Vehicle-mounted gas leakage detection system

Abstract

The invention relates to the technical field of air pollution detection, in particular to a vehicle-mounted gas leakage detection system which comprises a main machine, a collecting cover, a gas inlet assembly and a flow guide assembly. The air inlet assembly and the flow guide assembly are arranged, the air inlet assembly is used for adaptively adjusting the air inlet amount under different vehicle speed conditions, it is guaranteed that the sufficient air inlet amount is provided for equipment in a main engine for detection at the low vehicle speed, and turbulent flow is avoided through the air inlet assembly at the high vehicle speed; the representativeness and the accuracy of the sampled gas are ensured through laminar flow; after air which is not interfered by turbulence is collected, laminar flow is converted into turbulence through the flow guide assembly, so that the uniformity of the concentration of fuel gas in the air is ensured, and the accuracy of a detection result is further ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of air pollution detection, and particularly to a vehicle-mounted gas leakage detection system. Background Art

[0002] As a key equipment for dynamic monitoring of urban gas pipelines, the technical evolution of vehicle-mounted gas leakage detection systems has always focused on improving the gas sampling accuracy in mobile scenarios. Currently, the mainstream technical solution is to install a gas collection device at the front end of the vehicle, and by means of the natural wind pressure generated when the vehicle is moving, guide the air sample into the vehicle-mounted analyzer for detection. This solution can, to a certain extent, achieve continuous monitoring of the gas concentration along the road, especially being able to detect methane emission points hundreds of meters away from the vehicle. However, in practical applications, this technical solution exposes obvious deficiencies in working condition adaptability, specifically reflected in the following two aspects: Firstly, when the vehicle is moving at a low speed, due to the relatively low relative motion speed between the vehicle and the air, an insufficient dynamic pressure gradient cannot be formed, resulting in a significant reduction in the air flow velocity at the inlet of the gas collection device. This directly leads to an insufficient amount of gas samples collected per unit time, making it difficult to meet the detection requirements for trace gas leakage. More seriously, the engine waste heat and environmental pollutants during low-speed driving may cause local gas interference, further affecting the authenticity of the detection signal.

[0003] Secondly, when the vehicle is moving at a high speed, the intense interaction between the vehicle and the air will cause complex flow field distortion. The turbulent vortices formed around the vehicle body will result in a highly non-uniform spatial distribution of the leaked gas, causing significant differences in the gas concentration values at different positions at the same moment. At the same time, the pressure pulsation and aerosol deposition effect generated by the high-speed air flow in the gas collection pipeline will further cause abnormal molecular diffusion and time delay in the transmission process of the gas sample, ultimately resulting in a systematic deviation between the detection data and the actual leakage state.

[0004] Therefore, a vehicle-mounted gas leakage detection system is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a vehicle-mounted gas leakage detection system, which solves the problem that the intake air volume is insufficient when the vehicle is moving at a low speed and turbulence is easily formed when the vehicle is moving at a high speed, thereby affecting the detection accuracy. By controlling the opening size and angle of the intake area through the intake component, the intake air volume is increased at low vehicle speeds to compensate for the insufficient natural wind speed, and the size of the intake area is reduced at high vehicle speeds. The air flow is accelerated through the Venturi effect, sacrificing part of the intake air volume to maintain laminar flow, thereby ensuring the accuracy of the detection result.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: A vehicle-mounted gas leakage detection system includes a main unit, and also includes a collection hood, an air intake assembly, and a flow guiding assembly. The flow guiding assembly is connected to the main unit, the collection hood is connected to the flow guiding assembly, and the air intake assembly is connected to the front end of the collection hood. The main unit adjusts the size of the air intake opening of the collection hood through the air intake assembly according to the vehicle speed, and promotes the gas to flow in a spiral manner before entering the main unit through the flow guiding assembly.

