A urea solution rapid thawing device for vehicle and a method for controlling urea solution injection

Abstract

This invention discloses a rapid thawing device for automotive urea solution and a method for controlling urea solution injection. The device, located in a urea tank, includes a heat insulation chamber, a heating pipe, a temperature sensor assembly, and a controller. The heating pipe is located inside the heat insulation chamber. The temperature sensor assembly measures the temperature of the urea solution inside and outside the heat insulation chamber and is electrically connected to the controller. An opening is provided on the wall of the heat insulation chamber, allowing the urea solution to enter and exit the chamber. The controller controls the start / stop of the urea pump and urea injection based on the temperature. This device divides the urea solution into a rapidly thawing portion and a slowly thawing portion. The rapidly thawing portion allows the urea pump to start working quickly, while the slowly thawing portion supports continuous operation of the urea pump. This device and method can meet the thawing time requirements of a urea injection system with relatively low heating power.

Description

Technical Field

[0001] This invention belongs to the field of exhaust gas treatment technology, and particularly relates to a rapid defrosting device for automotive urea solution and a method for controlling urea solution injection. Background Technology

[0002] The automotive urea solution is a 32.5% urea solution, used as a carrier for the reducing agent (ammonia) in SCR (Selective Catalytic Reduction). Under the action of the SCR catalyst, ammonia reacts with nitrogen oxides (NOx) in engine exhaust (NOx is a harmful gas that causes acid rain, smog, and photochemical smog; it is one of the main hazardous substances in engine emissions that need to be controlled) to produce nitrogen and water, thereby removing NOx.

[0003] Using ammonia directly in an SCR system presents safety concerns and is inconvenient in terms of storage, transportation, and use. Therefore, current SCR systems use urea solution to generate ammonia. The specific process involves injecting a urea solution into the exhaust gas system. Under the influence of heat and water in the exhaust gas, the injected urea solution undergoes pyrolysis and hydrolysis to convert into ammonia.

[0004] Urea solution has the problem of freezing at low temperatures. Therefore, in practical applications, the eutectic urea solution (mass concentration 32.5%) with the lowest freezing temperature is selected as the automotive urea solution. Since automotive urea solution will still freeze at -11 degrees Celsius, it needs to be heated by a heating device to liquefy it before use when the ambient temperature is below -11 degrees Celsius.

[0005] There are two main types of heating devices for automotive urea solution: coolant heating and electric heating. Coolant heating is generally used in larger urea tanks. When the coolant is heated, the engine coolant passes through a heating pipe, where heat is exchanged, thus heating the urea solution. Heating serves two purposes: defrosting and preventing freezing. When the engine starts running, the urea solution first needs to be defrosted, and when the ambient temperature is very low, the urea solution needs to be maintained at a certain temperature to prevent it from refreezing.

[0006] There is a time limit for thawing urea solution; that is, after the engine is ignited and started, the urea solution needs to be thawed within a certain period of time. This thawing time is stipulated by regulations. For example, the China VI emission standard requires that the urea solution be thawed within 70 minutes of engine start-up, and urea injection should begin. In the engine system, the coolant generally provides sufficient temperature and heat to thaw the urea solution in the urea tank and maintain its liquid state in cold environments. However, due to limitations imposed by cooling circuit design, engine size, weight, cost, and operating conditions, the coolant flow rate cannot be too high. This results in insufficient heating power to melt the frozen urea solution in the tank within a short time in applications with large urea tank volumes. Another factor affecting the heating power of the urea tank is the contact area between the coolant and the urea solution within the tank. To increase heating power, the contact area between the coolant and urea solution needs to be increased in the design of the coolant heating pipeline in the urea tank. According to ISO22241 standard, the coolant heating pipeline is generally made of stainless steel (such as SS303, SS304, SS316). Increasing the coolant pipeline will greatly affect the shape, installation, weight, reliability and cost of the urea tank. Summary of the Invention

[0007] Purpose of the invention: The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a rapid defrosting device for automotive urea solution and a method for controlling the injection of urea solution.

