Vehicle urea concentration detection device and vehicle urea concentration detection method

Abstract

The present invention relates to the field of vehicle technology, and discloses a vehicle urea concentration detection device and a vehicle urea concentration detection method. The density of the urea solution is calculated based on the actual liquid level of the urea solution at the location of the pressure detection unit and the pressure applied by the urea solution inside the urea tank to the bottom wall of the urea tank; the concentration of the urea solution is then calculated based on the density of the urea solution and the density of water. Even if bubbles are generated in the urea solution during vehicle driving or urea refilling, the amount of bubbles has little effect on the height of the urea solution and can be ignored. In addition, due to the high solubility of urea in water, the volume of the solution does not change much before and after the urea is dissolved in water. Compared with the effect of bubbles on the measurement results of the ultrasonic urea quality sensor, the change in the volume of the solution before and after the urea is dissolved in water can be ignored. Therefore, the calculated concentration of the urea solution has a high measurement accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicles, and in particular to a vehicle urea concentration detection device and a vehicle urea concentration detection method. Background Art

[0002] In existing technology, ultrasonic urea quality sensors are commonly used to detect urea concentration. Specifically, the urea concentration is calculated based on the ultrasonic voltage amplitude signal and echo time of the ultrasonic urea quality sensor. However, due to the varying attenuation of ultrasonic waves in different media, the detected ultrasonic voltage amplitude signal and echo time directly affect the final urea concentration when bubbles are present in urea. The more bubbles present and the larger their volume, the greater the impact on the measured urea concentration.

[0003] However, bubbles are inevitable in urea during actual application. For example, many bubbles will be generated during the urea filling process, and the vibration of the vehicle during operation will also generate many dense bubbles. Small bubbles are very easy to adhere to the ultrasonic urea quality sensor. Once a large number of small bubbles adhere to the ultrasonic urea quality sensor for a long time, it will directly lead to the distortion of the obtained urea concentration.

[0004] Therefore, a method for detecting urea concentration is urgently needed to solve the above technical problems. Summary of the Invention

[0005] The object of the present invention is to provide a vehicle urea concentration detection device and a vehicle urea concentration detection method, which can solve the problem of poor detection accuracy due to bubbles in the urea solution when using an ultrasonic urea quality sensor to detect urea concentration.

[0006] To achieve this object, the present invention provides a vehicle urea concentration detection device, comprising:

[0007] a pressure detection unit, used to obtain the pressure exerted by the urea solution inside the urea tank on the bottom wall of the urea tank;

[0008] a liquid level detection unit, configured to obtain the actual liquid level of the urea solution at the location of the pressure detection unit;

[0009] a urea solution density calculation module, electrically connected to the liquid level detection unit and the pressure detection unit, and configured to calculate the density of the urea solution based on the actual liquid level of the urea solution at the location of the pressure detection unit and the pressure applied by the urea solution in the urea tank to the bottom wall of the urea tank;

[0010] The urea solution concentration calculation module is electrically connected to the urea solution density calculation module, and the urea solution concentration calculation module is used to calculate the urea solution density according to the urea solution density ρ溶液 and the density of water ρ 水 Calculate the concentration C of urea solution 尿素浓度 ,

[0011] As a preferred technical solution of the above-mentioned vehicle urea concentration detection device, the liquid level detection unit includes:

[0012] A liquid level sensor, used to detect the liquid level h of the urea solution in the urea tank;

[0013] An inclination sensor is used to detect the inclination angle θ of the urea tank in the front-rear direction of the vehicle;

[0014] An acceleration acquisition module is used to obtain the acceleration a of the vehicle;

[0015] a liquid level calculation module, electrically connected to the liquid level sensor, the inclination sensor, and the acceleration acquisition module, for calculating the actual liquid level of the urea solution at the location of the pressure detection unit based on the liquid level h measured by the liquid level sensor, the inclination angle θ of the urea tank in the front-rear direction of the vehicle, and the acceleration a of the vehicle; and electrically connected to the urea solution density calculation module, for sending the actual liquid level of the urea solution at the location of the pressure detection unit to the urea solution density calculation module.

[0016] As a preferred technical solution of the above-mentioned vehicle urea concentration detection device, the liquid level sensor is a reed switch liquid level sensor.

[0017] As a preferred technical solution of the above-mentioned vehicle urea concentration detection device, the liquid level sensor is installed at the center of the bottom of the urea tank;

[0018] The pressure detection unit is installed at the center of the bottom of the urea tank, or the pressure detection unit is installed at the bottom of the urea tank and is located directly in front of or directly behind the center of the bottom of the urea tank.

[0019] In a second aspect, the present invention further provides a method for detecting urea concentration in a vehicle, which is used in the vehicle urea concentration detection device described in any of the above schemes. The method for detecting urea concentration in a vehicle comprises the following steps:

[0020] Obtain the actual liquid level of the urea solution at the location of the pressure detection unit in the urea tank and the pressure at the center of the bottom of the urea tank, and calculate the density ρ of the urea solution based on the actual liquid level and the pressure 溶液 ;

[0021] Calculate the concentration of urea solution C according to the density of the urea solution and the density of water尿素浓度 , Among them, ρ 水 Indicates the density of water.

