Urea quality detection device for measuring liquid level and concentration through multiple sensors

Abstract

The utility model discloses a urea quality detection device for measuring liquid level and concentration through a plurality of sensors. The urea quality detection device comprises a liquid level pipe, a floater, a sensor group, an anti-bubble bracket and a control panel, the control panel comprises a microprocessor MCU. The sensor group comprises a top distance measuring sensor, a bottom distance measuring sensor, a temperature-humidity sensor and a concentration sensor; the liquid level pipe is arranged in the urea solution tank, and a floater which floats up and down along with the liquid level of the urea solution is arranged in the liquid level pipe; a top distance measuring sensor is mounted at the top of the liquid level pipe; a bottom distance measuring sensor is mounted at the bottom of the liquid level pipe; a temperature and humidity sensor is mounted on the liquid level pipe; and a concentration sensor is arranged at the bottom of the urea solution tank. A plurality of probes are used for cooperative work, when one probe loses efficacy, accurate numerical values of urea concentration and liquid level data can be obtained by processing measurement data of the remaining probes through the MCU, and the problem that in traditional urea quality measurement, the whole device loses efficacy due to the fact that one probe loses efficacy is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of liquid level sensors, and particularly relates to a urea quality detection device for measuring liquid level and concentration through multiple sensors. Background Technique

[0002] At present, as a source of air pollution, automotive exhaust gas, adopting the SCR (Selective Catalytic Reduction Technology) technical route to reduce NOx emissions is the best choice for many diesel vehicles. Urea solution provides the required reducing agent NH3 for the reaction in the SCR catalytic device. Therefore, it is necessary to monitor the liquid level, concentration, temperature, and purity of urea in the urea tank in real time to ensure the smooth progress of the reaction.

[0003] Existing types of liquid level measurement include: tuning fork vibration type, magnetic float type, pressure type, ultrasonic wave, sonar wave, magnetic flap, radar, etc. The liquid level gauge of the tunneling magnetoresistive sensor has high production and processing costs and complex maintenance. The submersible liquid level sensor uses the piezoresistive effect of a diffused silicon or ceramic sensitive element to convert pressure into an electrical signal, which is converted into a 4-20mA current signal output after temperature compensation and linear correction to measure the liquid level accordingly, and the probe is fixed, but it has a single function and cannot distinguish the density of the solution. There will be certain errors when using the reference density for liquid level conversion. The ultrasonic sensor places the sensor probe under the urea liquid level. When the urea concentration is unknown, measuring the liquid level by the ultrasonic wave propagation speed in the urea solution will cause errors; when the vehicle is driving on a bumpy road surface, there will be more bubbles in the urea solution, and the existence of bubbles will cause the liquid level measurement signal of urea to jump; when the vehicle is driving on an inclined road surface, the urea tank will tilt accordingly, while the liquid level remains horizontal. At this time, the ultrasonic probe may not be able to receive the reflection signal at the liquid level, resulting in the situation that the liquid level signal cannot be output or the signal is distorted.

[0004] At present, there are also some multi-functional sensors that can measure the temperature, concentration, and liquid level of urea simultaneously and make a comprehensive judgment to detect the urea solution in real time. Chinese Patent Publication CN217112179U provides a modular urea quality sensor based on ultrasonic waves, but its liquid level measurement only uses one probe, and its reliability against probe failure is not high. There are also disadvantages such as poor readability of liquid level data and slow response speed of liquid level change when the liquid surface shakes or tilts. Content of the Utility Model

[0005] The purpose of the utility model is to provide a urea quality detection device for measuring liquid level and concentration through multiple sensors. The urea quality detection device includes: a liquid level tube, a float, a sensor group, an anti-bubble bracket, and a control board;

[0006] The control board includes a microprocessor MCU;

[0007] The sensor group includes: a top ranging sensor, a bottom ranging sensor, a temperature-humidity sensor, and a concentration sensor;

[0008] The liquid level tube is arranged in the urea solution tank, and a float that floats up and down with the liquid level of the urea solution is installed in the liquid level tube;

[0009] The top ranging sensor is installed at the top of the liquid level tube, and the bottom ranging sensor is installed at the bottom of the liquid level tube;

[0010] The temperature-humidity sensor is installed in the upper section of the liquid level tube, and the concentration sensor is arranged at the bottom of the urea solution tank.

