JP2010065609A - Control method of engine with egr device and its air supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce NOx by supply of EGR gas, and to restrain generation of soot in combustion gas, in a diesel engine with an EGR device. <P>SOLUTION: Supply air is turned by a means for turning the supply air in the specific direction in an air supply port 108, and is supplied to a combustion chamber 103 of the engine. Gas of the low EGR concentration is held by distributing the supply air in an outer peripheral near part of the combustion chamber 103 by centrifugal force generated by turning of the supply air. The EGR gas is input to a central part of the combustion chamber 103, and the EGR concentration of the central part is held in the higher concentration than the outer peripheral near part. and fuel is sprayed thereby in a nonuniform air-fuel mixture from the combustion chamber central part by forming the nonuniform air-fuel mixture in the EGR concentration of the supply air and the EGR gas in the combustion chamber 103. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is mainly applied to a diesel engine with an EGR (exhaust gas recirculation) device, and an engine with an EGR device in a cylinder head provided with an EGR passage for extracting a part of the exhaust gas of the engine and returning it to an air supply port. The present invention also relates to a method for controlling such an engine with an EGR device.

FIG. 8 is a configuration diagram showing the overall configuration of a diesel engine with an EGR (exhaust gas recirculation) device used in Patent Document 1 (Japanese Patent No. 4108061) and the like.
In FIG. 8, exhaust gas combusted by a diesel engine (hereinafter referred to as engine) denoted by reference numeral 100 passes through an exhaust valve (not shown), an exhaust port (not shown) and an exhaust pipe 109s of each cylinder, and then exhausted. It is sent to the exhaust turbine 120 of the turbocharger 122 to drive the exhaust turbine 120.

On the other hand, the air compressed by the compressor 121 driven coaxially to the exhaust turbine 120 passes through the air supply pipe 125, is cooled by the air cooler 134, passes through the throttle valve 123, and is supplied to an air supply port (not shown) of each cylinder. And enters an air supply valve (not shown) through the air supply port.
Further, a part of the exhaust gas of the engine is extracted from the exhaust pipe 109s and returned to the air supply pipe 125 on the downstream side of the throttle valve 123 through the EGR passage 110 and the EGR cooler 124. The passage area of the EGR passage 110 is adjusted by the EGR valve 111a.

In Patent Document 1 (Patent No. 4108061) showing an example of such a diesel engine with an EGR device,
For example, as shown in FIG. 5 of the same publication (indicated by the reference numeral of the same publication), the engine air supply pressure is often higher than the engine exhaust pressure in the case of the engine with the exhaust turbocharger 102. The opening of the valve 108 is throttled to reduce the supply air pressure so that EGR gas can easily flow into the supply port.
In the diesel engine with the EGR device, as described above, the low-oxygen concentration EGR gas is mixed into the supply side, and low-oxygen concentration combustion is performed in the cylinder. When the oxygen concentration in the supply air decreases due to gas mixing, there is a problem that the increase in soot increases.

  Further, Patent Document 2 (Japanese Patent Laid-Open No. 2008-111374) discloses an EGR gas outlet passage that opens above the exhaust port 32 of the cylinder head 1a as shown in FIG. 10b and an EGR gas inlet passage 10a that opens upward from the air supply port 33. An EGR gas inlet passage 10a is provided between the EGR gas outlet passage 10b and the inlet passage 33a of the EGR gas inlet passage 10a. Are communicated by a gas reflux passage 10 formed in

Japanese Patent No. 4108061 JP 2008-111374 A

In a diesel engine with an EGR device, low-oxygen concentration EGR gas is mixed into the supply side, and low-oxygen concentration combustion is performed in the cylinder.
In such a diesel engine with an EGR device, when the oxygen concentration in the supply air decreases due to mixing of the EGR gas, soot increases greatly. In order to prevent such an increase in soot, it is necessary to distribute the supply air evenly throughout the combustion chamber to avoid the uneven combustion of EGR gas as well as NOx reduction by EGR gas.

