WO2006129840A1

WO2006129840A1 - Diesel engine and method of controlling the same

Info

Publication number: WO2006129840A1
Application number: PCT/JP2006/311177
Authority: WO
Inventors: Kunio Hasegawa; Hajime Fujita; Katsumasa Kurachi; Koji Matsubara
Original assignee: Daihatsu Motor Co., Ltd.
Priority date: 2005-05-31
Filing date: 2006-05-30
Publication date: 2006-12-07
Also published as: JP2006336466A

Abstract

A diesel engine having an external EGR device (15) and an internal EGR device (18), the external EGR device (15) circulating exhaust gas from the inside of a combustion chamber into the combustion chamber, the internal EGR device (18) increasing residual exhaust gas remaining in the combustion chamber. The amount of inert gas in the combustion chamber is increased to a level greater than that at which the amount of production of soot is at the peak, and this is performed by both the external EGR device (15) and the internal EGR device (18).

Description

TECHNICAL FIELD The present invention relates to a diesel engine such as a two-cycle or four-cycle engine and a control method thereof. BACKGROUND ART Generally, in a diesel engine, in order to suppress the generation of NO X, an exhaust path from a combustion chamber and an intake path to the combustion chamber are connected via an exhaust gas recirculation path to discharge from the combustion chamber. A part of the exhaust gas is recirculated into the combustion chamber through the exhaust gas recirculation passage. This is called an external EGR (Exhaust Gas Recirculation) device. In this external EGR device, the amount of exhaust gas recirculated into the combustion chamber, that is, the EGR rate (the sum of the exhaust gas recirculation amount and the intake air amount into the combustion chamber divided by the exhaust gas recirculation amount) The higher the temperature, the lower the combustion temperature in the combustion chamber, so that NO X generation can be suppressed. In this case, conventionally, when the EGR rate was increased, it was considered that the amount of soot, that is, the smoke, suddenly increased when the external EGR rate exceeded a certain limit. On the other hand, Patent Document 1 as a prior art, as shown by curves A and B in FIG. 1, shows that if the EGR rate to the combustion chamber by the external EGR device is larger than the maximum allowable limit of smoke. Focusing on the fact that there is a peak in the amount of smoke generated and the amount of smoke generated, and there is a phenomenon that smoke decreases rapidly when the external EGR rate is further increased beyond this peak. When the amount of inert gas in the combustion chamber is increased, the amount of soot generated gradually increases and reaches a peak. In diesel engines, the amount of soot generated in the combustion chamber is less than the amount of inert gas at which soot generation peaks. By increasing the amount of active gas, the temperature of the fuel and the surrounding gas during combustion in the combustion chamber is suppressed to a temperature lower than the temperature at which soot is generated, and soot is generated in the combustion chamber. It has proposed an internal combustion engine which is adapted to prevent the that. However, in Fig. 1, curve A shows the case where the exhaust gas from the external EGR device is forcibly cooled to about 90 with a large cooler, and curve B shows the exhaust gas from the external EGR device forcibly cooled. This is the case. Patent Document 1: Japanese Patent Application Laid-Open No. 11-36 9 2 3 And this prior art (Patent Document 1) is that when the temperature of the fuel and the surrounding gas in the combustion chamber is lower than a certain temperature, By stopping the growth of hydrocarbons in the middle before reaching soot, soot is no longer generated, and when the temperature is so low, the amount of NO x generated is very small. It is based on the principle. In this case, in the prior art (Patent Document 1), the state in which the amount of soot and N0 X generated can be reduced is considered only once from the combustion chamber, regardless of the exhaust gas remaining in the combustion chamber. A part of the exhaust gas discharged is returned to the combustion chamber again by the external EGR device. However, in order to realize a state where the amount of soot and NOX generated in the combustion chamber can be reduced, a large amount of exhaust gas must be recirculated into the combustion chamber by the external EGR device. The exhaust gas recirculated from the external EGR device to the combustion chamber is rapidly reduced in temperature when it is once exhausted from the combustion chamber, and its activity is low. As a result, the ignition and combustion of the fuel in the combustion chamber is significantly hindered, which increases the risk of misfire. DISCLOSURE OF THE INVENTION The present invention is that the exhaust gas remaining in the combustion chamber without being exhausted from the combustion chamber after being combusted in the combustion chamber is high in temperature and contains a radical component and has high activity. Paying attention to this technical problem, it is important to use this residual exhaust gas to reliably eliminate the problems of the prior art, that is, the occurrence of misfire when the amount of