[0022] As a preferred technical solution of the above-mentioned vehicle urea concentration detection method, the actual liquid level height at the position of the pressure detection unit in the urea tank is obtained according to the following steps:

[0023] obtaining an inclination angle θ of the urea tank in the front-rear direction of the vehicle, a liquid level height h measured by a liquid level sensor of the liquid level detection unit, and an acceleration a during vehicle driving, and determining a vehicle driving mode based on the inclination angle θ, the liquid level height h, and the acceleration a;

[0024] The actual liquid level H of the urea solution is calculated according to the determined vehicle driving mode, the inclination angle θ, the liquid level h, and the acceleration a.

[0025] As a preferred technical solution of the above-mentioned vehicle urea concentration detection method, when the liquid level sensor of the liquid level detection unit is installed at the center of the bottom of the urea tank, and the pressure detection unit is installed at the center of the bottom of the urea tank, the vehicle driving mode includes a flat ground driving mode, a constant speed uphill and downhill mode, an uphill acceleration and downhill deceleration mode, and an uphill deceleration and downhill acceleration mode;

[0026] When the vehicle is in the flat ground driving mode, the actual liquid level of the urea solution is H=h;

[0027] When the vehicle is in the uniform speed uphill and downhill mode, H = h × cos θ;

[0028] When the vehicle is in the uphill acceleration and downhill deceleration mode, H = h × cosθ - h × sinθ × a / g;

[0029] When the vehicle is in the uphill deceleration and downhill acceleration mode, H = h × cosθ + h × sinθ × a / g;

[0030] Wherein, h represents the liquid level measured by the liquid level sensor, θ represents the inclination angle of the vehicle in the front and rear directions, a represents the acceleration of the vehicle, and g represents the acceleration due to gravity.

[0031] As a preferred technical solution of the above-mentioned vehicle urea concentration detection method, the inclination angle θ of the urea tank in the front-rear direction of the vehicle and the acceleration a of the vehicle when the vehicle is traveling are obtained, and the vehicle driving mode is determined according to the inclination angle θ and the acceleration a, including:

[0032] When the inclination angle θ is less than a preset inclination angle, the vehicle is in the flat ground driving mode;

[0033] When the inclination angle θ is not less than the preset inclination angle and the acceleration a is within the preset acceleration range, the vehicle is in the uniform speed uphill and downhill mode;

[0034] When the inclination angle θ is not less than the preset inclination angle and the acceleration a is not within the preset acceleration range, the vehicle is in the uphill acceleration and downhill deceleration mode or the uphill deceleration and downhill acceleration mode.

[0035] As a preferred technical solution of the above-mentioned vehicle urea concentration detection method, if a reed switch liquid level sensor is used to detect the liquid level of the urea solution in the urea tank; before determining the vehicle driving mode according to the inclination angle θ, the liquid level h and the acceleration a, the following steps are also included:

[0036] It is determined whether the reed switch liquid level sensor is stuck. If the reed switch liquid level sensor is not stuck, the vehicle driving mode is determined according to the inclination angle θ, the liquid level height h and the acceleration a.

[0037] As a preferred technical solution of the above-mentioned vehicle urea concentration detection method, when it is confirmed that the reed switch liquid level sensor is not stuck, the liquid level height currently detected by the reed switch liquid level sensor is recorded;

[0038] Next time when it is confirmed that the reed switch liquid level sensor is not stuck, the recorded liquid level height is updated;

[0039] When the reed switch liquid level sensor is stuck, the vehicle driving mode is determined according to the inclination angle θ, the recorded liquid level height and the acceleration a.

[0040] Beneficial effects of the present invention: The vehicle urea concentration detection device and vehicle urea concentration detection method provided by the present invention use a pressure detection unit to detect the pressure applied by the urea solution inside the urea tank to the bottom wall of the urea tank, and use a liquid level detection unit to obtain the actual liquid level of the urea solution at the position where the pressure detection unit is located in the urea tank; then, the density of the urea solution is calculated based on the actual liquid level of the urea solution at the position where the pressure detection unit is located and the pressure applied by the urea solution inside the urea tank to the bottom wall of the urea tank; and then, the concentration of the urea solution is calculated based on the density of the urea solution and the density of water.

[0041] Even if bubbles are generated in the urea solution while the vehicle is driving or adding urea, the amount of bubbles has little effect on the height of the urea solution and can be ignored. In addition, due to the high solubility of urea in water, the volume of the solution does not change much before and after the urea is dissolved in water. Compared with the effect of bubbles on the measurement results of the ultrasonic urea quality sensor, the change in the solution volume before and after the urea is dissolved in water can be ignored. Therefore, the calculated concentration of the urea solution has a higher measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in describing the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without any creative work.

