JP2023067499A - Intake and exhaust system for engine - Google Patents

Abstract

An object of the present invention is to suppress the emission of unburned ammonia.
An intake/exhaust system 1 of an engine 100 includes an engine 100 having a plurality of cylinders, an intake passage 200 communicating with a combustion chamber 108 of each cylinder of the engine 100, an ammonia injection valve provided for each cylinder, Exhaust port 104b of some of the plurality of cylinders (sixth cylinder #6) and other cylinders (first cylinder #1, second cylinder #2, third cylinder #3) , the fourth cylinder #4 and the fifth cylinder #5), and the ammonia equivalence ratio, which is the ratio of the amount of ammonia to the amount of air in some cylinders, is changed to that in other cylinders. and a control device 600 that makes it smaller than the ammonia equivalence ratio.
[Selection drawing] Fig. 1

Description

The present disclosure relates to intake and exhaust systems for engines.

Conventionally, various proposals regarding engines have been made. For example, as disclosed in Japanese Unexamined Patent Application Publication No. 2002-200014, a technique using ammonia as an engine fuel has been proposed. Carbon dioxide emissions are reduced by using ammonia as an engine fuel.

JP 2020-148198 A

By the way, when ammonia is used as the engine fuel, if the ammonia equivalence ratio, which is the ratio of the amount of ammonia supplied to the amount of air supplied to the combustion chamber of the engine, is low, nitrous oxide (N ₂ O), which is a greenhouse gas, is discharged in large quantities. Therefore, it is necessary to increase the ammonia equivalent ratio to some extent. However, increasing the ammonia equivalence ratio increases the amount of unburned ammonia discharged. Therefore, it is desirable to suppress the discharge of unburned ammonia.

An object of the present disclosure is to provide an engine intake and exhaust system capable of suppressing the emission of unburned ammonia.

In order to solve the above problems, the engine intake and exhaust system of the present disclosure includes an engine having a plurality of cylinders, an intake passage communicating with the combustion chamber of each cylinder of the engine, and an ammonia injection valve provided for each cylinder. , the ratio of the amount of ammonia to the amount of air in the supply flow path that communicates the exhaust port of some of the multiple cylinders and the intake port of other cylinders other than some cylinders, and the amount of ammonia in some cylinders and a control device that makes a certain ammonia equivalence ratio smaller than the ammonia equivalence ratio in other cylinders.

An exhaust channel that communicates with the combustion chamber of another cylinder, a connection channel that communicates the exhaust channel and the supply channel, and an exhaust port and the exhaust channel of some cylinders communicate through the connection channel. and a first state in which the exhaust ports of some cylinders and the intake ports of other cylinders are not in communication with each other through the supply passages, and the exhaust ports of some cylinders and the exhaust passages form connection passages. a switching valve that switches between a second state in which the exhaust ports of some cylinders and the intake ports of other cylinders communicate with each other through a supply flow path.

The control device causes the switching valve to switch to the second state when the load of the engine is lower than the reference load, and makes the ammonia equivalence ratio in some cylinders smaller than the ammonia equivalence ratio in other cylinders. good too.

The control device causes the switching valve to switch to the second state when the intake air temperature is lower than the reference temperature, even if the ammonia equivalence ratio in some cylinders is smaller than the ammonia equivalence ratio in other cylinders. good.

According to the present disclosure, emission of unburned ammonia can be suppressed.

FIG. 1 is a schematic diagram showing the configuration of an intake and exhaust system according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram showing the configuration of each cylinder of the engine according to the embodiment of the present disclosure. FIG. 3 is a flowchart showing an example of the flow of processing performed by the control device according to the embodiment of the present disclosure. FIG. 4 is a schematic diagram showing the configuration of an intake/exhaust system according to a modification. FIG. 5 is a schematic diagram showing gas flow when the communication state is the first state in the intake and exhaust system according to the modification. FIG. 6 is a schematic diagram showing gas flow when the communication state is the second state in the intake and exhaust system according to the modification. FIG. 7 is a flowchart showing the flow of the first processing example performed by the control device according to the modification. FIG. 8 is a flow chart showing the flow of the second processing example performed by the control device according to the modification.

