JP3491437B2 - Intercooler for turbocharged diesel engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention lowers the temperature of intake air of a diesel engine with a supercharger to improve the intake efficiency of air to maintain good engine combustion and lower the combustion temperature to reduce NOx emission. The present invention relates to an intercooler for a diesel engine with a supercharger that suppresses the generation of exhaust gas and improves the fuel efficiency and durability of the engine.

[0002]

2. Description of the Related Art In recent years, a vehicle equipped with a diesel engine with a supercharger to increase the power of the engine has been used. Furthermore, in order to improve the output of the engine, the supercharger pressurizes and raises the temperature. An intercooler that cools the temperature of the intake air is also provided.

This intercooler is classified into a water-cooled type and an air-cooled type, and as shown in FIG. 4, both are provided in an intake path connecting a supercharger and an intake manifold, and cool the intake air whose temperature has risen and burn it. By lowering the temperature of the intake air entering the room and improving the air filling efficiency, the amount of air increases and the fuel efficiency increases, so combustion can be improved, fuel efficiency can be improved, and maximum temperature and pressure can be increased. Since it can be reduced, the heat load and mechanical load of the engine can be reduced,
The durability of the engine can be improved.

On the other hand, in order to reduce the emission amount of NOx in the exhaust gas of the engine, a part of the exhaust gas which is an inert gas is recirculated to the intake air to suppress the combustion temperature and suppress the production of NOx. (Exhaust gas recirculation) is effective and widely used. In this EGR, as shown in FIG. 5, by putting the EGR gas upstream of the intercooler and cooling it together with the intake air, a larger amount of the EGR gas can be recirculated with the same gas volume, and the EGR rate can be increased. Therefore, the effect of reducing NOx in the exhaust gas can be increased.

The structure of the above-mentioned intercooler is as follows:
As disclosed in JP-A-0-24815, a diagram in which a tube forming a core is formed in a substantially quadrilateral main body having equal lengths, and an intake inlet and an intake outlet are formed at diagonal positions thereof. The configuration shown in FIG. 3 is preferable and general when considering the flow in each tube. However, since the intake / exhaust ports of the intercooler are close to the frame of the vehicle body and the engine hood, there may be a case where the intercooler having the structure as shown in FIG. 3 cannot be arranged. In such a case, it is difficult to redesign the vehicle and the hood due to the intercooler, because it causes an increase in cost. Usually, the intake air inlet is adjusted according to the layout of the engine room as shown in FIG. The intake and discharge ports are provided to face one side of the core.

[0006]

However, in the structure of the intercooler having a substantially quadrangular core shape using tubes of equal length as shown in FIG. 2, the inlet / outlet side A
As the distance from the inlet to the other side B farther from the inlet increases, the passage distance of the intake air gradually increases, and the flow resistance gradually increases correspondingly, making it difficult to flow. Therefore, the flow velocity in the tube gradually decreases accordingly.

In the portion where the flow velocity in the pipe is low, the inside of the pipe is contaminated due to the deposition of dust or the like during intake air, the pipe frictional resistance increases, and further the flow velocity and flow amount in the pipe decrease, causing a vicious cycle. In addition, since the flow rate and the flow velocity in the tube near the inlet / outlet side A increase accordingly,
Also in this portion, there is a problem that the pipe friction resistance increases, the passage resistance of the entire intercooler increases, which causes an increase in pumping loss at the time of intake and deteriorates fuel efficiency.

In particular, when cooling the EGR gas,
Soot in the EGR gas is accumulated in the tube having a low flow velocity in the pipe, and a low flow velocity portion (stagnation portion) is likely to occur. In this low flow velocity area, when the cooling water temperature of the cooler or the temperature is low, such as in the winter or immediately after the start of the engine, the mixture of EGR gas and air with a large amount of water vapor is cooled to below the dew point, and dew condensation occurs. It reacts with the sulfur oxides in it to generate sulfuric acid, which creates corrosion holes on the wall of the intercooler.
There is a problem in that the supercharging pressure of the engine is reduced due to intake air leakage, resulting in deterioration of fuel efficiency.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to make the flow velocity of the intake air in the tube of the intercooler substantially uniform to reduce the passage resistance of the intake air through the intercooler as a whole. In addition, it is to provide an intercooler for a diesel engine with a supercharger that can reduce fuel consumption by reducing pumping loss during intake. Also, E
When GR gas is cooled by the intercooler, the flow velocity of the intake air in the tube of the intercooler is made substantially uniform, the occurrence of dew condensation due to supercooling is suppressed, the sulfuric acid corrosion of the intercooler can be prevented, and the intake leak is caused. It is an object of the present invention to provide an intercooler for a diesel engine with a supercharger, which can prevent deterioration of fuel efficiency due to a decrease in supercharging pressure of the engine.

