Anti-freezing device of internal combustion engine tail gas after-treatment reactant heat exchanger
By setting up a liquid pump and a gas check valve in the coil, the liquid is discharged and air is introduced, the freezing and cracking problem caused by the urea solution in cold weather is solved, ensuring the reliability of the system.
Patent Information
- Application Number
- CN202421953157.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-13
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2034-08-13
AI Technical Summary
In the existing internal combustion engine exhaust after-treatment system, the urea solution freezes and cracks in cold weather.
By setting a liquid pump and a gas check valve in the coil, the liquid in the coil is discharged and air is introduced to balance the pressure inside and outside the coil to avoid freezing and cracking caused by the icy expansion of the liquid.
It effectively avoids frozen cracks and damage of coils and adjacent parts, and achieves reliability protection in cold weather.
Smart Images
Figure CN223179345U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of internal combustion engine exhaust gas aftertreatment, and particularly relates to an antifreeze heat exchanger. More specifically, the utility model relates to an antifreeze device for a heat exchanger of an internal combustion engine exhaust gas aftertreatment reactant. Background Art
[0002] In current internal combustion engine exhaust gas purification systems, especially lean-burn internal combustion engines, such as diesel engine exhaust gas purification, a reactant, such as an aqueous urea solution reactant (hereinafter referred to as "urea"), needs to be added to the exhaust system, i.e., the post-treatment device, to reduce nitrogen oxides (NOx). The national standard reactant is a 32.5% aqueous urea solution. In engineering applications, the reactant is carried on a vehicle in a urea tank. Under the control of a DCU (post-treatment controller) by a urea pump, it is extracted and sprayed into the post-treatment device, such as an SCR system, according to the vehicle engine working conditions. However, the above national standard reactant will freeze in cold weather, such as below -11°C. Therefore, a heating system is required to heat and thaw the reactant. The most common method is to use engine coolant, hereinafter referred to as "circulating water", as a heating medium. By arranging a heat exchanger, hereinafter referred to as a "coil", in the urea tank, the circulating water is introduced into the coil for circulation; in this way, the heat brought by the circulating water from the engine is conducted to the urea to heat and thaw it.
[0003] Figure 1 is a most common urea heating schematic diagram. The heating function of this system is mainly completed by a heat exchanger, commonly known as coil 100; the above coil is placed in urea tank 200. There is urea 220 in the urea tank; urea tank 100 is connected to urea tank cover 400 through a buckle 300; inside (on) the urea tank cover, a circulating water inlet pipe joint 500 and a circulating water outlet pipe joint 600 are arranged, which are respectively communicated with the inlet pipe 110 and outlet pipe 120 of the coil 100 through a flow channel (not shown) inside the urea tank cover; the inlet pipe joint 500 and the outlet pipe joint 600 are respectively connected to the circulating water supply pipe 510 and the return pipe 610 at the engine end ( Figure 2 ); a normally closed switch valve 550 is arranged on the circulating water supply pipeline 510 or in the flow channel inside (on) the urea tank cover 400 ( Figure 2 ). In this way, when it is necessary to heat the urea, the post-treatment system controller DCU (not shown) opens the above switch valve 550, so that the circulating water can continuously flow into the coil 100 to achieve heat exchange, conduct the heat of the circulating water to the urea, and heat and thaw it.
[0004] Under normal circumstances, the engine circulating water is antifreeze liquid and will not freeze in cold weather. However, in the market, many users do not use antifreeze but directly use natural water, such as tap water. Water can freeze below 0°C. When the circulating water freezes, its volume expands, causing the coil pipes, especially the joints between the coil pipes and the urea tank cover or the internal flow channels of the urea tank cover, to burst, commonly known as freezing and cracking.
[0005] The main problem to be solved by the present utility model is to prevent the above-mentioned freezing and cracking phenomenon. For this purpose, the following invention content is disclosed. Utility Model Content
[0006] An object of the present utility model is to provide an antifreeze device for an internal combustion engine exhaust gas aftertreatment reactant heat exchanger, which discharges the liquid in the coil pipes, returns it to the engine water tank, and introduces air at the same time; in this way, in cold weather, when the residual liquid in the coil pipes freezes and expands in volume, the air in the coil pipes is compressed to absorb the pressure, avoiding freezing and damage of the coil pipes and other components adjacent thereto.
[0007] To solve the above technical problems, the present utility model provides an antifreeze device for an internal combustion engine exhaust gas aftertreatment reactant heat exchanger, including a power mechanism. The power mechanism includes a liquid pump and a gas check valve. A liquid pump is provided on the liquid discharge pipeline communicated with the liquid discharge pipe of the coil pipes, and at the same time, a gas check valve is provided on the liquid inlet pipeline between the liquid inlet pipe of the coil pipes and the switching valve; the liquid pump is used to pump out the liquid in the coil pipes, and at the same time, under the action of negative pressure in the coil pipes, the gas check valve opens to introduce air into the coil pipes.
