JPS6210424Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an exhaust gas purification device for an internal combustion engine, and more particularly to an exhaust gas purification device that improves the exhaust gas sensing capability of an oxygen sensor.

In modern exhaust purification systems, an exhaust manifold with a catalytic converter is used, in which the catalytic converter is placed directly below the exhaust manifold, in order to reduce heat dissipation in the middle of the exhaust passage and improve warm-up of the catalytic converter. There is a tendency. In an exhaust manifold with a catalytic converter, the oxygen sensor is provided in an expansion chamber located in the center of the exhaust manifold. In this case, the element part of a conventional oxygen sensor cannot be made too long in order to prevent it from vibrating under pressure from the exhaust gas flow. Since they were disposed in areas that were not directly exposed to the main stream, their sensitivity to exhaust gases was not necessarily good, which was a disadvantage in achieving sufficient exhaust gas control.

In order to improve this point, the present invention aims to improve the exhaust gas sensing ability of the oxygen sensor by improving the arrangement of the oxygen sensor detection section in the expansion chamber.

In order to achieve this purpose, in the exhaust gas purification device of the present invention, the expansion chamber located in the center of the exhaust manifold is made into a hemispherical shape, and the oxygen sensor element is inserted into the expansion chamber from the expansion chamber wall. It protrudes, and the tip of the element part is attached toward the spherical center of the spherical expansion chamber. In this way, the oxygen sensor element portion approaches the center of the sphere where mixing is most favorable, and the oxygen concentration of the exhaust gas is detected with good sensitivity.

Preferred embodiments of the exhaust purification device of the present invention will be described below with reference to the drawings.

1 to 4 show an exhaust purification device according to an embodiment of the present invention for a four-cylinder engine. In Fig. 1, 1 is an exhaust manifold;
2 is the intake manifold, and the exhaust manifold is
It is connected to a catalytic converter 4 provided directly below the expansion chamber 3 via an expansion chamber 3 with an enlarged passage cross-sectional area located in the center thereof.

As shown in FIGS. 2 to 4, the exhaust manifold 1 includes #1 to #4 exhaust ports 5, 6, which are connected to the #1 to #4 cylinders of the cylinder head.
It has left and right twin tube sections 9 and 10 consisting of left and right tube sections 7 and 8, and left and right curved passage sections 11 and 12 that are connected downstream of the twin tube sections 9 and 10 and direct the flow toward the expansion chamber 3 side, The curved passage portions 11 and 12 open into the expansion chamber 3 from the left and right sides. Expansion chamber 3 of one curved passage section 12
A heat control valve 13 that is rotated by, for example, a bimetal and changes the flow to the riser portion side during a cold start is attached to the port opening to the engine. Since the curved passage section 12 on the side to which the heat control valve 13 is attached has a longer passage length than the other curved passage section, the expansion chamber 3 is connected to the curved passage section 12 on which the heat control valve 13 is attached. is put on the opposite side.

As shown in FIGS. 2 and 3, the expansion chamber 3 is formed into a roughly hemispherical shape, with one curved passage section 12 opening horizontally into the upper part of the expansion chamber 3, and the other curved passage section 12 opening horizontally into the upper part of the expansion chamber 3. The curved passage portion 11 opens toward the spherical center O of the hemispherical expansion chamber 3. Expansion room 3
A mounting hole and a mounting seat for an oxygen sensor are provided in the wall opposite to the cylinder head, and the oxygen sensor 14 is mounted here. The element part 14a of the oxygen sensor 14 extends into the expansion chamber 3 by passing through a hole in the wall, and its tip faces the spherical center O of the hemispherical expansion chamber 3. It extends toward the center O.

The catalytic converter 4 installed directly below the expansion chamber 3 is installed with its catalyst inclined in the direction of the exhaust gas flow, so that the exhaust gas flows uniformly to the catalyst.

In the exhaust purification device configured as described above, exhaust gas flows from the exhaust manifold 1 through the expansion chamber 3 to the catalytic converter 4.

In this case, the flow of exhaust gas when the heat control valve 13 is in the open position shown by the solid line in the figure is as follows. That is, when exhaust gas flows into the expansion chamber 3 from the curved passages 11 and 12 of the exhaust manifold 1, the ignition order is #1, #3,
Since the #4 and #2 cylinders are in that order, the exhaust gas that flows from the #3 and #4 cylinders into the expansion chamber 3 through one of the curved passages 12 with horizontal directionality flows into the #4 cylinder immediately after that. 2. From #1 cylinder to the other curved passage section 1
1 into the expansion chamber 3 toward the ball center O, the ball center O has the best mixing of the exhaust gases from both curved passages 11 and 12. This is a region where the gas flow does not stagnate.

Also, the heat control valve 13 is
When in the closed position shown by the dotted chain line, the flow that has passed through the curved passage section 12 passes through the gap between the upper end of the heat control valve 13 and the bottom back side of the riser section of the intake manifold 2 to the expansion chamber 3. However, this flow is directed toward the center O of the sphere by the exhaust gas flow from the other curved passage section 11, so the mixing of the exhaust gas that has passed through both passages 11 and 12 near the center O of the sphere is good. And there is no stagnation in the flow.

Since the element part 14a of the oxygen sensor 14 is mounted toward the center O of the sphere, the oxygen sensor 14 detects the oxygen concentration of the exhaust gas that is well mixed and flows without stagnation. The changing oxygen concentration can be detected with good responsiveness and with high precision without being strongly influenced by the exhaust gas from only one of the curved passages 11 and 12.

As described above, when using the exhaust gas purification device of the present invention, the expansion chamber is formed into a hemispherical shape and the horizontal flow from one curved passage is pushed down by the flow from the other curved passage. By directing the flow toward the center of the sphere and by mounting the oxygen sensor element toward the center of the sphere in the expansion chamber, the response and accuracy of oxygen concentration detection can be accelerated and the accuracy of the exhaust purification control improved. This has the effect of improving performance.

[Brief explanation of drawings]

Figure 1 is an overall perspective view of the exhaust purification device of the present invention.
Fig. 2 is a plan view showing a cross section of a part of the exhaust manifold of the exhaust purification device of the present invention, and Fig. 3 is a front view showing a part of the exhaust manifold part of Fig. 2 in cross section. 4 is a side view showing a part of the exhaust manifold shown in FIG. 2 in cross section. 1... Exhaust manifold, 3... Expansion chamber, 11,
12... Curved passage section, 13... Heat control valve, 14... Oxygen sensor, 14a... Oxygen sensor element section, O... Expansion chamber sphere center.

Claims (1)

[Scope of utility model registration request] In an exhaust purification device in which an exhaust manifold is connected to a catalytic converter disposed directly below an expansion chamber disposed in the center of the exhaust manifold through the expansion chamber, the expansion chamber is formed in a hemispherical shape, and a #3 expansion chamber is connected to cylinders whose ignition order is #1, #3, #4, and #2.
The curved passage of the collecting passage connected to the twin pipe section consisting of the exhaust port and the #4 exhaust port is opened to the extension chamber from one of the left and right directions almost horizontally, and
An exhaust purification device characterized in that a curved passage portion of a collecting passage connected to a twin pipe portion consisting of an exhaust port and a #2 exhaust port is opened toward the center of a hemisphere of the expansion chamber from the other of the left and right directions into the expansion chamber, and an oxygen sensor is attached extending toward the center of the hemisphere of the expansion chamber.