JP2023056916A - internal combustion engine - Google Patents

Abstract

To enable great supercharging of intake air of an exhaust turbo supercharger attached to an internal combustion engine and keep a high purification effect for harmful substances in exhaust by a three-way catalyst.SOLUTION: In an internal combustion engine accompanied by an exhaust turbo supercharger 2, there are provided, in an exhaust channel through which exhaust discharged from a cylinder passes, a catalyst 1 for exhaust purification, a turbine of the supercharger 2 disposed downstream of the catalyst 1, and a return flow channel 3 which is connected to the downstream of the turbine and guides the exhaust passing through the turbine to a portion adjacent to the catalyst 1.SELECTED DRAWING: Figure 5

Description

The present invention relates to an internal combustion engine with an exhaust turbocharger.

The energy of the exhaust gas discharged from the cylinders of the internal combustion engine is used to rotate the exhaust turbine (turbine wheel), and the rotation is transmitted to the compressor impeller (compressor wheel) to pressurize and compress the intake air (supercharging). ) to feed the exhaust gas into the cylinder.

There is also an external EGR device that connects an exhaust passage and an intake passage of an internal combustion engine via an EGR (Exhaust Gas Recirculation) passage, recirculates a part of the exhaust gas to the intake passage via the EGR passage, and mixes it with the intake air. Widely adopted. By using EGR, the combustion temperature in the cylinder can be lowered to reduce the emission amount of _NOx , which is a harmful substance, and at the same time, it is possible to reduce the pumping loss (see the following patent documents).

JP 2013-155686 A

The EGR rate, which is the ratio of EGR gas in the intake air, is dramatically increased (eg, over 30%), or the air-fuel ratio is made leaner than the theoretical air-fuel ratio (eg, air-fuel ratio λ≧2) to reduce fuel consumption. is reduced, the temperature of the gas discharged from the cylinder is significantly lowered. The temperature of the exhaust gas may be 350° C. or less.

If the amount of heat energy contained in the exhaust gas supplied to the turbine of the exhaust turbocharger is small, the efficiency of the turbocharger will decrease and the work of supercharging the intake air will decrease. In addition, the heat energy is taken away in the process of passing through the turbine, and the temperature of the exhaust gas, which is further cooled, flows into the three-way catalyst, which causes the temperature of the catalyst to drop, and the harmful substances HC, CO, and _NOx contained in the exhaust gas are reduced. There is also concern that the oxidation/reduction reaction will be inhibited.

SUMMARY OF THE INVENTION It is an object of the present invention to enable an exhaust turbocharger to sufficiently perform the work of supercharging intake air, and to maintain a high purification efficiency of harmful substances in exhaust gas by a three-way catalyst.

In the present invention, in an internal combustion engine with an exhaust turbosupercharger, a catalyst for purifying exhaust gas and a supercharger disposed downstream of the catalyst are provided in an exhaust passage through which exhaust gas discharged from a cylinder flows. A turbine and a return path connected to the downstream of the turbine and guiding the exhaust that has passed through the turbine to a location close to the catalyst are provided.

Preferably, the catalyst and the turbine are arranged side by side on the side of the internal combustion engine.

It is preferable that the return channel is arranged so as to penetrate through the inside of the catalyst.

According to the present invention, the exhaust gas turbocharger attached to the internal combustion engine can sufficiently perform the task of supercharging the intake air, and the three-way catalyst can maintain a high purification efficiency of harmful substances in the exhaust gas.