[0007] Through the above solution, the control of the air intake volume is achieved by using the air intake assembly. When the vehicle is running at a low speed, the air intake assembly expands the air intake area, thereby compensating for the problem of insufficient air intake caused by the lack of natural wind speed, and further ensuring the detection effect of gas in this area range at low vehicle speeds. When the vehicle is running at a high speed, the air intake assembly adaptively adjusts the air intake area according to the Reynolds coefficient, thereby avoiding the formation of turbulence. At the same time, the air flow is accelerated through the Venturi effect, and a small part of the air intake volume is sacrificed to maintain laminar flow, so that the device can adapt to the detection accuracy when the vehicle is running at a high speed, thus improving the overall detection efficiency.

[0008] Preferably, the collection hood is in a funnel shape, and its cross-sectional area gradually decreases from the air intake assembly to the flow guiding assembly.

[0009] Through the above solution, the gas is gradually pressurized and accelerated during the process of entering the flow guiding assembly from the collection hood. The gas mixing speed is accelerated by the pressurization method, so that the gas distribution in the air is more uniform, and the detection accuracy is improved.

[0010] Preferably, a first chute is provided on the front side of the collection hood, and slide rails are provided on both the upper and lower sides of the collection hood. The air intake assembly includes an electric telescopic rod, a sliding plate, a movable shaft, a movable plate, and a first slider. The electric telescopic rod is connected to the collection hood, the sliding plate is connected to the slide rail, the movable shaft is connected to the sliding plate, the movable plate is connected to the movable shaft, and the first slider is connected to the side of the movable plate away from the movable shaft.

[0011] Through the above solution, the host sends a signal according to the vehicle speed, so that the electric telescopic rod controls the front and rear positions of the skateboard according to the vehicle speed, and the skateboard controls the opening size of the front end of the collection hood through the front and rear movement of the movable shaft. When the vehicle is driving at a low speed, the electric telescopic rod controls the movable shaft to move forward through the skateboard, so that the two movable plates on the same movable shaft approach each other, so that the opening size of the front end of the collection hood gradually becomes larger, thereby increasing the intake area and compensating for the insufficient intake air volume caused by the insufficient natural wind speed; when the vehicle is driving at a high speed, the electric telescopic rod controls the movable shaft to move backward through the skateboard, so that the two movable plates on the same movable shaft move away from each other, so that the opening size of the front end of the collection hood gradually becomes smaller. On the one hand, by reducing the intake area, the Reynolds coefficient is reduced, so as to avoid the formation of turbulence, and thus the uneven gas distribution caused by the turbulence near the intake opening can be avoided, thereby ensuring the accuracy and representativeness of the sampling. On the other hand, the Venturi effect is formed by the movable plate, and the dynamic pressure difference generated by the vehicle speed is used to actively suck in the leaked gas, improve the local concentration, and thus improve the accuracy of the gas detection.

[0012] Preferably, two movable plates are connected to each of the movable shafts, and the two movable plates on the same movable shaft are in a "V" shape.

[0013] Through the above solution, the inclination degree of the movable plate is controlled by the position of the movable shaft, so as to adaptively adjust the opening size of the front end of the collection hood. In addition, the inclined movable plate can also avoid the situation of turbulence caused by the direct impact of the crosswind to a certain extent, thereby ensuring the stability of the air flow entering the collection hood.

[0014] Preferably, a second chute and a third chute are also provided on the front side of the collection hood; a straight plate is connected to the rear side of the movable plate, and second sliders and third sliders are provided on the upper and lower sides of the straight plate, and the second sliders and the third sliders are respectively connected to the second chute and the third chute.

[0015] Through the above solution, through the cooperation of the second sliders, the third sliders and the second chute, the third chute, the straight plate is always kept in the front and rear directions. At the same time, the straight plate extends the throat in the Venturi pipe, further ensuring the stability of the laminar flow, so that the leaked gas diffuses stably in the laminar flow, and thus its concentration distribution is uniform, and further improving the detection accuracy.

[0016] Preferably, the diversion assembly includes a straight pipe and a bent pipe. The straight pipe is connected to the collection hood, one end of the bent pipe is connected to the straight pipe, and the other end is connected to the host. A plurality of diversion vanes are connected in the straight pipe, and the diversion vanes are spiral in the straight pipe.

