JP2018159344A - Multi-cylinder internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine which can purify an exhaust gas immediately after a start by a simple structure.SOLUTION: A plurality of pairs of exhaust ports 8 corresponding to cylinder bore 2, respectively, an aggregate exhaust passage 10 communicating with each exhaust port 8, and an exhaust outlet hole 11 for discharging an exhaust gas which flows into the aggregate exhaust passage 10 to the outside are formed at a cylinder head 3, and an auxiliary purification unit 21 is arranged in the exhaust outlet hole 11. Since the exhaust gas discharged to each exhaust port 8 directly and non-intermittently abuts on the auxiliary purification unit 21 at a high temperature, the exhaust gas can be purified immediately after a start. Since the auxiliary purification unit 21 is merely arranged in the exhaust gas discharge hole 11, a structure is simplified and not enlarged in size.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a multi-cylinder internal combustion engine equipped with an exhaust gas purification device.

  In an internal combustion engine (gasoline engine), a catalytic purification device is used to purify exhaust gas. The catalytic purification device has a characteristic that the catalyst is not activated unless the temperature is raised to a certain temperature. However, since the purification device is disposed at a site downstream of the cylinder head, the exhaust gas is exhausted immediately after starting. There is a problem that it is difficult to quickly raise the temperature of the catalyst because the heat of the gas is absorbed by the members constituting the exhaust passage.

  With respect to this point, in Patent Document 1, a pair of exhaust ports corresponding to each cylinder is opened on the exhaust side of the cylinder head, and an exhaust manifold having branch pipes communicating with each exhaust port is fixed to the cylinder head. In the internal combustion engine, the purification device includes a main catalytic converter provided on the downstream side of the exhaust manifold and a warm-up catalytic converter disposed in the exhaust port or a branch pipe of the exhaust manifold, and one of the pair of exhaust ports. Is configured so that exhaust gas flows to the main catalytic converter from the other side and flows to the warm-up catalytic converter from the other side, and when starting, the exhaust gas flows to the warm-up catalytic converter and the main catalytic converter is heated to the activation temperature. Controlling the opening and closing of the exhaust valve so that the exhaust gas flows to the main catalytic converter It is.

JP-A-3-33410

  Although it can be said that Patent Document 1 can appropriately purify the exhaust gas immediately after start-up using a warm-up catalytic converter, the structure is remarkably complicated, so that the cost increase and the engine size are inevitable. In addition, since only one of the pair of exhaust ports is used, there is a concern that the cylinder head is biased and the temperature rises and a large thermal distortion occurs, and that the exhaust gas flow resistance is large and it is difficult to ensure high output. Is done. For this reason, reality is a serious question.

  The present invention has been made to improve the current situation.

  The multi-cylinder internal combustion engine of the present invention has a cylinder head, an external exhaust passage connected to the exhaust side of the cylinder head, and a catalytic exhaust gas purification device provided in the exhaust gas flow path.

  The cylinder head includes a group of exhaust ports respectively formed corresponding to a plurality of cylinders, a collective exhaust passage through which exhaust gas flows from the plurality of exhaust ports, and communicates with the collective exhaust passage on the exhaust side surface. An exhaust outlet hole that is open, and an external exhaust passage is connected to the exhaust outlet hole, wherein the exhaust gas purification device is disposed in a middle portion of the external exhaust passage. And an auxiliary purification unit arranged so that at least a part thereof is accommodated in the exhaust outlet hole of the cylinder head.

  The present invention is directed to a cylinder head with a built-in collective exhaust passage, and an auxiliary purification unit is disposed at an exhaust outlet hole through which exhaust gas discharged from a plurality of exhaust ports is discharged. Is simple and requires no control. Therefore, the cost can be suppressed and the size is not increased. Since the exhaust gas is also purified by the auxiliary purification unit, the main purification unit can be downsized. In this case, the engine can be made compact as a whole.

  Since the hottest exhaust gas flows directly into the exhaust outlet hole directly and without interruption, the auxiliary purification unit is heated to the activation temperature almost simultaneously with the start of the engine, and the exhaust gas is immediately after the start. Can be purified. In addition, since the cylinder head has a high heat storage property, it is possible to keep the auxiliary purification unit warm by the cylinder head after the engine stops. For example, when restarting after several tens of minutes, the auxiliary purification unit is activated early. Can be further speeded up.

