A particle sensor and a testing method thereof

Abstract

The present invention belongs to the field of sensor technology and provides a particulate matter sensor, comprising a high-voltage electrode and a conductive shell, wherein the conductive shell cover is arranged outside the high-voltage electrode and the two are insulated and shielded from each other, and further comprising an insulating member arranged between the high-voltage electrode and the conductive shell, wherein the insulating member is connected to the conductive shell via a metal component to achieve a seal between the insulating member and the conductive shell. The present invention also provides the following test methods: first, the high-voltage pressurization time is fixed, and the particulate matter concentration is calculated through a functional relationship based on the change in the current value or the time-current area during the process. Second, the initial current Imin and the limiting current Imax are fixed, and the particulate matter concentration is calculated through a functional relationship based on the time when the initial current reaches the limiting current. Third, the processing module of the sensor switches the implementation of the above two (different) test methods according to different working conditions. The sensor can quickly enter the working state, self-learn to set the initial current Imin, and eliminate the original error of the sensor.

Description

Technical Field

[0001] The present invention relates to the field of sensing technology, and in particular to a particle sensor and a testing method thereof. Background Art

[0002] Existing particulate matter sensors that use high voltage electrodes for measurement, such as Figure 1 As shown, the device comprises a high-voltage electrode 1. Centered around the high-voltage electrode 1, the device is surrounded, from the inside out, by an inner insulating layer 2, a shielding component 3, an outer insulating layer 4, and a conductive outer shell 5. Both the high-voltage electrode 1 and the shielding component 3 are made of stainless steel. When a voltage of 1000V is applied between the high-voltage electrode 1 and the shielding component 3, the insulation resistance is ≥ 800MΩ; when a voltage of 1000V is applied between the high-voltage electrode 1 and the conductive outer shell 5, the insulation resistance is ≥ 300MΩ. The inner insulating layer 2 provides a seal between the high-voltage electrode 1 and the shielding component 3, while the outer insulating layer 4 provides a seal between the shielding component 3 and the conductive outer shell 5. The seal between the inner insulating layer 2 and the outer insulating layer 4 is primarily achieved by insulating powder 6.

[0003] However, due to ambient humidity and moisture absorption by the insulating powder 6, the insulation resistance between the high-voltage electrode 1 and the shielding component 3, and the insulation resistance between the high-voltage electrode 1 and the conductive housing 5, will not reach the required parameters of 800MΩ and 300MΩ in the measurement circuit. The higher the humidity, the lower the insulation resistance.

[0004] Therefore, the particulate matter sensor needs to be dried before operation. After a period of time, the moisture in the insulating powder 6 in the inner insulating layer 2 and the outer insulating layer 4 is dried out, causing the insulation resistance of the insulating powder 6 to gradually increase to the insulation resistance value required by the measurement circuit. Only then can the particulate matter sensor truly begin to operate.

[0005] In actual use, when particulate matter sensors are installed on off-road vehicles and ships, off-road vehicles are currently mainly modified, and the installation location of the particulate matter sensor is not blocked, which is easily contaminated with mud and water, making the startup time longer. The particulate matter emission concentration of ships is extremely high, and the working environment humidity is high, so the particulate matter sensor is very easy to be blocked and fail.

[0006] Existing particulate matter sensors calculate particulate matter concentration by measuring leakage current and related functional relationships. Leakage current is affected by the length of the particle whiskers. Therefore, each time a particle sensor is activated, the length of the particle whiskers is based on the data from the last time the sensor was activated, meaning the leakage current is based on the previous reading rather than the real-time reading. Therefore, it takes some time for the signal to align with actual operating conditions, leading to initial errors in the test. Summary of the Invention

[0007] The technical problem to be solved by the present invention is: in order to overcome the deficiency of existing particulate matter sensors that need to be dried before operation, and to enable the sensor to still work normally when the particulate matter concentration is too high, the present invention provides a particulate matter sensor and a measurement method.

