JPS6020575B2 - Exhaust gas recirculation device for multi-cylinder internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas recirculation device for a multi-cylinder internal combustion engine.

A method of recirculating exhaust gas is known as an effective method for reducing the harmful component NQ in exhaust gas.

However, exhaust gas recirculation (hereinafter referred to as EGR)
If the amount is increased, the propagation speed of the flame becomes slower, which not only slows down the combustion speed and makes it impossible to obtain stable combustion, but also reduces the ignitability and may cause a misfire in some cases. A method of increasing the combustion rate when exhaust gas is recirculated is to arrange and configure the combustion chamber, intake valve, piston, or intake pipe so as to generate a swirling flow or squish flow within the combustion chamber to increase the combustion rate. The method is known. However, an internal combustion engine employing this type of method has the disadvantage that it must be equipped with both an EGR device and a swirl flow or squish flow generation mechanism. In order to eliminate these drawbacks, a multi-cylinder internal combustion engine has been proposed in which ECR gas is directly injected into the combustion chamber and the ejected EGR gas causes turbulence within the combustion chamber. In this multi-cylinder internal combustion engine, a plurality of EGR gas supply branch passages that respectively communicate with each cylinder are connected to one EGR gas supply common passage, and sub-intake valves are arranged in each of the branch passages. The auxiliary intake valves of the cylinders are simultaneously opened when one cylinder is in the exhaust stroke and the other cylinder is in the intake stroke to inject exhaust gas into the other cylinder, thereby causing turbulence in the combustion chamber. It is composed of However, since the turbulence generated during the intake stroke is considerably attenuated at the end of the exhaust stroke, it is difficult to generate turbulence that continues during the combustion process. The present invention generates strong turbulence in the combustion chamber that continues during the combustion process using the exhaust gas ejected at the end of the compression stroke, increasing the combustion speed, thereby achieving a sufficient N○x reduction effect without causing torque fluctuations or misfires. An object of the present invention is to provide an exhaust gas recirculation device for a multi-cylinder internal combustion engine, which provides the following.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a plan view of a four-cylinder internal combustion engine according to the present invention.

In Figure 1, 1 is the engine body, 2 is the intake manifold, and 3 is the engine body.
is the exhaust manifold, 4a, 4b, 4c, 4d are each 1
The number cylinder, the second cylinder, the third cylinder, and the fourth cylinder are shown. Each cylinder 4a, 4b, 4c, 4d has an intake valve 5a, 5b, 5c, respectively.
, 5d and exhaust valves 6a, 6b, 6c, and 6d.
Each of these cylinders 4a, 4b, 4c, 4d is connected to each intake valve 5a, 5b, 5c, 5d and each intake boat 7a, 7b.
, 7c, 7d to the intake manifold 2, and on the other hand to the exhaust manifold 3 via the respective exhaust valves 6a, 6b, 6c, 6d and exhaust boats 8a, 8b, 8c, 8d. FIG. 3 shows a side sectional view of the No. 1 cylinder 4a of FIG. 1. The other cylinders 4b, 4c, and 4d are not particularly illustrated because they have the same structure as the first cylinder 4a. Third
Referring to the figure, the engine body 1 includes a cylinder block 10 and a cylinder bore 1 formed in the cylinder block 10.
The combustion chamber of the first cylinder 4a is provided between the top surface 12a of the piston and the inner wall 14a of the cylinder head. 15 is formed. A valve retainer 16 is fixed to the upper end of the valve stem of the intake valve 5a, and a valve spring 17 is inserted between the valve retainer 16 and the cylinder head 14. The intake valve 5a is actuated by a rocker arm 18', which in turn is driven by a camshaft 19 connected to the engine crankshaft (not shown) and rotating at a rotational speed of 1'2 of the crankshaft. An ECR supply branch passage 20a is formed in the cylinder head 14, and an auxiliary intake valve 21a is slidably provided in the cylinder head 14 to control the opening and closing of the combustion chamber side open end of this EGR supply branch passage 20a. It will be done.

