JP7635815B1 - Playback System - Google Patents

Abstract

To supply fuel to an exhaust pipe with a simple configuration.
[Solution] The regeneration system S is provided in an exhaust pipe 3 that discharges exhaust from an engine 1 to the outside, and has a filter 35 that collects substances contained in the exhaust, an exhaust valve control unit 623 that opens the exhaust valve 42 of a first group of cylinders 21 during the compression stroke of some of the multiple cylinders of the engine 1, and an injection control unit 624 that injects a second injection amount of fuel into the combustion chamber 242 of the first group of cylinders 21 when the exhaust valve 42 is open during the compression stroke, the second injection amount being smaller than the first injection amount of fuel injected into the combustion chamber 242 of the first group of cylinders 21 when the exhaust valve 42 is closed during the compression stroke of the first group of cylinders 21.
[Selected figure] Figure 3

Description

The present invention relates to a regeneration system that regenerates a filter that captures substances contained in exhaust gas.

Technology is known for regenerating DPFs (diesel particulate filters) that capture soot and other particles contained in exhaust gas. Patent Document 1 discloses a technology in which, when a predetermined amount of accumulated soot and other particles is reached, fuel (diesel oil) is directly injected into the exhaust pipe from an injection section upstream of the DPF, and the fuel is combusted near the filter to incinerate the soot and other particles captured on the filter, thereby regenerating the filter.

JP 2006-233936 A

However, in order to supply fuel into the exhaust pipe upstream of the filter, an injection unit that injects fuel into the exhaust pipe, as well as piping and a pump that supply fuel to the injection unit, were required, making the configuration for supplying fuel into the exhaust pipe complex.

Therefore, the present invention was made in consideration of these points, and aims to supply fuel to the exhaust pipe with a simple configuration.

In one aspect of the present invention, a regeneration system is provided that includes a filter that is provided in an exhaust pipe that discharges engine exhaust to the outside and that collects substances contained in the exhaust, an exhaust valve control unit that controls the opening and closing of exhaust valves of some of the cylinders among a plurality of cylinders of the engine during the compression stroke of the some of the cylinders, and an injection control unit that controls an injection unit that injects fuel into the combustion chambers of the some of the cylinders, and when the exhaust valve control unit removes the substances collected in the filter, the exhaust valve control unit opens the exhaust valve during the compression stroke of the some of the cylinders, and the injection control unit injects a second injection amount of fuel that is smaller than the first injection amount of fuel injected into the combustion chambers of the some of the cylinders when the exhaust valve is open during the compression stroke of the some of the cylinders.

The injection control unit may inject the second injection amount of fuel into the combustion chamber of the part of the cylinders with the exhaust valve open during the compression stroke at the same timing as when fuel is injected into the combustion chamber of the part of the cylinders with the exhaust valve closed during the compression stroke.

The system may have a turbine provided in the exhaust pipe of a turbocharger that compresses fresh air supplied to the engine, a bypass pipe capable of supplying exhaust from the partial cylinders to a position downstream of the turbine in the exhaust pipe from between the engine and the turbine in the exhaust pipe, and a flow passage control unit that supplies exhaust from the partial cylinders to the bypass pipe when fuel is injected into the combustion chamber of the partial cylinder with the exhaust valve open during the compression process.

The exhaust pipe includes a first pipe that supplies exhaust from the selected cylinders to the turbine, and a second pipe that supplies exhaust from other cylinders than the selected cylinders to the turbine, and the bypass pipe may supply exhaust from the selected cylinders from between the engine and the turbine in the first pipe to a position downstream of the turbine in the exhaust pipe.

The engine has a first recirculation line that recirculates the exhaust gas from the selected cylinders to the intake line of the engine, and a second recirculation line that recirculates the exhaust gas from the other cylinders to the intake line, and when fuel is injected into the combustion chamber of the selected cylinder with the exhaust valve open during the compression stroke, the flow path control unit may supply a portion of the exhaust gas from the other cylinders to the second recirculation line to recirculate it to the intake line, and may not supply the exhaust gas from the selected cylinders to the first recirculation line.

When the injection control unit injects fuel into the combustion chamber of the partial cylinder with the exhaust valve open during the compression stroke, the injection control unit may inject a fourth injection amount of fuel into the combustion chamber of the other cylinder, the fourth injection amount being greater than a third injection amount of fuel injected into the combustion chamber of the other cylinder with the exhaust valve of the partial cylinder closed during the compression stroke of the partial cylinder.

When the exhaust valve opens during the compression stroke of the partial cylinder, the injection control unit may inject the fourth injection amount of fuel, which is greater than the third injection amount by an amount corresponding to the load applied to the engine when the exhaust valve is open during the compression stroke of the partial cylinder, into the combustion chamber of the other cylinder.

The exhaust valve control unit may open the exhaust valve during the compression stroke of some of the cylinders when removal of the material trapped in the filter is necessary, the engine speed is equal to or lower than a predetermined speed, and the commanded injection amount of fuel to be injected into the combustion chamber is equal to or lower than a predetermined value.