Embodiments of the present disclosure will be described below with reference to the accompanying drawings. Dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding, and do not limit the present disclosure unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are given the same reference numerals to omit redundant description, and elements that are not directly related to the present disclosure are omitted from the drawings. do.

FIG. 1 is a schematic diagram showing the configuration of an intake and exhaust system 1 according to this embodiment. The intake/exhaust system 1 is a system related to intake and exhaust of the engine 100 . As shown in FIG. 1 , the intake/exhaust system 1 includes an engine 100 , an intake passage 200 , an exhaust passage 300 , a supercharger 400 , a supply passage 500 and a control device 600 .

Engine 100 is a diesel engine. Engine 100 has a plurality of cylinders. In the example of FIG. 1, the engine 100 includes a first cylinder #1, a second cylinder #2, a third cylinder #3, a fourth cylinder #4, a fifth cylinder #5, and a sixth cylinder #6. and However, the number of cylinders of engine 100 may be other than six.

FIG. 2 is a schematic diagram showing the configuration of each cylinder of engine 100 according to the present embodiment. In FIG. 2, intake port 104a, exhaust port 104b, ammonia injector 112 and non-ammonia fuel injector 114 are shown on the same cross section. However, the intake port 104a, the exhaust port 104b, the ammonia injection valve 112 and the non-ammonia fuel injection valve 114 do not have to be positioned on the same cross section.

As shown in FIG. 2, engine 100 includes cylinder liner 102 , cylinder head 104 and piston 106 . A piston 106 is housed within the cylinder liner 102 . Combustion chamber 108 is formed by cylinder liner 102 , cylinder head 104 and piston 106 .

The cylinder head 104 is formed with an intake port 104a and an exhaust port 104b. Intake port 104 a and exhaust port 104 b open into combustion chamber 108 . The intake valve 110a opens and closes the opening of the intake port 104a on the combustion chamber 108 side. The exhaust valve 110b opens and closes the opening of the exhaust port 104b on the combustion chamber 108 side. The opening and closing operations of the intake valve 110a and the exhaust valve 110b are performed with rotation of a camshaft (not shown).

A pipe that forms a branch flow path 202 of an intake flow path 200, which will be described later, is connected to the intake port 104a. Intake air flows into the combustion chamber 108 via the intake port 104a. A pipe forming a branch channel 302 of an exhaust channel 300, which will be described later, is connected to the exhaust port 104b. Exhaust gas is discharged from the combustion chamber 108 through the exhaust port 104b. As will be described later, the exhaust port 104b of the sixth cylinder #6 among the plurality of cylinders is connected to the pipe forming the supply flow path 500 instead of the pipe forming the exhaust flow path 300. FIG.

Ammonia injector 112 is connected to a source of ammonia used as fuel. The ammonia supply source is, for example, an ammonia tank (not shown). In the example of FIG. 2 , the ammonia injection valve 112 is provided in the branch flow path 202 of the intake flow path 200 . A tip portion of the ammonia injection valve 112 faces the intake port 104a. The ammonia injection valve 112 injects ammonia as fuel gas into the intake port 104a. Gaseous ammonia is injected from the ammonia injection valve 112 . Thus, engine 100 is an engine that uses ammonia as fuel.

However, ammonia injection valve 112 may be provided in combustion chamber 108 . In this case, the ammonia injection valve 112 is provided, for example, in the cylinder head 104 so as to face the combustion chamber 108 and directly injects ammonia into the combustion chamber 108 . In this case, gaseous or liquid ammonia is injected from the ammonia injection valve 112 . Thus, the ammonia injection valve 112 is provided for each cylinder in the intake passage 200 or the combustion chamber 108 .

The non-ammonia fuel injection valve 114 is connected to a non-ammonia fuel supply source other than ammonia. Light oil, for example, is used as the non-ammonia fuel. In this case, the non-ammonia fuel supply source is, for example, a light oil tank (not shown). However, a fuel other than light oil, such as heavy oil, may be used as the non-ammonia fuel. A non-ammonia fuel injector 114 is provided in the combustion chamber 108 . In the example of FIG. 2 , the non-ammonia fuel injection valve 114 is provided in the cylinder head 104 so as to face the combustion chamber 108 and directly injects the non-ammonia fuel into the combustion chamber 108 . For example, liquid non-ammonia fuel is injected from the non-ammonia fuel injection valve 114 .

