JP2607175B2 - EGR device for turbocharged engine - Google Patents

Description

The present invention relates to an EGR device for a turbocharged engine, and in particular, drives an exhaust turbine by exhaust gas of an engine,
The present invention relates to an EGR device in an engine in which intake air is compressed and supercharged by a compressor directly connected to the exhaust turbine.

[Summary of the Invention]

In a turbocharged engine, the higher the supercharging, the higher the pressure on the intake side.
R control becomes difficult. Therefore, part of the exhaust gas extracted from the exhaust system is supplied to the low pressure part on the back of the impeller of the compressor of the turbocharger,
This is to achieve EGR.

[Conventional technology]

EGR (Exhaust Gas Recirculation) is known as one method for reducing the amount of nitrogen oxides in exhaust gas. The EGR is to return a part of the exhaust gas to the intake side, which increases the heat capacity of the intake air in the cylinder and lowers the relative oxygen concentration, so that the combustion becomes slower, The combustion temperature is lowered so that the production amount of nitrogen oxides is suppressed.

[Problems to be solved by the invention]

While such conventional EGRs can be easily incorporated into natural engines, they are difficult to combine with turbocharged engines. The reason is that supercharging by the turbocharger increases the pressure on the intake side and makes it difficult to control the amount of EGR using the intake pressure. In other words, a sufficient effect cannot be exerted only by arranging the EGR pipe between the exhaust system and the intake system.

Therefore, as shown in FIG. 4, the exhaust gas extracted from the downstream side of the exhaust turbine 21 of the turbocharger 20 is supplied to the EGR pipe 2
By 6 it is considered to return to the throttled portion which is an intermediate portion between the butterfly valve 28 and the impeller.

According to such a configuration, the EGR is performed such that the exhaust gas is returned to a portion on the upstream side of the compressor 22 and at a relatively low pressure, thereby increasing the circulation amount of the EGR gas, The butterfly valve 28 allows control of the control of the amount of EGR gas.

However, even in such a configuration, the compressor 22
Because the EGR gas is mixed with intake air upstream of the impeller, not only is the impeller of the compressor not only soiled with soot, but also the negative pressure on the rear side of the impeller cannot be used effectively, and There was a problem that the amount of EGR gas did not increase so much and the effect was poor.

The present invention has been made in view of such a problem, and an EGR device for a turbocharged engine in which an internal structure of a turbocharger is used to increase or control the amount of circulating EGR gas. It is intended to provide.

[Means for solving the problem]

The present invention is directed to an engine in which an exhaust turbine is driven by exhaust gas of an engine, and a compressor directly connected to the exhaust turbine compresses intake air to perform supercharging. A turbocharged engine, characterized in that it is connected to a wall opening of the compressor so as to face a rear part, and a part of exhaust gas extracted from an exhaust system is returned to a rear part of an impeller of the compressor. It is related to the EGR device.

[Action]

Therefore, the EG is connected by a pipe connected to the wall opening of the compressor so that the front end faces the back of the compressor.
R is performed, and the exhaust gas taken out of the exhaust system is sucked by the back surface of the impeller having a low pressure of the compressor and is taken into the intake side.

〔Example〕

FIG. 2 shows a turbocharged engine equipped with an EGR device according to one embodiment of the present invention. This engine
10 consists of a diesel engine. An intake manifold 11 and an exhaust manifold 12 are mounted on both sides of a cylinder block constituting the engine 10. The intake manifold 11 is divided into three cylinders, each of which is connected to an intake pipe 13. In contrast, the exhaust manifold 12 is connected to an exhaust pipe 14. An air cooler 15 is attached to the tip of the intake pipe 13, and the air cleaner 15 introduces air from the outside. On the other hand, a muffler 16 is connected to the end of the exhaust pipe 14, and exhaust gas is discharged into the atmosphere through the muffler 16.

Further, the engine 10 is constituted by a turbocharged engine, and is equipped with a turbocharger 20. The turbine 21 of the turbocharger 20 is connected between the exhaust manifold 12 and the exhaust pipe 14. On the other hand, the compressor 22 of the turbocharger 20 is connected to the intake pipe 13 between the air cleaner 15 and the intercooler 23.