[0017] Since the main tasks of the collection hood and the intake assembly are to efficiently and stably collect air samples, ensure that the incoming gas is representative, without excessive external interference, and accurately capture the original sample, it is necessary to form a stable laminar flow of the incoming air. The goal of the pipeline for transporting gas is to make the gas mix evenly, so as to ensure uniform concentration inside it. Therefore, through the above solution, when the gas enters the straight pipe from the collection hood, it is affected by the spiral-shaped guide vanes, causing the gas to transform from laminar flow to turbulent flow, thereby promoting uniform mixing of the gas, avoiding concentration stratification, and further ensuring the accuracy of the detection results.

[0018] Preferably, the overall shape of the elbow pipe is an Archimedean spiral-shaped structure, and its overall diameter gradually increases from bottom to top.

[0019] There are likely to be some particulate impurities in the outside air. To prevent these impurities from entering the main machine with the air and damaging it, through the above solution, when the gas mixed with particulate impurities flows rapidly along the spiral elbow pipe, the fluid is forced to continuously change direction. Since the mass of the particles is larger than that of the gas, their inertia is stronger, and they are more inclined to maintain their original direction of motion. While the gas molecules have a smaller mass and are more likely to turn along the flow channel. At this time, the solid particles are pushed towards the inner wall of the elbow pipe by the centrifugal force and separated from the gas. At the same time, after the solid particles impact the inner wall of the elbow pipe, they lose kinetic energy and deposit on the surface of the channel. Finally, the clean gas enters the main machine along the elbow pipe for detection; in addition, in this solution, the shape of the elbow pipe is designed with reference to the Archimedean spiral, which can ensure the smooth transition of the air flow, ensure the uniformity of the gas concentration distribution during the movement, and further ensure the accuracy of the detection results.

[0020] Preferably, a fixing block and a pulling plate are provided at the connection between the elbow pipe and the straight pipe. A limiting rod is connected to the pulling plate, and the limiting rod is slidably connected to the fixing block. A return spring is sleeved on the limiting rod, and both ends of the return spring are connected to the fixing block and the limiting rod respectively.

[0021] Through the above solution, when the vehicle stops moving, the particulate matter in the elbow pipe slides down under the influence of gravity and finally slides to the area where the pulling plate is located. At this time, by pulling the pulling plate downward, the inside of the elbow pipe is connected to the outside, so that the particulate matter in this area falls out. For the particulate matter in the elbow pipe that has not yet slid near the pulling plate, just pull the pulling plate downward and then release it. At this time, the pulling plate impacts the elbow pipe under the action of the return spring, thereby accelerating the falling of the particulate matter in the elbow pipe, and further realizing the cleaning of the particulate impurities separated in the elbow pipe.

[0022] Compared with the prior art, the beneficial effects of the present invention are: 1. A vehicle-mounted gas leakage detection system of the present invention adjusts the intake air volume adaptively under different vehicle speeds by setting an intake component and a flow guiding component. At low vehicle speeds, it ensures sufficient intake air volume to supply the devices in the main unit for detection, and at high vehicle speeds, it avoids the formation of turbulence through the intake component and ensures the representativeness and accuracy of the sampled gas through laminar flow. After collecting the air not disturbed by turbulence, the flow guiding component converts the laminar flow into turbulent flow, thereby ensuring the uniformity of the gas concentration in the air and further ensuring the accuracy of the detection result.

[0023] 2. A vehicle-mounted gas leakage detection system of the present invention changes the size of the front opening of the collection hood by setting a movable plate according to the position state of the movable plate at different vehicle speeds. At low vehicle speeds, the two movable plates on the same movable shaft move closer to each other to increase the intake area and compensate for the insufficient intake air volume caused by the lack of natural wind speed. At high vehicle speeds, the above two movable plates move in opposite directions to reduce the intake area, thereby reducing the Reynolds number and avoiding the formation of turbulence, thus ensuring the accuracy and representativeness of the sampling. On the other hand, a Venturi effect is formed by the movable plate, and the dynamic pressure difference generated by the vehicle speed is used to actively suck in the leaked gas to increase the local concentration, thereby improving the accuracy of gas detection.

