An oil fume sensor

Abstract

This invention provides an oil fume sensor, relating to the field of oil fume detection technology. Installed on the oil fume flow path of a range hood, it includes a transmitting unit, a receiving unit, and a housing. The housing has an air inlet and an air outlet, forming an oil fume detection area between them. The effective detection area of ​​the receiving unit and the light-emitting area of ​​the transmitting unit intersect within the oil fume detection area. The transmitting unit includes a light emitter and a first optical adjustment control for focusing the light emitted by the light emitter onto the intersection area, the first optical adjustment control being located on the light output side of the light emitter. The receiving unit includes a photoelectric conversion element and a second optical adjustment control, the second optical adjustment control being located on the light input side of the photoelectric conversion element. The first and second sealed cavities are physically isolated, and a gradually expanding air duct forms a low-pressure zone at the optical detection channel, forming a dual protection mechanism. It can efficiently and accurately measure oil fume concentration, has a simple structure, and low production cost.

Description

Technical Field

[0001] This invention relates to the field of oil fume detection technology, and specifically to an oil fume sensor. Background Technology

[0002] During the operation of a range hood, the fume sensor plays a crucial role in real-time monitoring of fume concentration and ensuring the efficient operation of the range hood. Its detection accuracy and stability directly affect the user experience. Currently, fume sensors based on the principle of light scattering are widely used due to their rapid response and wide detection range; however, existing technologies still face many unresolved issues in practical applications.

[0003] On the one hand, the core detection area of ​​existing oil fume sensors is not clearly defined, resulting in insufficient interaction between oil fumes and light, leading to poor detection performance. Light scattering is dispersed, and the oil fumes flow disorderly within the detection space, making the contact between oil fume particles and light insufficient and unstable. This directly results in a weak scattered light signal, and the signal strength is not strongly correlated with the oil fume concentration. Especially when detecting low-concentration oil fumes, problems such as low recognition accuracy and large errors easily occur, making it difficult to meet the needs of precise control.

[0004] On the other hand, existing technologies, in order to cover dispersed detection areas, have to set up multiple sets of optical elements and complex calibration structures, resulting in numerous sensor components and structural redundancy. For example, some sensors need to fix multiple sets of transmitting and receiving lenses with independent brackets, and each set of components must be individually optically calibrated before being assembled with the housing in multiple dimensions. This not only increases the number and types of components, but also makes the assembly process cumbersome and the process complex, which is not conducive to large-scale production, and also increases production and maintenance costs.

[0005] Furthermore, existing sensors suffer from low component integration; the transmitting and receiving units often contain independent light-emitting elements, photosensitive elements, and additional fixing components, further exacerbating structural complexity. These issues make it difficult for existing fume sensors to achieve structural simplification and improved production efficiency while maintaining detection accuracy.

[0006] Therefore, there is an urgent need for an oil fume sensor that can accurately measure the concentration of oil fumes, has a simplified structure, and is easy to assemble, in order to overcome the shortcomings of existing technologies. Summary of the Invention

[0007] The purpose of this invention is to provide an oil fume sensor to solve the problems existing in the prior art, which can efficiently and accurately measure the concentration of oil fumes, has a simple structure, and low production cost.

[0008] To achieve the above objectives, the present invention provides the following solution: an oil fume sensor is provided, which is installed on the oil fume circulation path of a range hood, and includes a transmitting unit, a receiving unit, and a housing;

[0009] The outer casing is provided with an air inlet and an air outlet, and an oil fume detection area is formed between the air inlet and the air outlet; and the effective detection area of ​​the receiving unit and the light emission area of ​​the transmitting unit have an intersection area in the oil fume detection area.

[0010] The emitting unit includes a light emitter and a first optical adjustment control for focusing the light emitted by the light emitter onto the intersection region, the first optical adjustment control being located on the light output side of the light emitter;

[0011] The receiving unit includes a photoelectric converter and a second optical adjustment control, the second optical adjustment control being located on the light input side of the photoelectric converter.

[0012] As one implementation, the cross-sectional area of ​​the airflow at the air inlet is smaller than that at the airflow outlet; a gradually expanding air duct is formed between the air inlet and the air outlet, and the cross-sectional area of ​​the gradually expanding air duct gradually increases along the airflow direction.

[0013] In one embodiment, the first optical detection channel of the transmitting unit and the second optical detection channel of the receiving unit both intersect with the expansion section of the gradually expanding air duct.

[0014] As one embodiment, the first optical adjustment control is a first optical lens; a first sealing light-transmitting element is provided on the side of the first optical lens facing the oil fume detection area, and the first sealing light-transmitting element is sealed to the inner wall of the outer shell.

[0015] In one embodiment, the first sealing light-transmitting element and the outer shell together form a first sealed cavity, and the light emitter and the first optical lens are disposed in the first sealed cavity.

[0016] As one embodiment, the second optical adjustment control is a second optical lens, and a second sealing light-transmitting element is provided on the side of the second optical lens facing the oil fume detection area. The second sealing light-transmitting element is sealed and connected to the inner wall of the housing.

