JP7287100B2 - Exhaust purification device - Google Patents

Description

The present invention relates to an exhaust purification device.

Patent Document 1 below describes an engine exhaust provided with a heat storage material made of a material having a melting point and a freezing point near a set temperature within the activation temperature range of the catalyst, upstream of the catalyst in the exhaust passage of the engine. A gas purifier is described.

Further, Patent Document 2 below discloses a catalyst case that houses a catalyst for purifying exhaust gas, and an exhaust heat recovery unit that recovers the heat of the exhaust gas passing through the catalyst and conducts heat transfer between the catalyst and the catalyst. A catalyst case device is described.

Further, in the following Patent Document 3, switching means for switching the flow of exhaust gas to a sub-flow path provided with a heat storage material is provided on the upstream side of the catalyst carrier in the exhaust pipe, and the switching means passes the exhaust gas through the sub-flow path and then in the exhaust pipe. A structure is described that allows exhaust gas to flow into the upstream side of the catalyst carrier.

JP-A-60-212608 JP-A-2000-179338 JP 2018-150915 A

However, none of the techniques described in Patent Documents 1 to 3 can switch between using and not using the reaction heat of the catalyst for purifying the exhaust gas to raise the temperature of the heat storage material, and there is room for improvement. There is

SUMMARY OF THE INVENTION It is an object of the present invention to provide an exhaust emission control system capable of switching between using and not using the reaction heat of a catalyst for purifying exhaust gas to raise the temperature of a heat storage member.

An exhaust purification device according to a first aspect includes a catalyst carrier provided in an exhaust pipe for carrying a catalyst for purifying exhaust gas, and a side stream through which exhaust gas flows, provided at a position adjacent to the catalyst carrier in the exhaust pipe. a heat storage member provided in the sub-flow path; exhaust gas is introduced from the exhaust pipe into the sub-flow path on the upstream side of the exhaust gas with respect to the catalyst carrier, and passes through the heat storage member; a first path that returns the exhaust gas from the secondary flow path to the exhaust pipe upstream of the catalyst carrier, and a first path that introduces the exhaust gas from the exhaust pipe into the secondary flow channel downstream of the catalyst carrier; a switching mechanism for switching between a second path through the heat storage member and returning the exhaust gas from the sub-path to the exhaust pipe on the downstream side of the exhaust gas relative to the catalyst carrier.

According to the exhaust purification device of the first aspect, the exhaust gas flowing through the exhaust pipe is purified by the catalyst carried on the catalyst carrier. A sub-flow path having a heat storage member is provided at a position adjacent to the catalyst carrier in the exhaust pipe, and the switching mechanism switches between the first and second paths to allow the exhaust gas to flow through the sub-flow path. be able to. In the first route, the exhaust is introduced from the exhaust pipe into the sub-flow path on the upstream side of the catalyst carrier and passes through the heat storage member, and the exhaust gas flows from the sub-flow channel on the upstream side of the catalyst carrier to the exhaust pipe. The exhaust is returned to Then, the exhaust gas returned to the exhaust pipe passes through the catalyst carrier. That is, in the first route, the reaction heat of the catalyst is not used to raise the temperature of the heat storage member. For example, by storing part of the heat of the exhaust in the heat storage member, the temperature of the exhaust is lowered. As a result, the temperature of the exhaust gas is lowered to such an extent that it does not reach a temperature that deteriorates the catalyst, thereby suppressing the deterioration of the catalyst and protecting the catalyst. Further, for example, when the temperature of the exhaust gas is low immediately after the engine is started, the temperature of the exhaust gas is raised by the heat storage member by introducing the exhaust gas into the secondary flow path through the first path.

Further, in the second route, the exhaust gas is introduced from the exhaust pipe into the sub-flow path downstream of the catalyst carrier, passes through the heat storage member, and is downstream of the catalyst support from the sub-flow channel. The exhaust is returned to the exhaust pipe. On the upstream side of the sub-flow path, reaction heat is generated when the exhaust gas in the exhaust pipe is purified by the catalyst carried on the catalyst carrier. Exhaust gas that has received the reaction heat of the catalyst passes through the heat storage member, and the reaction heat of the catalyst acts on the heat storage member due to the flow of the exhaust gas. That is, by utilizing the heat of reaction of the catalyst, heat can be stored in the heat storage member in a short period of time to raise the temperature, or the temperature of the heat storage member can be maintained above a predetermined level for a long period of time. Therefore, according to the above configuration, it is possible to switch between using the reaction heat of the catalyst for purifying the exhaust gas to raise the temperature of the heat storage member and not using it.

An exhaust purification device according to a second aspect is the exhaust purification device according to the first aspect, wherein a first connecting portion connecting the exhaust pipe and the sub-flow path upstream of the catalyst carrier in the exhaust gas; a second connection portion that connects the exhaust pipe and the sub-flow path downstream of the catalyst carrier, and the switching mechanism is provided in the first connection portion to switch the sub-flow path. A first position to close, and a first upstream communication port provided on the upstream side of the first connection portion while closing the exhaust pipe, and provided on the downstream side of the first connection portion. a first switching member that switches to a second position that opens the first downstream side communication port; a third position that is provided at the second connection portion and closes the secondary flow path; and a third position that closes the exhaust pipe. , a fourth position for opening a second upstream communication port provided on the upstream side of the second connection portion and opening a second downstream communication port provided on the downstream side of the second connection portion; and a second switching member that switches to

According to the exhaust purification device of the second aspect, the first switching member is provided at the first connecting portion on the upstream side of the exhaust gas from the catalyst carrier, and the first switching member is positioned between the first position and the second position. Position and switch. In the first position the first switching member closes the secondary flow path. At the second position, the first switching member closes the exhaust pipe, opens the first upstream communication port of the first connection portion, and opens the first downstream communication port of the first connection portion. Accordingly, by setting the first switching member to the first position, it is possible to realize a state in which the exhaust gas flows through the exhaust pipe. Further, by setting the first switching member to the second position, it is possible to realize a state in which the exhaust flows from the exhaust pipe to the sub-flow path upstream of the catalyst carrier.

A second switching member is provided at the second connecting portion on the downstream side of the exhaust gas relative to the catalyst carrier, and the second switching member is switched between the third position and the fourth position. In the third position the second switching member closes the secondary flow path. At the fourth position, the second switching member closes the exhaust pipe, opens the second upstream communication port of the second connection portion, and opens the second downstream communication port of the second connection portion. Accordingly, by setting the second switching member to the third position, it is possible to realize a state in which the exhaust gas flows into the exhaust pipe on the downstream side of the catalyst carrier. Further, by setting the second switching member to the fourth position, it is possible to realize a state in which exhaust gas flows from the exhaust pipe to the sub-flow path downstream of the catalyst carrier.

An exhaust gas purification device according to a third aspect is the exhaust gas purification device according to the second aspect, wherein the switching mechanism, with the first switching member in the second position, is connected to the exhaust gas through the first upstream communication port. Exhaust gas is introduced from the exhaust pipe into the sub-channel and is returned to the exhaust pipe from the sub-channel via the first downstream communication port, and the first switching member is configured to be the By setting the second position and setting the second switching member to the third position, the path is switched to the first path.

According to the exhaust purification device of the third aspect, by setting the first switching member to the second position, the exhaust gas is introduced from the exhaust pipe into the sub-flow path through the first upstream side communication port, and the first downstream side Exhaust gas is returned from the secondary flow path to the exhaust pipe via the side communication port. Further, the secondary flow path is closed by setting the second switching member to the third position. Thereby, the switching mechanism can be switched to the first path without complicating the configuration.

An exhaust gas purification device according to a fourth aspect is the exhaust gas purification device according to the second aspect or the third aspect, wherein the switching mechanism, with the second switching member at the fourth position, communicates with the second upstream side. exhaust gas is introduced from the exhaust pipe into the sub-channel through the port, and exhaust gas is returned from the sub-channel through the second downstream communication port to the exhaust pipe; By setting the switching member to the first position and setting the second switching member to the fourth position, the path is switched to the second path.

According to the exhaust purification device of the fourth aspect, by setting the second switching member to the fourth position, the exhaust gas is introduced from the exhaust pipe into the sub-flow path through the second upstream side communication port, and the second downstream side Exhaust gas is returned from the secondary flow path to the exhaust pipe via the side communication port. By setting the first switching member to the first position, the secondary flow path is closed. Thereby, the switching mechanism can be switched to the second path without complicating the configuration.

An exhaust purification device according to a fifth aspect is the exhaust purification device according to the second aspect, wherein when the engine is stopped, the first switching member is set to the second position, and the second switching member is set to the fourth position. By setting the position, the exhaust pipe in which the catalyst carrier is arranged is closed.

