A gas sensor

Abstract

The present invention relates to a gas sensor, comprising a sensor base body, a sensing element and a protective cover. The sensor base body has a sensing element accommodation channel; the sensing element has a gas detection end; the protective cover has an opening, an air inlet, an air outlet and an accommodation cavity, and the opening, the air inlet and the air outlet are all communicated with the accommodation cavity; the gas detection end of the sensing element passes through the accommodation channel of the sensor base body and extends into the accommodation cavity of the protective cover from the opening of the protective cover, and the sensor base body and the protective cover form a first air inlet cavity and a second air inlet cavity; the protective cover is connected to the sensor base body through the opening. The protective cover of the sensor of the present invention has a simple structure and a simple production process compared with the prior art. The effect of double protection is achieved by using a single protective cover, or a three-layer protection effect is achieved by adding an additional protective cover around it. It not only has stronger functions but also is conducive to production and popularization.

Description

Technical Field

[0001] The present invention relates to the field of sensors, and particularly to a gas sensor. Background Art

[0002] A gas sensor is a device that converts information such as the composition and concentration of a gas into information that can be utilized by personnel, instruments, computers, etc. For example, an oxygen sensor is applied in an engine management system, installed in the exhaust system of an internal combustion engine, used to sense the concentration of oxygen in the exhaust gas, so as to achieve the control of pollutant emissions.

[0003] The oxygen sensor is extremely important for an internal combustion engine. It can control the fuel injection amount according to the detected oxygen content in the exhaust gas in the exhaust pipe. If the oxygen content is high, the fuel injection amount is increased; if the oxygen content is low, the fuel injection amount is decreased. If the oxygen sensor is damaged, the data transmitted to the electronic control unit will be inaccurate, thus affecting the exhaust emissions of the internal combustion engine, which will lead to fuel waste, unqualified exhaust purification and environmental pollution, etc.

[0004] However, such oxygen sensors for internal combustion engines are basically made of ceramic materials, and this ceramic material is extremely sensitive to strong temperature fluctuations, and such strong temperature fluctuations are very likely to cause the sensor to be inaccurate or fail.

[0005] During the hot operation stage of the vehicle, water vapor formed by engine combustion condenses on the surfaces of the exhaust device and the sensor, and water droplets are released from the condensed water film. Then, the water droplets are entrained by the gas flow and guided by the gas flow to the sensing element, and water droplets are very likely to be generated. These water droplets will impact on the ceramic sensing element of the high-temperature sensor, resulting in cracks or micro-cracks in the ceramic sensing element, and these cracks or micro-cracks will cause the failure of the sensor function.

[0006] To solve this problem, Patent CN102346179A introduces a double protective cover that can effectively avoid water impact. However, in the actual use process, there are still extremely extreme situations, and the problem that the high-temperature ceramic sensing element is impacted by water and generates cracks still occurs. Especially with the increasingly strict emission regulations, in order to meet the automotive exhaust emission regulations, it is required that the oxygen sensor enters the working state at the beginning to reduce the emission of harmful exhaust gas in the initial stage. However, at this time, the condensed water in the exhaust pipe has not been heated and volatilized at all, which will further increase the risk of the high-temperature ceramic sensing element being impacted by water.

[0007] In the prior art, there are also protective covers for sensors with relatively complex structures. However, in the processing of this protective cover, the structural formation of multiple parts needs to be considered, resulting in a situation where both the part cost and the production cost of this technical solution are relatively high, which is not conducive to extensive promotion and popularization.

[0008] Therefore, it is urgent to propose a new technical solution to solve the above problems. Summary of the Invention

[0009] To solve the above problems, the present invention proposes a new implementation method, that is, a method of using a single-layer protective cover to achieve a double protective cover, which saves part materials and reduces the processing difficulty. The specific technical solution is as follows:

[0010] A gas sensor includes a sensor housing, a sensing element, and a protective cover.