  Further, since the flow of the exhaust gas is rectified by the auxiliary purification unit, and the exhaust gas flows into the external exhaust passage in a so-called uniform stirring state, a sensor (A / F sensor) arranged upstream of the main purification unit As well as improving the detection accuracy of the exhaust gas, it is possible to improve the durability by using the main purification unit evenly (eliminating the phenomenon of exhaust gas per side contact).

It is the partially broken side view which looked at the principal part of 1st Embodiment from the direction orthogonal to the crankshaft axis. It is the II-II sectional view taken on the line of FIG. It is the III-III sectional view taken on the line of FIG. (A) is a principal part cross-sectional view of 2nd Embodiment, (B) is a principal part flat sectional view of 3rd Embodiment.

  Next, an embodiment of the present invention will be described with reference to the drawings. This embodiment is applied to a three-cylinder internal combustion engine. Therefore, as shown in FIGS. 1 and 3, three cylinder bores 2 are formed in the cylinder block 1, and a cylinder bore 2 and a cylinder bore 2 are formed in the cylinder head 3. There are three ignition device insertion holes 4 concentrically. A plurality of cooling water jackets 5 are formed in the cylinder head 3.

  The cylinder head 3 is formed with a triangular pyramid-shaped combustion chamber 6 concentric with the cylinder bore 2, and a pair of intake ports 7 and an exhaust port 8 start end are opened in the combustion chamber 6. The intake ports 7 are independent, or two merge into one and open to the intake side surface 2a. As shown in FIG. 3, the group of exhaust ports 8 is one set long in the crank axis direction. It communicates with the exhaust passage 10. A single exhaust outlet hole 11 communicates with the collective exhaust passage 10, and the exhaust outlet hole 11 opens on the exhaust side surface 2 b of the cylinder head 3.

  The exhaust outlet holes 11 are arranged at the front and rear intermediate portions of the collective exhaust passage 10, and have an oval shape in a side view as shown in FIG. A maniverter 15 in which the catalyst case 13 and the upper exhaust pipe 14 are integrated is fixed to the exhaust side surface 2 b of the cylinder head 3. A flange plate 16 is fixed to the tip of the upper exhaust pipe 14, and the flange plate 16 is fixed to the exhaust side surface 2b with a bolt 17 and a nut 18 via a gasket (not shown) (with a headed bolt). It may be fixed.) The manipulator 15 constitutes an external exhaust passage.

  The upper exhaust pipe 14 is bent downward from the lateral projection, and the catalyst case 13 is fixed to the lower end thereof by welding or brazing. The catalyst case 13 has upper and lower cone portions 13a, and a main purification unit (main catalyst) 19 is disposed on the straight portion. An A / F sensor 20 is attached to the upper cone portion 13a.

  A flat auxiliary purification unit 21 is disposed in the exhaust outlet hole 11 of the cylinder head 3. The auxiliary purification unit 21 has a configuration in which the catalyst is held by a ring frame 22 made of a metal plate, and the stopper portion 23 located at the back end of the exhaust outlet hole 11 is prevented from moving into the collective exhaust passage 10. Yes. The tip of the upper exhaust pipe 14 is in contact with or close to the outer end surface of the ring frame 22. Therefore, the auxiliary purification unit 21 is held so that it cannot be removed in any direction. The auxiliary purification unit 21 can also be attached by forcibly fitting the ring frame 22 to the exhaust outlet hole 11.

  In FIG. 3, reference numeral 24 indicates a head bolt insertion hole, and reference numeral 25 indicates a valve shaft insertion hole. A portion of the cylinder head 3 where the collective exhaust passage 10 is provided swells outward. The collective exhaust passage 10 is gently curved in plan view so as to move away from the combustion chamber 6 as it approaches the exhaust outlet hole 11.