[0008] In order to achieve the above objectives, the present invention includes the following technical solutions on one hand: a particulate matter sensor, including a sensor, a high-voltage electrode and a conductive shell, the conductive shell cover is arranged outside the high-voltage electrode and the two are insulated and shielded from each other, and also includes an insulating part arranged between the high-voltage electrode and the conductive shell, the insulating part is connected to the conductive shell through a metal part to achieve sealing between the insulating part and the conductive shell.

[0009] In some preferred embodiments, the metal component includes a metal block and a metal pressure ring, the left end of the insulating member is connected to the conductive shell through the metal block, and the conductive shell is connected to the boss of the insulating member through the metal pressure ring.

[0010] In some preferred embodiments, the left end structure of the insulating part is in the form of a step with two steps, the inner wall of the conductive shell is provided with a groove, the butterfly-shaped spring clip is clamped in the groove and is sleeved on the step close to the high-voltage electrode direction, and the metal block is sleeved on the step close to the conductive shell direction.

[0011] In some preferred embodiments, the insulating member is made of an insulating material and includes a left side portion and a right side portion of the insulating member separated by a partition layer in the insulating member. The partition layer is provided with a through hole that penetrates the left and right sides of the insulating member. The high-voltage electrode includes a left electrode and a right electrode provided on both sides of the partition layer. The left electrode and the right electrode are connected by a metal strip that fills and passes through the through hole. In some preferred embodiments, the metal strip includes a first metal strip, a metal member, and a second metal strip. The metal member fills the through hole. The first metal strip and the second metal strip are connected by the metal member and are provided on the inner sidewalls of the left and right sides of the insulating member, respectively.

[0012] In some preferred embodiments, the left electrode includes a guide portion and a terminal portion, wherein the terminal portion is formed by an upward extension of the guide portion and is connected to the first metal strip. In some preferred embodiments, the insulating member is made of ceramic, and the metal strip is made of a high-temperature resistant metal.

[0013] In some preferred embodiments, the particulate matter sensor further includes: the particulate matter sensor further includes: a controller, and when the sensor fails, the controller sends a corresponding signal to a host computer.

[0014] In order to achieve the above purpose, the present invention also includes the following technical solutions: a particle sensor testing method, a time-sharing pressurization method: the conductive shell is grounded, a voltage is applied to the high-voltage electrode, which is switched between a high voltage Vmax and a low voltage Vmin according to a fixed voltage value, the high voltage Vmax, the voltage range is 900V to 1200V, the low voltage Vmin, the voltage range is 300V to 700V, the current value i between the high-voltage electrode (10) and the conductive shell (20) is measured and recorded, the high voltage Vmax is applied, the loading time is t1, and then the low voltage Vmin is switched to the low voltage Vmin. When the current reaches the minimum value, the high voltage Vmax is reloaded and loaded according to the last t1 time. This cycle is repeated until a detection cycle ends, and the particle concentration is calculated according to the current value difference △i or the time voltage area S in each t1 time, and the particle concentration is calculated by the functional relationship between the current value difference △i or the time voltage area S and the particle concentration. The detection is continuously cycled according to the cycle, and the particle concentration value is continuously given.

[0015] In order to achieve the above objectives, the present invention includes the following technical solutions on another aspect: a particulate matter sensor testing method, a limiting current method: the conductive shell is grounded, and a voltage is applied to the high-voltage electrode, which switches between a high voltage Vmax and a low voltage Vmin according to a fixed voltage value. The high voltage Vmax has a voltage range of 900V to 1200V, and the low voltage Vmin has a voltage range of 300V to 700V. The current value i between the high-voltage electrode and the conductive shell is measured and recorded, and the test time t is recorded. The initial current value Imin and the limiting current value Vmax are set, and the high voltage Vmax is applied. When the current reaches the limiting current value Imax, it is switched to the low voltage Vmin. When the current reaches the minimum value, the high voltage Vmax is reloaded. This cycle is repeated until a detection cycle ends. The initial current Imin is fixed. According to the time △t each time the current reaches the limiting current Imax from the initial current Imin, the particulate matter concentration is calculated by the functional relationship between the time △t and the particulate matter concentration. The detection is continuously cycled to continuously give the particulate matter concentration value.