[0011] Furthermore, the sensor housing has a sensing element receiving channel.

[0012] Furthermore, the sensing element has a gas detection end.

[0013] Furthermore, the protective cover has an opening, an air inlet, an air outlet, and a receiving cavity, and the opening, the air inlet, and the air outlet are all communicated with the receiving cavity.

[0014] Furthermore, the gas detection end of the sensing element passes through the receiving channel of the sensor housing and extends into the receiving cavity of the protective cover from the opening of the protective cover.

[0015] Furthermore, the sensor housing and the protective cover form a first air inlet cavity and a second air inlet cavity.

[0016] Furthermore, the protective cover is connected to the sensor housing through the opening.

[0017] Furthermore, in the above technical solution, one end of the sensor housing close to the gas detection end extends into the receiving cavity of the protective cover from the opening.

[0018] Furthermore, an outer wall of the sensor housing and an inner wall of the protective cover form a first air inlet cavity, and the first air inlet cavity is close to the opening of the protective cover.

[0019] Furthermore, a gap is formed between an outer wall of the sensor housing close to the gas detection end and an inner wall of the protective cover, and the gap forms an air inlet channel. The width of the gap is not greater than 0.8 mm. With a tiny air inlet gap, water droplets will be adhered to the wall of the air inlet channel, effectively blocking the entry of water droplets.

[0020] Furthermore, an end face of one end of the sensor housing close to the gas detection end and an inner wall of the protective cover form a second air inlet cavity.

[0021] Furthermore, the first air inlet cavity, the air inlet channel, and the second air inlet cavity are sequentially communicated in the receiving cavity of the protective cover.

[0022] Furthermore, the first air inlet cavity and the second air inlet cavity are coaxially arranged.

[0023] Further, the inner diameter of the cavity of the first intake cavity is greater than the inner diameter of the cavity of the second intake cavity.

[0024] Further, the bottom of the cavity of the first intake cavity is connected to the top of the cavity of the second intake cavity through a bottom ring.

[0025] Further, the bottom ring includes a ring surface and a central through hole provided on the ring surface. The inner diameter of the central through hole is the same as the inner diameter of the second intake cavity, and the outer diameter of the ring surface is the same as the inner diameter of the first intake cavity.

[0026] Further, the end surface of one end of the sensor seat body close to the gas detection end forms a second intake channel with the surface of the bottom ring.

[0027] Further, the second intake channel is the gap formed between the end surface and the surface of the bottom ring. The width of the gap is not greater than 0.8 mm. With such a small intake gap, water droplets will be adhered to the wall of the intake channel, effectively blocking the entry of water droplets.

[0028] Further, the geometric shape of the bottom ring is the same as the geometric shape of one end of the sensor seat body close to the gas detection end.

[0029] Further, the gas detection end of the sensing element extends out of the sensor seat body and is accommodated in the second intake cavity, and there is a gap between the gas detection end and the bottom of the cavity of the second intake cavity.

[0030] Further, the intake port is communicated with the first intake cavity, and one or more intake ports are arranged along the radial direction of the first intake cavity.

[0031] Further, the outlet port is communicated with the second intake cavity, and the outlet port is opened at the bottom of the cavity of the second intake cavity.

[0032] Further, a waterproof structure is further included, and the waterproof structure is accommodated in the accommodation cavity of the protective cover.

[0033] Further, the waterproof structure includes a first waterproof structure.

[0034] Further, the waterproof structure is arranged in the first intake cavity and / or the intake channel.

[0035] Further, the first waterproof structure is arranged in the first intake cavity.

[0036] Further, the first waterproof structure has a water blocking protrusion. The water blocking protrusion surrounds the outside of the sensor seat body, and the water blocking protrusion is arranged corresponding to the intake port. Water droplets entering from the intake port will be blocked by the water blocking protrusion and bounce back.

[0037] Furthermore, there is a gap between the water blocking protrusion and the side wall of the protective cover, and the maximum width of the gap is 1.5 mm.