According to the exhaust gas purification device according to the fifth aspect, when the engine is stopped, the first switching member is set to the second position and the second switching member is set to the fourth position. As a result, the exhaust pipe in which the catalyst carrier is arranged is blocked, and the temperature drop of the catalyst carried by the catalyst carrier is suppressed when the engine is stopped.

An exhaust purification device according to a sixth aspect is the exhaust purification device according to any one of the second aspect to the fifth aspect, wherein the secondary flow path is the longitudinal direction of the exhaust pipe in which the catalyst carrier is arranged. It is arranged along the exhaust pipe on one side of the direction intersecting the direction.

According to the exhaust purification device of the sixth aspect, the sub flow path is arranged along the exhaust pipe on one side in the direction intersecting with the longitudinal direction of the exhaust pipe in which the catalyst carrier is arranged. Therefore, the temperature of the catalyst supported on the catalyst carrier is suppressed by keeping the catalyst carrier warm with the heat storage member provided in the sub-flow path.

An exhaust purification device according to a seventh aspect is the exhaust purification device according to the sixth aspect, wherein the heat storage member is a partition wall that partitions the inside of the sub-flow path along the longitudinal direction of the exhaust pipe, and the first first aspect is provided. The switching member is configured to contact one end of the heat storage member at the second position and close the exhaust pipe. A turn-back path of the sub-flow path is formed as the first path.

According to the exhaust purification device of the seventh aspect, the heat storage member is the partition wall that partitions the interior of the sub-flow path along the longitudinal direction of the exhaust pipe, and the first switching member is positioned at the second position at one end of the heat storage member. By contacting the part, the exhaust pipe is closed. Further, by arranging the second switching member at the third position, the heat storage member forms a turn-back path of the sub-flow path serving as the first path. Therefore, the switching mechanism can be switched to the first path with a simple configuration.

An exhaust gas purification device according to an eighth aspect is the exhaust gas purification device according to the sixth aspect or the seventh aspect, wherein the second switching member contacts the other end of the heat storage member at the fourth position, and the exhaust pipe By arranging the first switching member at the first position, the heat accumulating member forms a turn-back path of the secondary flow path that becomes the second path.

According to the exhaust purification device of the eighth aspect, the second switching member contacts the other end of the heat storage member at the fourth position, thereby closing the exhaust pipe. Further, by arranging the first switching member at the first position, the heat storage member forms a turn-back path of the sub-flow path serving as the second path. Therefore, the switching mechanism can be switched to the second path with a simple configuration.

An exhaust purification device according to a ninth aspect is the exhaust purification device according to any one of the second aspect to the fifth aspect, wherein the secondary flow path surrounds the exhaust pipe in which the catalyst carrier is arranged. are placed in

According to the exhaust purification device of the ninth aspect, the secondary flow path is arranged around the exhaust pipe in which the catalyst carrier is arranged. Therefore, the temperature of the catalyst supported on the catalyst carrier is suppressed by keeping the catalyst carrier warm with the heat storage member provided in the sub-flow path.

An exhaust purification device according to a tenth aspect is the exhaust purification device according to the ninth aspect, wherein the heat storage member is arranged around the exhaust pipe in which the catalyst carrier is arranged and extends inside the sub flow path. The first switching member is configured to be in contact with one end of the heat storage member at the second position to close the exhaust pipe, and the second switching member is the third switching member. By arranging at the position, the heat storage member forms a turn-back path of the sub-flow path serving as the first path.

According to the exhaust gas purification apparatus of the tenth aspect, the heat storage member is a cylindrical partition that is arranged around the exhaust pipe in which the catalyst carrier is arranged and partitions the inside of the sub-flow path. Therefore, the heat storage member disposed around the exhaust pipe keeps the catalyst carrier warm, thereby more reliably suppressing the temperature drop of the catalyst carried on the catalyst carrier. Further, the exhaust pipe is closed by the first switching member coming into contact with one end of the heat storage member at the second position. Further, by arranging the second switching member at the third position, the heat storage member forms a turn-back path of the sub-flow path serving as the first path. Therefore, the switching mechanism can be switched to the first path.

An exhaust purification device according to an eleventh aspect is the exhaust purification device according to the ninth aspect or the tenth aspect, wherein the second switching member contacts the other end of the heat storage member at the fourth position, and the exhaust pipe By arranging the first switching member at the first position, the heat accumulating member forms a turn-back path of the secondary flow path that becomes the second path.

According to the exhaust purification device of the eleventh aspect, the exhaust pipe is closed by the second switching member coming into contact with the other end of the heat storage member at the fourth position. Further, by arranging the first switching member at the first position, the heat storage member forms a turn-back path of the sub-flow path serving as the second path. Therefore, the switching mechanism can be switched to the second path.

An exhaust gas purification device according to a twelfth aspect is the exhaust gas purification device according to any one of the ninth aspect to the eleventh aspect, and is arranged outside the heat storage member along the circumferential direction of the heat storage member. In addition, the exhaust gas flows in one flow direction along the circumferential direction of the heat storage member, and the exhaust gas flows in the opposite flow direction along the circumferential direction of the heat storage member through the first opening on the downstream side in the flow direction of the exhaust gas. An outer partition plate is provided inside the heat storage member along the circumferential direction of the heat storage member, and the exhaust gas is flowed in one flow direction along the circumferential direction of the heat storage member. Furthermore, an inner partition plate is provided for causing the exhaust gas to flow in the opposite flow direction along the circumferential direction of the heat storage member through a second opening on the downstream side in the flow direction of the exhaust gas.

According to the exhaust emission purification device of the twelfth aspect, the outer partition plate is provided outside the heat storage member along the circumferential direction of the heat storage member. flow in one flow direction along the direction. Further, a first opening is provided in the outer partition plate on the downstream side in the flow direction of the exhaust gas, and the exhaust gas flows in the opposite flow direction along the circumferential direction of the heat storage member through the first opening. Further, inside the heat storage member, an inner partition plate is provided along the circumferential direction of the heat storage member. . Further, the inner partition plate is provided with a second opening downstream in the flow direction of the exhaust gas, and the exhaust gas flows in the opposite flow direction along the circumferential direction of the heat storage member through the second opening. Therefore, it is possible to increase the contact time between the exhaust gas and the heat storage member in the secondary flow path.

According to the exhaust purification device of the present invention, it is possible to switch between using the reaction heat of the catalyst for purifying the exhaust gas to raise the temperature of the heat storage material and not using it.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the exhaust gas purification device of 1st Embodiment. FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1 showing the exhaust gas purification device of the first embodiment; FIG. 4 is a cross-sectional view showing a state in which the exhaust purification device of the first embodiment is switched to a path through which the exhaust gas passes only through the catalyst carrier. FIG. 4 is a cross-sectional view showing a state in which exhaust gas is switched from a heat storage member to a path passing through a catalyst carrier in the exhaust purification device of the first embodiment; FIG. 2 is a cross-sectional view showing a state in which exhaust gas is switched from a catalyst carrier to a path passing through a heat storage member in the exhaust purification device of the first embodiment; FIG. 2 is a cross-sectional view showing a state when the engine is stopped in the exhaust purification system of the first embodiment; FIG. 4 is a diagram illustrating the positional relationship between the open state and the closed state of the switching valve in the switching state of the exhaust purification system of the first embodiment; It is a perspective view which shows the exhaust gas purification device of 2nd Embodiment. It is a perspective view which shows the exhaust gas purification device of 2nd Embodiment in the cross section along the axial direction. It is a perspective view showing the inside of the exhaust purification device of the second embodiment from which the outer cylinder is removed. It is a perspective view which shows the inside which removed the outer cylinder of the exhaust gas purification device of 2nd Embodiment in the cross section along the axial direction. It is a perspective view showing the vicinity of the cylinder portion of the exhaust purification device of the second embodiment. FIG. 7 is a cross-sectional view showing the vicinity of a heat storage member and a switching valve of an exhaust gas purification device of a second embodiment; FIG. 11 is a perspective view showing a tubular portion and a switching valve of an exhaust purification device of a second embodiment; FIG. 10 is a perspective view showing the outer flow path of the heat storage member in a state where the cylindrical portion of the exhaust purification device of the second embodiment is removed; FIG. 11 is a perspective view showing an inner flow path of a heat storage member of the exhaust purification device of the second embodiment;

An embodiment of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
An exhaust purification device 12 according to the first embodiment will be described below with reference to FIGS. 1 to 7. FIG.