Ammonia has flame retardancy, which makes it difficult to burn compared to other fuels. Therefore, in engine 100, non-ammonia fuel is used in addition to ammonia as fuel in order to ensure combustibility in combustion chamber .

Engine 100 is a four-cycle engine. In the intake stroke, ammonia is injected from the ammonia injection valve 112, the intake valve 110a is opened, and the exhaust valve 110b is closed. The piston 106 moves to the bottom dead center, and intake air and ammonia are taken into the combustion chamber 108 from the intake port 104a. In the compression stroke, the intake valve 110a and the exhaust valve 110b are closed. Piston 106 moves to top dead center and the mixture in combustion chamber 108 is compressed. At the timing when the piston 106 reaches near the top dead center, the non-ammonia fuel is injected from the non-ammonia fuel injection valve 114 to enhance the combustibility in the combustion chamber 108 . Thereby, the air-fuel mixture in the combustion chamber 108 is ignited and combusted. In the expansion stroke, the piston 106 is pushed toward the bottom dead center. In the exhaust stroke, the intake valve 110a is closed and the exhaust valve 110b is opened. The piston 106 moves to the top dead center, and exhaust gas after combustion is discharged from the combustion chamber 108 through the exhaust port 104b. Hereinafter, returning to FIG. 1, description will be continued.

Intake flow path 200 communicates with combustion chamber 108 of each cylinder of engine 100 . Intake air, which is the air supplied to the combustion chamber 108 , flows through the intake passage 200 . An intake port (not shown) through which air is taken in from the outside is provided at the upstream end of the intake passage 200 . The intake flow path 200 has a plurality of branch flow paths 202 that respectively communicate with the combustion chambers 108 of the cylinders. A plurality of branch channels 202 are provided downstream of the intake channel 200 . The combustion chamber 108 and intake passage 200 of each cylinder are connected by a plurality of branch passages 202 . As described above, the pipe forming branch flow path 202 is connected to intake port 104 a of engine 100 . The intake port 104 a corresponds to the downstream end of the branch flow path 202 . Intake port 104 a is included in intake channel 200 .

A branched flow path 202 connected to the sixth cylinder #6 branches off from the first position P1 in the intake flow path 200 . The branch flow path 202 connected to the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4, and the fifth cylinder #5 is located from the first position P1 in the intake flow path 200. It branches from the second position P2 on the downstream side.

The exhaust passage 300 communicates with the combustion chambers 108 of the first cylinder #1, second cylinder #2, third cylinder #3, fourth cylinder #4 and fifth cylinder #5. Exhaust gas discharged from the combustion chamber 108 flows through the exhaust passage 300 . An exhaust port (not shown) through which the exhaust gas is discharged to the outside is provided at the downstream end of the exhaust passage 300 . The exhaust passage 300 has a plurality of branched flows that communicate with the combustion chambers 108 of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4, and the fifth cylinder #5. It has a path 302 . A plurality of branch channels 302 are provided upstream of the exhaust channel 300 . As described above, the pipe forming the branch flow path 302 is connected to the exhaust port 104 b of the engine 100 . The exhaust ports 104b of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4, and the fifth cylinder #5 correspond to the upstream end of the branch flow path 302. . The exhaust ports 104 b of the first cylinder # 1 , the second cylinder # 2 , the third cylinder # 3 , the fourth cylinder # 4 and the fifth cylinder # 5 are included in the exhaust passage 300 .

The supercharger 400 has a compressor 402 and a turbine 404 . The impeller of compressor 402 and the impeller of turbine 404 rotate as a unit. The impeller of compressor 402 and the impeller of turbine 404 are connected by a shaft.

The compressor 402 is provided upstream of the first position P1 in the intake passage 200 . Compressor 402 compresses the intake air taken in from the intake port and delivers it to the downstream side. Intake air sent from the compressor 402 is sent to each combustion chamber 108 via each branch flow path 202 .

