JP2023046453A - engine system - Google Patents

Abstract

To suppress emission of environmental load components even when a catalyst is not activated.SOLUTION: An engine system includes; an engine having a first cylinder, a second cylinder, and a connection port for connecting the first cylinder and the second cylinder in series; and a control device for controlling the engine. The control device has one or a plurality of processors, and one or a plurality of memories connected to the processors. The processor executes processing including: controlling the engine so that a fuel is burnt in a rich atmosphere in the first cylinder and the fuel is burnt in a stoichiometric atmosphere in the second cylinder in a cold state of the engine; and controlling the second cylinder to be in an intake stoke when the first cylinder is in an exhaust stroke, and introducing exhaust air of the first cylinder to the second cylinder via the connection port.SELECTED DRAWING: Figure 2

Description

The present invention relates to engine systems.

For example, Patent Document 1 discloses an engine in which a branch pipe branched from an exhaust pipe of a cylinder in an exhaust stroke is connected to an intake pipe of a cylinder in an intake stroke. In such an engine, the exhaust gas from the cylinder on the exhaust stroke is supplied to the cylinder on the intake stroke.

Japanese Utility Model No. 59-196566

By the way, when the engine is in a cold state from the start of the engine until the catalyst is activated, the catalyst for purifying the exhaust gas is not activated. Therefore, when the engine is cold, environmental load components such as hydrocarbons (HC), carbon monoxide (CO), soot (PM or PN), and nitrogen oxides (NOx) may be discharged into the atmosphere. A cause of emission of environmental load components when the engine is cold is, for example, that the fuel injected into the cylinder adheres to the wall surface of the combustion chamber. When the temperature of the wall surface of the combustion chamber is low, the liquid fuel adhering to the wall surface is difficult to vaporize. However, the technique described in Patent Literature 1 cannot deal with such a problem.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an engine system capable of suppressing the emission of environmental load components even when the catalyst is not activated.

In order to solve the above problems, an engine system according to one embodiment of the present invention includes:
an engine having a first cylinder, a second cylinder, and a connection port that connects the first cylinder and the second cylinder in series;
a control device that controls the engine;
with
The control device is
one or more processors;
one or more memories connected to the processor;
has
The processor
controlling the engine so that when the engine is cold, fuel is burned in a rich atmosphere in the first cylinder and fuel is burned in a stoichiometric atmosphere in the second cylinder;
controlling the second cylinder to an intake stroke when the first cylinder is in an exhaust stroke, and introducing exhaust gas from the first cylinder into the second cylinder through the connection port;
Execute the process including

EFFECTS OF THE INVENTION According to the present invention, it is possible to suppress the emission of environmentally hazardous components even if the catalyst is not activated.

FIG. 1 is a schematic diagram showing the configuration of an engine system according to this embodiment. FIG. 2 is a schematic diagram of the engine system showing the first and second cylinders in longitudinal section. FIG. 3 is a schematic plan view of the first and second cylinders viewed from above. FIG. 4 is a diagram for explaining strokes in each cylinder. FIG. 5 is a diagram for explaining special actions. FIG. 6 is a diagram for explaining normal operation. FIG. 7 is a time chart for explaining the time transition of control of the engine by the control device. FIG. 8 is a flow chart for explaining the operation flow of the control device.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in such embodiments are merely examples for facilitating understanding of the invention, and do not limit the invention 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 invention are omitted from the drawings. do.

FIG. 1 is a schematic diagram showing the configuration of an engine system 1 according to this embodiment. The engine system 1 has an engine 10 and a control device 12 . The engine 10 is mounted on a vehicle, for example.

Engine 10 is, for example, a horizontally opposed engine and has right bank 20 and left bank 22 . The engine 10 has four cylinders, an A cylinder 30a, a B cylinder 30b, a C cylinder 30c and a D cylinder 30d. For example, the A cylinder 30a and the C cylinder 30c are provided in the right bank 20 of the horizontally opposed engine, and the B cylinder 30b and the D cylinder 30d are provided in the left bank 22 of the horizontally opposed engine. Alternatively, the A cylinder 30 a and the C cylinder 30 c may be provided on the left bank 22 , and the B cylinder 30 b and the D cylinder 30 d may be provided on the right bank 20 . Further, the A cylinder 30a, the B cylinder 30b, the C cylinder 30c, and the D cylinder 30d may be collectively referred to simply as cylinders.