[0016] To achieve the above objectives, the present invention further includes the following technical solutions: a particulate matter sensor testing method, a time-sharing voltage-limiting current method, comprising the following steps:

[0017] S1. Ground the conductive housing;

[0018] S2, setting a high voltage Vmax, a fixed loading time t1, a limiting current Imax, and an initial current Imin, wherein the initial current Imin is smaller than the limiting current Imax;

[0019] S3, applying a high voltage Vmax to the high voltage electrode, measuring and recording the real-time current value i between the high voltage electrode and the conductive shell, and recording the loading time t;

[0020] S4, judging whether the current value i reaches Imax;

[0021] S5. If the current value reaches Imax within the fixed loading time t1, switching to loading a low voltage Vmin when the current reaches Imax, and calculating the particulate matter concentration based on the time Δt from the initial current Imin to the limit current Imax and the functional relationship between the time Δt and the particulate matter concentration;

[0022] If the current values ​​are all less than Imax during the fixed loading time t1, then at the fixed loading time t1, a low voltage Vmin is applied, and the particulate matter concentration is calculated based on the functional relationship between the current difference Δi or the time-voltage-area S during the time t1 and the particulate matter concentration. S6: Apply the low voltage Vmin, and when the current reaches the minimum value, repeat steps S3-S6 until the test ends.

[0023] The high voltage Vmax has a voltage range of 900V to 1200V, the low voltage Vmin has a voltage range of 300V to 700V, and the steps S2 to S6 are controlled and implemented by a processing module of the sensor.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The particulate matter sensor of the present invention utilizes only metal components for sealing the insulating components. Since there is no powder filling, the sensor does not absorb moisture in high humidity, leading to long startup times. It can quickly enter operational mode. This invention is widely applicable to off-road vehicles and marine vessels. Three testing methods are provided, two of which involve limiting the sensor's current value to prevent rapid accumulation of particulate matter and sensor clogging. Self-learning generates or sets the initial current Imin value, eliminating detection errors caused by sensor discreteness errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 : Schematic diagram of the structure of a particle sensor using a high-voltage electrode for measurement in the prior art;

[0027] Figure 2 : Schematic diagram of the cross-sectional structure of the particle sensor in the present invention;

[0028] Figure 3 : Figure 2 Enlarged view of the metal part at A;

[0029] Figure 4 : Schematic diagram of the connection structure between the left electrode and the first metal strip of the present invention;

[0030] Figure 5 : Test diagram of time-sharing pressurization method in the test method of the present invention;

[0031] Figure 6 : Test diagram of the limiting current method in the test method of the present invention;

[0032] Figure 7 : Test diagram of time-sharing voltage-limiting current method in the test method of the present invention;

[0033] Figure 1 Middle: 1. High-voltage electrode 1; 2. Insulation layer; 3. Shielding parts; 4. Outer insulation layer; 5. Conductive shell; 6. Insulation powder;

[0034] Figure 2-4 Middle: 10, high-voltage electrode; 20, conductive shell; 30, insulating part; 40, metal part; 50, metal strip; 11, left electrode; 12, right electrode; 13, guide part; 14, terminal part; 21, groove; 31, shoulder; 32, left side of insulating part; 33, right side of insulating part; 34, through hole; 41, metal block; 42, metal pressure ring; 43, butterfly spring; 51, first metal strip; 52, metal part; 53, second metal strip. DETAILED DESCRIPTION

[0035] The present invention will now be described in further detail with reference to the accompanying drawings.