[0008] To address the aforementioned technical problems, in a first aspect, a rapid defrosting device for automotive urea solution is disclosed. Located within a urea tank, the device includes a heat insulation cavity, a heating element, a temperature sensor assembly, and a controller. The heating element is located inside the heat insulation cavity. The temperature sensor assembly measures the temperature of the urea solution inside and outside the heat insulation cavity and is electrically connected to the controller. An opening is provided on the wall of the heat insulation cavity, allowing the urea solution to enter and exit the cavity through the opening. The controller controls the start / stop of the urea pump connected to the urea tank and the urea injection based on the temperature.

[0009] Furthermore, the temperature sensor assembly includes a first temperature sensor and a second temperature sensor, the first temperature sensor being located inside the insulation cavity and the second temperature sensor being located outside the insulation cavity; the heating device is a coolant heating pipe used to heat the urea solution inside the insulation cavity.

[0010] Furthermore, a check valve is provided on the opening.

[0011] Furthermore, the heat insulation cavity includes a heat insulation shell, which is used to reduce heat conduction so that the heat released by the coolant heating pipe is first used to heat the urea solution inside the heat insulation cavity; the heat insulation shell is provided with corresponding openings.

[0012] Furthermore, the heat insulation cavity also includes a reflective liner, which is fixedly disposed on the inner wall of the heat insulation shell and has corresponding openings.

[0013] Secondly, a method for controlling urea solution injection is disclosed, using the aforementioned vehicle urea solution rapid defrosting device, comprising:

[0014] Step 1: Obtain the first temperature measurement value from the first temperature sensor. If the first temperature measurement value is greater than the first temperature threshold, turn on the urea pump connected to the urea tank and allow urea injection; otherwise, determine whether there is a heating fault.

[0015] Step 2: If there is no heating fault, obtain the second temperature measurement value of the second temperature sensor to determine whether there is a sensor fault.

[0016] Step 3: If there is no sensor fault, continue with Step 1.

[0017] Furthermore, it also includes step 4, after turning on the urea pump and allowing urea injection in step 1, acquiring the second temperature measurement value of the second temperature sensor, and if the second temperature measurement value does not exceed the second temperature threshold, determining whether there is a heating fault;

[0018] Step 5: If there is no heating fault, determine whether the total amount of urea injected is greater than the allowable amount. If the total amount of urea injected is greater than the allowable amount, stop urea injection and continue to step 4; otherwise, directly execute step 4.

[0019] Furthermore, in step 1, determining whether a heating fault exists includes: determining whether the heating time exceeds a first time threshold; if the heating time exceeds the first time threshold, then a heating fault is determined to exist.

[0020] Furthermore, in step 2, determining whether a sensor malfunction exists includes: determining whether the second temperature measurement value is greater than the second temperature threshold. If the second temperature measurement value is greater than the second temperature threshold, then a sensor malfunction is determined to exist.

[0021] Further, in step 4, determining whether a heating fault exists includes: determining whether the heating time exceeds a second time threshold, or obtaining a first temperature measurement value from a first temperature sensor, and determining whether the first temperature measurement value is greater than a third temperature threshold. If the heating time exceeds the second time threshold, or the first temperature measurement value is greater than the third temperature threshold, then a heating fault is determined, the urea pump is turned off, and urea injection is stopped.

[0022] Furthermore, the formula for calculating the allowable injection amount in step 5 is as follows:

[0023] UtH=(L-Thd_minL)*π*(D / 2)^2 (F1)

[0024] In the formula, UtH represents the allowable injection volume, L is the liquid level height of the urea solution in the heat insulation chamber measured before the urea freezes, Thd_minL is the lowest liquid level required to keep the solution in contact with the coolant heating pipeline, and D is the diameter of the heat insulation chamber.