That is, in an engine equipped with an EGR device, EGR gas for reducing NOx often stays in one corner of the combustion chamber, particularly in the outer periphery thereof, and fresh air (supply air) tends to be insufficient in this portion. Therefore, soot is likely to be generated in this portion due to the combustion of the EGR gas supplied to reduce NOx.
However, Patent Document 1 and Patent Document 2 do not disclose means for preventing wrinkles.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the diesel engine with an EGR device is to promote NOx reduction by supplying EGR gas and to promote combustion by preventing generation of soot in the combustion gas.

  The present invention solves such a problem, and an EGR device in a cylinder head having a fuel injection valve at the center of a cylinder of an engine and an EGR passage for extracting a part of exhaust gas and returning it to an intake port. In the attached engine control method, the supply air is swirled by means for swirling the supply air in a fixed direction and supplied to the combustion chamber of the engine, and the supply air is supplied to a portion of the combustion chamber closer to the outer periphery than the center of the cylinder. The supply air is distributed by the centrifugal force generated by the swirling of the gas to hold the gas having a low EGR concentration, and the EGR gas is injected into the central portion of the combustion chamber so that the EGR concentration at the central portion is closer to the outer periphery. A mixture having a non-uniform EGR concentration of the supply air and the EGR gas is formed in the combustion chamber, and fuel spraying is performed in the non-uniform mixture. You (Claim 1).

The following device is used in the method for controlling the engine with the EGR device.
(1) In an engine with an EGR device in a cylinder head, which is provided with a fuel injection valve at the center of the cylinder of the engine, and an EGR passage that extracts a part of exhaust gas and recirculates it to an air supply port.
A swirl flow generating means for swirling the supply air in a fixed direction in the combustion chamber, and the supply air flow flows in layers in the supply port toward the combustion chamber of the engine, and the EGR gas passes through the EGR passage. The air supply port is connected to the air supply port so as to flow toward the combustion chamber in the same direction as the layered air supply air and in a state where the layered air supply air is partly separated without mixing with the layered air supply air. (Claim 2).

(2) In an engine with an EGR device in a cylinder head, which is provided with a fuel injection valve in the center of the cylinder of the engine and which has an EGR passage that extracts a part of exhaust gas and recirculates it to an intake port, Swirling flow generating means for swirling air in a fixed direction, and opening the EGR passage into the air supply port so that EGR gas merges with the air supply air, and the opening into the air supply port. A throttle portion having a smaller area than the other portions is formed corresponding to the above, and the intake of EGR gas from the opening portion is promoted by the venturi effect of the throttle portion (claim 3).
In this invention, it is preferable that the throttle portion is formed in a protruding portion that projects a part of the peripheral wall in the air supply port that faces the opening.

  Further, in the device invention, preferably, two supply valves and two exhaust valves are provided side by side, and the EGR passage is led out from an exhaust port communicating with one of the one row of exhaust valves, so It is connected to an inlet of an air supply port communicating with one of the valves (Claim 5).

According to the method of the present invention, there is provided a control method for an engine with an EGR device provided with an EGR passage that extracts a part of exhaust gas and recirculates it to an intake port.
(1) The supply air is swirled by means for swirling the supply air in a fixed direction in the supply port and supplied to the combustion chamber of the engine.
(2) The supply air is distributed by centrifugal force generated by the rotation of the supply air in a portion closer to the outer periphery with respect to the cylinder central portion of the combustion chamber to hold a gas having a low EGR concentration.
(3) EGR gas is introduced into the central part of the combustion chamber to maintain the EGR concentration at the central part at a higher concentration than the part near the outer periphery.
(4) An air-fuel mixture having a non-uniform EGR concentration between the supply air and the EGR gas is formed in the combustion chamber.
(5) Spraying fuel in a non-uniform air-fuel mixture.
The engine with the EGR device is controlled by the five-stage operation (claim 1).