The present invention has the advantage of being able to supply fuel to the exhaust pipe with a simple configuration.

FIG. 1 is a diagram for explaining the configuration of a playback system. FIG. 2 is a schematic diagram of an engine cylinder. FIG. 2 is a diagram for explaining the configuration of an engine control device. FIG. 2 is a diagram for explaining the flow of exhaust gas discharged from a cylinder. 10 is a flowchart showing an example of a process flow for regenerating a filter.

The regeneration system S is a system for removing substances deposited on a filter 35 that collects substances contained in the exhaust gas of the engine 1. The configuration of the regeneration system S will be described with reference to Figures 1, 2, and 3. Figure 1 is a diagram for explaining the configuration of the regeneration system S. Figure 2 is a schematic diagram of the cylinders of the engine 1. Figure 3 is a diagram for explaining the configuration of the engine control device 6. The regeneration system S has an engine 1, a plurality of cylinders 2, an exhaust pipe 3, an engine control device 6, an intake pipe 12, and a filter 35. Each of the plurality of cylinders 2 has an exhaust valve 42 and an injection unit 43 that injects fuel into the combustion chamber 242 of the cylinder 2.

Engine 1 is an internal combustion engine that burns and expands a mixture of fuel and fresh air (air) to generate power. Engine 1 is, for example, a diesel engine mounted on an automobile or a ship. The multiple cylinders 2 include four cylinders: a first cylinder 211, a second cylinder 212, a third cylinder 213, and a fourth cylinder 214. Hereinafter, when there is no need to distinguish between the first cylinder 211, the second cylinder 212, the third cylinder 213, and the fourth cylinder 214, they will be referred to as cylinders 2. The first cylinder 211 and the fourth cylinder 214, which are some of the multiple cylinders 2 of engine 1, are a first cylinder group 21. The second cylinder 212 and the third cylinder 213, which are other cylinders different from the some of the multiple cylinders 2 of engine 1, are a second cylinder group 22.

The cylinder 2 has an intake valve 41, an exhaust valve 42, an injection unit 43, and a piston 241. The intake valve 41 and the exhaust valve 42 are closed at the start of the operating cycle of the engine 1. First, when the piston 241 descends, the intake valve 41 opens, and fresh air is drawn into the cylinder 2 (intake stroke). Next, when the piston 241 reaches the bottom dead center, the intake valve 41 closes, and when the piston 241 ascends to the top dead center, the air is compressed (compression stroke). Next, fuel is injected by the injection unit 43, and the fuel mixed with the compressed and heated air is burned, and the expanded combustion gas pushes the piston 241 down to the bottom dead center (combustion stroke). Then, due to inertia and expansion in other cylinders 2, when the piston 241 ascends again to the top dead center, the exhaust valve 42 opens, and the combustion gas is pushed out of the cylinder 2 and discharged as exhaust gas into the exhaust pipe 3 (exhaust stroke).

The intake pipe 12 is a pipe that supplies fresh air to the engine 1. The intake pipe 12 is a pipe that branches to correspond to each cylinder 2 and supplies fresh air to each cylinder 2. An intercooler 143 is provided in the intake pipe 12. The intercooler 143 cools the fresh air supplied to the engine 1. The intercooler 143 is a heat exchanger that cools the fresh air by exchanging heat between the fresh air and the cooling water of the engine 1 or outside air.

The exhaust pipe 3 is a pipe that discharges the exhaust gas of the engine 1 to the outside. The exhaust pipe 3 is provided with a turbine 162 of the supercharger 16 that compresses fresh air supplied to the engine 1. The turbine 162 rotates when the exhaust gas passes through it. The turbine 162 is connected to a compressor 161 of the supercharger 16. The compressor 161 is provided in the intake pipe 12. The compressor 161 rotates in conjunction with the rotation of the turbine 162 to compress and supercharge the fresh air.

The exhaust pipe 3 has a first pipe 31, a second pipe 32, and a third pipe 33. The first pipe 31 is connected to the first cylinder group 21 and is a pipe for supplying the exhaust of the first cylinder group 21 to the turbine 162. The second pipe 32 is connected to the second cylinder group 22 and is a pipe for supplying the exhaust of the second cylinder group 22 to the turbine 162. The third pipe 33 is a pipe for discharging the exhaust that has passed through the turbine 162 to the outside.

The first return pipe 131 connects the first pipe 31 and the intake pipe 12, and is a pipe for returning the exhaust gas of the first cylinder group 21 to the intake pipe 12. The first return pipe 131 is provided with an exhaust cooler 141. The exhaust cooler 141 is a heat exchanger that cools the exhaust gas of the first cylinder group 21 by exchanging heat between the exhaust gas of the first cylinder group 21 and the cooling water of the engine 1 or the outside air. A first control valve 151 is provided between the intake pipe 12 and the exhaust cooler 141 in the first return pipe 131. The first control valve 151 adjusts the flow rate of the exhaust gas of the first cylinder group 21 that flows into the intake pipe 12. The first control valve 151 adjusts the flow rate of the exhaust gas of the first cylinder group 21 that passes through the first control valve 151 by operating an adjustment valve that adjusts the flow area of the flow path under the control of the engine control device 6, thereby adjusting the flow area of the flow path.