[0043] Figure 1 1 is a schematic diagram of a urea concentration detection device provided by an embodiment of the present invention;

[0044] Figure 2 In the embodiment of the present invention, the pressure sensor is installed at the center of the bottom of the urea tank, and the reed switch liquid level sensor is installed at the center of the bottom of the urea tank, and the state diagram of the urea tank when the vehicle is traveling at a constant speed, accelerating, and decelerating on flat ground;

[0045] Figure 3 This is a state diagram of the urea tank when a vehicle is traveling at a constant speed on a slope, when the pressure sensor is installed at the center of the bottom of the urea tank and the reed switch liquid level sensor is installed at the center of the bottom of the urea tank in an embodiment of the present invention;

[0046] Figure 4 This is a state diagram of the urea tank when a vehicle accelerates uphill or decelerates downhill, when the pressure sensor is installed at the center of the bottom of the urea tank and the reed switch liquid level sensor is installed at the center of the bottom of the urea tank in an embodiment of the present invention;

[0047] Figure 5 This is a state diagram of the urea tank when a vehicle is decelerating uphill or accelerating downhill, when the pressure sensor is installed at the center of the bottom of the urea tank and the reed switch liquid level sensor is installed at the center of the bottom of the urea tank in an embodiment of the present invention;

[0048] Figure 6 This is a state diagram of the urea tank when the vehicle is traveling on level ground at a constant speed, accelerating, and decelerating, respectively, when the pressure sensor is offset forward and not offset left or right, and the reed switch liquid level sensor is installed at the center of the bottom of the urea tank in an embodiment of the present invention;

[0049] Figure 7 This is a state diagram of the urea tank when a vehicle is traveling uphill at a constant speed, in an embodiment of the present invention, when the pressure sensor is biased forward and not biased left or right, and the reed switch liquid level sensor is installed at the center of the bottom of the urea tank;

[0050] Figure 8This is a state diagram of the urea tank when a vehicle is traveling downhill at a constant speed, in an embodiment of the present invention, when the pressure sensor is biased forward and not biased left or right, and the reed switch liquid level sensor is installed at the center of the bottom of the urea tank;

[0051] Figure 9 This is a state diagram of the urea tank when a vehicle accelerates uphill, in an embodiment of the present invention, when the pressure sensor is offset forward and not offset left or right, and the reed switch liquid level sensor is installed at the center of the bottom of the urea tank;

[0052] Figure 10 This is a state diagram of the urea tank when a vehicle is decelerating while driving uphill, when the pressure sensor is offset forward and not offset left or right, and the reed switch liquid level sensor is installed at the center of the bottom of the urea tank in an embodiment of the present invention;

[0053] Figure 11 This is a state diagram of the urea tank when a vehicle is accelerating downhill, in an embodiment of the present invention, when the pressure sensor is biased forward and not biased left or right, and the reed switch liquid level sensor is installed at the center of the bottom of the urea tank;

[0054] Figure 12 This is a state diagram of the urea tank when a vehicle is decelerating downhill, in an embodiment of the present invention, when the pressure sensor is biased forward and not biased left or right, and the reed switch liquid level sensor is installed at the center of the bottom of the urea tank;

[0055] Figure 13 The following are state diagrams of the urea tank when a vehicle is traveling on level ground at a constant speed, acceleration, and deceleration, respectively, when the pressure sensor is offset backward and not offset left or right, and the reed switch liquid level sensor is installed at the center of the bottom of the urea tank in an embodiment of the present invention;

[0056] Figure 14 This is a main flow chart of a method for detecting urea concentration in a vehicle provided by an embodiment of the present invention;

[0057] Figure 15 It is a detailed flow chart of the vehicle urea concentration detection method provided by an embodiment of the present invention.

[0058] In the picture:

[0059] 1. Liquid level detection unit; 11. Inclination sensor; 12. Liquid level sensor; 13. Liquid level height calculation module; 14. Acceleration acquisition module; 2. Vehicle controller; 3. Urea solution concentration calculation module; 4. Urea solution density calculation module; 5. Pressure detection unit; 6. Urea tank. DETAILED DESCRIPTION

[0060] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0061] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0062] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0063] In the description of this embodiment, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meanings.

[0064] This embodiment provides a vehicle urea concentration detection device, such as Figure 1As shown, the vehicle urea concentration detection device includes a liquid level detection unit 1, a pressure detection unit 5, a urea solution density calculation module 4 and a urea solution concentration calculation module 3, wherein the pressure detection unit 5 is used to obtain the pressure applied by the urea solution inside the urea tank 6 to the bottom wall of the urea tank 6, and the liquid level detection unit 1 is used to obtain the actual liquid level of the urea solution at the position where the pressure detection unit 5 is located; the urea solution density calculation module 4 is electrically connected to the liquid level detection unit 1 and the pressure detection unit 5, and is used to calculate the density of the urea solution according to the actual liquid level of the urea solution at the position where the pressure detection unit 5 is located and the pressure applied by the urea solution inside the urea tank 6 to the bottom wall of the urea tank 6; the urea solution concentration calculation module 3 is electrically connected to the urea solution density calculation module 4, and is used to calculate the density of the urea solution according to the density ρ of the urea solution. 溶液 and the density of water ρ 水 Calculate the concentration C of urea solution 尿素浓度 ,

[0065] The vehicle urea concentration detection device provided in this embodiment uses a pressure detection unit 5 to detect the pressure exerted by the urea solution inside the urea tank 6 on the bottom wall of the urea tank 6, and uses a liquid level detection unit 1 to detect the actual liquid level of the urea solution at the location of the pressure detection unit 5 inside the urea tank 6. The density of the urea solution is then calculated based on the actual liquid level of the urea solution at the location of the pressure detection unit 5 and the pressure exerted by the urea solution inside the urea tank 6 on the bottom wall of the urea tank 6. The concentration of the urea solution is then calculated based on the density of the urea solution and the density of water. Even if bubbles are generated in the urea solution during vehicle driving or urea refilling, the amount of bubbles has a negligible effect on the height h of the urea solution. Furthermore, due to the high solubility of urea in water, the volume of the solution does not change much before and after dissolving the urea in water. Compared to the effect of bubbles on the measurement results of the ultrasonic urea quality sensor, the change in the volume of the solution before and after dissolving the urea in water is negligible. Therefore, the urea solution concentration calculated using this method has a high measurement accuracy.

