A near backscattering vehicle-mounted particulate matter sensor and exhaust pipe

Abstract

A near backscattering vehicle-mounted particulate matter sensor is installed in an exhaust pipe for use. When detecting the concentration of particulate matter in exhaust gas, a controller controls a laser 6 to emit a laser, and the laser is transmitted to a collimating lens through an optical fiber and a laser channel. The laser passing through the collimating path is irradiated into the exhaust gas of the exhaust pipe. When particulate matter in the exhaust gas encounters the irradiation of the laser, the light beam will be scattered and diffusely reflected in all directions. A part of the scattered light beam is converged into the optical fiber through a photosensitive channel, and then the scattered light signal is received by a detector 9 and converted into an electrical signal for transmission to the controller, so as to monitor the emission of particulate matter of a diesel engine in real time. In addition, the present invention has the advantages of simple structure, accurate measurement, fast response, convenient installation and disassembly, and low cost.

Description

Technical Field

[0001] The invention relates to a sensor device, in particular to a near backscattering vehicle-mounted particle sensor for detecting automobile exhaust particles of a diesel engine. Background Art

[0002] The diesel particulate matter sensor is an important component for detecting the particulate matter content in diesel engine exhaust. It is installed on the diesel engine exhaust pipe to detect and monitor the particulate matter downstream of the DPF (Diesel Particulate Filter) in real time, realize DPF fault diagnosis and regeneration control, and make the diesel engine emissions meet regulatory requirements.

[0003] Traditional methods for detecting particulate matter concentration in diesel engine exhaust include differential pressure sensor, membrane weighing method and smoke density method. As national emission regulations on diesel engine exhaust particulate matter become more and more stringent, traditional differential pressure sensors can no longer meet the requirements due to their low sensitivity. Although the membrane weighing method has a more accurate measurement value, it is complicated to operate and has a high measurement cost. The smoke density method is generally carried out using a smoke meter, but the smoke meter is expensive, the equipment is bulky, and it cannot achieve real-time measurement on the vehicle.

[0004] Existing particulate matter sensors, such as the sensor for detecting particulate matter disclosed in Chinese patent CN212031240U, include a laser and a photoelectric converter, and the laser and the photoelectric converter are placed on the same side, using optical fiber to transmit the laser and using a reflective mirror to reflect the laser. However, in a harsh exhaust gas environment, high temperature will cause the optical fiber to melt and shrink, thereby reducing the transmission efficiency of the laser. In addition, the reflective mirror is directly exposed to the exhaust gas environment, which will cause the reflective mirror to be quickly contaminated by the exhaust gas. In addition, from the perspective of the structure of the patent design, it is also difficult to remove the mirror contamination. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a near backscattering vehicle-mounted particulate matter sensor with strong resistance to external vibration interference and small measurement error.

[0006] In order to achieve the above purpose, the technical solution adopted by this method is as follows:

[0007] A near backscattering vehicle-mounted particulate matter sensor,

[0008] It includes a probe rod body installed on the engine exhaust pipe;

[0009] The laser, collimating lens, focusing lens and detector are installed inside the probe rod body;

[0010] A laser, used for emitting laser light to a collimating lens;

[0011] The collimating lens is used to collimate the received laser, and the collimated laser is irradiated into the engine exhaust pipe and diffusely reflected on the surface of the exhaust particles;

[0012] The condenser lens is used to receive the light that is diffusely reflected from the surface of the exhaust particles and then irradiates the condenser lens, and then converges and emits it;

[0013] A detector, used for receiving the reflected light focused by the focusing lens;

[0014] The controller is connected with the laser and the detector, and is used for controlling the operation of the laser and the detector, and comparing the signal intensity of the emitted laser and the concentrated reflected light, so as to calculate the concentration of the particulate matter. Beneficial Effects

[0015] The probe rod is used to integrate and package the laser, collimating lens, focusing lens and detector. The laser emits laser to the collimating lens, and the laser emitted by the collimating lens irradiates the smoke in the large exhaust pipe. The laser irradiates the surface of the smoke particles and diffusely reflects. The diffusely reflected light is converged by the focusing lens and the converged reflected light is transmitted to the detector. The controller calculates the concentration of particulate matter in the exhaust gas based on the intensity of the reflected light.

[0016] Placing the laser and detector directly inside the sensor rod independently of the controller reduces the light loss of laser transmission and lowers the amplification factor, thereby reducing the impact of circuit noise signals on measurement accuracy. This allows the measurement range to cover more than 90% of particles, greatly improving the monotonic responsiveness of the sensor.