The turbine 404 is provided downstream of the branch flow path 302 in the exhaust flow path 300 . Exhaust gases discharged from engine 100 are channeled to turbine 404 via each branch flow path 302 . Turbine 404 generates rotational power by rotating the impeller of turbine 404 with the exhaust gas. Rotational power generated by turbine 404 is transmitted to compressor 402 via a shaft. Exhaust gas that has passed through the turbine 404 is discharged from an exhaust port.

The supply flow path 500 includes the exhaust port 104b of the sixth cylinder #6 and the intake ports 104a of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5. communicate with. Exhaust gas discharged from the exhaust port 104 b of the sixth cylinder # 6 is sent to the supply passage 500 . In the supply flow path 500, the exhaust port 104b side of the sixth cylinder #6 is called the upstream side, and the opposite side to the exhaust port 104b side of the sixth cylinder #6 is called the downstream side.

The upstream end of the supply passage 500 is connected to the exhaust port 104b of the sixth cylinder #6. In the example of FIG. 1, the downstream end of the supply channel 500 is connected to the intake channel 200 downstream from the first position P1 and upstream from the second position P2. Therefore, the exhaust gas discharged from the exhaust port 104b of the sixth cylinder #6 passes through the supply passage 500 and flows downstream from the first position P1 and upstream from the second position P2 in the intake passage 200. sent to the side. Then, the exhaust gas sent from the supply channel 500 to the intake channel 200 is taken into the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5. Port 104a feeds the combustion chambers 108 of these cylinders.

The control device 600 includes a central processing unit (CPU), a ROM storing programs and the like, a RAM as a work area, and the like. The control device 600 controls the operation of each device in the intake and exhaust system 1 . For example, control device 600 controls the operation of each device of engine 100 .

The control device 600 also acquires information from sensors in the intake and exhaust system 1 . For example, in the intake/exhaust system 1 , an intake pressure sensor 204 is provided in the intake passage 200 . The intake pressure sensor 204 detects intake pressure, which is the pressure of intake air in the intake passage 200 . In the example of FIG. 1, the intake pressure sensor 204 is provided in the intake passage 200 upstream of the first position P1.

In particular, control device 600 can control the ammonia equivalence ratio of each cylinder by controlling the ammonia injection amount, which is the injection amount of ammonia injected from ammonia injection valve 112 . The ammonia equivalence ratio is the ratio of the amount of ammonia supplied to the amount of air supplied to the combustion chamber 108 . By appropriately controlling the ammonia equivalence ratio of each cylinder, the emission of unburned ammonia is suppressed, as will be described later. The control of the ammonia equivalence ratio by the controller 600 will be described below with reference to FIG.

FIG. 3 is a flowchart showing an example of the flow of processing performed by the control device 600 according to this embodiment. For example, the control flow shown in FIG. 3 is repeatedly executed at preset time intervals.

When the control flow shown in FIG. 3 is started, in step S101, the control device 600 estimates the amount of air supplied to the combustion chamber 108 of each cylinder. Control device 600 can estimate the amount of air supplied to combustion chamber 108 of each cylinder based on the detection result of intake pressure sensor 204, for example.

After step S101, in step S102, the control device 600 controls the ammonia injection amount of each cylinder so that the ammonia equivalence ratio of the sixth cylinder #6 becomes smaller than the ammonia equivalence ratio of the other cylinders. The control flow indicated at 3 ends. The other cylinders mentioned above are the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5.

For example, the control device 600 determines the ammonia equivalence ratio in each of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4, and the fifth cylinder #5 as N ₂ O emissions. is controlled to a value high enough to suppress On the other hand, the control device 600 controls the ammonia equivalence ratio in the sixth cylinder #6 to a value low enough to discharge a large amount of _N2O . Therefore, the exhaust gas discharged from the exhaust port 104b of the sixth cylinder #6 contains a large amount of _N2O . Then, the exhaust gas containing N ₂ O is sent to the supply passage 500, passes through the supply passage 500, and enters the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder # It is supplied to the combustion chambers 108 of the 4th and 5th cylinders #5.