[0011] For the urea quality detection device as described in the present utility model, the float is made of rubber or plastic;

[0012] Preferably, the float is made of nitrile rubber.

[0013] The outer shape of the side surface of the float matches the internal configuration of the liquid level tube;

[0014] n ribs extending from the upper end to the lower end of the float are arranged on the side surface of the float, where n≥2;

[0015] An upper reflecting sheet capable of reflecting the ranging signal of the top ranging sensor is arranged on the top surface of the float;

[0016] A lower reflecting sheet capable of reflecting the ranging signal of the bottom ranging sensor is arranged on the bottom surface of the float.

[0017] For the urea quality detection device as described in the present utility model, both the top ranging sensor and the bottom ranging sensor are ultrasonic sensors;

[0018] The ultrasonic sensor includes a ceramic transducer.

[0019] For the urea quality detection device as described in the present utility model, the top ranging sensor is a laser rangefinder, and the laser rangefinder includes a laser emission and reception component;

[0020] The bottom ranging sensor is an ultrasonic sensor, and the ultrasonic sensor includes a ceramic transducer.

[0021] For the urea quality detection device as described in the present utility model, the MCU controls the laser emission and reception component to emit a laser ranging signal with a fixed wavelength, and the MCU receives and processes the ranging information output by the laser emission and reception component.

[0022] For the urea quality detection device described in the present utility model, the MCU inputs an excitation signal with a predetermined frequency and a predetermined time interval to the ceramic transducer. The excitation signal drives the ceramic transducer to emit ultrasonic waves with a fixed frequency to the lower reflector and / or the upper reflector of the float. After the ultrasonic waves are reflected by the reflector, they are received by the corresponding ceramic transducer and generate echo information of the ultrasonic waves. The echo information is processed by a filter amplification circuit and then input to the MCU for arithmetic execution processing.

[0023] For the urea quality detection device described in the present utility model, inside the urea solution tank, the lower end of the liquid level tube is provided with the concentration sensor.

[0024] The concentration sensor includes a third sensor and a first reflector that are oppositely arranged at a predetermined distance; the third sensor is an ultrasonic sensor.

[0025] For the urea quality detection device described in the present utility model, the ultrasonic sensor includes a ceramic transducer. The MCU inputs an excitation signal with a predetermined frequency and a predetermined time interval to the ceramic transducer, so that the ceramic transducer emits ultrasonic waves with a predetermined frequency to the first reflector. After the ultrasonic waves are reflected by the first reflector, they are received by the ceramic transducer to generate echo information. The echo information is processed by a filter amplification circuit and then input to the MCU for arithmetic execution processing.

[0026] For the urea quality detection device described in the present utility model, the temperature-humidity sensor measures the ambient temperature and humidity around the urea quality sensor, and the output information of the temperature-humidity sensor is input to the MCU for arithmetic processing.

[0027] For the urea quality detection device described in the present utility model, a liquid inlet and an anti-bubble bracket are arranged at the bottom position of the liquid level tube. A filter screen and a detachable filter screen cover are installed at the inlet of the liquid inlet. The urea solution enters the liquid level tube through the liquid inlet and the holes at the bottom of the anti-bubble bracket in sequence.

[0028] The method of the present utility model has the following advantages:

[0029] By using multiple probes to work together, under normal working conditions, the measurement results of multiple probes can be mutually verified using an algorithm to obtain more accurate urea concentration and liquid level data. When one of the probes fails, the measurement data of the remaining probes can be processed by the MCU to obtain accurate values of the urea concentration and liquid level data, and then determine whether the concentration and remaining amount of the urea catalyst can meet the smooth and effective progress of the catalytic reaction, ensuring the environmental protection standards of vehicle exhaust emissions, improving the safety of the vehicle during driving, and solving the problem in traditional urea quality measurement that when one probe fails, the urea concentration and liquid level data of the entire device cannot be detected.

[0030] The above description is only an overview of the technical solution of the present utility model. In order to better understand the technical means of the present utility model, it can be implemented according to the content of the description. Moreover, in order to make the above and other purposes, features and advantages of the present utility model more obvious and understandable, the following preferred embodiments are specifically given and described in detail in conjunction with the accompanying drawings. Description of the Drawings

[0031] Figure 1 Schematic diagram of the principle of the urea quality detection device of the present utility model.

