The photoelectric transmission module transmits a long pulse light signal, and obtains the Brillouin scattering spectrum of the second reflected light signal returned by the photoelectric detection module at this time;

[0060] Step 4: According to step 3, the Brillouin scattering spectrum is fitted into the second Brillouin gain spectrum curve, and the peak frequency in the second Brillouin gain spectrum curve is extracted, that is, the second Brillouin scattering frequency shift v is obtained. B长 ;

[0061] Step 5: Shift the first Brillouin scattering frequency v B短 Subtract the second Brillouin scattering frequency shift v B长 The Brillouin scattering frequency shift Δv after eliminating the temperature effect is obtained B , Δv B =v B短 -v B长

[0062] Step 6: According to the frequency shift Δv B Obtain the gas flow rate Q flowing through the gas flow cavity in the pipe joint body:

[0063] Q=K*Δv B

[0064] Wherein, K is the preset calibration constant.

[0065] In actual operation, the photoelectric transmission module can first emit a laser pulse with a wavelength of 1550nm, and then alternately emit short pulse light signals and long pulse light signals. The short pulse light signal has a wavelength of 10nm and the long pulse light signal has a wavelength of 100nm. The scanning frequency range is 10.8MHz-11.2GHz, with a step of 1MHz. The short pulse light signal can locate the strain mutation point due to its high spatial resolution, thereby facilitating the acquisition of the first Brillouin scattering frequency shift v B短 , emits a long pulse light signal, which can be used to obtain the background temperature field due to its low spatial resolution, thereby facilitating the acquisition of the second Brillouin scattering frequency shift v B长 .

[0066] In this embodiment, the detection optical fiber uses a Bragg grating sensor, the core of which is a section of optical fiber engraved with a periodic refractive index grating. When wound around a gas pipeline, the dynamic pressure changes and heat exchange temperature changes generated by the flow of gas will cause strain on the pipe wall, causing the grating period or refractive index to change, resulting in a shift in the reflected Bragg wavelength. By demodulating the wavelength shift, the temperature, strain, or pressure changes on the pipeline wall can be inferred.

[0067] The detection mechanism of this embodiment is to directly sense the strain of the gas pipe under test by utilizing the frequency shift characteristics of Brillouin scattering, eliminating the reference optical fiber. By alternately emitting long and short pulses of light, the reflected long and short pulses are differentially processed to eliminate the ΔT-related term. This solves the complexity and reliability issues of the dual-fiber differential solution and achieves: 1) single-fiber fully distributed measurement; 2) self-compensation for temperature-strain cross-sensitivity; 3) centimeter-level positioning of the leak point; 4) strain resolution of ±2με and a temperature-induced residual error of <0.5%.

[0068] When the Brillouin scattering frequency shift Δv obtained in step 5 B If the preset threshold is exceeded, such as 50Mhz, it can be determined that the gas leaks. At this time, the signal analysis module can output the gas leak alarm signal and send it to the external device through the signal sending module, such as the range hood controlled by the stove, so that the range hood can take corresponding measures.

[0069] Example 2

[0070] The difference from the first embodiment is that it also includes a reference optical fiber 7 arranged parallel to the gas pipe 2 to be tested, and the reference optical fiber 7 is also connected to the photoelectric transmission module, which can transmit pulsed light into the reference optical fiber 7; at the same time, the reference optical fiber is also connected to the photoelectric detection module, which can also receive the reflected light signal transmitted back from the reference optical fiber. Figure 2 shown.

[0071] The signal analysis module obtains the gas flow rate Q flowing through the gas flow cavity in the pipe joint body through the following steps:

[0072] Step (1) uses the reflected light signal transmitted back from the detection optical fiber to obtain the wavelength offset Δλ1 of the detection optical fiber. The wavelength offset Δλ1 of the detection optical fiber is affected by the strain and temperature of the outer wall of the gas pipe being tested:

[0073] Δλ1=k ε Δε+K T ΔT;

[0074] The wavelength offset Δλ2 of the reference fiber is obtained by using the reflected light signal transmitted back from the reference fiber. The wavelength offset Δλ2 of the reference fiber is only affected by temperature:

[0075] Δλ2=K T ΔT;

[0076] Among them, K ε is the strain sensitivity coefficient of the outer wall of the gas pipe being tested, which is a preset constant; K T is the temperature sensitivity coefficient of the outer wall of the gas pipe being tested, which is also a preset constant; ΔT is the temperature change;

