Intake and exhaust system

Abstract

To rapidly increase the collection efficiency of a filter.SOLUTION: An intake and exhaust system includes an engine having a crank chamber, an intake flow passage connected to the engine, an exhaust flow passage connected to the engine, a filter provided in the exhaust flow passage, a blow-by flow passage connecting the crank chamber and the intake flow passage, and a control unit. The control unit has one or more processors, and one or more memories connected to the processors. The processors perform processing including controlling of a blow-by flow rate, which is the flow rate of blow-by gas flowing through the blow-by flow passage, on the basis of the pressure difference between a pressure upstream of the filter and a pressure downstream of the filter in the exhaust flow passage.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an intake and exhaust system. [Background technology]

[0002] Engines are required to keep emissions of particulate matter such as soot below a predetermined level. Therefore, as disclosed in Patent Document 1, a filter is provided in the exhaust flow path connected to the engine. The filter captures particulate matter such as soot in the exhaust gas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-023893 Summary of the Invention [Problem to be solved by the invention]

[0004] The collection efficiency of a filter increases as foreign matter clogs the pores of the filter. Therefore, the collection efficiency of a filter is low when it is new and increases as the filter is used. Here, in order to further reduce particulate matter emissions, it is considered desirable to quickly increase the collection efficiency of the filter, for example, after replacing the filter with a new one.

[0005] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an intake and exhaust system that can quickly increase the collection efficiency of the filter. [Means for solving the problem]

[0006] In order to solve the above problem, an intake and exhaust system according to one embodiment of the present invention comprises: an engine having a crankcase; an intake passage connected to the engine; an exhaust passage connected to the engine; a filter provided in the exhaust flow path; a blow-by passage connecting the crank chamber and the intake passage; a control device; Equipped with The control device one or more processors; one or more memories coupled to said processor; and The processor detects a pressure difference between a pressure upstream of the filter and a pressure downstream of the filter in the exhaust flow path. When the differential pressure is smaller than the reference differential pressure, compared with when the differential pressure is larger than the reference differential pressure, The blow-by flow rate, which is the flow rate of blow-by gas flowing through the blow-by flow passage, is Implement blow-by volume increase control to increase The process includes: [Effects of the Invention]

[0007] According to the present invention, it is possible to quickly increase the collection efficiency of the filter. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing the general configuration of an intake and exhaust system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing an example of a functional configuration of the control device according to the embodiment of the present invention. [Figure 3] 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 invention. [Figure 4] FIG. 4 is a diagram showing an example of the transition of collection efficiency after filter replacement in an intake / exhaust system according to a comparative example. [Figure 5] FIG. 5 is a diagram showing an example of the transition of collection efficiency after filter replacement in the intake and exhaust system according to the embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram showing a schematic configuration of an intake and exhaust system according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for facilitating understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0010] <Configuration of the intake and exhaust system> The configuration of an intake and exhaust system 1 according to an embodiment of the present invention will be described with reference to FIGS.

[0011] 1 is a schematic diagram showing the general configuration of an intake and exhaust system 1. The intake and exhaust system 1 is mounted on a vehicle 100. As shown in FIG. 1, the intake and exhaust system 1 includes an engine 10, an intake passage 20, an exhaust passage 30, a blow-by passage 40, and a control device 50.

[0012] The engine 10 is a horizontally opposed engine in which multiple cylinders 11 are arranged opposite each other. However, the engine 10 may be an engine other than a horizontally opposed engine. A piston 12 is slidably provided within the cylinder 11. A combustion chamber 13 is defined by the inner circumferential surface of the cylinder 11 and the crown surface of the piston 12. One end of a connecting rod 14 is connected to the piston 12. The other end of the connecting rod 14 is connected to a crankshaft 15. The crankshaft 15 is rotatably supported by a bearing (not shown) within a crank chamber 16.

[0013] Each cylinder 11 is formed with an intake port 17 and an exhaust port 18. The intake port 17 and the exhaust port 18 are in communication with the combustion chamber 13. The combustion chamber 13 is in communication with an intake passage 20 via the intake port 17, and is in communication with an exhaust passage 30 via the exhaust port 18. The intake port 17 is opened and closed by an intake valve (not shown). The exhaust port 18 is opened and closed by an exhaust valve (not shown). By driving the intake valve and the exhaust valve, intake air is supplied to the combustion chamber 13 and exhaust gas is discharged from the combustion chamber 13.