[0038] Furthermore, the waterproof structure further includes a second waterproof structure, which is an air intake passage. Water vapor enters the first air intake cavity from the air intake port. When flowing through the air intake passage, the water vapor flows along the inner wall of the protective cover into the second air intake cavity. Due to the tiny air intake gap, water droplets will be adhered to the wall of the air intake passage, effectively blocking the entry of water droplets.

[0039] Compared with the prior art, the present invention also has one or more of the following beneficial effects:

[0040] 1. The sensor of the present invention realizes the function of double protection by using a protective cover. The protective cover conducts the water entering the protective cover twice through the upper and lower air intake cavities, thus replacing the double protective cover in the prior art. This technical solution saves processing materials, reduces processing procedures, reduces the number of parts, makes the product lightweight, and maintains its original functionality.

[0041] 2. The sensor of the present invention can not only achieve double protection with a single layer, but also add an additional protective cover outside the protective cover, that is, double layers achieve triple protection. Compared with the prior art, this technical solution is more concise and effective, and the processing difficulty of the product is greatly reduced.

[0042] 3. The structure of the protective cover of the present invention is simple, and the design of the air intake port facilitates the entry of exhaust gas. If the sensor is installed in the exhaust pipe, the air intake port is at the edge of the exhaust gas flow. The exhaust gas flow velocity in this area is low, and the air intake ports are arranged axially and evenly distributed directly facing the gas flow direction. The exhaust gas can directly enter. And for some air intake ports that are blocked by themselves and are in an area with relatively high pressure, it is also beneficial for the exhaust gas to enter the protective cover.

[0043] 4. The protective cover of the sensor of the present invention is provided with an air outlet, which is in the central area of the exhaust gas flow and has a high flow velocity. At the same time, the opening direction of the air outlet is perpendicular to the exhaust gas flow direction. According to Bernoulli's principle, a negative pressure is formed at the air outlet, which is beneficial for gas exchange. Therefore, the design of the air outlet further ensures its functionality.

[0044] 5. The protective cover of the sensor of the present invention is used in combination with the waterproof structure, enhancing its waterproof performance. When water droplets enter the air intake port with the air flow, due to inertia, most of the water droplets will bounce back, and a part of them will flow into the first air intake cavity, and then flow through the bottom to the second waterproof structure. After being guided by the second waterproof structure, they enter the second air intake cavity. Due to the guiding effect of the second waterproof structure, the flow trajectory of the water droplets is along the inner wall of the second air intake cavity, which greatly reduces the risk of water droplets directly hitting the sensing element. Brief Description of the Drawings

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0046] Figure 1 Structural schematic diagram of the sensor according to the present invention;

[0047] Figure 2 Structural schematic diagram of the sensor according to the present invention after removing the protective cover;

[0048] Figure 3 Three-dimensional structural schematic diagram of the protective cover of the sensor according to the present invention;

[0049] Figure 4 Three-dimensional structural schematic diagram of the protective cover of the sensor according to the present invention from another angle;

[0050] Figure 5 Structural disassembly schematic diagram of the protective cover of the sensor according to the present invention;

[0051] Figure 6 Longitudinal sectional structural schematic diagram of the sensor according to the present invention;

[0052] Figure 7 For Figure 6 Partial enlarged view of the first waterproof structure in;

[0053] Figure 8 For Figure 6 Partial enlarged view of the second waterproof structure in;

[0054] Figure 9 Longitudinal sectional structural schematic diagram of the sensor according to the present invention in another embodiment;

[0055] Figure 10 Longitudinal sectional structural schematic diagram of the sensor according to the present invention in another embodiment;

[0056] Figure 11 For Figure 10 Partial enlarged view of the second waterproof structure in.

