Egr-cooling device

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

In the present invention, a part of the exhaust gas is taken out from the exhaust system as exhaust gas recirculation (EGR) gas, and the EGR gas is guided to the EGR valve, the EGR valve that controls the EGR gas flow rate, and downstream of the EGR valve. It relates to an EGR cooling device that cools the EGR gas in the exhaust gas recirculation system, which is composed of an EGR pipe that guides the EGR gas to the intake system.

【0002】

[Conventional technology]

Cooling the EGR gas, which is mainly effective in reducing NOx, is the original purpose of the EGR, which is to suppress high-temperature combustion, improve cycle efficiency by increasing the amount of new intake air, and lower the environmental temperature in the engine room. It is known that it is highly effective in preventing thermal damage to harnesses, cords, and hoses. The disclosure technique of JP-A-9-88730 proposes a technique of wrapping a cold water pipe around the outer peripheral surface of an EGR pipe to cool the EGR gas. Although this technology can be expected to have a cooling effect on EGR gas, it lacks the ease of attaching a cold water pipe to the EGR pipe, and has the disadvantages that it is difficult to deal with the case of a pipe rupture. Further, in a method generally performed in which a jacket is put on a substantially straight pipe portion of an EGR pipe to cool the EGR pipe from the outer circumference, the cooling effect is limited by limiting the cooling range.

【0003】

[Problems to be Solved by the Invention]

The present invention has been proposed in view of the above-mentioned problems of the prior art, and harnesses, cords, hoses, etc. arranged in the periphery by reducing harmful exhaust gas by improving the cooling capacity of EGR gas and lowering the atmospheric temperature. It is intended to provide an EGR cooling system that prevents thermal damage in the air.

【0004】

[Means for solving problems]

The EGR cooling device of the present invention takes out a part of the exhaust gas as exhaust gas recirculation (EGR) gas from the exhaust system and guides the EGR gas to the EGR valve, an EGR valve that controls the EGR gas flow rate, and an EGR. In the EGR cooling device that cools the EGR gas in the exhaust gas recirculation system composed of the EGR pipe that guides the EGR gas to the intake system downstream of the valve, the first provided outside the pipe wall of the EGR duct. The cooling means of the above, the second cooling means provided outside the pipe wall in the vicinity of the EGR valve, and the third cooling means provided outside the pipe wall of the EGR pipe are included.

【0005】

In the EGR cooling device according to the present invention, the EGR gas is cooled in each part of the exhaust gas recirculation system by the first, second and third cooling means, so that the EGR cooling device is compared with the conventional EGR pipe cooling. [0006]

Well done, lowering the maximum combustion temperature.

【0007】

Further, the second cooling means is preferably formed in the EGR duct. According to this, the first cooling means outlet pipe can be connected to the second cooling water inlet pipe by a direct passage formed in the duct without using a pipe.

【0008】

Further, it is preferable that the second cooling means is formed in the EGR pipe. According to this, it is easy to provide a cooling means in the vicinity of the mounting portion of the EGR valve. Further, it is preferable that the water supply channel is separate from the third cooling means and the first and second cooling means. According to this, the improvement of the cooling effect by the parallel water supply can be utilized.

【0009】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the EGR cooling device of the present invention will be described with reference to the drawings. FIG. 1 shows a block configuration of an EGR cooling device that collectively refers to the entire invention by reference numeral 1, FIG. 2 shows a block configuration of a cooling water path flowing through the EGR cooling device 1, and FIGS. 3 and 4 show a description of FIG. Show the actual condition.

【0010】

This EGR cooling device 1 is composed of a first EGR pipe 6, an EGR duct (hereinafter abbreviated as a duct) 7 attached to the first EGR pipe, and a first cooling means formed in the duct 7. It contains a first water jacket 9, a second water jacket 14 which is a second cooling means connected to the first water jacket 9, and a third water jacket 18 which is a third cooling means. The main configuration consists of the second EGR pipe 13 and the EGR valve 8 mounted on the duct 7.

【0011】

The first EGR pipe 6 is connected to the exhaust manifold 4 provided on the engine exhaust side 2e via the block 3 (see FIG. 3) and is formed as a part of the duct 7, and the EGR gas Gr is sent to the engine intake side 2i. It is configured to guide. The duct 7 is formed so that the EGR gas Gr flowing in the pipe is cooled by the cooling water by the first water jacket 9 provided on the outer periphery of the pipe wall. The first water jacket 9 is connected to the cylinder head 20 (see FIG. 4) via the first cooling water inlet pipe 10 and the first cooling water outlet pipe 11. Further, as shown in FIG. 1, the duct 7 is formed by mounting an EGR valve 8 inside and providing a second water jacket 14 provided on the outer peripheral portion in the vicinity for cooling the EGR valve 8. There is.