The second recirculation pipe 132 connects the second pipe 32 and the intake pipe 12, and is a pipe for recirculating the exhaust gas of the second cylinder group 22 to the intake pipe 12. The second recirculation pipe 132 is provided with an exhaust cooler 142. The exhaust cooler 142 is a heat exchanger that cools the exhaust gas of the second cylinder group 22 by exchanging heat between the exhaust gas of the second cylinder group 22 and the cooling water of the engine 1 or the outside air. A second control valve 152 is provided between the intake pipe 12 and the exhaust cooler 142 in the second recirculation pipe 132. The second control valve 152 adjusts the flow rate of the exhaust gas of the second cylinder group 22 that flows into the intake pipe 12. The second control valve 152 adjusts the flow rate of the exhaust gas of the second cylinder group 22 that passes through the second control valve 152 by operating an adjustment valve that adjusts the flow area of the flow path under the control of the engine control device 6, thereby adjusting the flow area of the flow path.

The third pipe 33 is provided with a purification device 34 and a filter 35. The purification device 34 is provided between the turbine 162 and the filter 35. The purification device 34 purifies the exhaust gas from the engine 1. The purification device 34 is, for example, a diesel oxidation catalyst (DOC), but is not limited to this.

The filter 35 is provided downstream of the purification device 34 in the third pipe 33. The filter 35 is, for example, a DPD (diesel particulate diffuser). The filter 35 captures substances contained in the exhaust gas. The substances contained in the exhaust gas are, for example, particulate matter, specifically soot. If the amount of substances captured by the filter 35 exceeds the allowable amount that the filter 35 can capture, the collection performance of the filter 35 decreases. Therefore, if the amount of substances captured by the filter 35 exceeds the allowable amount, it is necessary to execute regeneration control to remove the substances captured by the filter 35 and regenerate the collection performance.

The bypass line 36 is a line that can supply the exhaust of the first cylinder group 21 from between the engine 1 and the turbine 162 in the exhaust line 3 to downstream of the turbine 162 in the exhaust line 3. Specifically, the bypass line 36 connects the first line 31 and the third line, and supplies the exhaust of the first cylinder group 21 from between the engine 1 and the turbine 162 in the first line to downstream of the turbine 162 in the exhaust line 3. In other words, the bypass line 36 causes the exhaust of the first cylinder group 21 to bypass (bypass) the turbine 162.

The three-way valve 153 is provided at a branching point where the bypass line 36 branches off from the first line 31. The three-way valve 153 switches whether or not the exhaust gas from the first cylinder group 21 is caused to bypass the turbine 162. Specifically, the three-way valve 153 switches whether or not the exhaust gas from the first cylinder group 21 is supplied to the turbine 162, or whether or not the exhaust gas from the first cylinder group 21 is supplied to the bypass line 36.

The engine control device 6 is an ECU (Electronic Control Unit) that controls the engine 1. When regeneration control of the filter 35 is necessary, the engine control device 6 supplies unburned fuel to the exhaust pipe 3 and burns it near the filter 35, thereby burning and removing the substances captured by the filter 35.
A specific configuration of the engine control device 6 will now be described.

The engine control device 6 has a memory unit 61 and a control unit 62. The memory unit 61 is a storage medium including a ROM (Read Only Memory), a RAM (Random Access Memory), a hard disk, etc. The memory unit 61 stores the programs executed by the control unit 62.

The control unit 62 is a computational resource including a processor such as a CPU (Central Processing Unit). The control unit 62 executes the programs stored in the memory unit 61 to realize the functions of an acquisition unit 621, a determination unit 622, an exhaust valve control unit 623, an injection control unit 624, and a flow path control unit 625.

The acquisition unit 621 acquires information from the sensor group 11 that detects information related to the regeneration system S. For example, the sensor group 11 includes a sensor that detects the pressure upstream and downstream of the filter 35 in the third pipeline 33. The acquisition unit 621 acquires the pressure upstream and downstream of the filter 35 from the sensor group 11. The sensor group 11 also includes a sensor that acquires the rotation speed of the engine 1, and a sensor that acquires the temperature of the coolant for the engine 1. The acquisition unit 621 acquires the rotation speed of the engine 1 and the temperature of the coolant for the engine 1 from the sensor group 11.

The acquisition unit 621 acquires a command injection amount of fuel to be injected into the combustion chamber 242. For example, the acquisition unit 621 acquires a command injection amount corresponding to an operation amount of an operation unit that controls the output of the engine 1. As a specific example, when the engine 1 is mounted on a vehicle, the acquisition unit 621 acquires a larger command injection amount as the depression amount of the accelerator pedal, which is the operation unit, increases. The acquisition unit 621 may also acquire a command injection amount corresponding to a required torque for the engine 1. In this case, the acquisition unit 621 acquires a larger command injection amount as the required torque increases.