That is, according to the method of the present invention, known means such as providing blades in the air supply port to give the air turning force by the blades, or curving the air supply port to give the air turning force, etc. Thus, the supply air is swirled around the center of the cylinder and supplied to the combustion chamber of the engine.
In the combustion chamber, the fuel injected from the center of the combustion chamber becomes a premixed combustion state in the vicinity of the center of the combustion chamber, becomes a high temperature combustion state, and in the central portion and the outer portion of the central portion. It becomes a diffusion combustion state, and has a low oxygen concentration at the outer peripheral portion near the inner wall surface of the cylinder liner.
The combustion in which the combustion chamber is in a premixed combustion state in the central portion of the combustion chamber and is in a diffusion combustion state in the outer peripheral portion outside it becomes remarkable in the combustion of a large diesel engine whose cylinder bore diameter exceeds 150 mm.

In such a state in the combustion chamber, according to the present invention, low-temperature air having a high density gathers at the outer peripheral portion due to the centrifugal force generated by the swirling of the supply air in the supply port. The portion is made rich in the supply air to hold a gas with a low EGR concentration. As a result, the portion near the outer periphery of the combustion chamber is filled with the oxygen-rich gas with a low EGR concentration, and thus combustion is promoted and soot generation is avoided.
On the other hand, in the vicinity of the center of the combustion chamber of the combustion chamber, the temperature is high in the premixed combustion zone, and EGR gas from the EGR passage is introduced into this portion, and the EGR concentration in the central portion is set near the outer periphery. The concentration is kept higher than that, and the combustion is slowed down to suppress the high temperature. As a result, NOx is easily generated, and the EGR gas in the vicinity of the central part of the high-temperature combustion chamber is kept at a higher concentration than the part near the outer periphery, slowing the combustion and suppressing the temperature rise, thereby preventing the generation of NOx. To do.

As described above, an air-fuel mixture having a non-uniform EGR concentration is formed in the portion near the outer periphery of the combustion chamber, and the EGR gas-rich constitution is formed in the central portion of the combustion chamber. The fuel is sprayed into a simple mixture and burned.
Therefore, the portion near the outer periphery of the combustion chamber becomes oxygen rich and low EGR concentration combustion, and soot generation is avoided. In addition, the vicinity of the central portion of the combustion chamber is rich in EGR gas and the combustion becomes slow, so that the temperature rise is suppressed and the generation of NOx is avoided.

And according to the first device invention for carrying out the control method,
A swirl flow generating means for swirling the supply air in a fixed direction in the combustion chamber, and the supply air flow flows in layers in the supply port toward the combustion chamber of the engine, and the EGR gas passes through the EGR passage. Since it is connected to the air supply port so as to flow toward the combustion chamber in the same direction as the layered airflow and in a state of being partly separated without mixing with the layered airflow (Claim 2). ),
A portion of the supply air that flows in layers in the supply port toward the combustion chamber of the engine was separated without mixing EGR gas in the same direction as the layered supply airflow and with the layered supply airflow. By connecting to the supply port so as to flow toward the combustion chamber in a state, the EGR gas flows toward the combustion chamber in a state where it is partly separated without being mixed with the supply air.
That is, since the distance is short in the intake port, the EGR gas and the supply air are not mixed completely, and further flow in layers in the same direction as described above. Are separated into a layer and introduced into the combustion chamber.
As a result, a non-uniform air-fuel mixture in which EGR gas is layered with the supply air and introduced into the combustion chamber is introduced into the combustion chamber. Due to the non-uniform air-fuel mixture, the swirl flow given to the air supply causes the density to increase. The action of gathering large low-temperature air at the outer peripheral portion can be obtained more effectively.
Therefore, the portion near the outer periphery of the combustion chamber becomes oxygen rich and low EGR concentration combustion, soot generation is avoided, and the vicinity of the central portion of the combustion chamber is rich in EGR gas and the combustion becomes slow, and the temperature rises. It is suppressed and generation | occurrence | production of NOx can be avoided.