Here, the C cylinder 30c of the right bank 20 is the first cylinder, and the A cylinder 30a of the right bank 20 is the second cylinder. The D cylinder 30d of the left bank 22 is the first cylinder, and the B cylinder 30b of the left bank 22 is the second cylinder. The engine 10 has a connection port 32 that connects the first cylinder and the second cylinder in series. The connection port 32 communicates the combustion chamber of the first cylinder and the combustion chamber of the second cylinder. Specifically, a C cylinder 30c as the first cylinder and an A cylinder 30a as the second cylinder are connected by a connection port 32 in the right bank 20, and a D cylinder 30d as the first cylinder and a second cylinder are connected. B cylinder 30 b is connected at a connection port 32 in the left bank 22 .

The engine 10 has an intake valve 40 , an exhaust valve 42 , a first valve 44 , a second valve 46 and a valve mechanism 48 . As will be described later, the intake valve 40 is provided in the intake port, and the exhaust valve 42 is provided in the exhaust port. The first valve 44 is provided on the first cylinder side of the connection port 32 , and the second valve 46 is provided on the second cylinder side of the connection port 32 . The valve mechanism 48 opens and closes the intake valve 40 , the exhaust valve 42 , the first valve 44 and the second valve 46 .

Controller 12 includes one or more processors 52 and one or more memories 54 coupled to processors 52 . The memory 54 includes a ROM storing programs and the like, and a RAM as a work area. Processor 52 of controller 12 cooperates with programs contained in memory 54 to control engine 10 . The operation of the controller 12 will be detailed later.

FIG. 2 is a schematic diagram of the engine system 1 showing the first and second cylinders in longitudinal section. FIG. 3 is a schematic plan view of the first and second cylinders viewed from above. 2 and 3 show the C cylinder 30c and the A cylinder 30a as the first and second cylinders. Since the D cylinder 30d and the B cylinder 30b have the same configuration as the C cylinder 30c and the A cylinder 30a, illustration thereof is omitted.

Engine 10 includes cylinder block 60 , piston 62 , connecting rod 64 and cylinder head 66 . C cylinder 30 c and A cylinder 30 a are formed in cylinder block 60 . A piston 62 is housed in each cylinder. The piston 62 is connected to a crankshaft (not shown) via a connecting rod 64 .

The cylinder head 66 is arranged on the side of the cylinder block 60 opposite to the crankshaft. A cylinder head 66 is arranged on each cylinder so as to cover the upper opening of each cylinder, and is connected to the cylinder block 60 . The combustion chamber 68 is a space surrounded by the inner surface of the cylinder, the inner surface of the cylinder head 66 and the crown surface of the piston 62 .

The cylinder head 66 has an intake port 70 and an exhaust port 72 for each cylinder. Specifically, the intake port 70 of the C cylinder 30 c communicates with the combustion chamber 68 of the C cylinder 30 c through an opening 74 . The exhaust port 72 of the C-cylinder 30c communicates with the combustion chamber 68 of the C-cylinder 30c through an opening 76 . The intake port 70 of the A cylinder 30a communicates through an opening 74 with the combustion chamber 68 of the A cylinder 30a. The exhaust port 72 of the A cylinder 30 a communicates with the combustion chamber 68 of the A cylinder 30 a through an opening 76 .

The intake valve 40 is provided in the intake port 70 and opens and closes an opening 74 of the intake port 70 . When the opening 74 of the intake port 70 is opened by the intake valve 40 , air is introduced into the combustion chamber 68 through the intake port 70 . The exhaust valve 42 is provided in the exhaust port 72 and opens and closes an opening 76 of the exhaust port 72 . When the opening 76 of the exhaust port 72 is opened by the exhaust valve 42 , gas within the combustion chamber 68 is exhausted through the exhaust port 72 .

