JP7017479B2 - engine - Google Patents

Description

The present invention relates to an engine, and more particularly to an engine in which catalyst activation is promoted.

Conventionally, there are an engine equipped with an exhaust manifold, an exhaust lead-out path derived from the manifold outlet of the exhaust manifold, a catalyst case provided in the exhaust lead-out path, and a catalyst housed in the catalyst case (for example, Patent Document 1). reference).

JP-A-2010-185340 (see FIGS. 1, 4, and 6)

<< Problem >> The catalyst is difficult to activate.
In the engine of Patent Document 1, the catalyst is located far from the combustion chamber, the temperature of the exhaust gas flowing out of the combustion chamber drops by the time it reaches the catalyst, and the catalyst is difficult to activate.

An object of the present invention is to provide an engine in which activation of a catalyst is promoted.

In the present invention, an exhaust port and a catalyst arranged in the exhaust port are provided, and the catalyst is formed to be thin and has a thickness dimension in the central axis direction shorter than a radial dimension, and is provided downstream of the exhaust gas of the catalyst. It is equipped with an exhaust gas recirculation device, an EGR cooler, and a pair of bypass water channels that are individually branched from the main water channel that cools the engine body. The exhaust gas recirculation device and the EGR cooler are individually connected to the pair of bypass water channels. ing.
In addition, an exhaust temperature sensor arranged between the catalyst and the exhaust throttle device and a control device for linking the exhaust temperature sensor and the exhaust throttle device are provided, and the control device is based on the exhaust temperature detected by the exhaust temperature sensor. , It is configured to adjust the opening degree of the exhaust throttle device.
It is desirable that the catalyst is formed in a circular shape when viewed in a direction parallel to its central axis.

The present invention has the following effects.
The catalyst is arranged in the exhaust port near the combustion chamber, and the temperature of the exhaust discharged from the combustion chamber does not easily decrease by the time it reaches the catalyst, and the activation of the catalyst is promoted.
In addition, the thin catalyst has a small volume, and activation of the catalyst by raising the temperature is promoted.
Further, although the thin catalyst is arranged in the exhaust port having a narrow passage cross-sectional area, the passage resistance of the exhaust is small and the increase in the back pressure is suppressed.
The increase in back pressure due to the throttle of the exhaust throttle device raises the temperature of the exhaust gas, the temperature of the catalyst, and promotes the incineration of unburned deposits adhering to the exhaust inlet of the catalyst and the activation of the catalyst.
The resistance of each of the pair of bypass channels to which the exhaust throttle device and the EGR cooler are individually connected is small, the amount of bypass cooling water supplied to the exhaust throttle device is large, the temperature of the exhaust throttle device drops, and the exhaust throttle device Thermal deterioration is suppressed.
The resistance of each channel of the pair of bypass channels is small, the amount of bypass cooling water supplied to the EGR cooler increases, the temperature of the EGR gas decreases, the density of the EGR gas increases, and the EGR rate increases.
In addition, the exhaust temperature sensor that directly detects the temperature of the exhaust on the upstream side of the exhaust throttle device can quickly detect the rise in the temperature of the exhaust on the upstream side of the exhaust throttle device, and the opening degree of the exhaust throttle device can be increased. Control delay is unlikely to occur, the exhaust temperature does not rise too much, and thermal deterioration of the exhaust throttle device is suppressed.

It is a schematic diagram of the engine explaining the exhaust system of the engine which concerns on 1st Embodiment of this invention. 2A and 2B are explanatory views of a basic example and a modified example of the arrangement of the catalyst and the catalyst, FIG. 2A is an explanatory view of the basic example of the arrangement of the catalyst and the catalyst, and FIG. 2B is FIG. 2A. BB line cross-sectional view, FIG. 2C is an explanatory view of a modified example of the catalyst, FIG. 2D is an explanatory diagram of a modified example of the arrangement of the catalyst, and FIG. 2E is a deformation of the arrangement of the exhaust temperature sensor. It is explanatory drawing of the example (reference example) . It is a schematic diagram explaining the water cooling system of the engine of FIG. It is a flowchart explaining the control of the clogging clearing mode of the engine of FIG. It is a flowchart explaining the control of the DPF regeneration mode of the engine of FIG. It is a schematic diagram explaining the water cooling system of the engine which concerns on 2nd Embodiment of this invention.

1 to 5 are diagrams for explaining the engine according to the first embodiment of the present invention, and FIG. 6 is a diagram for explaining the engine according to the second embodiment of the present invention.
In each embodiment, a vertical water-cooled in-line multi-cylinder diesel engine is used.

The engine according to the first embodiment of the present invention will be described.
As shown in FIG. 1, the engine includes a cylinder block (20a) and a cylinder head (20b) attached to the top of the cylinder block (20a). A cooling water pump (25) and a pacing transmission case (15) are assembled to the front part of the cylinder block (20a) with the erection direction of the crank shaft (14) in the front-rear direction, one in front and the other in rear. There is. An engine cooling fan (16) is attached to the pump input shaft of the cooling water pump (25), and the cooling water pump (25) and the engine cooling fan (16) are connected to the crank shaft (14) via a fan belt (17). Driven by. A radiator (26) is arranged in front of the engine cooling fan (16). At the rear of the cylinder block (20a), a flywheel (14a) attached to the rear end of the crank shaft (14) is arranged.