[0017] In one embodiment, the second sealing light-transmitting element and the outer shell together form a second sealing cavity, and the photoelectric conversion element and the second optical lens are disposed in the second sealing cavity.

[0018] In one embodiment, the transmitting unit and the receiving unit are arranged in a V-shape, and the angle between the optical axis of the transmitting unit and the optical axis of the receiving unit is between 130° and 160°.

[0019] As one embodiment, the air inlet of the outer casing is provided with a foreign object interception device, which includes at least two ribs.

[0020] As one embodiment, an oil-repellent groove is provided above the air inlet, and the oil-repellent groove is arranged around the edge of the air inlet.

[0021] The present invention achieves the following technical effects compared to the prior art:

[0022] 1. The intersection area of ​​this invention serves as the overlapping portion of the light-emitting area of ​​the transmitting unit, the effective detection area of ​​the receiving unit, and the oil fume detection area, thereby accurately defining the core detection area. This invention uses a first optical adjustment control to concentrate light across the intersection area, while simultaneously utilizing the airflow from the air inlet and outlet to ensure that oil fume particles flow orderly through this area, guaranteeing more sufficient contact between the oil fume and the light and a more stable effect. This dual design of "light source focusing + airflow guidance" makes the correlation between the intensity of scattered light and the concentration of oil fume more significant, greatly improving detection sensitivity, especially for low-concentration oil fume, where the recognition accuracy is significantly superior to existing technologies.

[0023] Meanwhile, the spatial layout of the intersection area indirectly simplifies the structure and assembly process. Existing technologies require multiple sets of optical elements and complex calibration structures to cover dispersed detection areas, resulting in a large number of parts; while this application, through the precise positioning of the intersection area, allows the transmitting and receiving units to be directly assembled at a preset angle (such as the optical axis angle), without the need for additional calibration components, reducing the number of parts and lowering the assembly complexity.

[0024] Furthermore, the present invention adopts an integrated structural design to reduce the number of components. The transmitting unit directly integrates the light emitter and the first optical adjustment control, and the receiving unit integrates the photoelectric conversion component and the second optical adjustment control, eliminating the need for additional fixing brackets or independent calibration modules. This simplifies the assembly process, reduces the complexity of the process, and is conducive to large-scale production.

[0025] Other technical solutions of the present invention have also achieved the following technical effects:

[0026] 2. When the turbine fan is running, the air pressure generated by its rotation creates a directional airflow inside the sensor. Under the influence of this pressure difference, oil fumes enter the oil fume detection area from the inlet and then flow through a gradually expanding air duct that widens from the inlet to the outlet. Because the cross-sectional area of ​​the expanding air duct gradually increases along the airflow direction, according to the Venturi effect, the airflow velocity within the duct decreases as the cross-section expands, causing a change in the pressure distribution within the expanding air duct: relatively low-pressure areas are formed at the first optical detection channel of the transmitting unit and the second optical detection channel of the receiving unit. This effectively prevents oil fumes from diffusing into the sensor. Driven by the airflow, the oil fumes are directly discharged from the outlet along the expanding air duct, providing excellent protection against oil fume pollution. This simplifies the structure, maintains the cleanliness of the optical channels over a long period, ensures the stability of light transmission and reception, and thus extends the sensor's lifespan.

[0027] 3. The sealed structure of the first and second optical windows completely isolates the light emitter and photoelectric converter from the oil fume detection area. The first / second sealed cavities physically isolate the oil fume from the optical components, preventing direct contact between the oil fume and the optical elements, thus avoiding oil contamination on the surfaces of the light emitter, the first optical lens, the photoelectric converter, and the second optical lens. Combined with the relatively low-pressure area formed by the gradually expanding air duct at the first and second optical detection channels, the oil fume is quickly discharged along the air duct under the propulsion of the airflow, reducing the probability of oil contamination on the outer surfaces of the first and second optical windows. This dual protection mechanism effectively prevents oil fume particles from contacting the surface of the optical components. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the overall internal structure of the oil fume sensor of the present invention;

[0030] Figure 2 This is a schematic diagram showing dimensions A and B of the oil fume sensor of the present invention;

[0031] Figure 3 This is a schematic diagram of the gradually expanding air duct structure of the present invention;

[0032] Figure 4 This is a multi-view structural diagram of the oil fume sensor housing of the present invention;

[0033] Figure 5 This is a schematic diagram of the explosion of the oil fume sensor of the present invention;

[0034] Figure 6 This is a schematic diagram of the assembly of the oil fume sensor of the present invention.