【0012】

In the example shown in FIG. 3, the duct 7 contains the first water jacket 9, the EGR valve 8 is mounted on the second EGR pipe 13, and the second cooling water jacket 14 is also on the second EGR pipe 13. This is an example formed. In FIG. 3, a bellows-shaped portion 30 is formed in the second EGR tube 13 in order to absorb the fuel expansion and thermal contraction in the second EGR tube 13 or the vibration.

【0013】

In the second EGR pipe 13, a third water jacket 18 for cooling the EGR gas Gr flowing in the pipe is formed on the outer periphery of the pipe wall, and the third water jacket 18 has a second cooling water inlet pipe 15 and The second cooling water outlet pipe 16 is connected. The end of the second EGR pipe 13 is connected to the engine intake side 2i via the intake manifold 17. The first cooling water outlet pipe 11 may be directly connected to the second cooling water inlet pipe 15.

【0014】

Although each of the above cooling means depends on a water jacket, a cold water pipe may be attached to the pipe member.

【0015】

The operation of the EGR cooling device 1 having the above configuration will be described with reference to the cooling water path block of FIG. First, the cooling water W is discharged from the water pump, which is the water source of the engine cooling system (see block B1 and Fig. 4). Next, the engine oil is cooled by the oil cooler (block B2), and the cylinder etc. is cooled by entering the cylinder block (block B3). In this example, since it is a V-type engine, it is divided into two banks, left and right, and W / 2. And enter the cylinder head 2 (block B4). Then, from here, the cooling action of EGR gas Gr begins. Since the left and right have the same function, only the left bank will be explained.

【0016】

The cooling water W / 2 passing through the cylinder head 2 distributes the amount of water w1 to the third water jacket 18, which is the cooler of the second EGR pipe 13, and the amount of water w3 for the EGR valve 8 and the duct. In this case, w1 and w3 are the same amount. As shown in FIG. 4, the cooling water amount w1 cools the EGR gas Gr in the third water jacket 18 of the cooler of the second EGR pipe 13, the second jacket 14 in the EGR valve 8, and the duct 7 in the duct 7. The EGR gas Gr is cooled by the amount of cooling water w3 in the first jacket 9.

【0017】

In this way, the EGR gas Gr taken out from the exhaust manifold 4 is cooled by the first water jacket 9, the second water jacket 14, and the third water jacket 3, respectively, and is cooled by the engine 2 via the intake manifold 17. Returned to. The cooling water that cools the EGR gas Gr passes through the thermo housing (block B7) and the thermostat (block B8), and if the cooling water is above the specified high temperature, the total amount of water goes to the radiator to cool it, and it is below the specified low temperature. If so, most of it is returned to the water pump as it is, and if it is an intermediate temperature, it is distributed to both at the middle of valve opening and closing to become an appropriate temperature and acts in the engine cooling system and cools the EGR gas Gr.

【0018】

[Effect of the invention]

The effects of the present invention are listed below. (1) In the EGR cooling device of the present invention, the first cooling means provided outside the pipe wall of the EGR duct, the second cooling means provided outside the pipe wall in the vicinity of the EGR valve, and the EGR pipe. Since the EGR gas is cooled in each part of the exhaust gas recirculation system by the third cooling means provided outside the pipe wall, it is performed in a wider range than the conventional EGR pipe cooling alone, and the maximum combustion temperature is lowered and harmful. Exhaust gas emissions are reduced. In addition, since the temperature of the external atmosphere of each part of the system is lowered, thermal damage to harnesses, cords, hoses, etc. can be prevented, and installation of a heat shield plate or the like can be omitted. (2) If the second cooling means is formed in the EGR duct, a direct passage is formed in the duct from the first cooling means outlet pipe to the second cooling water inlet pipe without using piping. The shape is simple and the number of parts can be reduced. (3) If the second cooling means is formed in the EGR pipe, it is easy to provide the cooling means in the vicinity of the mounting portion of the EGR valve. (Four) If the water supply passages are separated from the third cooling means and the first and second cooling means, a cooling effect such as distributing a large amount of cooling water to a portion having a high cooling effect by distribution by parallel water supply, for example. Can be given.

[Simple explanation of drawings]

[Figure 1]

The block block diagram of the EGR cooling apparatus which shows embodiment of this invention.

[Figure 2]

Block diagram showing the cooling water path to the EGR cooling system in a V-type engine.

[Fig. 3]

The actual sectional view of FIG.

[Fig. 4]

The figure which shows the YY cross section of FIG.

[Explanation of symbols]

1 EGR cooling device 2 Engine 2e ... Engine exhaust side 2i ... Engine intake side 3 ... block 4 Exhaust manifold 6 1st EGR tube 7 Duct 8 EGR valve 9 1st water jacket 10 1st cooling water inlet pipe 11 First cooling water outlet pipe 13 Second EGR tube 14 Second water jacket 15 Second cooling water inlet pipe 16 Second cooling water outlet pipe 17 Intake manifold 18 Third water jacket 20 Cylinder head 30 Bellows-shaped piping