JPS60198364A - Exhaust reflux device - Google Patents

Abstract

PURPOSE:To make improvements in engine performance and exhaust capacity, by installing a storage chamber storing a part of combustion gas at more than the specified pressure, a high pressure passage connecting this storage chamber to an engine cylinder chamber and a valve device opening or closing this high pressure passage in synchronization with a speed of engine revolution. CONSTITUTION:Suction air is taken into a cylinder chamber 22 from a suction port 24 via a suction valve 26 and burned after being ignited at a spark plug 28. And, when entering the latter half of an expansion stroke where combustion ends, an opening part 31 of a high pressure passage 30 is opened by a valve device 31 whereby a part of combustion gas flows into a storage chamber 29 from the high pressure passage 30. Afterward, it enters the expansion stroke, and when an exhaust valve 27 is opened, gas inside the cylinder chamber 22 is exhausted to an exhaust port 25. Successively, when again it enters the expansion stroke from a suction stroke, the said opening part 31 is opened again. Therefore, the gas inside the storage chamber 29 is led into the cylinder chamber 22 after the suction air is taken in. Accordingly, the combustion gas is able to flow back to the cylinder chamber 22 without entailing any drop in charging efficiency of the suction air.

Description

[Detailed description of the invention] (Technical field) The present invention relates to an exhaust gas recirculation device for an internal combustion engine.

(Prior technology) In order to suppress the generation of nitrogen oxides (NOx), which are harmful exhaust substances from internal combustion engines, an exhaust recirculation device (E
GR device) is known.

An example of this EGR device will be explained based on FIG. 1 (see Nissan Motor Co., Ltd.: r ECCSL Series Engine Technical Manual, June 1979). Exhaust passage 2 of internal combustion engine l
An exhaust gas recirculation passage 5 (EGR passage) is formed so as to communicate with the area downstream of the throttle valve 4 of the intake passage 3, and an exhaust gas recirculation passage 5 (EGR passage) is formed in the middle of the EGR passage 5 between and. A valve 6 (EGR valve) is installed.

Then, engine suction negative pressure regulated to an appropriate pressure by a negative pressure control solenoid valve 8 (VCM0M pulp) is introduced into the negative pressure chamber of the diaphragm device 7 of this EGR valve 6, and the EGR Valve 6 is opened and closed.

This VCM0M valve reduces engine suction negative pressure to a constant level in its constant pressure section, and further dilutes it with the atmosphere to a predetermined pressure in a solenoid section that opens and closes in response to pulse signals from the control device 9. Introduced into the EGR valve 6.

The control device 9 controls the solenoid based on signals from various operating state detection means such as a crank angle sensor 10, a throttle valve switch 11, an air flow meter 12, an ignition switch (not shown), and a water temperature sensor 14. The duty ratio of the pulse signal to the EGR valve 6 is determined, and the negative pressure applied to the EGR valve 6 is controlled so that an amount of exhaust gas recirculation is obtained according to the operating state of the engine.

Note that 15 is an idle control valve, 16 is an air regulator, 17 is a fuel injector, 18 is a canister, and 119 is a catalytic converter.

By the way, in such a conventional exhaust gas recirculation device,
The exhaust gas from the engine is guided into the intake passage 3, from where it is sucked into the engine cylinder chamber along with fresh air.
Intake air filling efficiency decreases.

Therefore, it is unavoidable that the engine output decreases due to exhaust gas recirculation, and for this reason, the current situation is to ensure high output by not performing exhaust gas recirculation when the engine is near full throttle.

However, on the other hand, NOx is more likely to be generated when the engine is at full throttle, and if it is possible to perform exhaust gas recirculation at times like these to reduce NOxk, it will be possible to significantly improve exhaust performance. .

(Object of the Invention) An object of the present invention is to provide an exhaust gas recirculation device that enables exhaust gas recirculation without reducing intake air filling efficiency and further improves engine performance and exhaust performance.

(Structure and operation of the invention) This invention includes a storage chamber in which a portion of the gas after combustion is stored at a predetermined pressure or higher, a high-pressure passage that connects this storage plan to an engine cylinder chamber, and a high-pressure passage that is synchronized with engine rotation. It consists of a valve means that opens and closes.

A part of the gas burned in the engine cylinder chamber is stored in a storage chamber while maintaining a certain combustion pressure, and this gas is supplied to the cylinder chamber through a high-pressure passage by a valve means that opens at least at the beginning of the compression stroke of the engine. .