As shown in FIG. 1, the exhaust manifold (1) is assembled on one side of the cylinder head (20b) with the width direction of the engine as the lateral direction, and the exhaust lead path is taken from the manifold outlet (1a) of the exhaust manifold (1). (2) has been derived. The exhaust derivation path (2) is a turbine outlet cylinder (6b) derived from the turbocharger (6) and the turbine housing (6a) accommodating the turbine of the supercharger (6), which are arranged in order from the exhaust upstream side. ), The exhaust throttle device (8), the exhaust relay pipe (7), and the exhaust purification case (18), and the exhaust (5) flowing out from the manifold outlet (1a) of the exhaust manifold (1) is supercharged. It is discharged through the turbine housing (6a) of the machine (6), the turbine outlet cylinder (6b), the exhaust throttle device (8), the exhaust relay pipe (7), and the exhaust purification case (18) in this order.

As shown in FIG. 1, an intake manifold (30) is assembled on the other side of the cylinder head (20b), and a supercharger is installed at the manifold inlet (30a) of the intake manifold (30) via a supercharging pipe (31). The compressor outlet (6d) of the compressor housing (6c) of (6) is connected, the air cleaner (33) is connected to the compressor inlet (6e) via the airflow sensor case (32), and the air (34) is connected to the air (34). It is supercharged to the intake manifold (30) via the air cleaner (33), the compressor housing (6c) of the supercharger (6), the supercharging pipe (31), and the manifold inlet (30a) in this order.

As shown in FIG. 1, the EGR gas derivation path (19) is derived from the exhaust manifold (1), and the EGR gas derivation path (19) consists of the EGR cooler (23) and the EGR valve device (EGR valve device) in order from the lead-out upstream side. 27), the outlet end of the EGR gas recirculation path (19) is connected to the manifold inlet (30a) of the intake manifold (30), and a part of the exhaust gas separated from the exhaust gas (5) of the exhaust gas recirculation (1) is , EGR gas (23a) is supplied to the intake manifold (30) via the EGR cooler (23) and the EGR valve device (27) in this order.

This engine includes a fuel injection valve (35) of a common rail type combustion injection device and a control device (10) for controlling the opening of the fuel injection valve (35), and the control device (10) is a predetermined sensor. The fuel injection timing and injection amount from the fuel injection valve (35) are set based on the detected engine target rotation speed, engine actual rotation speed, engine load, intake amount, and intake temperature.
An engine ECU is used in the control device (10). The ECU is an abbreviation for an electronic control unit and is a microcomputer.

As shown in FIGS. 2A to 2D, the catalysts (4) provided with the exhaust ports (5a) to (5d) and the catalysts (4) arranged in the exhaust ports (5a) to (5d) are provided, and the catalyst (4) is provided. Is formed to be thin in which the thickness dimension in the central axis (4c) direction is shorter than the radial dimension.
Therefore, the catalyst (4) is arranged in the exhaust ports (5a) to (5d) near the combustion chamber, and the temperature of the exhaust (5) flowing out of the combustion chamber is unlikely to drop until it reaches the catalyst (4). , Activation of the catalyst (4) is promoted.
Further, the thin catalyst (4) has a small volume, and activation of the catalyst (4) is promoted by raising the temperature.
Further, although the thin catalyst (4) is arranged in the exhaust ports (5a) to (5d) having a narrow passage cross-sectional area, the passage resistance of the exhaust (5) is small and the back pressure rises. It is suppressed.

The catalyst (4) on the upstream side of the exhaust of the exhaust throttle device (8) is a catalyst for purifying the exhaust gas and raising the temperature of the exhaust gas by purifying the harmful components in the exhaust gas (5) and burning the unburned fuel with the catalyst.
DOC is used for the catalyst (4). DOC is an abbreviation for diesel oxidation catalyst. The DOC is a flow-through honeycomb type in which a large number of cells along the axial length direction are arranged side by side in a penetrating manner. The DOC has an oxidation catalyst component supported in the cell. In DOC, HC (hydrocarbon) and CO (carbon monoxide) in the exhaust gas (5) are oxidized to H ₂ O (water) and CO ₂ . Further, in the DOC, the unburned fuel supplied in the exhaust gas (5) is catalytically burned, the temperature of the exhaust gas (5) rises, and the DPF (12) arranged downstream is regenerated. When the catalyst downstream side catalyst (13) is used instead of the DPF (12), its temperature rises and activation is achieved.

DPF is an abbreviation for diesel particulate filter and captures PM contained in the exhaust gas (5). PM is an abbreviation for particulate matter.
The DPF (12) is a wall-flow honeycomb type in which a large number of cells along the axial length direction are arranged side by side inside, and the exhaust inlets (12a) and exhaust outlets (12b) of adjacent cells are alternately sealed. be.

An SCR catalyst or a _NOX storage reduction catalyst can be used as the catalyst (4) on the upstream side of the exhaust of the exhaust throttle device (8).
The SCR catalyst is an abbreviation for Selective Catalytic Reduction type catalyst, and a flow-through honeycomb type catalyst in which a large number of cells along the axial length are arranged side by side in a penetrating manner is used, and the exhaust upstream thereof. A urea water injector is placed on the side, and ammonia gas is obtained at high temperature by injecting urea water into the exhaust gas, and NOx (nitrogen oxide) is reduced by this ammonia to N ₂ (nitrogen gas) and H ₂ Obtain O (water vapor).
The NO _X storage reduction catalyst is a catalyst that temporarily stores NO _X in the exhaust gas and then reduces (converts to N ₂ ).