As shown in FIGS. 1 and 2, the exhaust purification device 12 has a catalyst carrier 16 attached inside the exhaust pipe 14 . In this embodiment, the exhaust pipe 14 has a substantially cylindrical shape, but a portion in the longitudinal direction is a large-diameter pipe 14B having a larger diameter than the other portion, and the large-diameter pipe 14B is formed in a substantially U shape. (See Figure 2). The catalyst carrier 16 is arranged in the large-diameter pipe 14B.

In the following description, the terms "upstream side" and "downstream side" respectively refer to the upstream side and the downstream side in the flow direction of exhaust gas in the exhaust pipe 14 (arrow F1 direction).

In the exhaust pipe 14, the upstream portion of the large-diameter pipe 14B is a substantially cylindrical upstream pipe 14A, and the downstream portion thereof is a substantially cylindrical downstream pipe 14C. A portion from the upstream pipe 14A to the downstream pipe 14C via the large-diameter pipe 14B is a main flow path 22 through which the exhaust gas from the engine flows. The large-diameter pipe 14B and the upstream pipe 14A are connected by a tapered pipe 14D whose diameter gradually changes, and the large-diameter pipe 14B and the downstream pipe 14C are connected by a tapered pipe 14E whose diameter gradually changes. Contiguous.

The catalyst carrier 16 has a structure in which a surface area is increased by forming a thin plate into, for example, a honeycomb shape, and a catalyst is carried on this surface. The catalyst has the effect of purifying substances (hydrocarbons, etc.) in the exhaust gas flowing through the exhaust pipe 14 . Platinum, palladium, rhodium and the like can be given as examples of catalysts that exhibit such effects. The structure for increasing the surface area of the catalyst carrier 16 is not limited to the honeycomb shape described above, and may be a wavy shape or other shapes.

The catalyst carrier 16 is formed in a cylindrical shape as a whole so as to be accommodated inside the exhaust pipe 14 (see FIG. 2). Incidentally, the catalyst carrier 16 may be formed in a cylindrical shape.

On one side of the exhaust pipe 14 in a direction crossing the longitudinal direction (that is, the axial direction) of the large-diameter pipe 14B, a projecting portion 18 is provided that protrudes outward from the large-diameter pipe 14B. The projecting portion 18 is provided at a portion of the large-diameter pipe 14B of the exhaust pipe 14 in the circumferential direction. The projecting portion 18 is arranged along the exhaust pipe 14 . The upstream side and the downstream side of the projecting portion 18 of the large-diameter pipe 14B are substantially flat wall portions 15 . A radially inner end portion of the projecting portion 18 is connected to the wall portion 15 .

The projecting portion 18 is provided at a position adjacent to the catalyst carrier 16 . The projecting portion 18 is formed in a substantially rectangular parallelepiped shape, and extends in the tangential direction of the large-diameter pipe 14B in a cross section perpendicular to the axial direction of the exhaust pipe 14 shown in FIG.

More specifically, the projecting portion 18 includes an upstream wall portion 18A arranged in a direction substantially perpendicular to the axial direction of the large-diameter pipe 14B on the upstream side of the exhaust gas, and an upstream wall portion 18A arranged in a direction substantially perpendicular to the axial direction of the large-diameter pipe 14B on the exhaust downstream side. and a downstream wall portion 18B arranged in a direction substantially orthogonal to the direction (see FIG. 1). It also has a pair of side walls 18C and 18D arranged tangentially to the large-diameter pipe 14B (see FIG. 2). Furthermore, the projecting portion 18 connects the ends of the upstream wall portion 18A, the downstream wall portion 18B, and the pair of side wall portions 18C and 18D and is arranged along the large-diameter pipe 14B. A portion 18E is provided.

A secondary flow path 20 through which the exhaust gas flows is formed inside the projecting portion 18 . A sealing portion 21 that covers a part of the peripheral surface of the catalyst carrier 16 is provided between the secondary flow path 20 and the catalyst carrier 16 inside the projecting portion 18 . The seal portion 21 constitutes a boundary portion between the projecting portion 18 and the large-diameter pipe 14B (see FIG. 2). A seal surface 21A of the seal portion 21 on the side of the sub-channel 20 is substantially planar. In this embodiment, the seal portion 21 is composed of a vacuum heat insulating portion, but may be composed of other members.

A heat storage member 24 is arranged along the axial direction of the exhaust pipe 14 in the secondary flow path 20 of the projecting portion 18 . The heat storage member 24 spans the pair of side wall portions 18C and 18D. In other words, the heat storage member 24 is a partition wall that partitions the interior of the sub-flow path 20 along the axial direction of the exhaust pipe 14 . The heat storage member 24 is separated from the upstream wall portion 18A and the downstream wall portion 18B. That is, a gap for exhaust gas is formed between the heat storage member 24 and the upstream wall portion 18A, and a gap for exhaust gas is formed between the heat storage member 24 and the downstream wall portion 18B. It is

Although illustration is omitted, the heat storage member 24 includes a housing member in which a plurality of fins are arranged in a direction intersecting with the plate-shaped portion arranged along the axial direction of the exhaust pipe 14 . The heat storage member 24 is configured such that a heat storage material is housed inside the housing member. The accommodation member is provided with a plurality of fins to increase its substantial surface area. The heat storage member 24 is a heat exchanger that exchanges heat with the outside with respect to the heat storage material inside. That is, heat is exchanged between the exhaust gas flowing through the sub-flow path 20 and the heat storage material in the storage member of the heat storage member 24 . For example, when the temperature of the exhaust gas flowing through the secondary flow path 20 is higher than that of the heat storage material of the heat storage member 24, the heat of the exhaust gas moves to the heat storage material and is stored in the heat storage material, thereby decreasing the temperature of the exhaust gas. Conversely, if the exhaust gas flowing through the sub-flow path 20 has a lower temperature than the heat storage material of the heat storage member 24, the heat of the heat storage material is transferred to the exhaust gas, and the temperature of the exhaust gas rises.

The exhaust purification device 12 includes an upstream connection portion 26 that connects the exhaust pipe 14 and the sub-channel 20 upstream of the catalyst carrier 16 and an exhaust pipe downstream of the catalyst carrier 16. A downstream connecting portion 28 is provided to connect the channel 14 and the secondary channel. The exhaust purification device 12 is provided with a switching mechanism 30 for switching the exhaust flow path. The switching mechanism 30 includes an upstream switching valve 32 provided at the upstream connection portion 26 and a downstream switching valve 34 provided at the downstream connection portion 28 . The upstream connection portion 26 is an example of a first connection portion, and the downstream connection portion 28 is an example of a second connection portion. The upstream switching valve 32 is an example of a first switching member, and the downstream switching valve 34 is an example of a second switching member.

The upstream switching valve 32 includes a shaft 32A orthogonal to the flow direction of the exhaust gas, a valve body 32B extending from the shaft 32A in one direction and having a short length, and a valve body 32C extending in the other direction from the shaft 32A and having a long length. , is equipped with The upstream switching valve 32 has valve bodies 32B and 32C that rotate around a shaft 32A. The valve body 32B has a substantially rectangular shape when viewed in the axial direction of the exhaust pipe 14 and is shaped to contact the upstream end portion 24A of the heat storage member 24 . Further, the valve body 32C is substantially U-shaped when viewed in the axial direction of the exhaust pipe 14, and is shaped to contact the inner wall surface of the large-diameter pipe 14B. The upstream end 24A is an example of one end.

The rotational position of the upstream switching valve 32 is controlled by the controller 40 . The upstream switching valve 32 can take an open state KS1 indicated by a solid line and a closed state HS1 indicated by a two-dot chain line in FIG. 1 depending on the rotational positions of the valve bodies 32B and 32C.

When the upstream switching valve 32 is in the open state KS1, the valve body 32B contacts the seal surface 21A of the seal portion 21, and the valve body 32C contacts the inner surface of the wall portion 15. As shown in FIG. As a result, the upstream connection portion 26 of the sub-flow path 20 is closed, and the exhaust gas flows to the large-diameter pipe 14B and passes through the catalyst carrier 16 . Here, the open state KS1 of the upstream switching valve 32 is an example of the first position.

When the upstream switching valve 32 is in the closed state HS1, the valve body 32B contacts the upstream end 24A of the heat storage member 24, and the valve body 32C contacts the inner wall surface of the large-diameter pipe 14B. As a result, the large-diameter pipe 14B of the exhaust pipe 14 is closed, the upstream communication port 36A arranged on the upstream side of the upstream connection portion 26 is opened, and the downstream side of the upstream connection portion 26 arranged on the downstream side is opened. The communication port 36B is opened. Here, the upstream communication port 36A is an example of a first upstream communication port, and the downstream communication port 36B is an example of a first downstream communication port. As a result, on the upstream side of the catalyst carrier 16, the exhaust gas is introduced into the secondary flow path 20 via the upstream communication port 36A. The closed state HS1 of the upstream switching valve 32 is an example of the second position.