Here, the N ₂ O supplied to the combustion chambers 108 of the first cylinder #1, second cylinder #2, third cylinder #3, fourth cylinder #4, and fifth cylinder #5 is promote combustion within 108; Specifically, N ₂ O is decomposed into N ₂ and O ₂ in the combustion chamber 108, which is a high temperature environment. Combustion in the combustion chamber 108 is accelerated by O ₂ produced by such a decomposition reaction. This suppresses the discharge of unburned ammonia from each of the first cylinder #1, second cylinder #2, third cylinder #3, fourth cylinder #4 and fifth cylinder #5.

As described above, in the intake/exhaust system 1, the control device 600 adjusts the ammonia equivalence ratio of the sixth cylinder #6, which is one of the cylinders, to the other cylinders, the first cylinder #1 and the second cylinder #2. , the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5. This suppresses the discharge of unburned ammonia from each of the first cylinder #1, second cylinder #2, third cylinder #3, fourth cylinder #4 and fifth cylinder #5. Furthermore, since the ammonia equivalence ratio in each of the first cylinder #1, second cylinder #2, third cylinder #3, fourth cylinder #4, and fifth cylinder #5 can be made sufficiently high, N ₂ Emission of O is also appropriately suppressed.

An example in which the supply flow path 500 is connected to the exhaust port 104b of the sixth cylinder #6 has been described above with reference to FIG. However, the supply flow path 500 may be connected to the exhaust port 104b of a cylinder other than the sixth cylinder #6. Also, the supply flow path 500 may be connected to the exhaust ports 104b of two or more cylinders.

An example in which the downstream end of the supply channel 500 is connected to the downstream side of the first position P1 and the upstream side of the second position P2 in the intake channel 200 has been described above with reference to FIG. . However, the downstream side of the supply channel 500 may be branched and connected to each branch channel 202 .

Hereinafter, an intake/exhaust system 1A according to a modification will be described with reference to FIGS. 4 to 8. FIG.

FIG. 4 is a schematic diagram showing the configuration of an intake/exhaust system 1A according to a modification. As shown in FIG. 4, the intake/exhaust system 1A according to the modification differs from the intake/exhaust system 1 described above mainly in that a connection flow path 700 and a switching valve 800 are further provided.

As shown in FIG. 4 , in the intake/exhaust system 1A, the exhaust flow path 300 and the supply flow path 500 communicate with each other via the connection flow path 700 . In the example of FIG. 4 , the connection channel 700 is connected to the upstream side of the junction of the plurality of branch channels 302 in the exhaust channel 300 . However, the connection flow path 700 may be connected to the upstream side of the confluence portion of the plurality of branch flow paths 302 in the exhaust flow path 300 .

The switching valve 800 is provided at a portion of the supply channel 500 that is connected to the connection channel 700 . The switching valve 800 is, for example, a three-way valve. The switching valve 800 changes the communication state of the intake/exhaust system 1A between a first state in which a portion of the supply flow path 500 upstream of the switching valve 800 communicates with the connection flow path 700, The state is switched to the second state in which the more upstream portion communicates with the downstream portion of the switching valve 800 in the supply flow path 500 .

FIG. 5 is a schematic diagram showing gas flow when the communication state is the first state in the intake and exhaust system 1A according to the modification. In the first state, a portion of the supply channel 500 on the upstream side of the switching valve 800 communicates with the connection channel 700 . On the other hand, the portion of the supply channel 500 upstream of the switching valve 800 does not communicate with the portion of the supply channel 500 downstream of the switching valve 800 . That is, in the first state, the exhaust port 104b of the sixth cylinder #6 and the exhaust passage 300 communicate with each other through the connection passage 700, and the exhaust port 104b of the sixth cylinder #6 and the first cylinder #1 are connected. , the second cylinder #2, the third cylinder #3, the fourth cylinder #4, and the fifth cylinder #5 do not communicate with each other through the supply passage 500. Therefore, as shown in FIG. 5, the exhaust gas discharged from the exhaust port 104b of the sixth cylinder #6 passes through the connecting passage 700 and is sent to the exhaust passage 300. As shown in FIG.