As shown in FIGS. 2A and 2C, the catalyst (4) is formed in a circular shape when viewed in a direction parallel to its central axis (4c).
Since the catalyst (4) is formed in a circle point-symmetrical with respect to its central axis (4c), deterioration of the catalyst component of the catalyst (4) is unlikely to occur.

In the modified example of the catalyst (4) of FIG. 2C, the catalyst (4) has a central through hole (4d) and is formed in an annular shape when viewed in a direction parallel to the central axis (4c). ..
The central through hole (4d) reduces the volume of the catalyst (4) and promotes the activation of the catalyst (4) by raising the temperature.
Further, although the catalyst (4) having the central through hole (4d) is arranged in the exhaust ports (5a) to (5d) having a narrow passage cross-sectional area, the passage resistance of the exhaust (5) is the center. It is reduced by the through hole (4d), and the increase in back pressure is suppressed.
In the basic example shown in FIG. 2B, a single catalyst (4) is arranged at each exhaust outlet of each exhaust port (5a) to (5d), whereas in the modified example shown in FIG. 2D, the single catalyst (4) is arranged. A pair of catalysts (4) are arranged in series in the passing direction of the exhaust (5) of each exhaust port (5a) to (5d), but three or more catalysts (4) may be arranged in series. In this modification, the catalyst (4) may be provided with a central through hole (4d).

As shown in FIG. 1, an exhaust throttle device (8) provided downstream of the exhaust of the catalyst (4) is provided.
Therefore, the temperature of the exhaust (5) rises due to the increase of the back pressure due to the throttle of the exhaust throttle device (8), the temperature of the catalyst (4) rises, and the catalyst (4) adheres to the exhaust inlet (4a). The incineration of unburned deposits and the activation of the catalyst (4) are promoted.

The unburned deposit adhering to the exhaust inlet (4a) of the catalyst (4) is a mixture of unburned fuel and PM of the main injection fuel, and when the engine load is small and the exhaust temperature is low, the catalyst (4) It easily accumulates in the exhaust port (4a) of the catalyst (4) and clogs it.

As shown in FIG. 1, an exhaust temperature sensor (9) arranged between the catalyst (4) and the exhaust throttle device (8), and a control device for linking the exhaust temperature sensor (9) and the exhaust throttle device (8). (10) is provided, and the control device (10) is configured to adjust the opening degree of the exhaust throttle device (8) based on the temperature of the exhaust (5) detected by the exhaust temperature sensor (9). There is.
In this case, the engine has the following advantages:
The exhaust temperature sensor (9) that directly detects the temperature of the exhaust gas (5) on the upstream side of the exhaust gas throttle device (8) promptly raises the temperature of the exhaust gas (5) on the upstream side of the exhaust gas throttle device (8). It can be detected, the control delay of the opening degree of the exhaust throttle device (8) is unlikely to occur, the temperature of the exhaust (5) does not rise too much, and the thermal deterioration of the exhaust throttle device (8) is suppressed.

As shown in FIG. 2 (E), the exhaust temperature sensor (9) arranged at the position closest to the exhaust downstream side of the exhaust throttle device (8), the exhaust temperature sensor (9), and the exhaust throttle device (8) are linked. The control device (10) is provided, and the control device (10) is configured to adjust the opening degree of the exhaust throttle device (8) based on the temperature of the exhaust (5) detected by the exhaust temperature sensor (9). It may have been. The arrangement of the exhaust temperature sensor (9) is a reference example not included in the embodiment.
In this case, the temperature of the exhaust gas (5) on the upstream side of the exhaust gas throttle device (8) is measured by the exhaust temperature sensor (9) that detects the temperature of the exhaust gas (5) at the position closest to the exhaust gas downstream side of the exhaust gas throttle device (8). The rise can be detected quickly, the control delay of the opening degree of the exhaust throttle device (8) is unlikely to occur, the temperature of the exhaust (5) does not rise too much, and the thermal deterioration of the exhaust throttle device (8) is suppressed. ..
The separation distance from the exhaust throttle device (8) to the exhaust temperature sensor (9) is sufficiently shorter than the separation distance from the exhaust throttle device (8) to the catalyst (11) on the downstream side of the throttle, and the former is half of the latter. It is preferably less than one, and more preferably less than one-third of the latter.

As shown in FIG. 1, a catalyst (11) on the downstream side of the throttle is provided downstream of the exhaust throttle device (8), and the control device (10) is an exhaust gas (5) detected by the exhaust temperature sensor (9). ), The temperature of the exhaust (5) on the exhaust inlet (11a) side of the catalyst (11) on the downstream side of the exhaust throttle device (8) is estimated, and the temperature of the exhaust (5) is estimated. Therefore, it is configured to control the exhaust gas treatment using the catalyst (11) on the downstream side of the throttle.
Therefore, the exhaust temperature sensor (9) used for controlling the exhaust throttle device (8) is also used for controlling the exhaust treatment using the throttle downstream side catalyst (11), and the number of exhaust temperature sensors is reduced.

The same catalyst as the catalyst (4) on the upstream side of the throttle can be used for the catalyst (11) on the downstream side of the throttle. The same DOC as that of the catalyst (4) on the upstream side of the throttle is used for the catalyst (11) on the downstream side of the throttle.

