A cooling system, engine and method for controlling EGR exhaust gas humidity

Abstract

The application discloses a cooling system capable of controlling EGR exhaust gas humidity, an engine and a method, solves the problem that an EGR cooler and an engine share a water tank in the prior art, and has the beneficial effects, and the specific scheme is as follows: a cooling system capable of controlling EGR exhaust gas humidity comprises a first water tank located in an engine compartment, the first water tank is independent of a second water tank for engine cooling, a first fan is arranged on one side of the first water tank, an EGR cooler is connected with the first water tank through a first water pump, an EGR cooler outlet water temperature sensor is arranged on a water outlet pipe of a heat exchange component, and an EGR cooler cold air temperature sensor is arranged on a connecting pipeline of the EGR cooler and the engine; the EGR cooler outlet water temperature sensor, the EGR cooler cold air temperature sensor and the first fan are separately connected with a controller, the controller acquires the EGR cooler outlet water temperature through the outlet water temperature sensor, and the controller acquires an abnormal combustion condition of the engine.

Description

TECHNICAL FIELD

[0001] The present application relates to the engine technical field, especially a cooling system capable of controlling EGR exhaust gas humidity. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] EGR: exhaust gas recirculation system, part of the exhaust gas discharged by the engine is sent back to the intake manifold after cooling, and mixed with fresh air before entering the cylinder, which reduces the cylinder combustion temperature, EGR exhaust gas usually enters the engine cylinder after passing through the EGR cooler, and the EGR cooler needs to provide circulating water through the water tank, the EGR cooler and the engine share a water tank in the prior art, the water tank of the EGR cooler is not separately provided, and the temperature of the EGR cooled gas cannot be adjusted separately, if adjustment is needed, the fan of the engine cooling water tank needs to be adjusted, once the adjustment is made, because the EGR cooler and the engine share the same water tank, it is easy to affect the temperature of other systems of the engine, thereby affecting the combustion of the engine.

[0004] In addition, in the prior art, when knock or misfire occurs in the engine, the engine speed is usually adjusted, or the engine intake is changed, because there is no suitable adjustment means, and the adjustment of the EGR exhaust gas temperature entering the engine cylinder is not considered. SUMMARY

[0005] In view of the deficiencies in the prior art, the purpose of the present application is to provide a cooling system capable of controlling EGR exhaust gas humidity, which ensures good combustion of the engine.

[0006] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme:

[0007] A cooling system capable of controlling EGR exhaust gas humidity, comprising a first water tank located in the engine compartment, the first water tank being independent of a second water tank for engine cooling, a first fan being arranged on one side of the first water tank, an EGR cooler being connected with the first water tank through a first water pump, an EGR cooler outlet temperature sensor being arranged on the outlet pipe of the heat exchange component, and an EGR cooler cold gas temperature sensor being arranged on the connecting pipeline between the EGR cooler and the engine.

[0008] The EGR cooler outlet temperature sensor, the EGR cooler cold gas temperature sensor and the first fan are respectively connected with a controller, the controller being an engine general controller, and the controller acquires abnormal combustion conditions of the engine.

[0009] The cooling system capable of controlling the humidity of EGR exhaust gas as described above, the controller obtains the water outlet temperature of the EGR cooler through the water outlet temperature sensor, the controller obtains the temperature of the air after being cooled by the EGR cooler through the air temperature sensor after being cooled by the EGR cooler, and the controller controls the operation of the first fan according to the water outlet temperature of the EGR cooler and the temperature of the air after being cooled by the EGR cooler.

[0010] The cooling system capable of controlling the humidity of EGR exhaust gas as described above, the controller controls the operation of the first fan according to the information sent by the water outlet temperature sensor of the EGR cooler and the air temperature sensor after being cooled by the EGR cooler, so that the temperature of the air after being cooled by the EGR cooler is between 40℃ and 70℃, and the EGR exhaust gas entering the cylinder of the engine is controlled to be in a range with low water content.

[0011] The cooling system capable of controlling the humidity of EGR exhaust gas as described above, considering that there are many structural members in the engine compartment, the first water tank also needs to be naturally cooled, the first water tank is located on one side of the second water tank, and the first water tank is located behind the air inlet grille in the engine compartment.