A valve retainer 22 is fixed to the upper end of the valve stem of the sub-intake valve 21a, and a valve spring 23 is inserted between the valve retainer 22 and the cylinder head 14. This sub-intake valve 21a is driven by the camshaft 19 via the rocker arm 24. Further, as shown in FIG. 4, all electrodes 25 are arranged within the combustion chamber 15 during ignition. 1st
As shown in the drawings and FIG. 3, a hollow container 27 is fixed on the outer wall of the cylinder head 14, and this hollow container 27 has a storage chamber 28 therein. As shown in FIG. 3, the ECR gas supply branch passage 20a is connected to this storage chamber 28, and as shown in FIG. connected to. In addition, in FIG. 1, the auxiliary intake valves of the second cylinder 4b, the third aromatic cylinder 4c, and the fourth cylinder 4d are respectively 21b, 21c,
21d. FIG. 5 shows the opening timings of the intake valve, exhaust valve, and sub-intake valve of each cylinder.

In FIG. 5, the vertical axis shows the valve height, and the machine axis shows the crank angle. Also, in FIG. 5, curves A, B, C, and D indicate the exhaust valves 6a, 6b, 6 of each cylinder 4a, 4b, 4c, and
Curves B, F, G, and H' indicate the opening timings of the intake valves 5a, 5b, 5c, and 5d of each cylinder. Further, curves 1 and J indicate the opening timing of the sub-intake valve 21a of the first cylinder 4b, and curves K and L indicate the opening timing of the sub-intake valve 21a of the second cylinder 4b.
1b, curves M and N show the valve timings of the auxiliary intake valve 21c of the third cylinder 4c, and curves ◯ and P show the valve timings of the auxiliary intake valve 21d of the fourth cylinder 4d. Note that FIG. 5 shows the case where the ignition order is 1-2-3-4. Further, in FIG. 5, the compression stroke of each cylinder is indicated by an arrow. As is clear from FIG. 5, the auxiliary intake valve of each cylinder opens twice during one cycle.

For example, if we focus on the No. 1 cylinder, the auxiliary intake valve opens approximately in the middle of the exhaust stroke, as shown by curve A, 1, and then opens again at the end of the compression stroke, as shown by curve J. I know how to speak. The valve timing of the auxiliary intake valve is the same in other cylinders as well. When a certain cylinder is in the exhaust stroke, the auxiliary intake valve of that cylinder opens.

As described above, the sub-intake valve opens approximately in the middle of the exhaust stroke, but the exhaust gas pressure in the cylinder at this time is quite high. Therefore, the high-pressure exhaust gas is sent into the storage chamber 28 through the EGR supply branch passage, and as a result, the high-pressure exhaust gas is stored in the storage chamber 28. Next, when a certain cylinder reaches the end of its compression stroke, the sub-intake valve opens as described above. At the end of the compression stroke, the pressure inside the cylinder is quite high, but the pressure of the exhaust gas stored in the storage chamber 28 is much higher, so when the sub-intake valve opens, the exhaust gas flows into the storage chamber. 28 into the combustion chamber-15 at high speed via the EOR supply branch passage 20a and the sub-intake valve 21a,
Strong turbulence is given to the combustible mixture in the combustion chamber 15. In this way, strong turbulence is generated in the combustion chamber 15 at the end of the compression stroke, and this turbulence is relayed during the combustion process, thereby increasing the combustion speed while ensuring the N○x reduction effect of EGR gas. Expedited. Further, since the exhaust gas EE in the storage chamber 28 is kept substantially constant, the flow rate and flow velocity of the exhaust gas ejected to each cylinder are equal to each other. Accordingly,
Since the combustion speed in each cylinder does not vary, torque fluctuations are prevented from occurring. 6 to 8 show other embodiments of the embodiment shown in FIG. 3.