A connection port 32 is formed in the cylinder head 66 . The first valve 44 is provided on the C cylinder 30c side of the connection port 32 and opens and closes the opening 80 on the C cylinder 30c side. The second valve 46 is provided on the A cylinder 30a side of the connection port 32 and opens and closes the opening 82 on the A cylinder 30a side. As will be described later, when the first valve 44 and the second valve 46 are opened, exhaust gas from the C cylinder 30c, which is the first cylinder, is introduced through the connection port 32 into the combustion chamber 68 of the A cylinder 30a, which is the second cylinder. be.

As shown in FIG. 3, in the C cylinder 30c, one opening 74 of the intake port 70 and one opening 76 of the exhaust port 72 are provided. An opening 74 of the intake port 70 of the C cylinder 30c is provided eccentrically with respect to the central axis of the C cylinder 30c. An opening 76 of the exhaust port 72 of the C cylinder 30c is provided on the side opposite to the intake port 70 with the central axis of the C cylinder 30c interposed therebetween. Similarly, in the A cylinder 30a, one opening 74 of the intake port 70 and one opening 76 of the exhaust port 72 are provided. The opening 74 of the intake port 70 of the A cylinder 30a is provided eccentrically with respect to the central axis of the A cylinder 30a. The opening 76 of the exhaust port 72 of the A cylinder 30a is provided on the side opposite to the intake port 70 with the central axis of the A cylinder 30a interposed therebetween.

The opening 80 of the connection port 32 on the C-cylinder 30c side is arranged in the gap between the opening 74 of the intake port 70 and the opening 76 of the exhaust port 72 of the C-cylinder 30c, and is positioned closer to the A-cylinder 30a. The opening 82 of the connection port 32 on the side of the A cylinder 30a is arranged in the gap between the opening 74 of the intake port 70 and the opening 76 of the exhaust port 72 of the A cylinder 30a, and is located closer to the C cylinder 30c.

As shown in FIG. 2, the cylinder head 66 is provided with injectors 84 and spark plugs 86 for each cylinder. The injector 84 is arranged with the injection port directed toward the combustion chamber 68 . The injector 84 injects fuel such as gasoline into the combustion chamber 68 at a predetermined timing. The spark plug 86 is arranged with the electrode facing the combustion chamber 68 . The spark plug 86 ignites and burns the mixed gas of air and fuel in the combustion chamber 68 at a predetermined timing. Such combustion causes the piston 62 to reciprocate in the axial direction of the cylinder. The crankshaft rotates according to the reciprocating motion of piston 62 .

FIG. 4 is a diagram for explaining strokes in each cylinder. Each cylinder repeats an intake stroke, a compression stroke, an explosion stroke, and an exhaust stroke in this order. Each stroke is shifted in each cylinder so that the same stroke does not overlap in each cylinder.

Specifically, when the A cylinder 30a is on the intake stroke, the B cylinder 30b is on the power stroke, the C cylinder 30c is on the exhaust stroke, and the D cylinder 30d is on the compression stroke. When the A cylinder 30a is on the compression stroke, the B cylinder 30b is on the exhaust stroke, the C cylinder 30c is on the intake stroke, and the D cylinder 30d is on the explosion stroke. When the A cylinder 30a is in the explosion stroke, the B cylinder 30b is in the intake stroke, the C cylinder 30c is in the compression stroke, and the D cylinder 30d is in the exhaust stroke. When the A cylinder 30a is on the exhaust stroke, the B cylinder 30b is on the compression stroke, the C cylinder 30c is on the power stroke, and the D cylinder 30d is on the intake stroke.

That is, when the C cylinder 30c, which is the first cylinder, is in the exhaust stroke, the A cylinder 30a, which is the second cylinder, is in the intake stroke. Similarly, when the D cylinder 30d, which is the first cylinder, is in the exhaust stroke, the B cylinder 30b, which is the second cylinder, is in the intake stroke.

The control device 12 causes the valve mechanism 48 to open the first valve 44 and the second valve 46 when the first cylinder is in the exhaust stroke. Then, the exhaust gas from the first cylinder, which is on the exhaust stroke, is introduced through the connection port 32 into the second cylinder, which is on the intake stroke. The control device 12 can smoothly introduce the exhaust gas from the first cylinder into the second cylinder by controlling the second cylinder to be in the intake stroke when the first cylinder is in the exhaust stroke.