[0032] Figure 2 Schematic diagram of the urea concentration sensor of the present utility model;

[0033] Figure 3 Diagram showing the dimensions of the urea quality detection device of the present utility model;

[0034] Figure 4 Structure diagram of the bottom of the liquid level tube of the present utility model;

[0035] Figure 5 Schematic diagram of the structure of the float of the present utility model.

[0036] Among them, 1. Top ranging sensor; 2. Bottom ranging sensor; 3. Float; 4. Liquid level surface; 5. Air; 6. Urea solution; 7. Liquid level tube; 8. Concentration sensor; 9. First reflector; 10. Anti-bubble bracket; 11. Filter screen; 12. Filter screen cover; 13. Upper reflector; 14. Lower reflector. Detailed Description of the Preferred Embodiment

[0037] The present utility model provides a device applied to a urea quality liquid level sensor, which uses multiple probes to measure the concentration and liquid level height of urea solution. The sensors used for measurement include a float inlaid with a measurement signal reflecting surface, and the urea quality liquid level sensor also has a temperature-humidity sensor.

[0038] The present utility model has at least two liquid level ranging sensors. Among them, a top ranging sensor is arranged at the top of the liquid level tube, and a bottom ranging sensor is arranged at the bottom of the liquid level tube. A float that floats up and down with the liquid level of the urea solution is placed in the middle of the liquid level tube. After the ranging signal emitted by the ranging sensor is reflected by the reflectors on the upper and lower surfaces of the float, the ranging sensor generates reflected signal information. The microprocessor processes the reflected signal information output by the ranging sensor to obtain the liquid level height of the urea solution. At the same time, a temperature-humidity sensor is also arranged near the top of the liquid level tube, and a concentration sensor is at the bottom of the sensor.

[0039] An alternative solution is to use a laser rangefinder to replace the top ranging sensor and use a laser reflection receiving component to replace the ceramic transducer of the ranging sensor.

[0040] The technical solution of the present utility model will be clearly and completely described below in conjunction with specific implementation schemes. However, those skilled in the art should understand that the implementation schemes described below are only used to illustrate the present utility model and should not be regarded as limiting the scope of the present utility model. Based on the implementation schemes in the present utility model, all other implementation schemes obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present utility model.

[0041] The purpose of the present utility model is to provide a urea quality detection device for measuring liquid level and concentration through multiple sensors. The urea quality detection device includes: a liquid level tube 7, a float 3, a sensor group, an anti-bubble bracket 10, and a control board (not shown);

[0042] The control board includes a microprocessor MCU;

[0043] The sensor group includes: a top ranging sensor 1, a bottom ranging sensor 2, a temperature-humidity sensor, and a concentration sensor 8;

[0044] The liquid level tube 7 is arranged in the urea solution tank, and a float 3 that floats up and down with the liquid level of the urea solution is installed in the liquid level tube 7;

[0045] The top ranging sensor 1 is installed at the top of the liquid level tube 7, and the bottom ranging sensor 2 is installed at the bottom of the liquid level tube 7;

[0046] The temperature and humidity sensor is installed at the top of the liquid level tube 7, and the concentration sensor 8 is arranged at the bottom of the urea solution tank.

[0047] The working process of the present utility model is as follows:

[0048] Example 1

[0049] The schematic diagram of the principle of the urea quality detection device of the present utility model is as shown in the appendix Figure 1 as shown.

[0050] The top ranging sensor 1 is provided at the top of the liquid level tube 7. A temperature-humidity sensor is provided near the top of the liquid level tube 7. The bottom ranging sensor 2 is installed at the bottom of the liquid level tube 7. Inside the urea solution tank, a concentration sensor is arranged horizontally near the bottom of the liquid level tube 7. The concentration sensor includes a ceramic transducer, and a first reflector 9 that is opposite to the ceramic transducer at a predetermined distance from the ceramic transducer.

[0051] The top ranging sensor 1 arranged at the top of the liquid level tube 7 uses an ultrasonic sensor including a ceramic transducer. The microprocessor MCU controls the ceramic transducer to emit ultrasonic signals to the float 3 located in the middle of the liquid level tube 7.