inert gas in the combustion chamber is increased. To do. In order to achieve this technical problem, claim 1 of the present invention comprises: a combustion chamber for burning fuel; an intake passage that communicates with the combustion chamber and supplies gas to the combustion chamber An exhaust gas recirculation passage communicating with the combustion chamber, and an external EGR device for recirculating at least part of the exhaust gas exhausted from the combustion chamber to the combustion chamber via the exhaust gas recirculation passage; An internal EGR device that increases residual exhaust gas remaining in the combustion chamber after burning the fuel in the chamber; and a low-temperature combustion region in which the amount of inert gas in the combustion chamber is increased and the amount of soot generated exceeds a peak The control device includes an exhaust gas recirculated to the combustion chamber and a control device that adjusts the amount of residual exhaust gas by controlling the external EGR device and the internal EGR device. A second aspect of the present invention is the diesel engine according to the first aspect, wherein the control device determines a ratio of residual exhaust gas to exhaust gas recirculated into the combustion chamber by the external EGR device. It is characterized by controlling to 1/8. Claim 3 of the present invention is the diesel engine according to claim 1 or 2, wherein the control device includes at least an idling operation in an entire operation range of the diesel engine. The internal EGR is controlled to increase the residual exhaust gas in the combustion chamber. According to a fourth aspect of the present invention, in the diesel engine according to any one of the first to third aspects, the control device is configured to reduce the amount of exhaust gas recirculated to the combustion chamber in a region before reaching the low temperature combustion region. The external EGR device is controlled so that the amount of the inert gas corresponding to the amount of the inert gas in the low temperature combustion region increases at a stroke. According to a fifth aspect of the present invention, in the diesel engine according to any one of the first to third aspects, the diesel engine is a two-cycle diesel engine provided with a scavenging compressor, and the internal EGR device includes the scavenging gas. The feature is that the scavenging pressure for the scavenging port by the compressor is reduced. A sixth aspect of the present invention is the diesel engine according to any one of the first to fifth aspects, further comprising an EGR cooler in the exhaust gas recirculation passage. Claim 7 of the present invention is the diesel engine according to any one of claims 1 to 4 and 6, wherein the diesel engine is a four-cycle diesel engine, and the four-cycle diesel engine is provided in the combustion chamber. It is characterized by having first exhaust valve control means for controlling the timing of closing the exhaust valve so that the exhaust gas remains in the combustion chamber. Claim 8 of the present invention is the diesel engine according to any one of claims 1 to 4 and 6, wherein the diesel engine is a four-cycle diesel engine, and the four-cycle diesel engine is provided in the combustion chamber. A second exhaust valve control means is provided for controlling the timing of closing the exhaust valve so that the exhaust gas discharged from the exhaust port is sucked back into the combustion chamber upon intake. A ninth aspect of the present invention provides the diesel engine according to any one of the first to fourth and sixth aspects, wherein the four-cycle diesel engine is configured to exhaust the exhaust gas discharged from the intake port from the intake valve of the combustion chamber. Suction again into the combustion chamber during intake It is characterized by having an intake valve control means for controlling the opening time to return. Claim 10 of the present invention is the diesel engine according to any one of claims 7 to 9, wherein at least one of the first exhaust valve control means, the second exhaust valve control means, and the intake valve control means. Both are characterized by the inclusion of two. Claim 11 of the present invention comprises: a combustion chamber that burns fuel; an intake passage that communicates with the combustion chamber and supplies gas to the combustion chamber; an exhaust gas recirculation passage that communicates with the combustion chamber; An external EGR device having an exhaust gas return passage for returning at least a portion of the exhaust gas exhausted from the chamber to the combustion chamber via the exhaust gas return passage; and after the fuel is burned in the combustion chamber, A diesel engine control method comprising an internal EGR device for increasing residual exhaust gas remaining in a combustion chamber, wherein the amount of inert gas in the combustion chamber is increased by the external EGR device, and the amount of soot generated peaks The amount of exhaust gas recirculated to the combustion chamber and the amount of residual exhaust gas is adjusted by controlling the external EGR device and the internal EGR device in a low temperature combustion region exceeding There. The effects of the present invention are as follows.