As shown in FIG. 2, the engine system 1 has an exhaust passage 90, a catalyst 92 and an exhaust port 94. As shown in FIG. The exhaust passage 90 is connected to the exhaust port 72 of the A cylinder 30a, which is the second cylinder. Although not shown, the exhaust passage 90 is also connected to the exhaust port 72 of the C cylinder 30c, which is the first cylinder. A catalyst 92 is provided in the exhaust flow path 90 . Specifically, the catalyst 92 is provided closer to the exhaust port 94 than the position where the exhaust passage 90 extending from the A cylinder 30a and the exhaust passage 90 extending from the C cylinder 30c join. Exhaust gas discharged from the exhaust port 72 of the A cylinder 30 a flows through the exhaust passage 90 and the catalyst 92 and is discharged from the exhaust port 94 . The catalyst 92 purifies the exhaust flowing through the exhaust passage 90 .

The engine system 1 has an air-fuel ratio sensor 100 and a water temperature sensor 102 . The air-fuel ratio sensor 100 is provided between the A cylinder 30 a and the catalyst 92 in the exhaust passage 90 . The air-fuel ratio sensor 100 detects the air-fuel ratio of the exhaust flowing through the exhaust passage 90 . A water temperature sensor 102 is provided in a flow path of cooling water for cooling the engine 10 and detects the water temperature, which is the temperature of the cooling water.

Control device 12 acquires the detection results of air-fuel ratio sensor 100 and water temperature sensor 102 . The control device 12 controls the injection amount of fuel in the injector 84 based on the air-fuel ratio acquired from the air-fuel ratio sensor 100 . Control device 12 estimates the temperature of catalyst 92 based on the water temperature obtained from water temperature sensor 102 . Henceforth, the temperature of the catalyst 92 may be called catalyst temperature.

The control device 12 switches the operating mode of the engine 10 between the normal operating mode and the special operating mode according to the estimated catalyst temperature. The normal operation mode is an operation mode in which the engine 10 is operated without supplying exhaust gas from the first cylinder to the second cylinder. The special operation mode is an operation mode in which the engine 10 is operated while exhaust gas from the first cylinder is supplied to the second cylinder. Hereinafter, the operation of the engine 10 in the normal operation mode may be called normal operation, and the operation of the engine 10 in the special operation mode may be called special operation.

FIG. 5 is a diagram for explaining special actions. In FIG. 5, the C cylinder 30c and the A cylinder 30a are shown as the first cylinder and the second cylinder. The special operation is an operation of opening and closing the first valve 44 and the second valve 46 by the valve mechanism 48 according to the strokes of the first cylinder and the second cylinder, respectively, and supplying exhaust gas from the first cylinder to the second cylinder. is.

Although not shown, the valve mechanism 48 includes a valve stop mechanism capable of maintaining the exhaust valve 42 of the first cylinder in a closed state. The stop valve mechanism may be, for example, a mechanism that stops the rotation of the cam, a mechanism that causes the cam to miss the rocker arm, or any known technique can be applied. .

In the special operation, the opening 76 of the exhaust port 72 of the first cylinder is closed by the valve stopping mechanism of the valve mechanism 48, as indicated by the cross mark A10 in FIG. On the other hand, the opening 74 of the intake port 70 of the first cylinder and the opening 80 of the connection port 32 on the first cylinder side are opened and closed according to the stroke of the first cylinder. The opening 74 of the intake port 70 of the second cylinder, the opening 76 of the exhaust port 72 of the second cylinder, and the opening 82 of the connection port 32 on the second cylinder side are opened and closed according to the stroke of the second cylinder. be.

When the first cylinder is in the intake stroke, air is introduced into the first cylinder through the intake port 70 as indicated by the solid arrow A12. When the first cylinder enters the exhaust stroke, the exhaust gas from the first cylinder is supplied to the second cylinder through the connection port 32, as indicated by the dashed-dotted arrow A14. Further, when the first cylinder is on the exhaust stroke, the second cylinder is on the intake stroke. When the second cylinder is in the intake stroke, the exhaust gas from the first cylinder is supplied to the second cylinder as described above, and air is introduced into the second cylinder through the intake port 70 as indicated by the solid line arrow A16. be. When the second cylinder enters the exhaust stroke, the exhaust of the second cylinder is discharged through the exhaust port 72 as indicated by the dashed-dotted arrow A18. Thus, in the special operation, the first cylinder and the second cylinder are linked with each other.