[0008] Preferably, a liquid check valve is provided on the liquid discharge pipe of the coil pipes or on the liquid discharge pipeline communicated with the liquid discharge pipe of the coil pipes, and it is set to only allow the liquid in the coil pipes to flow out.
[0009] Preferably, one end of the switching valve is connected to the engine water tank through a liquid inlet pipeline, and the other end is connected to the liquid inlet pipe of the coil pipes. The switching valve is controlled to open and close by the engine ECU or the DCU of the aftertreatment system.
[0010] Preferably, after the liquid in the coil pipes is pumped out from the liquid discharge pipe of the coil pipes, it directly flows to the outside environment or returns to the engine water tank.
[0011] Preferably, both the liquid check valve and the gas check valve are mechanical valves, and they are switched on and off under the drive of the hydraulic and pneumatic pressure differences inside and outside the coil pipes.
[0012] The present utility model has at least the following beneficial effects:
[0013] 1. The utility model discharges the liquid in the coil pipe and returns it to the engine water tank, while introducing air at the same time. In this way, in cold weather, when the residual liquid in the coil pipe freezes and expands in volume, the air in the coil pipe is compressed to absorb the pressure, avoiding the coil pipe and other adjacent components from being frozen and cracked.
[0014] 2. The utility model can achieve a very reliable effect of avoiding the coil pipe and other adjacent components from being frozen and cracked when the residual liquid in the coil pipe freezes and expands in volume through simple structural transformation.
[0015] Other advantages, objectives and features of the utility model will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the utility model. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a schematic diagram of a heating system for an SCR urea aqueous solution reactant of the utility model;
[0017] Figure 2 is Figure 1 a partial schematic diagram, showing the on-off valve 550 and the gas check valve 850 on the coil pipe liquid inlet pipeline 510, and a liquid pump 900 is arranged on the liquid outlet pipeline;
[0018] Figure 3 shows the same content as Figure 2 the only difference is that a liquid check valve 650 is also arranged on the liquid outlet pipeline. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0019] In order to better understand the purpose, structure and function of the utility model, the following further detailed description of the utility model is made with reference to the drawings, so that those skilled in the art can implement it according to the description in the specification.
[0020] It should be noted that in the description of the utility model, the orientation or positional relationship indicated by the terms "horizontal", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. In actual devices, these orientations may vary due to the placement method of the device, so it cannot be understood as a limitation to the utility model. In addition, although urea or urea solution is used as an example to illustrate the function of the metering system in this article, the utility model is applicable to any other fluid.
[0021] After the engine stops, a part of the liquid in the coil pipe is discharged, so that when the residual liquid in the coil pipe freezes and expands in cold weather, the air in the coil pipe is compressed, reducing the pressure inside the coil pipe and preventing the coil pipe and other components adjacent to it from being frozen and damaged. While discharging a part of the liquid in the coil pipe, air is introduced to balance the pressure inside and outside the coil pipe, which is specifically realized by a power mechanism, avoiding and reducing the leakage of liquid from the liquid inlet pipe and the liquid outlet pipe communicating with the coil pipe into the coil pipe.
[0022] In one implementation, as Figures 1 to 3 shown, while sucking out the liquid in the coil pipe by suction outside the liquid outlet end of the coil pipe, air is introduced through the liquid inlet end of the coil pipe. Specifically, by setting a liquid pump and a gas check valve, the pressure inside and outside the coil pipe is balanced, avoiding and reducing the leakage of liquid from the liquid inlet and outlet pipes into the coil pipe. When the aftertreatment system stops working, the above-mentioned switch valve closes, and the aftertreatment system controller (DCU) starts the water pump to pump out the liquid in the coil pipe and return it to the engine water tank through the liquid outlet pipe. In this way, in cold winter, when the liquid in the coil pipe freezes and expands, the air in the coil pipe can be compressed to absorb the pressure, preventing the coil pipe and other components adjacent to it from bursting (freezing).
[0023] Embodiment 1
[0024] As Figure 1 shown, the SCR urea aqueous solution reactant (hereinafter referred to as "urea") heating system heats the urea 220 in the urea tank 200 through a heat exchanger, that is, the coil pipe 100. Its structure is as follows: The coil pipe 100 is placed in the urea tank 200, and there is urea 220 in the urea tank; The coil pipe 100 is connected to the bayonet 300 and the urea tank cover 400 to form an assembly, and is connected to the urea tank 200 through the bayonet 300; The urea tank cover 400 is provided with a circulating water inlet pipe joint 500 and an outlet pipe joint 600, which are respectively communicated with the inlet pipe 110 and the outlet pipe 120 of the coil pipe 100 through the flow channels (not shown) inside the urea tank cover 400; The inlet pipe joint 500 and the outlet pipe joint 600 are respectively communicated with the circulating water supply pipe 510 and the return pipe 610 ( Figure 2 ); A normally closed switch valve 550 (closed when powered off) is arranged on the above-mentioned supply pipe 510;
[0025] A liquid pump (water pump) is arranged on the outlet pipe 610, and a gas check valve 850 is arranged on the inlet pipe between the inlet pipe 110 and the switch valve 550.