As shown in FIG. 1, the exhaust gas treatment using the throttle downstream side catalyst (11) involves an exhaust gas temperature rise treatment in which the unburned fuel supplied in the exhaust gas (5) is catalytically burned by the throttle downstream side catalyst (11). ..
Therefore, when the DPF (12) is arranged on the downstream side of the throttle downstream side catalyst (11), the DPF (12) can be regenerated by the exhaust gas temperature raising process.
When the catalyst downstream side catalyst (13) is arranged on the downstream side of the throttle downstream side catalyst (11) instead of the DPF (12), the catalyst downstream side catalyst (13) can be activated by the exhaust gas temperature raising treatment. It becomes.

The throttle downstream side catalyst (11) and DPF (12) are housed in the exhaust purification case (18), the throttle downstream side catalyst (11) is arranged on the exhaust upstream side, and the DPF (12) is arranged on the exhaust downstream side. ing.
When the catalyst downstream side catalyst (13) is used instead of the DPF (12), the catalyst downstream side catalyst (13) is arranged on the exhaust downstream side of the throttle downstream side catalyst (11).
A catalyst similar to that of the catalyst (4) on the upstream side of the throttle can be used for the catalyst (11) on the downstream side of the throttle. It is desirable to use the same DOC as the catalyst (4) on the upstream side of the throttle for the catalyst (11) on the downstream side of the throttle.
As the catalyst downstream side catalyst (13), an SCR catalyst, a _NOX storage reduction catalyst, or the like can be used instead of the DOC.
When an SCR catalyst is used for the throttle downstream side catalyst (11), it is desirable to use DOC for the catalyst downstream side catalyst (13) to purify the ammonia that has passed through the SCR catalyst.

The configuration of the water cooling device is as follows.
As shown in FIG. 3, a main water channel (21) for cooling the engine body (20) and a bypass water channel (22) branched from the main water channel (21) are provided, and an exhaust throttle device (8) is provided in the bypass water channel (22). ) Is connected.
This engine has the following advantages:
The exhaust throttle device (8) heated by the exhaust (5) is water-cooled, the temperature of the exhaust throttle device (8) is lowered, and the thermal deterioration of the exhaust throttle device (8) is suppressed.

The exhaust throttle device (8) includes an exhaust throttle valve (8a), a valve case (8b), a water jacket (8c) along the valve case (8b), and a valve drive actuator (8d) penetrating the water jacket (8c). The bypass cooling water (22a) to the exhaust throttle device (8) passes through the water jacket (8c) and water-cools the valve case (8b) and the valve drive actuator (8d).

As shown in FIG. 3, the exhaust gas recirculation device includes an EGR cooler (23) and a pair of bypass channels (22) (24) individually branched from the main channel (21) for cooling the engine body (20). (8) and the EGR cooler (23) are individually connected to the pair of bypass channels (22) and (24), respectively.
This engine has the following advantages:
The resistance of each of the pair of bypass channels (22) and (24) to which the exhaust throttle device (8) and the EGR cooler (23) are individually connected is small, and the bypass cooling water (22a) to the exhaust throttle device (8) is small. The supply amount of the exhaust gas recirculation device (8) is large, the temperature of the exhaust gas recirculation device (8) is lowered, and the thermal deterioration of the exhaust gas recirculation device (8) is suppressed.
The resistance of each of the pair of bypass channels (22) and (24) is small, the supply amount of the bypass cooling water (24a) to the EGR cooler (23) is large, the temperature of the EGR gas (23a) is lowered, and the EGR gas (23a) is supplied. The density of 23a) increases, and the EGR rate increases.

The EGR cooler (23) includes a plurality of heat dissipation pipes (23b) through which the EGR gas (23a) passes, and a water jacket (23c) surrounding the juxtaposed heat dissipation pipes (23b), and the water jacket (23c) is provided. The EGR gas (23a) is water-cooled by the bypass cooling water (24a) passing through.

As shown in FIG. 3, the main water channel (21) is driven by the cooling water pump (25), and the main cooling water (21a) is the water jacket (20d) of the cylinder block (20a) and the cylinder head (20b). The water jacket (20e) and the radiator (26) are configured to circulate in this order.
The bypass channel (24) to which the EGR cooler (23) is connected is branched from the water jacket (20d) of the cylinder block (20a).
This engine has the following advantages:
The bypass cooling water (24a) separated from the relatively low temperature main cooling water (21a) before the temperature becomes high in the cylinder head (20b) is supplied to the EGR cooler (23), and the cooling performance of the EGR cooler (23) is improved. ..

The bypass channel (22) to which the exhaust throttle device (8) is connected is branched from the water jacket (20e) of the cylinder head (20b).
This engine has the following advantages:
Bypass cooling water (22a) at an appropriate temperature that has absorbed the heat of the cylinder block (20a) and the cylinder head (20b) is supplied to the high-temperature exhaust throttle device (8), causing malfunction due to overcooling of the exhaust throttle device (8). It is suppressed.

As shown in FIG. 3, the water jacket (20e) of the cylinder head (20b) is attached to the radiator (26) with the erection direction of the crank shaft (14) in the front-rear direction, any one of them on the front side, and the other on the rear side. The bypass water channel (22) provided with the main cooling water outlet (20c) for sending out the main cooling water (21a) on the front side and to which the exhaust throttle device (8) is connected is behind the water jacket (20e) of the cylinder head (20b). It is branched from the side.
Therefore, the bypass cooling water (22a) separated from the relatively low temperature main cooling water (21a) before reaching the main cooling water outlet (20c) is supplied to the exhaust throttle device (8), and the exhaust throttle device (8) is supplied. ) Cooling performance is improved.