  In the above configuration, the exhaust gas discharged from each exhaust port 8 directly hits the auxiliary purification unit 21. For this reason, the auxiliary purification unit 21 is hit with high-temperature gas that is hardly absorbed by the cylinder head 3 without interruption. For this reason, it is possible to appropriately purify the exhaust gas immediately after starting by raising the temperature to the activation temperature almost simultaneously with starting.

  The exhaust gas that has passed through the auxiliary purification unit 21 flows into the catalyst case 13 from the upper exhaust pipe 14 and raises the temperature of the main purification unit 19. Since the temperature of the main purification unit 19 is also rapidly increased, the exhaust gas is appropriately purified by the double action of the auxiliary purification unit 21 and the main purification unit 19.

  Since the cylinder head 3 is a type having the built-in exhaust passage 10, the heat dissipation to the outside of the cylinder head 3 is low, and the temperature of the cylinder head 3 itself rises early. For this reason, even in the cold start, the exhaust gas that hits the auxiliary purification unit 21 is maintained at a high temperature immediately after the start. Therefore, the auxiliary purification unit 21 can be activated almost simultaneously with the start, and the exhaust gas can be appropriately purified immediately after the start.

  Further, since the structure incorporating the collective exhaust passage 10 is effectively used, the structure is simple, the cost can be greatly suppressed, and the cylinder head 3 is not increased in size. In addition, the auxiliary | assistant purification | cleaning unit 21 is formed in the porosity which exhaust gas passes smoothly.

  In the second embodiment shown in FIG. 4A, the auxiliary purification unit 21 is disposed across the exhaust outlet hole 11 and the upper exhaust pipe 14. Thus, extending the auxiliary purification unit 21 to the upper exhaust pipe 14 has the advantage of increasing the volume and improving the purification performance.

  Also in the third embodiment shown in FIG. 4B, the auxiliary purification unit 21 is disposed across the exhaust outlet hole 11 and the upper exhaust pipe 14, but in this embodiment, the auxiliary purification unit 21 is disposed. , It is curved so as to be recessed toward the collective exhaust passage 10. This embodiment has an advantage that the exhaust gas flow into the auxiliary purification unit 21 becomes good, and the flow of the exhaust gas can be made smooth. In the present embodiment, the rear surface on the downstream side of the auxiliary purification unit 21 is also curved, but only the front surface facing the collective exhaust passage 10 may be recessed.

Further, in this embodiment, the upper exhaust pipe 14 is extended to the location of the exhaust outlet hole 11, and the auxiliary purification unit 21 is fixed to the upper exhaust pipe 14. Therefore, when the upper exhaust pipe 14 is attached to the cylinder head 3, the auxiliary purification unit 21 is automatically set.

  The present invention can be embodied in various ways other than the above-described embodiment. For example, it can be applied to a two-cylinder internal combustion engine. In the case of an internal combustion engine having four or more cylinders, it is possible to provide a plurality of pairs of exhaust passages so that a plurality of pairs of exhaust ports communicate with each of the collective exhaust passages.

  The present invention can actually be embodied in an internal combustion engine. Therefore, it can be used industrially.

DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Cylinder bore 2b Exhaust side surface 3 Cylinder head 8 Exhaust port 9 Exhaust side surface 10 Collective exhaust passage 11 Exhaust outlet hole 13 Catalyst case 14 Upper exhaust pipe 15 Maniverter 19 Main purification unit (main catalyst)
21 Auxiliary purification unit (auxiliary catalyst)

Claims (1)

A cylinder head, an external exhaust passage connected to the exhaust side of the cylinder head, and a catalytic exhaust gas purification device provided in the exhaust gas flow path,
A group of exhaust ports respectively formed corresponding to a plurality of cylinders in the cylinder head, a collective exhaust passage through which exhaust gas flows from the plurality of exhaust ports, and an exhaust side opening that communicates with the collective exhaust passage. An exhaust outlet hole is formed, and an external exhaust passage is connected to the exhaust outlet hole,
The exhaust gas purification device is composed of a main purification unit disposed in the middle part of the external exhaust passage, and an auxiliary purification unit disposed so that at least a part thereof is accommodated in an exhaust outlet hole of the cylinder head.
Multi-cylinder internal combustion engine.

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