[0025] Beneficial effects:

[0026] A rapid thawing device for vehicle urea solution provided by the present application divides the urea tank into a rapid thawing part and a slow thawing part through a heat insulation chamber. The rapid thawing part enables the urea to thaw quickly, allowing the urea pump to start working as soon as possible, rather than waiting for the urea solution in the urea tank to completely thaw before starting. At the same time, the slow thawing part can continue to thaw and supply liquid under continuous heating of the heating device to keep the urea pump running continuously. A method for controlling the injection of urea solution is provided, which, based on temperature sensors inside and outside the heat insulation chamber, can perform temperature sensor fault diagnosis, heating fault diagnosis, and control the maximum solution extraction volume to maintain the contact between the heating device in the heat insulation chamber and the urea solution, avoiding heat transfer problems caused by uneven heating and excessive extraction of the melted urea solution during the thawing process. Description of the drawings

[0027] The following further specifically describes the present invention in conjunction with the drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0028] Figure 1 It is a schematic structural diagram of a rapid thawing device for vehicle urea solution provided by an embodiment of the present application.

[0029] Figure 2 It is another schematic structural diagram of a rapid thawing device for vehicle urea solution provided by an embodiment of the present application.

[0030] Figure 3 It is a schematic flowchart of a method for controlling the injection of urea solution provided by an embodiment of the present application. Specific embodiments

[0031] The following will describe the embodiments of the present invention in conjunction with the drawings.

[0032] An object of the present invention is to provide a rapid thawing device for vehicle urea solution, which does not increase the heat input to the urea tank, does not change the coolant circuit design, but only divides the urea into two parts, one part is rapid thawing and the other part is slow thawing. The rapid thawing part enables the urea pump to work as soon as possible, and the slow thawing part supports the continuous operation of the urea pump. Another object of the present invention is to provide sensors and control methods配套 with the auxiliary thawing device to avoid heat transfer problems caused by uneven heating and excessive extraction of the melted urea solution during the thawing process.

[0033] The first embodiment of this application discloses a rapid thawing device for automotive urea solution, located in a urea tank. It includes a heat insulation chamber, a heating element (heating pipe), a temperature sensor assembly, and a controller 140. The heating pipe is located inside the heat insulation chamber. The temperature sensor assembly measures the temperature of the urea solution inside and outside the heat insulation chamber and is electrically connected to the controller 140. An opening 124 is provided on the wall of the heat insulation chamber, allowing the urea solution to enter and exit the heat insulation chamber through the opening 124. The controller 140 controls the start / stop of the urea pump and urea injection based on the temperature.

[0034] The temperature sensor assembly includes a first temperature sensor 136 and a second temperature sensor 137. The first temperature sensor 136 is located inside the heat insulation cavity, and the second temperature sensor 137 is located outside the heat insulation cavity. The heating pipeline is a coolant heating pipeline 110, which is used to heat the urea solution inside the heat insulation cavity.