Generally, before the engine 10 is started, the catalyst temperature is below a predetermined temperature. The predetermined temperature is set, for example, to the lower limit temperature at which the catalyst 92 is activated. After a predetermined time has passed since the engine 10 started, the catalyst 92 is heated by the exhaust gas from the engine 10, and the catalyst temperature reaches a predetermined temperature or higher. Here, the period from when the engine 10 is started until the temperature of the catalyst becomes equal to or higher than a predetermined temperature may be called a cold state of the engine 10 . The special operation is performed when the engine 10 is in a cold state in which the catalyst temperature is below a predetermined temperature. That is, the special operation is performed when the catalyst 92 is not activated.

By the way, when the catalyst temperature is less than the predetermined temperature, the temperature of the wall surface of the combustion chamber 68 of each cylinder is relatively low because the warm-up of the engine 10 is not completed. If the temperature of the wall surface of the combustion chamber 68 of the cylinder is low, the fuel adhering to the wall surface is difficult to vaporize, and the fuel on the wall surface is not sufficiently mixed with air, resulting in incomplete combustion of the fuel on the wall surface. Hydrocarbons (HC), carbon monoxide (CO) and soot (PM or PN) are then generated. Hydrocarbons, carbon monoxide, and soot are environmental load components that may impact the environment when discharged into the atmosphere.

Further, when fuel is burned in a stoichiometric atmosphere and the combustion temperature is relatively high, nitrogen oxides (NOx) are generated. Nitrogen oxides are environmental load components that may impose a load on the environment when discharged into the atmosphere.

Here, as a comparative example, there is an engine system in which the exhaust gas from the first cylinder is not supplied to the second cylinder and the exhaust gas from the first cylinder is discharged from the exhaust port 72 when the engine is cold. Since the catalyst 92 is not activated when the engine is cold, in the engine system of this comparative example, environmental load components such as hydrocarbons, carbon monoxide, soot, and nitrogen oxides may be discharged into the atmosphere. be.

On the other hand, the control device 12 of the engine system 1 of the present embodiment controls the engine 10 with a special operation when the engine 10 is cold. In the special operation, the control device 12 controls the engine 10 so that the first cylinder burns fuel in a rich atmosphere and the second cylinder burns fuel in a stoichiometric atmosphere. A rich atmosphere has a greater proportion of fuel than a stoichiometric atmosphere. Then, in the special operation, the control device 12 introduces the exhaust gas from the first cylinder into the second cylinder through the connection port 32 .

During the special operation, the control device 12 causes the injector 84 to inject fuel so that the inside of the first cylinder is in a rich atmosphere. As a result, in the first cylinder, hydrocarbons, carbon monoxide, and soot are produced not only by the incomplete combustion of the fuel that reaches the wall surface of the combustion chamber 68 of the first cylinder, but also by the combustion of the fuel that has not reached the wall surface. likely to occur. Hydrocarbons, carbon monoxide and soot are also unburned fuels.

However, since the inside of the first cylinder is in a rich atmosphere, nitrogen oxides are less likely to be generated in the first cylinder. Therefore, exhaust gas containing a large amount of unburned fuel such as hydrocarbons, carbon monoxide, and soot and having a reduced content of nitrogen oxides is introduced from the first cylinder to the second cylinder.

During the special operation, the control device 12 does not cause the injector 84 of the second cylinder to inject fuel, and uses the unburned fuel supplied from the first cylinder to create a stoichiometric atmosphere in the second cylinder. The unburned fuel supplied from the first cylinder is sufficiently vaporized. Therefore, the supplied unburned fuel can be completely burned in the second cylinder. Further, by preventing the injector 84 of the second cylinder from injecting fuel, it is possible to suppress the generation of new unvaporized fuel. Therefore, incomplete combustion of fuel can be suppressed in the second cylinder.

