JPH0667846U - Exhaust gas recirculation control device for diesel engine - Google Patents

Abstract

(57) [Abstract] [Purpose] The objective is to reduce NOx by EGR and to improve the combustibility by increasing the intake utilization rate. [Structure] Directional port 17 that opens along the cylinder wall and spiral port 18 that opens near the fuel injection valve in the center of cylinder 5 are provided.
Is provided with a first intake manifold 3A communicating with the spiral port 18, a second intake manifold 3B communicating with the spiral port 18, an intake throttle valve 8 is provided at the inlet of the second intake manifold 3B, and an EGR control valve 16 is interposed between the EGR The passage 15 communicates with the second intake manifold 3B. As a result, the EGR gas is concentrated near the center of the cylinder where the intake utilization rate is low, and the intake utilization rate is increased.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an exhaust gas recirculation control device for a diesel engine.

[0002]

[Prior art]

 Conventionally, an exhaust gas recirculation (hereinafter referred to as EGR) device that recirculates a part of exhaust gas to the intake system has been known as one of the measures for reducing NOx emitted from a diesel engine (for example, actual opening 63-). No. 126549, etc.). Such an EGR device is provided with an EGR passage that connects the exhaust system and the intake system of the engine, and an EGR control valve is provided in the EGR passage to drive and control the EGR control valve in a predetermined operating region of the engine. However, a part of the exhaust gas is recirculated from the exhaust system to the intake system and supplied again into the cylinder. As a result, the combustion temperature is lowered and the NOx emission amount is reduced.

[0003]

[Problems to be solved by the device]

 However, in the conventional EGR device of this type, in order to suppress variations in combustion between cylinders, exhaust gas is recirculated to the intake system, uniformly mixed with intake air, and then supplied to the inside of the cylinder. However, there is a problem in that the combustibility is deteriorated because the amount of oxygen becomes small and the emission amount of smoke, particulates (exhaust particulates), HC, CO, etc. is increased and the output and fuel consumption are deteriorated.

The present invention has been made in view of the above circumstances. NOx can be reduced by introducing fresh air and EGR gas into the cylinder through separate paths to improve intake utilization efficiency, and output, It is an object of the present invention to provide an exhaust gas recirculation control device for a diesel engine that can prevent deterioration of fuel consumption and the like. Examples of internal combustion engines with two intake valves include those disclosed in Japanese Utility Model Publication No. 59-84220, Japanese Utility Model Publication No. 62-144, Japanese Utility Model Publication No. 62-3935, and the like.

[0005]

[Means for Solving the Problems]

 For this reason, in the exhaust gas recirculation control device for a diesel engine of the present invention, the fuel injection valve is arranged substantially in the center of the cylinder, while the directional port that opens in the tangential direction of the cylinder wall to generate a swirl along the cylinder wall. , A spiral port that opens near the fuel injection valve and creates swirl near the center of the cylinder is provided, while a first intake manifold that communicates with the directional port that is provided for each cylinder, and also for each cylinder A second intake manifold communicating with the spiral port is provided, and an intake throttle valve is provided at an inlet portion of the second intake manifold, and a part of exhaust gas in the exhaust passage is taken in by the second intake manifold. An exhaust gas recirculation passage is provided downstream of the throttle valve with an exhaust gas recirculation control valve interposed therebetween.

[0006]

[Action]

 In such a configuration, the tip of the fuel spray around the cylinder wall contains a lot of fresh air, and ignition is good, so that the ignition delay can be shortened. In addition, since the EGR concentrates in the center of the combustion chamber where the intake rate has been low, the fresh air utilization rate can be increased compared to the conventional case. Furthermore, when the fuel spreads, the swirl promotes mixing with the EGR, and an excessive rise in the combustion temperature can be suppressed. Therefore, NOx can be reduced and combustibility is improved, engine output and fuel consumption can be improved, and smoke and the like can be reduced.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall construction of a 4-cylinder diesel engine to which an embodiment of the EGR control device of the present invention is applied. In FIG. 1, an intake manifold 3 and an exhaust manifold 4 are attached to a cylinder head 2 of an engine body 1, respectively. The intake manifold 3 includes a first intake manifold 3A connected to a later-described directional port 17 provided for each cylinder 5, and a second intake manifold 3A similarly connected to a later-described spiral port 18 provided for each cylinder 4. It is branched to the manifold 3B. An intake pipe 7 having an air cleaner 6 and the like connected thereto is connected to a manifold inlet portion where both intake manifolds 3A and 3B join to introduce intake air. An intake throttle valve 8 is provided at the inlet of the second intake manifold 3B. Reference numeral 9 denotes an actuator that drives the intake throttle valve 8.

On the other hand, the exhaust manifold 4 is connected to an exhaust pipe 13 having an exhaust shutter 10, a particulate trap 11, an exhaust muffler 12 and the like. Reference numeral 14 denotes an actuator that drives the exhaust shutter 10. An EGR passage 15 is provided that connects the collector portion of the exhaust manifold 4 to the collector portion of the second intake manifold 3B downstream of the intake throttle valve 8 and circulates a part of the exhaust gas to the second intake manifold 3B side. The EGR passage 15 is provided with an EGR control valve 16 for controlling the exhaust gas recirculation amount.