[0036] like Figure 2 As shown, a particulate matter sensor includes a high-voltage electrode 10 and a conductive housing 20. The conductive housing 20 is disposed over the high-voltage electrode 10, and the two are insulated and shielded from each other. The sensor also includes an insulating member 30 disposed between the high-voltage electrode 10 and the conductive housing 20. The insulating member 30 is connected to the conductive housing 20 via a metal member 40 to achieve a seal between the insulating member 30 and the conductive housing 20. The present invention achieves a seal between the insulating member 30 and the conductive housing 20 solely through the metal member 40, eliminating the need for multiple insulating layers or specialized hygroscopic insulating powder. Consequently, the internal particulate matter sensor does not require a dedicated heater to remove moisture from the hygroscopic insulating powder to increase resistance. Consequently, the particulate matter sensor of the present invention has a simple structure, low manufacturing cost, a smaller and more compact size, and a longer service life.

[0037] Please continue reading Figure 2The metal component 40 separates the insulating member 30 and the conductive housing 20 to form an annular enclosed space. It is understood that the metal component 40 can separate the insulating member 30 and the conductive housing 20 to form a larger space or directly fit the insulating member 30 and the conductive housing 20 above and below without leaving any gaps. For structural stability and material conservation, a single enclosed space is preferred. This design is simple and easier to install at a lower cost. The metal component 40 can effectively seal the insulating member 30 and the conductive housing 20 through an interference fit and / or a press fit.

[0038] Preferably, the metal component 40 includes a metal block 41 and a metal pressure ring 42, the left end of the insulating member 30 is connected to the conductive shell 20 through the metal block 41, and the conductive shell 20 is connected to the shoulder 31 of the insulating member 30 through the metal pressure ring 42. More preferably, Figure 2 The conductive housing 20 shown also has a protrusion. A metal pressure ring 42 is clamped between the shoulder 31 and the protrusion of the conductive housing 20. This compact structure limits the horizontal movement of the metal pressure ring 42, improving sealing and structural stability. The metal block 41 achieves an interference fit seal, while the sealing metal pressure ring 42 achieves a press fit seal.

[0039] Specifically, the left end of the insulating member 30 is structured in a stepped manner with two steps. The inner wall of the conductive housing 20 is provided with a groove 21. A butterfly spring 43 is engaged within the groove 21 and is mounted on the step facing the high-voltage electrode. The metal block 41 is mounted on the step facing the conductive housing 20. More preferably, the metal block 41 abuts the butterfly spring 43. Because exhaust gas often carries high heat, the butterfly spring 43 transmits axial force to the metal pressure ring 42, compressing it tightly. This prevents the sensor from leaking due to gaps in the metal ring 42 caused by thermal expansion and contraction. This simple method further improves the structural stability between the insulating member 30 and the conductive housing 20. It is understood that the conductive housing 20 can be a single-piece structure or, as in the illustrated embodiment, can be constructed from multiple modules. For example, one module of the conductive housing can be compressed with the butterfly spring 43 and then welded to another module of the conductive housing.

[0040] The insulating member 30 is made of an insulating material and includes a left side portion 32 and a right side portion 33 separated by a partition layer in the insulating member 30. The partition layer is provided with a through hole 34 that passes through the left and right sides of the insulating member 33. The partition layer is used to improve the structural strength of the insulating member 30 and better support the overall product. The high-voltage electrode 10 includes a left electrode 11 and a right electrode 12 arranged on both sides of the partition layer. The left electrode 11 and the right electrode 12 are connected by a metal strip 50 that fills and passes through the through hole 34. Because the insulating member 30 divides the high-voltage electrode 10 into two left and right parts, the present invention does not use an electrode rod or something similar as an electrode rod as the high-voltage electrode 10, which can reduce the use of high-voltage electrode 10 materials and save costs. The metal strip 50 is made of a high-temperature resistant metal, such as one of nickel, manganese molybdenum, platinum, palladium, or a mixture of nickel paste and manganese molybdenum. More preferably, the insulating member 30 is made of ceramic.