[0057] Wherein: 1 - sensing element, 11 - gas detection end,

[0058] 2 - protective cover, 21 - opening, 22 - accommodation cavity, 23 - air inlet, 24 - air outlet,

[0059] 3 - First intake cavity, 4 - Second intake cavity, 5 - Intake passage, 51 - Second intake passage,

[0060] 6 - Bottom ring, 61 - Toroidal surface, 62 - Central through - hole,

[0061] 7 - Waterproof structure; 71 - First waterproof structure, 711 - Water - blocking protrusion, 72 - Second waterproof structure,

[0062] 8 - Sensor base, 81 - End of the base. Detailed implementation mode

[0063] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation of the present invention.

[0064] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0065] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Embodiment

[0066] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0067] Embodiment 1:

[0068] A measurement sensor with a three - layer protective cover in one implementation. The three - layer protective cover includes a central protective tube sleeved on the gas detection end of the sensing element and a double - layer protective tube sleeved on the central protective tube, for a total of three layers:

[0069] The central protection tube has an opening and an inner cavity communicating with the opening. The sensing element extends into the inner cavity from the opening and has a gap with the inner wall of the inner cavity. The inner wall of the inner cavity has air-permeable holes, and a circle of the air-permeable holes is evenly distributed along the radial direction of the inner cavity;

[0070] The double protection tube includes an inner tube and an outer tube concentrically arranged with the inner tube. The inner tube has an opening and a receiving cavity communicating with the opening. The central protection tube extends into the receiving cavity from the opening. The inner diameter of the receiving cavity is larger than the inner diameter of the central protection tube. Air-permeable holes are formed on the inner wall of the receiving cavity, and a circle of the air-permeable holes is evenly distributed along the radial direction of the receiving cavity. And the air-permeable holes are arranged in a staggered manner with the air-permeable holes on the central protection tube. A central end hole is formed on the tube end of the part of the inner tube close to the gas detection end of the sensing element;

[0071] The outer tube is sleeved on the inner tube, and a tube bottom is connected to the tube end of the outer tube close to the gas detection end of the sensing element. The tube bottom extends outward from the outer wall of the inner tube along the radial direction of the inner tube and is connected to the tube end of the outer tube. A circle of air-permeable holes is evenly arranged on the tube bottom along its radial direction.

[0072] When the sensor is placed in the exhaust pipe, a narrowed cross-section part will be formed in the exhaust pipe. The acceleration of the exhaust gas in the area of the central end hole on the inner tube and the generation of a negative pressure in this area are caused by the narrowing of the cross-section; at the same time, in the exhaust gas flow direction, an overpressure is established through the air-permeable holes in the tube bottom of the outer tube in front of the protruding end of the inner tube. The pressure drop formed in this way, together with the pressure fluctuation of the exhaust gas, is responsible for the flow of the exhaust gas in the protection tube.

[0073] Part of the exhaust gas flows in through the air-permeable holes on the tube bottom of the outer tube, flows through the annular gap between the outer tube and the inner tube, so as to enter the annular gap between the inner tube and the central protection tube through the air-permeable holes on the inner tube. In this annular gap, the exhaust gas flows in the flow direction opposite to the flow direction in the annular gap between the outer tube and the inner tube and enters the inner space of the central protection tube through the air-permeable holes in the central protection tube. A strong exhaust gas eddy around the gas detection end of the sensing element is formed in the gas chamber by the contour edge formed by the air-permeable holes in the central protection tube together with the pulsating influence of the exhaust gas, thereby enabling the exhaust gas to be exchanged fast enough.

[0074] The outflow of the exhaust gas from the inner space of the central protection tube is realized through another part of the air-permeable holes and through the end holes of the inner tube. Here, the central protection holes reduce the heat loss of the sensing element caused by convection and radiation in such a way that the predetermined working temperature of the sensing element is maintained under all working conditions.

[0075] This solution can effectively solve the problem of water droplet impact on the sensing element. At the same time, the sensor protective cover has relatively more parts, which increases the processing difficulty of the product and also requires relatively more materials and costs.