The above-mentioned prior art has a low-temperature combustion state in which the amount of inert gas in the combustion chamber is larger than the amount of inert gas at which the amount of soot peaks, regardless of the exhaust gas remaining in the combustion chamber. By achieving the exhaust gas recirculated into the combustion chamber exclusively by the external EGR device, the amount of exhaust gas produced by the external EGR device is gradually increased by the amount of soot generated. The amount of exhaust gas recirculated into the combustion chamber by the external EGR device must be significantly increased until the peak is reached. In contrast, according to the present invention, as described in claims 1 and 11, the amount of inert gas before the amount of soot reaches a peak due to an increase in the amount of inert gas. The external EGR device secures the exhaust gas recirculated into the combustion chamber while the amount of inert gas in the case where the amount of soot generation is larger than the peak amount of inert gas. In this way, it is ensured by both the exhaust gas recirculated into the combustion chamber at the internal combustion chamber and the residual exhaust gas increased by the internal EGR device, so that it is recirculated into the combustion chamber by the external EGR device. The amount of exhaust gas can be reduced by the amount of residual exhaust gas increased by the internal EGR device. The residual exhaust gas remaining in the combustion chamber without being discharged from the combustion chamber has a higher temperature and contains more radical components than the exhaust gas recirculated to the combustion chamber by the external EGR device. Due to its high activity, the ignition and combustion of the fuel can be greatly accelerated by increasing the residual exhaust gas volume with the internal EGR device. Therefore, according to the present invention, in a diesel engine, in order to suppress the generation of soot and NO x to a small amount, the amount of inert gas in the combustion chamber is larger than the amount of inert gas at which the generation amount of soot reaches a peak. If this happens, the risk of misfire can be reliably reduced. In addition, by reducing the risk of misfire, the amount of exhaust gas and residual exhaust gas recirculated to the combustion chamber can be increased by this amount, so that the generation of soot and NOX can be further suppressed, and the exhaust gas A high level of cleanliness can be achieved. In this case, as described in claim 2, the ratio of the residual exhaust gas increasing in the internal EGR device to the exhaust gas recirculating into the combustion chamber in the external EGR device is 1/16 to 1 Z8. It is preferable to configure the settings. If it is less than 1 16, the amount of residual exhaust gas that increases in the internal EGR device is small, so that the ignition and combustion promotion of fuel by the exhaust gas remaining in the combustion chamber can be effectively achieved. In addition, when the value exceeds 1 Z 8, the amount of residual exhaust gas that increases in the internal EGR device increases, so the combustion temperature in the combustion chamber becomes too high and soot generation increases. It will be. By the way, in a recent diesel engine, the combustion is performed at a lean leaner than the stoichiometric air-fuel ratio in the entire operation region, so that the low load including at least idling operation in the entire operation region is achieved. · The temperature of the exhaust gas in the low-speed operation region is lower than the other operation regions due to excess air for lean combustion, and as a result, a catalytic exhaust gas purification device installed in the exhaust path Because the temperature in the chamber does not rise, there is a problem that the exhaust gas purification efficiency is low. This problem, that is, that the purification efficiency of the catalytic exhaust gas purification device is low in the low-load / low-rotation operation region including idling operation, is that the exhaust gas is exhausted into the combustion chamber by the external EGR device as in the previous technology. This can be improved by reducing the amount of excess air that is inhaled by increasing the amount of exhaust gas recirculation, but on the other hand, the ignition / combustibility of the fuel becomes unstable. Therefore, as described in claim 3, when the amount of the soot generated is larger than the amount of the inert gas at which the soot generation peak, the amount of the inert gas that is recirculated into the combustion chamber by the external EGR device and It is configured to ensure that both the exhaust gas increased by the internal