[0041] See Figure 2 and Figure 3 The metal strip 50 comprises a first metal strip 51, a metal member, and a second metal strip 53. The metal member fills the through-hole 34. The first metal strip 51 and the second metal strip 53 are connected by the metal member and are respectively located on the inner sidewalls of the left and right sides 32 and 33 of the insulating member. The first metal strip 51 contacts and connects to the left electrode 11, while the second metal strip 53 contacts and connects to the right electrode 12. In this way, the left and right electrodes 12 are electrically connected through the metal material within the insulating member 30. In this embodiment, the metal strip 50 is manufactured by coating the inner sidewalls of the left and right sides 32 and 33 of the ceramic insulating member with platinum paste, pouring the platinum paste into the through-hole 34, and then firing at high temperature. This ensures that the metal strip is tightly bonded to the insulating member 30 and does not easily fall off. The insulating member 30 is preferably integrally formed, providing a stable structure and ease of manufacture. Platinum wires connect the front and rear electrodes, significantly improving the product's startup time. Experiments conducted by the applicant have found that the above-described insulating member 30 structure also helps reduce the use of metal strip material and lower costs.

[0042] Furthermore, through the installation and coordination of the ceramic insulating part 30 and the butterfly-shaped spring piece, the metal block and the metal pressure ring, the present invention does not experience layer slippage, has good stability and a longer service life compared to the particulate matter sensor in which the high-voltage electrode 10, the insulating part 30 and the conductive shell 20 are simply arranged in sequence from the inside to the outside and the gaps are filled with insulating powder.

[0043] like Figure 2 and Figure 4As shown, the left electrode 11 includes a guide portion 13 and a terminal portion 14. The terminal portion 14 is formed by the upward extension of the guide portion 13 and is connected to the first metal strip 51. In the illustrated embodiment, the left and right sides 33 of the insulating member are hollow, reducing the overall weight of the particulate matter sensor. The terminal portion 14 is flexible and can be easily inserted into the left side portion 32 of the insulating member and abut against the first metal strip 51 during installation. To facilitate insertion of the terminal portion 14 into the insulating member, a plug with a smaller diameter than the terminal portion 14 is provided in front of the terminal portion 14.

[0044] The particle sensor further includes a controller (not shown in the figure). When the particle sensor fails, the controller sends a corresponding signal to a host computer and performs self-diagnosis.

[0045] The measurement principle of the particle sensor of the present invention is as follows:

[0046] The conductive shell 20 is grounded, and a voltage is applied to the high-voltage electrode 10. The gas to be measured enters the particulate matter sensor from the exhaust gas inlet and flows through the gap between the high-voltage electrode 10 and the conductive shell 20. The particulate matter in the gas to be measured is ionized or polarized into a conductor by the high-voltage electrode 10, and other substances in the gas to be measured are not ionized or polarized into a conductor. The current difference between the high-voltage electrode 10 and the conductive shell 20 and the current conversion time are measured, and the concentration of the particulate matter in the gas to be measured is obtained according to the functional relationship between the current difference between the high-voltage electrode 10 and the conductive shell 20 and the current conversion time and the concentration of the particulate matter.

[0047] A particle sensor test method, time-sharing pressurization method, the test diagram is as follows Figure 5 As shown, the conductive housing 20 is grounded. A voltage switching between a high voltage Vmax and a low voltage Vmin is applied to the high-voltage electrode 10 at fixed values. The high voltage Vmax ranges from 900V to 1200V, and the low voltage Vmin ranges from 300V to 700V. The current i between the high-voltage electrode 10 and the conductive housing 20 is measured and recorded. The high voltage Vmax is applied for a time t1, then the voltage is switched to the low voltage Vmin. When the current reaches its minimum, the high voltage Vmax is reapplied for the same time t1 as before. This cycle continues until a detection cycle is completed. The particle concentration is calculated based on the current difference △i or the time-voltage area S (S = ∫idt) during each time t1. The function relationship between this current difference △i or the time-voltage area S and the particle concentration is used. The detection cycle continues, continuously providing the particle concentration value. The value of T1 is generally 5-20s.