[0035] like Figure 1As shown, in the specific implementation, a nozzle 100 is installed on the upper housing 125 of the urea tank. A coolant solenoid valve 105 is arranged on the nozzle 100, and a coolant inlet 101, a coolant outlet 103, a urea solution inlet 102, and a urea solution outlet 104 are opened on its side. Below the nozzle 100, a coolant heating pipe 110 is connected to the coolant inlet 101, the coolant solenoid valve 105, and the coolant outlet 103. The coolant solenoid valve 105 is connected to the controller 140 via signal line 142. The controller 140 controls the heating of the solution in the urea tank by controlling the coolant solenoid valve 105. When the engine is running, the coolant temperature can reach 60 to 90 degrees Celsius. After the coolant solenoid valve 105 is opened, the coolant flows through the coolant inlet 101, the coolant solenoid valve 105, the coolant heating pipe 110, and the coolant outlet 103. While flowing through the coolant heating pipe 110, it exchanges heat with the urea solution outside the coolant heating pipe 110, thereby heating the urea solution. Inside the urea tank, the urea solution return pipe 111 is connected to the urea solution inlet 102. The urea solution returning from the urea pump (not shown) flows into the urea tank through the urea solution inlet 102 and the urea solution return pipe 111. At the same time, there is also a urea solution suction pipe 112 in the urea tank, the upper end of which is connected to the urea solution outlet 104, and the lower end is connected to the urea filter screen 113. Driven by the urea pump, the urea solution enters the pump through the urea filter 113, the urea solution suction pipe 112, and the urea solution outlet 104. It is then atomized through a urea nozzle (not shown) and enters the SCR system (not shown). The liquid level in the urea tank is measured by the liquid level sensor 130, while the concentration of the urea solution is detected by the urea quality sensor 135. An insulating cavity exists outside the urea sensor module, which consists of the coolant heating pipe 110, the urea pipe, the liquid level sensor, and the urea quality sensor. An opening 124 is located on the wall of the insulating cavity, through which the urea solution can enter and exit. A first temperature sensor 136 is arranged inside the insulating cavity to detect the temperature of the urea solution inside, while a second temperature sensor 137 is installed outside the insulating cavity to measure the temperature of the urea solution outside the insulating cavity. To ensure contact with the urea solution when the liquid level is low, the urea quality sensor 135, the first temperature sensor 136, and the second temperature sensor 137 are all located at the bottom of the urea tank. The urea level sensor 130, the urea quality sensor 135, the first temperature sensor 136, and the second temperature sensor 137 are connected to the controller 140 via a signal harness 141.

[0036] exist Figure 1In the urea sensor module shown, the insulation chamber divides the urea solution into two parts: an inner part, which is close to the coolant heating pipe 110, thaws first when the frozen urea solution is heated, forming a localized "urea solution pool" (rapid melting zone) in the urea tank. The urea pump can draw urea solution from this pool, thus achieving urea injection as quickly as possible (the urea quality sensor operates simultaneously). At the same time, the solution in the pool exchanges heat with the surrounding "urea ice," thereby thawing the urea solution throughout the tank (forming a slow melting zone outside the insulation chamber).

[0037] The heat insulation cavity includes a heat insulation shell 122, which reduces heat conduction so that the heat released by the coolant heating pipe 110 is primarily used to heat the urea solution inside the heat insulation cavity. The heat insulation shell 122 has corresponding openings 124. Within the heat insulation cavity, the heat insulation shell 122 effectively reduces heat conduction, ensuring that the heat released by the heating pipe is primarily used to heat the urea solution inside the cavity. The heat insulation shell 122 can be made of plastic materials permitted by ISO 22241 standards, such as polyethylene, polypropylene, polyisobutylene, perfluoroalkoxy resin (PFA), polyvinylidene fluoride (PFE), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), copolymers of vinylidene fluoride and hexafluoropropylene, etc.

[0038] The heat insulation cavity also includes a reflective liner 121, which is fixedly disposed on the inner wall of the heat insulation shell 122 and has corresponding openings 124. The reflective liner 121 serves two purposes: one is to concentrate heat within the heat insulation cavity, and the other is to conduct heat rapidly, resulting in a more uniform heat distribution. Both of these functions facilitate the rapid thawing of the urea solution within the heat insulation cavity. The reflective liner 121 can be made of metallic materials permitted by the ISO 22241 standard, such as austenitic high-alloy nickel-chromium steel, nickel-chromium steel, stainless steel, titanium, Ni-Mo-Cr-Mn-Cu-Si-Fe alloys, etc.