[0052] As shown in the appendix Figure 5As shown, a rib structure protruding from the side surface of the float 3 is provided around the float 3. This rib structure ensures that the liquid can smoothly return to the liquid surface through the gap between the ribs of the float 3 and the liquid level tube 7. At the same time, the float can smoothly float up and down with the liquid surface. This rib structure can also prevent the tilt angle of the float 3 from being too large. Upper and lower reflecting sheets 13 and 14 made of stainless steel are embedded on the upper and lower surfaces of the float. The reflecting sheets made of stainless steel are used to enhance the reflection intensity of ultrasonic signals.

[0053] In the urea quality detection device of the present utility model, the float is made of rubber or plastic; preferably, the float is made of nitrile rubber.

[0054] The outer shape of the side surface of the float 3 matches the internal configuration of the liquid level tube 7.

[0055] n ribs extending from the upper end to the lower end of the float 3 are provided on the side surface of the float 3, where n≥2; preferably, n = 4.

[0056] An upper reflecting sheet 13 capable of reflecting the ranging signal of the top ranging sensor 1 is provided on the top surface of the float 3.

[0057] A lower reflecting sheet 14 capable of reflecting the ranging signal of the bottom ranging sensor 2 is provided on the bottom surface of the float 3. The concentration sensor includes a ceramic transducer. The microprocessor MCU controls the ceramic transducer to emit ultrasonic waves in the horizontal direction. A first reflecting sheet 9 made of stainless steel is fixed at a fixed distance on the side opposite to the ultrasonic wave emitting surface of the ceramic transducer for reflecting ultrasonic waves.

[0058] The working process of the concentration sensor is as follows:

[0059] When working, the microprocessor MCU on the control board inputs an excitation signal with a fixed frequency and time to the ceramic transducer of the concentration sensor, so that it emits ultrasonic waves with a fixed frequency towards the first reflecting sheet 9 in the concentration probe. After the sound waves are reflected by the reflecting surface and received by the ceramic transducer, an echo signal is generated. The echo signal is filtered and amplified by the filter amplification circuit to remove interference and amplify it, and then the MCU cooperates with a high-performance time interval digital converter (TDC) chip to calculate the sound wave flight time t3 from the emission of the ultrasonic wave to the reception of the echo signal. Given that the distance between the ceramic transducer and the first reflecting sheet 9 is L3, the propagation speed ν3 of the sound wave in the current medium can be calculated by combining L3 and t3.

[0060]

[0061] The current system temperature T (°C) is measured by the temperature-humidity probe. Combining with Formula 1, the urea concentration z1 can be calculated based on the relationship between the urea concentration z1, temperature, and speed.

[0062]

[0063] The coefficients a, b, c, d, and e in Formula 2 are obtained by fitting experimental data. Since the distance L3 from the ceramic transducer to the first reflector 9 is known, the urea concentration z1 can be directly calculated by the built-in program of the MCU.

[0064] Example 2

[0065] As shown in the appendix Figure 5 The structure of the float 3 is shown. When the urea quality detection device is working, the microprocessor MCU on the control board inputs an excitation signal with a fixed frequency and time to the ceramic transducer of the bottom distance sensor 2, making it emit ultrasonic waves with a fixed frequency towards the lower surface of the float 3 in the liquid level tube 7. The sound wave is reflected by the lower reflecting surface 14 and then received by the ceramic transducer of the bottom distance sensor 2 to generate echo information. After being processed by the filter amplification circuit, the MCU cooperates with the high-performance TDC chip to calculate the sound wave flight time t2 from the start of ultrasonic wave emission by the ceramic transducer of the bottom distance sensor 2 to the reception of the echo information. Combining the propagation speed v3 of the sound wave in the current medium calculated by Formula 1, according to the speed-time-distance formula, the distance L2 from the bottom distance sensor 2 to the lower surface of the float can be obtained:

[0066]

[0067] Since the height of the float 3 is known, the liquid level height can be directly converted to obtain the liquid level height.

[0068] At the same time, the microprocessor MCU on the control board inputs an excitation signal with a fixed frequency and time to the ceramic transducer of the top distance sensor 1, making it emit ultrasonic waves with a fixed frequency towards the upper surface of the float in the liquid level tube. The sound wave is reflected by the upper reflecting surface 13 and then received by the ceramic transducer of the top distance sensor 1 to generate echo information. After being processed by the filter amplification circuit, the MCU cooperates with the high-performance TDC chip to calculate the sound wave flight time t1 from the start of ultrasonic wave emission by the ceramic transducer of the top distance sensor 1 to the reception of the echo. Combining the current system temperature T (°C) and the current humidity RH measured by the temperature-humidity probe, the speed V of sound propagation in the air 声速 Conforms to the following formula:

[0069]

[0070] P in Formula 4 w is the partial pressure P of water vapor in the air w = P 水蒸气饱和压强 ×RH%, T is the Celsius temperature, P is the atmospheric pressure; RH is the environmental relative humidity.

