JPH05202811A - Exhaust gas recirculating device for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Objective] The exhaust gas recirculation device (EGR) secures sufficient EGR gas to be sent to the cylinder in the intake stroke, suppresses temperature drop with a simple configuration, and stabilizes combustion. An EG that directly connects each exhaust port 6 in the exhaust process and each of the cylinders # 1 to # 4 in the intake process with a flow path 15 and opens / closes each flow path 15 in the intake process.
R gas intake valve 16 is arranged in each cylinder # 1 to # 4,
Also, the flow path 15 is connected to the control unit 18.
A flow rate adjusting valve 17 for adjusting the flow rate of the EGR gas flowing through is provided on the flow path 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation device (hereinafter referred to as an "EGR device") for sending exhaust gas discharged from a cylinder into the cylinder during an engine intake process, and more specifically, to direct the exhaust gas directly to the cylinder. It relates to EGR introduced into the inside.

[0002]

2. Description of the Related Art In a conventional EGR system, a part of exhaust gas discharged from an exhaust port is recirculated to an intake manifold or an intake port as EGR gas, and a negative pressure in an intake pipe is required for introduction into a cylinder. It's being used. Therefore, when the engine negative pressure in the pipe becomes small in the medium and high load regions,
We couldn't use enough exhaust gas. In particular,
In a lean burn engine, that is, a lean burn engine, the theoretical air-fuel ratio is high and the amount of air in the air-fuel mixture increases, so that the three-way catalyst cannot remove Nox. Therefore, it is necessary to apply EGR or the like, but this type of engine cannot secure sufficient exhaust gas because the internal pressure of the intake pipe is high.
Further, when a large amount of exhaust gas was introduced (the EGR rate was large) during lean operation, that is, during lean burn operation, combustion became unstable.

[0003]

Therefore, as countermeasures against these problems, the temperature of the exhaust gas used for EGR is raised, and combustion is improved by the generation of swirl (lateral vortex) flow and tumble (longitudinal vortex) flow at the time of inhaling the air-fuel mixture. However, in order to implement these, there is a problem that a device for heating exhaust gas is provided separately from the EGR device, or the structure of the EGR device itself becomes complicated.

[0004]

Therefore, according to the present invention, a part of the exhaust gas discharged from the exhaust valve during the exhaust process is EG
An exhaust gas recirculation device that feeds R gas as R gas into the cylinder during the intake stroke of the engine, and a flow path that directly guides the EGR gas to the cylinder, and EGR gas that is located in the cylinder and that opens and closes the flow path during the intake stroke. The intake valve is composed of a suction valve, a flow rate adjusting valve that is provided on the flow path and adjusts the EGR gas flow rate flowing through the flow path, and a control unit that controls the flow rate adjusting valve.

[0005]

The EGR gas, which has been conventionally guided to the intake port side, is directly introduced into the cylinder during the intake stroke.
The temperature drop of the gas can be suppressed, and the EGR is performed by utilizing the pressure difference in the pipe during the exhaust process and the intake process.
Gas can be efficiently introduced into the cylinder of the intake process.

[0006]

EXAMPLES Examples of the present invention will be described below. In FIG. 1, reference numeral 1 indicates an intake manifold, into which air is sucked through an air cleaner 2, an accelerator valve 3, and a surge tank 4. The sucked air is supplied to each of the intake ports 5 arranged in the cylinders # 1 to # 4.
Is sucked into the cylinder in the intake process of each cylinder, and is exhausted from the exhaust port 6 as exhaust gas through the exhaust manifold 7 and the catalytic converter 8 in the exhaust process.
A three-way catalyst is used in the catalytic converter 8 to remove NOx and the like from the exhaust gas discharged.

As shown in FIG. 2, each of the cylinders # 1 to # 4 has a pentroof type combustion chamber 9 so that the inflowing air becomes a tumble (longitudinal vortex) flow therein, and the cylinders of the intake port 5 have the same structure. The cross-sectional shape is formed into an inverted triangle. The intake port 5 and the exhaust port 6 have an intake valve 10 and an exhaust valve 11 which are opened and closed by a cam (not shown) during the intake process and the exhaust process.
Are provided respectively.

A fuel injection nozzle 12 is arranged on one side 5a of the intake port 5, and a spark plug 13 is arranged near the intake port 5a where the nozzle 12 is provided. That is, the spark plug 13 is provided on the side of the cylinder where the rich air-fuel mixture is generated, and the combustion time is shortened by igniting the air-fuel mixture. Further, the fuel injection nozzle 12 is controlled in fuel injection amount so that the theoretical air-fuel ratio becomes high until the engine speed and the engine load reach their predetermined values. That is, the concentration of the air-fuel mixture is lean.

On the other hand, on the exhaust port 6 side, the exhaust gas after combustion is recirculated back to the cylinders # 1 to # 4.
R14 is provided. The EGR 14 is a passage pipe 15 that introduces a part of the exhaust gas in the exhaust port 6 as EGR gas into the cylinder, and E that opens and closes the passage pipe 15 during the intake stroke.
The GR gas intake valve 16, a flow rate adjusting valve 17 for adjusting the EGR gas flow rate flowing in the flow path pipe 15, and a control unit 18 for controlling the flow rate adjusting valve 17 are included.

The flow passage pipe 15 is formed by forming a flow passage 15a which communicates with the exhaust port 6 and a flow passage 15b which communicates with the combustion chamber 9 as one pipe, and is divided by a flow rate adjusting valve 17. There is.