[0035] The components are as follows: 1. Outer shell; 2. Air inlet; 3. Air outlet; 4. Intersection area; 5. Light emitter; 6. Photoelectric conversion component; 7. Gradually expanding air duct; 8. First optical detection channel; 9. Second optical detection channel; 10. First optical lens; 11. Second optical lens; 12. First optical window; 13. Second optical window; 14. First sealing cavity; 15. Second sealing cavity; 16. Infrared emission range; 17. Receiving area; 18. First extinction cavity; 19. Second extinction cavity; 20. Foreign object interception device; 21. Oil vent; 22. Oil leakage port; 23. Bottom shell; 24. PCB board; 25. Volute panel; 26. Volute air inlet. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] This invention provides an oil fume sensor, which is installed on the oil fume circulation path of a range hood. The oil fume sensor includes a transmitting unit, a receiving unit, and a housing 1. The housing 1 has an air inlet 2 and an air outlet 3, forming an oil fume detection area between the air inlet 2 and the air outlet 3. The effective detection area of ​​the receiving unit and the light-emitting area of ​​the transmitting unit intersect in the oil fume detection area, forming an intersection area 4. The intersection area 4 is the area where the effective detection area of ​​the receiving unit, the light-emitting area of ​​the transmitting unit, and the oil fume detection area all intersect. The transmitting unit includes a light emitter 5 and a first optical adjustment control. The first optical adjustment control is located on the light-emitting side of the light emitter 5, and can collimate the light emitted by the light emitter 5 into parallel light, concentrating the light emitted by the light emitter 5 in the intersection area 4. The receiving unit includes a photoelectric conversion element 6 and a second optical adjustment control. The second optical adjustment control is located on the light-incident side of the photoelectric conversion element 6, and can converge scattered light to the photoelectric conversion element 6.

[0039] Working principle:

[0040] S1. Fume Introduction Stage: Fumes flow along the fume circulation path of the range hood and enter the interior of the outer casing 1 through the air inlet 2. Under the action of air pressure difference, the fumes are guided to the fume detection area between the air inlet 2 and the air outlet 3, forming a stable detection airflow environment to ensure that the fume particles can flow evenly through this area.

[0041] S2. Detection Light Emission and Orientation Stage: The light emitter 5 of the emitting unit is activated, emitting initial detection light (such as infrared light). The light first reaches the first optical adjustment control located on its light emission side. The first optical adjustment control, through its own structural characteristics (such as the refraction of a lens), collimates the initial light emitted by the light emitter 5 into parallel light. The collimated parallel light propagates along a specific direction and eventually concentrates on the intersection area 4 within the fume detection area. The intersection area 4 is the overlapping part of the light emission area of ​​the emitting unit, the effective detection area of ​​the receiving unit, and the fume detection area, providing a uniform and focused light source basis for subsequent detection.

[0042] S3, Oil Fume Scattering Stage: When oil fume particles flow through intersection region 4, they interact with the parallel light emitted by the emitting unit. The oil fume particles scatter the parallel light, causing some of the light rays to deviate from their original propagation direction, forming scattered light carrying information about the oil fume concentration. The setting of intersection region 4 ensures sufficient contact between the oil fume particles and the light, thereby guaranteeing the stability of the scattering effect.

[0043] S4. Scattered Light Reception and Signal Conversion Stage: The second optical modulation control of the receiving unit is located on the light incident side of the photoelectric converter 6. It can capture the scattered light from the oil fume generated in the intersection area 4, and through its own focusing characteristics (such as the focusing effect of a lens), it converges the dispersed scattered light into a concentrated beam, which is precisely guided to the photoelectric converter 6. The photoelectric converter 6 receives the converged scattered light and converts the optical signal into a corresponding electrical signal. The strength of this electrical signal is related to the concentration of oil fume particles, thereby realizing the quantitative detection of oil fume.

[0044] S5. After the airflow discharge stage, the oil fumes that have been tested are discharged from the outer casing 1 through the air outlet 3 under the propulsion of the airflow, avoiding stagnation in the testing area and ensuring the continuity and accuracy of subsequent tests.

[0045] The parallel light emission design of the transmitting unit, the scattered light convergence design of the receiving unit, and the spatial layout of the intersection area 4 of this invention together ensure the sensitivity and stability of oil fume detection; while the structural cooperation between the air inlet 2 and the air outlet 3 provides an orderly airflow environment for oil fume detection, enabling the sensor to adapt stably to the oil fume conditions of the range hood for a long time.

[0046] This invention lays a stable foundation for oil fume detection through structural design: the airflow of the air inlet 2 and the air outlet 3 cooperates to form an orderly detection environment, ensuring that the oil fume flows evenly through the detection area and reducing environmental interference; the first optical adjustment control focuses the light on the intersection area 4, which not only improves the utilization rate of the light source, but also allows the light energy to accurately cover the core detection area, providing stable and uniform benchmark conditions for subsequent detection.

[0047] Based on this, the setting of intersection region 4 allows the oil fume and light to interact fully. Combined with the convergence of scattered light by the second optical modulation control, the detection sensitivity and signal conversion accuracy are greatly improved, enabling precise quantification of oil fume concentration. This ensures that the sensor maintains stable performance during long-term use and guarantees good detection accuracy.

