JP7666340B2 - Exhaust pipe structure - Google Patents

Description

This invention relates to an exhaust pipe structure.

For example, Japanese Patent Application Laid-Open No. 2009-13865 discloses an exhaust purification device for an internal combustion engine that includes an internal combustion engine, an exhaust passage, and a NOx catalyst. The exhaust passage branches into a first exhaust passage and a second exhaust passage, a first turbocharger is disposed in the first exhaust passage, and a second turbocharger is disposed in the second exhaust passage. The first exhaust passage and the second exhaust passage merge downstream of the first turbocharger and the second turbocharger and upstream of the NOx catalyst.

JP 2009-13865 A

In an exhaust gas purification device for an internal combustion engine such as that described in JP 2009-13865 A, there are cases where the exhaust gas flowing toward the catalyst is biased. In such cases, the exhaust gas flow stagnates upstream of the catalyst, and deposits build up near the stagnation, raising concerns that the catalyst may not be able to sufficiently purify the exhaust gas.

The object of the present invention is to provide an exhaust pipe structure that can suppress a decrease in the exhaust purification effect of the catalyst.

An exhaust pipe structure according to one aspect of the present invention includes an exhaust path through which exhaust from an internal combustion engine flows, and a guide member that is provided in the exhaust path and guides the exhaust toward a catalyst that purifies the exhaust. The exhaust path has a turbocharger arrangement section in which a turbocharger can be arranged, an enlarged section that is provided downstream of the turbocharger arrangement section in the exhaust flow direction and in which the exhaust flow passage area gradually increases toward the downstream in the exhaust flow direction, and a catalyst arrangement section that is connected to the downstream end of the enlarged section and in which the catalyst is arranged. The guide member is provided in the enlarged section and guides the exhaust in a direction along a center line that includes the central axis of the enlarged section and in a direction toward the outside in a direction perpendicular to the center line.

This invention provides an exhaust pipe structure that can prevent a decrease in the exhaust purification effect of the catalyst.

1 is a diagram illustrating an internal combustion engine system including an exhaust pipe structure according to an embodiment of the present invention; 2 is a cross-sectional view taken along line II-II in FIG.

The embodiment of the present invention will be described with reference to the drawings. Note that in the drawings referred to below, the same or equivalent components are given the same numbers.

Figure 1 is a schematic diagram of an internal combustion engine system including an exhaust pipe structure of one embodiment of the present invention. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. As shown in Figure 1, the internal combustion engine system 1 includes an internal combustion engine 2, a turbocharger 3, another turbocharger 4 different from the turbocharger 3, a catalyst 5, and an exhaust pipe structure 10.

In this embodiment, the internal combustion engine 2 has a V-shaped two-bank structure. The turbocharger 3, the other turbocharger 4, and the catalyst 5 are attached to the exhaust pipe structure 10. In this embodiment, the turbocharger 3 is set as a primary turbocharger, and the other turbocharger 4 is set as a secondary turbocharger. The catalyst 5 purifies the exhaust gas from the internal combustion engine 2. An example of the catalyst 5 is an oxidation catalyst (DOC).

The exhaust pipe structure 10 is connected to the internal combustion engine 2. The exhaust pipe structure 10 includes an exhaust path 100, a switching member 200, and a guide member 300.

The exhaust path 100 is connected to the internal combustion engine 2, and exhaust from the internal combustion engine 2 flows through it. The exhaust path 100 has a turbocharger arrangement section 110, another turbocharger arrangement section 120, a junction section 130, an expansion section 140, and a catalyst arrangement section 150.

The turbocharger mounting section 110 is a section where the turbocharger 3 can be mounted. The other turbocharger mounting section 120 is a section where the other turbocharger 4 can be mounted. The other turbocharger mounting section 120 is connected to the internal combustion engine 2 so as to be in parallel with the turbocharger mounting section 110.

The junction section 130 is formed downstream of the turbocharger arrangement section 110 and the other turbocharger arrangement section 120. The junction section 130 merges the exhaust gas that has passed through the turbocharger arrangement section 110 with the exhaust gas that has passed through the other turbocharger arrangement section 120.

The expansion section 140 is provided downstream of the turbocharger arrangement section 110 in the exhaust flow direction. More specifically, the expansion section 140 is connected to the downstream end of the junction section 130 in the exhaust flow direction. In other words, the junction section 130 is formed downstream of the turbocharger arrangement section 110 and the other turbocharger arrangement section 120 and upstream of the expansion section 140. The expansion section 140 has a gradually larger exhaust flow passage area toward the downstream in the exhaust flow direction.

The catalyst placement section 150 is connected to the downstream end of the expansion section 140. The catalyst placement section 150 is capable of placing the catalyst 5. The catalyst placement section 150 may be formed in a cylindrical shape. The inner diameter of the catalyst placement section 150 may be formed to be constant.

