JP2019052562A - Exhaust treatment device - Google Patents

Abstract

To suppress the sudden rise of a temperature during the regeneration of a PM (Particulate Matter) removal filter under operation condition of a low intake air amount, without increasing a fuel consumption and a manufacturing cost.SOLUTION: A control device performs control processing including a step of opening a bypass valve at a base opening (S104) when an operation region of an engine falls into a B' region (S102) during the regeneration of a PM removal filter (YES in S100), and when an intake air amount is smaller than a lower limit intake air amount (YES in S106), performs control processing including a step of calculating a pressure at a C point (S108), a step of calculating a pressure at a D point (S110), a step of calculating a pressure at an E point (S112), a step of calculating the flow rate of air flowing in a bypass passage using a C-E point differential pressure and a D-E point differential pressure (S114), and a step of adjusting the opening of the bypass valve so that the opening becomes a target opening (S116).SELECTED DRAWING: Figure 3

Description

  The present invention relates to an exhaust treatment device that purifies engine exhaust.

  In order to purify particulate matter (PM) in exhaust such as a diesel engine, an exhaust treatment device is provided in the exhaust pipe of the engine. The exhaust treatment device includes, for example, a PM removal filter that collects particulate matter, and an oxidation catalyst (DOC) disposed upstream of the PM removal filter in the exhaust flow. When the amount of particulate matter accumulated in the PM removal filter increases, the filter becomes clogged and the exhaust purification function decreases. Therefore, the particulate matter collected by burning the PM removal filter is burned to filter the filter. The so-called PM removal filter that is removed from is regenerated.

  In regeneration of the PM removal filter, fuel is added to the exhaust gas, the added fuel is reacted with an oxidation catalyst, and the exhaust heat is regenerated to a temperature range (about 600 ° C. to 700 ° C.) where the PM removal filter can be regenerated. Raise the temperature. Then, the exhaust gas that has reached a high temperature flows through the PM removal filter, whereby the PM in the PM removal filter burns.

  When the engine operating conditions change during the regeneration of such a PM removal filter and the flow rate of the exhaust gas decreases, the temperature of the PM removal filter may rapidly increase.

  Therefore, for example, Japanese Patent Application Laid-Open No. 2003-206726 (Patent Document 1) discloses a technique for suppressing a decrease in the flow rate of exhaust gas by heating the supercharged air with a heater and joining the air to the exhaust manifold.

JP 2003-206726 A

  However, in the above-mentioned Patent Document 1, a heater for heating air is separately provided in a pipe connecting the intake pipe through which the air after supercharging flows and the exhaust manifold, and the manufacturing cost increases. Occurs. It is also conceivable to change the engine operating conditions so as to suppress the decrease in the exhaust flow rate. As a result, when the engine speed increases, the fuel consumption increases and the fuel consumption deteriorates. The problem occurs.

  The present invention has been made to solve the above-described problems, and its object is to increase the temperature of the PM removal filter during regeneration of the PM removal filter without increasing the fuel consumption and the manufacturing cost. It is to provide an exhaust treatment device that suppresses.

  An exhaust treatment apparatus according to an aspect of the present invention is connected to an engine, an exhaust passage through which exhaust flows, a filter that is provided in the exhaust passage and collects particulate matter contained in the exhaust flowing through the exhaust passage, An intake passage that is connected to the engine and through which the intake air flows, a supercharger that supercharges the intake air that flows through the intake passage using the energy of the exhaust gas that flows through the exhaust passage, and a supercharger by the supercharger in the intake passage A bypass passage that connects a portion through which the intake air circulates, a portion of the exhaust passage between the supercharger and the filter, and an on-off valve capable of adjusting a flow rate of air flowing through the bypass passage; And a control device for adjusting the opening degree of the on-off valve. When the engine operating state shifts to a predetermined operating state with a low load and a low rotational speed during the regeneration for burning the particulate matter deposited on the filter, the control device detects the first pressure in the bypass passage. The differential pressure between the second pressure in the intake passage closer to the supercharger than the connection position between the intake passage and the bypass passage, and the third pressure and the second pressure in the intake passage closer to the engine than the connection position The flow rate of the air flowing through the bypass passage is estimated using the differential pressure, and the opening of the on-off valve is adjusted so that the flow rate of the gas flowing through the filter becomes a flow rate that suppresses overheating of the filter.