[0066] In this embodiment, the density of the urea solution is Wherein, P represents the pressure exerted by the urea solution inside the urea tank 6 on the bottom wall of the urea tank 6; g represents a constant, which is the ratio of gravity to mass, g = 9.8 N / kg; and H represents the vertical distance between the location of the pressure detection unit 5 and the liquid level of the urea solution in the urea tank 6. In this embodiment, the pressure detection unit 5 is a pressure sensor.

[0067] In this embodiment, the concentration of urea solution C 尿素浓度 The calculation method includes the following steps:

[0068] Total mass of solution M 总=ρ 溶液 ×V 溶液 =M 水 +M 尿素 , M 水 =ρ 水 ×V 溶液 , Among them, V 溶液 Represents the total volume of the mixed solution of urea and water, M 水 Indicates the mass of water in urea solution, M 尿素 represents the mass of urea in the urea solution, ρ 水 Indicates the density of water.

[0069] Optionally, the pressure detection unit 5 is located at the center of the bottom of the urea tank 6. Therefore, when the urea tank 6 tilts due to the vehicle tilting left or right, the detection result of the pressure detection unit 5 is not affected. That is, when the amount of urea solution in the urea tank 6 is the same, the detection result of the pressure detection unit 5 when the urea tank 6 is tilted is the same as the detection result of the pressure detection unit 5 when the urea tank 6 is horizontal. It should be noted that the urea tank 6 is symmetrical about a first plane and a second plane, wherein the first plane refers to a plane perpendicular to the front-to-back direction of the vehicle, and the second plane refers to a plane perpendicular to the left-to-right direction of the vehicle. The center of the bottom of the urea tank 6 refers to the area surrounded by a point in the urea tank 6 that is spaced a preset length from the center, centered at the intersection of the first plane, the second plane, and the inner bottom wall of the urea tank 6, or the area surrounded by two planes 1 and 2 that are spaced a preset length from the first plane, two planes 2 that are spaced a preset length from the second plane, and the inner bottom wall of the urea tank 6. The preset length is a known value determined based on actual needs.

[0070] Furthermore, considering the impact of the vehicle going uphill or downhill on the measurement results of the liquid level detection unit 1, the liquid level detection unit 1 includes a liquid level sensor 12, a tilt sensor 11, an acceleration acquisition module 14, and a liquid level height calculation module 13, wherein the liquid level sensor 12 is used to detect the liquid level h of the urea solution in the urea tank 6; the tilt sensor 11 is used to detect the tilt angle θ of the urea tank 6 in the front-rear direction of the vehicle; the acceleration acquisition module 14 is used to obtain the acceleration a of the vehicle; the liquid level height calculation module 13 is electrically connected to the liquid level sensor 12, the tilt sensor 11, and the acceleration acquisition module 14, and is used to calculate the actual liquid level H of the urea solution at the location of the pressure sensor based on the liquid level h, the acceleration a, and the tilt angle θ; the liquid level height calculation module 13 is electrically connected to the urea solution density calculation module 4, and is used to send the actual liquid level H of the urea solution at the location of the pressure sensor to the urea solution density calculation module 4.

[0071] In this embodiment, the liquid level sensor 12 is a reed switch liquid level sensor. In order to improve the accuracy of the measurement results of the reed switch liquid level sensor, the liquid level sensor 12 is installed at the center position of the bottom of the urea tank 6. At this time, the liquid level inclination caused by vehicle acceleration, deceleration, and uphill and downhill driving will not affect the liquid level height measured by the liquid level sensor 12.

[0072] The pressure sensor is mounted on the bottom wall of the urea tank 6. There are various specific mounting positions for the pressure sensor, such as the center of the bottom wall of the urea tank 6, or offset front-to-back and not offset left-to-right relative to the center of the bottom wall of the urea tank 6, or not offset front-to-back and offset left-to-right relative to the center of the bottom wall of the urea tank 6, or offset front-to-back and offset left-to-right relative to the center of the bottom wall of the urea tank 6. Considering that when the pressure sensor is offset left-to-right relative to the center of the bottom wall of the urea tank 6, the liquid level will also tilt when the vehicle tilts left-to-right, which will also affect the measurement results of the pressure sensor and greatly increase the inaccuracy of the pressure sensor's measurement results. For this reason, when the pressure sensor is usually installed, it is required that the pressure sensor is not offset left-to-right relative to the center of the bottom wall of the urea tank 6.

[0073] Preferably, the pressure sensor is installed at the center of the bottom wall of the urea tank 6. When the pressure sensor and the liquid level sensor 12 are installed at the center of the bottom wall of the urea tank 6, the position of the pressure sensor and the actual liquid level H of the urea solution in the urea tank 6 may have the following situations depending on the driving conditions of the vehicle.

[0074] In the first case, the vehicle is moving at a constant speed on flat ground (see Figure 2 Figure (1)), or accelerated (see Figure 2 Figure (2) in the figure), or slow down (see Figure 2 (3) in FIG), at this time H = h, h represents the liquid level height measured by the liquid level sensor 12. That is, when the vehicle is traveling on flat ground, the measurement result of the pressure sensor will not be affected regardless of whether the vehicle is accelerating, decelerating or traveling at a constant speed.