[0071] Combining Formula 4 and t1, according to the speed-time-distance formula, the distance from the top distance sensor 1 to the upper surface of the float 3 can be obtained:

[0072]

[0073] As shown in the attached Figure 3 figure, the distance from the top ranging sensor 1 to the bottom ranging sensor 2 is fixed at L, the distance from the surface of the bottom ranging sensor 2 to the bottom of the container is fixed at L0, the height of the float 3 is fixed at d, the height of the float 3 emerging from the liquid surface is d1, the height of the float 3 sinking into the liquid surface is d2, the finally output urea concentration is C, and the urea liquid level is H. The MCU obtains the actual data based on the known data and the measured parameters, and determines the correctness of each output data calculated based on the information output by multiple sensors. The true urea concentration measurement data is output.

[0074] Judging the correctness of the data calculated by multiple sensors includes the following situations:

[0075] 1. When the data of all probes are valid:

[0076] Combining formula 3 and formula 5 (formula 6), the following equation is satisfied:

[0077]

[0078] C = z1 (formula 8)

[0079] 2. When the concentration sensor fails and the other sensors are valid, the following equation is satisfied:

[0080] H = L - (L1 + d1) + L0 (formula 9)

[0081] Since the concentration sensor is invalid, it is impossible to determine the propagation speed v3 in the current medium, and thus it is impossible to determine L2 in formula 3. However, L2 can be deduced by combining L1 obtained from the top ranging sensor 1 with L, as follows:

[0082] L2 = L - L1 - d (formula 10)

[0083] Furthermore, the acoustic wave propagation speed at the current urea concentration is calculated

[0084]

[0085] Substituting the calculated v3 here and the temperature T (°C) measured by the temperature-humidity probe into formula 2, the urea concentration z1 can be obtained, and thus

[0086] C = z1 (formula 8)

[0087] 3. When the bottom ranging sensor 2 is invalid and the other sensors are valid; the following equation is satisfied:

[0088] H = L - (L1 + d1) + L0 (formula 13)

[0089] C = z1 (Equation 8)

[0090] 4. The ceramic transducer of the top ranging sensor 1 is invalid, and the other sensors are valid;

[0091] H = (L2 + d2) + L0 (Equation 15)

[0092] C = z1 (Equation 8)

[0093] Combining the above four situations, the device of the present invention combines the data of the four sensors. When any one of the sensors is damaged or interfered by adverse factors such as air bubbles, it can still ensure the accurate and effective output of the urea concentration and liquid level data during the vehicle driving process, and ensure the safe and reliable operation of the catalytic reaction of the SCR system.

[0094] Embodiment 3

[0095] As an alternative solution, the top ranging sensor 1 can be replaced with a laser rangefinder including a laser emission and reception component. At this time, the MCU controls the laser emission and reception component to emit laser with a fixed wavelength and time, and obtains the flight time t4 through the MCU processing and analysis component. Given the speed of light c, according to the speed-time-distance formula, the distance from the surface of the laser emission and reception component to the upper surface of the float 3 is:

[0096] L_1 = 1 / 2 ct4 (Equation 6)

[0097] At this time, the calculation method of Embodiment 2 above can still be used to judge the true urea concentration data and liquid level data when one sensor fails.

[0098] As shown in the appendix Figure 4 As shown, a liquid inlet is arranged at the bottom position of the liquid level tube. A filter screen 11 and a filter screen cover 12 are designed at the liquid inlet position. The filter screen cover 12 is detachable, which is convenient for later maintenance, cleaning and replacing the filter screen 11. The liquid inlet pipe is perforated around to increase the liquid inlet volume and speed, so that the height of the urea solution in the liquid level tube quickly returns to the same as the height of the urea in the urea tank, solving the disadvantage of slow response speed of the liquid level change inside and outside the liquid level tube. At the same time, the filter screen 11 can also play a certain filtering role for the impurities in the urea solution and some air bubbles in the liquid, avoiding the influence caused by air bubbles entering the liquid level tube.