[0024] 3. A vehicle-mounted gas leakage detection system of the present invention promotes the uniform mixing of gas by setting a straight pipe and a bent pipe, and uses the spiral flow guiding vanes in the straight pipe to convert the gas from laminar flow to turbulent flow, thereby avoiding concentration stratification and further ensuring the accuracy of the detection result. The gas forming turbulent flow enters the bent pipe to form a centrifugal motion, further promoting the uniform mixing of gas, and at the same time using the centrifugal force to separate the particulate impurities existing inside, thereby ensuring the purity of the detection gas and further ensuring the accuracy of the detection result. In addition, the overall shape of the bent pipe can also ensure the smooth transition of the air flow, thereby ensuring the uniformity of the gas concentration distribution during the movement and further ensuring the accuracy of the detection result. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of the installation position of the intake component of the present invention in the vehicle body; Figure 2 It is a schematic structural diagram of the relative position of the collection hood, the intake component and the flow guiding component of the present invention; Figure 3 It is a schematic structural diagram of the collection hood of the present invention; Figure 4 It is a schematic structural diagram of the intake component of the present invention; Figure 5 It is a schematic structural diagram of the movable plate and the straight plate of the present invention; Figure 6 It is a schematic structural diagram of the flow guiding component of the present invention; Figure 7 For the present invention Figure 6 An enlarged view of part A in the present invention; Figure 8 It is a flow path diagram of the gas of the present invention when passing through the intake assembly and entering the collection hood.

[0026] In the figure: 1, main machine; 2, collection hood; 3, intake assembly; 301, electric telescopic rod; 302, slide plate; 303, movable shaft; 304, movable plate; 305, slider one; 306, straight plate; 307, slider two; 308, slider three; 4, diversion assembly; 401, straight pipe; 402, elbow pipe; 403, diversion vane; 5, chute one; 6, slide rail; 7, chute two; 8, chute three; 9, fixed block; 10, pull plate; 11, limiting rod; 12, return spring. Specific embodiments

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] Please refer to Figures 1 to 8 , the present invention provides a vehicle-mounted gas leakage detection system, and the technical solution is as follows: Specifically, please refer to Figure 1 , Figure 2 and Figure 3, A vehicle-mounted gas leakage detection system, including a main unit 1. Inside the main unit 1, there is a gas analyzer for detecting gas concentration. Inside the gas analyzer, there is a gas sensor capable of detecting gas. Through this gas sensor, the methane plume characteristics (size, emission amount, concentration, ethane content, etc.) in the collected gas are measured, and through the main unit 1, risk ranking and emission quantification analysis are carried out to predict the location, flow rate, and relative risk of the leakage indication (that is, indicating whether it may come from a dangerous leakage), so as to calculate and locate the approximate area of the gas leakage through the main unit 1. It also includes a collection hood 2, an air intake component 3, and a diversion component 4. The diversion component 4 is connected to the main unit 1. The gas collected through the air intake component 3 is transported to the gas analyzer inside the main unit 1 through the diversion component 4. The collection hood 2 is connected to the diversion component 4. The collection hood 2 is funnel-shaped, and its cross-sectional area gradually decreases from the air intake component 3 to the diversion component 4, so that the gas is gradually pressurized and accelerated during the process of entering the diversion component 4 from the collection hood 2, thereby making the gas distribution in the air more uniform and improving the detection accuracy; The air intake component 3 is connected to the front end of the collection hood 2, and the air intake amount is controlled by the air intake component 3. When the vehicle is running at a low speed, the air intake area is enlarged through the air intake component 3 to increase the air intake amount. When the vehicle is running at a high speed, the formation of turbulence is suppressed through the air intake component 3, so as to ensure the quality of sampling.