[0076] Embodiment 2:

[0077] Please refer to Figures 1 - 11 , the present invention provides a gas sensor, including a sensor base 8, a sensing element 1, and a protective cover 2.

[0078] In one embodiment, the sensor base 8 has a sensing element receiving channel, and the sensing element 1 has a gas detection end 11.

[0079] The protective cover 2 has an opening 21, an air inlet 23, an air outlet 24, and a receiving cavity 22. The opening 21, the air inlet 23, and the air outlet 24 are all communicated with the receiving cavity 22, as Figures 3 - 5 shown:

[0080] In one embodiment, the protective cover 2 has a reduced diameter in the middle, which is realized by a bottom ring 6. That is, there are two coaxial upper and lower cavities in the receiving cavity of the protective cover 2, and the inner diameter of the upper cavity is larger than that of the lower cavity.

[0081] The gas detection end 11 of the sensing element 1 passes through the receiving channel of the sensor base 8 and extends into the receiving cavity 22 of the protective cover 2 from the opening 21 of the protective cover 2.

[0082] The sensor base 8 and the protective cover form a first intake cavity 3 and a second intake cavity 4;

[0083] The protective cover 2 is connected to the sensor base 8 through the opening 21, as Figure 1 , 6 shown.

[0084] In one embodiment, one end of the sensor base 8 close to the gas detection end 11 (i.e., the end 81 of the base) extends into the receiving cavity 22 of the protective cover 2 from the opening 21, and the opening 21 is connected to the outer wall of the sensor base 8.

[0085] In one embodiment, the outer wall of the sensor base 8 and the inner wall of the protective cover 2 form a first intake cavity 3, and the first intake cavity 3 is close to the opening 21 of the protective cover 2; the first intake cavity 3 is communicated with the air inlet 23, and the exhaust gas flow enters the first intake cavity 3 from the air inlet 23.

[0086] In one embodiment, a gap is formed between the outer wall of the sensor seat body 8 near the gas detection end 11 and the inner wall of the protective cover 2, and the gap forms an intake channel 5 for communicating the first intake chamber 3 and the second intake chamber 4, thereby forming a gas flow path.

[0087] In one embodiment, the width of the gap is not greater than 0.8 mm.

[0088] In one embodiment, a second intake chamber 4 is formed between the end face of the sensor seat body 8 near the gas detection end 11 and the inner wall of the protective cover 2. The tail gas flow enters the first intake chamber 3 from the intake port 23, then flows through the intake channel 5, and then flows to the second intake chamber 4 to complete the gas flow.

[0089] The first intake chamber 3, the intake channel 5, and the second intake chamber 4 are sequentially communicated within the accommodation chamber 22 of the protective cover 2 to form a gas flow path.

[0090] The first intake chamber 3 and the second intake chamber 4 are coaxially arranged.

[0091] The inner diameter of the cavity of the first intake chamber 3 is larger than the inner diameter of the cavity of the second intake chamber 4.

[0092] The bottom of the cavity of the first intake chamber 3 is connected to the top of the cavity of the second intake chamber 4 through a bottom ring 6.

[0093] The bottom ring 6 includes a ring surface 61 and a central through hole 62 provided on the ring surface 61. The inner diameter of the central through hole 62 is the same as the inner diameter of the second intake chamber 4, and the outer diameter of the ring surface 61 is the same as the inner diameter of the first intake chamber 3.

[0094] In one embodiment, the bottom ring 6 can be arranged horizontally.

[0095] In another embodiment, the bottom ring 6 can be arranged obliquely, and the height of the end of the ring surface 61 connected to the first intake chamber 3 is higher than the height of the end connected to the second intake chamber 4.

[0096] A second intake channel 51 is formed between the end face of the sensor seat body 8 near the gas detection end 11 and the surface of the bottom ring 6, that is, a second intake channel 51 is formed between the end face of the end 81 of the seat body and the surface of the bottom ring 6.