EGR device and the residual exhaust gas increase in the low-load / low-rotation operation region including at least idling operation in the entire operation region of the diesel engine. As a result, the ignition and combustibility of the fuel can be reliably promoted in a state where the generation of soot in the low load / low rotation operation region including the idling operation is reliably suppressed. If a catalyst-type exhaust gas purification device is installed in the exhaust path, the temperature of the exhaust gas purification device can be increased. The cleaner can be achieved. Next, as described in claim 4, when the amount of exhaust gas recirculated to the combustion chamber by the external EGR device and the amount of inert gas in the combustion chamber are increased, the amount of soot generated gradually increases. In the period before reaching the peak, the amount of soot generated increases to the amount of the inert gas when the amount of the generated inert gas is larger than the peak amount of the inert gas. In the process of gradually increasing the amount of exhaust gas recirculated to the combustion chamber by an external EGR device, the amount of soot generated reaches its peak. In other words, it is possible to reliably avoid reaching a state where it reaches a state where it is reached, in other words, to maintain a lower value than before when the amount of generated soot reaches its peak. As a result, the amount of inert gas until the amount of soot reaches a peak due to the increase in the amount of inert gas is secured from the state in which the exhaust gas recirculated into the combustion chamber is secured by the external EGR device. When the amount of soot generated is larger than the amount of inert gas that makes a peak, the amount of inert gas is increased by the exhaust gas recirculated into the combustion chamber by the external EGR device and the internal EGR device. In the transitional period when shifting to a state secured by both the residual exhaust gas and the remaining exhaust gas, it is possible to avoid the occurrence of a large amount of soot and to smoothly carry out the transition. In particular, when the exhaust gas recirculated into the combustion chamber is increased by the external EGR device, the combustion state can be prevented from becoming unstable. Next, according to the present invention, as described in claim 5, the diesel engine is a two-cycle diesel engine provided with a scavenging compressor, and the internal EGR device is provided in the scavenging compressor. It is proposed that the scavenging pressure be lowered. As described above, the residual exhaust gas that should remain in the combustion chamber during the combustion of fuel is the exhaust gas from the previous combustion. In the case of a two-cycle diesel engine, the previous combustion leads to the next combustion. The time until is about half that of a four-cycle diesel engine. In the meantime, the activity of the residual exhaust gas can be reduced to a small extent due to the decrease of the radical component in the residual exhaust gas. In other words, in the case of a two-cycle diesel engine, exhaust gas having a higher activity than in the case of a four-cycle diesel engine can remain in the combustion chamber, so that the above-described effects can be reliably achieved. . In addition, the increase in residual exhaust gas remaining in the combustion chamber can be accurately and reliably controlled by lowering the scavenging pressure in the scavenging compressor. Next, according to the present invention, as described in claim 6, by providing the exhaust gas recirculation passage with the EGR cooler, the exhaust gas is cooled, and the amount of soot generated can be reduced. Next, as described in claims 7 to 10 of the present invention, in a four-cycle diesel engine, the timing for closing the exhaust valve of the combustion chamber so as to leave the exhaust gas in the combustion chamber is controlled. One exhaust valve control means, second exhaust valve control means for controlling the timing of closing the exhaust valve of the combustion chamber so that the exhaust gas discharged from the exhaust port is sucked back into the combustion chamber upon intake. A four-cycle diesel engine by having at least one intake valve control means for controlling the timing of opening the intake valve of the chamber so that the exhaust gas discharged from the intake port is sucked back into the combustion chamber upon intake. In this case, low temperature combustion and radical addition are possible. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the relationship between the amount of soot generated and the external EGR rate in an internal combustion engine.