The determination unit 622 determines whether regeneration control is necessary to remove the substances trapped in the filter 35. The determination unit 622 determines whether regeneration control is necessary by determining whether the amount of substances trapped by the filter 35 exceeds the allowable amount. When the amount of substances trapped by the filter 35 exceeds the allowable amount, it becomes difficult for the exhaust gas to pass through the filter 35, so the pressure of the exhaust gas flowing upstream of the filter 35 increases and the pressure of the exhaust gas flowing downstream of the filter 35 decreases. Therefore, when the amount of substances trapped by the filter 35 exceeds the allowable amount, the difference between the pressures of the two exhaust gases increases. Therefore, the determination unit 622 determines whether the amount of substances trapped by the filter 35 exceeds the allowable amount based on the pressure difference between the exhaust gas pressure upstream of the filter 35 and the exhaust gas pressure downstream of the filter 35, and determines whether regeneration control is necessary.

If the pressure difference is less than a predetermined pressure, the determination unit 622 determines that the amount of material captured by the filter 35 does not exceed the allowable amount, and that regeneration control is unnecessary. The predetermined pressure may be determined based on the performance and specifications of the filter 35 and on experiments. If the pressure difference is equal to or greater than the predetermined pressure, the exhaust valve control unit 623 determines that the amount of material captured by the filter 35 exceeds the allowable amount, and that regeneration control is necessary.

The exhaust valve control unit 623 controls the opening and closing of the exhaust valves 42 of the multiple cylinders 2. The exhaust valve control unit 623 controls the opening and closing of each of the exhaust valves 42 of the multiple cylinders 2 according to the process of the operating cycle of the engine 1. For example, when regeneration control of the filter 35 is not required, the exhaust valve control unit 623 closes the exhaust valves 42 of the first cylinder group 21 during the compression process of the first cylinder group 21. In the following description, the first cylinder group 21 in which the exhaust valves 42 are closed during the compression process may be referred to as the first cylinder group 21 during normal operation.

When regeneration control is necessary, the exhaust valve control unit 623 opens the exhaust valve 42 of the first cylinder group 21 (the first cylinder 211 and the fourth cylinder 214) during the compression stroke of the first cylinder group 21. Specifically, when regeneration control is necessary and the substances captured in the filter 35 are to be removed, the exhaust valve control unit 623 opens the exhaust valve 42 of the first cylinder group 21 during the compression stroke of the first cylinder group 21. In this case, the exhaust valve control unit 623 closes the exhaust valve 42 of the second cylinder group 22 (the second cylinder 212 and the third cylinder 213) during the compression stroke of the second cylinder group 22. In the following description, opening the exhaust valve 42 of the first cylinder group 21 during the compression stroke of the first cylinder group 21 may be referred to as compressing and releasing the first cylinder group 21. In addition, the first cylinder group 21 in which the exhaust valve 42 of the first cylinder group 21 is open during the compression stroke may be referred to as the first cylinder group 21 during compression and release.

The injection control unit 624 controls each injection unit 43 of the first cylinder group 21 and the second cylinder group 22 to control the injection of fuel into the combustion chamber 242 of the first cylinder group 21 and the second cylinder group 22. For example, the injection control unit 624 controls the injection unit 43 to inject fuel into the combustion chamber 242 of the first cylinder group 21 during compression release. In other words, the injection control unit 624 injects fuel into the combustion chamber 242 of the first cylinder group 21 where the temperature of the mixture does not reach a combustible temperature due to the exhaust valve 42 opening during the compression stroke.

When injecting fuel into the combustion chamber 242 of the first cylinder group 21 during compression release, the injection control unit 624 injects a second injection amount of fuel that is smaller than the first injection amount. The first injection amount is the amount of fuel injected into the combustion chamber 242 of the first cylinder group 21 during normal operation. The injection control unit 624 injects the second injection amount of fuel into the combustion chamber 242 of the first cylinder group 21 during compression release at the same timing as the timing of injecting fuel into the combustion chamber 242 of the first cylinder group 21 during normal operation. In other words, when injecting fuel into the first cylinder group 21 during compression release, the injection control unit 624 injects fuel N into the combustion chamber 242 of the first cylinder group 21 during compression release when the piston 241 is near top dead center, as in normal operation (see FIG. 2).

The combustion chamber 242 is designed to generate an airflow that suppresses the adhesion of the fuel N injected during the compression stroke to the inner wall, but is not designed assuming that the fuel N will be injected during the exhaust stroke. Therefore, the airflow generated in the combustion chamber 242 during the exhaust stroke is different from the airflow in the combustion chamber 242 during the compression stroke, and does not suppress the adhesion of the injected fuel N to the inner wall. As a result, when the fuel N is injected from the injection unit 43 into the combustion chamber 242 during the exhaust stroke, the fuel N may adhere to the inner wall of the combustion chamber 242. In this case, the fuel N adhering to the inner wall may mix with the lubricating oil that lubricates the piston 241, causing the engine 1 to break down. On the other hand, the injection control unit 624 according to this embodiment injects the fuel N into the combustion chamber 242 during the compression stroke from the injection unit 43 in the same manner as during normal combustion. In this way, the fuel N injected into the combustion chamber 242 of the first cylinder group 21 during compression release is diffused in the combustion chamber 242 and mixed with fresh air, as in normal operation. In other words, the fuel N is diffused by the air current that occurs in the combustion chamber 242 during the compression stroke, which prevents the fuel N from adhering to the inner wall, and therefore prevents the fuel N from adhering to the inner wall of the combustion chamber 242. As a result, the fuel N is prevented from mixing with the lubricating oil that lubricates the piston 241, which prevents the engine 1 from breaking down.