The downstream switching valve 34 is formed symmetrically with the upstream switching valve 32 in the cross-sectional view shown in FIG. The downstream switching valve 34 includes a shaft 34A, a valve body 34B, and a valve body 34C. The downstream switching valve 34 has valve bodies 34B and 34C that rotate around a shaft 34A.

The rotational position of the downstream switching valve 34 is controlled by the controller 40 . The downstream switching valve 34 can take a closed state HS2 indicated by a solid line and an open state KS2 indicated by a two-dot chain line in FIG. 1 depending on the rotational positions of the valve bodies 34B and 34C.

When the downstream switching valve 34 is in the open state KS<b>2 , the valve body 34</b>B contacts the seal surface 21</b>A of the seal portion 21 and the valve body 34</b>C contacts the inner surface of the wall portion 15 . As a result, the downstream connection portion 28 of the sub-flow path 20 is closed, and the exhaust gas flows through the large-diameter pipe 14B of the exhaust pipe 14 . Here, the open state KS2 of the downstream switching valve 34 is an example of the third position.

When the downstream switching valve 34 is in the closed state HS2, the valve body 34B contacts the downstream end 24B of the heat storage member 24, and the valve body 34C contacts the inner wall surface of the large-diameter pipe 14B. As a result, the large-diameter pipe 14B of the exhaust pipe 14 is closed, the upstream communication port 38A arranged on the upstream side of the downstream connection portion 28 is opened, and the downstream side of the upstream connection portion 26 arranged on the downstream side is opened. The communication port 38B is opened. Here, the upstream communication port 36A is an example of a second upstream communication port, and the downstream communication port 38B is an example of a second downstream communication port. As a result, on the downstream side of the catalyst carrier 16, the exhaust gas is introduced into the secondary flow path 20 via the upstream communication port 38A. The closed state HS2 of the downstream switching valve 34 is an example of the fourth position. Also, the downstream end 24B is an example of the other end.

An engine operation sensor 42 is connected to the control device 40 to detect the operation and stop of the engine. Note that the control device 40 may also be configured to control the state of the engine, in which case the control device also serves as an engine operation sensor.

The exhaust purification device 12 is provided with an exhaust temperature sensor 44 , a heat storage member temperature sensor 46 and a catalyst carrier temperature sensor 48 .

The exhaust temperature sensor 44 is provided on the upstream pipe 14A side of the exhaust pipe 14 , detects the temperature of the exhaust gas, and transmits the detected temperature to the control device 40 .

The heat storage member temperature sensor 46 is arranged in contact with the heat storage member 24 , detects the temperature of the heat storage member 24 , and transmits the detected temperature to the control device 40 .

A catalyst carrier temperature sensor 48 is arranged in contact with the catalyst carrier 16 to detect the temperature of the catalyst carrier 16 and transmit it to the controller 40 . Since the temperature of the catalyst carrier is substantially equal to the temperature of the catalyst, the temperature detected by the catalyst carrier temperature sensor 48 will be simply the catalyst temperature hereinafter.

The control device 40 controls the upstream switching valve 32 and the downstream switching valve 34 based on the exhaust temperature, the heat storage member temperature and the catalyst temperature in addition to the operation of the engine. In the exhaust purification device 12, the flow path is switched between four flow paths (see FIGS. 3 to 6), which will be described later, depending on the rotational positions of the upstream switching valve 32 and the downstream switching valve 34 of the switching mechanism 30. FIG.

Next, the operation and effects of this embodiment will be described.

First, the four flow paths (see FIGS. 3 to 6) that are switched by the switching mechanism 30 will be described.

As shown in FIG. 3, when the upstream switching valve 32 is in the open state KS1 (that is, the first position) and the downstream switching valve 34 is in the open state KS2 (that is, the third position), the exhaust is indicated by an arrow F3. Thus, the exhaust gas flows through the large-diameter pipe 14B of the exhaust pipe 14 without being introduced into the sub-flow path 20, and passes through the catalyst carrier 16. As shown in FIG. That is, the exhaust passes only through the catalyst carrier 16 without passing through the heat storage member 24 of the sub-flow path 20 . As a result, the exhaust gas is purified by the catalyst supported on the catalyst support 16, and the purified exhaust gas flows further downstream from the downstream pipe 14C. In such a channel, for example, compared to a structure in which the exhaust flows through the sub-channel 20, the heat of the exhaust acts on the catalyst to raise the temperature of the catalyst in a short time (improve the rate of temperature increase). is possible.

As shown in FIG. 4, when the upstream switching valve 32 is in the closed state HS1 (that is, the second position) and the downstream switching valve 34 is in the open state KS2 (that is, the third position), the exhaust is directed to the arrow F4. As shown, it is introduced into the sub-channel 20 via the upstream communication port 36A of the upstream connection portion 26 . In this state, the downstream switching valve 34 closes the downstream connecting portion 28 , so that the heat storage member 24 forms a turn-back path of the sub-flow path 20 serving as the first path. As a result, the exhaust gas flows from the outside to the inside of the heat storage member 24 along the secondary flow path 20 as indicated by the arrow F4. It is introduced into 14 large-diameter pipes 14B. The exhaust then passes through the catalyst carrier 16 . That is, in FIG. 4 , the exhaust purification device 12 switches the first route through which the exhaust passes through the catalyst support 16 after passing through the heat storage member 24 of the sub-flow path 20 (passing around the heat storage member 24). .

In the exhaust purification device 12, the switching mechanism 30 can be switched to the first path without complicating the configuration. Part of the heat of the exhaust gas is stored in the heat storage member 24 of the sub-channel 20 in the first channel. Then, the exhaust gas whose temperature has been lowered is introduced into the large-diameter pipe 14B of the exhaust pipe 14 and passes through the catalyst carrier 16 . Since the temperature of the exhaust gas is lowered, for example, the heat of the high-temperature exhaust gas does not act on the catalyst supported on the catalyst support 16, and deterioration of the catalyst can be suppressed.

As shown in FIG. 5, when the upstream switching valve 32 is in the open state KS1 (that is, the first position) and the downstream switching valve 34 is in the closed state HS2 (that is, the fourth position), the exhaust is directed to the exhaust pipe 14. of catalyst support 16 . After that, the exhaust gas is introduced into the secondary flow path 20 via the upstream communication port 38A of the downstream connection portion 28 as indicated by an arrow F5. In this state, the upstream switching valve 32 closes the upstream connection portion 26 , so that the heat storage member 24 forms a turn-back path of the sub-flow path 20 serving as the second path. As a result, the exhaust gas flows along the secondary flow path 20 from the inside to the outside of the heat storage member 24 as indicated by the arrow F5, and the exhaust gas flows through the downstream communication port 38B of the downstream connection portion 28 to the exhaust pipe. Introduced in 14. That is, in FIG. 5 , the exhaust emission control device 12 is switched to the second route through the heat storage member 24 in the secondary flow path 20 (passing around the heat storage member 24) after the exhaust gas passes through the catalyst carrier 16. .

In the exhaust purification device 12, the switching mechanism 30 can be switched to the second path without complicating the configuration. In the second channel, the temperature of the exhaust gas is raised by reaction heat generated by the catalyst of the catalyst carrier 16 , so part of the heat of the exhaust gas is stored in the heat storage member 24 of the secondary channel 20 . As a result, compared to the case where the heat of reaction generated by the catalyst is not applied to the heat storage member 24, the heat is stored in the heat storage member 24 in a short time to raise the temperature, or the temperature of the heat storage member 24 is kept above a predetermined temperature for a long time. can be maintained.

As shown in FIG. 6, for example, when the engine is stopped, the upstream switching valve 32 is closed HS1 (ie, second position), and the downstream switching valve 34 is closed HS2 (ie, fourth position). As a result, the large-diameter pipe 14B of the exhaust pipe 14 in which the catalyst carrier 16 is arranged is blocked by the upstream switching valve 32 and the downstream switching valve 34 . As a result, even when the engine is stopped and the exhaust gas is not introduced into the catalyst carrier 16, the catalyst carried on the catalyst carrier 16 can be kept warm, and the temperature drop of the catalyst can be suppressed.