[0048] A particle sensor test method, limiting current method, the test diagram is as follows Figure 6As shown: the conductive shell 20 is grounded, and a voltage is applied to the high-voltage electrode 10 that switches between a high voltage Vmax and a low voltage Vmin at a fixed voltage value. The high voltage Vmax has a voltage range of 900V to 1200V, and the low voltage Vmin has a voltage range of 300V to 700V. The current value i between the high-voltage electrode 10 and the conductive shell 20 is measured and recorded, and the test time t is recorded. The initial current value Imin and the limiting current value Vmax are set, and the high voltage Vmax is loaded. When the current reaches the limiting current value Imax, it is switched to the low voltage Vmin. When the current reaches the minimum value, the high voltage Vmax is reloaded. This cycle is repeated until a detection cycle ends. The initial current Imin is fixed. According to the time △t each time the current reaches the limiting current Imax from the initial current Imin, the particle concentration is calculated through the functional relationship between the time △t and the particle concentration. The detection is continuously cycled to continuously give the particle concentration value.

[0049] A particle sensor test method, time-sharing voltage-limiting current method, the measurement diagram is as follows Figure 7 As shown: The following steps are included:

[0050] S1, grounding the conductive housing 20;

[0051] S2. Set the high voltage Vmax, fixed loading time t1, limit current Imax and initial current Imin. The initial current Imin is less than the limit current Imax. The value of T1 is generally 5-20s.

[0052] S3, applying a high voltage Vmax to the high voltage electrode 10, measuring and recording the real-time current value i between the high voltage electrode 10 and the conductive housing 20 and recording the loading time t;

[0053] S4, judging whether the current value i reaches Imax;

[0054] S5. If the current value reaches Imax within the fixed loading time t1, switching to loading a low voltage Vmin when the current reaches Imax, and calculating the particulate matter concentration based on the time Δt from the initial current Imin to the limit current Imax and the functional relationship between the time Δt and the particulate matter concentration;

[0055] If the current values ​​are all less than Imax during the fixed loading time t1, then at the fixed loading time t1, a low voltage Vmin is applied, and the particulate matter concentration is calculated based on the functional relationship between the current difference Δi or the time-voltage-area S during the time t1 and the particulate matter concentration. S6: Apply the low voltage Vmin. When the current reaches the minimum value, repeat steps S3-S6 until the test ends.

[0056] The high voltage Vmax ranges from 900V to 1200V, and the low voltage Vmin ranges from 300V to 700V. Steps S2-S6 are controlled and implemented by the sensor's processing module. It should be noted that the sensor's control module can self-learn and make corrections during actual operation by setting the high voltage fixed loading time t1 and the predetermined initial current Imin.

[0057] In the embodiment of the present invention, the insulation resistance between the high-voltage electrode 10 and the shielding component 30, measured using an insulation resistance meter, was found to be greater than the 1 GΩ technical parameter required by the particle sensor. The insulation resistance between the high-voltage electrode 10 and the conductive housing 20, also measured using an insulation resistance meter, was found to be greater than the 800 MΩ technical parameter required by the particle sensor.

[0058] Compared with the particulate matter sensor that has initial test errors due to the most direct data collection, the method of the present invention collects the current change within a period of time or the time used for a fixed current change segment, so there is no initial error, the particulate matter sensor does not need to be activated, and the test mode can be freely switched according to the engine operating conditions.

[0059] For example: Example 1: Test diagram Figure 5 As shown, the conductive housing 20 is grounded. Under a low voltage of 400V, the initial current Imin is 50NA. A high voltage of 1000V is applied to the high voltage electrode 10. The current value between the high voltage electrode 10 and the conductive housing 20 is measured and recorded. When the high voltage is applied for 10s, the current is measured to be 150NA. At this time, the current difference is 100NA. The particle concentration calculated by the function is 80mg / m 3 Then switch to load a low voltage of 400V, and reload a high voltage of 1000V when the current reaches the initial current Imin, and repeat this cycle.