FIG. 6 is a schematic diagram showing gas flow when the communication state is the second state in the intake and exhaust system 1A according to the modification. In the second state, the portion of the supply channel 500 upstream of the switching valve 800 communicates with the portion of the supply channel 500 downstream of the switching valve 800 . On the other hand, the portion of the supply channel 500 upstream of the switching valve 800 does not communicate with the connection channel 700 . That is, in the second state, the exhaust port 104b of the sixth cylinder #6 and the exhaust passage 300 do not communicate with each other through the connection passage 700, and the exhaust port 104b of the sixth cylinder #6 and the first cylinder #6 are not communicated with each other. 1, the intake ports 104a of the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5 communicate with each other through the supply passage 500. Therefore, as shown in FIG. 6, the exhaust gas discharged from the exhaust port 104b of the sixth cylinder #6 passes through the supply passage 500 to the first cylinder #1, the second cylinder #2 and the third cylinder. It is sent to the intake ports 104a of #3, the fourth cylinder #4 and the fifth cylinder #5 and supplied to the combustion chambers 108 of these cylinders.

Further, as shown in FIG. 4, in the intake/exhaust system 1A, an intake air temperature sensor 206 is further provided in the intake passage 200. As shown in FIG. An intake air temperature sensor 206 detects intake air temperature, which is the temperature of intake air in the intake air passage 200 . Since the intake air temperature approximately matches the outside air temperature, for example, a sensor that detects the outside air temperature can be used as the intake air temperature sensor 206 . The intake air temperature sensor 206 may be provided in the intake air passage 200 or may be provided in a location other than the air intake passage 200 . A detection result of intake air temperature sensor 206 is output to control device 600 .

As described above, in the intake/exhaust system 1A, the switching valve 800 communicates the exhaust port 104b of the sixth cylinder #6 with the exhaust passage 300 via the connection passage 700, and and the intake ports 104a of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5 do not communicate with each other through the supply passage 500. In state 1, the exhaust port 104b of the sixth cylinder #6 and the exhaust passage 300 do not communicate with each other via the connection passage 700, and the exhaust port 104b of the sixth cylinder #6 and the first cylinder #1 and the first The second state in which the intake ports 104a of the second cylinder #2, the third cylinder #3, the fourth cylinder #4, and the fifth cylinder #5 communicate with each other through the supply passage 500 is switched.

In the first state, the ammonia equivalence ratio in the sixth cylinder #6 is the same as the ammonia equivalence ratio in the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5. By setting it to a degree, the output of the sixth cylinder #6 is increased to the same level as the other cylinders. In the second state, similarly to the intake/exhaust system 1 described above, the ammonia equivalence ratio in the sixth cylinder #6 is set to the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4, and the By making it smaller than the ammonia equivalence ratio in the fifth cylinder #5, the ammonia in the combustion chambers 108 of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5 Combustion is accelerated. This suppresses the discharge of unburned ammonia.

Therefore, when acceleration of combustion in the combustion chambers 108 of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4, and the fifth cylinder #5 is unnecessary, the intake/exhaust system 1A By setting the communication state to the first state, the output of engine 100 is increased. On the other hand, when it is necessary to promote combustion in the combustion chambers 108 of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4, and the fifth cylinder #5, the intake/exhaust system 1A By setting the communication state to the second state, the discharge of unburned ammonia is appropriately suppressed.

Hereinafter, with reference to FIGS. 7 and 8, a first processing example and a second processing example regarding switching of the communication state in the intake/exhaust system 1A and control of the ammonia equivalence ratio will be described.

FIG. 7 is a flow chart showing the flow of the first processing example performed by the control device 600 . For example, the control flow shown in FIG. 7 is repeatedly executed at preset time intervals.

When the control flow shown in FIG. 7 is started, control device 600 acquires the load of engine 100 in step S201.

After step S201, in step S202, control device 600 determines whether or not the load of engine 100 is lower than the reference load. Here, the lower the load of the engine 100, the lower the combustibility in the combustion chamber 108 and the more likely unburned ammonia is produced. Therefore, the need to promote combustion in the combustion chambers 108 of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5 increases. The reference load is set to the extent that it can be determined that the acceleration of combustion in the combustion chambers 108 of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5 is necessary. Set to low load.