An EGR pipe 26 is connected to the turbocharger 20. That is, as shown in FIG. 1, the EGR pipe 26 taken out of the turbocharger 20 from the downstream side of the turbine 21
Is connected to the low pressure portion on the rear side of the impeller of the compressor 22. Further, an electromagnetic valve 27 is connected to the EGR pipe 26. A butterfly valve 28 is connected to the upstream side of the compressor 22 of the turbocharger 20.
28 adjusts the amount of intake air.

In the above-described configuration, the exhaust gas generated by the combustion in each cylinder of the engine 10 is disposed in the exhaust manifold.
The gas is supplied to the turbine 21 of the turbocharger 20 through 12, and drives the turbine 21. After driving the turbine 21, the exhaust gas is discharged into the atmosphere through the muffler 16. A compressor 22 directly connected to the turbine 21 compresses intake air introduced through the air cleaner 15, and cools the intake air by an intercooler 23 to form an intake pipe 13 and an intake manifold.
It is supplied to each cylinder of the engine 10 through 11.

A part of the exhaust gas passing through the exhaust pipe 14 on the downstream side of the turbocharger 21 is taken out by the EGR pipe 26, and is introduced into the negative pressure region on the back side of the impeller of the compressor 22 through the electromagnetic valve 27. It has become. The exhaust gas is mixed with the intake air in the compressor 22 and supplied to each cylinder of the engine through the intercooler 23 and the intake pipe 13.

As described above, in the turbocharged engine according to the present embodiment, the exhaust gas discharged from the turbine 21 side of the turbocharger 20 is returned to the negative pressure region on the back side of the impeller of the compressor 22 on the intake side. I have. As a result, the air is mixed with the air discharged from the impeller of the compressor 22, and the exhaust gas is circulated to the intake side of the engine 10. That is, a part of the exhaust gas discharged from the turbine 21 of the turbocharger 20 is guided to the back side of the negative pressure region of the impeller of the compressor 22 on the opposite side, and mixed with air exiting from the compressor to perform EGR. It is. Therefore, while increasing the amount of EGR circulation,
Can be controlled. FIG. 3 shows a conventional EGR-enabled area and an EGR area enabled by the present invention, respectively. According to the present invention, it is shown that EGR in an area where the engine load is high is achieved. I have.

〔The invention's effect〕

As described above, the present invention connects the end of the pipe performing EGR to the wall opening of the compressor such that the front end faces the back of the compressor, and a part of the exhaust gas extracted from the exhaust system is connected to the back of the impeller of the compressor. It is to return to the department.

Therefore, according to the present invention, the exhaust gas is sucked by the negative pressure generated on the back surface of the impeller having a low pressure of the compressor and returned to the intake side so that the amount of the EGR gas can be increased. Can be controlled. Also, the soot in the EGR gas can be blown off by the centrifugal force generated by the rotation of the impeller, so that the impeller of the compressor is prevented from being stained by the soot.

[Brief description of the drawings]

FIG. 1 shows a turbocharged engine according to one embodiment of the present invention.
FIG. 2 is a sectional view of a main part of a turbocharger showing an EGR device, FIG. 2 is a plan view of a turbocharged engine equipped with the EGR device,
FIG. 3 is a graph showing an area where EGR is possible, and FIG.
It is principal part sectional drawing of the turbocharger which shows a GR apparatus. The names of the main parts in the drawings are as follows. 10 Engine (cylinder block) 13 Intake pipe 14 Exhaust pipe 20 Turbocharger 21 Turbine 22 Compressor 23 Intercooler 26 EGR pipe 27 Electromagnetic valve 28 Butterfly valve

Claims (1)

(57) [Claims] 1. An engine in which an exhaust turbine is driven by exhaust gas of an engine and a supercharger is performed by compressing intake air by a compressor directly connected to the exhaust turbine. A turbocharged engine connected to a wall opening of the compressor so as to face a rear surface of the compressor, and a part of exhaust gas extracted from an exhaust system is returned to a rear surface of an impeller of the compressor. EGR equipment.