[0075] In the second case, when the vehicle is moving up and down the slope at a constant speed, Figure 3 As shown, H = h × cos θ, where θ represents the tilt angle of the vehicle in the front-rear direction.

[0076] In the third case, when the vehicle is accelerating uphill or decelerating downhill, Figure 4As shown, h1 = h × cosθ, Δh = h × sinθ × tanγ, and H = h1 - Δh; where γ is the inclination angle of the urea solution surface relative to the horizontal plane caused by vehicle acceleration or deceleration. Assuming there is a mass m on the liquid surface at the position corresponding to the reed switch liquid level sensor, the gravity G of mass m is decomposed to obtain F1 and F2, where F2 = ma = G × tanγ and G = mg. From this, we can calculate the inclination angle γ = arctan(a / g) caused by vehicle acceleration. From this, we can deduce H = h × cosθ - h × sinθ × a / g, where a represents the vehicle's acceleration and g represents the acceleration due to gravity.

[0077] The fourth situation is when the vehicle is accelerating downhill or decelerating uphill. Figure 5 As shown, referring to the second case, it can be deduced that H = h × cosθ + h × sinθ × a / g.

[0078] In some other embodiments, when the pressure sensor is biased forward and not biased left or right, that is, when the pressure sensor is located directly in front of the center of the bottom of the urea tank 6, and the reed switch liquid level sensor is installed at the center of the bottom of the urea tank 6, depending on the driving conditions of the vehicle, the vertical distance H between the position of the pressure sensor and the liquid level of the urea solution in the urea tank 6 has the following situations.

[0079] (1) The vehicle is traveling at a constant speed on flat ground, such as Figure 6 As shown in the middle figure (1), at this time H = h.

[0080] (2) The vehicle accelerates on flat ground, such as Figure 6 As shown in Figure (2), H = h - △h, △h = d × tanγ, γ = a / g, from which we can deduce H = hd × a / g.

[0081] (3) When the vehicle is decelerating on flat ground, Figure 6 As shown in Figure (3), H = h + △h, △h = d × tanγ, from which we can deduce H = h + d × a / g.

[0082] (4) When the vehicle is traveling uphill at a constant speed, Figure 7 As shown, H = h1-△h, h1 = h / cosθ, △h = d1×tanθ, d1 = (d+d2)×cosθ, d2 = h×tanθ, from which H = h / cosθ-(d+h×tanθ)×cosθ×tanθ can be calculated, where d represents the distance that the pressure sensor deviates from the center position of the bottom of the urea tank 6 along the front-rear direction of the vehicle.

[0083] (5) When the vehicle is traveling downhill at a constant speed, Figure 8As shown, H = (Δh + h) × cosθ, Δh = d × tanθ, from which we can deduce H = (h + d × tanθ) × cosθ.

[0084] (6) When the vehicle accelerates uphill, Figure 9 As shown, H = h1-△h, h1 = h2×cosθ, h2 = h-h3, h3 = d×tanθ; △h = d3×tanγ, d3 = d1+d2, d1 = d / cosθ, d2 = h2×sinθ; the inclination angle γ of the liquid surface caused by vehicle acceleration = arctan(a / g), from which it can be inferred that H = (hd×tanθ)×cosθ-(a / g)×(d / cosθ+(hd×tanθ)×sinθ).

[0085] (7) When the vehicle is decelerating while driving uphill, Figure 10 As shown, H = h1 + Δh, h1 = h2 × cosθ, h2 = h - h3, h3 = d × tanθ; Δh = d3 × tan(γ + θ), d3 = d1 + d2, d1 = d / cosθ, d2 = h2 × tanθ, and the inclination angle γ of the liquid surface due to vehicle acceleration = arctan(a / g). From this, we can deduce H = (hd × tanθ) × cosθ + tan(γ + θ) × (d / cosθ + (hd × tanθ) × tanθ).

[0086] (8) When the vehicle is accelerating downhill, Figure 11 As shown, H = h1-△h, h1 = h2×cosθ, h2 = h+h3, h3 = d×tanθ, △h = d2×tanγ, d2 = d3-d1, d3 = d×cosθ, d1 = h2×sinθ, the inclination angle γ of the liquid surface caused by vehicle acceleration = arctan(a / g), from which it can be inferred that H = (h+d×tanθ)×cosθ-(d×cosθ-(h+d×tanθ)×sinθ)×a / g.

[0087] (9) When the vehicle is decelerating while driving downhill, Figure 12 As shown, H = h1 + △h, h1 = h2 × cosθ, h2 = h + h3, h3 = d × tanθ; △h = d2 × tanγ, d2 = d3 - d1, d3 = d × cosθ, d1 = h2 × sinθ, the inclination angle γ of the liquid surface due to vehicle acceleration = arctan (a / g), from which it can be inferred that H = (h + d × tanθ) × cosθ + (d × cosθ - (h + d × tanθ) × sinθ) × a / g.