FIG. 2 is an overall view showing an embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described with reference to FIG. In this figure, reference numeral 1 denotes a diesel engine having at least two cylinders, and the diesel engine 1 includes a scavenging compressor 2 that is driven to rotate by the diesel engine 1. By supplying air compressed by a scavenging compressor to a scavenging port (not shown) in each cylinder, scavenging in each cylinder is performed. This scavenging compressor may be provided in an air intake passage 8 from an air cleaner 7 to be described later, as shown by a two-dot chain line in FIG. Reference numeral 3 denotes an exhaust turbocharger that is formed by directly connecting an exhaust turbine 3 a and a blower compressor 3 b. The exhaust turbocharger 3 has an diesel exhaust bin 3 a at the inlet of the diesel turbocharger 3 a. An exhaust passage 4 from an exhaust manifold 1a in the engine 1 is connected to an exhaust passage 5 to the atmosphere at an outlet of the exhaust turbine 3a, and a catalyst is placed in the middle of the exhaust passage 5 to the atmosphere. An exhaust gas purification device 6 of the type is provided. On the other hand, the air intake passage 8 from the air cleaner 7 is on the suction side of the blower compressor 3 b of the exhaust turbocharger 3, and the air intake passage 9 to the scavenging compressor 2 is on the discharge side. Are connected to each other, and a throttle valve 10 for controlling the intake air is provided in the middle of the air intake passage 8, and an in-cooler 11 is provided in the middle of the intake passage 9. . The exhaust passage 5 to the atmosphere and the intake passage 9 are connected via an exhaust gas recirculation passage 12 that guides a part of the exhaust gas in the exhaust passage δ to the intake passage 9. An exhaust gas recirculation control valve 1 3 and an EGR cooler 14 are provided in the middle of the exhaust gas recirculation passage 1 2. When the opening of the exhaust gas recirculation control valve 1 3 is increased, the exhaust gas to the intake passage 9 is exhausted. When the return flow of the gas increases and the opening of the exhaust gas recirculation control valve 13 decreases, the recirculation amount of the exhaust gas to the intake passage 9 is reduced. In other words, the exhaust gas recirculation passage 12, the exhaust gas recirculation control valve 13 and the EGR cooler 14 constitute an external EGR device 15. On the other hand, the intake passage 9 is provided with a bypass passage 16 connecting the upstream side and the downstream side of the scavenging compressor 2, and a bypass flow control valve 17 is provided in the middle of the bypass passage 16. When the bypass flow rate control valve 17 is opened, a part of the air is compressed by the scavenging compressor 2 and returned to the suction side of the scavenging compressor 2, so that the scavenging The scavenging air pressure is reduced to a certain level, and the scavenging air pressure is further reduced when the opening of the bypass flow control valve 17 is further increased. In other words, these bypass passage 16 and bypass flow control valve 17 constitute an internal Ε GR device 18. Reference numeral 19 designates the exhaust gas recirculation control valve 13 and the bypass by using signals from the opening sensor 20 and the rotation sensor 21 and the like in the diesel engine 1 as inputs. It is a controller for opening and closing the flow control valve 17 as described below. That is, the controller 19 is configured to perform exhaust gas recirculation in the external EGR device 15 in all other operating areas of the diesel engine 1 except for the low load / low speed operating area including idling operation. The control valve 13 is opened, and a part of the exhaust gas in the exhaust passage 5 is recirculated to the intake passage 9 via the exhaust gas recirculation passage 12 and eventually into the combustion chamber in each cylinder. As a result, as described in the above-mentioned prior art, at least the other operation areas except the low load / low rotation operation area including the idling operation in the entire operation area of the diesel engine 1 A configuration in which the amount of inert gas until the amount of generated gas reaches a peak due to an increase in the amount of inert gas is controlled by the external EGR device 15 so as to be secured by the exhaust gas recirculated into the combustion chamber. I have to. In addition to this, the controller 19 reduces a part of the exhaust gas in the exhaust passage 5 in the low load / low rotation operation region including at least the