  In this way, when the operating state of the engine shifts to a predetermined operating state during regeneration of the filter, the on-off valve is opened to operate with the exhaust energy before shifting to the predetermined operating state. The air supercharged by the supercharger flows from the intake passage to the exhaust passage upstream of the filter via the bypass passage. As a result, the flow rate of the gas flowing through the filter can be increased. In particular, since the amount of air in the bypass passage can be accurately estimated using the first pressure, the second pressure, and the third pressure, the gas flow rate that flows through the filter is a flow rate that suppresses overheating of the filter. The opening degree of the on-off valve can be adjusted with high accuracy. Thereby, the rapid rise of the temperature of a filter can be suppressed. In addition, since the operating state of the engine is not changed so that the fuel consumption is deteriorated, and parts such as a heater are not separately provided, an increase in fuel consumption and manufacturing cost can be suppressed.

  Preferably, the control device adjusts the opening degree of the on-off valve after setting the opening degree of the on-off valve to a predetermined base opening degree when the operating state of the engine shifts to a predetermined operating state.

  In this way, since the opening of the opening / closing valve is opened until the predetermined base opening is reached, air can be quickly circulated in the bypass passage, so that a rapid increase in the temperature of the filter can be suppressed. it can.

  More preferably, the control device adjusts the opening degree of the on-off valve so that the sum of the flow rate of the gas flowing from the exhaust passage to the filter and the flow rate of the air flowing through the bypass passage becomes a flow rate that suppresses overheating of the filter. To do.

  In this way, when the engine operating state shifts to a predetermined operating state during regeneration of the filter, it is possible to increase the flow rate of the gas flowing through the filter and suppress a rapid increase in the temperature of the filter.

  More preferably, the exhaust treatment device further includes an exhaust pressure detection unit that detects a pressure in the exhaust passage closer to the supercharger than the filter. The control device estimates the first pressure based on the pressure detected by the exhaust pressure detection unit and the opening degree of the on-off valve.

  In this way, the first pressure can be estimated with high accuracy in consideration of the pressure loss based on the opening degree of the on-off valve.

  More preferably, the control device estimates the second pressure based on the engine speed and the amount of fuel supplied to the engine.

  In this way, the second pressure can be estimated with high accuracy from the engine speed and the amount of fuel supplied to the engine.

  More preferably, the exhaust processing device includes an intake pressure detection unit that detects a pressure in the intake passage closer to the engine than the connection position, and an intake throttle valve that is provided in the intake passage between the connection position and the intake pressure detection unit. And further comprising. The control device estimates the third pressure based on the pressure detected by the intake pressure detection unit and the opening of the intake throttle valve.

  In this way, the third pressure can be estimated with high accuracy in consideration of the pressure loss based on the opening of the intake throttle valve.

  More preferably, after the opening of the on-off valve, the control device, when a predetermined time elapses after the operating state of the engine shifts to a predetermined operating state during regeneration of the filter, the operating state of the engine The open / close valve is closed when at least one of the above is in an operation state different from the predetermined operation state and when the regeneration of the filter is completed.

  If it does in this way, since it can control that the open state of an on-off valve is continued unnecessarily, the fall of supercharging pressure can be controlled.

  According to the present invention, it is possible to provide an exhaust treatment device that suppresses a rapid rise in the temperature of the PM removal filter during regeneration of the PM removal filter without increasing fuel consumption and manufacturing cost.

It is a figure which shows schematic structure of the engine in this Embodiment. It is a figure which shows the relationship between an engine speed and load. It is a flowchart which shows the control processing performed with a control apparatus. It is a figure for demonstrating operation | movement of a control apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 is a diagram showing a schematic configuration of an engine 1 in the present embodiment. In the present embodiment, the engine 1 may be a diesel engine. Hereinafter, a common rail diesel engine will be described as an example.

  The engine 1 includes an engine block 2, an intake manifold 28, a supercharger 30, an exhaust manifold 50, an exhaust treatment device 56, and an exhaust gas recirculation device (hereinafter referred to as an EGR (Exhaust Gas Recirculation) device) 60. And a control device 200, an engine speed sensor 202, an atmospheric pressure sensor 204, and an air flow meter 208.

  The engine block 2 includes a plurality of cylinders 4, and each of the plurality of cylinders 4 is provided with a plurality of injectors (not shown). In the present embodiment, the engine 1 will be described by taking an in-line four-cylinder engine as an example, but it may be an engine of another cylinder layout (for example, a V type or a horizontal type).