[0012] Since the first water tank is mainly used for cooling the EGR cooler, the volume of the first water tank is smaller than that of the second water tank.

[0013] The cooling system capable of controlling the humidity of EGR exhaust gas as described above, the first fan is located in front of and / or on the side of the first water tank.

[0014] The first fan is independent of the second fan for the second water tank.

[0015] The cooling system capable of controlling the humidity of EGR exhaust gas as described above, a pipeline is arranged between the EGR cooler and the first water tank, the pipeline comprises a plurality of sectional pipes, adjacent two sectional pipes are connected through a connecting pipe, and the heat exchange fins are arranged to effectively ensure the heat exchange effect of the heat exchange component on the EGR cooler.

[0016] The cooling system capable of controlling the humidity of EGR exhaust gas as described above, in order to realize the installation of the first water tank, a mounting piece is fixed to the side of the first water tank, the mounting piece is provided with a mounting hole, a fastener passes through the L-shaped support rod and the mounting hole of the mounting piece to fix the first water tank, and the L-shaped support rod is fixed to the engine.

[0017] In a second aspect, the application further provides an engine comprising the cooling system capable of controlling the humidity of EGR exhaust gas, a drain valve is arranged between the engine and the EGR cooler, and the EGR exhaust gas is drained from the drain valve after the EGR cooler and then enters the air intake pipe.

[0018] An engine as described above, the engine's air intake pipeline is provided with a turbocharger, the turbocharger is provided with an intercooler, the intercooler is provided with a cooling fan;

[0019] The intercooler gas outlet is provided with an intercooler outlet temperature sensor, and the controller is connected with the cooling fan of the intercooler and the intercooler outlet temperature sensor respectively.

[0020] In a third aspect, the application also provides a method for controlling the humidity of EGR exhaust gas, which uses the engine, and includes the following contents:

[0021] When the engine is working normally, the controller obtains the EGR cooler outlet water temperature through the outlet water temperature sensor, the controller obtains the EGR cooler cooled gas temperature through the EGR cooler cooled gas temperature sensor, and the controller controls the action of the first fan according to the EGR cooler outlet water temperature and the EGR cooler cooled gas temperature.

[0022] When the controller detects that the engine knocks, the controller controls the intercooler fan to increase the rotating speed, reduces the intercooler outlet temperature, at the same time, the controller controls the first fan to increase the rotating speed, reduces the EGR cooler cooled gas temperature, reduces the water content of the EGR cooler outlet gas, and improves the combustion condition of the engine; through the simultaneous adjustment of the intercooler and the first fan, the temperature response is faster, the engine cylinder inlet temperature is quickly reduced, the control sensitivity is higher, and the knocking tendency of the engine is effectively reduced.

[0023] When the controller detects that the engine misfires, the controller controls the intercooler fan to reduce the rotating speed, increases the intercooler outlet temperature, at the same time, the controller controls the first fan to increase the rotating speed, continues to reduce the EGR cooler cooled gas temperature, so that the engine cylinder inlet temperature is maintained within a set temperature range, to reduce the water content of the inlet gas and reduce the misfire tendency.

[0024] The beneficial effects of the application are as follows:

[0025] 1) In the application, the EGR cooler is provided with a first water tank for cooling the EGR cooler, so that the EGR cooler cooled gas temperature can be further controlled, the controller can directly control the first fan to adjust the EGR cooler cooled gas temperature, the first water tank and the first fan are both used for the EGR cooler and are not affected by other components, which facilitates the adjustment of the water content of the EGR exhaust gas and ensures the accuracy of the adjustment, the greater the rotating speed of the first fan, the lower the EGR cooler cooled gas temperature, and the water content of the EGR exhaust gas is effectively controlled, which can effectively improve the combustion condition of the engine.

[0026] 2) The EGR cooler after-cooling gas temperature is obtained by the EGR cooler after-cooling gas temperature sensor in the application, the controller controls the action of the first fan according to the EGR cooler outlet water temperature and the EGR cooler after-cooling gas temperature, so that the EGR cooler after-cooling gas temperature is within the set range, the water content of the EGR exhaust gas is effectively reduced, the combustion is improved, the water content of the engine oil is effectively reduced, the lubrication is improved, and the service life of the engine oil and the friction pair is improved.