As shown in FIG. 3, the EGR valve device (27) is provided, and the EGR valve device (27) is a bypass channel (21) branched from the main channel (21) other than the pair of bypass channels (22) and (24). It is connected to 28).
This engine has the following advantages:
The water channel resistance of the bypass water channel (28) to which the EGR cooler (23) and the exhaust gas recirculation device (8) are not connected is small, the supply amount of the bypass cooling water (28a) to the EGR valve device (27) is large, and the EGR The temperature of the valve device (27) is lowered, and the thermal deterioration of the EGR valve device (27) is suppressed.

The EGR valve device (27) includes an EGR valve (27a), a valve case (27b), a water jacket (27c) along the valve case (27b), and a valve drive actuator (27d) penetrated through the water jacket (27c). ), The bypass cooling water (28a) to the EGR valve device (27) passes through the water jacket (27c) and water-cools the valve case (27b) and the valve drive actuator (27d).

As shown in FIG. 3, the bypass channel (28) connected to the EGR valve device (27) is branched from the water jacket (20d) of the cylinder block (20a).
Therefore, the bypass cooling water (28a) separated from the relatively low temperature main cooling water (21a) before the temperature becomes high in the cylinder head (20b) is supplied to the EGR valve device (27), and the EGR valve device (27) Improves cooling performance.

The flow of engine control is as follows.
In this engine, the following control is performed by the control device (10).
The clogging clearing mode shown in FIG. 4 is performed when it is determined that the exhaust inlet (4a) of the catalyst (4) is clogged with unburned deposits.
The DPF regeneration mode shown in FIG. 5 is carried out when PM is deposited on the DPF (12) and a DPF regeneration request is made.
If a DPF regeneration request is made during the execution of the clogging clearing mode, the DPF regeneration mode is carried out after the clogging of the exhaust inlet (4a) of the catalyst (4) is cleared in the clogging clearing mode. ..
If the clogging determination of the catalyst (4) is affirmed during the implementation of the DPF regeneration mode, the DPF regeneration is performed after the clogging of the exhaust inlet (4a) of the catalyst (4) is cleared in the clogging clearing mode. The mode is resumed.

As shown in FIG. 4, in step (S1), it is determined whether or not the exhaust inlet (4a) of the catalyst (4) is clogged with unburned deposits. If the determination of clogging in step (S1) is denied, step (S1) is repeated until the determination is affirmed.
When the cumulative temperature of the exhaust (5) detected by the exhaust temperature sensor (9) of the exhaust outlet (4b) of the catalyst (4) has not reached the predetermined time. Is presumed not to be clogged, the determination in step (S1) is denied, and when the accumulation of the above times reaches a predetermined time, it is presumed to be clogged and in step (S1). Judgment is affirmed. The differential pressure between the exhaust inlet (4a) and the exhaust outlet (4b) of the catalyst (4) is detected, and if the differential pressure is equal to or higher than the predetermined pressure, the determination of clogging is affirmed and the differential pressure is less than the predetermined pressure. In some cases, the determination of clogging may be denied.
If the determination in step (S1) is affirmed, the process proceeds to step (S2-1).

In step (S2-1), it is determined whether or not the temperature of the exhaust (5) detected by the exhaust temperature sensor (9) is in the incineration temperature region of the unburned deposit adhering to the exhaust inlet (4a). If the determination is affirmed, the process proceeds to step (S3). If the determination in step (S2-1) is denied, the opening degree of the exhaust throttle device (8) is adjusted in step (S2-2). The incinerator temperature range is set to, for example, 400 ° C to 450 ° C, and when the detection temperature of the exhaust (5) is lower than this range, the opening degree of the exhaust throttle device (8) is adjusted to be small. When the temperature of the exhaust (5) exceeds this region, the opening degree of the exhaust throttle device (8) is adjusted to be large.

In step (S3), it is determined whether or not the clogging of the catalyst (4) has been cleared. If the determination in step (S3) is affirmed, the process proceeds to step (S4). If the determination in step (S3) is denied, the process returns to step (S2-1).
In step (S3), when the cumulative time for which the temperature of the exhaust gas (5) detected by the exhaust gas temperature sensor (9) is maintained at the incineration temperature of the unburned deposit reaches a predetermined time, the blockage is clogged. Is presumed to have been resolved, the determination in step (S3) is affirmed, and if the accumulation of the above times has not reached the predetermined time, it is presumed that the clogging has not been resolved, and step (S3). ) Is denied. The differential pressure between the exhaust inlet (4a) and the exhaust outlet (4b) of the catalyst (4) is detected, and if the differential pressure is less than the predetermined pressure, the determination in step (S3) is affirmed and the differential pressure is predetermined. If the pressure is greater than or equal to the pressure, the determination in step (S3) may be denied.
In step (S4), the opening degree of the exhaust throttle device (8) is fully opened, and the process returns to step (S1).