At this time, the pressure in the combustion chamber 242 of the first cylinder group 21 is reduced by releasing the compression of the first cylinder group 21, so the temperature of the air compressed in the combustion chamber 242 is below the temperature at which the mixture can burn. Therefore, when fuel N is injected into the combustion chamber 242 of the first cylinder group 21 during compression release, the mixture of fresh air and fuel N does not burn. Then, the mixture is discharged from the combustion chamber 242 to the first pipe 31 in an unburned state during the exhaust stroke of the first cylinder group 21. In other words, the injection control unit 624 can supply unburned fuel N to the exhaust pipe 3.

The mixture of unburned fuel N and air supplied to the first pipe 31 merges with the exhaust gas from the second cylinder group 22 in the third pipe 33, and is decomposed by the heat of the exhaust gas from the second cylinder group 22 into hydrocarbons. The hydrocarbons are supplied to the purification device 34, which is an oxidation catalyst. The supply of the hydrocarbons to the purification device 34 promotes the oxidation reaction in the purification device 34, and the hydrocarbons are burned. The combustion of the hydrocarbons increases the temperature of the exhaust gas flowing into the filter 35. Specifically, the temperature of the exhaust gas reaches a temperature (e.g., 500 degrees Celsius) at which the substance (soot) captured by the filter 35 can be incinerated. When the exhaust gas reaches the filter 35 at a temperature at which the substance captured by the filter 35 can be incinerated, the substance (soot, etc.) captured by the filter 35 is incinerated.

However, when unburned fuel is returned to the intake pipe 12, the amount of fuel that reaches the filter 35 is reduced, and the combustion temperature may not be sufficient to burn the material captured by the filter 35. In addition, when unburned fuel is returned to the intake pipe 12, there is a risk that excess fuel will be supplied to the combustion chamber 242 of the second cylinder group 22.

Therefore, when fuel is injected into the combustion chamber 242 of the first cylinder group 21 during compression release, the flow path control unit 625 does not supply the mixture of unburned fuel and air discharged from the first cylinder group 21 to the first return pipe 131. Figure 4 is a diagram for explaining the flow of exhaust gas discharged from cylinder 2. The white arrows in Figure 4 indicate the flow of the mixture of unburned fuel and air discharged from the first cylinder group 21. The black arrows in Figure 4 indicate the flow of exhaust gas discharged from the second cylinder group 22. A symbol with a cross in a circle indicates that gas does not flow in the pipe.

The flow path control unit 625 closes the first control valve 151 to prevent the unburned fuel and air mixture from being supplied to the first return line 131, and does not return the unburned fuel and air mixture to the intake line 12. As shown in FIG. 4, the mixture indicated by the white arrow does not flow to the first return line 131 at the branch point of the first line 31 and the first return line 131, but instead flows to the three-way valve 153. This allows the flow path control unit 625 to supply all of the unburned fuel and air mixture to the third line 33, and prevents excessive fuel from being supplied to the combustion chamber 242 of the second cylinder group 22.

If unburned fuel is supplied to the turbine 162, the fuel may adhere to the blades or motor of the turbine 162, causing the turbine 162 to break down. Therefore, the flow path control unit 625 does not allow unburned fuel to be supplied to the turbine 162. Specifically, when fuel is injected into the combustion chamber 242 of the first cylinder group 21 during compression release, the flow path control unit 625 allows the mixture of unburned fuel and air discharged from the first cylinder group 21 to be supplied to the bypass pipe 36. More specifically, the flow path control unit 625 controls the three-way valve 153 to connect the first pipe 31 to the bypass pipe 36 and to cut off the connection between the first pipe 31 and the turbine 162, thereby allowing the mixture of unburned fuel and air discharged from the first cylinder group 21 to be supplied to the bypass pipe 36.

As shown in FIG. 4, the air-fuel mixture indicated by the solid white arrows does not flow toward the turbine 162, but instead passes through the three-way valve 153 and flows toward the bypass line 36. In this way, the mixture of unburned fuel and air passes through the bypass line 36, which bypasses the turbine 162, and reaches the filter 35. In other words, the flow path control unit 625 can suppress the supply of the air-fuel mixture to the turbine 162.