[0027] 3) The first water tank is reasonably arranged in the engine compartment in the application, and the first water tank is located on one side of the second water tank for engine cooling, so that the front side of the first water tank is the windward side, which is beneficial to cooling the first water tank, and the first water tank and the second water tank can be filled with water at the same time, which is convenient for maintenance.

[0028] 4) When the engine knocks or misfires, the controller can effectively adjust the speed of the intercooler, adjust the outlet gas temperature of the intercooler, control the speed of the first fan, and reduce the EGR cooler after-cooling gas temperature to effectively reduce the water content of the EGR cooler outlet gas, while ensuring that the engine cylinder inlet gas temperature is sufficient, the intercooler and the EGR cooler are synchronously adjusted, the temperature response is faster, and the engine combustion condition is quickly improved, so that the power and economy of the engine are improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] The drawings accompanying the specification of the application form a part of the application and serve to provide further understanding of the application, the exemplary embodiments of the application and the description thereof serve to explain the application, and do not constitute an improper limitation on the application.

[0030] Figure 1 is a front view of a cooling system capable of controlling the humidity of EGR exhaust gas according to one or more embodiments of the application.

[0031] In the drawings, the mutual distance or size is exaggerated to show the position of each part, and the schematic diagram is only schematic. DETAILED DESCRIPTION

[0032] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise specified, all technical and scientific terms used in the application have the same meaning as generally understood by those skilled in the art to which the application belongs.

[0033] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0034] As introduced in the background, the prior art cannot directly control the EGR exhaust gas humidity alone, in order to solve the above technical problems, the present application provides a cooling system capable of controlling EGR exhaust gas humidity.

[0035] Embodiment one

[0036] In a typical embodiment of the present application, referring to Figure 1 A cooling system capable of controlling EGR exhaust gas humidity, comprising a first water tank located in the engine compartment, the first water tank is independent of the second water tank for engine cooling, a first fan is arranged on one side of the first water tank, an EGR cooler is connected with the first water tank through a first water pump, an EGR cooler outlet water temperature sensor is arranged on the outlet pipe of the heat exchange component, and an EGR cooler cold gas temperature sensor is arranged on the connecting pipeline between the EGR cooler and the engine.

[0037] The EGR cooler outlet water temperature sensor, the EGR cooler cold gas temperature sensor and the first fan are respectively connected with a controller, the controller obtains the EGR cooler outlet water temperature through the outlet water temperature sensor, the controller is an engine general controller (an existing engine controller), and the controller obtains the abnormal combustion condition of the engine.

[0038] The controller obtains the EGR cooler cold gas temperature through the EGR cooler cold gas temperature sensor, and the controller controls the action of the first fan according to the EGR cooler outlet water temperature and the EGR cooler cold gas temperature.

[0039] The controller controls the action of the first fan according to the information sent by the EGR cooler outlet water temperature sensor and the EGR cooler cold gas temperature sensor, so that the EGR cooler cold gas temperature is between 40℃ and 70℃, and the EGR exhaust gas entering the engine cylinder is controlled in a range with lower water content.

[0040] Considering that there are many structural components in the engine compartment, the first water tank also needs to be naturally cooled, the first water tank is located on one side of the second water tank, and the first water tank is located behind the air inlet grille of the engine compartment.

[0041] Since the first water tank is mainly used for cooling the EGR cooler, the volume of the first water tank is smaller than that of the second water tank.

[0042] In the embodiment, considering that the space between the first water tank and the engine is relatively narrow, the first fan is located in front of the first water tank, or the first fan is located on the side of the first water tank, and when a plurality of first fans are provided, the plurality of first fans can be arranged on both sides of the first water tank, so that the first water tank can be rapidly cooled by using natural wind and the first fan.

[0043] It can be understood that the first fan for cooling and adjusting the first fan in the embodiment is a separate component independent of the second fan for the second water tank; the first fan and the second fan can have the same structure, both of which are electronic fans and can be controlled by the controller.