The EGR gas intake valve 16 is arranged in the combustion chamber 9 opposite to the intake side so as to join with the tumble flow at the time of intake, and promotes the tumble flow. The valve 16 can be opened / closed in synchronization with the opening / closing period of the intake valve 10. Here, intake and exhaust valves 10, 11
The opening / closing timing of the cylinders # 1 to # 4 of the EGR gas intake valve 16 will be described with reference to FIG. According to this figure, when the # 1 cylinder is inhaled, the # 3 cylinder is exhausted, and when the # 1 cylinder is inhaled, the # 4 cylinder is exhausted. Further, when the # 4 cylinder is intake, the # 2 cylinder is exhaust, and when the # 2 cylinder is intake, the # 1 cylinder is exhaust, and the intake valves 10 of the cylinders # 1 to # 4.
The EGR gas intake valve 16 is also at the maximum opening at the maximum opening of.

The flow rate adjusting valve 17 includes an upper chamber 17a and a lower chamber 17
A valve 17d is attached to a diaphragm 17c that separates it from b. The upper chamber 17a communicates with the manifold near the throttle valve 3 through the passage A, and the lower chamber 17 communicates with the surge tank 4 through the passage B.
d is biased in the direction of closing the flow path 15a by the internal pressure of the passage A and the coil spring 17e provided in the upper chamber 17a. Further, the passage A and the passage B are communicated with each other through the passage C, and the passage C has a solenoid valve 19 for adjusting the pressure between the passages A and B.
Is provided.

The solenoid valve 19 is connected to the control unit 18, and the opening degree of the valve is adjusted by an operation signal from the control unit 18. Various sensors such as an air-fuel ratio sensor (not shown) are connected to the control unit 18, calculate information from these sensors, and when the air-fuel ratio leans toward the lean side or when the engine load is low, medium load range, etc. Occasionally, an operation signal is issued according to these values, and the solenoid valve 19 is set to the maximum opening in the medium load range. That is, the flow control valve 17 is opened a lot so that a large amount of EGR gas flows.

With such a configuration, for example, when the intake valve 10 of the # 1 cylinder is in the open state (intake process), # 3 is used.
Since the exhaust valve 11 of the cylinder is in the open state (exhaust process) (see FIG. 3), a part of the exhaust gas with high exhaust pressure exhausted from the # 3 cylinder is guided into the flow path 15a. At this time, E
Since the GR gas intake valve 16 is open within the opening range of the intake valve 10, the EGR gas from the # 3 cylinder having a high pipe pressure can be directly sucked into the # 1 cylinder having a low pipe pressure in the intake stroke, The temperature drop of EGR gas can be suppressed more than the conventional type in which EGR gas is made to flow into the cylinder from the intake port side. If the air-fuel ratio is lean and the engine is operating (during lean operation), and the engine is operating under low load, the solenoid valve 19 does not open much and the flow rate adjusting valve 17 does not open.
Becomes a throttled state, the amount of EGR gas flowing from the flow passage 15a to the flow passage 15b decreases, and E fed into the cylinder E
The amount of GR gas, that is, the EGR rate can be suppressed.
Further, since the EGR gas suction valve 16 is arranged for strengthening the tumble flow, when the EGR gas is sucked, the tumble flow is strengthened and combustion efficiency is improved.

In this embodiment, the flow rate adjusting valve 1
The differential pressure on the intake side is used for opening and closing 7, but the invention is not limited to this. For example, a valve configured to be opened and closed by a stepping motor is provided between the flow paths 15a and 15b to drive the stepping motor. The EGR amount can also be controlled by the EGR gas flow rate adjusting structure in which the control unit 18 controls the above.

Next, FIG. 4 shows a second embodiment. Components having the same functions as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the second embodiment, the flow path 15 in the first embodiment is made shorter and abbreviated. That is, according to the valve timing shown in FIG. 3, the exhaust port of the cylinder in the exhaust process and the cylinder in the intake process are connected by one flow pipe 15 ', and the opening and closing of the flow pipe 15' is performed by the EGR valve. The suction valve 16 is used, and the EGR gas flow rate adjusting valve 17 'is provided on the flow path pipe 15'. The flow rate adjusting valve 17 'is a solenoid valve and has the same structure as the solenoid valve 19 shown in FIG.

As described above, the cylinder during the intake process and the exhaust port during the exhaust process are independently provided as a single flow pipe 1.
Since it was directly connected at 5 ', (for example, # 3 cylinder and # 4
Cylinder exhaust port 6) The pipe length can be made shorter than in the first embodiment, the structure of the EGR 14 can be simplified, and the differential pressure in the pipe can be used more directly.

[0018]

According to the present invention, the temperature drop of EGR gas can be suppressed with a simple structure, and sufficient EGR gas can be introduced, so that the combustion can be stabilized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an internal combustion engine in which a first embodiment of the present invention is implemented.

FIG. 2 is a schematic side view showing the configuration of the present invention.

FIG. 3 is a diagram showing opening and closing timings of intake and exhaust valves and an EGR intake valve.

FIG. 4 is a configuration diagram showing a second embodiment of the present invention.

[Explanation of symbols]

 14 Exhaust Gas Recirculation Device (EGR Device) 15, 15 'Flow Path 16 EGR Gas Intake Valve 17, 17' Flow Control Valve 18 Control Unit # 1 to # 4 Cylinder

Claims (1)

[Claims] 1. An exhaust gas recirculation device for feeding a part of exhaust gas discharged during an exhaust stroke into an inside of a cylinder during an intake stroke of an engine as an EGR gas, wherein the EGR gas from the cylinder during the exhaust stroke is exhausted during the intake stroke. A flow path directly leading to a certain cylinder, an EGR gas intake valve located in the cylinder for opening and closing the flow path during the intake process, and a flow rate adjusting valve provided on the flow path for adjusting the EGR gas flow rate flowing through the flow path. And an exhaust gas recirculation device for an internal combustion engine, which comprises a control unit for controlling the flow rate adjusting valve.