[0088] In some other embodiments, when the pressure sensor is offset backward and not offset left or right, that is, when the pressure sensor is located directly in front of the center of the bottom of the urea tank 6, and the reed switch liquid level sensor is installed at the center of the bottom of the urea tank 6, depending on the driving conditions of the vehicle, the vertical distance H between the position of the pressure sensor and the liquid level of the urea solution in the urea tank 6 has the following situations.

[0089] (1) The vehicle is traveling at a constant speed on flat ground, such as Figure 13 As shown in Figure (1), at this time H = h.

[0090] (2) The vehicle accelerates on flat ground, such as Figure 13 As shown in Figure (2), H = h + △h, △h = d × tanγ, γ = a / g, from which we can deduce H = h + d × a / g.

[0091] (3) When the vehicle is decelerating on flat ground, Figure 13 As shown in Figure (3), H = h-△h, △h = d×tanγ, from which we can deduce H = hd×a / g.

[0092] (4) When the vehicle is moving uphill at a constant speed, Figure 8 The situation shown is similar, H = (h + d × tan θ) × cos θ.

[0093] (5) When the vehicle is moving downhill at a constant speed, Figure 7 The situation shown is similar, H = h / cosθ-(d+h×tanθ)×cosθ×tanθ.

[0094] (6) When the vehicle accelerates uphill, Figure 12 The case shown is similar, H = (h + d × tan θ) × cos θ + (d × cos θ - (h + d × tan θ) × sin θ) × a / g.

[0095] (7) When the vehicle decelerates and goes uphill, Figure 11 The case shown is similar, H = (h + d × tan θ) × cos θ - (d × cos θ - (h + d × tan θ) × sin θ) × a / g.

[0096] (8) When the vehicle accelerates downhill, Figure 10 The case shown is similar, H = (hd × tanθ) × cosθ + tan(γ + θ) × (d / cosθ + (hd × tanθ) × tanθ.

[0097] (9) When the vehicle decelerates downhill, Figure 9 The case shown is similar, H = (hd×tanθ)×cosθ-(a / g)×(d / cosθ+(hd×tanθ)×sinθ).

[0098] In other embodiments, the corresponding relationship among the measured value of the pressure sensor, the distance from the installation position of the pressure sensor to the center position of the bottom of the urea tank 6, the inclination angle of the urea tank 6, the acceleration of the vehicle, and the actual pressure applied by the urea solution inside the urea tank 6 to the bottom wall of the urea tank 6 can be determined by repeated tests. The actual pressure applied by the urea solution inside the urea tank 6 to the bottom wall of the urea tank 6 corresponding to the measured value of the pressure sensor, the distance from the installation position of the pressure sensor to the center position of the bottom of the urea tank 6, the inclination angle of the urea tank 6, and the acceleration of the vehicle can be queried.

[0099] The inclination sensor 11 is an existing sensor on the vehicle, and the acceleration acquisition module 14 is also an existing structure on the vehicle. The inclination sensor 11 and the acceleration acquisition module 14 are electrically connected to the vehicle controller 2 of the vehicle. In order to simplify the modification of the vehicle, the vehicle controller 2 is electrically connected to the liquid level height calculation module 13. The vehicle controller 2 can send the measurement signal of the inclination sensor 11 and the acceleration signal of the acceleration acquisition module 14 to the liquid level height calculation module 13.

[0100] The urea solution concentration calculation module 3 is electrically connected to the vehicle controller 2 . The urea solution concentration calculation module 3 can send the calculated concentration of the urea solution to the vehicle controller 2 for vehicle post-processing control.

[0101] Furthermore, reed switch liquid level sensors often experience stuckness during liquid level measurement. Therefore, before calculating the actual liquid level H of the urea solution at the location of the pressure sensor based on the liquid level h, acceleration a, and tilt angle θ, the method further includes the following steps: determining whether the reed switch liquid level sensor is stuck; if the reed switch liquid level sensor is not stuck, calculating the actual liquid level H of the urea solution at the location of the pressure sensor based on the liquid level h, acceleration a, and tilt angle θ.

[0102] Furthermore, in order to prevent the reed switch liquid level sensor from getting stuck during measurement, thereby preventing it from affecting the measurement of the urea solution concentration, when it is confirmed that the reed switch liquid level sensor is not stuck, the liquid level height h currently detected by the reed switch liquid level sensor is recorded; the next time it is confirmed that the reed switch liquid level sensor is not stuck, the recorded liquid level height h is updated; when the reed switch liquid level sensor is stuck, the recorded liquid level height h, acceleration a, and inclination angle θ are used to calculate the actual liquid level height H of the urea solution at the location of the pressure sensor.

[0103] Since the time interval between two consecutive detections of the reed switch liquid level sensor is very short, the actual urea solution consumed during this time interval is also very small, and its impact on the actual liquid level is very small and can be ignored. Therefore, when confirming that the reed switch liquid level sensor is not stuck, the actual urea solution consumed between two consecutive detections of the reed switch liquid level sensor is ignored.

[0104] It should be noted that reed switch liquid level sensors are commonly used as liquid level measurement tools. When the magnetic float outside the reed switch rises and falls with the liquid level, the reed switches located at the liquid surface within the reed switch's main conduit are sequentially energized, causing the resistance of a precision resistor to change. A conversion circuit module then converts this resistance into a 4mA to 20mA current output, thereby measuring the current liquid level. Determining whether a reed switch liquid level sensor is stuck is conventional in the art and will not be detailed here.