As shown in FIG. 5, in step (S5), it is determined whether or not there is a DPF regeneration request, and if the regeneration request determination is affirmed, the process proceeds to step (S6-1) and the DPF regeneration mode is set.
The DPF regeneration request is made by the control device (10) when the estimated accumulation value of PM deposited on the DPF (12) reaches a predetermined value.
The PM deposition estimated value detects the differential pressure between the exhaust inlet (12a) and the exhaust outlet (12b) of the DPF (12), and if the differential pressure is equal to or higher than the predetermined pressure, DPF regeneration is required and the differential pressure. If is less than a predetermined pressure, DPF regeneration is not required.

In the DPF regeneration mode shown in FIG. 5, the catalyst activation in which the target exhaust temperature of the exhaust (5) detected by the exhaust temperature sensor (9) matches the activation of the catalyst (4) and the throttle downstream side catalyst (11). Set in the temperature range.
In step (S6-1) shown in FIG. 5, it is determined whether or not the temperature of the exhaust (5) detected by the exhaust temperature sensor (9) is in the catalyst activation temperature region, and the determination in step (S6-1) is performed. If is affirmed, the process proceeds to step (S7). If the determination in step (S6-1) is denied, the opening degree of the exhaust throttle device (8) is adjusted in step (S6-2), and the process returns to step (S6-1).

The catalyst activation temperature region is set to, for example, 250 ° C to 300 ° C, and when the temperature of the exhaust (5) detected by the exhaust temperature sensor (9) is lower than this region, the exhaust throttle device The opening degree of (8) is adjusted to be small, and when the temperature of the exhaust (5) exceeds this region, the opening degree of the exhaust throttle device (8) is adjusted to be large, and the exhaust (5) The temperature is within the catalyst activation temperature range, which is the target exhaust temperature.
After the temperature of the exhaust (5) reaches the catalyst activation temperature region which is the target exhaust temperature, the target exhaust temperature of the exhaust (5) detected by the exhaust temperature sensor (9) in the control device (10) becomes It is set to the DPF regeneration temperature region that matches the regeneration temperature of DPF (12). The DPF regeneration temperature region is higher than the catalyst activation temperature region, and is set to, for example, 500 ° C to 550 ° C.
Thereby, the temperature of the exhaust inlet (12a) of the DPF (12) is adjusted to 600 ° C to 650 ° C suitable for regeneration of the DPF (12).

In step (S7), post-injection is performed, and the process proceeds to step (S8-1).
The post-injection is a fuel injection performed in the combustion chamber (36) in the expansion stroke or the exhaust stroke after the main injection from the fuel injection valve (35) during the combustion cycle.
The unburned fuel supplied into the exhaust gas (5) by post-injection was catalytically burned by the catalyst (4) and the throttle downstream side catalyst (11), the temperature of the exhaust gas (5) rose, and the fuel was deposited on the DPF (12). The PM is incinerated and removed, and the DPF (12) is regenerated.
The injection timing and injection amount of the post injection injected from the fuel injection valve (35) are the intake amount detected by the air flow sensor case (32) and the back pressure between the catalyst (4) and the exhaust throttle device (8). The back pressure and the temperature of the exhaust (5) detected by the sensor (40) and the exhaust temperature sensor (9), and the exhaust (5) detected by the exhaust temperature sensor (38) of the exhaust inlet (12a) of the DPF (12). ) Is set and controlled by the control device (10) based on the temperature and the like.
In addition to post-injection, the supply of unburned fuel to the exhaust (5) can also be performed by exhaust pipe injection in which fuel is injected by a fuel injection nozzle in the exhaust lead-out path (2).

In step (S8-1), it is determined whether or not the temperature of the exhaust (5) detected by the exhaust temperature sensor (9) is in the catalyst combustion temperature range, and the determination in step (S8-1) is affirmed. Then, the process proceeds to step (S9), and when the determination in step (S8-1) is denied, the opening degree of the exhaust throttle device (8) is adjusted in step (S8-2), and the step (S7) is performed. return. When the temperature of the exhaust (5) detected by the exhaust temperature sensor (9) is less than the catalyst combustion temperature range, the opening of the exhaust throttle device (8) is adjusted to be small, and the exhaust (5) is adjusted. When the temperature exceeds this region, the opening degree of the exhaust throttle device (8) is adjusted to be large, and the detected temperature of the exhaust gas (5) is contained in the catalyst combustion temperature region which is the target exhaust temperature.
In step (S9), it is determined whether or not the temperature of the exhaust (5) detected by the exhaust temperature sensor (38) at the exhaust inlet (12a) of the DPF (12) is in the DPF regeneration temperature region, and in step (S9). If the determination is denied, the process proceeds to step (S10), and if the determination in step (S9) is affirmed, the process returns to step (S7).

In step (S10), it is determined whether or not the DPF regeneration is completed, and if the determination is affirmed, the opening degree of the exhaust gas throttle device (8) is fully opened in step (S11), and the process returns to step (S5). .. If the determination in step (S10) is denied, the process returns to step (S7).
When the cumulative time during which the temperature of the exhaust (5) detected by the exhaust temperature sensor (38) at the exhaust inlet (12a) of the DPF (12) is maintained in the DPF regeneration temperature region reaches a predetermined time, step (S10). If the determination in step (S10) is affirmed and the determination in step (S10) is not reached, the determination in step (S10) is denied. This DPF regeneration temperature region is set to, for example, 600 ° C to 650 ° C. The differential pressure sensor (37) detects the differential pressure between the exhaust inlet (12a) and the exhaust outlet (12b) of the DPF (12), and if the differential pressure is less than the predetermined pressure, the determination in step (S10) is made. If it is affirmed and the differential pressure is equal to or higher than the predetermined pressure, the determination in step (S10) may be denied. When the temperature of the exhaust gas (5) detected by the exhaust temperature sensor (39) on the exhaust outlet (12b) side of the DPF (12) reaches an abnormal temperature exceeding a predetermined upper limit temperature, the DPF regeneration is urgently stopped. The upper limit temperature is set to, for example, 700 ° C.