When the load of the engine 100 is lower than the reference load, it is necessary to promote combustion in the combustion chambers 108 of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5. situation. On the other hand, when the load of the engine 100 is greater than or equal to the reference load, combustion in the combustion chambers 108 of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5 No promotion is required.

If it is determined that the load of engine 100 is greater than or equal to the reference load (step S202/NO), the process proceeds to step S203. In step S203, the control device 600 causes the switching valve 800 to switch to the first state, thereby switching the communication state of the intake/exhaust system 1A to the first state.

After step S203, in step S204, the control device 600 makes the ammonia equivalence ratio of the sixth cylinder #6 approximately the same as the ammonia equivalence ratios of the other cylinders, and the control flow shown in FIG. 7 ends.

On the other hand, if it is determined that the load of engine 100 is lower than the reference load (step S202/YES), the process proceeds to step S205. In step S205, the control device 600 causes the switching valve 800 to switch to the second state, thereby switching the communication state of the intake/exhaust system 1A to the second state.

After step S205, in step S206, the control device 600 makes the ammonia equivalence ratio of the sixth cylinder #6 smaller than the ammonia equivalence ratios of the other cylinders, and the control flow shown in FIG. 7 ends.

Specifically, the control of the ammonia equivalence ratio of each cylinder in steps S204 and S206 is performed based on the estimated value of the amount of air supplied to the combustion chamber 108 of each cylinder, as described above.

As described above, in the first processing example of FIG. 7, the control device 600 causes the switching valve 800 to switch to the second state when the load of the engine 100 is lower than the reference load. The ammonia equivalence ratio in the sixth cylinder #6, which is the cylinder, is changed to the ammonia equivalence ratio in the other cylinders, the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4, and the fifth cylinder #5. Make it smaller than the equivalence ratio. Thereby, it is possible to determine whether or not acceleration of combustion in the combustion chambers 108 of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5 is necessary. After appropriately judging based on the load, the communication state of the intake/exhaust system 1A can be switched. Therefore, the output of engine 100 is increased when combustion promotion is not required, while the emission of unburned ammonia is appropriately suppressed when combustion promotion is required.

FIG. 8 is a flow chart showing the flow of the second processing example performed by the control device 600 . For example, the control flow shown in FIG. 8 is repeatedly executed at preset time intervals.

The second processing example in FIG. 8 differs from the first processing example in FIG. 7 described above in that steps S201 and S202 are replaced with steps S301 and S302.

When the control flow shown in FIG. 8 is started, control device 600 acquires the intake air temperature in step S301. Intake air temperature may be obtained from intake air temperature sensor 206, for example.

After step S301, in step S302, control device 600 determines whether the intake air temperature is lower than the reference temperature. Here, the lower the intake air temperature, the lower the combustibility in the combustion chamber 108 and the more likely unburned ammonia is produced. Therefore, the need to promote combustion in the combustion chambers 108 of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5 increases. The reference temperature is such that it can be judged that promotion of combustion in the combustion chambers 108 of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5 is necessary. Set to low temperature.

When the intake air temperature is lower than the reference temperature, the situation where it is necessary to promote combustion in the combustion chambers 108 of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5 become. On the other hand, when the intake air temperature is equal to or higher than the reference temperature, combustion is promoted in the combustion chambers 108 of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5. unnecessary situation.

If it is determined that the intake air temperature is equal to or higher than the reference temperature (step S302/NO), the process proceeds to step S203. Then, steps S203 and S204 are performed in the same manner as in the first processing example shown in FIG. 7, and the control flow shown in FIG. 8 ends.

On the other hand, if it is determined that the intake air temperature is lower than the reference temperature (step S302/YES), the process proceeds to step S205. Then, steps S205 and S206 are performed in the same manner as in the first processing example shown in FIG. 7, and the control flow shown in FIG. 8 ends.

