JPH025749A - Device for recirculating exhaust gas of internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce NOx in an exhaust gas while also reducing an unburned ingredient by providing an opening/closing control means for opening an exhaust-gas intake valve in the initial stage or latter stage of an exhaust stroke. CONSTITUTION:An exhaust-gas intake port 32 which is opened midway in an exhaust port 18 is provided on a cylinder head 12 and this port 32 is opened/ closed by means of an exhaust-gas intake valve 34. The exhaust-gas intake valve 34 is selectively depressed to be opened by a rocker arm 38. The rocker arm 38 is engaged with an exhaust-gas intake control cam 44 provided on a cam shaft 28. The installing positions of the nose portions 46 and 48 of the exhaust-gas intake control cam 44 with respect to a crank angle are determined in such a way that the valve opening times of the exhaust-gas intake valve 34 are immediately after an exhaust valve 20 is opened, i.e., the initial stage of an exhaust stroke and immediately before the exhaust valve 20 is closed, i.e., the latter stage of the exhaust stroke.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an exhaust gas recirculation device for an internal combustion engine used in vehicles such as automobiles.

BACKGROUND ART In order to reduce NOx, so-called exhaust gas recirculation is carried out, in which burned gas emitted from an internal combustion engine, that is, exhaust gas, is guided into the intake passage and the exhaust gas is resupplied together with the air-fuel mixture into the engine combustion chamber. is well known from the past.

Generally, an exhaust gas recirculation device connects an exhaust passage to an intake passage by an exhaust gas recirculation passage, and a flow rate control valve provided in the middle of the exhaust gas recirculation passage, that is, an exhaust gas recirculation control valve. The exhaust gas recirculation flow rate is controlled according to the operating state of the internal combustion engine.

In addition, as a special exhaust gas recirculation control device, the exhaust gas recirculation port for exhaust gas recirculation is opened directly into the engine combustion chamber, and this exhaust gas port is configured to open and close in synchronization with the engine crank angle. This has already been proposed, for example, in Utility Model Application Publication No. 54-54732.
It is shown in the publication No.

Problems to be Solved by the Invention The exhaust gas of an internal combustion engine contains unburned components such as HC in addition to NOx. is resupplied and becomes combustible.

It is known that the concentration of unburned components in the exhaust gas of an internal combustion engine is not constant even under the same operating conditions, and increases at the early and late stages of the intake stroke.

The increase in the concentration of unburned components in the exhaust gas at the beginning of the exhaust stroke is due to the outflow of unburned components around the exhaust valve, and the increase at the end of the exhaust stroke is due to the peeling of the quenching layer attached to the combustion chamber wall. And this is the company's name! B (T
Internal combustion engine Nu, 315 (1986/2 Vol.
25), pages 68-70.

In view of the characteristics of unburned components in exhaust gas as described above, the present invention selects exhaust gas with a high unburned component of 19 degrees and uses this exhaust gas as exhaust gas for exhaust gas recirculation. N inside.

It is an object of the present invention to provide an exhaust gas recirculation device that reduces unburned components in addition to reducing χ.

Means for Solving the Problems According to the present invention, an exhaust gas recirculation passage for guiding exhaust gas to an intake passage, an exhaust gas intake valve for opening and closing said exhaust gas recirculation passage, and an internal combustion This is achieved by an exhaust gas recirculation system for an internal combustion engine having an exhaust gas intake valve opening/closing control means that opens the valve at least at the beginning of the exhaust stroke or the latter half of the exhaust stroke in synchronization with the crank angle of the engine.

Effects and Effects of the Invention According to the configuration as described above, the exhaust gas for exhaust gas recirculation is selected as the exhaust gas containing a large amount of unburned components, so that the exhaust gas containing a large amount of unburned components is used for exhaust gas recirculation. The exhaust gas is re-supplied to the engine combustion chamber, and the unburned components in this exhaust gas are combusted. As a result, unburned components in the exhaust gas are reduced in addition to NOx reduction due to exhaust gas recirculation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail by way of embodiments with reference to the accompanying drawings. FIG. 1 shows one embodiment of an exhaust gas recirculation device according to the invention.

In FIG. 1, 10 indicates a cylinder block, 12 a cylinder head, 14 a piston, and 16 a combustion chamber.

The cylinder head 12 is provided with an intake boat and an exhaust boat 18 (not shown), and the exhaust boat 18 is opened and closed by an exhaust valve 20. The exhaust valve 20 is biased in the valve closing direction by a compression coil spring 22, and a rocker arm 26 whose one end is pivotally supported from the cylinder head 12 by a pivot member 24 is operated by an exhaust valve opening/closing cam 30 provided on a camshaft 28. By rotating clockwise in the figure, the valve is pushed down and opened.