[0048] In one embodiment, the cross-sectional area of ​​the airflow at the air inlet 2 is smaller than that at the air outlet 3. The pressure of the oil fume movement inside the range hood comes from the range hood's turbine fan, which is located above the sensor's air outlet 3. Preferably, the axis of the sensor's air outlet 3 is parallel to the vertical axis of the range hood fan, thus creating air pressure. After the oil fume enters the oil fume detection area from the air inlet 2, the air duct gradually expands, forming a gradually expanding air duct 7, with the cross-sectional area of ​​the airflow gradually increasing. The first optical detection channel 8 of the transmitting unit and the second optical detection channel 9 of the receiving unit are both connected to the expansion section of the gradually expanding air duct 7; and the axis of the first optical detection channel 8 intersects the centerline of the gradually expanding air duct 7 at an acute angle, while the axis of the second optical detection channel 9 also intersects the centerline of the gradually expanding air duct 7 at an acute angle. Under the Venturi effect, relatively low-pressure areas (negative pressure areas) are formed at both the first optical detection channel 8 and the second optical detection channel 9, preventing oil fume from entering the sensor through the optical channels, thus achieving the effect of preventing oil fume pollution.

[0049] In this embodiment, when the turbine fan is running, the air pressure generated by its rotation will form a directional airflow inside the sensor. Under the action of the pressure difference, the oil fumes enter the oil fume detection area from the air inlet 2, and then flow through the gradually expanding air duct 7, which is "gradually expanding from the air inlet 2 to the air outlet 3". Since the cross-sectional area of ​​the gradually expanding air duct 7 gradually increases along the airflow direction, according to the Venturi effect, the airflow velocity in the air duct will decrease as the cross-section expands, resulting in a change in the pressure distribution in the gradually expanding air duct 7: a relatively low-pressure area is formed at the first optical detection channel 8 of the transmitting unit (i.e., the connecting area between the light emitter 5 and the oil fume detection area) and the second optical detection channel 9 of the receiving unit (i.e., the connecting area between the photoelectric conversion element 6 and the oil fume detection area).

[0050] The presence of this low-pressure zone effectively prevents oil fumes from diffusing into the sensor. Driven by the airflow, the oil fumes are directly discharged from the outlet 3 along the gradually expanding air duct 7, without intruding into the internal components of the transmitting or receiving unit (such as the mounting chamber of the light emitter 5 and the photoelectric converter 6) through the optical channel. This provides excellent protection against oil fume contamination, simplifies the structure, maintains the cleanliness of the optical channel over a long period, ensures the stability of light transmission and reception, and thus extends the sensor's lifespan.

[0051] In one embodiment, the light emitter 5 is an infrared LED detection light source, preferably a 940nm infrared LED. This wavelength of light has high scattering efficiency for oil fume particles and is less affected by ambient visible light, making it suitable for accurate detection of oil fume concentration. The first optical adjustment control is a first optical lens 10, which is preferably an aspherical convex lens structure. Its focal length matches the divergence angle of the light emitter 5, and it can collimate the infrared light into a parallel beam with controllable parallelism error.

[0052] A first sealed light-transmitting element is located on the side of the first optical lens 10 facing the oil fume detection area. This first sealed light-transmitting element is a first optical window 12, made of glass or transparent plastic, preferably quartz glass. The edge of the first optical window 12 forms a ring-shaped sealed connection with the inner wall of the outer casing 1. Preferably, the first optical window 12 is sealed to the inner wall of the outer casing 1 using high-temperature resistant silicone rubber sealant, ensuring no gap between the first optical window 12 and the outer casing 1. The first optical window 12 and the outer casing 1 together form a first sealed cavity 14, encapsulating the light emitter 5 and the first optical lens 10 within the first sealed cavity 14, achieving physical isolation from the external oil fume detection area and blocking the path of oil fume directly intruding into the optical element from the source.

[0053] The central axis of the first optical window 12 coincides with the optical axis of the first optical lens 10, ensuring that the parallel light collimated by the lens can pass through the first optical lens 10 without deviation and enter the oil fume detection area.

[0054] The photoelectric converter 6 is a photoelectric conversion tube, whose photosensitive surface size matches the focusing range of the second optical modulator, enabling efficient reception of scattered light signals. The second optical modulator is a second optical lens 11, which can efficiently converge the scattered light onto the photosensitive surface of the photoelectric converter 6. The second optical lens 11 can adopt a concave focusing lens structure, which can converge the scattered light rays from the oil fume particles into a concentrated beam, accurately focusing it onto the photosensitive surface of the photoelectric converter 6, thereby improving the light signal reception efficiency.

[0055] A second sealed light-transmitting element is provided on the side of the second optical lens 11 facing the oil fume detection area. This element protects the photoelectric conversion element 6 and the second optical lens 11. The second sealed light-transmitting element is a second optical window 13. The second optical window 13 uses the same material and manufacturing process as the first optical window 12, and is connected to the outer shell 1 through the same sealing structure, forming an independent second sealed cavity 15. The photoelectric conversion element 6 and the second optical lens 11 are encapsulated and protected within this cavity. The central axis of the second optical window 13 coincides with the optical axis of the second optical lens 11, and the surface of the window is parallel to the light-gathering surface of the lens, ensuring that the scattered light is transmitted through the window without significant attenuation or deflection.