According to the second device invention for carrying out the control method,
The engine with the EGR device has a swirl flow generating means for swirling the supply air in a fixed direction in the combustion chamber, and the EGR passage opens into the intake port so that the EGR gas merges with the supply air flow. A throttle part having a smaller area than that of the other part is formed in the air port corresponding to the opening part, and is configured to promote the suction of EGR gas from the opening part by the venturi effect of the throttle part ( (Claim 3), and preferably, since the throttle part is formed in a projecting part projecting a part of the peripheral wall in the air supply port facing the opening (Claim 4), the projecting part is constituted by the projecting part. By restricting the area of the throttle portion to other portions in the air supply port, the vent portion of the throttle portion causes the EGR gas to merge with the air supply air from the opening that opens into the air supply port. Of EGR gas Since so as to facilitate entry, inhalation of EGR gas is promoted static pressure in the vicinity of the throttle portion becomes lower.
As a result, the increase in the flow rate of the supply air and the promotion of the intake of the EGR gas do not completely mix the supply air and the EGR gas within a short distance in the intake port, and the supply air and the EGR gas are not uniform. It will flow into the combustion chamber in a separate state. As a result, a non-uniform air-fuel mixture is introduced, and because of this non-uniform air-fuel mixture, the swirl flow imparted to the supply air can more effectively obtain the action of collecting low-temperature air having a high density at the outer periphery. It is done.
Therefore, EGR gas with increased EGR efficiency can be collected in the central portion of the combustion chamber, and generation of NOx can be avoided due to EGR gas rich in the vicinity of the central portion.
On the other hand, the portion near the outer periphery of the combustion chamber becomes rich in oxygen and has a low EGR concentration, so that combustion is promoted and soot generation is avoided.

In the present invention, it is preferable that two intake valves and two exhaust valves are provided side by side, and the EGR passage is led out from an exhaust port communicating with one of the exhaust valves in one row, so It may be connected to an inlet of an air supply port communicating with one of the valves (Claim 5). By supplying EGR gas from one of the exhaust valves in one row to only one of the intake valves in the other row, A strong swirl flow in the combustion chamber can be generated by the two air supply valves, and the supply of EGR gas from one air supply valve on one side causes a shift in the inflow of EGR gas in the combustion chamber. This improves the non-uniformity between the air supply and the EGR gas in the air and more effectively obtains the action of collecting low-temperature air having a high density due to the strong swirling flow at the outer peripheral portion.
Therefore, the portion near the outer periphery of the combustion chamber becomes oxygen rich and low EGR concentration combustion, soot generation is avoided, and the vicinity of the central portion of the combustion chamber is rich in EGR gas and the combustion becomes slow, and the temperature rises. It is suppressed and generation of NOx can be avoided.

Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.
(First embodiment)

  FIG. 1 is a cross-sectional view (a cross-sectional view taken along line BB in FIG. 2) showing a supply and exhaust configuration around a cylinder of a diesel engine with an EGR device according to a first embodiment of the present invention. FIG. 2 is an AA arrow view of FIG. FIG. 3 is an operation explanatory diagram of the supply air and EGR gas in the combustion chamber according to the first embodiment of the present invention. 4 is a view taken along the line DD in FIG.

  1 and FIG. 8 showing the prior art, in a diesel engine (hereinafter referred to as an engine) denoted by reference numeral 100, combustion is performed by fuel injection from a fuel injection valve 107 (see FIG. 2) mounted at the center of a cylinder head 111. The exhaust gas after being passed through the exhaust valve 104 and the exhaust port 109 provided in two in each cylinder and then sent to the exhaust turbine 120 of the exhaust turbocharger 122 (see FIG. 8). 120 is driven.

  On the other hand, the air compressed by the compressor 121 coaxially driven by the exhaust turbine 120 (see FIG. 8) passes through the air supply pipe 125, is cooled by the air cooler 134, passes through the throttle valve 123, and is supplied to the air supply port 108. Enters the combustion chamber 103 through the air supply port 108 and the air supply valve 105, burns down, and pushes down the piston 101 into which the piston ring 106 is inserted along the inner surface of the cylinder liner 102.

  The above configuration is the same as that of a conventionally known diesel engine with a two-valve EGR device. The present invention relates to a method for controlling an air supply device provided with an EGR device and the device.

  In FIG. 1, a part of the engine exhaust gas is extracted from the branch point 110 a of the exhaust port 109 to become EGR gas, and this EGR gas is joined to the intake port 108 through the EGR passage 110 provided in the cylinder head 111. (As in this example, the supply valve 105 and the exhaust valve 104 are two two-valve supply / exhaust valves, but the supply valve 105 and the exhaust valve 104 are one. explain).