[0017] The laser and the detector are installed inside the front part of the probe rod body;

[0018] The rear portion of the probe rod body can be detachably mounted on the engine exhaust pipe, and the collimating lens and the focusing lens are mounted on the rear end of the probe rod body;

[0019] The first optical fiber is used to transmit laser light between the laser and the collimating lens, and the second optical fiber is used to transmit reflected light between the detector and the focusing lens. Beneficial Effects

[0020] Compared with placing the laser and detector in the controller and using optical fiber transmission, the laser, detector and optical fiber of the present invention are installed on the probe rod body for laser transmission, which reduces the light loss of laser long-distance transmission and improves accuracy.

[0021] The rear part of the probe rod body is provided with a laser channel and a photosensitive channel;

[0022] One end of the laser channel is connected to one end of the first optical fiber, and the other end of the laser channel is equipped with the collimating lens;

[0023] One end of the photosensitive channel is connected to one end of the first optical fiber; the other end of the photosensitive channel is equipped with the condensing lens. Beneficial Effects

[0024] The laser channel and the photosensitive channel are arranged at the rear of the probe rod, which can minimize the loss in light transmission and improve measurement accuracy.

[0025] The laser channel and the photosensitive channel gradually approach each other along the rear of the probe rod body, and the distance between them is the smallest at the rear end of the probe rod body. The angle between the laser channel and the photosensitive channel is an acute angle.

[0026] Beneficial effect: The angle between the laser channel and the photosensitive channel is an acute angle, and the extended lines converge at one point. Compared with a parallel setting, it can reduce the loss of diffusely reflected light, and the diffusely reflected light is changed to be transmitted to the photosensitive channel at a closer distance, thereby improving accuracy.

[0027] The middle part of the probe rod body is a heat-insulating column of heat-insulating material, and the heat-insulating column is cylindrical, and the heat-insulating material is filled inside the heat-insulating column.

[0028] Beneficial effects: Since the exhaust pipe of the heat engine has a high temperature when the heat engine is working, the heat insulation column of the heat insulation material and the heat insulation material filled inside reduce the heat transfer efficiency and protect the internal electronic components, especially the laser and the detector.

[0029] The front and rear parts of the probe rod body are evenly arranged with annular heat dissipation fins for heat dissipation.

[0030] Beneficial effect: The heat dissipation fins increase the heat exchange area and improve the heat dissipation efficiency.

[0031] The heat dissipation fins are made of aluminum alloy or copper.

[0032] Beneficial effect: The material of the heat sink fins is aluminum alloy or copper with high thermal conductivity, which is not only easy to process and assemble, but more importantly, has good heat dissipation effect.

[0033] The rear part of the probe rod body is threadedly connected to the engine exhaust pipe.

[0034] An exhaust pipe for a fuel engine, comprising an exhaust pipe body, characterized in that it comprises:

[0035] A mounting hole, which passes through the surface of the exhaust pipe body and is used to mount a probe base;

[0036] The probe base is used to install the above-mentioned near backscattering vehicle-mounted particulate matter sensor.

[0037] The lower part of the probe base passes through the mounting hole and is welded to the exhaust pipe body by welding;

[0038] The probe base is provided with an internal thread running through the axial direction, and is threadedly connected to the near backscattering vehicle-mounted particulate matter sensor, so as to facilitate disassembly and cleaning of dirt on the surfaces of the collimating lens and the focusing lens.

[0039] Beneficial effects of the present invention:

[0040] The present invention can monitor the emission of diesel engine particulate matter in real time. According to the diffuse scattering principle and the particle size distribution theory of diesel engine emission particulate matter, the near backscattering method can not only make the measurement range cover more than 90% of the particulate matter, but also greatly improve the monotonic responsiveness of the sensor.

[0041] Placing the laser and detector directly inside the sensor rod independently of the controller reduces the light loss of laser transmission and the amplification factor, thereby reducing the impact of circuit noise signals on measurement accuracy, compared to placing the laser and detector in the controller and using optical fiber for laser transmission.

[0042] The laser and detector are placed at the back, and the laser is transmitted and received using a short hard optical fiber. The use of heat dissipation fins and thermal insulation columns can effectively eliminate the influence of temperature on the laser and detector.