[0056] The sealing structure of the first optical window 12 and the second optical window 13 completely isolates the light emitter 5 and the photoelectric converter 6 from the oil fume detection area. The first sealing cavity 14 and the second sealing cavity 15 physically isolate and prevent direct contact between oil fumes and optical components, avoiding oil stains from adhering to the surfaces of the light emitter 5, the first optical lens 10, the photoelectric converter 6, and the second optical lens 11. Combined with the relatively low-pressure area formed by the gradually expanding air duct 7 at the first optical detection channel 8 and the second optical detection channel 9, the oil fumes are quickly discharged along the air duct under the propulsion of the airflow, reducing the probability of oil stains depositing on the outer surfaces of the first optical window 12 and the second optical window 13. This dual protection mechanism effectively prevents oil fume particles from contacting the surface of the optical components.

[0057] In this embodiment, please refer to Figure 1 As shown, the infrared light emitted by the light emitter 5 of the emitting unit is collimated by the first optical lens 10 to form an infrared parallel beam with a specific spatial range, namely the infrared emission light range 16, which propagates parallel to the emission direction.

[0058] The effective detection area of ​​the receiving unit, namely the receiving area 17, is the spatial area jointly defined by the focusing range of the second optical lens 11 and the photosensitive surface of the photoelectric conversion element 6; the second optical lens 11 can capture scattered light. The intersection area 4 is the spatial portion where the infrared emission light range 16, the effective receiving area 17 of the receiving unit, and the oil fume detection area overlap. By setting the intersection area 4, on the one hand, its spatial range precisely defines the field of action of "light-oil fume-receiver", ensuring that oil fume particles flowing through the oil fume detection area must pass through this area to scatter with the infrared light, and the scattered light falls exactly into the effective detection range of the receiving unit, avoiding invalid detection of "light not being scattered by oil fume" or "scattered light not being received"; on the other hand, the size and shape of this area can be controlled by the coordinated design of the parameters of the first optical lens 10 and the second optical lens 11 (such as collimation angle and focusing angle), which can control the matching between light energy density and receiving sensitivity, reduce the energy loss of light during propagation, and improve detection accuracy.

[0059] In one embodiment, the transmitting unit and the receiving unit are arranged in a V-shaped space within the housing 1, meaning that the optical axis (transmitting axis) of the transmitting unit and the optical axis (receiving axis) of the receiving unit form an angle θ2, which is set within the range of 130°-160°. The size of the angle θ2 directly affects the overall structural dimensions of the sensor. Let product dimension A be the length of housing 1, and product dimension B be the width of housing 1; for example... Figure 2 As shown. When θ2 is less than 145°, the intersection of the transmitting and receiving axes changes, with dimension A shortening but dimension B increasing; when θ2 is greater than 145°, dimension A increases while dimension B shortens. Through adaptability testing of the range hood volute installation space, combined with the dimensions of the reserved installation positions inside the volute, when θ2 = 145°, dimensions A and B can be controlled within a preset range, perfectly matching the installation space of mainstream range hood volutes. This avoids assembly interference caused by excessive dimensions and reduces internal component layout congestion caused by excessively small dimensions.

[0060] When θ2 is preferably set to 145°, the intersection of the transmitting and receiving axes is located precisely at the center of the fume detection area. This ensures that the volume of the intersection area 4 formed by the infrared emission range 16 and the receiving area 17 is moderate, guaranteeing sufficient interaction between the fume particles and the light while avoiding energy dispersion due to an excessively large intersection area 4. Traditional sensors with a 120° angle design suffer from excessive size B, posing a risk of interference with the curved inner wall of the range hood casing and requiring additional adjustment of the mounting bracket. In contrast, this 145° angle improves the compatibility between the outer casing 1 and the pre-reserved mounting position on the casing. The 130°-160° angle range of this invention balances structural compactness and optical performance, with θ2=145° being the optimal choice. This achieves seamless installation with the range hood casing through size coordination and ensures detection accuracy through optimized scattering angle, solving the problem of "difficulty in balancing optical performance and installation compatibility" in traditional solutions.

[0061] In one embodiment, the sensor housing 1 contains two independent extinction structures: a first extinction cavity 18 and a second extinction cavity 19. Both are located outside the fume detection area and are designed to suppress residual energy of the emitted light and ambient stray light, respectively. The first extinction cavity 18, located outside the fume detection area, prevents the emitted light from returning to the fume detection area after entering it. The second extinction cavity 19 is also provided to reduce the stray light effect of fume scattering. In this embodiment, the first extinction cavity 18 is positioned on the optical path extension line of the emitting unit. This means that if the infrared emitted light is not scattered by fume particles after passing through the fume detection area, the remaining light will directly enter the first extinction cavity 18, ensuring that the remaining light can fully enter the first extinction cavity 18 without leakage. Preferably, the entrance of the first extinction cavity 18 is aligned with the light emission direction of the emitting unit (collinear with the emission axis), and the entrance size matches the cross-section of the infrared emitted light. The inner wall of the cavity (including the bottom and sides) is treated with matte black oxidation, possessing a certain light absorption property, thus reducing the reflectivity of the light entering the cavity.

