Anti-freezing device of internal combustion engine tail gas after-treatment reactant heat exchanger
By introducing an air pressure delivery device into the coil, the liquid is discharged and returned to the engine water tank, the coil freezing and cracking caused by the urea aqueous solution in cold weather is solved, and the anti-freezing effect is achieved.
Patent Information
- Application Number
- CN202421952988.7
- 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 exhaust purification system of existing internal combustion engines, the urea aqueous solution freezes in cold weather and causes the coil to freeze and crack.
The air pressure delivery device is introduced into the coil, and compressed air is transported into the coil through the air pump, the liquid in the coil is discharged and returned to the engine water tank or the external environment, balance the internal and external pressure of the coil and avoid freezing and cracking.
It effectively avoids freeze cracking and damage of coils and adjacent parts, and achieves a reliable anti-freeze effect through simple structural transformation.
Smart Images
Figure CN223179344U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of after-treatment of exhaust gas from an internal combustion engine, and more particularly to an antifreeze heat exchanger. More particularly, the utility model relates to an antifreeze device for a heat exchanger for a reactant in after-treatment of exhaust gas from an internal combustion engine. Background Art
[0002] Current internal combustion engine exhaust purification systems, particularly those for lean-burn internal combustion engines such as diesel engines, require the addition of a reactant, such as a urea-water solution (hereinafter referred to as "urea"), to the exhaust system, or aftertreatment system, to reduce nitrogen oxides (NOx). The national standard reactant is a 32.5% urea-water solution. In engineering applications, this reactant is carried onboard a urea tank. A urea pump, controlled by the DCU (aftertreatment control unit), pumps and injects it into an aftertreatment system, such as an SCR system, based on the vehicle's engine operating conditions. However, this national standard reactant freezes in cold weather, such as below -11°C. Therefore, a heating system is required to thaw the reactant. The most common method uses engine coolant (hereinafter referred to as "circulating water") as the heating medium. This is achieved by placing a heat exchanger (hereinafter referred to as "coil") within the urea tank, which circulates the circulating water. This transfers heat from the engine to the urea, heating it and freezing it.
[0003] Figure 1 This is a most common urea heating diagram. The heating function of this system is mainly completed by the heat exchanger, commonly known as the coil 100; the above-mentioned coil is placed in the urea tank 200. There is urea 220 in the urea tank; the urea tank 100 is connected to the urea tank cover 400 through a snap 300; a circulating water inlet pipe joint 500 and a circulating water outlet pipe joint 600 are arranged inside (on) the urea tank cover, which are respectively connected to the inlet pipe 110 and the outlet pipe 120 of the coil 100 through the flow channel inside the urea tank cover (not shown in the figure); 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 ( Figure 2 Thus, when urea needs to be heated, the post-treatment system controller DCU (not shown) opens the switch valve 550 so that the circulating water can continuously flow into the coil 100, achieving heat exchange and transferring the heat of the circulating water to the urea, thereby heating and thawing it.
[0004] Under normal circumstances, the engine circulating water is anti-freeze liquid and will not freeze in cold weather. However, in the market, there are many users who do not use anti-freeze liquid but directly use natural water, such as tap water. Water can freeze when the temperature is 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, which is 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 utility model is disclosed. Summary of the Utility Model
[0006] An object of the present utility model is to provide an anti-freezing device for a heat exchanger of an internal combustion engine exhaust gas after-treatment reactant, 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 volume of the residual liquid in the coil pipes expands due to freezing, the air in the coil pipes is compressed to absorb the pressure, avoiding freezing and damage of the coil pipes and other components adjacent to them.
[0007] To solve the above technical problems, the present utility model provides an anti-freezing device for a heat exchanger of an internal combustion engine exhaust gas after-treatment reactant, including an air pressurization and conveying device, which is arranged outside the liquid inlet end of the coil pipes at the top of the coil pipes. The air pressurization and conveying device is used to convey compressed air into the coil pipes to extrude the liquid in the coil pipes from the liquid outlet pipe of the coil pipes, and the input of the compressed air balances the pressure inside and outside the coil pipes.
[0008] Preferably, the air pressurization and conveying device is an air pump, which is arranged between the liquid inlet pipe of the coil pipes and a switching valve.
[0009] Preferably, after the liquid in the coil pipes is extruded from the liquid outlet pipe of the coil pipes, it directly flows to the outside environment or returns to the engine water tank.
[0010] Preferably, a liquid check valve is arranged on the liquid outlet pipe of the coil pipes or on the liquid outlet pipeline communicated with the liquid outlet pipe of the coil pipes, and it is set to only allow the liquid in the coil pipes to flow out.
[0011] Preferably, the air pressurization and conveying device also has the function of a check valve, and the air pressurization and conveying device is a plunger pump or a gear pump.
[0012] Preferably, the air pressurization and conveying device only has the function of conveying compressed air, and a gas check valve is arranged between the air pressurization and conveying device and the liquid inlet pipe, and it is set to only allow outside air to flow into the coil pipes and not allow the liquid in the coil pipes to leak outwards.