[0014] The intake flow path 20 is connected to the engine 10. The intake flow path 20 is a flow path through which intake air, which is air supplied to the combustion chamber 13 of the engine 10, flows. An air cleaner 21 is provided in the intake flow path 20. The air cleaner 21 removes foreign matter contained in the air taken into the intake flow path 20. A throttle valve 22 is provided in the intake flow path 20 downstream of the air cleaner 21. The throttle valve 22 adjusts the flow rate of intake air sent to the engine 10 through the intake flow path 20. The flow rate of intake air sent to the engine 10 changes depending on the opening degree of the throttle valve 22.

[0015] An intake manifold 20a is provided in the intake flow path 20 downstream of the throttle valve 22. The intake manifold 20a branches toward each cylinder 11 of the engine 10 and is connected to the intake port 17 of each cylinder 11. The air taken into the intake flow path 20 passes through an air cleaner 21, then passes through the throttle valve 22 and is sent to the engine 10.

[0016] The exhaust flow path 30 is connected to the engine 10. The exhaust flow path 30 is a flow path through which exhaust gas discharged from the combustion chamber 13 of the engine 10 flows. An exhaust manifold 30a is provided on the upstream side of the exhaust flow path 30. The exhaust manifold 30a branches out toward each cylinder 11 of the engine 10 and is connected to the exhaust port 18 of each cylinder 11.

[0017] A filter 31 is provided in the exhaust flow path 30 downstream of the exhaust manifold 30a. The filter 31 collects particulate matter such as soot in the exhaust gas. The filter 31 is also called, for example, a particulate filter. A muffler 32 is provided in the exhaust flow path 30 downstream of the filter 31. The muffler 32 reduces the noise generated when the exhaust gas is discharged. In the exhaust flow path 30, the exhaust gas discharged from the engine 10 passes through the filter 31 and the muffler 32 in this order before being discharged.

[0018] The exhaust flow path 30 is provided with a differential pressure sensor 33, a temperature sensor 34, an oxygen sensor 35, and an air-fuel ratio sensor 36. The differential pressure sensor 33 detects the differential pressure between the pressure upstream of the filter 31 in the exhaust flow path 30 and the pressure downstream of the filter 31. Specifically, the differential pressure detected by the differential pressure sensor 33 is the differential pressure between the exhaust gas pressure upstream of the filter 31 in the exhaust flow path 30 and the exhaust gas pressure downstream of the filter 31 in the exhaust flow path 30. Hereinafter, the differential pressure detected by the differential pressure sensor 33 will also be simply referred to as the differential pressure of the filter 31. The temperature sensor 34 detects the temperature of the exhaust gas flowing through the exhaust flow path 30. For example, the temperature sensor 34 detects the temperature of the exhaust gas upstream of the filter 31 in the exhaust flow path 30. The oxygen sensor 35 detects the oxygen concentration in the exhaust flow path 30. For example, the oxygen sensor 35 detects the oxygen concentration upstream of the filter 31 in the exhaust flow path 30. The air-fuel ratio sensor 36 detects the air-fuel ratio of the exhaust gas flowing through the exhaust flow path 30 .

[0019] The blow-by passage 40 connects the crank chamber 16 of the engine 10 with the intake passage 20. Here, unburned gas or burned gas may leak into the crank chamber 16 from the gap between the piston 12 and the cylinder 11. The gas that leaks into the crank chamber 16 is called blow-by gas. In the intake and exhaust system 1, the blow-by gas that leaks into the crank chamber 16 flows back from the crank chamber 16 to the intake passage 20 via the blow-by passage 40. The blow-by passage 40 is connected to the intake passage 20 on the downstream side of the throttle valve 22. Hereinafter, the crank chamber 16 side of the blow-by passage 40 will be referred to as the upstream side, and the intake passage 20 side will be referred to as the downstream side.