The camshaft 28 is driven in synchronization with a crankshaft (not shown) of the internal combustion engine, so that the exhaust valve 20 opens according to the crank angle to set the exhaust stroke as shown in FIG. There is.

The cylinder head 12 is provided with an exhaust gas intake boat 32 that opens midway through the exhaust boat 18, and the exhaust gas intake boat 32 is opened and closed by an exhaust gas intake valve 34.

The exhaust gas intake valve 34 is biased in the closing direction by a compression coil spring 36, and selectively pushed down by a rocker arm 38 to open the valve.

The rocker arm 38 has one end pivoted from the cylinder head 12 by a pivot member 40, and is engaged with an exhaust gas intake control cam 44 provided on the camshaft 28 at a pad 42 thrown in the middle. .

The exhaust gas intake control cam 44 has two nose portions 46 and 48, and when the nose portions engage the pad 42, the rocker arm 38 rotates counterclockwise in the figure about a pivot point at one end thereof. By rotating the exhaust gas intake valve 34, the exhaust gas intake valve 34 is pushed down and opened. As shown in FIG. 2, the opening timing of the exhaust gas intake valve 34 is immediately after the exhaust valve 20 opens, that is, at the beginning of the exhaust stroke, and immediately before the exhaust valve 20 closes.
That is, the installation phase of the nose portions 46 and 48 of the exhaust gas intake control cam 44 with respect to the crank angle is determined so that the exhaust gas intake control cam 44 is in the latter half of the exhaust stroke.

The exhaust gas intake boat 32 is connected in communication with an intake passage (not shown) of the internal combustion engine by a conduit 50, a conventional exhaust gas recirculation control valve 52 for controlling the exhaust gas recirculation flow rate, and a conduit 54.

The exhaust gas recirculation control valve 52 may be a general diaphragm type, and controls the exhaust gas recirculation flow rate according to the operating state of the internal combustion engine by introducing negative pressure in the intake pipe into the diaphragm chamber. It would be good if you could do that.

According to the above-described configuration, the exhaust gas intake valve 34 opens at the beginning of the exhaust stroke and at the latter stage of the exhaust stroke, so that a part of the exhaust gas flowing through the exhaust port 18 flows to the exhaust gas intake boat 32, and this flows into the exhaust gas intake boat 32. The exhaust gas is supplied to the intake passage of the internal combustion engine through the gas recirculation control valve 52 as exhaust gas for exhaust gas recirculation. This exhaust gas contains many unburned components such as HC due to the timing of the exhaust stroke.
By being re-supplied to the combustion chamber 16 as recirculated exhaust gas, the exhaust gas containing a large amount of unburned components does not flow directly to the exhaust passage, and the catalytic converter for exhaust gas purification installed in the exhaust passage is This will help reduce the heat load.

Note that the opening timing of the exhaust gas intake valve 34 may be only at the beginning of the exhaust stroke or at the end of the exhaust stroke, as shown in Examples 2 and 3 in FIG. .

3 to 5 show another embodiment of the exhaust gas recirculation device according to the invention. In FIGS. 3 to 5, parts corresponding to those in FIG. 1 are designated by the same reference numerals as in FIG. 1. In such embodiments,
The cylinder block 10 and the cylinder head 12 are provided with an exhaust gas intake passage 70 that extends across the exhaust port 18 of each cylinder in the cylinder arrangement direction. The exhaust gas intake passage 70 has a substantially circular cross section, and communicates with the exhaust port 18 of each cylinder individually through the open lower part 2. A pipe-shaped exhaust gas intake valve 74 is rotatably provided in the exhaust gas intake passage 70 .

Exhaust boats 1 for each cylinder are arranged on the circumferential surface of the exhaust gas intake valve 74.
A valve boat 76 is provided every eight.

The valve boat 76 is selectively aligned with the open lower lower 2 by rotation of the exhaust gas intake valve 74 about its central axis, and connects exhaust gas flowing through the exhaust port 18 to an exhaust gas passage 78 within the exhaust gas intake valve 74. It is designed to be inserted. A plurality of openings 8 are provided on the circumferential surface near the end of the exhaust gas intake valve 74.
0 is provided, and this opening 80 allows the exhaust gas passage 78 in the intake valve 74 to connect to the cylinder head 1.
It communicates with an exhaust gas recirculation passage 82 provided at 2. Exhaust gas recirculation 82 is not shown in the figure, but -
It is sufficient that the exhaust gas inlet port of the exhaust gas recirculation control valve having a conventional structure is connected in communication with the exhaust gas inlet port.

A timing pulley 84 is attached to the end of the exhaust gas intake valve 74 on the side opposite to the opening 80, and an endless belt is provided between the timing pulley 84 and a timing pulley 86 attached to the camshaft 28. timing belt 88
is being handed over.

Note that the exhaust gas intake valve 74 may be operatively connected to the camshaft 28 or the crankshaft of the internal combustion engine by a timing gear or the like instead of the timing belt.