[0099] After the residual air bubbles that enter through the filter screen 11 enter through the holes at the bottom of the liquid level tube, due to the small density of the air bubbles, they float up and are isolated by the anti-bubble bracket 10 at the bottom of the liquid level tube, which can prevent more air bubbles from entering, while the urea solution enters the liquid level tube through the holes at the bottom of the anti-bubble bracket 10.

[0100] For the urea quality detection device as described in the present utility model, the float 3 is made of rubber or plastic;

[0101] Preferably, the float 3 is made of nitrile rubber;

[0102] The outer shape of the side surface of the float 3 matches the internal configuration of the liquid level tube 7;

[0103] n ribs extending from the upper end to the lower end of the float 3 are arranged on the side surface of the float 3, where n≥2;

[0104] An upper reflecting sheet capable of reflecting the ranging signal of the top ranging sensor 1 is arranged on the top surface of the float 3;

[0105] A lower reflecting sheet capable of reflecting the ranging signal of the bottom ranging sensor 2 is arranged on the bottom surface of the float 3.

[0106] In the urea quality detection device as described in the present invention, both the top ranging sensor 1 and the bottom ranging sensor 2 are ultrasonic sensors;

[0107] The ultrasonic sensor includes a ceramic transducer.

[0108] In the urea quality detection device as described in the present invention, the top ranging sensor 1 is a laser rangefinder, and the laser rangefinder includes a laser emission and reception component;

[0109] The bottom ranging sensor 2 is an ultrasonic sensor, and the ultrasonic sensor includes a ceramic transducer.

[0110] In the urea quality detection device as described in the present invention, the MCU controls the laser emission and reception component to emit a laser ranging signal with a fixed wavelength, and the MCU receives and processes the ranging information output by the laser emission and reception component.

[0111] In the urea quality detection device as described in the present invention, the MCU inputs an excitation signal with a predetermined frequency and a predetermined time interval to the ceramic transducer, and the excitation signal drives the ceramic transducer to emit ultrasonic waves with a fixed frequency to the lower reflecting sheet and / or the upper reflecting sheet of the float 3. The ultrasonic waves are reflected by the reflecting sheet and then received by the corresponding ceramic transducer to generate echo information of the ultrasonic waves. The echo information is processed by a filter amplification circuit and then input to the MCU for arithmetic execution processing.

[0112] In the urea quality detection device as described in the present invention, in the urea solution tank, the concentration sensor is arranged at the lower end of the liquid level tube;

[0113] The concentration sensor includes a third sensor and a first reflecting sheet which are arranged opposite to each other at a predetermined distance; the third sensor is an ultrasonic sensor.

[0114] For the urea quality detection device according to the present utility model, the ultrasonic sensor includes a ceramic transducer. The MCU inputs an excitation signal with a predetermined frequency and a predetermined time interval to the ceramic transducer, so that the ceramic transducer emits ultrasonic waves with a predetermined frequency to the first reflector. After the ultrasonic waves are reflected by the first reflector, they are received by the ceramic transducer to generate echo information, and the echo information is input to the MCU for arithmetic processing after being processed by a filter amplification circuit.

[0115] For the urea quality detection device according to the present utility model, the temperature and humidity sensor measures the ambient temperature and humidity around the urea quality sensor, and the output information of the temperature-humidity sensor is input to the MCU for arithmetic processing.

[0116] For the urea quality detection device according to the present utility model, a liquid inlet and an anti-bubble support are arranged at the bottom position of the liquid level tube 7. A filter screen and a detachable filter screen cover are installed at the inlet of the liquid inlet. The urea solution enters the liquid level tube 7 through the liquid inlet and the holes at the bottom of the anti-bubble support in sequence.

[0117] The present utility model provides a solution of an ultrasonic liquid level detection with a float 3 in this scheme, which greatly improves the stability of data, solves the disadvantages that the traditional ultrasonic liquid level without a float 3 relies on the water surface to reflect sound waves, the data jitters or cannot be measured when the liquid level jitters or tilts, the data response is slow, and the liquid level of the reed switch scheme with a float 3 is discontinuous. In addition, due to the addition of the ceramic transducer or the laser emission and reception component of the top ranging sensor 1 for ranging in the air at the top of the liquid level tube 7, the ceramic transducer of the bottom ranging sensor 2 at the bottom of the liquid level tube 7 can be calibrated by using the fixed length of the liquid level tube 7 and the fixed length of the float 3 itself, improving the accuracy of the liquid level, and also solving the disadvantage that a single ultrasonic liquid level sensor inevitably has a blind area and cannot detect the actual liquid level.