idling operation out of the entire operation region in the diesel engine 1. In addition to returning to the combustion chamber in each cylinder by the external EGR device 15, the opening force of the bypass flow rate control valve 17 in the internal EGR device 18 is increased, and the scavenging compressor Part of the air compressed in step 2 By bypassing back to the intake side, the scavenging air pressure for the scavenging port in each cylinder is lowered, and this scavenging air pressure is lowered, thereby reducing the scavenging efficiency in each cylinder and remaining in the combustion chamber. The amount of exhaust gas is larger than the amount of residual exhaust gas in the case of a normal diesel engine. As a result, in the low-load / low-rotation operation region including idling operation, as described in the prior art, the inert gas in the case where the amount of soot generation is larger than the inert gas amount that peaks. The amount is controlled so as to be secured by both the exhaust gas recirculated into the combustion chamber by the external EGR device 15 and the residual exhaust gas increasing by the internal EGR device 18. . In other words, in the low-load / low-rotation operation region including at least the idling operation in the entire operation region of the diesel engine 1, the inert gas in the case where the amount of soot generation is larger than the peak inactive gas amount. The amount is ensured by both the exhaust gas recirculated into the combustion chamber by the external EGR device 15 and the residual exhaust gas that increases by the internal EGR device 18. The amount of exhaust gas returned to the combustion chamber by the device 15 can be reduced by the amount of residual exhaust gas increased by the internal EGR device 18. The residual exhaust gas remaining in the combustion chamber without being discharged from the combustion chamber is higher in temperature than the exhaust gas recirculated to the combustion chamber by the external EGR device 15 and contains a radical component. Because it contains a large amount and is rich in activity, it is possible to promote the ignition and combustion of fuel by increasing the amount of residual exhaust gas with the internal EGR device 18. In the case of the two-cycle diesel engine 1, the time from the previous combustion to the next combustion is as short as about half that of the four-cycle diesel engine. Can be minimized by the reduction of radical components in the residual exhaust gas. In other words, exhaust gas having higher activity than that of a four-cycle diesel engine remains. Therefore, the above-mentioned effects can be achieved, and further acceleration of fuel ignition / combustion can be achieved. In this case, when the controller 19 operates the external EGR device 15 and the internal EGR device 18 simultaneously in a low load / low rotation operation region including idling operation, The ratio of the residual exhaust gas that increases in the internal EGR device 1 8 to the exhaust gas recirculated into the combustion chamber in the EGR device 15 is regulated to 1 Z 16 to 1/8. As a result, it is possible to achieve ignition and combustion promotion of the fuel by the exhaust gas remaining in the combustion chamber without increasing the generation of soot. Furthermore, the controller 19 increases the amount of exhaust gas recirculated to the combustion chamber by the external EGR device 15, and the amount of soot generated gradually increases as the amount of inert gas in the combustion chamber increases. For example, when the amount of the above-mentioned generation is greater than the peak amount of inert gas at the time point A 1 on the upper right in curve A in Fig. 1, The active gas amount is configured to increase all at once, for example, to the amount of inert gas at point A 2 on the lower right side of curve A in Fig. 1. As a result, in the process of gradually increasing the amount of exhaust gas recirculated to the combustion chamber by the external EGR device 15, the amount of soot is increased to a state where the amount of soot reaches a peak. Can be avoided reliably. In addition, at point A 2 in Fig. 1, the exhaust gas is increased by the internal EGR device 18, so there is no instability of combustion due to excessive increase of inert gas. Although the above embodiment is applied to a two-cycle diesel engine 1, the present invention is not limited to this, and can be similarly applied to a four-cycle diesel engine. However, in the case of a four-cycle diesel engine, the internal EGR device for increasing the residual exhaust gas remaining in the combustion chamber includes