[0105] like Figure 14 As shown, this embodiment also provides a vehicle urea concentration detection method, which is used in the above-mentioned vehicle urea concentration detection device. The vehicle urea concentration detection method includes the following steps:

[0106] S11, obtain the actual liquid level of the urea solution at the location of the pressure detection unit 5 in the urea tank 6, and the pressure at the center of the bottom of the urea tank 6, and calculate the density ρ of the urea solution based on the actual liquid level and pressure 溶液 ;

[0107] S12. Calculate the urea solution concentration C based on the density of the urea solution and the density of water. 尿素浓度 , Among them, ρ 水 Indicates the density of water.

[0108] Figure 15 This is a detailed flow chart of the vehicle urea concentration detection method provided in this embodiment. Taking the liquid level sensor 12 as a reed switch liquid level sensor, and the liquid level sensor 12 and the pressure sensor are both installed at the center position of the bottom of the urea tank 6 as an example, the following is combined with Figure 15 The vehicle urea concentration detection method provided in this embodiment is briefly introduced.

[0109] S21, determine whether the reed switch liquid level sensor is stuck. If so, retrieve the recorded liquid level height h and then execute S23. If not, execute S22;

[0110] S22, obtaining the liquid level height h measured by the reed switch liquid level sensor, updating the recorded liquid level height h, and executing S23 at the same time;

[0111] S23, obtaining the inclination angle θ of the urea tank 6 in the front-rear direction of the vehicle and the acceleration a of the vehicle when the vehicle is traveling, and determining the vehicle driving mode according to the inclination angle θ and the acceleration a;

[0112] S24, calculating the actual liquid level H of the urea solution according to the determined vehicle driving mode, liquid level h, inclination angle θ, and acceleration a;

[0113] S25, obtain the pressure at the center of the bottom of the urea tank 6, and calculate the density ρ of the urea solution based on the actual liquid level and pressure 溶液 ;

[0114] S26, according to the density of urea solution ρ 溶液 and the density of water ρ 水 Calculate the concentration C of urea solution 尿素浓度 ,

[0115] In this embodiment, according to the inclination angle θ and the acceleration a, the vehicle driving modes are divided into four types, namely, flat ground driving mode, uniform speed uphill and downhill mode, uphill acceleration and downhill deceleration mode, uphill deceleration and downhill acceleration mode. Among them, the flat ground driving mode corresponds to the first case mentioned above, the uniform speed uphill and downhill mode corresponds to the second case mentioned above, the uphill acceleration and downhill deceleration mode corresponds to the third case mentioned above, and the uphill deceleration and downhill acceleration mode corresponds to the fourth case mentioned above. The actual liquid level H of the urea solution at the location of the pressure detection unit 5 can be calculated according to the corresponding formulas.

[0116] Considering that when the vehicle's front-to-back tilt angle is small, the pressure sensor's measurement results are less affected. To simplify the calculation process, the pressure sensor's measurement results can be ignored when the vehicle's front-to-back tilt angle is small. Specifically, the tilt angle θ of the urea tank 6 in the vehicle's front-to-back direction and the acceleration a of the vehicle during driving are obtained, and the vehicle's driving mode is determined based on the tilt angle θ and the acceleration a, including the following steps:

[0117] S231, determining whether the inclination angle is less than a preset inclination angle, if so, the vehicle is in a flat ground driving mode, and then executing S24; if not, executing S232;

[0118] S232: Determine whether the vehicle acceleration is within a preset acceleration range. If so, the vehicle is in a uniform uphill and downhill mode, and then execute S24; if not, execute S233;

[0119] S233, determine whether the vehicle is in the uphill acceleration and downhill deceleration mode, if so, execute S24; if not, the vehicle is in the uphill deceleration and downhill acceleration mode, execute S24.

[0120] As for how to determine whether the vehicle is accelerating uphill, decelerating downhill, decelerating uphill, or accelerating downhill, it is the existing technology in this field and will not be described in detail here.

[0121] The preset inclination angle is a known value determined through repeated testing. When the absolute value of the inclination angle θ is less than the preset inclination angle, it is assumed that the inclination angle has a very small effect on the actual liquid level and has little impact on the calculated urea solution concentration. The acceleration range fluctuating around zero is recorded as the preset acceleration range. The preset acceleration range can be determined through repeated testing and is an acceleration range within which the actual urea solution level has a negligible effect.