[0020] The blow-by passage 40 is provided with a flow rate adjustment valve 41 and a check valve 42, arranged in this order from the upstream side. A change in the opening degree of the flow rate adjustment valve 41 changes the blow-by flow rate, which is the flow rate of blow-by gas flowing through the blow-by passage 40. The check valve 42 allows gas to flow from the blow-by passage 40 toward the intake passage 20 and restricts gas to flow from the intake passage 20 toward the blow-by passage 40. As a result, when the pressure in the blow-by passage 40 is higher than the pressure in the intake passage 20, the blow-by gas flows back from the crank chamber 16 to the intake passage 20 via the blow-by passage 40. On the other hand, when the pressure in the intake passage 20 is higher than the pressure in the blow-by passage 40, the backflow of intake air from the intake passage 20 to the blow-by passage 40 is prevented.

[0021] The control device 50 has one or more processors 50a and one or more memories 50b connected to the processors 50a. The processor 50a includes, for example, a CPU (Central Processing Unit). The memory 50b includes, for example, a ROM (Read Only Memory) and a RAM (Random Access Memory). The ROM is a storage element that stores programs and calculation parameters used by the CPU. The RAM is a storage element that temporarily stores data such as variables and parameters used in processing executed by the CPU.

[0022] The control device 50 communicates with each device provided in the intake and exhaust system 1. For example, the control device 50 communicates with a differential pressure sensor 33, a temperature sensor 34, an oxygen sensor 35, an air-fuel ratio sensor 36, and a flow rate control valve 41. The communication between the control device 50 and each device is realized, for example, using CAN (Controller Area Network) communication.

[0023] Fig. 2 is a block diagram showing an example of the functional configuration of the control device 50. For example, as shown in Fig. 2, the control device 50 has an acquisition unit 51 and a control unit 52. Note that various processes, including the processes described below, performed by the acquisition unit 51 or the control unit 52 may be executed by the processor 50a. In detail, the various processes are executed by the processor 50a executing a program stored in the memory 50b.

[0024] The acquisition unit 51 acquires various information used in the processing performed by the control unit 52 and outputs the information to the control unit 52. For example, the acquisition unit 51 acquires information from the differential pressure sensor 33, the temperature sensor 34, the oxygen sensor 35, and the air-fuel ratio sensor 36.

[0025] The control unit 52 controls the operation of each device in the intake and exhaust system 1. In particular, the control unit 52 controls the opening degree of the flow rate adjustment valve 41 to control the blow-by flow rate, which is the flow rate of blow-by gas flowing through the blow-by flow path 40.

[0026] The functions of the control device 50 according to this embodiment may be divided among multiple devices, or multiple functions may be realized by one device. When the functions of the control device 50 are divided among multiple devices, the multiple devices may be connected to each other via a communication bus such as a CAN.

[0027] <Intake and exhaust system operation> Next, the operation of the intake and exhaust system 1 according to the embodiment of the present invention will be described with reference to FIGS.

[0028] In this embodiment, the control unit 52 controls the blow-by flow rate based on the differential pressure between the pressure upstream of the filter 31 and the pressure downstream of the filter 31 in the exhaust flow path 30 (i.e., the differential pressure of the filter 31). As a result, as will be described later, the collection efficiency of the filter 31 can be quickly increased. Hereinafter, with reference to FIG. 3, an example will be described in which, when the differential pressure of the filter 31 is smaller than a reference differential pressure, blow-by amount increase control is executed to increase the blow-by flow rate compared to when the differential pressure of the filter 31 is larger than the reference differential pressure. However, as will be described later, the processing performed by the control unit 52 is not limited to the example shown in FIG. 3.

[0029] Fig. 3 is a flowchart showing an example of the flow of processing performed by the control device 50. The control flow shown in Fig. 3 is started, for example, when the filter 31 is replaced with a new filter 31.

[0030] When the control flow shown in FIG. 3 starts, first, in step S101, the acquisition unit 51 acquires the differential pressure of the filter 31 from the differential pressure sensor 33.