Therefore, in the exhaust purification device 12, it is possible to switch between using the reaction heat of the catalyst for purifying the exhaust gas to raise the temperature of the heat storage member and not using it. Further, the sub-flow path 20 is arranged along the large-diameter pipe 14B on one side in a direction crossing the longitudinal direction (that is, the axial direction) of the large-diameter pipe 14B in which the catalyst carrier 16 is arranged. Therefore, the temperature of the catalyst supported on the catalyst carrier 16 is suppressed by keeping the catalyst carrier 16 warm by the heat storage member 24 provided in the sub-flow path 20 .

Next, an example of control of the upstream switching valve 32 and the downstream switching valve 34 of the switching mechanism 30 will be described in detail.

In this control, threshold temperatures are set for the exhaust temperature, the heat storage member temperature, and the catalyst temperature, and opening and closing of the upstream switching valve 32 and the downstream switching valve 34 are controlled in relation to these threshold temperatures. In Table 1, each of the exhaust temperature, the heat storage member temperature, and the catalyst temperature is "high" when it is higher than the set threshold temperature, and "low" when it is lower than the set threshold temperature. This threshold temperature is a catalyst activation temperature, and if the temperature is higher than this threshold temperature, the catalyst exhibits a high ability to purify exhaust gas.

Further, in Table 1, as shown in FIG. 7, when the upstream switching valve 32 is arranged in the horizontal direction (that is, when the large-diameter pipe 14B of the exhaust pipe 14 shown in FIG. 1 is open), A state in which the upstream switching valve 32 is arranged in the vertical direction (that is, a case in which the large-diameter pipe 14B of the exhaust pipe 14 shown in FIG. 1 is closed) is defined as a closed state. Similarly, when the downstream switching valve 34 is arranged in the horizontal direction (that is, when the large-diameter pipe 14B of the exhaust pipe 14 shown in FIG. 1 is open), it is opened, and the downstream switching valve 34 is in the vertical direction. (ie, when the large-diameter pipe 14B of the exhaust pipe 14 shown in FIG. 1 is closed) is defined as a closed state.

Condition (1) in Table 1 is a state in which the engine is stopped. In this case, as shown in FIG. 6, both the upstream switching valve 32 and the downstream switching valve 34 are closed. Inflow of low-temperature air into the upstream pipe 14A and the downstream pipe 14C is suppressed, and convection between the heat storage member 24 and the catalyst carrier 16 is also suppressed. Then, the heat stored in the heat storage member 24 is radiated and acts on the catalyst carrier 16 , thereby suppressing the temperature drop of the catalyst carrier 16 .

Condition (2) is when the engine is running and all of the exhaust temperature, the catalyst temperature, and the heat storage member temperature are lower than the threshold temperature. In this case, if the exhaust gas temperature is higher than the heat storage member temperature, both the upstream switching valve 32 and the downstream switching valve 34 are opened. In this case, since the exhaust gas is introduced into the catalyst carrier 16, the temperature of the catalyst carrier 16 can be raised in a short time. However, when the exhaust gas temperature is lower than the heat storage member temperature, the upstream switching valve 32 is closed and the downstream switching valve 34 is opened. As a result, the exhaust gas is not introduced into the catalyst carrier 16 and is heated in the secondary flow path 20 by receiving the heat of the heat storage member 24 . Since the heated exhaust gas is introduced into the catalyst carrier 16, the temperature of the catalyst carrier 16 can be raised. That is, if the temperature of the exhaust gas is higher than that of the heat storage member 24, the exhaust gas is introduced into the catalyst carrier 16. If the temperature of the heat storage member 24 is higher than that of the exhaust gas, the temperature of the exhaust gas is raised by the heat storage member 24 before 16.

Condition (3) is when the engine is operating, the exhaust temperature and the catalyst temperature are lower than the threshold temperature, and the heat storage member temperature is higher than the threshold temperature. In this case, the upstream switching valve 32 is closed, the downstream switching valve 34 is open, and the exhaust gas flows into the secondary flow path 20 . The temperature of the exhaust gas is raised by the heat storage member 24, and the heated exhaust gas is introduced into the catalyst carrier 16, so that the temperature of the catalyst carrier 16 can be raised in a short time. Therefore, it is possible to suppress the temperature drop of the catalyst due to the introduction of the low-temperature exhaust gas into the catalyst carrier 16 .

Condition (4) is when the engine is operating, the exhaust temperature and the heat storage member temperature are lower than the threshold temperature, and the catalyst temperature is higher than the threshold temperature. In this case, if the exhaust gas temperature is higher than the heat storage member temperature, the upstream switching valve 32 is opened, the downstream switching valve 34 is closed, and the exhaust gas is introduced into the catalyst carrier 16 . Exhaust gas having a relatively higher temperature than the heat storage member 24 is introduced into the catalyst carrier 16 without being lowered in temperature by the heat storage member 24, thereby suppressing the temperature drop of the catalyst. On the other hand, when the exhaust gas temperature is lower than the heat storage member temperature, the upstream switching valve 32 is closed and the downstream switching valve 34 is opened. The exhaust gas is not introduced into the catalyst carrier 16 and is heated by the heat of the heat storage member 24 in the secondary flow path 20 . Since the exhaust gas whose temperature has been raised is introduced into the catalyst carrier 16 , the temperature drop of the catalyst carrier 16 can be suppressed compared to the case where the temperature of the exhaust gas is not raised by the heat storage member 24 .

Condition (5) is when the engine is operating, the exhaust temperature is lower than the threshold temperature, and the catalyst temperature and the heat storage member temperature are higher than the threshold temperature. In this case, if the catalyst temperature is higher than the heat storage member temperature, the upstream switching valve 32 is opened and the downstream switching valve 34 is closed. Since the exhaust gas is introduced into the catalyst carrier 16, excessive temperature rise of the catalyst can be suppressed. That is, the catalyst carrier 16 is cooled by the exhaust gas. On the other hand, when the catalyst temperature is lower than the heat storage member temperature, the upstream switching valve 32 is closed and the downstream switching valve 34 is opened. In the secondary flow path 20, the exhaust gas whose temperature has been raised by the heat storage member 24 is introduced into the catalyst carrier 16, so that the temperature of the catalyst carrier 16 can be raised. However, it should be operated within the range not exceeding the heat resistance temperature of the catalyst.

Condition (6) is when the engine is running and all of the exhaust temperature, the catalyst temperature, and the heat storage member temperature are higher than the threshold temperature. In this case, if the catalyst temperature is higher than the exhaust temperature and the exhaust temperature is higher than the heat storage member temperature, the upstream switching valve 32 is closed and the downstream switching valve 34 is opened. Exhaust gas whose temperature has been lowered by the heat storage member 24 is introduced into the catalyst carrier 16, and excessive temperature rise of the catalyst can be suppressed. Further, when the catalyst temperature is higher than the heat storage member temperature and the heat storage member temperature is higher than the exhaust temperature, the upstream switching valve 32 is opened and the downstream switching valve 34 is closed. Excessive temperature rise can be suppressed. That is, the catalyst carrier 16 is cooled by the exhaust gas. When the heat storage member temperature is higher than the exhaust temperature and the exhaust temperature is higher than the catalyst temperature, the upstream switching valve 32 is opened and the downstream switching valve 34 is closed. 16 to raise the temperature of the catalyst. When the exhaust gas temperature is higher than the heat storage member temperature and the heat storage member temperature is higher than the catalyst temperature, the upstream switching valve 32 is closed and the downstream switching valve 34 is opened. By introducing the exhaust gas whose temperature has been raised by the heat storage member 24 into the catalyst carrier 16, the temperature of the catalyst can be raised. However, these are operated within a range that does not exceed the heat resistance temperature of the catalyst.

Condition (7) is when the engine is operating, the exhaust temperature is higher than the threshold temperature, and the catalyst temperature and the heat storage member temperature are lower than the threshold temperature. In this case, the upstream switching valve 32 is opened and the downstream switching valve 34 is closed. By introducing the exhaust gas into the catalyst carrier 16, the temperature of the catalyst can be raised.

Condition (8) is when the engine is operating, the exhaust temperature and the heat storage member temperature are higher than the threshold temperature, and the catalyst temperature is lower than the threshold temperature. In this case, when the exhaust gas temperature is lower than the heat storage member temperature, the upstream switching valve 32 is closed and the downstream switching valve 34 is opened. The exhaust gas is not introduced into the catalyst carrier 16 and is heated by the heat of the heat storage member 24 in the secondary flow path 20 . Since the exhaust gas whose temperature has been raised is introduced into the catalyst carrier 16 , the temperature rise of the catalyst carrier 16 can be accelerated compared to the case where the temperature of the exhaust gas is not raised by the heat storage member 24 . On the other hand, if the exhaust gas temperature is higher than the heat storage member temperature, the upstream switching valve 32 is opened and the downstream switching valve 34 is closed. Exhaust gas having a relatively higher temperature than the heat storage member 24 is introduced into the catalyst carrier 16 without being lowered in temperature by the heat storage member 24, thereby suppressing the temperature drop of the catalyst.