The switching member 200 is provided in the exhaust path 100. As shown in FIG. 1, the switching member 200 is provided, for example, in a portion downstream of a portion of the other turbocharger arrangement portion 120 where the other turbocharger 4 is located. The switching member 200 can be switched between a first state in which exhaust flows only to the turbocharger arrangement portion 110 and a second state in which exhaust flows to both the turbocharger arrangement portion 110 and the other turbocharger arrangement portion 120. The switching member 200 is, for example, configured with a switching valve. In this case, a state in which the switching valve is closed corresponds to the first state, and a state in which the switching valve is open corresponds to the second state.

When the switching member 200 is in the first state, the exhaust gas passes only through the turbocharger mounting section 110, which makes it easier for the exhaust gas to drift in the expansion section 140. The guide member 300 is a member that suppresses the occurrence of this drift. In other words, the guide member 300 is particularly effective when the switching member 200 is in the first state. However, the guide member 300 can also suppress the occurrence of drift when the switching member 200 is in the second state.

The guide member 300 is provided in the exhaust path 100. More specifically, the guide member 300 is disposed in the enlarged portion 140. The guide member 300 guides the exhaust toward the catalyst 5. The guide member 300 guides the exhaust in a direction along the center line AX (see FIG. 1) including the central axis of the enlarged portion 140, and in a direction toward the outside in a direction perpendicular to the center line AX. In other words, the guide member 300 guides the exhaust to a region of the catalyst 5 near the center line AX and to a region outside the center line AX in the direction perpendicular to the center line AX. As shown in FIG. 1 and FIG. 2, the guide member 300 has a first guide plate 310 and a second guide plate 320.

As shown by the arrow AR1 in FIG. 1, when the switching member 200 is in the first state, the first guide plate 310 guides the exhaust gas that has passed through the turbocharger mounting portion 110 toward an area R1 that is located on the opposite side of the catalyst 5 from the side where the turbocharger mounting portion 110 is located (the left side in FIG. 1) with respect to the center line AX.

As shown by the arrow AR2 in FIG. 1, when the switching member 200 is in the first state, the second guide plate 320 guides the exhaust gas that has passed through the turbocharger mounting portion 110 toward the region R2 that is located on the same side of the catalyst 5 as the turbocharger mounting portion 110 with respect to the center line AX (the right side in FIG. 1).

As shown in FIG. 1, the first guide plate 310 and the second guide plate 320 have a shape that gradually moves away from the center line AX toward the downstream side in the flow direction. The second guide plate 320 may have a protruding portion 322 that protrudes further upstream in the flow direction than the first guide plate 310.

As described above, in the exhaust pipe structure 10 of this embodiment, the guide member 300 is disposed in the expansion section 140 where exhaust drift is relatively likely to occur when the switching member 200 is in the first state, and guides the exhaust in a direction along the center line AX and in a direction toward the outside in the perpendicular direction, thereby suppressing the occurrence of exhaust drift in the expansion section 140. This suppresses the deterioration of the exhaust purification effect of the catalyst 5. In other words, the exhaust is effectively purified in the regions R1 and R2. In addition, the guide member 300 increases the flow speed of the exhaust toward the regions R1 and R2, suppressing the accumulation of deposits in those regions R1 and R2.

In the above embodiment, a so-called twin-turbo internal combustion engine system in which the exhaust path 100 has a turbocharger arrangement section 110 and another turbocharger arrangement section 120 is exemplified, but the exhaust pipe structure 10 in the above embodiment can also be applied to a so-called single-turbo internal combustion engine system, that is, a system in which the exhaust path 100 does not have another turbocharger arrangement section 120 and only has the turbocharger arrangement section 110.

The cross section of the guide member 300 in a plane perpendicular to the center line AX may be formed to be circular or elliptical.

[Aspects]
It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

An exhaust pipe structure according to one aspect of this disclosure includes an exhaust path through which exhaust from an internal combustion engine flows, and a guide member that is provided in the exhaust path and guides the exhaust toward a catalyst that purifies the exhaust. The exhaust path has a turbocharger arrangement section in which a turbocharger can be arranged, an enlarged section that is provided downstream of the turbocharger arrangement section in the exhaust flow direction and in which the flow passage area of the exhaust gradually increases toward the downstream in the exhaust flow direction, and a catalyst arrangement section that is connected to the downstream end of the enlarged section and in which the catalyst is arranged. The guide member is provided in the enlarged section and guides the exhaust in a direction along a center line that includes the central axis of the enlarged section and in a direction toward the outside in a direction perpendicular to the center line.