According to the first embodiment of the present invention, first, in the air supply port 108, as shown in FIG. 3, the swirling flow 1a in which a constant swirling force is applied to the air supply is changed into an air supply port as shown in FIG. 108.
The swirling flow 1a is formed by a known method such as providing blades in the air supply port 108 to give the air turning force by the blades, or bending the air supply port to give the air turning force. By means, the supply air is swirled 1a.
The swirl flow 1a in the air supply port 108 forms a swirl flow 1 in the combustion chamber 103 (see FIG. 1) of the engine.

Here, in the combustion chamber 103, as shown in FIG. 4, the flame is hot in the premixed combustion zone at the central portion 107c in the vicinity of the central portion 100a of the combustion chamber 103. Also, the outer region is a diffusion combustion region, and the outer peripheral region 107b near the inner wall surface of the cylinder liner 102 has a low oxygen concentration.
In such a combustion state in the combustion chamber 103, according to the method of the present invention, the swirling of the air supply in the air supply port 108 is swirled by known means to form the swirling flow 1a ( 2) and is supplied to the combustion chamber 103 of the engine to form a swirling flow 1 (see FIG. 3).
Due to the centrifugal force generated by the swirl 1a, low-temperature air having a high density gathers at the outer peripheral portion, so that the supply air is distributed to the portion 107b near the outer periphery, and a gas with a low EGR concentration is held in the portion 107b near the outer periphery. Let me.
As a result, the portion 107b near the outer periphery of the combustion chamber 103 is filled with the oxygen-rich gas having a low EGR concentration, and thus generation of soot is avoided.

Further, on the other hand, as shown in FIG. 4, the central portion 107c in the vicinity of the center portion of the combustion chamber 103 is likely to become high temperature in the premixed combustion zone, and the EGR gas from the EGR passage 110 is introduced into this portion, By maintaining the EGR concentration in the central portion 107c at a higher concentration than that in the portion 107b near the outer periphery, the combustion is slowed and the temperature rise is suppressed.
As a result, the vicinity of the central portion 107c of the combustion chamber 103 where NOx is likely to be generated at a high temperature maintains the EGR gas at a higher concentration than the portion 107b near the outer periphery, slows the combustion and suppresses the high temperature, and reduces NOx. Prevent occurrence.

With this operation, an air-fuel mixture having a non-uniform EGR concentration between the supply air and the EGR gas is formed in the combustion chamber 103. Then, fuel spray 107a is performed in the non-uniform air-fuel mixture by the fuel injection valve 107 from the center of the engine (FIG. 3 shows the case where the fuel injection valve 107 has six injection holes).
(Second embodiment)

As a first means for carrying out the control method of the first embodiment, there is a means of the second embodiment shown in FIG. FIG. 5A is a partial cross-sectional view of the cylinder head according to the second embodiment, and FIG. 5B is a cross-sectional view taken along the line CC in FIG.
In the second embodiment, the inside of the air supply port 108 flows in a layered manner toward the combustion chamber 103 of the engine in the form of a supply airflow layer, and the EGR gas flows in the same direction as the layered supply airflow Wt. The air supply port 108 is connected to the air supply port 108 so as to flow toward the combustion chamber 103 so that the air supply air flow Wt flows without being mixed (EGR gas flow Wa).

Thereby, the EGR gas Wa flows toward the combustion chamber 103 in a state where the EGR gas Wa is not mixed with the supply air Wt and is partially separated.
That is, since the EGR gas Wa does not mix with the supply air Wt and flows in layers in the same direction as described above because the distance is short in the intake port 108, the EGR gas Wa is supplied. The gas Wt and a part of the gas Wt are separated and joined in a layered manner and introduced into the combustion chamber 103.
As a result, the non-uniform air-fuel mixture in which the EGR gas Wa is combined with the supply air Wt in a layered manner is introduced into the combustion chamber 103, and the swirl flow given to the air supply Wt due to the non-uniform air-fuel mixture. Thus, the action of collecting low-temperature air having a high density at the outer peripheral portion can be obtained more effectively. Then, fuel spray is performed in the non-uniform air-fuel mixture and burned.
Therefore, the portion 107b near the outer periphery of the combustion chamber 103 becomes rich in the supply air and burns at a low EGR concentration, so that generation of soot is avoided, and the vicinity of the central portion 107c of the combustion chamber 103 is rich in EGR gas and the combustion is slow. Therefore, high temperature is suppressed and generation of NOx can be avoided.
(Third embodiment)