[0097] The second intake channel 51 is the gap formed between the end face and the surface of the bottom ring 6, that is, the gap formed between the end face of the end 81 of the seat body and the surface of the bottom ring 6.

[0098] In one embodiment, the width of the gap is not greater than 0.8 mm.

[0099] The geometric shape of the bottom ring 6 is consistent with the geometric shape of one end of the sensor housing 8 close to the gas detection end 11.

[0100] In one embodiment, the geometric shape of the bottom ring 6 can be circular, polygonal, etc.

[0101] The gas detection end 11 of the sensing element 1 extends out of the sensor housing 8 and is accommodated in the second air inlet cavity 4, and there is a gap between the gas detection end 11 and the cavity bottom of the second air inlet cavity 4, and this gap can prevent the water flowing down from the gas passage from contacting the gas detection end 11 of the sensing element 1.

[0102] The air inlet 23 is communicated with the first air inlet cavity 3, and one or more air inlets 23 are arranged along the radial direction of the first air inlet cavity 3; in the present invention, the sensor is installed in the automobile exhaust pipe, and the air inlet 23 is arranged near the installation thread end. Since it is at the edge of the tail gas flow, the tail gas flow velocity in this area is low. The air inlets 23 are arranged in an axial uniform distribution. For the air inlets 23 directly facing the gas flow direction, the tail gas can directly enter. And for some air inlets 23 blocked by themselves and in a region with relatively high pressure, it is also beneficial for the tail gas to enter the protective cover. Because the air inlet needs to increase the power for gas entry, the design of the air inlet in the present invention meets the functional requirements of the sensor.

[0103] The air outlet 24 is communicated with the second air inlet cavity 4, and the air outlet 24 is opened at the cavity bottom of the second air inlet cavity 4. The air outlet 24 of the sensor in the present invention is in the central region of the tail gas flow with a high flow velocity. At the same time, the opening direction of the air outlet 24 is perpendicular to the tail gas flow direction. According to Bernoulli's principle, a negative pressure is formed at the air outlet 24, which is beneficial to gas exchange.

[0104] The sensor of the present invention further includes a waterproof structure 7, and the waterproof structure 7 is accommodated in the accommodation cavity 22 of the protective cover 2.

[0105] The waterproof structure 7 includes a first waterproof structure 71 and a second waterproof structure 72.

[0106] The waterproof structure 7 is arranged in the first air inlet cavity 3 and / or the air inlet passage 5 and the second air inlet passage 51.

[0107] In one embodiment, the first waterproof structure 71 is arranged in the first air inlet cavity 3.

[0108] The first waterproof structure 71 has a water blocking protrusion 711, the water blocking protrusion 711 surrounds the outside of the sensor housing 8, and the water blocking protrusion 711 is arranged corresponding to the air inlet 23.

[0109] There is a gap between the water-blocking protrusion 711 and the side wall of the protective cover 2. The maximum width of the gap is 1.5 mm, and the gap is the assembly gap of the product.

[0110] In one embodiment, as Figure 6 , 7 , the water-blocking protrusion 711 of the first waterproof structure 71 is a circle of small protrusions provided corresponding to the air inlet 23. The small protrusions protrude from the sensor base 8. The end face of the small protrusions facing the air inlet 23 is a combined surface of a plane and an arc surface. The plane is located above the arc surface. The plane and the arc surface are connected along the tangent direction of the arc surface to form the entire end face. When the tail gas flow with water droplets enters the air inlet 23, part of the water droplets are rebounded by the plane, and the other part flows along the plane. After the water flow is diverted by the arc surface, the water droplets are diverted and slide down to the second waterproof structure at the lowest point of the arc surface.