The main configurations and advantages regarding DPF regeneration are as follows.
As shown in FIG. 1 (B), the catalyst (4), the exhaust temperature sensor (9), the exhaust throttle device (8), the exhaust temperature sensor (9), and the exhaust gas arranged on the exhaust upstream side of the DPF (12). It is provided with a control device (10) in which the throttle device (8) is linked.
As shown in FIGS. 1 (B) and 5, the catalyst activation treatment and the subsequent DPF regeneration treatment are performed under the control of the control device (10), and in the catalyst activation treatment, the exhaust outlet (4) of the catalyst (4) ( The target temperature of the exhaust (5) in 4b) is set in the first temperature region (E1), the opening degree of the exhaust throttle device (8) is controlled, and in the DPF regeneration process, the target temperature is the second. The target temperature of the exhaust (5) of the exhaust inlet (12a) of the DPF (12) is set in the third temperature region (E3) while being set in the temperature region (E2), and the exhaust throttle device (8) is set. The opening degree is controlled and unburned fuel is supplied to the exhaust gas (5).
As shown in FIG. 5, the second temperature region (E2) is higher than the first temperature region (E1), and the third temperature region (E3) is higher than the second temperature region (E2). The temperature difference (T12) between the first temperature region (E1) and the second temperature region (E2) becomes larger than the temperature difference (T23) between the second temperature region (E2) and the third temperature region (E3). Is set to.

This engine has the following advantages:
Even if the exhaust (5) rises due to the catalytic combustion of unburned fuel during the transition from the catalyst activation treatment to the DPF regeneration treatment, the exhaust throttle device is used for the DPF regeneration treatment in which the high second temperature region (E2) is the target temperature. The opening of (8) becomes gradual, and the temperature of the exhaust (5) drops sharply due to an unexpected situation due to the sudden opening of the exhaust particulate filter (8), that is, a sudden drop in back pressure, resulting in post-injection or the like. The supply of unburned fuel is stopped, and the unforeseen situation that the DPF regeneration is stagnant is unlikely to occur, and the DPF regeneration is promoted.

As shown in FIG. 5, the temperature difference (T12) between the first temperature region (E1) for catalyst activation and the second temperature region (E2) for catalyst combustion is in the range of a minimum of 200 ° C to a maximum of 300 ° C. Therefore, the temperature difference (T23) between the temperature region (E2) for catalytic combustion and the third temperature region (T3) for DPF regeneration is in the range of a minimum of 50 ° C to a maximum of 150 ° C.
As shown in FIG. 5, the ratio of the temperature difference (T12) (T23) is a maximum of 300:50 and a minimum of 200:150, that is, a maximum of 6: 1 and a minimum of 1.3: 1.
When the ratio of the temperature difference (T12) (T23) exceeds 6: 1 and the temperature difference (T12) becomes large, the second temperature region (E2) of the catalytic combustion becomes too high, and the exhaust particulate filter (8) becomes hot. It is prone to deterioration, and when the temperature difference (T12) becomes smaller than 1.3: 1, the second temperature region (E2) of catalytic combustion becomes too low, and the exhaust throttle device (8) in the DPF regeneration process The opening becomes abrupt, and the temperature of the exhaust (5) drops abruptly due to an unforeseen situation due to the abrupt opening of the exhaust throttle device (8), that is, a sudden drop in the back pressure, and the unburned fuel due to post injection or the like is used. The supply is stopped, and the unforeseen situation that the DPF regeneration is stagnant is likely to occur, and the DPF regeneration is stagnant.
The post injection is stopped when the temperature of the exhaust gas (5) falls below the catalyst activation temperature region.

As shown in FIGS. 1B and 4, when the exhaust inlet (4a) of the catalyst (4) is clogged with unburned deposits, the clogging clearing process is performed under the control of the control device (10). In the clogging clearing process, the target temperature of the exhaust gas (5) at the exhaust inlet (4a) of the catalyst (4) is set in the incineration temperature region (E0) of the unburned deposits, and the exhaust throttle device (8) It is configured so that the opening degree of is controlled.
Therefore, the clogging clearing process incinerates the unburned deposits that clog the exhaust inlet (4a) of the catalyst (4), and the clogging of the exhaust inlet (4a) of the catalyst (4) is suppressed.

Next, the second embodiment will be described.
The engine of the second embodiment differs from the first embodiment in the following points.
As shown in FIG. 6, the exhaust throttle device (8) and the EGR valve device (27) are connected in series to the bypass water channel (22).
This engine has the following advantages:
By sharing the bypass passage (22), the number of bypass channels is reduced.
Further, since the EGR cooler (23) is not connected to the bypass water channel (22) to which the exhaust gas recirculation device (8) and the EGR valve device (27) are connected, the exhaust gas recirculation device (8) and the EGR valve device (27) are not connected. There is no possibility that the supply amount of the bypass cooling water (24a) to the EGR cooler (23) will be reduced due to the water channel resistance of), the cooling efficiency of the EGR cooler (23) will be maintained high, and the EGR rate will not decrease.