[0029] As an implementation manner of the present invention, referring to Figure 2 , Figure 3 , Figure 4 and Figure 5 , on the upper and lower sides of the inner wall of the front side of the collection hood 2, there are both a first chute 5 opened. The first chute 5 is strip-shaped. On the upper and lower sides of the collection hood 2, there are both slide rails 6; The air intake component 3 includes an electric telescopic rod 301, a slide plate 302, a movable shaft 303, a movable plate 304, and a first slider 305. The electric telescopic rod 301 is connected to the collection hood 2. The slide plate 302 is connected to the slide rail 6. The movable shaft 303 is connected to the slide plate 302. The electric telescopic rod 301 automatically controls the front and rear positions of the slide plate 302 according to the vehicle speed, and the slide plate 302 controls the opening size of the front end of the collection hood 2 through the front and rear movement of the movable shaft 303. When the vehicle is running at a low speed, the electric telescopic rod 301 controls the movable shaft 303 to move forward through the slide plate 302. When the vehicle is running at a high speed, the electric telescopic rod 301 controls the movable shaft 303 to move backward through the slide plate 302; The movable plate 304 is connected to the movable shaft 303. Two movable plates 304 are connected to each movable shaft 303, and the two movable plates 304 on the same movable shaft 303 are in a "V" shape. The inclination degree of the movable plate 304 is controlled by the position of the movable shaft 303, so as to adaptively adjust the opening size at the front end of the collection hood 2. The movable plate 304 is made of aluminum alloy and its surface is anodized to make it take into account both lightweight and cavitation resistance. The first slider 305 is connected to the side of the movable plate 304 away from the movable shaft 303, and the first slider 305 is slidably connected to the first chute 5. A second chute 7 and a third chute 8 are also provided on the front side of the collection hood 2. The second chute 7 and the third chute 8 are parallel to the first chute 5 and have the same length. Their order from front to back is the first chute 5, the second chute 7, and the third chute 8. A straight plate 306 is connected to the rear side of the movable plate 304. Sliders 307 and 308 are provided on both the upper and lower sides of the straight plate 306. The sliders 307 and 308 are respectively connected to the second chute 7 and the third chute 8. The straight plate 306 is always kept in the front-rear direction by the sliders 307 and 308. The stability of the laminar flow is further ensured by the straight plate 306, thereby improving the accuracy of detection.

[0030] As an implementation manner of the present invention, referring to Figure 6 and Figure 7 , the flow guiding assembly 4 includes a straight pipe 401 and a bent pipe 402. The straight pipe 401 is connected to the collection hood 2. One end of the bent pipe 402 is connected to the straight pipe 401, and the other end is connected to the main machine 1. A plurality of flow guiding vanes 403 are connected in the straight pipe 401. The flow guiding vanes 403 are in a spiral shape in the straight pipe 401. When the gas enters the straight pipe 401 from the collection hood 2, it is affected by the spiral flow guiding vanes 403, so that the gas is transformed from laminar flow to turbulent flow, thereby promoting the uniform mixing of the gas and avoiding concentration stratification. The overall shape of the bent pipe 402 is an Archimedean spiral-shaped structure. This shape can ensure the smooth transition of the air flow, thereby ensuring the uniformity of the gas concentration distribution during the movement, and further ensuring the accuracy of the detection result. Moreover, the overall diameter of the bent pipe 402 gradually increases from bottom to top, and the centrifugal force of the gas moving in the bent pipe 402 is used to separate the particulate impurities therein, thereby ensuring the accuracy of the detection. A fixed block 9 and a pull plate 10 are provided at the connection between the elbow pipe 402 and the straight pipe 401. A through groove is provided at a position near the lower side of the pull plate 10, through which a staff member can insert a finger to conveniently pull the pull plate 10. Pulling the pull plate 10 downward can make the inside of the elbow pipe 402 communicate with the outside, so that the particulate matter in this area drops out; a limiting rod 11 is connected to the pull plate 10, and the limiting rod 11 is slidably connected to the fixed block 9. A return spring 12 is sleeved on the limiting rod 11, and both ends of the return spring 12 are connected to the fixed block 9 and the limiting rod 11 respectively. Pull the pull plate 10 downward and then release it. At this time, the pull plate 10 collides with the elbow pipe 402 under the action of the return spring 12, which can accelerate the dropping of the impurities that have not dropped, so as to realize the cleaning of the particulate matter impurities separated in the elbow pipe 402.