As a second means for implementing the control method of the first embodiment, there is a means of the third embodiment shown in FIG. FIG. 6 is a partial sectional view of the cylinder head according to the third embodiment.
In the third embodiment, the EGR passage 110 is opened into the air supply port 108 so that the EGR gas merges with the air supply Wt.
That is, the opening portion on the supply port 108 side of the EGR passage 110 is directed so as to face the throttle portion 3 described later. Therefore, the opening portion 110s of the EGR passage 110 may be bent as shown in FIG.
The throttle portion 3 corresponds to the opening portion 110 s to form the throttle portion 3 with a smaller area than the other portions in the air supply port 108, and the opening portion 110 s is formed to form the throttle portion 3. A part of the peripheral wall in the air supply port 108 opposite to the air supply port 108 is formed on the protruding portion 2.

  According to the third embodiment, by restricting the area of the restricting portion 3 constituted by the protruding portion 2 as compared with other portions in the air supply port 108 (area L), the venturi effect of the restricting portion 3 is achieved. Thus, the intake of the EGR gas Wa from the opening 110s opened in the supply port 108 can be promoted so that the EGR gas Wa merges with the supply air Wt.

Therefore, by narrowing the area more than the other part in the air supply port 108, the static pressure in the vicinity of the throttle part is lowered by the venturi effect of the throttle part 3, so that the EGR gas Wa merges with the air supply Wt. Inhalation of the EGR gas Wa from the opening 110s that opens into the air supply port 108 is promoted.
As a result, due to the increase in the flow rate of the supply air and the promotion of the intake of the EGR gas Wa, the supply air Wt and the EGR gas Wa are not completely mixed within a short distance in the intake port 108, and the supply air Wt and EGR are not mixed. The gas flows into the combustion chamber 103 in a non-uniform separation state from the gas Wa. As a result, a non-uniform air-fuel mixture is introduced, and because of this non-uniform air-fuel mixture, the swirl flow imparted to the supply air can more effectively obtain the action of collecting low-temperature air having a high density at the outer periphery. It is done.
Therefore, EGR gas with increased EGR efficiency can be collected in the central portion of the combustion chamber 103. In the central portion, EGR gas is rich and combustion becomes slow, so that the temperature rise is suppressed and generation of NOx can be avoided.
On the other hand, the portion near the outer periphery of the combustion chamber 103 becomes rich in oxygen and combustion is promoted, so that generation of soot is avoided.
(Fourth embodiment)

FIG. 7 is a block diagram corresponding to FIG. 2 showing a fourth embodiment of the present invention.
In the fourth embodiment, a fuel injection valve 107 is provided at the center of the cylinder of the combustion chamber 103 of the engine, and two supply valves 105a and 105b and two exhaust valves 104a and 104b are arranged side by side. ing.
Then, the EGR passage 110 provided in the cylinder head 111 is led out from the exhaust port 109a communicating with one of the exhaust valves 104a in one row (branch point 110a), and is connected to one of the intake valves 105b in the other row. It connects with the confluence | merging part 110b of the supply port 108b which connects.
According to the fourth embodiment, since the EGR gas is supplied from one of the exhaust valves 104a in one row to only one of the intake valves 105b in the other row, the strong swirling flow in the combustion chamber is generated by the two supply valves. The supply of EGR gas from one air supply valve 105b on one side causes a shift in the inflow of EGR gas Wa in the combustion chamber 103, and the supply air and EGR gas in the combustion chamber 103 are The non-uniformity is improved, and the action of collecting low-temperature air having a high density due to the strong swirling flow at the outer peripheral portion can be obtained more effectively.
Note that an exhaust port 109b communicating with the exhaust valve 104b and an air supply port 108a communicating with the air supply valve 105a may be connected.