[0044] Regarding the installation of the first water tank, the engine housing or the frame is provided with an L-shaped support rod, the first water tank is fixed to the L-shaped support rod, and both sides of the L-shaped support rod are connected with the engine housing or the frame. In order to realize the installation of the first water tank, the side and the bottom of the first water tank are both fixed with mounting pieces, the mounting pieces are provided with mounting holes, and fasteners such as bolts are locked through nuts after passing through the mounting holes of the L-shaped support rod and the mounting pieces to fix the first water tank. When the first fan is located in front of the first water tank, the first fan can be installed on the frame of the engine compartment through the L-shaped support frame; when the first fan is arranged on the side of the first water tank, the first fan is also supported by the frame, that is, the L-shaped support frame provided on the frame is located on the side of the first water tank.

[0045] It can be easily understood that a pipeline is arranged between the EGR cooler and the first water tank, the pipeline includes a plurality of segmented pipes, and adjacent two segmented pipes are connected through a connecting pipe. The segmented pipe and the connecting pipe can be flexible pipes to adapt to the narrow space in the engine compartment. The connecting pipe and the segmented pipe are connected by clamping, and the inner diameter of the connecting pipe is the same as the outer diameter of the corresponding side segmented pipe, so that the segmented pipe is clamped into one side of the connecting pipe.

[0046] In addition, the engine is provided with an engine water pump for supplying cooling water in the second water tank to the engine for cooling. An engine outlet water temperature sensor is arranged at the engine water pump to obtain the engine outlet water temperature and feed back to the controller. If the engine outlet water temperature is too high, the second fan is controlled by the controller to increase the rotating speed. The second water tank and the second fan are prior art and will not be described here. Considering that the first water tank is arranged on one side of the second water tank, the volume of the second water tank in the prior art can be appropriately reduced.

[0047] The saturated vapor pressure refers to the vapor pressure when the number of molecules evaporated and condensed per unit time of a liquid is saturated at a fixed temperature and pressure. It can be known from the calculation formula of the saturated vapor pressure in the prior art that the higher the gas temperature, the higher the water content. Therefore, by reducing the temperature of the EGR cooling gas, the water content of the EGR exhaust gas can be effectively reduced, and the combustion of the engine can be improved.

[0048] The cooling system provided by the embodiment is used for the EGR cooler alone, so that the controller can adjust the rotating speed of the first fan according to the EGR cooler outlet water temperature and the EGR cooler cooled gas temperature, so as to ensure that the EGR cooler cooled gas temperature, that is, the temperature of the EGR exhaust gas, is within a proper range when the engine is normally working, that is, the water content of the EGR exhaust gas is ensured. Through the control of the water content of the EGR exhaust gas, the combustion can be effectively improved, and the power and economy can be improved. For example, when the engine is working at 1200 rpm and 80% load rate, the engine outlet water temperature is 90℃, the EGR cooler cooled gas temperature is 80℃, the EGR cooler outlet water temperature is 70℃, the rotating speed of the first fan is increased to increase the rotating speed of the first fan, the EGR cooler water temperature is reduced to 55℃, the EGR cooler cooled gas temperature is reduced to 65℃, and the EGR exhaust gas is discharged from the water drain valve after the EGR cooler and then enters the intake pipe.

[0049] The EGR exhaust gas water content is effectively reduced based on the closed-loop control of the EGR cooler cooled gas temperature, the engine combustion is ensured to be good, the water content of the engine oil can be reduced, the lubrication can be effectively improved, the service life of the friction pair and the engine oil can be improved, and the risk of engine oil emulsification can be reduced.

[0050] Embodiment two

[0051] The embodiment provides an engine, which comprises the cooling system capable of controlling EGR exhaust gas humidity in embodiment one, an existing water drain valve is arranged between the engine and the EGR cooler, and the EGR exhaust gas is discharged from the water drain valve after the EGR cooler and then enters the intake pipe.

[0052] The intake pipe of the engine is provided with a turbocharger mechanism, the turbocharger mechanism is provided with an intercooler, and the intercooler is provided with a cooling fan;

[0053] An intercooler outlet gas temperature sensor is arranged at the gas outlet of the intercooler, and the controller is connected with the cooling fan of the intercooler and the intercooler outlet gas temperature sensor.