Condition (9) is when the engine is operating, the exhaust temperature and the catalyst temperature are higher than the threshold temperature, and the heat storage member temperature is lower than the threshold temperature. In this case, if the exhaust temperature is higher than the catalyst temperature, the upstream switching valve 32 is closed and the downstream switching valve 34 is opened. Exhaust gas whose temperature has been lowered by the heat storage member 24 is introduced into the catalyst carrier 16, and excessive temperature rise of the catalyst can be suppressed. When the catalyst temperature is higher than the exhaust temperature, the upstream switching valve 32 is opened and the downstream switching valve 34 is closed. Since the exhaust gas is introduced into the catalyst carrier 16 without being lowered in temperature by the heat storage member 24, the temperature drop of the catalyst can be suppressed.

In the exhaust purification device 12, the temperature of the catalyst can be appropriately controlled by controlling the upstream switching valve 32 and the downstream switching valve 34 based on the exhaust gas temperature, the heat storage member temperature, and the catalyst temperature according to the control shown in Table 1.

[Second embodiment]
Next, an exhaust purification system of a second embodiment will be described with reference to FIGS. 8 to 16. FIG. In addition, about the same component part as 1st Embodiment mentioned above, the same number is attached and the description is abbreviate|omitted.

As shown in FIGS. 8 and 9, in the exhaust purification device 72, the predetermined range including the upstream side and the downstream side of the large-diameter pipe 74A in which the catalyst carrier 16 is arranged in the exhaust pipe 74 is larger than the large-diameter pipe 74A. It is covered with an outer cylinder 76 having a large diameter. The outer cylinder 76 has a cylindrical shape surrounding the large-diameter pipe 74A in the circumferential direction.

An upstream end portion 76A of the outer cylinder 76 is connected to the upstream pipe 14A of the exhaust pipe 74 by an upstream tapered portion 76B whose diameter gradually decreases toward the upstream side. A large-diameter pipe 76C connected to the upstream tapered portion 76B is provided in the intermediate portion of the outer cylinder 76 . The large-diameter pipe 76C is connected to a downstream taper portion 76D whose diameter gradually decreases downstream, and the downstream end portion 76E of the outer cylinder 76 is connected to the downstream pipe 14C by the downstream taper portion 76D.

As shown in FIGS. 9 to 11, inside the large-diameter pipe 76C of the outer cylinder 76, a substantially cylindrical tubular portion 78 is provided in contact with the large-diameter pipe 76C. A flow path guide 80 is provided on the upstream side of the cylindrical portion 78 and extends from a portion of the cylindrical portion 78 in the circumferential direction. A flow path guide 82 is provided extending from the portion. The flow path guide 80 and the flow path guide 82 are symmetrical when viewed from a direction perpendicular to the axial direction of the tubular portion 78 .

The flow path guide 80 has a box shape that is open on the side of the large-diameter pipe 74A. More specifically, the flow path guide 80 includes a curved portion 80A that is continuous with the cylindrical portion 78, an upstream wall portion 80B that extends radially inward from the upstream end of the curved portion 80A, and a circumferential and a pair of side wall portions 80C arranged on both sides and connected to the upstream wall portion 80B. In addition, in FIG. 10 and the like, the side wall portion 82C on the far side is not illustrated.

Similar to the flow path guide 80, the flow path guide 82 has a box-like shape with the side of the large-diameter pipe 74A open, and includes a curved portion 82A, a downstream wall portion 82B, and a pair of side wall portions 82C. ing. In addition, in FIG. 10 and the like, the side wall portion 82C on the far side is not illustrated.

A secondary flow path 84 is formed inside the cylindrical portion 78, the flow path guide 80, and the flow path guide 82 and outside the large-diameter pipe 74A. A heat storage member 86 is arranged in the sub-flow path 84 . The heat storage member 86 is formed in a tubular shape and arranged between the large-diameter pipe 74A and the tubular portion 78 . That is, the heat storage member 86 is separated from the large-diameter pipe 74B and the outer cylinder 76 . In other words, the heat storage member 86 is arranged around the large-diameter pipe 74A in which the catalyst carrier 16 is arranged, and is a cylindrical partition wall that partitions the inside of the sub-flow path 84 .

Inside the flow path guide 80 , an upstream connection portion 90 is provided that connects the exhaust pipe 74 and the sub-flow path 84 upstream of the catalyst carrier 16 with respect to the exhaust gas. Inside the flow path guide 82 , a downstream connection portion 92 is provided that connects the exhaust pipe 74 and the sub-flow path 84 downstream of the catalyst carrier 16 in the exhaust. The exhaust purification device 72 is provided with a switching mechanism 94 that switches the exhaust flow path. The switching mechanism 94 includes an upstream switching valve 96 provided at the upstream connection portion 90 and a downstream switching valve 98 provided at the downstream connection portion 92 . The upstream connection portion 90 is an example of a first connection portion, and the downstream connection portion 92 is an example of a second connection portion. Also, the upstream switching valve 96 is an example of a first switching member, and the downstream switching valve 98 is an example of a second switching member.

The upstream switching valve 96 includes a shaft 96A perpendicular to the flow direction of the exhaust gas, a small valve body 96B extending from the shaft 96A on one side, and a large valve body 96C extending from the shaft 96A to the other side. , is equipped with The upstream switching valve 96 has valve bodies 96B and 96C that rotate around a shaft 96A. When viewed in the axial direction of the exhaust pipe 14, the outer shape of the valve body 96B and the valve body 96C is formed in a substantially disk shape.

The rotational position of the upstream switching valve 96 is controlled by a controller (not shown). The upstream switching valve 96 can take a closed state HS1 (see FIGS. 9 to 11) and an open state KS1 (see FIG. 12) depending on the rotational positions of the valve bodies 96B and 96C.

A substantially planar seal portion 100A is provided on the upstream side of the catalyst carrier 16 and contacts the valve body 96B when the upstream switching valve 96 is in the open state KS1. When the upstream switching valve 96 is in the open state KS1, the valve body 96B contacts the seal portion 100A and the valve body 96C contacts the upstream wall portion 80B of the flow path guide 80. As shown in FIG. As a result, the upstream connection portion 90 of the sub-flow path 84 is closed, and the exhaust gas flows to the large-diameter pipe 74A and passes through the catalyst carrier 16 . Here, the open state KS1 of the upstream switching valve 96 is an example of the first position.

When the upstream switching valve 96 is in the closed state HS1, the valve bodies 96B and 96C are in contact with the upstream end portion 86A of the heat storage member 86. As shown in FIG. As a result, the exhaust pipe 74 is closed, the upstream communication port 102A arranged on the upstream side of the upstream connection portion 90 is opened, and the downstream communication port 102B arranged on the downstream side of the upstream connection portion 90 is opened. (See FIG. 13). Here, the upstream communication port 102A is an example of a first upstream communication port, and the downstream communication port 102B is an example of a first downstream communication port. As a result, on the upstream side of the catalyst carrier 16, the exhaust gas is introduced into the secondary flow path 84 via the upstream communication port 102A. The closed state HS1 of the upstream switching valve 96 is an example of the second position.

The downstream switching valve 98 is formed symmetrically with the upstream switching valve 96 in the cross-sectional view shown in FIG. The downstream switching valve 98 includes a shaft 98A, a valve body 98B, and a valve body 98C. The downstream switching valve 98 has valve bodies 98B and 98C that rotate around a shaft 98A.

The rotational position of the downstream switching valve 98 is controlled by a controller (not shown). The downstream switching valve 98 can take a closed state HS2 (not shown) and an open state KS2 (see FIGS. 9 to 13) depending on the rotational positions of the valve bodies 98B and 98C.

A substantially planar seal portion 100B is provided on the downstream side of the catalyst carrier 16 and contacts the valve body 96B when the downstream switching valve 98 is in the open state KS2. When the downstream switching valve 98 is in the open state KS2, the valve body 98B contacts the seal portion 100B, and the valve body 98C contacts the downstream wall portion 82B of the flow path guide 82 (see FIG. 13). As a result, the downstream connection portion 92 of the secondary flow path 84 is closed, and the exhaust flows through the exhaust pipe 74 . Here, the open state KS2 of the downstream switching valve 98 is an example of the third position.