As shown in FIG. 6, the EGR valve device (27) is connected to the upstream side of the bypass water channel (22), and the exhaust throttle device (8) is connected to the downstream side.
In this engine, bypass cooling water (22a) having an appropriate temperature that has absorbed the heat of the EGR valve device (27) is supplied to the high-temperature exhaust gas recirculation device (8), and malfunction due to overcooling of the exhaust gas recirculation device (8) is suppressed. Will be done.

As shown in FIG. 1, the EGR valve device (27) is arranged on the downstream side of the flow path of the EGR gas (23a) with respect to the EGR cooler (23).
In this engine, since the EGR valve device (27) is supplied with the relatively low temperature EGR gas (23a) cooled by the EGR cooler (23), the heat load of the EGR valve device (27) is small, and FIG. As shown in the above, even if the supply amount of the bypass cooling water (22a) is reduced due to the water channel resistance of the exhaust gas recirculation device (8), there is no problem in cooling the EGR valve device (27), and the EGR valve device (27a) The thermal deterioration of 27) is suppressed.

As shown in FIG. 6, the main water channel (21) is driven by the cooling water pump (25), and the main cooling water (21a) is the water jacket (20d) of the cylinder block (20a) and the cylinder head (20b). The water jacket (20e) and the radiator (26) are configured to circulate in this order.
The bypass passage (22) is derived from the water jacket (20d) of the cylinder block (20a).
This engine has the following advantages:
Bypass cooling water (22a) separated from the relatively low temperature main cooling water (21a) before the temperature rises in the cylinder head (20b) is supplied to the EGR valve device (27) and the exhaust gas recirculation device (8), and the EGR valve. The cooling performance of the device (27) and the exhaust gas recirculation device (8) is enhanced.

As shown in FIG. 6, the bypass passage (22) to which the exhaust throttle device (8) is connected is derived from the water jacket (20d) of the cylinder block (20a).
This engine has the following advantages:
Bypass cooling water (22a) separated from the relatively low temperature main cooling water (21a) before the temperature rises in the cylinder head (20b) is supplied to the exhaust throttle device (8), and the cooling performance of the exhaust throttle device (8). Will increase.

As shown in FIG. 6, the bypass passage (22) to which the EGR valve device (27) is connected is derived from the water jacket (20d) of the cylinder block (20a).
This engine has the following advantages:
The bypass cooling water (22a) separated from the relatively low temperature main cooling water (21a) before the temperature of the cylinder head (20b) becomes high is supplied to the EGR valve device (27), and the cooling performance of the EGR valve device (27) is supplied. Will increase.
Other configurations and functions are the same as those of the engine of the first embodiment, and in FIG. 5, the same elements as those of the first embodiment are designated by the same reference numerals as those of FIG. 2 and the like.

(4) ... catalyst, (4c) ... central axis, (4d) ... central through hole, (5a) to (5d) ... exhaust port, (8) ... exhaust throttle device, (9) ... exhaust temperature sensor, (10) ) ... Control device, (11) ... Downstream catalyst, (11a) ... Exhaust inlet, (20) ... Engine body, (21) ... Main channel, (22) ... Bypass channel, (23) ... EGR cooler.

Claims (5)

The catalyst (4) is provided with the exhaust ports (5a) to (5d) and the catalysts (4) arranged in the exhaust ports (5a) to (5d), and the catalyst (4) has a thickness dimension in the central axis (4c) direction. Formed to be thinner than the radial dimensions,
The exhaust throttle device (8) provided downstream of the exhaust of the catalyst (4) is provided.
An EGR cooler (23) and a pair of bypass channels (22) (24) individually branched from a main channel (21) for water cooling the engine body (20) are provided, and an exhaust gas recirculation device (8) and an EGR cooler (8) are provided. 23) are individually connected to the pair of bypass channels (22) and (24), respectively.
It is provided with an exhaust temperature sensor (9) arranged between the catalyst (4) and the exhaust throttle device (8), and a control device (10) for linking the exhaust temperature sensor (9) and the exhaust throttle device (8) for control. The device (10) is characterized in that the opening degree of the exhaust throttle device (8) is adjusted based on the temperature of the exhaust gas (5) detected by the exhaust temperature sensor (9). engine. In the engine according to claim 1,
The catalyst (4) is an engine characterized in that it is formed in a circular shape when viewed in a direction parallel to its central axis (4c). In the engine according to claim 1 or 2.
The catalyst (4) has a central through hole (4d) and is formed in an annular shape when viewed in a direction parallel to the central axis (4c). In the engine according to any one of claims 1 to 3 .
A catalyst (11) on the downstream side of the throttle is provided downstream of the exhaust throttle device (8), and the control device (10) is based on the temperature of the exhaust (5) detected by the exhaust temperature sensor (9). The temperature of the exhaust (5) on the exhaust inlet (11a) side of the exhaust downstream side catalyst (11) of the exhaust throttle device (8) is estimated, and the throttle downstream side catalyst (11) is estimated based on the estimation of the temperature of the exhaust (5). An engine characterized in that it is configured to control exhaust gas treatment using 11). In the engine according to claim 4 ,
The exhaust gas treatment using the throttle downstream side catalyst (11) is accompanied by an exhaust gas temperature rise treatment in which the unburned fuel supplied in the exhaust gas (5) is catalytically burned by the throttle downstream side catalyst (11). ..

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