[0013] 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 after-treatment system.
[0014] Preferably, the liquid one-way valve is a mechanical valve, which is switched on and off under the hydraulic drive inside and outside the coil pipe.
[0015] Preferably, both the liquid one-way valve and the gas one-way valve are mechanical valves, which are switched on and off under the drive of the hydraulic pressure and air pressure difference inside and outside the coil pipe.
[0016] The utility model has at least the following beneficial effects:
[0017] 1. By discharging the liquid inside the coil pipe and returning it to the engine water tank, and introducing air at the same time, when the residual liquid inside the coil pipe freezes and expands in volume in cold weather, the air inside the coil pipe is compressed to absorb the pressure, thus avoiding the coil pipe and other adjacent components from being frozen and damaged.
[0018] 2. Through simple structural transformation, the utility model can very reliably avoid the coil pipe and other adjacent components from being frozen and damaged when the residual liquid inside the coil pipe freezes and expands in volume.
[0019] Other advantages, objectives and features of the utility model will be partially reflected by the following description, and partially will also be understood by those skilled in the art through the research and practice of the utility model. Description of the Drawings
[0020] Figure 1 It is a schematic diagram of a heating system for an SCR urea aqueous solution reaction agent of the utility model;
[0021] Figure 2 is Figure 1 a partial schematic diagram, showing the on-off valve 550 on the liquid inlet pipeline 510 of the coil pipe and the air pump 800;
[0022] Figure 3 Showing the same content as Figure 2 except that a liquid one-way valve 650 is arranged on the liquid outlet pipeline;
[0023] Figure 4 Showing the same content as Figure 3 except that a gas one-way valve 850 is arranged downstream of the air pump. Detailed Description of the Preferred Embodiment
[0024] In order to better understand the purpose, structure and function of the utility model, the following further detailed description is made in conjunction with the drawings of the utility model, so that those skilled in the art can implement it according to the description in the specification.
[0025] It should be noted that in the description of the present utility model, the orientation or positional relationship indicated by terms such as "lateral", "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 present 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 present utility model. Additionally, although urea or urea solution is used as an example in this article to illustrate the function of the metering system, the present utility model is applicable to any other fluid.
[0026] After the engine of the present utility model stops, a part of the liquid in the coil is discharged, so that when the residual liquid in the coil freezes and expands in cold weather, the air in the coil is compressed, reducing the pressure inside the coil and preventing the coil and other adjacent components from being frozen and cracked. While discharging a part of the liquid in the coil, air is introduced to balance the pressure inside and outside the coil, preventing and reducing the leakage of liquid from the liquid inlet pipe and the liquid outlet pipe communicating with the coil into the coil.
[0027] In one embodiment, as Figures 1 to 4 shown, at the liquid inlet end of the coil, compressed air is introduced into the coil to discharge the liquid in the coil. Specifically, when the after-treatment system stops working, the DCU of the after-treatment system starts the above air pump, injects air into the above coil, and discharges the liquid in the coil, preferably back to the engine water tank. In this way, in cold winter, when the liquid in the coil freezes and expands, the air in the coil can be compressed to absorb the pressure, preventing the coil and other adjacent components from being cracked (frozen).
[0028] Embodiment 1
[0029] 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 100. Its structure is as follows: The coil 100 is placed in the urea tank 200, and there is urea 220 in the urea tank; the coil 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 100 through the flow path (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 liquid supply pipeline 510;
[0030] At the top of the coil, preferably, between the liquid inlet pipe 110 and the switch valve 550, as Figure 2 shown, an air pressurized conveying device, namely an air pump 800, is arranged at any position on the liquid inlet pipeline connecting the above-mentioned coil and the engine water tank, preferably, downstream of the switch valve at the liquid inlet end of the coil.
[0031] When the after-treatment system is working normally, the urea coil 100 has two working states: 1) It is not necessary to heat the urea 220: At this time, the switch valve 550 on the liquid supply pipeline 510 is in the closed state, and the liquid in the coil does not flow; 2) It is necessary to heat the urea 220, such as heating and thawing the urea in cold weather: At this time, the DCU opens the switch valve 550 on the liquid supply pipeline 510, the circulating water flows in from the liquid inlet pipe 110 of the coil and flows out from the liquid outlet pipe 120, and the liquid in the coil keeps flowing, transferring the heat brought by the circulating water to the urea.
[0032] 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 switch valve 550 and starts the air pump 800 to inject compressed air into the coil 100; in this way, the liquid in the coil is squeezed out of the liquid outlet pipe 120 under the pressure of the above-mentioned compressed air and flows back to the engine water tank through the liquid outlet pipeline 610. When the liquid in the coil is discharged from the coil, it directly flows to the outside environment, preferably, flows back to the engine water tank.