[0043] In addition, the present invention has accurate measurement, fast response, convenient installation and disassembly, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the structural principle of the present invention;

[0045] Figure 2 It is a schematic diagram of the installation structure of the present invention;

[0046] Figure 3 It is a schematic diagram of the working principle of the present invention.

[0047] In the figure, 1-collimating lens, 2-fastening nut, 3-laser channel, 4-probe rod, 5-heat dissipation fins, 6-laser, 7-wiring harness, 8-controller, 9-detector, 10-insulation column, 11-optical fiber, 12-photosensitive channel, 13-focusing lens, 14-probe base, 15-exhaust pipe, 16-laser beam, 17-scattered beam (reflected light), 18-particles. DETAILED DESCRIPTION

[0048] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0049] like Figure 1 and 2As shown, the near backscattering vehicle-mounted particulate matter sensor includes a collimating lens 1, a fastening nut 2, a laser channel 3, a probe rod 4, a heat dissipation fin 5, a laser 6, a wiring harness 7, a controller 8, a detector 9, a heat insulation column 10, an optical fiber 11, a photosensitive channel 12, a focusing lens 13 and an exhaust pipe 15;

[0050] It should be noted that the probe base 14 is installed on the exhaust pipe. The optical fiber 11 between the laser channel 3 and the laser 6 is the first optical fiber; the optical fiber 11 between the photosensitive channel 12 and the detector 9 is the second optical fiber.

[0051] The laser 6, collimating lens 1, focusing lens 13 and detector 9 are installed inside the probe rod body 4; the laser 6 and the detector 9 are located at the front of the probe rod body 4, and the middle of the probe rod body 4 is a heat-insulating column 10 connecting the front and rear of the probe rod body 4. The heat-insulating column 10 is cylindrical and filled with heat-insulating materials. The rear of the probe rod body 4 is provided with a laser channel 3 and a photosensitive channel 12, and the laser channel 3 and the photosensitive channel 12 are respectively installed with a collimating lens 1 and a focusing lens 13 near the rear section of the probe rod body 4.

[0052] The laser channel 3 and the photosensitive channel 12 gradually approach each other along the rear of the probe rod 4, and the distance between them is the smallest at the rear end of the probe rod 4. The angle between the laser channel 3 and the photosensitive channel 12 is an acute angle, preferably 45°. Angles less than 45° and greater than 45° will gradually increase the detection error.

[0053] A first optical fiber is installed between the laser channel 3 and the laser 6 ; a second optical fiber is installed between the photosensitive channel 12 and the detector 9 .

[0054] A fastening nut 2 is installed at the rear of the probe rod body 4. A circular hole with a diameter slightly larger than the probe base 14 is opened on the exhaust pipe of the diesel engine. The probe base 14 is welded to the exhaust pipe by using a spot welding process. The fastening nut 2 at the rear of the probe rod body 4 is threadedly matched with the probe base 14 to install the probe rod body 4 on the probe base 14.

[0055] The controller 8 is connected to the laser 6 and the detector 9 via wiring harnesses 7 respectively.

[0056] Working principle Figure 3 As shown:

[0057] When detecting the concentration of particulate matter in the exhaust gas, the controller 8 controls the laser 6 to emit laser light, and the laser light is transmitted to the collimating lens 1 through the optical fiber 11 and the laser channel 3. The laser light passing through the collimating path is irradiated into the exhaust gas of the exhaust pipe. When the particulate matter 18 in the exhaust gas encounters the irradiation of the laser light, the light beam will be scattered and diffusely reflected in all directions. A part of the scattered light beam 17 converges into the optical fiber 11 through the photosensitive channel 13, and then the detector 9 receives its scattered light signal and converts it into an electrical signal and transmits it to the controller 8. According to the Beer-Lambert law, the intensity of the scattered light increases with the increase of the concentration of particulate matter in the exhaust gas. Therefore, the concentration of particulate matter in the exhaust gas can be obtained by processing the scattered light signal received in the detector 9. The emission of diesel engine particulate matter can be monitored in real time. According to the diffuse scattering principle and the particle size distribution theory of diesel engine exhaust particulate matter, the use of the near backscattering method can not only make the measurement range cover more than 90% of the particulate matter, but also greatly improve the monotonic responsiveness of the sensor. Placing the laser and detector directly inside the sensor rod independently of the controller reduces the light loss of laser transmission and the amplification factor compared to placing the laser and detector in the controller and using optical fiber for laser transmission, thereby reducing the influence of circuit noise signals on measurement accuracy. The laser and detector are placed at the rear, and a hard short optical fiber is used for laser transmission for laser emission and reception. The use of heat dissipation fins and heat insulation columns can effectively eliminate the influence of temperature on the laser and detector. In addition, the present invention has accurate measurement, fast response, easy installation and disassembly, and low cost.