[0054] Embodiment three

[0055] The embodiment provides a method capable of controlling EGR exhaust gas humidity, and the method comprises the engine in embodiment two.

[0056] When the engine is normally working, the controller obtains the EGR cooler outlet water temperature through the outlet water temperature sensor, the controller obtains the EGR cooler cooled gas temperature through the EGR cooler cooled gas temperature sensor, and the controller controls the action of the first fan according to the EGR cooler outlet water temperature and the EGR cooler cooled gas temperature.

[0057] When the controller detects that the engine knocks, the controller controls the intercooler fan to increase the rotating speed, reduces the temperature of the outlet gas of the intercooler, at the same time, the controller controls the first fan to increase the rotating speed, reduces the temperature of the outlet gas of the EGR cooler, reduces the water content of the outlet gas of the EGR cooler, and improves the combustion condition of the engine; through the simultaneous adjustment of the intercooler and the first fan, the temperature response is faster, the engine cylinder inlet air temperature is quickly reduced, the control sensitivity is higher, the knocking tendency of the engine is effectively and quickly reduced; after the knocking problem is solved, the controller adjusts the rotating speed of the intercooler fan and the first fan according to the temperature information fed back by the EGR cooler outlet gas temperature sensor, so as to ensure the inlet air temperature of the engine cylinder;

[0058] When the controller detects that the engine misfires, the controller moderately controls the intercooler fan to reduce the rotating speed, increases the temperature of the outlet gas of the intercooler, at the same time, the controller controls the first fan to increase the rotating speed, the increase value of the rotating speed of the first fan is greater than that of the intercooler cooling fan, continues to reduce the temperature of the outlet gas of the EGR cooler, so that the engine cylinder inlet air temperature is kept in the set temperature range, so as to reduce the water content of the inlet air and reduce the misfire tendency.

[0059] The method provided in the embodiment moderately reduces the water content of the EGR exhaust gas when the engine knocks or misfires, reduces the reliability risk caused by the failure of other parts or systems, and flexibly controls the engine economy and reliability boundary.

[0060] Wherein, the misfire diagnosis: the controller of the engine judges whether the engine misfires according to the proportion of the number of misfire cycles in a plurality of cycles;

[0061] Knocking refers to the phenomenon that the unburned mixture spontaneously ignites before the flame generated by the spark plug ignites spreads, the spontaneous ignition wave collides with the normal combustion wave, and a great pressure shock wave is generated in the cylinder, and the shock wave repeatedly impacts on the cylinder wall. The engine cylinder is provided with a gas pressure sensor, and the engine controller receives the data sent by the gas pressure sensor to judge whether the engine cylinder knocks.

[0062] Take 1200rpm&2000Nm as an example, the intake air in the cylinder is composed of two parts, fresh air cooled by the intercooler (50℃), and EGR exhaust gas cooled by the EGR cooler (100℃), the temperature of the mixture is about 60℃ after mixing, the EGR exhaust gas flow is about 105kg / h, at this time the water content in the EGR exhaust gas is about 16kg / h, based on the calculation of saturated vapor pressure, the moisture content of the mixture at 60℃ is about 130g / kg, at this time the water in the EGR exhaust gas cannot be precipitated, at this time increase the cooling capacity of the EGR cooler (increase the speed of the first fan), the temperature of the gas cooled by the EGR cooler is reduced to 40℃, at this time the moisture content in the exhaust gas is reduced to 50g / kg, at this time nearly 60% of the water in the exhaust gas can be precipitated, these water is discharged through the water discharge valve before mixing, the speed of the fresh air cooling fan is reduced to increase the temperature of the fresh air to 65℃, to ensure that the temperature of the mixed engine intake air in the cylinder remains unchanged, still 60℃.

[0063] When the controller detects that the knock intensity exceeds the standard threshold value, the speed of the intercooler cooling fan and the speed of the first fan can be coupled and regulated to ensure simultaneous adjustment of the two-stage temperature, which can reduce the temperature of the intake air in the cylinder more quickly, reduce the knock tendency, and effectively protect the engine.