[0010]

In order to achieve the above object, in an intercooler provided in an intake pipe line connected to a supercharger of a diesel engine, the intercooler includes an inflow header and an inflow header. A discharge side header and a heat exchange core provided between the headers, and an intake inlet and an intake outlet provided in the header are arranged to face one side of the core, and The length of the tube forming the core gradually decreases from the one side toward the other side.

When the EGR gas is cooled by an intercooler, an EGR pipe that recirculates a part of engine exhaust gas to intake air is connected between the exhaust manifold of the engine and the intake pipe line upstream of the intercooler. Configure.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 shows an exhaust system and an intake system of a diesel engine with a supercharger using an intercooler. The engine 1 is provided with a supercharger (turbocharger) 4, and the outlet of the exhaust manifold 2 is driven by exhaust. The turbine 4a is provided, the compressor 4b on the driven side is connected to the intake pipe line 5, and the intake air sucked and pressurized from the intake inlet pipe line 13 is passed through the intake pipe line 5 provided with the intercooler 10. Combustion is improved by supplying it to the intake manifold 3 and cooling the intake air with this intercooler 10.

As shown in FIG. 1, the intercooler 10 is provided with an inlet side header 21 having an intake inlet port 20, a discharge side header 23 having an intake outlet port 24, and both headers 21, 23. The intake air inlet 20 and the intake air outlet 24 are arranged so as to face one side A of the core 22, and are located on substantially the same straight line. As shown in FIG. 6, the core 22 includes a tube 25 brazed to the end plates 27 at the header portions at both ends, and fins 26 provided between the end plates 27 to enhance cooling efficiency.
The intake air passes through the inside of the tube 25, and the coolant such as cooling water and the outside air passes between the fins 26.

The lengths of the tubes 25 are gradually reduced from the inlet / outlet side (one side) A to the opposite side (other side) B farther from the inlet / outlet side, and the flow velocity in each tube 25 causes contamination of the tubes. It is shortened until the flow velocity exceeds a predetermined value that can suppress the progress of. In this case, it is preferable to determine for each tube so that the flow rate in each tube 25 is substantially uniform under the intake condition where troubles are likely to occur, but the flow rate in the tube 25 near the inlet / outlet side A and the inlet / outlet The lengths of the tubes 25 at both ends are determined so that the flow velocities in the tubes 25 near the opposite side B are substantially the same, and the lengths of the tubes 25 in between are inserted so that the core 22 has a substantially trapezoidal shape. You may decide.

Further, a conventional substantially quadrilateral core as shown in FIG.
In 22, only the tube 25 near the tube 25 in which the low flow rate portion (stagnation portion) is generated may be shortened so as to be equal to or higher than a predetermined flow rate or approximately the same as the flow rate in the tube 25 near the inlet / outlet side A. . The relationship between the flow velocity inside the tube 25 and the length of the tube 25 can be easily obtained based on measurement and calculation.

In the intercooler 10 constructed as described above, the in-pipe frictional resistance of the tube 25 gradually decreases as the length of the tube 25 gradually decreases from the inlet / outlet side A toward the opposite side B. Further, as the length of the tube 25 gradually decreases, the passage cross-sectional areas of both headers 21 and 23 gradually increase from the inlet / outlet side A toward the opposite side B. The flow of intake air between can be smoothed.

Therefore, the tube near the side B opposite the doorway
Since the pipe frictional resistance is gradually reduced by about 25, the flow resistance in the intercooler including the flow resistance in the header part can be made approximately the same for the intake air passing through each tube 25, and the flow velocity in the pipe is made substantially uniform. As a result, it is possible to eliminate the low-velocity stagnation portion, reduce the passage resistance of the entire intake intercooler, reduce pumping loss during intake, and improve fuel efficiency.