[0077] Step (2): differential processing of strain signals to eliminate temperature effects:

[0078] Δλ=Δλ1-Δλ2=K ε Δε;

[0079] Step (3): Obtain the stress change Δε of the outer wall of the gas pipe under test caused by the internal gas flow:

[0080] Δε=Δλ / K ε ε;

[0081] Step (4) uses the pipe wall stress change Δε to obtain the gas flow rate Q flowing through the gas flow cavity in the pipe joint body:

[0082] Q=K1*sqrt(Δε)

[0083] Where K1 = π·d 2 / 4·sqrt(E·d / (C·ρ g )), d is the inner diameter of the gas pipeline being measured, which is a known constant, E is the elastic modulus of the gas pipeline being measured, which is a known constant, ρ g is the gas density, which is a known constant. C is the pipe structural coefficient, which is a known constant, typically ≈ 0.032 for metal pipes. Therefore, K1 is a preset calibration constant. sqrt() is the square root function.

[0084] When the tube wall stress change Δε obtained in step (3) exceeds a threshold value such as εa (such as set to 3 times the normal maximum fluctuation amplitude), it can be determined that there is a gas leak. At this time, the signal analysis module can output a gas leak alarm signal and send it to an external device through the signal sending module, such as a range hood controlled in conjunction with the stove, so that the range hood takes corresponding measures.

[0085] The detection optical fiber in the above-mentioned gas flow detection device can be installed on the outer wall of the gas main pipe at the bottom of the stove, or on the outer walls of the left and right branch pipes.

[0086] This embodiment also provides a range hood that can be controlled in conjunction with a stove, comprising a body 101, wherein a fan system 102 is provided in the body 101. Figure 3As shown, the range hood can be linked with the stove 103 below, and the gas flow detection device in the gas pipe having the structure of any of the two embodiments described above is installed on the outer wall of the gas pipe connected to the bottom of the stove 103, one end of which is connected to the external gas pipe connector and the other end of which is connected to the inlet of the gas main connector at the bottom of the stove; the body 101 is also provided with a signal receiving module 104 that can be matched with the signal sending module 4 of the gas flow detection device in the gas pipe. When the signal receiving module receives the gas flow Q sent by the signal sending module of the gas flow detection device in the gas pipe, the gear position of the fan system is adjusted according to the gas flow Q. The specific control method is as follows:

[0087] If the gas flow rate Q is less than Q a , judging that the current fire power of the stove is low fire power, and adjusting the gear of the fan system to low gear;

[0088] If Q is greater than or equal to Q a Less than or equal to Q b , judging that the current fire power of the stove is medium fire power, and adjusting the gear of the fan system to the medium gear;

[0089] If Q is greater than Q b , judging that the current fire power of the stove is high fire power, adjusting the gear of the fan system to high gear;

[0090] Q a , Q b is a preset constant, and Q a b .

[0091] The signal sending module and the signal receiving module are paired signal communication modules.​

Claims

1. A gas flow detection device in a gas pipe, characterized in that include: The detection optical fiber is spirally wound and adhered to the outer wall of the gas pipe to be tested, which is connected to the cooker; A photoelectric emission module connected to the detection optical fiber and used for emitting pulsed light into the detection optical fiber; A photoelectric detection module for receiving a reflected light signal transmitted back from the detection optical fiber; The signal analysis module is connected to the photoelectric detection module, and the analysis module uses the reflected light signal returned by the photoelectric detection module to obtain the Brillouin scattering frequency shift Δv B Or obtain the stress change Δε of the outer wall of the gas pipe under test caused by the internal gas flow, and finally calculate the stress change Δε according to Δv B Or Δε to obtain the gas flow rate Q flowing through the gas flow cavity in the pipe joint body; The signal sending module is connected to the signal analysis module and is used to send the gas flow Q obtained by the signal analysis module to an external device.