[0033] When winter comes and the residual circulating water in the coil freezes and expands in volume, the air inside the coil can be compressed to absorb the pressure, greatly reducing the pressure inside the coil, thereby avoiding the coil and other adjacent components from being frozen and cracked.
[0034] In this embodiment, it is assumed that the circulating water flowing back to the engine water tank will not flow back to the coil; at the same time, it is also assumed that the air pump 800 not only has the functions of compressing air and conveying air, but also has the function of a one-way valve, such as a plunger pump, a gear pump, etc., only allowing the air outside the coil to be pumped into the coil, and not allowing the liquid in the coil to leak out to the outside of the coil. Otherwise, the following embodiment needs to be adopted.
[0035] Embodiment 2
[0036] As Figure 3 shown, similar to Embodiment 1, the only difference is that a liquid one-way valve 650 is added on the liquid outlet pipeline 610 or the liquid outlet pipe 120, which only allows the circulating water to flow out, that is, flow to the engine water tank (not shown), and does not allow the circulating water to flow back into the coil.
[0037] In this embodiment, it is assumed that the air pump 800 not only has the functions of compressing air and conveying air, but also has the function of a check valve, such as a plunger pump, a gear pump, etc., which only allows air to be pumped into the coil and does not allow the liquid in the coil to leak out. Otherwise, the following embodiment needs to be adopted.
[0038] Embodiment 3
[0039] As Figure 4 shown, similar to Embodiment 2, the only difference is that a gas check valve 850 is added between the air pump 800 and the liquid inlet pipe 110, which only allows external air to flow into the coil and does not allow the liquid in the coil to leak outwards.
[0040] Preferably, the liquid check valve and the gas check valve in all the above embodiments are both a kind of simple mechanical valves, which are switched on and off under the drive of the internal and external hydraulic pressure and air pressure of the coil respectively.
[0041] One end of the switching valve in all the above embodiments is connected to the engine water tank through a liquid inlet (liquid supply) pipeline, and the other end is connected to the liquid inlet pipe of the coil. Preferably, it is a normally closed electronically 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 returns 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.
[0042] It can be understood that the present utility model is described through some embodiments. Those skilled in the art know that without departing from the spirit and scope of the present utility model, various changes or equivalent substitutions can be made to these features and embodiments. Although the embodiments of the present utility model are disclosed as 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 made. 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 illustrations shown and described herein.
Claims
1. An anti-freezing device for an exhaust after-treatment reactant heat exchanger of an internal combustion engine, characterized in that It includes an air pressurized conveying device which is arranged at the top of the coil outside the liquid inlet end of the coil. The air pressurized conveying device is used to convey compressed air into the coil so as to extrude the liquid in the coil from the liquid outlet pipe of the coil, and the input of the compressed air balances the pressure inside and outside the coil.
2. The anti-freezing device of the internal combustion engine exhaust after-treatment reactant heat exchanger according to claim 1, characterized in that, The air pressurized conveying device is an air pump which is arranged between the liquid inlet pipe of the coil and the switch valve.
3. The anti-freezing device of the internal combustion engine exhaust after-treatment reactant heat exchanger according to claim 1, characterized in that, After the liquid in the coil is extruded from the liquid outlet pipe of the coil, it directly flows to the outside environment or returns to the engine water tank.
4. The anti-freezing device for the exhaust gas after-treatment reactant heat exchanger of an internal combustion engine according to claim 1, characterized in that A liquid one-way valve is arranged on the liquid outlet pipe of the coil or on the liquid outlet pipeline communicated with the liquid outlet pipe of the coil, and it is set to only allow the liquid in the coil to flow out.
5. The anti-freezing device of the internal combustion engine exhaust after-treatment reactant heat exchanger according to claim 1 or 4, characterized in that The air pressurized conveying device also has the function of a one-way valve, and the air pressurized conveying device is a plunger pump or a gear pump.
6. The anti-freezing device of the internal combustion engine exhaust aftertreatment reactant heat exchanger according to claim 4, characterized in that, The air pressurized conveying device only has the function of conveying compressed air, and a gas one-way valve is arranged between the air pressurized conveying device and the liquid inlet pipe, and it is set to only allow the outside air to flow into the coil and not allow the liquid in the coil to leak outwards.
7. The anti-freezing device of the internal combustion engine exhaust after-treatment reactant heat exchanger according to claim 2, characterized in that, One end of the switch 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. The switch valve is controlled to open and close by the engine ECU or the DCU of the aftertreatment system.
8. The anti-freezing device of the internal combustion engine exhaust aftertreatment reactant heat exchanger according to claim 4, characterized in that, The liquid one-way valve is a mechanical valve, and it is switched on and off under the hydraulic drive inside and outside the coil.
9. The anti-freezing device for the exhaust gas post-treatment reactant heat exchanger of an internal combustion engine according to claim 6, characterized in that, Both the liquid one-way valve and the gas one-way valve are mechanical valves, and they are switched on and off under the hydraulic and pneumatic pressure differences inside and outside the coil.