[0058] Since the sensor is installed on the exhaust pipe, the exhaust gas temperature of the exhaust pipe is as high as hundreds of degrees Celsius, so it is important to ensure the normal operation of the internal electronic components. Therefore, the heat insulation column 10 is made of insulating material and filled with insulating material. However, heat will always be generated, so the front and rear of the probe rod body 4 are evenly arranged with annular heat dissipation fins 5 for heat dissipation to accelerate heat dissipation.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Although the applicant has described the present invention in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that those modifications or equivalent substitutions of the technical solution of the present invention without departing from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A near backscattering vehicle-mounted particulate matter sensor, characterized in that: It comprises a probe rod body (4) mounted on the engine exhaust pipe; A laser (6), a collimating lens (1), a focusing lens (13) and a detector (9) are installed inside the probe rod body (4); A laser (6) for emitting laser light to the collimating lens (1); The collimating lens (1) is used to collimate the received laser light, and the collimated laser light is irradiated into the engine exhaust pipe and diffusely reflected on the surface of the exhaust gas particles; A condenser lens (13) is used to receive light that is diffusely reflected from the surface of exhaust gas particles and then irradiates the condenser lens (13), and to condense and emit the light; A detector (9) for receiving the reflected light focused by the focusing lens (13); The controller (8) is connected to the laser (6) and the detector (9) and is used to control the operation of the laser (6) and the detector (9), and to compare the signal intensity of the emitted laser light and the concentrated reflected light to calculate the concentration of the particulate matter; The laser (6) and the detector (9) are installed inside the front part of the probe rod body (4); The rear portion of the probe rod body (4) is detachably mounted on the engine exhaust pipe, and the collimating lens (1) and the focusing lens (13) are mounted on the rear end of the probe rod body (4); A first optical fiber is used to transmit laser light between the laser (6) and the collimating lens (1), and a second optical fiber is used to transmit reflected light between the detector (9) and the focusing lens (13); The rear portion of the probe rod body (4) is provided with a laser channel (3) and a photosensitive channel (12); One end of the laser channel (3) is connected to one end of the first optical fiber, and the other end of the laser channel (3) is mounted with the collimating lens (1); One end of the photosensitive channel (12) is connected to one end of the second optical fiber; the other end of the photosensitive channel (12) is mounted with the focusing lens (13); The laser channel (3) and the photosensitive channel (12) gradually approach each other along the rear portion of the probe rod body (4), and the distance between them is the smallest at the rear end of the probe rod body (4). The angle between the laser channel (3) and the photosensitive channel (12) is an acute angle.

2. The near backscattering vehicle-mounted particulate matter sensor according to claim 1, characterized in that: The middle part of the probe rod body (4) is a heat-insulating column (10) made of heat-insulating material. The heat-insulating column (10) is cylindrical, and the interior of the heat-insulating column (10) is filled with heat-insulating material.

3. The near backscattering vehicle-mounted particulate matter sensor according to claim 2, characterized in that: Annular heat dissipation fins (5) for dissipating heat are evenly arranged on the front and rear of the probe rod body (4).

4. The near backscattering vehicle-mounted particulate matter sensor according to claim 3, characterized in that: The material of the heat dissipation fins (5) is aluminum alloy or copper.

5. The near backscattering vehicle-mounted particulate matter sensor according to claim 4, characterized in that: The rear portion of the probe rod body (4) is threadedly connected to the engine exhaust pipe.

6. A fuel engine exhaust pipe, comprising an exhaust pipe body (15), characterized in that: include: A mounting hole, which passes through the surface of the exhaust pipe body (15) and is used for mounting a probe base (14); A probe base (14) is used for mounting the near backscattering vehicle-mounted particulate matter sensor according to any one of claims 1 to 5.

7. The exhaust pipe of a fuel engine according to claim 6, characterized in that: The lower portion of the probe base (14) passes through the mounting hole and is welded to the exhaust pipe body (15); The probe base (14) is provided with an internal thread that runs through the axial direction and is threadedly connected to the near backscattering type vehicle-mounted particulate matter sensor.

Images