[0039] The opening 124 on the insulation cavity serves two purposes: firstly, it acts as a heat exchange channel between the solutions inside and outside the insulation cavity, allowing the hot solution inside to contact and heat the freezing solution outside; secondly, it serves as a replenishment channel, ensuring that the solution inside the insulation cavity is replenished by the solution outside after being pumped away by the urea pump. The first function requires that the solution inside the insulation cavity maintain a certain volume. Insufficient volume will prevent the heating pipes inside the insulation cavity from effectively heating the solution outside, resulting in a lack of external solution replenishment. In severe cases, once the solution inside the insulation cavity is depleted by the urea pump, it will trigger urea quality or even urea pump malfunction alarms, causing the SCR system to shut down. The second function, when heating is uneven, can sometimes lead to prolonged thawing time. For example, when using… Figure 1When the heating pipes are installed as shown, the urea near the coolant heating pipe 110 will thaw first during heating. The thawed liquid will flow out of the insulation cavity through the opening 124. However, because the density of the liquid is greater than that of the frozen urea "ice," this liquid will remain at the bottom of the urea tank, creating a gap between the coolant heating pipe 110 and the external ice. This gap will lead to poor heat transfer and prolong the thawing time. To reduce the impact of this problem, such as... Figure 2 As shown, a check valve 201 can be added to the opening 124. Under the action of the check valve 201, the partially thawed liquid can remain in the insulation cavity, maintaining contact between the heating pipe and the frozen urea solution, thereby maintaining good thermal conductivity.

[0040] Generally, in an SCR system, the urea pump starts based on the temperature of the urea solution; the pump only starts if the urea solution temperature exceeds a certain set temperature. Figure 1 In the urea tank shown, due to uneven heating, if the urea pump starts too early and draws too much urea, the frozen urea in contact with the heating pipes will thaw and be drawn away, causing the heating pipes to separate from the frozen urea. This further leads to heating difficulties or even a continuous supply of urea solution. To solve this problem and diagnose both temperature sensor and heating faults, the measurements from the urea level sensor 130, the first temperature sensor 136, and the second temperature sensor 137 can be used to control the urea pump and injection system.

[0041] The second embodiment of this application discloses a method for controlling urea solution injection, using the above-mentioned vehicle urea solution rapid defrosting device, including:

[0042] Step 1: Obtain the first temperature measurement value of the first temperature sensor 136. If the first temperature measurement value is greater than the first temperature threshold, turn on the urea pump connected to the urea tank and allow urea injection; otherwise, determine whether there is a heating fault, including: determining whether the heating time exceeds the first time threshold. If the heating time exceeds the first time threshold, it is determined that there is a heating fault.

[0043] Step 2: If there is no heating fault, obtain the second temperature measurement value of the second temperature sensor 137 and determine whether there is a sensor fault, including: determining whether the second temperature measurement value is greater than the second temperature threshold. If the second temperature measurement value is greater than the second temperature threshold, then it is determined that there is a sensor fault.

[0044] Step 3: If there is no sensor fault, continue with Step 1.

[0045] This embodiment also includes step 4. After turning on the urea pump and allowing urea injection in step 1, the second temperature measurement value of the second temperature sensor 137 is obtained. If the second temperature measurement value does not exceed the second temperature threshold, it is determined whether there is a heating fault. This includes: determining whether the heating time exceeds the second time threshold, or obtaining the first temperature measurement value of the first temperature sensor 136 and determining whether the first temperature measurement value is greater than the third temperature threshold. If the heating time exceeds the second time threshold, or the first temperature measurement value is greater than the third temperature threshold, it is determined that there is a heating fault, the urea pump is turned off, and urea injection is stopped.

[0046] Step 5: If there is no heating fault, determine whether the total urea injection volume exceeds the allowable injection volume. If the total urea injection volume exceeds the allowable injection volume, stop urea injection and continue to step 4; otherwise, directly execute step 4. The formula for calculating the allowable injection volume is as follows:

[0047] UtH=(L-Thd_minL)*π*(D / 2)^2 (F1)

[0048] In the formula, UtH represents the allowable injection volume, L is the liquid level of the urea solution in the insulation cavity measured before the urea freezes, Thd_minL is the minimum liquid level required to keep the solution in contact with the cooling liquid heating pipe 110, which can be set as the height of the spiral part of the heating pipe, and D is the diameter of the insulation cavity.