[0064] When the controller detects that the misfire rate exceeds the standard threshold value, the speed of the first fan is increased to reduce the temperature of the gas cooled by the EGR cooler, for example, from 40℃ to 30℃, which can further remove 5% to 10% of the moisture and increase the temperature of the gas cooled by the intercooler, which can improve the misfire condition of the engine.

[0065] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A cooling system for controlling the humidity of EGR exhaust gas, characterized in that, The first water tank is located in the engine compartment and is independent of the second water tank for engine cooling. A first fan is arranged on one side of the first water tank. An EGR cooler is connected to the first water tank by a first water pump. An EGR cooler outlet water temperature sensor is arranged on a water outlet pipe of the heat exchange component. An EGR cooler cold gas temperature sensor is arranged on a connecting pipeline of the EGR cooler and the engine. The EGR cooler outlet water temperature sensor, the EGR cooler cold gas temperature sensor, and the first fan are individually connected to the controller. The controller obtains the EGR cooler outlet water temperature through the outlet water temperature sensor. The controller is an engine general controller. The controller obtains the abnormal combustion condition of the engine. A turbocharger mechanism is arranged on an air inlet pipeline of the engine. A charge air cooler is arranged on the turbocharger mechanism. The charge air cooler has a cooling fan. A charge air cooler gas outlet temperature sensor is arranged on a gas outlet of the charge air cooler. The controller is connected to the cooling fan of the charge air cooler and the charge air cooler gas outlet temperature sensor. When the engine is normally working, the controller obtains the EGR cooler outlet water temperature through the outlet water temperature sensor. The controller obtains the EGR cooler cold gas temperature through the EGR cooler cold gas temperature sensor. The controller controls the action of the first fan according to the EGR cooler outlet water temperature and the EGR cooler cold gas temperature. When the controller detects that the engine has knock, the controller controls the charge air cooler fan to increase the rotating speed and reduce the charge air cooler outlet gas temperature. At the same time, the controller controls the first fan to increase the rotating speed and reduce the EGR cooler cold gas temperature, so as to reduce the water content of the EGR cooler outlet gas and improve the combustion condition of the engine. When the controller detects that the engine has misfire, the controller controls the charge air cooler fan to reduce the rotating speed and increase the charge air cooler outlet gas temperature. At the same time, the controller controls the first fan to increase the rotating speed and continue to reduce the EGR cooler cold gas temperature, so that the inlet gas temperature of the engine cylinder is kept within a set temperature range, so as to reduce the water content of the inlet gas and reduce the misfire tendency.

2. The cooling system of claim 1, wherein, The controller obtains the EGR cooler cold gas temperature through the EGR cooler cold gas temperature sensor. The controller controls the action of the first fan according to the EGR cooler outlet water temperature and the EGR cooler cold gas temperature.

3. The cooling system of claim 2, wherein the cooling system is configured to control the humidity of the EGR exhaust gas. The controller controls the action of the first fan according to the information sent by the EGR cooler outlet water temperature sensor and the EGR cooler cold gas temperature sensor, so that the EGR cooler cold gas temperature is between 40℃ and 70℃.

4. The cooling system of claim 1, wherein, The first water tank is located on one side of the second water tank and behind the air inlet grille in the engine compartment. The volume of the first water tank is smaller than that of the second water tank.

5. The cooling system of claim 1, wherein, The first fan is located in front of and / or on the side of the first water tank. The first fan is independent of the second fan for the second water tank.

6. The cooling system of claim 1, wherein, A pipeline is arranged between the EGR cooler and the first water tank. The pipeline includes multiple segmented pipes. Adjacent two segmented pipes are connected by a connecting pipe.

7. The cooling system of claim 1, wherein the cooling system is configured to control the humidity of the EGR exhaust gas. An installation piece is fixed on the side of the first water tank. The installation piece is provided with an installation hole. A fastener passes through the L-shaped support rod and the installation hole of the installation piece to fix the first water tank. The L-shaped support rod is fixed to the engine.

8. An engine characterized by, A cooling system for controlling the humidity of EGR exhaust gas as claimed in any one of claims 1 to 7, wherein a drain valve is provided between the engine and the EGR cooler.

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