As described above, in the second processing example of FIG. 8, when the intake air temperature is lower than the reference temperature, the control device 600 causes the switching valve 800 to switch to the second state, causing some cylinders to switch to the second state. The ammonia equivalence ratio of a sixth cylinder #6 is changed to the ammonia equivalence ratio of the other cylinders of the first cylinder #1, second cylinder #2, third cylinder #3, fourth cylinder #4 and fifth cylinder #5. be smaller than Accordingly, whether acceleration of combustion in the combustion chambers 108 of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4 and the fifth cylinder #5 is necessary or not is determined by the intake air temperature. Based on this, it is possible to switch the communication state of the intake/exhaust system 1A. Therefore, the output of engine 100 is increased when combustion promotion is not required, while the emission of unburned ammonia is appropriately suppressed when combustion promotion is required.

Control device 600 may use both the load of engine 100 being lower than the reference load and the intake air temperature being lower than the reference temperature as conditions for switching the communication state of intake/exhaust system 1A to the second state. good. For example, control device 600 may cause switching valve 800 to switch to the second state when the load of engine 100 is lower than the reference load and the intake air temperature is lower than the reference temperature. For example, the control device 600 switches the switching valve 800 to the second state when either the load of the engine 100 is lower than the reference load or the intake air temperature is lower than the reference temperature is satisfied. You can let the

An example in which the switching valve 800 is a three-way valve has been described above. However, the switching valve 800 is not limited to the above example as long as the communication state of the intake/exhaust system 1A can be switched between the first state and the second state. For example, a first on-off valve provided in the connection channel 700 and a second on-off valve provided in the supply channel 500 on the downstream side of the connecting portion with the connection channel 700 may be used as the switching valve 800. good. In this case, by opening the first on-off valve and closing the second on-off valve, the communication state of the intake/exhaust system 1A becomes the first state. On the other hand, by opening the second on-off valve and closing the first on-off valve, the communication state of the intake/exhaust system 1A becomes the second state.

Although the embodiments of the present disclosure have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to such embodiments. It is clear that a person skilled in the art can conceive of various modifications or modifications within the scope of the claims, and it is understood that these also belong to the technical scope of the present disclosure. be done.

The present disclosure, for example, achieves Goal 7 of Sustainable Development Goals (SDGs) led by the United Nations. It can contribute to "Ensuring access to affordable, reliable, sustainable and modern energy."

1 intake and exhaust system 1A intake and exhaust system 100 engine 104a intake port 104b exhaust port 108 combustion chamber 112 ammonia injection valve 200 intake flow path 300 exhaust flow path 500 supply flow path 600 control device 700 connection flow path 800 switching valve

Claims (4)

an engine having multiple cylinders;
an intake passage communicating with a combustion chamber of each cylinder of the engine;
an ammonia injection valve provided for each cylinder;
a supply flow path communicating between exhaust ports of some of the plurality of cylinders and intake ports of cylinders other than the some of the cylinders;
a control device that makes the ammonia equivalence ratio, which is the ratio of the amount of ammonia to the amount of air in some of the cylinders, smaller than the ammonia equivalence ratio in the other cylinders;
comprising
engine intake and exhaust system. an exhaust passage that communicates with the combustion chamber of the other cylinder;
a connection channel that connects the exhaust channel and the supply channel;
The exhaust ports of the some cylinders and the exhaust flow path communicate with each other through the connection flow path, and the exhaust ports of the some cylinders and the intake ports of the other cylinders communicate with the supply flow path. a first state in which communication between the exhaust ports of the some cylinders and the exhaust passages is not communicated through the connection passages, and the exhaust ports of the some cylinders and the other cylinders do not communicate with each other through the connection passages; a switching valve for switching between a second state in which the intake port of the
comprising
The engine intake and exhaust system according to claim 1. The control device causes the switching valve to switch to the second state when the load of the engine is lower than the reference load, and changes the ammonia equivalence ratio in the one cylinder to the ammonia equivalence ratio in the other cylinder. be less than the ammonia equivalence ratio,
3. The engine intake and exhaust system according to claim 2. The control device causes the switching valve to switch to the second state when the intake air temperature is lower than the reference temperature, and changes the ammonia equivalence ratio in the one cylinder to the ammonia equivalence ratio in the other cylinder. be less than the ratio,
4. The engine intake and exhaust system according to claim 2 or 3.

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