Next, an embodiment for cooling the EGR gas will be described with reference to FIG. When performing EGR,
An EGR pipe line 7 is provided, one end of which is connected to the exhaust manifold 2, and the other end is the intake pipe line 5 on the upstream side of the intercooler 10.
Connect to. This EGR pipe is provided with an EGR valve 6 and is controlled by a controller (not shown).
Adjust the GR gas amount.

With the above-described structure, the EGR gas whose gas amount has been adjusted by the EGR valve 6 is supplied from the exhaust manifold 2 to the intake pipe 5 through the EGR pipe 7, and joins the intake air from the intake inlet pipe 13. Then, it is cooled by the intercooler 10 to enhance the EGR effect. Then, by adopting the intercooler 10 having the above-described configuration, the flow of the air-fuel mixture is made substantially uniform in each tube 25, and the stagnation portion of the low flow velocity is eliminated, so the exhaust gas is supercooled below the dew point. Water will be quickly sucked into the cylinder even if dew condensation occurs, so that the generation of sulfuric acid can be suppressed, and the occurrence of corrosion of the wall surface of the intercooler 10 and leakage of intake air due to it will not occur. Therefore, it is possible to prevent deterioration of fuel efficiency due to a decrease in supercharging pressure of the engine.

Regarding the cooling effect of the intercooler 10 of the present invention, although the cooling area is reduced by the shortening of the tube 25, the flow in the low flow velocity portion in the tube 25 is improved and the flow velocity is increased to increase the heat. Since the replacement amount, that is, the heat radiation amount of the intake air increases to compensate for the decrease in the cooling area, almost the same cooling effect can be obtained. Further, although the same effect can be obtained with respect to the flow rate by gradually increasing the tube diameter instead of gradually decreasing the length of the tube 25, the cooling effect is different.

[0021]

According to the invention of claim 1, the flow velocity of the intake air in the tube of the intercooler is made substantially uniform, the passage resistance of the intake air through the intercooler is reduced, and the pumping loss at the time of intake is reduced. Fuel efficiency can be improved. Also, E
When GR gas is cooled by the intercooler, the flow velocity of the intake air in the tube of the intercooler is made substantially uniform, the occurrence of dew condensation due to supercooling is suppressed, the sulfuric acid corrosion of the intercooler can be prevented, and the intake leak is caused. It is possible to prevent deterioration of fuel consumption due to a decrease in supercharging pressure of the engine.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an intercooler according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional intercooler.

FIG. 3 is a front view showing a conventional intercooler.

FIG. 4 is a system diagram of an engine showing an arrangement of intercoolers.

FIG. 5 is a system diagram of an engine showing an arrangement of an EGR device and an intercooler.

FIG. 6 is an enlarged perspective view of a portion of FIG. 1C showing the structure of the intercooler.

[Explanation of symbols]

1 Engine 2 Exhaust Manifold 3 Intake Manifold 4 Supercharger (Turbocharger) 5 Intake Pipe Line 6 EGR Valve 7 EGR Pipe 10 Intercooler 13 Intake Inlet Pipeline 14 Exhaust Outlet Pipeline 20 Inlet Inlet 21 Inlet Header 22 Core 23 Discharge side header 24 Intake discharge port 25 Tube 26 Fin 27 End plate 28 Drain plug

Claims (2)

(57) [Claims] 1. An intercooler (1) provided in an intake pipe line (5) connected to a supercharger (4) of a diesel engine.
In 0), the intercooler (10) includes an inflow header (21), a discharge header (23), and a heat exchange core (22) provided between the headers (21, 23). And the intake inlet (20) and the intake outlet (24) formed in the header (21, 23) are arranged to face one side (A) of the core (22). An intercooler for a diesel engine with a supercharger, wherein the length of a tube (25) forming (22) is gradually reduced from the one side (A) to the other side (B). 2. E for recirculating a part of engine exhaust gas to intake air
The intercooler for a diesel engine with a supercharger according to claim 1, wherein a GR pipe (7) is connected between an exhaust manifold (2) of the engine and an intake pipe line (5) upstream of the intercooler (10). .