In addition, in FIGS. 6 to 8, the same components as in FIG. 3 are indicated by the same reference numerals. Referring to FIG. 6, on the cylinder head inner wall 14a there is a horizontal wall 30 and a pair of vertical walls 31.
, 32 and a semi-cylindrical wall 33.
is formed, and the valve portion of the sub-intake valve 21a is exposed within this spring 34. The semi-cylindrical wall 33 is arranged close to the periphery of the valve part of the sub-intake valve 21a, so that when the sub-intake valve 21a opens, the exhaust gas flows between the valve part and the valve formed on the left side in FIG. It is ejected into the combustion chamber 15 through the opening □ between the seats 35.
Further, as shown in FIG. 7, the groove 34 is formed to extend in the peripheral direction of the combustion chamber 15, and is therefore connected to the combustion chamber 15 from the EGR supply branch passage 20a through the auxiliary intake valve 21a.
The exhaust gas ejected into the combustion chamber 15 generates a strong swirling flow as shown by arrow Z in FIG. Since this swirling flow is continued during the combustion process, the combustion speed is greatly increased, and the N○x generated by the EGR gas is thereby
It is possible to obtain stable combustion while ensuring a reduction effect. In the embodiment shown in FIG. 6, the electrode 2 of the spark plug 26
5 is preferably arranged at the top of the combustion chamber 15. 9th
The figure shows a further embodiment of FIG.

In FIG. 9, the same components as in FIG. 3 are designated by the same reference numerals. Referring to FIG. 9, a recess 36 is formed in the cylinder head 14, into which an eight-chamber element 37 is press-fitted. A sub-combustion chamber 38 and a tendon passage 39 are formed within the sub-chamber element 37, and the electrode 25 of the spark plug 26 is disposed within the lotus passage 39. In this embodiment, a lean air-fuel mixture is introduced into the main combustion chamber 40 via the intake valve 5a during the intake stroke. Then, during the compression stroke, this lean mixture flows through the lotus passage 39.
is pushed into the auxiliary combustion chamber 38 through the auxiliary combustion chamber 38. At the end of the compression stroke, exhaust gas flows into the main combustion chamber 40 via the auxiliary intake valve 21a.
At this time, strong turbulence occurs within the main combustion chamber 40 due to the emitted exhaust gas. As mentioned above, this turbulence continues throughout the combustion process. Next, when the combustible mixture in the sub-combustion chamber 38 is ignited by the spark plug 26, a jet of flame flows into the lotus passage 39.
from the main combustion chamber 40. The combustible mixture in the main combustion chamber 40 is further disturbed and ignited by this flame jet. As described above, in the embodiment shown in FIG. 9, both the exhaust gas ejected through the sub-intake valve 21a and the flame jet ejected from the lotus passage 39 have a strong effect on the combustible air-fuel mixture in the main combustion chamber 40 during the combustion process. Turbulence is imparted and the combustion rate therefore becomes extremely high. As described above, according to the present invention, by injecting the exhaust gas into the cylinder at the end of the compression stroke, it is possible to generate strong turbulence that continues during the combustion process, and moreover, the exhaust gas is uniformly distributed to each cylinder. Therefore, it is possible to increase the combustion speed while ensuring the effect of reducing N○x by the EOR gas, and to obtain stable combustion without torque fluctuations or misfires.

[Brief explanation of drawings]

FIG. 1 is a plan view of an internal combustion engine according to the present invention, and FIG.
3 is a side sectional view of FIG. 1, FIG. 4 is a bottom view of the cylinder head of FIG. 3, and FIG. 5 shows the opening timings of the intake valve, exhaust valve, and sub-intake valve. Line diagram, Figure 6 is the 3rd
7 is a bottom view of the shilling head of FIG. 6, FIG. 8 is a sectional view of the shilling head of FIG. 6, and FIG. 9 is a side sectional view of the further embodiment of FIG. FIG. 4a, 4b, 4c, 4d... cylinder, 5a, 5b, 5c
, 5d... Intake valve, 6a, 6b, 6c, 6d... Exhaust valve, 20a, 20b, 20c, 20d... ECR supply branch passage, 21a, 21b, 21c, 21d... Liu intake valve, 28... storage room. - Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1. Recirculating exhaust gas supply branch passages that communicate with each cylinder of a multi-cylinder internal combustion engine are connected to a common storage chamber, and sub-intake valves are provided in each of the branch passages, and the sub-intake valves are opened during the exhaust stroke. Exhaust gas regeneration of a multi-cylinder internal combustion engine, in which high-pressure exhaust gas is temporarily stored in a storage chamber by a valve, and a sub-intake valve is opened in the latter half of the compression stroke to blow out the stored exhaust gas into the cylinders. Circulation device.