As a result, the exhaust gas intake valve 74 is driven to rotate in synchronization with the camshaft 28, in other words, in synchronization with the crank angle of the internal combustion engine. The valve ports 76 provided corresponding to the exhaust ports 18 of each cylinder are positioned in the circumferential direction of the exhaust gas intake valve 74 according to the piston phase of each cylinder. The second half of the exhaust stroke of the corresponding cylinder, for example, the crank angle is aligned with the open lower 2 over a range from 40 degrees before top dead center to 20 degrees after top dead center.

Note that the valve boat 76 may be provided in the form shown in FIG. 6 in addition to the form shown in FIG.

In the embodiment described above, the valve port 76 of the exhaust gas intake valve 74 is aligned with the open lower part 2 in the latter half of the exhaust stroke of each cylinder, so that exhaust gas is taken in for exhaust gas recirculation. , HC, and other unburned components are recirculated to the engine intake system.

In Fig. 3, 56 is an exhaust manifold, 58 is an intake boat, 60 is an intake valve, 62 is a compression coil spring, 64 is a rocker arm for the intake valve, and 66 is an intake valve opening/closing cam. are shown respectively.

FIG. 7 shows a modification of the exhaust gas intake valve structure in the exhaust gas recirculation device according to the present invention shown in FIGS. 3 to 6. In this embodiment, the exhaust gas intake valve 74 is constituted by a single solid rod-like member, and its outer peripheral surface is selectively aligned with the open lower valve 2 provided at the exhaust port 18 of each cylinder. A recessed portion 90 is provided, and the cylinder head 12 is provided with an exhaust gas intake passage 92 that extends along the extending direction of the exhaust gas intake valve 74 adjacent to the location where the exhaust gas intake valve 74 is disposed. The exhaust gas intake passage 92 selectively communicates with the exhaust port 18 through a recess 90 .

Also in this embodiment, the exhaust gas intake valve 74 is rotationally driven in synchronization with the crank angle of the internal combustion engine, and the recessed portion 90 is provided at a predetermined position corresponding to the piston phase of each cylinder. , the exhaust gas intake passage 92 communicates with the exhaust port 18 through the recess 92 only when each cylinder is in the latter half of the exhaust stroke, and exhaust gas is taken in for exhaust gas recirculation only at that predetermined time. , the same effects as those of the above-mentioned embodiments can be obtained.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited to these, and it is understood that various embodiments can be made within the scope of the present invention. It will be clear to those skilled in the art.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing one embodiment of the exhaust gas recirculation device according to the present invention, and Fig. 2 shows the unburned component concentration characteristics in the exhaust stroke and the opening timing of the exhaust gas intake valve related thereto. 3 is a vertical sectional view showing another embodiment of the exhaust gas recirculation device according to the present invention, and FIG. 4 is a graph used in the exhaust gas recirculation device according to the present invention shown in FIG. 3. 5 and 6 are respectively enlarged longitudinal sectional views of the exhaust gas intake valve structure shown in FIG. 4, and FIG. 7 is a schematic plan view of the exhaust gas intake valve structure shown in FIG. FIG. 7 is a longitudinal sectional view showing another example of the exhaust gas intake valve structure used. 10... Cylinder block, 12... Cylinder head, 14... Piston, 16... Combustion chamber, 18...
・Exhaust port, 20...Exhaust valve, 22...Compression coil spring. 24... Pivotal support member, 26... Rocker arm, 28
...Camshaft, 30...Cam for opening and closing exhaust valve, 32...
・Exhaust gas intake port, 34... Exhaust gas intake valve, 36... Compression coil spring, 38... Rocker arm, 40... Ward branch material, 42... Pad, 44...
- Exhaust gas intake control cam, 46.48... nose section, 50... conduit. 52... Exhaust gas recirculation control valve, 54... Conduit, 5
6...Exhaust manifold, 58...Intake port, 5
8...Intake valve, 62...Compression coil spring, 64...
・Rocker arm, 66...Intake valve opening/closing cam, 70
...Exhaust gas intake passage, 72...Opening, 74...
・Exhaust gas intake valve, 76... Valve port, 78...
Exhaust gas passage, 80... Opening, 82... Exhaust gas recirculation passage, 84. 86... Timing pulley, 88.
··Timing belt. 90... Recessed portion, 92... Exhaust gas intake passage first
Figure Figure Figure 3 Y6 --- Te f button

Claims (1)

[Claims] an exhaust gas recirculation passage that guides exhaust gas to the intake passage; an exhaust gas intake valve that opens and closes the exhaust gas recirculation passage; and an exhaust gas intake valve that opens and closes the exhaust gas recirculation passage; an exhaust gas recirculation device for an internal combustion engine, comprising a valve opening/closing control means that occasionally opens the exhaust gas intake valve.