1 is a side view of an internal combustion engine according to one embodiment of the present invention; FIG. FIG. 2 is a perspective view showing the appearance of the exhaust turbosupercharger and the catalyst case of the internal combustion engine of the same embodiment; FIG. 2 is a front view showing the appearance of the exhaust turbosupercharger and the catalyst case of the internal combustion engine of the same embodiment; FIG. 2 is a sectional view taken along the line AA of the catalyst case of the internal combustion engine of the same embodiment; FIG. 2 is a cross-sectional view taken along line BB of the catalyst case of the internal combustion engine of the same embodiment;

One embodiment of the present invention will be described with reference to the drawings. The internal combustion engine 0 of this embodiment is a four-stroke reciprocating engine having a plurality of cylinders (for example, three cylinders). FIG. 1 shows a side view of an internal combustion engine 0 of this embodiment. The cylinders of the internal combustion engine 0 are arranged side by side along the left-right direction in FIG. 1, and the crankshaft, which is the output shaft of the internal combustion engine 0, extends along the left-right direction in FIG.

Exhaust gas generated by burning fuel in each cylinder of the internal combustion engine 0 is discharged outside the internal combustion engine 0 through an exhaust port opened in the cylinder head. An exhaust port communicating with each cylinder opens on the front side in FIG. These exhaust ports are also arranged along the left-right direction in FIG.

An exhaust manifold, which is a collecting pipe, is connected to each exhaust port, and the exhaust gas discharged from each cylinder is joined at the exhaust manifold. An outlet of the exhaust manifold is connected to an inlet 12 of a catalyst case 11 containing a three-way catalyst for exhaust purification. That is, the exhaust gas that has flowed through the exhaust manifold flows into the catalyst case 11 through the inlet 12 . As a supplement, the reason why the exhaust manifold is not shown is that the exhaust manifold exists on the far side of the catalyst case 11 in FIG. 1 and is hidden by the catalyst case 11 .

As shown in FIGS. 2 to 5, the catalyst case 11 is a cylindrical body that extends parallel or substantially parallel to the direction in which the cylinders of the internal combustion engine 0 and their intake ports are arranged, in other words, the extension direction of the crankshaft. be. The inlet 12 of the catalyst case 11 is positioned on one end side of the catalyst case 11, i.e., on the right end side in FIGS. An inlet 12 of the catalyst case 11 protrudes in a direction perpendicular or substantially perpendicular to the extending direction of the catalyst case 11 and connects to an outlet of the exhaust manifold.

The three-way catalyst for purifying exhaust gas mounted in the catalyst case 11 is made by carrying precious metals such as platinum, palladium, and rhodium on a ceramic carrier 13 coated with alumina or the like, similar to known ones. is. The carrier 13 expands along a direction parallel or substantially parallel to the extending direction of the catalyst case 11 . Inside, there are formed a large number of small holes penetrating along the same direction to allow the exhaust gas to flow.

In this embodiment, at the center of the carrier 13 of the catalyst 1 , a large-diameter axial hole is drilled through the carrier 13 along a direction parallel or substantially parallel to the extending direction of the catalyst case 11 . That is, the carrier 13 is shaped like a doughnut or Baumkuchen. A return flow path 3, which will be described later, is provided in this shaft hole.

As indicated by arrows in FIG. 4 , the exhaust gas that has flowed into the catalyst case 11 from the exhaust manifold flows through the carrier 13 of the catalyst 1 . At this time, the oxidation/reduction reaction of the harmful substances HC, CO, and _NOx contained in the exhaust gas is accelerated, and the harmful substances change into harmless substances, that is, the exhaust gas is purified.

The turbine of the exhaust turbosupercharger 2 is connected to the other end side of the catalyst case 11, which is the left end side in FIGS. After passing through the catalyst 1, the exhaust gas flows directly into this turbine.

The exhaust turbocharger 2 uses the energy of the exhaust gas to rotate the turbine, transmits the rotation to the impeller of the compressor, and pressurizes and compresses the intake air flowing through the intake passage by the compressor, that is, supercharges it. It is well known in the art to feed into the cylinder.

5, the exhaust gas that has passed through the turbine of the exhaust turbosupercharger 2 flows into the return passage 3 piped through the carrier 13 of the catalyst 1, Along this return flow path 3, the catalyst 1 flows in the opposite direction. The carrier 13 of the catalyst 1 is in contact with or very close to the outer circumference of the pipe of the return flow path 3 . Finally, the exhaust gas is directed from the outlet of the return passage 3 to the muffler and discharged to the outside.