[0060] Example 2: Test diagram Figure 6 As shown in the figure, the conductive shell 20 is grounded, the initial current value is set to 50NA and the limiting current value is set to 600NA. Under the low voltage of 400V, when the initial current value reaches 50NA, a high voltage of 1000V is applied to the high voltage electrode 10. The time for the current value between the high voltage electrode 10 and the conductive shell 20 to reach the limiting current value of 600NA is measured and recorded as 6s. According to the relationship between time and particle concentration, the particle concentration is calculated to be 400mg / m 3 When the current reaches 600NA, it switches to a low voltage of 400V. When the current reaches the initial current value, it reloads a high voltage of 1000V, and the cycle continues.

[0061] Example 3: Time-sharing voltage-limiting current method: Test diagram as shown Figure 7 As shown: the conductive housing 20 is grounded;

[0062] Set a high voltage fixed loading time of 10s, a preset maximum current of 600NA and an initial current of 50NA; load a high voltage of 1000V on the high voltage electrode 10, measure and record the real-time current value I between the high voltage electrode 10 and the conductive shell 20 and the recording loading time; judge whether the current value reaches 600NA within the fixed high voltage loading time of 10s; it can be seen from the figure that under the high voltage loading state, the maximum current within 10s does not exceed the preset maximum current of 600NA. After 10s, switch to loading a low voltage of 400V, and according to the difference in the current value for 10s, the first test particle concentration is calculated through the functional relationship between the difference in the current value and the particle concentration; when loading the low voltage, when the current reaches the minimum value, load a high voltage of 1000V on the high voltage electrode 10. It can be seen from the figure that the current value has reached 600NA in less than 6s. When the current value reaches 600NA, switch to loading a low voltage of 400V, and according to the time when the current reaches the initial current of 50NA and reaches 600NA, the particle concentration is calculated through the functional relationship between the above time and the particle concentration.

[0063] Although the present invention has been described above with reference to certain embodiments thereof, the present invention is not limited to the above embodiments. A person skilled in the art may make various modifications and variations to the above embodiments based on the above description. The scope of the present invention is defined by the appended claims.

Claims

1. A particulate matter sensor, comprising a sensor, a high-voltage electrode (10) and a conductive housing (20), wherein the conductive housing (20) is disposed outside the high-voltage electrode (10) and the two are insulated and shielded from each other, and further comprising an insulating member (30) disposed between the high-voltage electrode (10) and the conductive housing (20), characterized in that: The insulating member (30) is connected to the conductive shell (20) through a metal component (40) to achieve sealing between the insulating member (30) and the conductive shell (20); the metal component (40) includes a metal block (41) and a metal pressure ring (42); the left end of the insulating member (30) is connected to the conductive shell (20) through the metal block (41), and the conductive shell (20) is connected to the boss (31) of the insulating member (30) through the metal pressure ring (42); the left end structure of the insulating member (30) is a stepped form with two steps, the inner wall of the conductive shell (20) is provided with a groove (21), the butterfly spring (43) is clamped in the groove (21) and is sleeved on the step close to the high-voltage electrode (10), and the metal block (41) is sleeved on the step close to the conductive shell (20); The insulating member (30) includes a left side portion (32) and a right side portion (33) of the insulating member separated by a partition layer in the insulating member, the partition layer is provided with a through hole (34) penetrating the left and right sides of the insulating member, the high-voltage electrode (10) includes a left electrode (11) and a right electrode (12) provided on both sides of the partition layer, the left electrode (11) and the right electrode (12) are connected by a metal strip (50), and the metal strip (50) fills and passes through the through hole (34).

2. A particulate matter sensor according to claim 1, characterized in that: The metal strip (50) includes a first metal strip (51), a metal piece (52) and a second metal strip (53), wherein the metal piece (52) is filled in the through hole (34), and the first metal strip (51) and the second metal strip (53) are connected by the metal piece (52) and are respectively arranged on the inner side walls of the left side portion (32) and the right side portion (33) of the insulating piece.

