JP2018135825A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine in which a foreign matter such as a particulate matter hardly deposits in an exhaust gas recirculation mechanism.SOLUTION: An internal combustion engine 1 includes: an intake channel 3 for introducing an intake gas to a combustion chamber 2; an exhaust gas passage 3 for discharging an exhaust gas from the combustion chamber 2; and an exhaust gas recirculation mechanism 5 having EGR passage 50 for returning part of an exhaust gas as EGR gas 5 g to the exhaust passage 3. The exhaust passage 4 includes a bent part 40. The GR passage 50 includes an inlet port 53 for EGR gas 5 g connected to an inside of a bent part of the bent part 40.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an internal combustion engine having an exhaust gas recirculation mechanism.

  In recent years, an exhaust gas recirculation mechanism (EGR) has attracted attention as a technique for reducing the amount of NOx produced. The exhaust gas recirculation mechanism includes an EGR passage that returns a part of the exhaust gas discharged from the combustion chamber to the intake passage as EGR gas. By introducing EGR gas into the combustion chamber, the amount of oxygen in the combustion chamber is reduced and the combustion temperature is lowered, so that the amount of NOx produced is reduced.

  Exhaust gas from diesel engines and direct-injection gasoline engines that inject fuel directly into the combustion chamber contains foreign substances such as particulate matter of various sizes (for example, soot) and unburned fuel. . These foreign substances are introduced into the combustion chamber through the EGR passage and burned. In Patent Document 1, a spiral flow path is set in the exhaust path, the particulate matter is unevenly distributed by centrifugal force, exhaust gas having a reduced concentration of the particulate matter is discharged to the atmosphere, and the concentration of the particulate matter is reduced. A technique for returning the exhaust gas that has risen to the EGR passage as EGR gas is disclosed.

JP 2010-276012 A

  In the configuration of Patent Document 1, since the particulate matter is unevenly distributed in the EGR gas, foreign matters such as the particulate matter are likely to be deposited over time in the EGR passage and the EGR valve. Particulate matter having a large particle size is likely to accumulate in the EGR passage and the EGR valve, and depending on the driving condition of the vehicle, a particulate matter having a large particle size may be easily generated in the exhaust gas. If the amount of accumulated foreign matter increases, it becomes difficult to adjust the amount of EGR gas, which may cause problems such as deterioration in emissions and fuel consumption.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide an internal combustion engine in which foreign matter such as particulate matter is difficult to accumulate in an exhaust gas recirculation mechanism.

An internal combustion engine according to one aspect of the present invention is
An intake path for introducing intake gas into the combustion chamber;
An exhaust path for exhausting exhaust gas from the combustion chamber;
An exhaust gas recirculation mechanism having an EGR passage for returning a part of the exhaust gas as EGR gas to the intake system path,
The exhaust path includes a bent portion,
The EGR passage includes an inlet of the EGR gas connected to the inside of the bent portion.

As one form of the internal combustion engine,
A form provided with the particulate filter which is provided in the downstream of the above-mentioned bent part in the above-mentioned exhaust course, and collects the particulate matter contained in the above-mentioned exhaust gas can be mentioned.

  By forming the bent portion in the exhaust path, a centrifugal force directed to the outside of the bent portion acts on the particulate matter contained in the exhaust gas. Since the centrifugal force increases as the diameter and weight of the particulate matter increases, the particulate matter having a large particle size tends to be closer to the outside of the bent portion. Here, in the configuration of the internal combustion engine, since the inlet of the EGR passage is connected to the inside of the bending portion, it is difficult for a particulate matter having a large particle size to be taken into the EGR passage. Therefore, in the internal combustion engine, it is difficult for particulate matter to accumulate in the EGR passage and the EGR valve.

  By disposing the particulate filter downstream of the bent portion, particulate matter having a large particle size distributed by the bent portion can be collected, and exhaust gas released to the atmosphere can be cleaned.

1 is a schematic configuration diagram of an internal combustion engine according to a first embodiment. FIG. 2 is a schematic configuration diagram in the vicinity of a bent portion in the exhaust path of the internal combustion engine of the first embodiment.

  Hereinafter, an embodiment of an internal combustion engine of the present invention will be described based on the drawings. In addition, this invention is not limited to these illustrations, is shown by the claim, and it is intended that all the changes within the meaning and range equivalent to a claim are included.

<Embodiment 1>
As shown in the schematic configuration diagram of FIG. 1, the internal combustion engine 1 burns the air-fuel mixture in the combustion chamber 2 to reciprocate a piston (not shown), and converts the reciprocating motion of the piston into rotational motion by a crankshaft (not shown). It is a heat engine. The internal combustion engine 1 includes an intake passage 3 that introduces an air-fuel mixture into the combustion chamber 2 and an exhaust passage 4 that discharges exhaust gas from the combustion chamber 2. A catalyst device 6 that decomposes hydrocarbons and carbon monoxide contained in the exhaust gas and a particulate filter 7 that collects particulate matter contained in the exhaust gas are provided in the middle of the exhaust path 4. The internal combustion engine 1 of this example further includes an exhaust gas recirculation mechanism (EGR) 5 that returns a part of the exhaust gas to the intake passage 3.