In addition, the exhaust gas from the first cylinder contains a large amount of inert gas such as the unburned fuel described above. In the second cylinder, due to the inert gas in the exhaust of the first cylinder, the combustion temperature is lowered compared to a mode in which the exhaust of the first cylinder is not supplied. Although the inside of the second cylinder is in a stoichiometric atmosphere, the combustion temperature inside the second cylinder is lowered, so that the generation of nitrogen oxides can be suppressed in the second cylinder.

Due to these, exhaust gas in which the contents of hydrocarbons, carbon monoxide, soot and nitrogen oxides are suppressed is discharged from the second cylinder to the exhaust passage 90 .

During the special operation, the catalyst temperature is below the predetermined temperature and the catalyst 92 is not activated. However, since the exhaust gas in which the contents of hydrocarbons, carbon monoxide, soot and nitrogen oxides are suppressed flows through the exhaust passage 90, it is discharged to the atmosphere from the exhaust port 94 even if the catalyst 92 is not activated. Environmental load components can be suppressed.

The control device 12 controls the fuel injection amount of the injector 84 of the first cylinder so that the air-fuel ratio detected by the air-fuel ratio sensor 100 becomes stoichiometric. Thereby, the second cylinder is controlled to a stoichiometric atmosphere. In addition, since the second cylinder is brought into a stoichiometric atmosphere by the exhaust gas from the first cylinder, the control device 12 controls the first cylinder so as to produce a rich atmosphere.

Note that the control device 12 controls the injector 84 of the second cylinder so as not to inject fuel. However, on condition that the first cylinder is in a rich atmosphere and the second cylinder is in a stoichiometric atmosphere, the control device 12 may cause the injector 84 of the second cylinder to inject fuel. Since the exhaust gas of the first cylinder is supplied to the second cylinder, even if fuel is injected into the second cylinder, relatively little fuel is injected into the second cylinder. Therefore, in this mode, incomplete combustion in the second cylinder can be suppressed compared to the mode in which the exhaust gas from the first cylinder is not supplied to the second cylinder. As a result, even in this aspect, when the engine 10 is in a cold state, it is possible to suppress the environmental load components discharged into the atmosphere from the exhaust port 94 .

FIG. 6 is a diagram for explaining normal operation. In FIG. 6, the C cylinder 30c and the A cylinder 30a are shown as the first cylinder and the second cylinder. The normal operation is an operation in which the first valve 44 and the second valve 46 are closed by the valve mechanism 48 and exhaust gas from the first cylinder is not supplied to the second cylinder.

Although illustration is omitted, the valve stop mechanism of the valve mechanism is configured to be able to maintain the first valve 44 and the second valve 46 in a closed state, like the exhaust valve 42 of the first cylinder.

In normal operation, the opening 80 on the side of the first cylinder and the opening 82 on the side of the second cylinder of the connection port 32 are closed by the valve stop mechanism of the valve mechanism 48, as indicated by the cross mark A20 in FIG. On the other hand, the opening 74 of the intake port 70 of the first cylinder and the opening 76 of the exhaust port 72 of the first cylinder are opened and closed according to the stroke of the first cylinder. The opening 74 of the intake port 70 of the second cylinder and the opening 76 of the exhaust port 72 of the second cylinder are opened and closed according to the stroke of the second cylinder.

When the first cylinder is in the intake stroke, air is introduced into the first cylinder through the intake port 70 as indicated by the solid line arrow A22. When the first cylinder enters the exhaust stroke, the exhaust from the first cylinder is discharged through the exhaust port 72 as indicated by the dashed-dotted arrow A24. Further, when the second cylinder is in the intake stroke, air is introduced into the second cylinder through the intake port 70 as indicated by the solid line arrow A26. When the second cylinder enters the exhaust stroke, the exhaust of the second cylinder is discharged through the exhaust port 72 as indicated by the dashed-dotted arrow A28. Thus, in normal operation, the first cylinder and the second cylinder operate independently of each other.

Also, the normal operation is performed when the catalyst temperature is equal to or higher than the predetermined temperature. That is, normal operation occurs when the catalyst is activated.