Therefore, the gas after combustion is supplied to the cylinder chamber after a predetermined amount of fresh air has been drawn into the cylinder chamber, thereby making it possible to perform exhaust gas recirculation without reducing the intake air filling efficiency.

(Example) Fig. 2 shows a cross section of an internal combustion engine, 20 is a cylinder block, 21 is a cylinder head, 22 is a cylinder chamber, 23 is a piston, 24 and 25 are intake ports and exhaust ports, 26.27 are intake pulp and exhaust pulp, 48.4
9 is a rocker arm of pulp 26°27.

The intake air sucked into the cylinder chamber 22 via the intake pulp 26 is ignited by the spark plug 28 (in the case of a gasoline engine), and after being combusted, it is transferred from the exhaust pulp 27 to the cylinder chamber 22.
At this time, a storage chamber 29 having a predetermined volume is formed in the cylinder head 21 above the cylinder chamber 22 so as to store a part of the burned gas.

This storage chamber 29 is integrally formed inside the cylinder head 21 by, for example, casting, so as to withstand high pressure.
Separated from the surrounding area.

This storage chamber 29 is connected to the cylinder chamber 22 via a high pressure passage 30 penetrating the inner wall of the cylinder head 21, and an opening 31 of the high pressure passage 30 on the cylinder chamber 22 side
A valve means 32 is provided for opening and closing the high pressure passage 30.

This valve means 32 has a third valve for suction and exhaust pulp 26,27.
It is installed as a valve, and includes a poppet-shaped valve body 33 that opens and closes the opening 31, and a valve spring 35 that biases the valve body 33 in the closing direction via a stem portion 34 that passes through the cylinder head 21. , a rocker arm 36 that abuts the tip of the stem portion 34, and a rocker arm 36? It consists of a cam 37 that opens and closes the valve body 33 via Il.

This cam 37 is the cam shaft 38 of the suction and exhaust pulp 26.27
The formation field is 1 rotation for every 2 rotations of enref.

The profile of the cam 37 is formed such that the opening portion 31 is opened at the beginning of the compression stroke and at the latter half of the expansion stroke as the cam 370 rotates.

Specifically, the cam profile is formed so that the opening 31 is opened for a short period of time immediately after the intake stroke ends and the intake pulp 26 closes, and immediately before the exhaust pulp 27 opens in the latter half of the expansion stroke.

In such a configuration, the intake air (mixture of fuel and fresh air) taken into the cylinder chamber 22 from the intake port 24 via the intake valve 26 is ignited by the spark plug 28 near compression top dead center, and is rapidly ignited. However, in the second half of the expansion stroke when this combustion ends, the opening 31 of the high pressure passage 30 is opened by the valve means 32 as shown in FIG. 3C).

Therefore, a part of the gas burned in the cylinder chamber 22 flows into the storage chamber 29 from the high pressure passage 30, and gas at a predetermined pressure is stored in the storage chamber 29 as shown in FIG. 3(a).

Thereafter, when the exhaust stroke begins, the exhaust pulp 27 opens as shown in FIG. 3(b), and the gas in the cylinder chamber 22 is discharged to the exhaust port 25.

Then, when the intake stroke starts from this state, the intake valve 26 is opened and intake air is drawn from the intake port 24 into the cylinder chamber.
However, at the same time as the intake stroke ends and the compression stroke begins, the opening 31 of the high pressure passage 30 is opened again by the valve means 32.

For this reason, the gas at a predetermined pressure in the storage chamber 29 is guided into the cylinder chamber 22 after the intake air is drawn into the cylinder chamber 22. At this time, since the pressure in the cylinder chamber 22 is low (near atmospheric pressure), the gas at a predetermined pressure is The gas in the storage chamber 29 flows forcefully into the cylinder chamber 22. This allows the gas after combustion to be transferred to the cylinder chamber 2 without reducing the intake air filling efficiency.
2 can be refluxed. Note that FIG. 3(d) shows changes in the amount of gas in the storage chamber 29.

Therefore, even when the engine is fully opened, exhaust gas recirculation is possible without impairing engine performance, and NOxk can be sufficiently reduced while ensuring high engine output. Furthermore, exhaust gas recirculation lowers the combustion temperature and avoids concerns about knocking.

Since exhaust gas is introduced after the intake air is filled, even if the combustion temperature decreases, the pressure inside the cylinder chamber 22 (1f; i internal pressure) remains high as shown in Figure 3 (al). Rather, the maximum torque is improved.

On the other hand, there is also the advantage that the gas flowing forcefully from the storage chamber 29 improves the flow state within the cylinder chamber 22 and ensures good combustibility.