[0111] In one embodiment, as Figures 9 - 11 , the water-blocking protrusion 711 of the first waterproof structure 71 is a circle of small protrusions provided corresponding to the air inlet 23. The small protrusions protrude from the sensor base 8. The end face of the small protrusions facing the air inlet 23 is a plane. Right below the plane is the second waterproof structure 72. When water droplets enter the protective cover 2 from the air inlet 23, they slide down onto the second waterproof structure 72 after being diverted by the plane. Since the high temperature inside the sensor is sufficient to evaporate the water, the water droplets adhering to the second waterproof structure 72 are vaporized to form water vapor, and the water vapor flows out of the protective cover through the air outlet 24.

[0112] In one embodiment, the second waterproof structure 72 can be replaced by the air inlet passage 5 and the second air inlet passage 51. The water vapor enters the first air inlet cavity 3 from the air inlet 23. When flowing through the air inlet passage 5 and the second air inlet passage 51, the water vapor flows along the inner wall of the protective cover 2 into the second air inlet cavity 4, and then flows out of the protective cover 2 through the air outlet 24. Correspondingly, at this time, the air inlet passage 5 and the second air inlet passage 51 play a waterproof role. Therefore, it can be understood that the air inlet passage 5 and the second air inlet passage 51 are a waterproof structure of this product.

[0113] In one embodiment, the bottom ring 6 can be inclined. The height of the end of the ring surface 61 connected to the first air inlet cavity 3 is higher than the height of the end connected to the second air inlet cavity 4. In this case, it can be understood that the air inlet passage 5 and the second air inlet passage 51 are another form of the second waterproof structure 72, and the inclined air inlet passage is more conducive to the flow of water.

[0114] In one embodiment, referring to FIGS. 9 and 10, the second waterproof structure 72 can be disposed around the outer periphery of the end 81 of the sensor base 8, or can be disposed below the sensor base 8:

[0115] When the second waterproof structure 72 is arranged around the end 81 of the base body, referring to Figure 6 、 9 , there is a gap between the protective cover 2 and the end 81 of the base body;

[0116] When the second waterproof structure 72 is arranged below the sensor base body 8, referring to Figure 10 、 11 , not only is there a gap between the outer wall of the end 81 of the base body and the protective cover 2, but also there is a gap between the end face of the end 81 of the base body and the protective cover 2.

[0117] Embodiment 3:

[0118] A concentric shell can also be added to the periphery of the protective cover 2 of the sensor of the present invention. Water inlet holes are arranged on the concentric shell. The water inlet holes are communicated with the outside to receive the tail gas flow. When the tail gas flow enters the concentric shell through the water inlet holes, part of the moisture is blocked, and then it enters the first intake cavity 3 through the air inlet 23 on the protective cover 2, then enters the second intake cavity 4 through the intake channel 5 and the second intake channel 51, and finally is discharged from the air outlet 24. In this way, the double-layer protective cover can achieve the effect of a triple-layer protective cover.

[0119] According to the above Embodiment 2 and Embodiment 3, the first waterproof structure 71 and the second waterproof structure 72 of the sensor of the present invention can be combined in any one of the implementation manners, and all can play a role in preventing the hidden danger of the sensing element being impacted by water.

[0120] In summary, the sensor of the present invention realizes the function of a double-layer protective cover with a single-layer protective cover. Further, compared with the prior art, the protective cover of the sensor has a simple structure, the production process is simplified, which is beneficial to the production and popularization.

[0121] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0122] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications and variations to the above embodiments within the scope of the present invention.