[0031] Next, in step S102, the control unit 52 determines whether the differential pressure of the filter 31 is smaller than the reference differential pressure. Here, the larger the differential pressure of the filter 31, the higher the collection efficiency of the filter 31. For example, since the pores of a new filter 31 are not clogged with foreign matter, the collection efficiency of the filter 31 is low. In this case, the differential pressure of the filter 31 is small. Then, as the filter 31 is used, foreign matter clogs the pores of the filter 31, and the collection efficiency of the filter 31 increases. Accordingly, the differential pressure of the filter 31 also increases.

[0032] The reference differential pressure in step S102 is the differential pressure when the collection efficiency of the filter 31 is the target efficiency. Therefore, if the differential pressure of the filter 31 is smaller than the reference differential pressure, it can be determined that the collection efficiency of the filter 31 is lower than the target efficiency. On the other hand, if the differential pressure of the filter 31 is larger than the reference differential pressure, it can be determined that the collection efficiency of the filter 31 is higher than the target efficiency. The reference differential pressure is set to a value that makes it possible to determine whether the collection efficiency of the filter 31 is higher than the target efficiency, and is set appropriately depending on the specifications of the filter 31, etc.

[0033] If it is determined that the differential pressure of the filter 31 is greater than the reference differential pressure (NO in step S102), the process proceeds to step S103. Note that if the differential pressure of the filter 31 matches the reference differential pressure, the process may proceed to step S103 or step S104. In step S103, the control unit 52 executes normal control, and the control flow shown in FIG. 3 ends.

[0034] The normal control is a control for setting the blow-by flow rate to a predetermined flow rate that is smaller than the blow-by flow rate in the blow-by amount increase control. For example, in the normal control, the control unit 52 controls the opening degree of the flow rate adjustment valve 41 to a predetermined opening degree that is smaller than the opening degree in the blow-by amount increase control.

[0035] If it is determined that the differential pressure of the filter 31 is smaller than the reference differential pressure (YES in step S102), the process proceeds to step S104. In step S104, the control unit 52 determines whether or not the prohibition condition for the blow-by amount increase control is satisfied.

[0036] As will be described later, the blow-by amount increase control makes it possible to quickly increase the collection efficiency of the filter 31. However, there are situations in which it is preferable to prohibit the blow-by amount increase control. The prohibition condition is a condition for prohibiting the blow-by amount increase control in such situations.

[0037] For example, the prohibition condition may be that the temperature of the exhaust gas flowing through the exhaust passage 30 is lower than a reference temperature. In the blow-by increase control, the amount of engine oil that is recirculated to the intake passage 20 and supplied to the combustion chamber 13 of the engine 10 is increased. A portion of the engine oil supplied to the combustion chamber 13 may be combusted in the exhaust passage 30. Therefore, if the temperature of the exhaust gas flowing through the exhaust passage 30 is excessively low, the engine oil may not be sufficiently combusted in the exhaust passage 30, and unburned engine oil may be discharged. Therefore, in order to suppress the discharge of unburned engine oil, it is preferable to prohibit the blow-by increase control when the temperature of the exhaust gas flowing through the exhaust passage 30 is lower than a reference temperature. The temperature of the exhaust gas flowing through the exhaust passage 30 may be obtained, for example, from the temperature sensor 34.

[0038] Furthermore, for example, the prohibition condition may be that the oxygen concentration in the exhaust passage 30 is lower than a reference concentration. As described above, a portion of the engine oil supplied to the combustion chamber 13 may be combusted in the exhaust passage 30. Therefore, if the oxygen concentration in the exhaust passage 30 is excessively low, the engine oil may not be sufficiently combusted in the exhaust passage 30, and unburned engine oil may be discharged. Therefore, in order to suppress the discharge of unburned engine oil, it is preferable to prohibit the blow-by increase control when the oxygen concentration in the exhaust passage 30 is lower than a reference concentration. The oxygen concentration in the exhaust passage 30 may be obtained, for example, from the oxygen sensor 35.

[0039] Furthermore, for example, the prohibition condition may be that the operating state of the engine 10 is in a specific state. A portion of the engine oil supplied to the combustion chamber 13 may be combusted within the combustion chamber 13. Therefore, when the operating state of the engine 10 is in a specific state in which combustion within the combustion chamber 13 is unlikely to occur, the engine oil may not be sufficiently combusted within the combustion chamber 13, and unburned engine oil may be discharged. An example of the specific state is when the air-fuel ratio is unstable. The air-fuel ratio may be obtained from, for example, the air-fuel ratio sensor 36. Therefore, in order to suppress the discharge of unburned engine oil, it is preferable to prohibit the blow-by increase control when the operating state of the engine 10 is in the specific state.