Further, when the engine is fully opened, the air-fuel ratio is normally set to the rich side, but this allows the air-fuel ratio to be set to the stoichiometric air-fuel ratio, and therefore not only NOx but also CO, etc. can be sufficiently reduced.

By the way, the volume of the storage chamber 29 is 10 of the cylinder volume.
When the EGR rate is set in the range shown in FIG. 4, the EGR rate within this range is effective in reducing NOx and preventing knocking.

This EGR rate is determined by the engine's compression ratio, intake and exhaust pulp.
．． Although the required value changes depending on the opening characteristics of the engine 27, for example, it is possible to increase the compression ratio of the engine by increasing the size of the storage chamber 29 and significantly lowering the EGR rate.

In addition, since knocking is prevented in the ignition timing, the ignition timing can be set near the best fuel efficiency point as shown in FIG. 5, and the fuel qk can be sufficiently improved.

In addition, in this embodiment, due to the design of the cam 37, the pressure passage 3
Although it is difficult to open 0 for a short period of time, the suction and exhaust pulp 2
Even if the timing overlaps with the valve opening timing on June 27, it will have little effect. Although the capacity of the storage chamber 29 is fixed, it may be made variable so that the EGR rate can be switched and controlled according to the operating conditions. In addition, the EGR rate can also be changed by controlling the opening/closing timing of the valve means 32 and the valve lifter.

FIG. 6 shows another embodiment of the present invention, in which a storage chamber 39 is provided so as to be connected to an exhaust passage 40 near the exhaust port 25, and part of the combustion gas discharged from the cylinder chamber 22 to the exhaust passage 40 is provided. The parts are guided to a storage chamber 39. Preservation room 3
A check valve (reed valve) 41 is installed on the inlet side of the cylinder chamber 9, and uses the pulsation of gas discharged from the cylinder chamber 22 to store gas at a predetermined pressure or higher in the storage chamber 39.

The storage chamber 39 is connected to the cylinder chamber 22 via a high pressure passage 42, and a valve means 43 opens and closes the opening 31 of the storage chamber 39.
are provided in substantially the same manner as in FIG.

In this case, the profile of the cam 44 is formed to open the opening 31 for a short period of time at the beginning of the compression stroke, that is, immediately after the intake stroke has ended and the intake pulp 26 has closed.

On the other hand, a diaphragm type flow control valve 45 is provided on the exit side of the storage chamber 39 to control the amount of gas flowing back from the storage chamber 39 to the cylinder chamber 22 .

The flow rate control valve 45 is operated by negative pressure from a negative pressure source, and is provided with a negative pressure control valve 47 that regulates this negative pressure in accordance with a signal from a control circuit 46.

The control circuit 46 receives an engine load signal, a rotational speed signal, etc. from a sensor (not shown), etc., and controls the opening degree of the flow rate control valve 45 according to the operating conditions.

Accordingly, exhaust gas recirculation can be performed in the same manner as in the embodiment described above, and the EGR rate can be variably controlled according to the operating conditions, so that appropriate exhaust gas recirculation can be performed at all times.

Note that each embodiment may be used in combination with a conventional device.

(Effects of the Invention) Since exhaust gas recirculation can be performed accurately without reducing intake air filling efficiency even when the engine is fully opened, there is an effect that exhaust performance can be significantly improved while ensuring high engine performance.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the configuration of a conventional device, Fig. 2 is a sectional view showing an embodiment of the present invention, Figs. Figures 5 and 5 are graphs showing examples of setting the ignition timing, and Figures 6 to 6 are cross-sectional views showing other embodiments of the present invention. 21... Cylinder head, 22... Cylinder chamber, 2
6...Intake/Gulp, 27...Exhaust pulp, 29.
...Storage chamber, 30...High pressure passage, 31...Opening,
32... Valve means, 33... Valve body, 37... Cam,
39... Storage chamber, 40... Exhaust passage, 41... Check valve, 42... High pressure passage, 43... Valve means, 4
4...Cam, 45...Flow rate control valve, 46...Control circuit.

Claims (1)

[Claims] 1. A storage chamber for storing part of the gas after combustion at a predetermined pressure or higher, and a high-pressure passage connecting this storage chamber to an engine cylinder chamber;
An exhaust gas recirculation system for an internal combustion engine, which comprises a valve means that opens and closes this high-pressure passage in synchronization with engine rotation. 2. The exhaust gas recirculation system for an internal combustion engine according to claim 1, wherein the valve means is configured to open at the beginning of the engine's compression stroke and at the latter half of the engine's expansion stroke.