[0062] The core function of the first extinction cavity 18 is to process "direct light that does not participate in scattering": most of the infrared emitted light will be scattered by oil fume particles, and the remaining direct light, if not processed, will directly illuminate the inner wall of the outer casing 1 and be reflected back to the detection area, forming "secondary stray light". Through the above structural design, after this part of the light enters the first extinction cavity 18, the energy is absorbed or dissipated, and the intensity of the light reflected back to the oil fume detection area can be effectively reduced, thereby reducing the interference of direct light reflection.

[0063] The second extinction cavity 19 is located in the non-detection direction of the receiving unit (i.e., outside the receiving area 17), mainly to suppress "non-target scattered light" (such as scattered light from oil fume particles at non-detection angles, and stray light reflected from the inner wall of the outer casing 1). The second extinction cavity 19 is located on the extension line of the receiving direction of the receiving unit, covering the direction outside the photosensitive surface of the receiving unit, and its entrance width is adapted to the focusing range of the receiving unit. Consistent with the first extinction cavity 18, the inner wall of the second extinction cavity 19 also adopts a matte black coating design. The second extinction cavity 19 effectively attenuates the intensity of non-target light through physical blocking and energy absorption, ensuring that the photoelectric conversion element 6 has sufficient response to effectively scattered light.

[0064] In one embodiment, a foreign object interception device 20 for intercepting large particles is provided at the front end of the air inlet 2 on the outer casing 1 (near the direction of oil fume inflow). The foreign object interception device 20 can intercept large particles in the oil fume from entering the sensor or blocking the air inlet 2 of the sensor. Preferably, the foreign object interception device 20 has at least two ribs, which are arranged at intervals. The number of ribs is preferably three, the spacing between the ribs is more than 2 mm, and the edges are rounded to reduce oil stains and intercept large particles from entering the sensor without affecting the air duct.

[0065] An grease trap 21 is installed above the air inlet 2. Its function is to prevent the accumulation of oil fumes from affecting the air inlet 2. When oil mist in the fumes condenses at the edge of the air inlet 2, the grease trap 21 can guide the oil to the trap for temporary storage, preventing the oil from directly blocking the flow section of the air inlet 2. When the oil temporarily stored in the grease trap 21 reaches a certain amount, it will flow along the slope of the trap to the oil guiding slope area of ​​the outer shell 1 under the push of gravity and subsequent airflow, preventing long-term accumulation and formation of grease stains. The air inlet 2 is irregularly shaped, and the air outlet 3 is rectangular. Of course, the specific shapes of the air inlet 2 and the air outlet 3 can be adaptively adjusted according to the actual use.

[0066] In this embodiment, the lower end face of the outer casing 1 that contacts the mounting surface is designed with an oil guiding slope θ1, which is preferably between 10° and 45°; θ1 is preferably 30° to prevent the accumulation of oil fumes and the formation of oil droplets. In this solution, the oil will flow along the slope to the sheet metal of the range hood, eliminating the risk of oil dripping. This slope extends from below the air inlet 2 to the center of the bottom of the outer casing 1, and the surface of the slope is also treated with an oleophobic coating. Its function is to guide the oil adhering to the inside of the sensor (including the foreign object interception device 20, the oleophobic groove 21, and the inner wall) to a designated area: when the oil flows along the slope under the action of gravity, it will converge to the oil drain 22 opened at the bottom of the outer casing 1; the oil drain 22 is preferably a circular through hole, and the oil drain 22 is connected to the main oil exhaust pipe of the range hood. The present invention intercepts large particles through foreign object interception device 20 to avoid blockage of air inlet 2 and gradually expanding air duct 7; the oil condensate groove 21 works in conjunction with the oil guide slope (θ1=30°) to guide most of the oil to the oil drain 22, reducing the amount of oil deposited on the inner wall of the outer shell 1.

[0067] In one embodiment, the structural support assembly of the sensor includes a housing 1 and a bottom shell 23; the housing 1 has pre-drilled mounting slots for a first optical window 12 and a second optical window 13; the bottom shell 23 is fixedly connected to the housing 1 by bolts, and a sealing rubber ring is provided at the contact point between the bottom shell 23 and the housing 1 to protect the internal components from corrosion by oil fumes and moisture. Except for the air inlet 2 and the air outlet 3, the sensor detection area is a sealed structure.

[0068] The sensor package also includes a PCB board 24, with a light emitter 5 (infrared LED) and a photoelectric converter 6 soldered onto the PCB board 24. Both the light emitter 5 and the photoelectric converter 6 are soldered onto the PCB board 24. The first optical window 12 and the second optical window 13 are respectively embedded in the corresponding mounting slots of the outer casing 1 and fixed with high-temperature resistant silicone rubber sealant (which mates with the sealant groove of the outer casing 1). The central axes of the first optical window 12 and the second optical window 13 are aligned with the centers of the light emitter 5 and the photoelectric converter 6 on the PCB board 24 (coaxiality error ≤ 0.5mm) to ensure no optical path offset. The outer casing 1 and the bottom casing 23 form a closed space with screws and a sealing ring, isolating the core components such as the PCB board 24, the light emitter 5, and the photoelectric converter 6 from the external oil fume environment. The light path is only connected to the oil fume detection area through the first optical window 12 and the second optical window 13.