Although not shown, when the downstream switching valve 98 is in the closed state HS2, the valve bodies 98B and 98C contact the downstream end 86B of the heat storage member 86. As shown in FIG. As a result, the exhaust pipe 74 is closed, the upstream communication port 104A arranged on the upstream side of the downstream connection portion 92 is opened, and the downstream communication port 104B arranged on the downstream side of the downstream connection portion 92 is opened. be done. Here, the upstream communication port 104A is an example of a second upstream communication port, and the downstream communication port 104B is an example of a second downstream communication port. As a result, on the downstream side of the catalyst carrier 16, the exhaust gas is introduced into the secondary flow path 84 via the upstream communication port 104A. The closed state HS2 of the downstream switching valve 98 is an example of the fourth position.

The secondary flow path 84 is provided with an upstream wall portion 110 arranged along the circumferential direction of the tubular portion 78 at the upstream end portion of the inner peripheral surface of the tubular portion 78 . A radially inner end of the upstream wall portion 110 contacts the outer surface of the heat storage member 86 . Further, the secondary flow path 84 is provided with a downstream wall portion 112 arranged along the circumferential direction of the tubular portion 78 at the downstream end portion of the inner peripheral surface of the tubular portion 78 . The radially inner end of the downstream wall portion 112 contacts the outer surface of the heat storage member 86 .

In addition, an outer partition plate 114 is provided at an intermediate portion of the inner peripheral surface of the cylindrical portion 78 and is arranged along the circumferential direction of the cylindrical portion 78 and the heat accumulating member 86 outside the heat accumulating member 86 (FIGS. 11 and 12). 13 and 15). The outer partition plate 114 is in contact with the outer surface of the heat storage member 86 . A vertical wall portion 116 arranged along the axial direction of the tubular portion 78 is provided on the inner peripheral surface of the tubular portion 78 (see FIG. 15). One end of the outer partition plate 114 in the circumferential direction of the tubular portion 78 is connected to the vertical wall portion 116 . The other end of the outer partition plate 114 in the circumferential direction of the tubular portion 78 is separated from the vertical wall portion 116 , and an opening 118 is provided between the outer partition plate 114 and the vertical wall portion 116 . Opening 118 is an example of a first opening.

The upstream end of the vertical wall portion 116 is connected to the upstream wall portion 110, and the downstream end of the vertical wall portion 116 is connected to the downstream wall portion 112 (see FIG. 15). At a position adjacent to the vertical wall portion 116 in the upstream wall portion 110 , an upstream opening 120 is provided on the side opposite to the opening 118 with the vertical wall portion 116 interposed therebetween. A downstream opening 122 is provided at a position adjacent to the vertical wall portion 116 in the downstream wall portion 112 on the side opposite to the opening 118 with the vertical wall portion 116 interposed therebetween.

Further, the secondary flow path 84 is provided with an upstream wall portion 130 arranged along the circumferential direction of the large-diameter pipe 74A at the upstream end of the outer peripheral surface of the large-diameter pipe 74A. A radially outer end of the upstream wall portion 130 contacts the inner surface of the heat storage member 86 . Further, the secondary flow path 84 is provided with a downstream wall portion 132 arranged along the circumferential direction of the large-diameter pipe 74A at the downstream end portion of the outer peripheral surface of the large-diameter pipe 74A. A radially outer end of the downstream wall portion 132 contacts the inner surface of the heat storage member 86 .

In addition, an inner partition plate 134 is provided inside the heat storage member 86 along the circumferential direction of the large diameter pipe 74A and the heat storage member 86 at an intermediate portion of the outer peripheral surface of the large diameter pipe 74A (see FIG. 11). , see FIGS. 13 and 16). The inner partition plate 134 is in contact with the inner surface of the heat storage member 86 . A vertical wall portion 136 arranged along the axial direction of the large-diameter pipe 74A is provided on the outer peripheral surface of the large-diameter pipe 74A (see FIG. 16). One end of the inner partition plate 134 in the circumferential direction of the large-diameter pipe 74A is connected to the vertical wall portion 136 . The other end of the inner partition plate 134 in the circumferential direction of the large-diameter pipe 74A is separated from the vertical wall portion 136, and an opening 138 is provided between the inner partition plate 134 and the vertical wall portion 136. Opening 138 is an example of a second opening. A wall portion 140 is provided on the upstream side and the downstream side of the vertical wall portion 136 so as to face the opening 138 and block the heat storage member 86 . Further, an upstream opening 142 and a downstream opening 144 are provided on the side opposite to the wall portion 140 on the upstream side and the downstream side of the vertical wall portion 136 .

Next, the operation and effects of this embodiment will be described.

As shown in FIG. 9, when the upstream switching valve 96 is in the closed state HS1 (that is, the second position) and the downstream switching valve 98 is in the open state KS2 (that is, the third position), the exhaust is connected to the upstream side. It is introduced into the secondary channel 84 via the upstream communication port 102A of the portion 90 . In this state, the downstream switching valve 98 closes the downstream connection portion 92 , so that the heat storage member 86 and the flow path guide 82 form a turn-back path of the secondary flow path 84 serving as the first path.

As shown in FIG. 15, the exhaust gas introduced into the sub-flow path 84 through the upstream communication port 102A of the upstream connecting portion 90 flows from the upstream opening 120 of the upstream wall portion 110 to the upstream wall as indicated by an arrow F11. The exhaust gas is introduced between the portion 110 and the outer partition plate 114, and flows in one flow direction along the circumferential direction outside the heat storage member 86 as indicated by the arrow F12. Further, as indicated by arrow F12, the exhaust gas is introduced from the opening 118 at the position of the vertical wall portion 116 between the outer partition plate 114 and the downstream wall portion 112, and flows backward along the outer side of the heat storage member 86 in the circumferential direction. flows in the direction of flow. Then, the exhaust gas flows from the downstream opening 122 of the downstream wall portion 112 to the rear side of the downstream wall portion 112 at the position of the vertical wall portion 116, as indicated by arrow F13.

Further, as shown in FIG. 16, exhaust gas is introduced between the inner partition plate 134 and the downstream wall portion 132 from the downstream opening 144 inside the heat storage member 86 as indicated by an arrow F14. Then, as indicated by an arrow F14, the exhaust gas flows outside the heat storage member 86 in one flow direction along the circumferential direction. Furthermore, as indicated by arrow F15, the exhaust gas is introduced between the inner partition plate 134 and the upstream wall portion 130 from the opening 138 at the position of the vertical wall portion 136, and flows backward along the inner side of the heat storage member 86 in the circumferential direction. flows in the direction of flow. Then, the exhaust gas flows inside the heat storage member 86 from the upstream opening 142 to the front side of the upstream wall portion 130 as indicated by an arrow F16.

Further, the exhaust gas is introduced into the large-diameter pipe 74A of the exhaust pipe 74 via the downstream communication port 102B of the upstream connection portion 90 (see FIG. 13), and passes through the catalyst carrier 16. That is, in FIG. 9 , the exhaust emission control device 72 is switched to the first route through which the exhaust gas passes through the catalyst carrier 16 after passing around the heat storage member 86 in the secondary flow channel 84 .

Although not shown, when the upstream switching valve 96 is in the open state KS1 (that is, the first position) and the downstream switching valve 98 is in the closed state HS2 (that is, the fourth position), the exhaust is directed to the exhaust pipe 74. It passes through the catalyst carrier 16 of the large-diameter pipe 74A. Then, the exhaust gas is introduced into the secondary flow path 84 via the upstream communication port 104A of the downstream connection portion 92 . In this state, the upstream switching valve 96 closes the upstream connection portion 90 , so that the heat storage member 86 and the flow path guide 80 form a turn-back path of the sub-flow path 84 serving as the second path. Exhaust gas introduced into the secondary flow path 84 through the upstream communication port 104A of the downstream connection portion 92 flows in a direction opposite to the flow direction of the exhaust gas shown in FIGS. 15 and 16 . Exhaust gas is then introduced into the exhaust pipe 14 via the downstream communication port 104B of the downstream connection portion 92 . That is, in the above state, the exhaust emission control device 72 is switched to the second path in which the exhaust passes around the heat storage member 86 in the secondary flow path 84 after passing through the catalyst carrier 16 .

The upstream switching valve 96 and the downstream switching valve 98 of the switching mechanism 94 can be controlled in the same manner as Table 1 of the first embodiment, for example.

Therefore, in the exhaust purification device 72, it is possible to switch between using the reaction heat of the exhaust purification catalyst for raising the temperature of the heat storage member and not using it. Further, in the exhaust purification device 72, the heat storage member 86 is arranged around the large-diameter pipe 74A of the exhaust pipe 14 in which the catalyst carrier 16 is arranged, and is a cylindrical partition wall that partitions the inside of the sub-channel 84. It is Therefore, the catalyst carrier 16 is kept warm by the heat storage member 86, so that the temperature drop of the catalyst carried by the catalyst carrier 16 is more reliably suppressed. In addition, in the exhaust purification device 72, the exhaust gas flows along the circumferential direction of the heat storage member 86 inside and outside the heat storage member 86, so that the contact time between the exhaust gas and the heat storage member 86 can be increased in the secondary flow path 84. .