[0031] The specific working principle is as follows: In the technical requirements of on-vehicle gas leakage detection equipment, on the one hand, it is necessary to ensure that the collected air sample is representative, avoid uneven gas distribution caused by turbulence near the intake area, avoid gas stratification, and make it mix homogenously by force, so as to ensure the accuracy of sampling; on the other hand, it is necessary to ensure that the gas entering the detection equipment in the main unit 1 is evenly mixed. Therefore, appropriate turbulence can mix gases with different concentrations, making the gas entering the analyzer in the main unit 1 more uniform, thereby reducing the detection error, and being able to detect the area where gas leakage occurs in time, realizing the function of air pollution detection.

[0032] Therefore, in this solution, in the gas collection stage, by setting the intake assembly 3, the gas entering the collection hood 2 forms a stable laminar flow, efficiently and stably collecting air samples, ensuring that the entering gas is representative, without excessive external interference, and accurately capturing the original sample; while in the gas transportation stage, through the diversion assembly 4, the sampled gas is transformed from a stable laminar flow into a turbulent flow, thereby mixing gases with different concentrations, making the gas concentration distribution more uniform, and further reducing the detection error.

[0033] Specifically, in the gas collection stage, when the vehicle is in a low-speed driving state, the natural wind speed is insufficient, resulting in insufficient intake air volume. In order to avoid affecting the detection result, the main unit 1 sends a signal to the electric telescopic rod 301. At this time, the electric telescopic rod 301 controls the movable shaft 303 to move forward through the slide plate 302, so that the two movable plates 304 on the same movable shaft 303 approach each other, so that the opening size at the front end of the collection hood 2 gradually becomes larger, thereby increasing the intake area, and ensuring that there is enough gas entering the main unit 1 for detection, thus ensuring the reliability of the detection result when the vehicle is driving at a low speed; When the vehicle is traveling at a high speed, due to the too-fast gas flow rate at this time, the Reynolds number increases, which easily forms turbulence. Turbulence will generate vortices near the intake area and entrain external air to dilute the leaked gas, thus reducing the representativeness and accuracy of the collected gas. To avoid this situation, when the vehicle is traveling at a high speed, the main unit 1 sends a signal to the electric telescopic rod 301. At this time, the electric telescopic rod 301 controls the rearward movement of the movable shaft 303 through the slide plate 302, so that the two movable plates 304 on the same movable shaft 303 move away from each other, so that the opening size at the front end of the collection hood 2 gradually becomes smaller. On the one hand, the Reynolds number is reduced by reducing the intake area, thus avoiding the formation of turbulence. On the other hand, the Venturi effect is formed by the movable plate 304, and the leaked gas is actively sucked in by using the dynamic pressure difference generated by the vehicle speed to increase the local concentration, thereby improving the accuracy of gas detection. In the gas transportation stage, the collected gas passes through the collection hood 2 and enters the straight pipe 401 and contacts the spiral guide vanes 403. Under the action of the guide vanes 403, the gas gradually transforms from laminar flow to turbulent flow, thus promoting the uniform mixing of the gas and avoiding concentration stratification. When the mixed gas enters the elbow 402, the overall shape of the elbow 402 can also ensure the smooth transition of the air flow, thus ensuring the uniformity of the gas concentration distribution during the movement. In addition, in order to prevent particulate impurities in the gas from affecting the detection result and damaging the detection instrument, when the gas moves in the spiral elbow 402, due to the mass and inertia differences between the solid and the gas, the particulate impurities will gradually separate from the gas and deposit on the inner wall of the elbow 402, so that the clean gas enters the main unit 1 for detection, ensuring the accuracy of the detection result. After the vehicle stops moving, the particulate matter in the elbow 402 slides down under the influence of gravity to the position where the pull plate 10 is located. At this time, the staff pulls down the pull plate 10 to connect the inside of the elbow 402 with the outside, so that the impurities are discharged from the elbow 402. To prevent some impurities from not being discharged from the elbow 402 in time, the staff only needs to pull down the pull plate 10 and then release it. At this time, the pull plate 10 impacts the elbow 402 under the action of the return spring 12, thus accelerating the dropping of the particulate matter in the elbow 402. Then, the operation of pulling down the pull plate 10 is repeated, thereby realizing the cleaning of the particulate impurities separated in the elbow 402.