[0069] In one embodiment, such as Figure 6 As shown, the sensor is installed on the volute panel 25 of the range hood. Preferably, the sensor as a whole is fixed to the preset mounting position on the volute panel 25 of the range hood through the mounting holes of the bottom shell 23 by bolts. The sensor is installed below the air inlet 26 of the volute.

[0070] The sensor duct axis (i.e., the center line connecting the air inlet 2 and the air outlet 3) is completely aligned with the mainstream movement direction of the oil fumes inside the range hood. Preferably, the pressure of the oil fume movement inside the range hood comes from the range hood turbine fan, which is located above the sensor air outlet 3. The axis of the sensor air outlet 3 is parallel to the vertical axis of the range hood fan, thereby creating air pressure.

[0071] When the fumes are drawn in through the air inlet 26 of the volute, they form a spiral upward airflow along the arc-shaped guide surface of the inner wall of the volute. The axis of the sensor duct is aligned with the tangential direction of this airflow, allowing the fumes to enter the fumes detection area of ​​the sensor with minimal resistance, ensuring that the concentration of fumes entering the detection area is consistent with the actual concentration inside the volute.

[0072] In this embodiment, the range hood turbine fan is located directly above the sensor outlet 3, and the axis of the sensor outlet 3 is parallel to the vertical axis of the turbine fan (i.e., the fan's rotation center axis). The negative pressure field generated by the turbine fan directly acts on the sensor duct: when the fan rotates, a stable pressure gradient is formed at the outlet 3. The air pressure at the outlet 3 is lower than that at the inlet 2. This pressure gradient drives the fumes to flow in from the sensor inlet 2, pass through the detection area, and then be discharged from the outlet 3, ultimately being drawn into the main duct of the volute by the fan. Furthermore, in addition to being installed on the volute panel 25 of the range hood volute, this invention can also be applied to other fume paths.

[0073] Work methods:

[0074] S1. Sensor Installation and Airflow Environment Setup:

[0075] The sensor is fixed to the preset mounting position on the volute panel 25 of the range hood via the bottom shell 23, specifically below the air inlet 26 of the volute. The sensor air duct axis (the center line connecting the air inlet 2 and the air outlet 3) coincides with the mainstream movement direction of the oil fumes inside the range hood, reducing airflow resistance. The turbine fan is located above the air outlet 3, and the pressure gradient generated by the fan rotation forms a directional airflow driving force inside the sensor.

[0076] S2. Fume Introduction and Pretreatment:

[0077] When the range hood is running, the fumes flow along the main path. The fumes first flow through the foreign object interception device 20 at the front end of the air inlet 2. The three ribs of this device (spaced 2mm apart, with rounded edges) intercept large particles of foreign objects (such as food residue) with a diameter of ≥2mm, so as to avoid clogging the air duct.

[0078] The oil condensation groove 21 on the upper edge of the air inlet 2 guides the oil condensation at the edge into the groove for temporary storage, and then flows along the slope of the groove to the oil guiding slope area of ​​the outer shell 1 (θ1=30°), preventing the oil from blocking the air inlet 2;

[0079] Driven by the pressure of the turbine fan, the fumes enter the sensor from the air inlet 2. Because the cross-sectional area of ​​the air inlet 2 is smaller than that of the air outlet 3, the airflow enters the gradually expanding air duct 7 and flows along the expansion direction, forming a stable and orderly detection airflow environment.

[0080] S3. Construction of optical detection path:

[0081] The transmitting and receiving units are arranged in a V-shape (angle θ2 = 145°) to form a precise optical path, specifically including:

[0082] Parallel light emission: The 940nm infrared LED (light emitter 5) on the PCB board 24 emits infrared light, which is collimated into a parallel beam by the first optical lens 10. The parallel light enters the oil fume detection area through the first optical window 12 to ensure that the light energy is concentrated.

[0083] Receiving range limitation: The second optical lens 11 of the receiving unit forms a receiving area 17, which intersects with the infrared emission range 16 of the transmitting unit within the oil fume detection area to form an intersection area 4; this intersection area 4 is the core working field of "light-oil fume-receiving", ensuring that oil fume particles must pass through this area to be effectively scattered with the light, and the scattered light falls exactly into the receiving range.

[0084] S4. Fume Scattering and Signal Conversion:

[0085] When the oil fume flows through the intersection area 4, the oil fume particles are scattered with the infrared parallel light, forming scattered light carrying concentration information. The scattering angle matches the detection range of the receiving unit. The direct light that does not participate in the scattering enters the first extinction cavity 18 (with a matte black inner wall), where the energy is absorbed and cannot be reflected back to the detection area. Non-target scattered light (such as scattered light outside the detection angle) is intercepted and absorbed by the second extinction cavity 19, ensuring that the receiving unit fully responds to the effective scattered light.