In the exhaust purification devices 12 and 72 of the above-described embodiments, the heat storage material is not particularly limited as long as it can receive and store heat from high-temperature exhaust gas and can dissipate heat to low-temperature exhaust gas. For example, a molten salt having a melting point in the range of 100° C. or higher and 600° C. or lower can be used. Molten salt is a substance that melts salts and oxides that are solid at room temperature to liquid by heating, and is composed of cations and anions. Then, the enthalpy changes with the phase change (melting, primary transition, or secondary transition) to store and release heat.

As can be seen from Table 2 above, the phase change during actual heat storage and heat dissipation in each of the above embodiments may be melting accompanied by a phase transition between a solid phase and a liquid phase, and during the phase change, the heat storage material Heat is stored and released as latent heat. Alternatively, heat may be stored and released by a phase change that does not involve a phase transition between a solid phase and a liquid phase.

Among these molten salts, a molten salt having a phase change temperature in the range of 100° C. or higher and 600° C. or lower can efficiently perform heat exchange with the exhaust gas, and is preferable for the exhaust gas purifier of each embodiment and modification. Applicable.

Note that, depending on the type of molten salt, there is also a molten salt that undergoes a volume change due to a phase change. In the case of using a molten salt whose volume changes, the storage member of the heat storage member should have a sufficient capacity to absorb the volume change of the molten salt.

In the second embodiment, the outer partition plate 114 and the inner partition plate 134 are arranged along the circumferential direction of the heat storage member 86, but the present invention is not limited to this configuration. For example, a spiral outer partition plate is provided outside the cylindrical heat storage member so that the exhaust gas flows spirally outside the heat storage member, and a spiral inner partition plate is provided inside the cylindrical heat storage member to allow the exhaust air to flow. You may make it flow spirally inside a heat-storage member.

Although the present invention has been described in detail with respect to particular embodiments, it should be understood that the invention is not limited to such embodiments and that various other embodiments are possible within the scope of the invention. clear to the trader.

12 Exhaust purification device 14 Exhaust pipe 16 Catalyst carrier 18 Protruding portion 20 Secondary flow path 24 Heat storage member 24A Upstream end (an example of one end)
24B downstream end (an example of the other end)
26 upstream connection (an example of the first connection)
28 downstream connection (an example of a second connection)
30 switching mechanism 32 upstream switching valve (an example of a first switching member)
34 downstream switching valve (an example of a second switching member)
36A upstream communication port (an example of the first upstream communication port)
36B downstream communication port (an example of the first downstream communication port)
38A upstream communication port (an example of a second upstream communication port)
38B downstream communication port (an example of a second downstream communication port)
72 Exhaust purification device 74 Exhaust pipe 84 Secondary flow path 86 Heat storage member 86A Upstream end (an example of one end)
86B downstream end (an example of the other end)
90 upstream connection part (an example of the first connection part)
92 downstream connection (an example of a second connection)
94 switching mechanism 96 upstream switching valve (an example of a first switching member)
98 downstream switching valve (an example of a second switching member)
102A upstream communication port (an example of a first upstream communication port)
102B downstream communication port (an example of a first downstream communication port)
104A upstream communication port (an example of a second upstream communication port)
104B downstream communication port (an example of a second downstream communication port)
114 outer partition plate 118 opening (an example of a first opening)
134 inner partition plate 138 opening (an example of a second opening)

Claims (11)

a catalyst carrier that is provided in the exhaust pipe and carries a catalyst that purifies exhaust gas;
a secondary flow path provided adjacent to the catalyst carrier in the exhaust pipe, through which exhaust gas flows;
a heat storage member provided in the sub-channel;
Exhaust gas is introduced from the exhaust pipe into the secondary flow path on the upstream side of the exhaust gas from the catalyst carrier and passes through the heat storage member, and from the secondary flow channel on the upstream side of the exhaust gas from the catalyst carrier. a first route for returning exhaust gas to an exhaust pipe; introducing exhaust gas from the exhaust pipe into the sub-flow channel downstream of the catalyst carrier, passing through the heat storage member, and further from the catalyst carrier; a switching mechanism for switching to a second path for returning the exhaust gas from the secondary flow path to the exhaust pipe on the downstream side of the exhaust gas;
a first connecting portion that connects the exhaust pipe and the sub-flow path upstream of the catalyst carrier;
a second connecting portion that connects the exhaust pipe and the sub-flow path downstream of the catalyst carrier;
has
The switching mechanism is
A first position provided in the first connecting portion for closing the secondary flow path, and a first upstream communication port provided on the upstream side of the first connecting portion while closing the exhaust pipe and opening the and a second position for opening a first downstream communication port provided on the downstream side of the first connection portion;
A third position provided in the second connection portion for closing the secondary flow path, and a second upstream communication port provided on the upstream side of the second connection portion while closing the exhaust pipe. and a fourth position for opening the second downstream side communication port provided downstream in the second connection portion;
Exhaust gas purification device. The switching mechanism introduces exhaust gas from the exhaust pipe into the secondary flow path through the first upstream communication port in a state where the first switching member is in the second position, and the first downstream side exhaust gas is returned from the secondary flow path to the exhaust pipe through the communication port,
2. The exhaust purification device according to claim 1 , wherein switching to the first path is performed by setting the first switching member to the second position and setting the second switching member to the third position. The switching mechanism introduces exhaust gas from the exhaust pipe into the sub-flow path through the second upstream side communication port in a state where the second switching member is in the fourth position, and the second downstream side exhaust gas is returned from the secondary flow path to the exhaust pipe through the communication port,
3. The exhaust purification device according to claim 1 , wherein switching to the second path is performed by setting the first switching member to the first position and setting the second switching member to the fourth position. When the engine is stopped, the first switching member is set to the second position and the second switching member is set to the fourth position, thereby closing the exhaust pipe in which the catalyst carrier is arranged. The exhaust purification device according to claim 1 . 5. The secondary flow path is arranged along the exhaust pipe on one side in a direction crossing the longitudinal direction of the exhaust pipe in which the catalyst carrier is arranged. 1. The exhaust purification device according to item 1. The heat storage member is a partition wall that partitions the interior of the secondary flow path along the longitudinal direction of the exhaust pipe,
The first switching member is configured to contact one end of the heat storage member at the second position to close the exhaust pipe,
6. The exhaust gas purification device according to claim 5 , wherein the second switching member is arranged at the third position so that the heat storage member forms a turn-back path of the sub-flow path serving as the first path. The second switching member is configured to contact the other end of the heat storage member at the fourth position to close the exhaust pipe,
7. The exhaust gas purification system according to claim 5 , wherein the first switching member is arranged at the first position, so that the heat storage member forms a turn-back path of the sub-flow path serving as the second path. Device. 5. The exhaust purification device according to any one of claims 1 to 4 , wherein the sub-flow path is arranged around the exhaust pipe in which the catalyst carrier is arranged. The heat storage member is a cylindrical partition that is arranged around the exhaust pipe in which the catalyst carrier is arranged and that partitions the inside of the secondary flow path,
The first switching member is configured to contact one end of the heat storage member at the second position to close the exhaust pipe,
9. The exhaust purification device according to claim 8 , wherein the second switching member is arranged at the third position, so that the heat storage member forms a turn-back path of the sub-flow path serving as the first path. The second switching member is configured to contact the other end of the heat storage member at the fourth position to close the exhaust pipe,
10. The exhaust purification system according to claim 8 , wherein the first switching member is arranged at the first position, so that the heat storage member forms a turn-back path of the secondary flow path serving as the second path. Device. Outside the heat storage member, the exhaust gas is arranged along the circumferential direction of the heat storage member, the exhaust gas flows in one flow direction along the circumferential direction of the heat storage member, and a first flow direction downstream side of the exhaust gas flow direction an outer partition plate is provided for causing the exhaust gas to flow in the opposite flow direction along the circumferential direction of the heat storage member through the opening,
Inside the heat storage member, the exhaust gas is arranged along the circumferential direction of the heat storage member, the exhaust gas flows in one flow direction along the circumferential direction of the heat storage member, and a second flow direction downstream side of the exhaust gas flows. 11. The exhaust purification device according to any one of claims 8 to 10 , further comprising an inner partition plate that allows the exhaust gas to flow in a direction opposite to the circumferential direction of the heat storage member through the opening.

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