In the cylinder head 2, two intake ports, that is, the above-described directional port 17 and spiral port 18 and one exhaust port 19 are formed for each cylinder 5, and the first intake manifold 3A and the second intake port 3A are respectively formed. It is connected to the intake manifold 3B and the exhaust manifold 4. Then, as shown in FIGS. 2 and 3, the directional port 17 opens in the tangential direction of the cylinder wall 5a of the cylinder 5 formed in the cylinder block 20 to generate a large swirl along the cylinder wall 5a. Therefore, the spiral port 18 opens near the fuel injection valve 21 mounted on the cylinder head portion near the approximate center of the cylinder 5 and swirls the intake air in the port to inject the fuel injection valve 2 in the cylinder 5. It creates a small swirl near 1. The intake valves 22 and 23 are provided at the openings of both ports 17 and 18, respectively. Reference numeral 24 denotes an exhaust valve. Further, in FIG. 3, reference numeral 25 denotes a cavity formed on the top surface of the piston 26.

Next, the operation will be described. In the operating region where the engine starts and performs EGR, the intake throttle valve 8 at the inlet of the second intake manifold 3B is closed, and the opening degree of the EGR control valve is controlled according to the operating state, so that the operating state is set. An appropriate EGR amount is introduced from the exhaust manifold 4 into the second intake manifold 3B via the EGR passage 15. On the other hand, since the intake throttle valve 8 is closed, the whole amount of the fresh air sucked from the intake pipe 7 is introduced to the first intake manifold 3A side. Then, it flows into the cylinder 5 from the directional port 17 along the cylinder wall 5a to generate a large swirl along the cylinder wall 5a. Further, the EGR gas flowing from the second intake manifold 3B into the spiral port 18 flows into the vicinity of the fuel injection valve 21 at the center of the cylinder 5 and produces a small swirl near the center of the cylinder 5. That is, in the cylinder 5, as shown in FIGS. 4 and 5, a large amount of fresh air 31 is present on the peripheral wall of the cavity 25, and the EGR gas 32 is concentrated in the central portion of the cavity 25.

Therefore, compared to the conventional engine with an EGR function, the ratio of the fresh air existing in the center of the cylinder, which has a low intake utilization rate with respect to the fresh air flowing into the cylinder 5, is small, and the intake utilization rate is reduced. Can be increased. Further, since a large amount of fresh air is present at the tip portion (near the cavity wall) of the spray 30 (shown in FIGS. 4 and 5) from the fuel injection valve 21, good ignition occurs and the ignition delay can be shortened. Further, since the mixture with the EGR gas is well performed during the combustion spread, it is possible to suppress the excessive increase of the combustion temperature.

As described above, NOx can be reduced, the combustibility can be improved to prevent the deterioration of the engine output and the fuel consumption, and the emission of exhaust harmful components such as smoke and particulates can be reduced. When EGR is not performed, the intake throttle valve 8 is opened and intake air is supplied from both the directional port 17 and the spiral port 18.

[0013]

[Effect of device]

 As described above, according to the present invention, two intake ports, a differential port and a spiral port, are provided, fresh air is supplied to the cylinder peripheral wall from the direction port, and EGR gas is supplied from the spiral port to the center of the cylinder. Since it is configured to supply air intensively in the vicinity, it is possible to increase the intake utilization rate, perform good ignition, prevent the deterioration of engine output, fuel consumption, etc., and suppress the emission of smoke, particulates, etc. it can. Also, it can be mixed well with the EGR gas while burning and spreading in the cylinder, the excessive rise of the combustion temperature can be suppressed, and NOx can be reduced.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a 4-cylinder diesel engine to which an embodiment of the present invention is applied.

FIG. 2 is a horizontal sectional view of a cylinder head portion of the above embodiment.

FIG. 3 is a vertical sectional view of a cylinder portion of the above embodiment.

FIG. 4 is a plan view of a cavity according to the above embodiment.

FIG. 5 is a vertical sectional view of a cavity according to the above embodiment.

[Explanation of symbols]

 1 Engine Main Body 2 Cylinder Head 3A First Intake Manifold 3B Second Intake Manifold 5 Cylinder 5a Cylinder Wall 8 Intake Throttle Valve 15 EGR Passage 16 EGR Control Valve 17 Directional Port 18 Spiral Port 21 Fuel Injection Valve 30 Fuel Spray 31 Fresh Air 32 EGR gas

Claims (1)

[Scope of utility model registration request] 1. A fuel injection valve is disposed substantially at the center of a cylinder, a directional port that opens in the tangential direction of the cylinder wall to generate swirl along the cylinder wall, and a cylinder that opens near the fuel injection valve. A first intake manifold communicating with the directional port provided for each cylinder and a second intake manifold communicating with the spiral port similarly provided for each cylinder while providing a spiral port for generating a swirl near the center. And an intake throttle valve provided at the inlet of the second intake manifold, and an exhaust gas recirculation control valve for returning a part of the exhaust gas in the exhaust passage to the downstream side of the intake throttle valve of the second intake manifold. An exhaust gas recirculation control device for a diesel engine, characterized in that the mounted exhaust gas recirculation passage is provided.