2. The gas flow detection device in a gas pipe according to claim 1, characterized in that: The signal analysis module obtains the gas flow rate Q flowing through the gas flow cavity in the pipe joint body through the following steps: Step 1: The photoelectric transmission module transmits a short pulse light signal and obtains the Brillouin scattering spectrum of the first reflected light signal returned by the photoelectric detection module; Step 2: According to step 1, the Brillouin scattering spectrum is fitted to the first Brillouin gain spectrum curve, and the peak frequency in the first Brillouin gain spectrum curve is extracted to obtain the first Brillouin scattering frequency shift v B短 ; Step 3: The photoelectric transmission module transmits a long pulse light signal, and obtains the Brillouin scattering spectrum of the second reflected light signal returned by the photoelectric detection module at this time; Step 4: According to step 3, the Brillouin scattering spectrum is fitted into the second Brillouin gain spectrum curve, and the peak frequency in the second Brillouin gain spectrum curve is extracted, that is, the second Brillouin scattering frequency shift v is obtained. B长 ; Step 5: Shift the first Brillouin scattering frequency ν B短 Subtract the second Brillouin scattering frequency shift ν B长 The Brillouin scattering frequency shift Δv after eliminating the temperature effect is obtained B , Δv B =v B短 -v B长 Step 6: According to the frequency shift Δv B Obtain the gas flow rate Q flowing through the gas flow cavity in the pipe joint body: Q=K*Δν B Wherein, K is the preset calibration constant.

3. The gas flow detection device in a gas pipe according to claim 2, characterized in that: The photoelectric transmitting module first emits laser pulses, and then alternately emits short pulse light signals and long pulse light signals, scanning the frequency range from 10.8MHz to 11.2GHz with a step of 1MHz.

4. The gas flow detection device in a gas pipe according to claim 3, characterized in that: The laser pulse wavelength is 1550nm; the short pulse light signal wavelength is 10nm; and the long pulse light signal wavelength is 100nm.

5. The gas flow detection device in a gas pipe according to claim 1, characterized in that: It also includes a reference optical fiber that is arranged parallel to the gas pipe under test and spaced apart. The reference optical fiber is also connected to the photoelectric transmission module, which can emit pulsed light into the reference optical fiber. At the same time, the reference optical fiber is also connected to the photoelectric detection module, which can also receive the reflected light signal transmitted back from the reference optical fiber.

6. The gas flow detection device in a gas pipe according to claim 5, characterized in that: The signal analysis module obtains the gas flow rate Q flowing through the gas flow cavity in the pipe joint body through the following steps: Step (1) uses the reflected light signal transmitted back from the detection optical fiber to obtain the wavelength offset Δλ1 of the detection optical fiber. The wavelength offset Δλ1 of the detection optical fiber is affected by the strain and temperature of the outer wall of the gas pipe being tested: Δλ1=K ε No+K T ΔT; The wavelength offset Δλ2 of the reference fiber is obtained by using the reflected light signal transmitted back from the reference fiber. The wavelength offset Δλ2 of the reference fiber is only affected by temperature: Δλ2=K T ΔT; Among them, K ε is the strain sensitivity coefficient of the outer wall of the gas pipe being tested, which is a preset constant; K T is the temperature sensitivity coefficient of the outer wall of the gas pipe being tested, which is also a preset constant; ΔT is the temperature change; Step (2): differential processing of strain signals to eliminate temperature effects: Δλ=Δλ1-Δλ2=K ε No; Step (3): Obtain the stress change Δε of the outer wall of the gas pipe under test caused by the internal gas flow: No.=Dl / K ε e; Step (4) uses the pipe wall stress change Δε to obtain the gas flow rate Q flowing through the gas flow cavity in the pipe joint body: Q=K1*sqrt(Δε) Wherein, K1 is the preset calibration constant; sqrt() is the square root function.

7. A range hood comprising a body, a fan system disposed therein, characterized in that: The machine body is further provided with a signal receiving module that can be matched with the signal sending module of the gas flow detection device in the gas pipe according to any one of claims 1 to 6. When the signal receiving module receives the gas flow Q sent by the signal sending module of the gas flow detection device in the gas pipe, the gear position of the fan system is adjusted according to the gas flow Q. The specific control method is: If the gas flow rate Q is less than Q a , judging that the current fire power of the stove is low fire power, and adjusting the gear of the fan system to low gear; If Q is greater than or equal to Q a Less than or equal to Q b , judging that the current fire power of the stove is medium fire power, and adjusting the gear of the fan system to the medium gear; If Q is greater than Q b , judging that the current fire power of the stove is high fire power, adjusting the gear of the fan system to high gear; Q a , Q b is a preset constant, and Q a b .​ 8. The range hood according to claim 7, characterized in that: The signal sending module and the signal receiving module are paired signal communication modules.

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