The flow path control unit 625 does not recirculate the mixture of unburned fuel and air to the engine 1, but recirculates the exhaust gas of the second cylinder group 22 to the engine 1. Specifically, the flow path control unit 625 supplies a portion of the exhaust gas of the second cylinder group 22 to the second recirculation pipe 132 to recirculate it to the intake pipe 12. More specifically, the flow path control unit 625 opens the second control valve 152 to supply the exhaust gas of the second cylinder group 22 to the second recirculation pipe 132, thereby recirculating the exhaust gas of the second cylinder group 22 to the engine 1.

As shown in FIG. 4, the exhaust gas discharged from the second cylinder group 22 flows toward the second pipe 32 and the second recirculation pipe 132 at the branch point where the second pipe 32 branches into the second recirculation pipe 132. The exhaust gas flowing through the second pipe 32 passes through the turbine 162 and reaches the third pipe 33. The exhaust gas flowing through the second recirculation pipe 132 passes through the exhaust cooler 142 and the second control valve 152 and reaches the intake pipe 12. This allows the flow path control unit 625 to reduce the oxygen concentration of the intake air (mixture of fresh air and exhaust gas) supplied to the second cylinder group 22, thereby reducing the amount of nitrogen oxides generated during combustion in the combustion chamber 242 of the second cylinder group 22.

When the first cylinder bank 21 is compressed and released, a load is placed on the engine 1. In other words, the expansion stroke is performed with the air pressure in the combustion chamber reduced, which generates negative work on the engine 1, and so a load is placed on the engine 1. In order to achieve the desired output of the engine 1 when the first cylinder bank 21 is compressed and released, it is necessary to increase the amount of fuel injected into the second cylinder bank 22.

Therefore, when the first cylinder group 21 is compression-released, the injection control unit 624 injects a fourth injection amount of fuel, which is greater than the third injection amount, into the combustion chamber 242 of the second cylinder group 22. The third injection amount is the amount of fuel injected into the combustion chamber 242 of the second cylinder group 22 when the first cylinder group 21 is normally operated. Specifically, the injection control unit 624 determines the fourth injection amount according to the load generated in the engine 1 when the first cylinder group 21 is compression-released. More specifically, the injection control unit 624 determines the fourth injection amount by adding the amount of fuel according to the load generated in the engine 1 when the first cylinder group 21 is compression-released to the third injection amount. The injection control unit 624 controls the injection unit 43 to inject the determined fourth injection amount of fuel into the combustion chamber 242 of the second cylinder group 22.

In this way, the injection control unit 624 increases the amount of fuel injected into the second cylinder group 22 of the engine 1 that is under load due to the compression release of the first cylinder group 21. This allows the injection control unit 624 to increase the amount of fuel injected into the combustion chamber 242 of the second cylinder group 22 without increasing the actual output of the engine 1. As a result, the combustion temperature of the mixture increases, which in turn increases the temperature of the exhaust gas, making it easier for the unburned fuel discharged from the first cylinder group 21 to burn in the exhaust pipe 3.

The engine control device 6 may execute regeneration control of the filter 35 when the state of the engine 1 satisfies a predetermined condition. For example, when the rotation speed of the engine 1 is equal to or lower than a predetermined rotation speed, the number of combustions per unit time is smaller than when the rotation speed is higher than the predetermined rotation speed, so the temperature of the exhaust gas is less likely to rise and the material captured by the filter 35 is less likely to burn. Therefore, the engine control device 6 executes regeneration control of the filter 35 when regeneration control of the filter 35 is necessary and the rotation speed of the engine 1 is equal to or lower than a predetermined rotation speed. Specifically, when regeneration control of the filter 35 is necessary and the rotation speed of the engine 1 is equal to or lower than a predetermined rotation speed, the exhaust valve control unit 623 compresses and releases the first cylinder group 21, and the injection control unit 624 injects the second injection amount of fuel into the first cylinder group 21 during compression and release.

The specified rotation speed may be determined as appropriate based on the specifications of the engine 1 and on experiments. A specific value for the specified rotation speed is, for example, 2000 revolutions per minute in the case of a diesel engine, but is not limited to this. Unburned fuel is supplied to the exhaust pipe 3 by injecting fuel into the first cylinder group 21 during compression release. In this way, the engine control device 6 is able to appropriately execute regeneration control of the filter 35 by supplying unburned fuel to the exhaust pipe 3 in a situation where the exhaust temperature is unlikely to rise.

When the engine 1 speed is greater than the predetermined speed, the number of combustions per unit time is greater than when the speed is equal to or less than the predetermined speed, so the exhaust temperature is more likely to rise and the material captured by the filter 35 is more likely to burn. Therefore, even if regeneration control of the filter 35 is necessary, the engine control device 6 does not execute regeneration control of the filter 35 when the engine 1 speed is greater than the predetermined speed. The engine control device 6 may execute regeneration control of the filter 35 when regeneration control of the filter 35 is necessary and the state in which the engine 1 speed is greater than the predetermined speed continues for a predetermined time.