[0086] The effective scattered light enters the receiving unit through the second optical window 13 (which is sealed with the outer shell 1 to form a second sealed cavity 15), and is focused by the second optical lens 11 onto the photosensitive surface of the photoelectric converter 6. The photoelectric converter 6 converts the light signal into an electrical signal that is positively correlated with the oil fume concentration, thus completing the quantitative detection.

[0087] S5. Synergistic effect of pollution prevention and airflow exhaust:

[0088] During the testing process, due to the Venturi effect, the gradually expanding air duct 7 forms a relatively low-pressure area at the first optical detection channel 8 and the second optical detection channel 9. The oil fumes flow along the air duct under the push of the airflow, reducing the deposition on the outer surface of the optical window.

[0089] The first sealed cavity 14 and the second sealed cavity 15 are sealed to the outer shell 1 through optical window components (high temperature resistant silicone rubber sealant), which physically isolates the internal optical components (light emitter 5, photoelectric conversion component 6, lens, etc.) from oil fumes, preventing oil stains from directly intruding;

[0090] Oil stains adhering to the inner wall of the sensor, the interception device, and the grease trap 21 flow to the bottom oil drain 22 under the action of the oil guide slope (θ1=30°), and finally flow into the main oil drain pipe of the range hood to prevent oil dripping and accumulation; the oil fumes that have completed the detection are discharged from the sensor through the air outlet 3 and are sucked into the main air duct of the range hood by the turbine fan to avoid lingering in the detection area and to ensure the continuity of subsequent detection.

[0091] This working method achieves high-precision detection of oil fume concentration through a complete process design of "installation and adaptation - airflow regulation - optical detection - anti-fouling coordination - signal output". It can also operate stably for a long time in high oil and high temperature environments, meeting the working conditions of range hoods. It has a simple structure and low cost, and can accurately measure oil fume concentration while also taking into account good oil prevention performance.

[0092] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0093] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A fume sensor, installed on the fume flow path of a range hood, characterized in that: It includes a transmitting unit, a receiving unit and a housing (1); the housing (1) is provided with an air inlet (2) and an air outlet (3), and an oil fume detection area is formed between the air inlet (2) and the air outlet (3); and the effective detection area of ​​the receiving unit and the light emission area of ​​the transmitting unit have an intersection area (4) in the oil fume detection area. The emitting unit includes a light emitter (5) and a first optical adjustment control for focusing the light emitted by the light emitter (5) onto the intersection region (4), the first optical adjustment control being located on the light output side of the light emitter (5); The receiving unit includes a photoelectric converter (6) and a second optical adjustment control, the second optical adjustment control being located on the light input side of the photoelectric converter (6); The cross-sectional area of ​​the airflow inlet (2) is smaller than that of the airflow outlet (3); a gradually expanding air duct (7) is formed between the air inlet (2) and the air outlet (3), and the cross-sectional area of ​​the gradually expanding air duct (7) gradually increases along the airflow direction. The transmitting unit and the receiving unit are arranged in a V-shape; The first optical detection channel (8) of the transmitting unit and the second optical detection channel (9) of the receiving unit both intersect with the expansion section of the gradually expanding air duct (7); The angle between the optical axis of the transmitting unit and the optical axis of the receiving unit is between 145° and 160°; The sensor housing (1) is provided with a first extinction cavity (18) and a second extinction cavity (19); the first extinction cavity (18) is located on the optical path extension line of the transmitting unit; the second extinction cavity (19) is located on the receiving direction extension line of the receiving unit. The air inlet (2) of the outer shell (1) is provided with a foreign object interception device (20), which includes at least two ribs.

2. The oil fume sensor according to claim 1, characterized in that, The first optical adjustment control includes a first optical lens (10); the first optical lens (10) is provided with a first sealing light-transmitting element on the side facing the oil fume detection area, and the first sealing light-transmitting element is sealed to the inner wall of the outer shell (1).

3. The oil fume sensor according to claim 2, characterized in that, The first sealing light-transmitting element and the outer shell (1) together form the first sealing cavity (14), and the light emitter (5) and the first optical lens (10) are disposed in the first sealing cavity (14).

4. The oil fume sensor according to claim 1, characterized in that, The second optical adjustment control includes a second optical lens (11), and the second optical lens (11) is provided with a second sealing light-transmitting element on the side facing the oil fume detection area. The second sealing light-transmitting element is sealed and connected to the inner wall of the outer shell (1).

5. The oil fume sensor according to claim 4, characterized in that, The second sealing light-transmitting element and the outer shell (1) together form the second sealing cavity (15), and the photoelectric conversion element (6) and the second optical lens (11) are disposed in the second sealing cavity (15).

6. The oil fume sensor according to claim 1, characterized in that, An oil vent (21) is provided above the air inlet (2), and the oil vent (21) is arranged around the edge of the air inlet (2).

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