In the special operation, the injector 84 of the second cylinder is not injected with fuel, but in the normal operation, the injector 84 of the second cylinder is injected with fuel, and the fuel injected from the injector 84 is burned.

In the special operation, the first cylinder is in a rich atmosphere and the second cylinder is in a stoichiometric atmosphere. It can be used as atmosphere. Since the normal operation is performed while the catalyst 92 is activated, even if the environmental load component is discharged from the first cylinder or the second cylinder in the normal operation, the environmental load component is purified by the catalyst 92 .

FIG. 7 is a time chart for explaining the time transition of the control of the engine 10 by the control device 12. As shown in FIG. A solid line A30 in FIG. 7 indicates an example of the time transition of the catalyst temperature. A dashed-dotted line A32 in FIG. 7 indicates the predetermined temperature Tth, which is a threshold for switching the operating mode of the engine 10 .

Assume that the engine 10 is started at timing t0 in FIG. At timing t0, the catalyst temperature is T0, which is lower than the predetermined temperature Tth, so the catalyst 92 is not activated. Further, since the catalyst temperature is lower than the predetermined temperature Tth at the timing t0, the control device 12 sets the operation mode of the engine 10 to the special operation mode. Then, the first cylinder is controlled to be in a rich atmosphere and the second cylinder is controlled to be in a stoichiometric atmosphere. Since the engine 10 is controlled by the special operation, even if the catalyst 92 is not activated, it is possible to suppress the environmental load component from being discharged to the atmosphere from the exhaust port 94 .

After timing t0, the exhaust gas from the engine 10 gradually heats the catalyst 92. As shown in FIG. Assume that the catalyst temperature reaches or exceeds a predetermined temperature Tth at timing t1. When the catalyst temperature reaches or exceeds a predetermined temperature, the catalyst 92 is activated. At timing t1 when the catalyst temperature reaches or exceeds the predetermined temperature Tth, the control device 12 switches the operation mode of the engine 10 from the special operation mode to the normal operation mode. The atmosphere of the first cylinder and the second cylinder in normal operation can be any atmosphere. Since the catalyst 92 is activated, the environmental load components discharged from the engine 10 are purified by the catalyst 92 .

FIG. 8 is a flow chart for explaining the operation flow of the control device 12. As shown in FIG. While the engine 10 is stopped, the control device 12 executes the series of processes shown in FIG. 8 at predetermined interrupt timings that occur in predetermined control cycles.

At a predetermined interrupt timing, the control device 12 determines whether or not the engine 10 has been started (S10). If the engine 10 is stopped (NO in S10), the control device 12 terminates the series of processes.

When the engine 10 is started (YES in S10), the control device 12 derives the catalyst temperature based on the water temperature detected by the water temperature sensor 102 (S11). A temperature sensor that directly detects the catalyst temperature may be provided in the catalyst 92, and the controller 12 may directly acquire the catalyst temperature from the temperature sensor.

Next, the control device 12 determines whether or not the catalyst temperature is equal to or higher than a predetermined temperature (S12). If the catalyst temperature is less than the predetermined temperature (NO in S12), the control device 12 causes the valve mechanism 48 to close the exhaust valve 42 of the first cylinder (S13), and causes the engine 10 to perform a special operation (S14). . Then, the control device 12 returns to step S11 to again derive the catalyst temperature and compare the catalyst temperatures. As a result, the special operation is continuously performed until the catalyst temperature reaches or exceeds the predetermined temperature. In the special operation, the first cylinder is set to a rich atmosphere, the second cylinder is set to a stoichiometric atmosphere, and exhaust gas from the first cylinder is supplied to the second cylinder.

In step S12, when the catalyst temperature is equal to or higher than the predetermined temperature (YES in S12), the control device 12 cancels the closed state of the exhaust valve 42 of the first cylinder (S15). As a result, the exhaust valve 42 of the first cylinder is opened and closed according to the stroke of the first cylinder. Next, the control device 12 closes the first valve 44 and the second valve 46 by the valve mechanism 48 (S16), normally operates the engine 10 (S17), and ends the series of processes.