In this embodiment, in an internal combustion engine 0 with an exhaust turbosupercharger 2, a catalyst 1 for purifying exhaust gas and a A turbine of the supercharger 2 and a return passage 3 connected downstream of the turbine and guiding the exhaust that has passed through the turbine to a location close to the catalyst 1 are provided.

If the catalyst 1 for purifying exhaust gas is arranged downstream of the exhaust manifold and upstream of the exhaust turbocharger 2, it is possible to prevent extremely low temperature gas from flowing into the catalyst 1. As a result, the temperature drop of the catalyst 1 can be suppressed, the activity of the catalyst 1 can be maintained, and the purification efficiency of harmful substances in the exhaust gas can be kept high. Even when the temperature of the catalyst 1 is low, such as when the internal combustion engine 0 is cold-started, the temperature rise can be accelerated.

In addition, a return passage 3 for circulating exhaust gas that has passed through the catalyst 1 and the turbine is piped at a location close to or adjacent to the catalyst 1 . Even the exhaust gas that has flowed down from the turbine does not reach a temperature as cold as the outside air temperature (normal temperature), and still has a certain level of high temperature. By flowing this in the vicinity of the catalyst 1, the catalyst 1 is kept warm, the amount of heat taken by the catalyst 1 from the exhaust gas flowing into the turbine through the catalyst 1 is reduced, and the efficiency of the turbocharger 2 is reduced. can be suppressed, thereby increasing the work of supercharging the intake air.

In this embodiment, the catalyst 1 and the turbine are arranged side by side on the side of the internal combustion engine 0 . By directly connecting the exhaust manifold directly upstream of the catalyst case 11 and directly connecting the turbine directly downstream of the catalyst case 11, the amount of heat energy that the exhaust gas has before flowing into the turbine escapes can be reduced. You can further strengthen the work of supercharging by. In addition, the exhaust passage can be made compact, leading to elimination of unnecessary members.

The catalyst case 11 and the return path 3 each extend parallel or substantially parallel to the direction in which the exhaust ports of the cylinders are arranged. The catalyst case 11 and the return channel 3 are close to the exhaust manifold and the upper side surface of the cylinder head and/or cylinder block of the internal combustion engine 0 . The temperature of the exhaust manifold, cylinder head, and cylinder block during operation of the internal combustion engine 0 is naturally high. Get even higher.

In general, even if the EGR rate of the intake air is increased or the air-fuel ratio is made leaner to perform lean burn, the supercharger 2 can sufficiently perform the work of supercharging the intake air, and the catalyst 1 can reduce the harmful substances in the exhaust gas. It is possible to keep the purification efficiency high.

The present invention is not limited to the embodiments detailed above. For example, in the above-described embodiment, the carrier 13 of the catalyst 1 has a cylindrical shape, and the return channel 3 runs through it, but the inside and outside of the catalyst and the return channel may be reversed. That is, an annular return flow path may be provided adjacent to or close to the outer circumference of the catalyst. In any case, the gist of the present invention is to keep the catalyst warm by the residual heat of the exhaust gas flowing in the return passage.

In addition, the specific configuration of each part can be modified in various ways without departing from the gist of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be applied to an internal combustion engine mounted on a vehicle or the like.

0... Internal combustion engine 1... Catalyst 2... Exhaust turbocharger 3... Return path

Claims (3)

An internal combustion engine accompanied by an exhaust turbocharger,
A catalyst for purifying exhaust gas, a turbine of a supercharger arranged downstream of the catalyst, and a turbine connected downstream of the turbine in an exhaust passage through which exhaust gas discharged from a cylinder flows are placed near the catalyst. An internal combustion engine provided with a return path leading to a point where the 2. The internal combustion engine of claim 1, wherein said catalyst and said turbine are arranged adjacently on a side of said internal combustion engine. 3. The internal combustion engine according to claim 1, wherein said return passage runs through said catalyst.

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