(i). Means to increase the residual exhaust gas in the combustion chamber more than in the case of a normal diesel engine by making the timing of closing the exhaust valve early until the exhaust gas remains in the combustion chamber. (First exhaust valve control means). (ii). By delaying the timing of closing the exhaust valve until the exhaust gas discharged from the exhaust port is sucked back into the combustion chamber during intake, the residual exhaust gas in the combustion chamber Means to increase more (second exhaust valve control means).

(iii). By opening the intake valve early so that the exhaust gas discharged from the intake port is sucked back into the combustion chamber during intake, the remaining exhaust gas in the combustion chamber is reduced to that of a normal diesel engine. Means that increase more than the case (intake valve control means). (iv). Means for combining two or more of (i), (ii) and (iii) above.

Etc. exist. The controller 19 can also serve as the first exhaust valve control means, the second exhaust valve control means, and the intake valve control means. If the two-cycle diesel engine is a Uniflow type equipped with an exhaust valve at the top of the combustion chamber, instead of decreasing the scavenging pressure as described above, or at the same time, the exhaust valve It is possible to increase the residual exhaust gas remaining in the combustion chamber by making the closing time earlier. Industrial applicability

The diesel engine of the present invention can reliably eliminate the occurrence of misfire when the amount of inert gas in the combustion chamber is increased.

Claims

The scope of the claims

1. a combustion chamber for burning fuel;

An intake passage that communicates with the combustion chamber and supplies gas to the combustion chamber; an exhaust gas recirculation passage that communicates with the combustion chamber; and at least a portion of the exhaust gas exhausted from the combustion chamber passes through the exhaust gas recirculation passage An external EGR device for returning to the combustion chamber via

An internal EGR device for increasing residual exhaust gas remaining in the combustion chamber after burning the fuel in the combustion chamber;

By controlling the external EGR device and the internal EGR device in a low-temperature combustion region where the amount of inert gas in the combustion chamber is increased and the amount of soot generated exceeds the peak, exhaust gas recirculated to the combustion chamber and , Diesel engine equipped with a control device that adjusts the amount of residual exhaust gas.

2. The control device according to claim 1, wherein the ratio of the residual exhaust gas to the exhaust gas recirculated into the combustion chamber by the external EGR device is controlled to be 1 16 to 18. The diesel engine described in 1.

3. The control device controls the internal EGR so as to increase the residual exhaust gas in the combustion chamber in a low load and low rotation operation region including at least an idling operation in the entire operation region of the diesel engine. The diesel engine according to claim 1 or 2, characterized by the above.

4. The control device is configured to reduce the amount of exhaust gas recirculated to the combustion chamber to the amount of inert gas corresponding to the amount of inert gas in the low temperature combustion region in the region before reaching the low temperature combustion region. Said external E to increase The diesel engine according to any one of claims 1 to 3, wherein the diesel engine is controlled.

5. The diesel engine is a two-cycle diesel engine equipped with a scavenging compressor, and the internal EGR device is configured to reduce the scavenging air pressure to the scavenging port of the scavenging compressor. The diesel engine according to any one of claims 1 to 4, wherein the diesel engine is characterized.

6. The diesel engine according to any one of claims 1 to 5, further comprising an EGR cooler in the exhaust gas recirculation passage.

7. The diesel engine is a four-cycle diesel engine, wherein the four-cycle diesel engine controls the timing of closing the exhaust valve of the combustion chamber so that the exhaust gas remains in the combustion chamber. The diesel engine according to any one of claims 1 to 4 and 6, further comprising valve control means.

8. The diesel engine is a four-cycle diesel engine, and the four-cycle diesel engine causes the exhaust valve of the combustion chamber to suck the exhaust gas exhausted from the exhaust port back into the combustion chamber again during intake. The diesel engine according to any one of claims 1 to 4, further comprising second exhaust valve control means for controlling the closing timing.

9. The diesel engine is a four-cycle diesel engine, and the four-cycle diesel engine uses the intake valve of the combustion chamber so that the exhaust gas discharged from the intake port is sucked back into the combustion chamber during intake. When to open The diesel engine according to any one of claims 1 to 4, further comprising an intake valve control means for controlling the engine.

10. The diesel engine according to any one of claims 7 to 9, comprising at least two of the first exhaust valve control means, the second exhaust valve control means, and the intake valve control means.

1 1. Combustion chamber for burning fuel,

An exhaust passage that communicates with the combustion chamber and supplies gas to the combustion chamber; and an exhaust gas recirculation passage that communicates with the combustion chamber; and at least part of the exhaust gas exhausted from the combustion chamber An external EGR device having an exhaust gas recirculation passage for recirculation to the combustion chamber through the passage;

A control method for a diesel engine comprising an internal EGR device for increasing residual exhaust gas remaining in the combustion chamber after burning the fuel in the combustion chamber,

The amount of inert gas in the combustion chamber is increased by the external EGR device;

Controlling the external EGR device and the internal EGR device in the low-temperature combustion region where the amount of soot generated exceeds the peak adjusts the amount of exhaust gas recirculated to the combustion chamber and the amount of residual exhaust gas The method for controlling the diesel engine.