Claims

1. A gas sensor, characterized in that: it includes a sensor housing (8), a sensing element (1) and a protective cover (2), the sensor housing (8) has a sensing element accommodation channel; the sensing element (1) has a gas detection end (11); the protective cover (2) has an opening (21), an air inlet (23), an air outlet (24) and an accommodation cavity (22), and the opening (21), the air inlet (23) and the air outlet (24) are all communicated with the accommodation cavity (22); the gas detection end (11) of the sensing element (1) passes through the accommodation channel of the sensor housing (8) and extends into the accommodation cavity (22) of the protective cover (2) from the opening (21) of the protective cover (2), the sensor housing (8) and the protective cover form a first air inlet cavity (3) and a second air inlet cavity (4); the protective cover (2) is connected to the sensor housing (8) through the opening (21); one end of the sensor housing (8) close to the gas detection end (11) extends into the accommodation cavity (22) of the protective cover (2) from the opening (21), the outer wall of the sensor housing (8) and the inner wall of the protective cover (2) form a first air inlet cavity (3), and the first air inlet cavity (3) is close to the opening (21) of the protective cover (2); a gap is formed between the outer wall of the sensor housing (8) close to the gas detection end (11) and the inner wall of the protective cover (2), and the gap forms an air inlet channel (5), and the width of the gap is not greater than 0.8 mm; the end face of one end of the sensor housing (8) close to the gas detection end (11) and the inner wall of the protective cover (2) form a second air inlet cavity (4); the first air inlet cavity (3), the air inlet channel (5) and the second air inlet cavity (4) are sequentially communicated in the accommodation cavity (22) of the protective cover (2); the first air inlet cavity (3) and the second air inlet cavity (4) are coaxially arranged, the inner diameter of the cavity of the first air inlet cavity (3) is greater than the inner diameter of the cavity of the second air inlet cavity (4), the bottom of the cavity of the first air inlet cavity (3) is connected to the top of the cavity of the second air inlet cavity (4) through a bottom ring (6), the bottom ring (6) includes a ring surface (61) and a central through hole (62) provided on the ring surface (61), the inner diameter of the central through hole (62) is the same as the inner diameter of the second air inlet cavity (4), and the outer diameter of the ring surface (61) is the same as the inner diameter of the first air inlet cavity (3); the end face of one end of the sensor housing (8) close to the gas detection end (11) and the surface of the bottom ring (6) form a second air inlet channel (51), the second air inlet channel (51) is a second gap formed between the end face and the surface of the bottom ring (6), and the width of the second gap is not greater than 0.8 mm.

2. The gas sensor according to claim 1, characterized in that: the geometric shape of the bottom ring (6) is the same as the geometric shape of one end of the sensor housing (8) close to the gas detection end (11).

3. The gas sensor according to claim 1, characterized in that: The gas detection end (11) of the sensing element (1) extends out of the sensor housing (8) and is accommodated in the second air inlet chamber (4), and there is a gap between the gas detection end (11) and the bottom of the cavity of the second air inlet chamber (4).

4. The gas sensor according to claim 1, characterized in that: the air inlet (23) is communicated with the first air inlet chamber (3), and one or more air inlets (23) are arranged along the radial direction of the first air inlet chamber (3); the air outlet (24) is communicated with the second air inlet chamber (4), and the air outlet (24) is opened at the bottom of the cavity of the second air inlet chamber (4).

5. The gas sensor according to claim 1, characterized in that: it further includes a waterproof structure (7), the waterproof structure (7) is accommodated in the accommodation cavity (22) of the protective cover (2), the waterproof structure (7) includes a first waterproof structure (71), the waterproof structure (7) is arranged in the first air inlet chamber (3) and / or the air inlet passage (5).

6. The gas sensor according to claim 5, characterized in that: the first waterproof structure (71) is arranged in the first air inlet chamber (3), the first waterproof structure (71) has a water blocking protrusion (711), the water blocking protrusion (711) surrounds the outside of the sensor housing (8), and the water blocking protrusion (711) is arranged corresponding to the air inlet (23), there is a third gap between the water blocking protrusion (711) and the side wall of the protective cover (2), and the maximum width of the third gap is 1.5 mm.

7. The gas sensor according to claim 5, characterized in that: the waterproof structure (7) further includes a second waterproof structure (72), the second waterproof structure (72) is the air inlet passage (5), water vapor enters the first air inlet chamber (3) from the air inlet (23), and when flowing through the air inlet passage (5), the water vapor flows along the inner wall of the protective cover (2) into the second air inlet chamber (4), and then flows out of the protective cover (2) from the air outlet (24).

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