  According to the present invention, in a diesel engine with an EGR device, it is possible to provide a diesel engine that achieves complete combustion by reducing NOx by supplying EGR gas and preventing generation of soot in the combustion gas.

It is sectional drawing (BB sectional drawing of FIG. 2) which shows the supply and exhaust structure around the cylinder of the diesel engine with an EGR apparatus which concerns on 1st Example of this invention. It is an AA arrow line view of FIG. 1 concerning 1st Example of this invention. It is operation | movement explanatory drawing in the combustion chamber of the air supply and EGR gas which concern on 1st Example of this invention. FIG. 4 is a view taken along line DD of FIG. 3 according to the first embodiment of the present invention. (A) is a fragmentary sectional view of the cylinder head concerning the said 2nd Example, (B) is CC sectional drawing in (A). It is a fragmentary sectional view of the cylinder head concerning the 3rd example of the present invention. FIG. 9 is a diagram corresponding to FIG. 2 according to a fourth embodiment of the present invention. It is a block diagram which shows the whole structure of the conventional diesel engine with an EGR (exhaust gas recirculation) apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Swirling flow 2 Protrusion part 3 Restriction part 100 Engine (4-cycle diesel engine)
DESCRIPTION OF SYMBOLS 101 Piston 102 Cylinder liner 103 Combustion chamber 104,104a, 104b Exhaust valve 105,105a, 105b Supply valve 107 Fuel injection valve 108,108a, 108b Supply port 109,109a, 109b Exhaust port 110 EGR passage 110b Merging part 111 Cylinder Head 122 Exhaust turbocharger 123 Throttle valve

Claims (5)

In a control method of an engine with an EGR device comprising a fuel injection valve in the center of a cylinder of an engine, and an EGR passage that extracts a part of exhaust gas and recirculates it to an air supply port.
Centrifugal force generated by swirling of the air supply at a portion closer to the outer periphery with respect to the center of the cylinder of the combustion chamber by swirling the air supply by means for swirling the air supply in a certain direction and supplying it to the combustion chamber of the engine Distributes the supply air to hold a gas having a low EGR concentration, and injects EGR gas into the central portion of the combustion chamber to keep the EGR concentration at the central portion higher than that near the outer periphery. Thus, the control of the engine with the EGR device is characterized in that an air-fuel mixture having a non-uniform EGR concentration of the supply air and the EGR gas is formed in the combustion chamber, and fuel spray is performed in the non-uniform air-fuel mixture. Method. In an engine with an EGR device comprising a fuel injection valve in the center of the cylinder of the engine and an EGR passage that extracts a part of the exhaust gas and recirculates it to the supply port,
A swirl flow generating means for swirling the supply air in a fixed direction in the combustion chamber, and the supply air flow flows in layers in the supply port toward the combustion chamber of the engine, and the EGR gas passes through the EGR passage. The air supply port is connected to the air supply port so as to flow toward the combustion chamber in the same direction as the layered air supply air and in a state where the layered air supply air is partly separated without mixing with the layered air supply air. Engine with EGR device. In an engine with an EGR device comprising a fuel injection valve in the center of the cylinder of the engine and an EGR passage that extracts a part of the exhaust gas and recirculates it to the supply port,
A swirl flow generating means for swirling the supply air in a fixed direction in the combustion chamber; and opening the EGR passage into the supply port so that EGR gas merges with the supply air flow; A throttle part with a smaller area than the other part is formed corresponding to the opening part, and EGR gas suction from the opening part is promoted by the venturi effect of the throttle part. engine.   The engine with an EGR device according to claim 3, wherein the throttle portion is formed in a protruding portion that projects a part of a peripheral wall in the air supply port that faces the opening.   Two air supply valves and two exhaust valves are provided side by side, and the EGR passage is led out from an exhaust port communicating with one of the exhaust valves in the one row, and the air supply communicating with one of the air supply valves in the other row The engine with an EGR device according to claim 2, wherein the engine is connected to an inlet of a port.

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