[0040] The prohibition condition for the blow-by amount increase control may be that any one or more of the above-mentioned conditions are satisfied, or may be that all of the above-mentioned conditions are satisfied. Also, the prohibition condition for the blow-by amount increase control is not limited to the example described above.

[0041] If it is determined that the prohibition condition for the blow-by amount increase control is satisfied (YES in step S104), the process proceeds to step S105. In step S105, the control unit 52 executes normal control, and the process returns to step S101.

[0042] If it is determined that the prohibition condition for the blow-by amount increase control is not satisfied (NO in step S104), the process proceeds to step S106. In step S106, the control unit 52 executes the blow-by amount increase control, and the process returns to step S101.

[0043] The blow-by amount increase control is a control for increasing the blow-by flow rate compared to the blow-by flow rate in normal control. For example, in the blow-by amount increase control, the control unit 52 increases the opening degree of the flow rate adjustment valve 41 compared to the opening degree in normal control.

[0044] 3, when the differential pressure across the filter 31 is smaller than the reference differential pressure, the control unit 52 executes blow-by amount increase control to increase the blow-by flow rate compared to when the differential pressure across the filter 31 is larger than the reference differential pressure. When the blow-by amount increase control is executed, the amount of engine oil that is recirculated to the intake passage 20 and supplied to the combustion chamber 13 of the engine 10 increases.

[0045] When components such as calcium, zinc, or sulfur contained in engine oil are burned, ash, which is particulate matter, is generated as unburned residue. Unlike soot, once ash is collected on the filter 31, it continues to accumulate on the filter 31. As a result, the pores of the filter 31 are clogged with ash, increasing the collection efficiency of the filter 31. When blow-by increase control is executed, the amount of ash generated per hour increases, and the rate at which the amount of ash accumulated on the filter 31 increases increases. As a result, the rate at which the collection efficiency of the filter 31 increases increases. This makes it possible to quickly increase the collection efficiency of the filter 31 in situations where the collection efficiency of the filter 31 is low, such as immediately after the filter 31 has been replaced.

[0046] As described above, the differential pressure of the filter 31 also increases as the collection efficiency of the filter 31 increases. Therefore, in the control flow of Fig. 3, when the blow-by amount increase control is executed and the collection efficiency of the filter 31 exceeds the target efficiency and the differential pressure of the filter 31 exceeds the reference differential pressure, the determination in step S102 is NO, and the blow-by amount increase control ends.

[0047] FIG. 4 is a diagram showing an example of the transition of collection efficiency after filter replacement in an intake / exhaust system according to a comparative example. In the comparative example, the blow-by increase control of this embodiment is not executed, and only normal control is executed. That is, in the comparative example, unlike this embodiment, control of the blow-by flow rate based on the differential pressure of the filter 31 is not executed. Therefore, after filter replacement, normal control is executed, and the amount of ash deposited on the filter 31 increases at an increasing rate corresponding to normal control. Therefore, the collection efficiency of the filter 31 also increases at an increasing rate corresponding to normal control. In the example of FIG. 4, after filter replacement, the collection efficiency of the filter 31 reaches the target efficiency at time T1.

[0048] FIG. 5 is a diagram showing an example of the transition of the collection efficiency after filter replacement in the intake / exhaust system 1 according to this embodiment. Note that in FIG. 5, the transition of the collection efficiency in the comparative example in FIG. 4 is indicated by a two-dot chain line. As described above, in this embodiment, when the differential pressure of the filter 31 is smaller than the reference differential pressure, the blow-by amount increase control is executed. Therefore, after filter replacement, when the collection efficiency of the filter 31 is lower than the target efficiency, the blow-by amount increase control is executed. As a result, after filter replacement, the amount of ash deposited on the filter 31 increases at a rate greater than the rate corresponding to normal control. Therefore, the collection efficiency of the filter 31 also increases at a rate greater than the rate corresponding to normal control. In the example of FIG. 5, after filter replacement, the collection efficiency of the filter 31 reaches the target efficiency at time T2, which is before time T1. As such, according to this embodiment, the collection efficiency of the filter 31 can be quickly increased after filter replacement, etc.