In this exhaust pipe structure, the guide member guides the exhaust gas in a direction along the center line that includes the central axis of the enlarged portion, and in a direction toward the outside in a direction perpendicular to the center line, thereby preventing the occurrence of biased exhaust flow. This prevents exhaust gas from stagnating in the catalyst placement portion or the enlarged portion, and the resulting accumulation of deposits near the stagnation, thereby preventing a decrease in the exhaust gas purification effect of the catalyst.

The exhaust pipe structure may further include a switching member provided in the exhaust path. In this case, the exhaust path may further include another turbocharger arrangement portion that is capable of arranging another turbocharger different from the turbocharger and is formed so as to be parallel to the turbocharger arrangement portion, and a junction portion that is formed downstream of the turbocharger arrangement portion and the other turbocharger arrangement portion and upstream of the enlarged portion and that joins the exhaust gas that has passed through the turbocharger arrangement portion and the exhaust gas that has passed through the other turbocharger arrangement portion, and the switching member is switchable between a first state in which the exhaust gas flows only through the turbocharger arrangement portion and a second state in which the exhaust gas flows through both the turbocharger arrangement portion and the other turbocharger arrangement portion.

The guide member may have a first guide plate that guides the exhaust gas that has passed through the turbocharger arrangement part toward the side opposite the turbocharger arrangement part with respect to the center line, and a second guide plate that guides the exhaust gas that has passed through the turbocharger arrangement part toward the same side as the turbocharger arrangement part with respect to the center line. In this case, it is preferable that the first guide plate and the second guide plate have a shape that gradually moves away from the center line toward the downstream side in the flow direction.

In this aspect, even when only one turbocharger is driven in a so-called twin-turbo internal combustion engine system equipped with two turbochargers (when the switching member is in the first state), the occurrence of bias in the exhaust gas that has passed through the turbocharger arrangement portion in the enlarged portion is effectively suppressed.

The second guide plate may also have a protruding portion that protrudes upstream in the flow direction from the first guide plate.

In this way, when the switching member is in the first state, the flow rate of the exhaust gas guided by the protruding portion of the second guide plate toward the catalyst located on the second guide plate side of the center line increases, so that the exhaust gas is guided toward the catalyst more uniformly. This further enhances the exhaust gas purification effect of the catalyst.

It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is indicated by the claims rather than the description of the embodiments above, and further includes all modifications within the meaning and scope of the claims.

1 internal combustion engine system, 2 internal combustion engine, 3 turbocharger (primary turbocharger), 4 other turbocharger (secondary turbocharger), 5 catalyst, 10 exhaust pipe structure, 100 exhaust path, 110 turbocharger arrangement section, 120 other turbocharger arrangement section, 130 junction section, 140 expansion section, 150 catalyst arrangement section, 200 switching member, 300 guide member, 310 first guide plate, 320 second guide plate.

Claims (1)

An exhaust path through which exhaust from the internal combustion engine flows;
A switching member provided in the exhaust path;
a guide member that is provided in the exhaust path and guides the exhaust gas toward a catalyst that purifies the exhaust gas,
The exhaust path is
a turbocharger mounting portion in which a turbocharger can be mounted;
Another turbocharger arrangement section in which another turbocharger different from the turbocharger can be arranged and which is formed in parallel with the turbocharger arrangement section;
an expansion section that is provided downstream of the turbocharger arrangement section in a flow direction of the exhaust gas, and in which a flow passage area of the exhaust gas gradually increases toward the downstream in the flow direction;
a junction section formed downstream of the turbocharger arrangement section and the other turbocharger arrangement section and upstream of the enlarged section, the junction section junctioning the exhaust gas that has passed through the turbocharger arrangement section and the exhaust gas that has passed through the other turbocharger arrangement section;
a catalyst placement section connected to a downstream end of the expansion section and in which the catalyst is placed;
the guide member is disposed in the expanded portion and guides the exhaust gas in a direction along a center line including a central axis of the expanded portion and in a direction toward an outside in a direction perpendicular to the center line ,
the switching member is switchable between a first state in which the exhaust gas flows only to the turbocharger mounting portion and a second state in which the exhaust gas flows to both the turbocharger mounting portion and the other turbocharger mounting portion,
The guide member is
a first guide plate that guides the exhaust gas that has passed through the turbocharger mounting portion toward an opposite side to a side on which the turbocharger mounting portion is located, with the center line as a reference;
a second guide plate that guides the exhaust gas that has passed through the turbocharger arrangement portion toward the same side as the turbocharger arrangement portion with respect to the center line,
the first guide plate and the second guide plate have a shape that gradually moves away from the center line toward a downstream side in the flow direction,
the second guide plate has a protruding portion that protrudes upstream in the flow direction relative to the first guide plate .

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