As described above, in the engine system 1 of the present embodiment, the processor 52 causes the first cylinder to burn fuel in a rich atmosphere and the second cylinder to burn fuel in a stoichiometric atmosphere when the engine 10 is cold. , executes the processing for controlling the engine 10 . Further, when the engine 10 is cold, the processor 52 controls the second cylinder to the intake stroke when the first cylinder is in the exhaust stroke, and introduces the exhaust gas from the first cylinder into the second cylinder through the connection port 32. to run. As a result, the unburned fuel contained in the exhaust gas from the first cylinder is burned in the second cylinder, and the generation of nitrogen oxides in the second cylinder is suppressed. Ejected.

Therefore, according to the engine system 1 of the present embodiment, even if the catalyst 92 is not activated, it is possible to suppress the emission of environmental load components into the atmosphere.

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

For example, in the above embodiment, both the right bank 20 and the left bank 22 of the horizontally opposed engine are provided with the first cylinder, the second cylinder and the connection port 32 . However, only one of the right bank 20 and the left bank 22 of the horizontally opposed engine may be provided with the first cylinder, the second cylinder and the connection port 32 . Further, the engine 10 is not limited to a horizontally opposed engine, and may be any type of engine such as a V-type engine.

Further, in the above embodiment, the first cylinder is provided with one intake port 70, one exhaust port 72 and one connection port 32, respectively. However, two intake ports 70, one exhaust port 72 and one connection port 32 may be provided in the first cylinder. Further, in the above embodiment, the second cylinder is provided with one intake port 70, one exhaust port 72, and one connection port 32, respectively. However, one intake port 70, two exhaust ports 72 and one connection port 32 may be provided in the second cylinder.

1 Engine system 10 Engine 12 Control device 20 Right bank 22 Left bank 30a A cylinder 30b B cylinder 30c C cylinder 30d D cylinder 32 Connection port 44 First valve 46 Second valve 48 Valve mechanism 52 Processor 54 Memory 72 Exhaust port 90 Exhaust Channel 92 Catalyst

Claims (5)

an engine having a first cylinder, a second cylinder, and a connection port that connects the first cylinder and the second cylinder in series;
a control device that controls the engine;
with
The control device is
one or more processors;
one or more memories connected to the processor;
has
The processor
controlling the engine so that when the engine is cold, fuel is burned in a rich atmosphere in the first cylinder and fuel is burned in a stoichiometric atmosphere in the second cylinder;
controlling the second cylinder to an intake stroke when the first cylinder is in an exhaust stroke, and introducing exhaust gas from the first cylinder into the second cylinder through the connection port;
An engine system that performs processing, including The processor
controlling the engine to inject fuel into the first cylinder and not to inject fuel into the second cylinder when the engine is cold;
2. The engine system according to claim 1, which performs a process comprising: A catalyst provided in an exhaust passage connected to the exhaust port of the second cylinder,
The processor
Depending on the temperature of the catalyst, the operation mode of the engine may be changed to a normal operation mode in which the engine is operated without supplying exhaust gas from the first cylinder to the second cylinder, or a normal operation mode in which the exhaust gas from the first cylinder is supplied to the second cylinder. switching between special operating modes that operate the engine while feeding two cylinders;
3. The engine system according to claim 1 or 2, which performs a process including: a first valve capable of opening and closing an opening of the connection port on the first cylinder side;
a second valve capable of opening and closing an opening of the connection port on the second cylinder side;
a valve mechanism that opens and closes the first valve and the second valve;
further comprising
The processor
If the temperature of the catalyst is less than a predetermined temperature, the special operation mode is executed, and the first valve and the second valve are operated by the valve mechanism according to the strokes of the first cylinder and the second cylinder, respectively. to operate the engine while supplying exhaust gas from the first cylinder to the second cylinder;
If the temperature of the catalyst is equal to or higher than the predetermined temperature, the normal operation mode is executed, the first valve and the second valve are closed by the valve mechanism, and the exhaust gas from the first cylinder is diverted to the second valve. operating the engine normally without feeding the cylinders;
4. The engine system according to claim 3, which performs a process comprising: The engine is a horizontally opposed engine,
5. The engine system according to any one of claims 1 to 4, wherein said first cylinder and said second cylinder are provided in one or both of left bank and right bank of said horizontally opposed engine.

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