[0049] The configuration of the intake and exhaust system 1 has been described above with reference to Fig. 1. However, the configuration of the intake and exhaust system according to the present invention is not limited to the example in Fig. 1, and components may be appropriately deleted, changed, or added to the above-described intake and exhaust system 1. For example, the configuration of the intake and exhaust system according to the present invention may be the configuration shown in Fig. 6.

[0050] 6 is a schematic diagram showing the general configuration of an intake and exhaust system 1A according to a modified example. The intake and exhaust system 1A differs from the above-described intake and exhaust system 1 in that a blow-by passage 60 is provided in addition to the blow-by passage 40.

[0051] The blow-by passage 60 connects the crank chamber 16 of the engine 10 with the intake passage 20. In the intake and exhaust system 1A, in addition to the flow of blow-by gas that returns from the crank chamber 16 to the intake passage 20 via the blow-by passage 40, there is also a flow of blow-by gas that returns from the crank chamber 16 to the intake passage 20 via the blow-by passage 60. The blow-by passage 60 is connected to the intake passage 20 on the downstream side of the air cleaner 21 and the upstream side of the throttle valve 22.

[0052] A flow rate control valve 61 is provided in the blow-by flow path 60. A change in the opening degree of the flow rate control valve 61 changes the blow-by flow rate, which is the flow rate of blow-by gas flowing through the blow-by flow path 60. The opening degree of the flow rate control valve 61 is controlled by the control device 50. The control unit 52 of the control device 50 controls the opening degree of the flow rate control valve 61 in addition to the opening degree of the flow rate control valve 41. This makes it possible to control the blow-by flow rate, which is the flow rate of blow-by gas flowing through the blow-by flow path 40 and the blow-by flow path 60. For example, in the blow-by amount increase control, the control unit 52 increases the opening degrees of both the flow rate control valve 41 and the flow rate control valve 61 compared to the opening degrees in the normal control. This makes it possible to quickly increase the collection efficiency of the filter 31 after filter replacement, etc., as in the intake and exhaust system 1 described above.

[0053] In the above example, the blow-by amount increase control is executed to increase the blow-by flow rate when the differential pressure across the filter 31 is smaller than the reference differential pressure, compared to when the differential pressure across the filter 31 is larger than the reference differential pressure. However, the control unit 52 only needs to control the blow-by flow rate based on the differential pressure across the filter 31, and the processing performed by the control unit 52 is not limited to the example shown in FIG. 3. For example, in the above example, the blow-by flow rate is changed in two stages depending on the differential pressure across the filter 31, but the control unit 52 may change the blow-by flow rate in three or more stages depending on the differential pressure across the filter 31. Furthermore, for example, the control unit 52 may continuously change the blow-by flow rate depending on the differential pressure across the filter 31. In these cases, the control unit 52 increases the blow-by flow rate as the differential pressure across the filter 31 decreases.

[0054] <Effects of the intake and exhaust system> Next, the effects of the intake and exhaust system 1 according to the embodiment of the present invention will be described.

[0055] In the intake and exhaust system 1 according to this embodiment, the processor 50a executes processing that includes controlling the blow-by flow rate, which is the flow rate of blow-by gas flowing through the blow-by flow path 40, based on the pressure difference between the pressure upstream of the filter 31 and the pressure downstream of the filter 31 in the exhaust flow path 30. This makes it possible to change the rate at which the amount of ash deposited on the filter 31 increases, depending on the current collection efficiency of the filter 31. Therefore, it is possible to change the rate at which the collection efficiency of the filter 31 increases, depending on the current collection efficiency of the filter 31. Therefore, it is possible to quickly increase the collection efficiency of the filter 31.