[0034] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A vehicle-mounted gas leakage detection system, comprising a main unit (1), characterized in that: It further includes a collection hood (2), an air intake assembly (3) and a flow guiding assembly (4). The flow guiding assembly (4) is connected to the main engine (1), the collection hood (2) is connected to the flow guiding assembly (4), and the air intake assembly (3) is connected to the front end of the collection hood (2). The main engine (1) adjusts the size of the air intake opening of the collection hood (2) through the air intake assembly (3) according to the vehicle speed, and promotes the gas to flow in a spiral manner before entering the main engine (1) through the flow guiding assembly (4).

2. The on-vehicle gas leakage detection system according to claim 1, characterized in that: The collection hood (2) is funnel-shaped, and its cross-sectional area gradually decreases from the air intake assembly (3) to the flow guiding assembly (4).

3. The on-vehicle gas leakage detection system according to claim 1, characterized in that: A first chute (5) is provided on the front side of the collection hood (2), and slide rails (6) are provided on both the upper and lower sides of the collection hood (2). The air intake assembly (3) includes an electric telescopic rod (301), a slide plate (302), a movable shaft (303), a movable plate (304) and a first slider (305). The electric telescopic rod (301) is connected to the collection hood (2), the slide plate (302) is connected to the slide rail (6), the movable shaft (303) is connected to the slide plate (302), the movable plate (304) is connected to the movable shaft (303), and the first slider (305) is connected to the side of the movable plate (304) away from the movable shaft (303).

4. The on-vehicle gas leakage detection system according to claim 3, wherein: Two movable plates (304) are connected to each movable shaft (303), and the two movable plates (304) on the same movable shaft (303) are in a "V" shape.

5. The on-vehicle gas leakage detection system according to claim 3, wherein: A second chute (7) and a third chute (8) are also provided on the front side of the collection hood (2). A straight plate (306) is connected to the rear side of the movable plate (304), and second sliders (307) and third sliders (308) are provided on both the upper and lower sides of the straight plate (306). The second sliders (307) and the third sliders (308) are respectively connected to the second chute (7) and the third chute (8).

6. The on-vehicle gas leakage detection system according to claim 1, characterized in that: The flow guiding assembly (4) includes a straight pipe (401) and a bent pipe (402). The straight pipe (401) is connected to the collection hood (2), one end of the bent pipe (402) is connected to the straight pipe (401), and the other end is connected to the main engine (1). A plurality of flow guiding vanes (403) are connected in the straight pipe (401), and the flow guiding vanes (403) are spiral in the straight pipe (401).

7. The on-vehicle gas leakage detection system according to claim 6, characterized in that: The overall shape of the bent pipe (402) is an Archimedean spiral-shaped structure, and its overall diameter gradually increases from bottom to top.

8. The on-vehicle gas leakage detection system according to claim 6, characterized in that: A fixed block (9) and a pull plate (10) are provided at the connection between the bent pipe (402) and the straight pipe (401). A limiting rod (11) is connected to the pull plate (10), the limiting rod (11) is slidably connected to the fixed block (9), a return spring (12) is sleeved on the limiting rod (11), and both ends of the return spring (12) are respectively connected to the fixed block (9) and the limiting rod (11).

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