[0026] When the after-treatment system is working properly, the urea coil 100 has two working states: 1) No need to heat the urea 220: At this time, the switching valve 550 on the liquid supply pipeline 510 is in the closed state, and the liquid in the coil will not flow; 2) Need to heat the urea 220, such as heating and thawing the urea in cold weather: At this time, the DCU opens the switching valve 550 on the liquid supply pipeline 510, the circulating water flows in from the coil liquid inlet pipe 110 and flows out from the liquid outlet pipe 120, the liquid in the coil keeps flowing, and transfers the heat brought by the circulating water to the urea.
[0027] When the engine shuts down and the after-treatment system stops working, the after-treatment system has at least 60 seconds to complete various system shutdown operations before power-off; at this time, the DCU closes the switching valve 550, starts the water pump 900 to pump the liquid from the coil, and returns it to the engine water tank through the liquid outlet pipeline 610; at this time, a negative pressure will be generated in the coil, and the above-mentioned gas check valve 850 opens under the negative pressure to allow air to enter the coil. When the liquid in the coil is discharged from the coil, it directly flows to the outside environment, preferably, it returns to the engine water tank.
[0028] When winter comes and the residual circulating water in the coil freezes and expands in volume, the air inside the coil can be compressed, absorb the pressure, and greatly reduce the pressure inside the coil, thus avoiding the coil and other adjacent components from being frozen and cracked.
[0029] In this embodiment, it is assumed that the circulating water returned to the engine water tank will not flow back into the coil; otherwise, the following embodiment needs to be adopted.
[0030] Embodiment 2
[0031] As Figure 3 shown, in order to prevent the discharged liquid from flowing back into the coil, similar to Embodiment 1, the only difference is that a liquid check valve 650 is arranged at any position on the liquid outlet pipeline 610, for example, arranged between the coil liquid outlet pipe and the engine water tank, only allowing the liquid in the coil to flow to the engine water tank, and not allowing the liquid to flow back from the engine water tank into the coil.
[0032] The liquid check valve and the gas check valve in all the above embodiments are preferably a simple mechanical valve, which are switched on and off under the hydraulic pressure and air pressure inside and outside the coil respectively.
[0033] The switching valve in all of the above embodiments is connected to the engine water tank at one end through a liquid inlet (liquid supply) pipeline, and to the liquid inlet pipe of the coil at the other end. Preferably, it is a normally closed electrically controlled switching valve, which is controlled by the engine ECU or the DCU of the aftertreatment system; it is opened when urea heating is required, so that the engine cooling circulating water flows from the engine water tank into the coil through the liquid inlet pipeline, and then flows back to the engine water tank through the liquid outlet pipeline; when urea heating is not required, including when the engine is shut down, the aftertreatment system stops working or the aftertreatment system is powered off, it automatically closes.
[0034] It can be understood that the present utility model is described through some embodiments. As is known to those skilled in the art, without departing from the spirit and scope of the present utility model, various changes or equivalent replacements can be made to these features and embodiments. Although the embodiments of the present utility model have been disclosed above, it is not limited to only the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present utility model. For those familiar with the field, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present utility model is not limited to specific details and the illustrated and described examples here.
Claims
1. An anti-freezing device for a heat exchanger of an internal combustion engine exhaust after-treatment reactant, characterized in that, It includes a power mechanism, and the power mechanism includes a liquid pump and a gas check valve. A liquid pump is provided on the liquid outlet pipeline communicated with the liquid outlet pipe of the coil pipe. Meanwhile, a gas check valve is provided on the liquid inlet pipeline between the liquid inlet pipe of the coil pipe and the switching valve. The liquid pump is used to pump out the liquid in the coil pipe. Meanwhile, under the action of negative pressure in the coil pipe, the gas check valve opens to introduce air into the coil pipe.
2. The anti-freezing device of the internal combustion engine exhaust gas aftertreatment reactant heat exchanger according to claim 1, characterized in that, A liquid check valve is provided on the liquid outlet pipe of the coil pipe or on the liquid outlet pipeline communicated with the liquid outlet pipe of the coil pipe, and it is set to only allow the liquid in the coil pipe to flow out.
3. The anti-freezing device of the internal combustion engine exhaust aftertreatment reactant heat exchanger according to claim 1, characterized in that, One end of the switching valve is connected to the engine water tank through the liquid inlet pipeline, and the other end is connected to the liquid inlet pipe of the coil pipe. The switching valve is controlled to open and close by the engine ECU or the DCU of the aftertreatment system.
4. The anti-freezing device of the internal combustion engine exhaust gas post-treatment reactant heat exchanger according to claim 1, characterized in that, After the liquid in the coil pipe is pumped out from the liquid outlet pipe of the coil pipe, it directly flows to the outside environment or returns to the engine water tank.
5. The anti-freezing device of the internal combustion engine exhaust aftertreatment reactant heat exchanger according to claim 2, characterized in that, Both the liquid check valve and the gas check valve are mechanical valves, and they are switched on and off under the drive of the hydraulic pressure and air pressure difference inside and outside the coil pipe.