[0049] In one embodiment, the above-mentioned integrated control is implemented by a program running in the controller 140, and the flowchart of the program is as follows: Figure 3As shown in the diagram. After the program starts, it first activates heating, then checks if the temperature measurement value T136 obtained from the first temperature sensor 136 is greater than the first temperature threshold Thd_136H. If T136 is not greater than the first temperature threshold Thd_136H, it checks if the heating time exceeds the first time threshold. If the heating time exceeds the first time threshold, a heating fault is triggered, and the program stops. Otherwise, it checks if the temperature measurement value T137 obtained from the second temperature sensor 137 is greater than the second temperature threshold Thd_137H. If T137 is greater than the second temperature threshold Thd_137H, a sensor fault is triggered, and the program stops. Otherwise, the program returns to comparing the T136 value with the first temperature threshold Thd_136H. If T136 is greater than the first temperature threshold Thd_136H, the urea pump is activated and urea injection is allowed, and then it checks if T137 is greater than the second temperature threshold Thd_137H. If T137 is greater than the second temperature threshold Thd_137H, then urea injection is allowed again, and then the process stops. Otherwise, it checks whether the heating time exceeds the second time threshold or whether T136 is greater than the third temperature threshold Thd_136F. If so, a heating fault is set, and the program stops after shutting down the urea pump and stopping urea injection. Otherwise, it checks whether the total urea injection amount Ut is greater than the allowed injection amount UtH. If Ut is greater than UtH, it indicates that too much urea has been injected. In this case, the program stops urea injection and then returns to the comparison between T137 and the second temperature threshold Thd_137H. Otherwise, it directly returns to the comparison between T137 and the second temperature threshold Thd_137H.

[0050] like Figure 3 In the control program shown, the first temperature threshold Thd_136H and the second temperature threshold Thd_137H must be higher than the freezing temperature of the urea solution (for example, the freezing temperature of a 32.5 wt% urea solution is -11 degrees Celsius), while the third temperature Thd_136F can be set to the temperature at which the urea solution is prone to deterioration, such as 35 degrees Celsius. The allowable injection quantity UtH can be calculated by the following formula:

[0051] UtH=(L-Thd_minL)*π*(D / 2)^2 (F1)

[0052] In the formula, L is the liquid level height measured before the urea freezes, Thd_minL is the minimum liquid level required to keep the solution in contact with the heating pipe, which can be set as the minimum height of the spiral part of the heating pipe, and D is the diameter of the insulation cavity.

[0053] The first and second time thresholds can be set to a value higher than the maximum time that T136 and T137 reach the first and second temperature thresholds when heated at the lowest system operating temperature (e.g., -35 degrees Celsius).

[0054] In its specific implementation, this application provides a computer storage medium and a corresponding data processing unit. The computer storage medium is capable of storing a computer program, which, when executed by the data processing unit, can run the invention's content regarding a method for controlling urea solution injection, as well as some or all of the steps in various embodiments. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0055] Those skilled in the art will clearly understand that the technical solutions in the embodiments of the present invention can be implemented using computer programs and their corresponding general-purpose hardware platforms. Based on this understanding, the technical solutions in the embodiments of the present invention, or the parts that contribute to the prior art, can be embodied in the form of computer programs, i.e., software products. These computer program software products can be stored in a storage medium and include several instructions to cause a device containing a data processing unit (which may be a personal computer, server, microcontroller, MUU, or network device, etc.) to execute the methods described in various embodiments or certain parts of the embodiments of the present invention.

[0056] This invention provides a rapid thawing device for automotive urea solution and a method for controlling urea solution injection. Many methods and approaches exist for implementing this technical solution; the above description is merely a specific embodiment of this invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technology.