3. A particulate matter sensor according to claim 2, characterized in that: The left electrode (11) comprises a guide portion (13) and a terminal portion (14), wherein the terminal portion (14) is formed by extending the guide portion (13) upward, and the terminal portion (14) is connected to the first metal strip (51).

4. The particulate matter sensor according to claim 1, characterized in that: The insulating member (30) is made of ceramic material, and the metal strip (50) is made of high-temperature resistant metal.

5. The particulate matter sensor according to claim 1, characterized in that: The particulate matter sensor further includes a controller, which sends a corresponding signal to a host computer when the sensor fails.

6. A particle sensor testing method, characterized in that: Time-sharing pressure method: the conductive shell (20) is grounded, and a voltage is applied to the high-voltage electrode (10) that switches between a high voltage Vmax and a low voltage Vmin according to a fixed voltage value. The high voltage Vmax has a voltage range of 900V to 1200V, and the low voltage Vmin has a voltage range of 300V to 700V. The current value i between the high-voltage electrode (10) and the conductive shell (20) is measured and recorded. The high voltage Vmax is applied for a loading time of t1, and then the voltage is switched to the low voltage Vmin. When the current reaches the minimum value, the high voltage Vmax is re-applied and loaded according to the last t1 time. This cycle is repeated until a detection cycle ends. According to the current value difference △i or the time-voltage area S in each t1 time, the particle concentration is calculated through the functional relationship between the current value difference △i or the time-voltage area S and the particle concentration. The detection is continuously cycled and the particle concentration value is continuously given.

7. A particle sensor testing method, characterized in that: Limiting current method: The conductive shell (20) is grounded, and a voltage is applied to the high-voltage electrode (10) that switches between a high voltage Vmax and a low voltage Vmin at a fixed voltage value. The high voltage Vmax has a voltage range of 900V to 1200V, and the low voltage Vmin has a voltage range of 300V to 700V. The current value i between the high-voltage electrode (10) and the conductive shell (20) is measured and recorded, and the test time t is recorded. The initial current value Imin and the limiting current value Vmax are set, and the high voltage Vmax is applied. When the current reaches the limiting current value Imax, it is switched to the low voltage Vmin. When the current reaches the minimum value, the high voltage Vmax is re-applied. This cycle is repeated until a detection cycle ends. The initial current Imin is fixed, and the particle concentration is calculated based on the time △t from the initial current reaching Imin to the limiting current Imax each time. The functional relationship between the time △t and the particle concentration is used. The detection is continuously repeated in a cycle to continuously give the particle concentration value.

8. A particle sensor testing method, characterized in that: Time-sharing voltage-limiting current method: includes the following steps: S1, grounding the conductive housing (20); S2, setting a high voltage Vmax, a fixed loading time t1, a limiting current Imax, and an initial current Imin, wherein the initial current Imin is smaller than the limiting current Imax; S3, applying a high voltage Vmax to the high voltage electrode (10), measuring and recording a real-time current value i between the high voltage electrode (10) and the conductive housing (20), and recording the loading time t; S4, judging whether the current value i reaches Imax; S5. If the current value reaches Imax within the fixed loading time t1, switching to loading a low voltage Vmin when the current reaches Imax, and calculating the particulate matter concentration based on the time Δt from the initial current Imin to the limit current Imax and the functional relationship between the time Δt and the particulate matter concentration; If the current values ​​are all less than Imax during the fixed loading time t1, then at the fixed loading time t1, a low voltage Vmin is applied, and the particulate matter concentration is calculated based on the functional relationship between the current difference Δi or the time-voltage-area S during the time t1 and the particulate matter concentration. S6: Apply the low voltage Vmin. When the current reaches the minimum value, repeat steps S3-S6 until the test ends. The high voltage Vmax has a voltage range of 900V to 1200V, the low voltage Vmin has a voltage range of 300V to 700V, and the steps S2 to S6 are controlled and implemented by a processing module of the sensor.

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