[0056] Furthermore, in the intake / exhaust system 1 according to this embodiment, it is preferable that the processor 50a executes processing including executing blow-by amount increase control to increase the blow-by flow rate when the differential pressure across the filter 31 is smaller than the reference differential pressure, compared to when the differential pressure across the filter 31 is larger than the reference differential pressure. This makes it possible to increase the rate at which the amount of ash deposited on the filter 31 increases, for example, after filter replacement when the collection efficiency of the filter 31 is lower than the target efficiency. Therefore, it is possible to increase the rate at which the collection efficiency of the filter 31 increases, for example, after filter replacement. Therefore, it is possible to appropriately achieve a rapid increase in the collection efficiency of the filter 31, for example, after filter replacement.

[0057] Furthermore, in the intake and exhaust system 1 according to this embodiment, it is preferable that the processor 50a executes processing that includes prohibiting the blow-by increase control when the temperature of the exhaust gas flowing through the exhaust passage 30 is lower than a reference temperature. This makes it possible to prohibit the blow-by increase control when the temperature of the exhaust gas flowing through the exhaust passage 30 is low and it is difficult for engine oil to be burned in the exhaust passage 30. Therefore, it is possible to suppress the discharge of unburned engine oil based on the temperature of the exhaust gas flowing through the exhaust passage 30.

[0058] Furthermore, in the intake and exhaust system 1 according to this embodiment, it is preferable that the processor 50a executes processing including prohibiting the blow-by increase control when the oxygen concentration in the exhaust flow path 30 is lower than a reference concentration. This makes it possible to prohibit the blow-by increase control when the oxygen concentration in the exhaust flow path 30 is low and engine oil combustion in the exhaust flow path 30 is difficult. Therefore, it is possible to suppress the discharge of unburned engine oil based on the oxygen concentration in the exhaust flow path 30.

[0059] Furthermore, in the intake and exhaust system 1 according to this embodiment, it is preferable that the processor 50a executes processing including prohibiting the blow-by amount increase control when the operating state of the engine 10 is in a specific state. This makes it possible to prohibit the blow-by amount increase control when it is difficult to burn engine oil in the combustion chamber 13. Therefore, it is possible to suppress the discharge of unburned engine oil based on the operating state of the engine 10.

[0060] The above describes a preferred embodiment of the present invention with reference to the accompanying drawings. However, it goes without saying that the present invention is not limited to the above-described embodiment, and various modified or altered examples within the scope of the claims also fall within the technical scope of the present invention.

[0061] For example, the processes described herein using flowcharts do not necessarily have to be performed in the order shown in the flowcharts, and additional process steps may be employed or some process steps may be omitted. [Explanation of symbols]

[0062] 1. Intake and exhaust system 1A Intake and Exhaust System 10 Engine 11 cylinders 12 pistons 13 Combustion chamber 14 Connecting rod 15 crankshaft 16 Crankcase 17 Intake port 18 Exhaust port 20 intake passage 21 Air cleaner 22 Throttle valve 30 Exhaust flow path 31 filters 32 Muffler 33 Differential pressure sensor 34 Temperature Sensor 35 Oxygen sensor 36 Air-fuel ratio sensor 40 Blow-by passage 41 Flow control valve 42 Check valve 50 Control device 50a processor 50b memory 51 Acquisition Department 52 Control section 60 Blow-by passage 61 Flow control valve 100 vehicles

Claims

1. an engine having a crankcase; an intake passage connected to the engine; an exhaust passage connected to the engine; a filter provided in the exhaust flow path; a blow-by passage connecting the crank chamber and the intake passage; a control device; Equipped with The control device one or more processors; one or more memories coupled to the processor; and the processor executes processing including: when a differential pressure between a pressure upstream of the filter and a pressure downstream of the filter in the exhaust flow passage is smaller than a reference differential pressure, executing a blow-by amount increase control to increase a blow-by flow rate, which is a flow rate of blow-by gas flowing through the blow-by flow passage, compared to when the differential pressure is larger than the reference differential pressure. Intake and exhaust system.

2. the processor executes a process including prohibiting the blow-by amount increase control when the temperature of the exhaust gas flowing through the exhaust passage is lower than a reference temperature. The intake and exhaust system according to claim 1 .

3. the processor executes a process including prohibiting the blow-by amount increase control when the oxygen concentration in the exhaust passage is lower than a reference concentration. The intake and exhaust system according to claim 1 or 2.

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