[0118] In addition, the multi-sensor system of the present invention can ensure the output of accurate urea concentration and liquid level information in the case of any sensor failure.

[0119] Although the present utility model has been described in detail with general descriptions and specific embodiments above, based on the present utility model, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present utility model all fall within the scope of protection required by the present utility model.

Claims

1. A urea quality detection device for measuring liquid level and concentration through multiple sensors, characterized in that, The urea quality detection device includes: a liquid level tube, a float, a sensor group, an anti-bubble bracket and a control board; The control board contains a microprocessor MCU; The sensor group includes: a top ranging sensor, a bottom ranging sensor, a temperature-humidity sensor and a concentration sensor; The liquid level tube is arranged in the urea solution tank, and a float that floats up and down with the liquid level of the urea solution is installed in the liquid level tube; The top ranging sensor is installed at the top of the liquid level tube, and the bottom ranging sensor is installed at the bottom of the liquid level tube; The temperature-humidity sensor is installed in the upper section of the liquid level tube, and the concentration sensor is arranged at the bottom of the urea solution tank.

2. The urea quality detection device according to claim 1, characterized in that, The float is made of rubber or plastic; The outer shape of the side of the float matches the internal configuration of the liquid level tube; n ribs extending from the upper end to the lower end of the float are arranged on the side of the float, where n≥2; An upper reflector capable of reflecting the ranging signal of the top ranging sensor is arranged on the top surface of the float; A lower reflector capable of reflecting the ranging signal of the bottom ranging sensor is arranged on the bottom surface of the float.

3. The urea quality detection device according to claim 2, wherein Both the top ranging sensor and the bottom ranging sensor are ultrasonic sensors; The ultrasonic sensor includes a ceramic transducer.

4. The urea quality detection device according to claim 3, characterized in that, The top ranging sensor is a laser rangefinder, and the laser rangefinder includes a laser emission and reception component; The bottom ranging sensor is an ultrasonic sensor, and the ultrasonic sensor includes a ceramic transducer.

5. The urea quality detection device according to claim 4, characterized in that, The MCU controls the laser emission and reception component to emit a laser ranging signal with a fixed wavelength, and the MCU receives and processes the ranging information output by the laser emission and reception component.

6. The urea quality detection device according to claim 3 or 4, characterized in that, The MCU inputs an excitation signal with a predetermined frequency and a predetermined time interval to the ceramic transducer, and the excitation signal drives the ceramic transducer to emit ultrasonic waves with a fixed frequency to the lower reflector and / or the upper reflector of the float. After the ultrasonic waves are reflected by the reflector, they are received by the corresponding ceramic transducer and generate echo information of the ultrasonic waves. The echo information is processed by a filter amplification circuit and then input to the MCU for arithmetic execution processing.

7. The urea quality detection device according to claim 2, characterized in that, In the urea solution tank, the concentration sensor is arranged at the lower end of the liquid level tube; The concentration sensor includes a third sensor and a first reflector that are relatively arranged at a predetermined distance; the third sensor is an ultrasonic sensor.

8. The urea quality detection device according to claim 7, wherein, The ultrasonic sensor includes a ceramic transducer. The MCU inputs an excitation signal with a predetermined frequency and a predetermined time interval to the ceramic transducer, so that the ceramic transducer emits ultrasonic waves with a predetermined frequency to the first reflector. After the ultrasonic waves are reflected by the first reflector, they are received by the ceramic transducer to generate echo information. The echo information is processed by a filter amplification circuit and then input to the MCU for arithmetic processing.

9. The urea quality detection device according to claim 1, characterized in that, The temperature and humidity sensor measures the ambient temperature and humidity around the urea quality sensor, and the output information of the temperature-humidity sensor is input to the MCU for arithmetic processing.

10. The urea quality detection device according to claim 1, characterized in that, An inlet and an anti-bubble bracket are arranged at the bottom position of the liquid level tube. A filter screen and a detachable filter screen cover are installed at the inlet of the inlet. The urea solution enters the liquid level tube through the inlet and the hole positions at the bottom of the anti-bubble bracket in sequence.

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