  The exhaust gas recirculation mechanism 5 includes an EGR passage 50, an EGR valve 51, and an EGR cooler 52. The EGR passage 50 communicates with the exhaust passage 4 and the intake passage 3, and returns a part of the exhaust gas discharged from the combustion chamber 2 to the intake passage 3 as the EGR gas 5g. The EGR valve 51 adjusts the amount of EGR gas 5 g introduced into the intake path 3. The EGR cooler 52 is configured to cool 5 g of EGR gas, and a known one can be used. By using the EGR cooler 52, it is possible to suppress that the intake gas including the EGR gas 5g expands at a high temperature and the amount of oxygen introduced into the combustion chamber 2 is reduced.

  In the internal combustion engine 1 of the present example, among the particulate substances contained in the exhaust gas, the particulate matter having a large particle size is made difficult to be introduced into the EGR passage 50, so that Foreign matter containing particulate matter is difficult to deposit. The specific configuration will be described below.

  As one configuration for suppressing the accumulation of foreign matter in EGR, in the internal combustion engine 1 of this example, a bent portion 40 is provided at a portion connecting the catalyst device 6 and the particulate filter 7 in the exhaust passage 4. The bent portion 40 in this example is a pipe line bent into an S shape with a predetermined radius of curvature. By providing the bent portion 40, as shown in FIG. 2, a centrifugal force directed to the outside of the bending acts on the particulate substances 8A and 8B. Since the centrifugal force increases depending on the mass, the particulate material 8A having a large particle size is more likely to be moved outside the bend than the particulate material 8B having a small particle size. Examples of the radius of curvature of the bent portion 40 include 3 cm or more and 10 cm or less.

  Here, since the bending part 40 is provided in order to apply a centrifugal force to the particulate matter and bring the particulate matter to the outside of the bend, it is not particularly limited as long as it has a shape capable of exhibiting its function. For example, the bent portion 40 may be formed in a spiral shape.

  As one configuration for suppressing the accumulation of foreign matter in the EGR, the internal combustion engine 1 of this example further connects the EGR passage 50 to the inside of the bent portion 40. By providing the EGR gas 5g inlet 53 inside the bend of the bent portion 40, as shown in FIG. 2, the particulate matter 8A having a large particle size brought close to the outside of the bend is hardly introduced into the EGR passage 50. Thus, the particulate matter 8B having a small particle diameter which is hardly brought to the outside of the bend is included in the EGR gas 5g.

≪Effect≫
As described above, since it is difficult for the EGR gas 5g to contain the particulate matter 8A having a large particle diameter, it is difficult for foreign matter to accumulate in the EGR passage 50 and the like. Further, since the particulate matter 8B introduced into the EGR passage 50 and fed into the combustion chamber 2 is fine, it is easy to burn in the combustion chamber 2. Therefore, it is possible to suppress inconveniences such as emission deterioration and fuel consumption reduction due to foreign matter accumulation. In addition, since the frequency of removing foreign matters can be reduced, the maintainability of the vehicle can be improved.

  On the other hand, the particulate matter 8A having a large particle diameter brought to the outside of the bend by the bent portion 40 is collected by the particulate filter 7 after passing through the bent portion 40. Therefore, the exhaust gas discharged from the internal combustion engine 1 of this example to the atmosphere is clean and the load on the environment is small.

  Further, in the internal combustion engine 1 of the present example, the particulate matter 8B having a small particle size is mainly introduced into the EGR passage 50, and the particulate matter 8A having a large particle size is mainly introduced into the particulate filter 7. Therefore, the vent hole diameter of the particulate filter 7 can be set large. When the vent hole diameter of the particulate filter 7 is increased, the pressure loss of the exhaust gas is reduced, so that a decrease in the torque of the internal combustion engine 1 due to the pressure loss of the exhaust gas can be suppressed.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Combustion chamber 3 Intake path 4 Exhaust path 40 Bending part 5 Exhaust gas recirculation mechanism (EGR) 5g EGR gas 50 EGR path 51 EGR valve 52 EGR cooler 53 Inlet 6 Catalytic device 7 Particulate filter 8A Particulate matter 8B Particulate matter with small particle size

Claims (2)

An intake path for introducing intake gas into the combustion chamber;
An exhaust path for exhausting exhaust gas from the combustion chamber;
An exhaust gas recirculation mechanism having an EGR passage for returning a part of the exhaust gas as EGR gas to the intake system path,
The exhaust path includes a bent portion,
The internal combustion engine, wherein the EGR passage includes an inlet of the EGR gas that is connected to the inside of the bent portion.   The internal combustion engine according to claim 1, further comprising a particulate filter that is provided downstream of the bent portion in the exhaust path and collects particulate matter contained in the exhaust gas.

Images