If regeneration control is performed when the engine 1 is under a large load, an excessive load is applied to the engine 1. Therefore, the engine control device 6 executes regeneration control of the filter 35 when regeneration control of the filter 35 is necessary, the engine 1 rotation speed is equal to or lower than a predetermined rotation speed, and the command injection amount is equal to or lower than a judgment threshold. Specifically, when regeneration control of the filter 35 is necessary, the engine 1 rotation speed is equal to or lower than a predetermined rotation speed, and the command injection amount is equal to or lower than a judgment threshold, the exhaust valve control unit 623 compresses and releases the first cylinder group 21, and the injection control unit 624 injects the second injection amount of fuel into the first cylinder group 21 during compression and release. The engine control device 6 does not execute regeneration control of the filter 35 when regeneration control of the filter 35 is necessary and the command injection amount is greater than the judgment threshold, even if the engine 1 rotation speed is equal to or lower than a predetermined rotation speed.

The judgment threshold is smaller than the maximum injection amount that can be injected into the combustion chamber 242 of the engine 1. Specifically, the judgment threshold is smaller than the maximum injection amount by a predetermined value. The predetermined value is determined, for example, based on the specifications of the engine 1 or on experiments. The specific value of the judgment threshold N is one-fifth (equivalent to 20 percent) of the maximum injection amount M, but is not limited to this. In this way, the engine control device 6 can suppress the execution of regeneration control when the engine 1 is under a large load, thereby suppressing excessive load on the engine 1.

[Process for Regenerating Filter 35]
5 is a flowchart showing an example of the flow of the process of regenerating the filter 35. The process of regenerating the filter 35 is executed at a predetermined interval while the engine 1 is operating. In other words, the process of regenerating the filter 35 is automatically executed while the vehicle equipped with the engine 1 is running. The predetermined interval may be set appropriately, for example, one minute, but is not limited to this. In addition, it is assumed that the acquisition unit 621 acquires the exhaust pressures upstream and downstream of the filter 35, the command injection amount of the engine 1, and the rotation speed of the engine 1.

The determination unit 622 determines whether or not regeneration control of the filter 35 is necessary (step S1). Specifically, the exhaust valve control unit 623 determines that regeneration control is unnecessary when the pressure difference between the exhaust pressure upstream of the filter 35 and the exhaust pressure downstream of the filter 35 is less than the determination threshold. When regeneration control is unnecessary (No in step S1), the determination unit 622 ends the process of regenerating the filter 35.

If the pressure difference is equal to or greater than a predetermined pressure, the determination unit 622 determines that regeneration control is necessary. If regeneration control is necessary (Yes in step S1), the determination unit 622 determines whether the rotation speed of the engine 1 is equal to or less than a predetermined rotation speed (step S2). If the rotation speed of the engine 1 is greater than the predetermined rotation speed (No in step S2), the determination unit 622 ends the process of regenerating the filter 35 because the number of combustions per unit time is high and the exhaust temperature is likely to be high.

If the rotation speed of the engine 1 is equal to or lower than a predetermined rotation speed (Yes in step S2), the determination unit 622 determines whether the commanded injection amount is equal to or lower than the determination threshold (step S3). If the commanded injection amount is greater than the determination threshold (No in step S3), the amount of fuel injected is large and a large load is applied to the engine 1, so the determination unit 622 ends the process of regenerating the filter 35.

If the commanded injection amount is equal to or less than the judgment threshold (Yes in step S3), the exhaust valve control unit 623 compresses and releases the first cylinder group 21 (step S4). Specifically, the exhaust valve control unit 623 opens the exhaust valve 42 of the first cylinder group 21 during the compression stroke of the first cylinder group 21. The injection control unit 624 controls the injector 43 to inject the second injection amount of fuel into the combustion chamber 242 of the first cylinder group 21 during compression release (step S5). The engine control device 6 repeatedly executes the processes of steps S1 to S5 until it is determined that regeneration control of the filter 35 is not necessary.

[Effects of the Reproduction System S]
As described above, when removing substances trapped in the filter 35, the regeneration system S opens the exhaust valves 42 of the first cylinder group 21, which are some of the cylinders, during the compression stroke of the first cylinder group 21, and while the exhaust valves 42 of the first cylinder group 21 are open, injects a second injection amount of fuel into the combustion chamber 242 of the first cylinder group 21. The second injection amount is less than the first injection amount injected into the combustion chamber 242 while the exhaust valve 42 is closed during the compression stroke.

In this way, the exhaust valve 42 opens during the compression stroke, so the pressure in the combustion chamber 242 drops and the temperature of the compressed air drops. In other words, the regeneration system S can inject fuel into the combustion chamber 242 when the temperature of the compressed air is lower than the combustion temperature of the air-fuel mixture. The fuel injected into the combustion chamber 242 is not burned in the combustion chamber 242 and is discharged in an unburned state and supplied to the exhaust pipe 3.

As described above, the regeneration system S can supply unburned fuel to the exhaust pipe 3 with a simple configuration in which the exhaust valve 42 is opened during the compression stroke of the first cylinder group 21 and fuel is injected into the first cylinder group 21 with the exhaust valve 42 open, without adding an injection device that injects fuel into the exhaust pipe 3 or piping and a pump that supplies fuel to the injection device. The unburned fuel supplied to the exhaust pipe 3 is then burned in the exhaust pipe 3 before reaching the filter 35. The combustion of the fuel in the exhaust pipe 3 raises the temperature of the exhaust gas to a temperature at which the material trapped in the filter 35 burns. As a result, the material (soot, etc.) trapped in the filter 35 is incinerated and removed.

Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the invention. For example, all or part of the device can be configured by distributing or integrating functionally or physically in any unit. In addition, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment resulting from the combination also has the effect of the original embodiment.

S Regeneration system 1 Engine 11 Sensor group 12 Intake pipe 16 Turbocharger 131 First return pipe 132 Second return pipe 141 Exhaust cooler 142 Exhaust cooler 143 Intercooler 151 First control valve 152 Second control valve 153 Three-way valve 161 Compressor 162 Turbine 2 Cylinder 21 First cylinder group 22 Second cylinder group 211 First cylinder 212 Second cylinder 213 Third cylinder 214 Fourth cylinder 241 Piston 242 Combustion chamber 3 Exhaust pipe 31
32 Second pipeline 33 Third pipeline 34 Purifier 35 Filter 36 Bypass pipeline 41 Intake valve 42 Exhaust valve 43 Injector 6 Engine control device 61 Memory unit 62 Control unit 621 Acquisition unit 622 Determination unit 623 Exhaust valve control unit 624 Injection control unit 625 Flow path control unit

Claims (6)

a filter provided in an exhaust pipe that discharges engine exhaust to the outside and that collects substances contained in the exhaust;
an exhaust valve control unit that controls opening and closing of exhaust valves of some of the cylinders among a plurality of cylinders of the engine during a compression stroke of the some of the cylinders;
an injection control unit that controls an injection unit that injects fuel into the combustion chamber of the part of the cylinders;
a turbine provided in the exhaust pipe of a turbocharger that compresses fresh air supplied to the engine;
a bypass pipe capable of supplying exhaust gas from the part of the cylinders to a portion of the exhaust pipe downstream of the turbine from between the engine and the turbine in the exhaust pipe;
a flow passage control unit that supplies exhaust gas from the part of the cylinders to the bypass pipe;
having
the exhaust pipe includes a first pipe that supplies exhaust gas from the partial cylinders to the turbine, and a second pipe that supplies exhaust gas from other cylinders different from the partial cylinders to the turbine,
the bypass pipe supplies exhaust gas from the part of the cylinders from between the engine and the turbine in the first pipe to a location downstream of the turbine in the exhaust pipe,
the exhaust valve control unit opens an exhaust valve during a compression stroke of the part of the cylinders when removing the substance trapped in the filter,
The injection control unit injects a second injection amount of fuel into the combustion chamber of the partial cylinder when the exhaust valve is open during the compression stroke, the second injection amount being smaller than a first injection amount of fuel to be injected into the combustion chamber of the partial cylinder when the exhaust valve is closed during the compression stroke of the partial cylinder.
When fuel is injected into the combustion chamber of the part of the cylinders with the exhaust valves open during the compression stroke, the flow path control unit supplies the exhaust gas from the part of the cylinders to the bypass pipe.
Playback system. The injection control unit injects the second injection amount of fuel into the combustion chamber of the part of the cylinders in a state where the exhaust valve is open during the compression stroke at the same timing as the timing of injecting fuel into the combustion chamber of the part of the cylinders in a state where the exhaust valve is closed during the compression stroke.
The playback system of claim 1 . a first return pipe that returns exhaust gas from the part of the cylinders to an intake pipe of the engine;
a second return pipe that returns exhaust gas from the other cylinder to the intake pipe,
When fuel is injected into the combustion chamber of the part of the cylinders with the exhaust valves open during the compression stroke, the flow path control unit supplies a part of the exhaust gas from the other cylinders to the second return pipe to return the part of the exhaust gas to the intake pipe, and does not supply the exhaust gas from the part of the cylinders to the first return pipe.
The playback system of claim 1 . When injecting fuel into the combustion chambers of the partial cylinders with the exhaust valves open during the compression stroke, the injection control unit injects a fourth injection amount of fuel into the combustion chambers of the partial cylinders with the exhaust valves of the partial cylinders closed during the compression stroke of the partial cylinders, the fourth injection amount being greater than a third injection amount of fuel to be injected into the combustion chambers of the partial cylinders different from the partial cylinders.
The playback system of claim 1 . When the exhaust valve opens during the compression stroke of the partial cylinder, the injection control unit injects the fourth injection amount of fuel, which is greater than the third injection amount by an amount corresponding to a load generated in the engine in a state in which the exhaust valve is open during the compression stroke of the partial cylinder, into the combustion chamber of the other cylinder.
The playback system according to claim 4 . the exhaust valve control unit opens the exhaust valve during the compression stroke of the part of the cylinders when removal of the material trapped in the filter is necessary, the engine speed is equal to or lower than a predetermined speed, and an instructed injection amount of fuel to be injected into the combustion chamber is equal to or lower than a predetermined value.
The playback system of claim 1 .

Images