[0122] Furthermore, the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments herein, and that various obvious changes, readjustments, and substitutions are possible for those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A vehicle urea concentration detection method is implemented using a vehicle urea concentration detection device, characterized in that: The vehicle urea concentration detection device includes: A pressure detection unit (5) for obtaining the pressure exerted by the urea solution inside the urea tank (6) on the bottom wall of the urea tank (6); A liquid level detection unit (1) is used to obtain the actual liquid level height of the urea solution at the location where the pressure detection unit (5) is located; a urea solution density calculation module (4) electrically connected to the liquid level detection unit (1) and the pressure detection unit (5), the urea solution density calculation module (4) being used to calculate the density of the urea solution based on the actual liquid level of the urea solution at the location of the pressure detection unit (5) and the pressure applied by the urea solution inside the urea tank (6) to the bottom wall of the urea tank (6); A urea solution concentration calculation module (3) is electrically connected to the urea solution density calculation module (4), and the urea solution concentration calculation module (3) is used to calculate the urea solution density according to the urea solution density ρ 溶液 and the density of water ρ 水 Calculate the concentration C of urea solution 尿素浓度 , The liquid level detection unit (1) comprises: A liquid level sensor (12) for detecting a liquid level height h of the urea solution in the urea tank (6); An inclination sensor (11) is used to detect an inclination angle θ of the urea tank (6) in the front-rear direction of the vehicle; An acceleration acquisition module (14) is used to acquire the acceleration a of the vehicle; A liquid level height calculation module (13) is electrically connected to the liquid level sensor (12), the tilt sensor (11), and the acceleration acquisition module (14). The liquid level height calculation module (13) is used to calculate the actual liquid level height of the urea solution at the location of the pressure detection unit (5) based on the liquid level height h measured by the liquid level sensor (12), the tilt angle θ of the urea tank (6) in the front-rear direction of the vehicle, and the acceleration a of the vehicle. The liquid level height calculation module (13) is electrically connected to the urea solution density calculation module (4). The liquid level height calculation module (13) is used to send the actual liquid level height of the urea solution at the location of the pressure detection unit (5) to the urea solution density calculation module (4). The vehicle urea concentration detection method comprises the following steps: Obtain the actual liquid level of the urea solution at the location of the pressure detection unit (5) in the urea tank (6) and the pressure at the center of the bottom of the urea tank (6), and calculate the density ρ of the urea solution based on the actual liquid level and the pressure 溶液 ; Calculate the concentration of urea solution C according to the density of the urea solution and the density of water 尿素浓度 , Among them, ρ 水 Indicates the density of water; The actual liquid level height of the urea solution at the location of the pressure detection unit (5) in the urea tank (6) is obtained according to the following steps: Obtaining an inclination angle θ of the urea tank (6) in the front-rear direction of the vehicle, a liquid level height h measured by a liquid level sensor (12) of the liquid level detection unit (1), and an acceleration a during vehicle travel, and determining a vehicle travel mode based on the inclination angle θ, the liquid level height h, and the acceleration a; Calculating the actual liquid level H of the urea solution according to the determined vehicle driving mode, inclination angle θ, liquid level h, and acceleration a; When the liquid level sensor (12) of the liquid level detection unit (1) is installed at the center of the bottom of the urea tank (6), and the pressure detection unit (5) is installed at the center of the bottom of the urea tank (6), the vehicle driving modes include a flat ground driving mode, a constant speed uphill and downhill mode, an uphill acceleration and downhill deceleration mode, and an uphill deceleration and downhill acceleration mode; When the vehicle is in the flat ground driving mode, the actual liquid level of the urea solution is H=h; When the vehicle is in the uniform speed uphill and downhill mode, H = h × cos θ; When the vehicle is in the uphill acceleration and downhill deceleration mode, H = h × cosθ - h × sinθ × a / g; When the vehicle is in the uphill deceleration and downhill acceleration mode, H = h × cosθ + h × sinθ × a / g; Wherein, h represents the liquid level height measured by the liquid level sensor (12), θ represents the inclination angle of the vehicle in the front-back direction, a represents the acceleration of the vehicle, and g represents the acceleration due to gravity.

2. The vehicle urea concentration detection method according to claim 1, characterized in that: The liquid level sensor (12) is a reed switch liquid level sensor.

3. The vehicle urea concentration detection method according to claim 2, characterized in that: The liquid level sensor (12) is installed at the center of the bottom of the urea tank (6); The pressure detection unit (5) is installed at the center of the bottom of the urea tank (6), or the pressure detection unit (5) is installed at the bottom of the urea tank (6) and is located directly in front of or directly behind the center of the bottom of the urea tank (6).

4. The vehicle urea concentration detection method according to claim 1, characterized in that: Obtaining the inclination angle θ of the urea tank (6) in the front-rear direction of the vehicle and the acceleration a of the vehicle when the vehicle is traveling, and determining the vehicle driving mode according to the inclination angle θ and the acceleration a, including: When the inclination angle θ is less than a preset inclination angle, the vehicle is in the flat ground driving mode; When the inclination angle θ is not less than the preset inclination angle and the acceleration a is within the preset acceleration range, the vehicle is in the uniform uphill and downhill mode; When the inclination angle θ is not less than the preset inclination angle and the acceleration a is not within the preset acceleration range, the vehicle is in the uphill acceleration and downhill deceleration mode or the uphill deceleration and downhill acceleration mode.

5. The vehicle urea concentration detection method according to claim 1, characterized in that: If a reed switch liquid level sensor is used to detect the liquid level of the urea solution in the urea tank (6), before determining the vehicle driving mode according to the inclination angle θ, the liquid level h and the acceleration a, the following steps are also included: It is determined whether the reed switch liquid level sensor is stuck. If the reed switch liquid level sensor is not stuck, the vehicle driving mode is determined according to the inclination angle θ, the liquid level height h and the acceleration a.

6. The vehicle urea concentration detection method according to claim 5, characterized in that: After confirming that the reed switch liquid level sensor is not stuck, record the liquid level height currently detected by the reed switch liquid level sensor; Next time when it is confirmed that the reed switch liquid level sensor is not stuck, the recorded liquid level height is updated; When the reed switch liquid level sensor is stuck, the vehicle driving mode is determined according to the inclination angle θ, the recorded liquid level height and the acceleration a.

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