Claims

1. A rapid defrosting device for automotive urea solution, characterized in that, Located in a urea tank, it includes an insulation cavity, a heating device, a temperature sensor assembly, and a controller. The heating device is located inside the insulation cavity. The temperature sensor assembly is used to measure the temperature of the urea solution inside and outside the insulation cavity and is electrically connected to the controller. The insulation cavity wall is provided with an opening, through which the urea solution can enter and exit the insulation cavity. The controller is used to control the start and stop of the urea pump connected to the urea tank and the urea injection according to the temperature. The temperature sensor assembly includes a first temperature sensor and a second temperature sensor, with the first temperature sensor located inside the insulation cavity and the second temperature sensor located outside the insulation cavity; the heating device is a coolant heating pipe used to heat the urea solution inside the insulation cavity. The controller is used to control the start / stop of the urea pump connected to the urea tank and the urea injection according to the temperature, including: Obtain the first temperature measurement value from the first temperature sensor. If the first temperature measurement value is greater than the first temperature threshold, turn on the urea pump connected to the urea tank and allow urea injection. After the urea pump is turned on and urea injection is allowed, the second temperature measurement value of the second temperature sensor is obtained. If the second temperature measurement value does not exceed the second temperature threshold, it is determined whether the total amount of urea injection is greater than the allowable injection amount. If the total amount of urea injection is greater than the allowable injection amount, urea injection is stopped.

2. The rapid defrosting device for automotive urea solution according to claim 1, characterized in that, A check valve is installed on the opening.

3. The rapid defrosting device for automotive urea solution according to claim 2, characterized in that, The heat insulation cavity includes a heat insulation shell, which is used to reduce heat conduction so that the heat released by the coolant heating pipe is first used to heat the urea solution inside the heat insulation cavity; the heat insulation shell is provided with corresponding openings.

4. The rapid defrosting device for automotive urea solution according to claim 3, characterized in that, The heat insulation cavity also includes a reflective liner, which is fixedly disposed on the inner wall of the heat insulation shell and has corresponding openings.

5. A method for controlling urea solution injection, using the vehicle urea solution rapid defrosting device according to any one of claims 1-4, characterized in that, include: Step 1: Obtain the first temperature measurement value from the first temperature sensor. If the first temperature measurement value is greater than the first temperature threshold, turn on the urea pump connected to the urea tank and allow urea injection. Otherwise, determine if there is a heating malfunction; Step 2: If there is no heating fault, obtain the second temperature measurement value of the second temperature sensor to determine whether there is a sensor fault. Step 3: If there is no sensor fault, continue with Step 1.

6. The method for controlling urea solution injection according to claim 5, characterized in that, The process also includes step 4, where after the urea pump is turned on and urea injection is allowed in step 1, the second temperature measurement value of the second temperature sensor is obtained. If the second temperature measurement value does not exceed the second temperature threshold, it is determined whether there is a heating fault. Step 5: If there is no heating fault, determine whether the total amount of urea injected is greater than the allowable amount. If the total amount of urea injected is greater than the allowable amount, stop urea injection and continue to step 4; otherwise, directly execute step 4.

7. The method for controlling urea solution injection according to claim 6, characterized in that, Step 1 determines whether a heating fault exists, including: determining whether the heating time exceeds a first time threshold. If the heating time exceeds the first time threshold, a heating fault is determined to exist.

8. The method for controlling urea solution injection according to claim 7, characterized in that, Step 2, determining whether a sensor malfunction exists, includes: determining whether the second temperature measurement value is greater than the second temperature threshold. If the second temperature measurement value is greater than the second temperature threshold, then a sensor malfunction is determined to exist.

9. A method for controlling urea solution injection according to claim 8, characterized in that, Step 4 determines whether a heating fault exists, including: determining whether the heating time exceeds the second time threshold, or obtaining the first temperature measurement value of the first temperature sensor and determining whether the first temperature measurement value is greater than the third temperature threshold. If the heating time exceeds the second time threshold or the first temperature measurement value is greater than the third temperature threshold, then a heating fault is determined, the urea pump is turned off, and urea injection is stopped.

10. A method for controlling urea solution injection according to claim 9, characterized in that, The formula for calculating the allowable injection volume in step 5 is as follows: UtH = (L-Thd_minL) * π * (D / 2)^2 (F1) In the formula, UtH represents the allowable injection volume, L is the liquid level height of the urea solution in the insulation cavity measured before the urea freezes, Thd_minL is the minimum liquid level required to keep the solution in contact with the cooling liquid heating pipe, and D is the diameter of the insulation cavity.

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