  Each of the plurality of injectors is connected to a common rail. The fuel stored in the fuel tank is pressurized to a predetermined pressure by a fuel pump (both not shown) via a fuel filter and supplied to the common rail. The fuel supplied to the common rail is injected from each of the plurality of injectors at a predetermined timing. The plurality of injectors 16 operate based on a control signal from the control device 200.

  The air cleaner (not shown) removes foreign substances from the air sucked from the outside of the engine 1. One end of the first intake pipe 22 is connected to the air cleaner.

  The other end of the first intake pipe 22 is connected to the inlet of the compressor 32 of the supercharger 30. One end of the second intake pipe 24 is connected to the outlet of the compressor 32. The compressor 32 supercharges the air flowing from the first intake pipe 22 using the energy of the exhaust gas flowing through the first exhaust pipe 52 described later, and supplies the air to the second intake pipe 24.

  One end of a third intake pipe 27 is connected to the other end of the second intake pipe 24. Note that the third intake pipe 27 may be provided with, for example, an intercooler that is an air-cooled or water-cooled heat exchanger that cools the air flowing through the third intake pipe 27.

  An intake manifold 28 is connected to the other end of the third intake pipe 27. The intake manifold 28 is connected to each intake port of the plurality of cylinders 4 formed in the engine block 2. The intake throttle valve 10 is provided in the third intake pipe 27 upstream of the intake manifold 28. Further, the intake manifold 28 is provided with an intake pressure sensor 18.

  The exhaust manifold 50 is connected to each exhaust port of the plurality of cylinders 4 formed in the engine block 2. One end of a first exhaust pipe 52 is connected to the exhaust manifold 50. The other end of the first exhaust pipe 52 is connected to the inlet of the turbine 36 of the supercharger 30. Therefore, the exhaust discharged from the exhaust port of each cylinder is collected in the exhaust manifold 50 and then supplied to the turbine 36 via the first exhaust pipe 52.

  One end of the second exhaust pipe 54 is connected to the outlet of the turbine 36. The other end of the second exhaust pipe 54 is connected to an inlet portion of the exhaust treatment device 56. The exhaust treatment device 56 includes an oxidation catalyst (DOC: Diesel Oxidation Catalyst) 56a, a PM removal filter 56b, and a differential pressure sensor 56c.

  The PM removal filter 56b is provided downstream of the oxidation catalyst 56a in the exhaust passage (exhaust passage). The first detection element of the differential pressure sensor 56c is provided in the exhaust pipe between the oxidation catalyst 56a and the PM removal filter 56b. The second detection element of the differential pressure sensor 56 c is provided in the exhaust pipe between the PM removal filter 56 b and the third exhaust pipe 58. The differential pressure sensor 56c is a differential pressure (relative pressure) between the pressure in the exhaust pipe between the oxidation catalyst 56a and the PM removal filter 56b and the pressure in the exhaust pipe between the PM removal filter 56b and the third exhaust pipe 58. Is detected.

  The PM removal filter 56b collects particulate matter (hereinafter referred to as PM (Particulate Matter)) contained in the exhaust gas flowing through the exhaust treatment device 56. The PM removal filter 56b is formed of, for example, ceramic or stainless steel. The collected PM accumulates in the PM removal filter 56b.

  The oxidation catalyst 56a functions as a regeneration mechanism that burns and removes (regenerates) the PM deposited on the PM removal filter 56b. The oxidation catalyst 56a oxidizes nitrogen oxide (NOx), carbon oxide (COx), etc. in the flowing exhaust when the exhaust flows, and a fuel addition device in the exhaust upstream of the oxidation catalyst 56a. When the fuel added from is contained, the fuel is oxidized. You may use the injector provided in each cylinder as a fuel addition apparatus. By performing post injection in the combustion stroke of each cylinder, fuel is added to the exhaust from the injector. The temperature of the exhaust gas passing through the oxidation catalyst 56a rises due to the reaction heat generated by the oxidation of the fuel. When the high-temperature exhaust gas passes through the PM removal filter 56b, the temperature of the PM removal filter 56b rises, and the PM accumulated in the PM removal filter 56b is oxidized and removed (combusted). As a result, the PM removal filter 56b is regenerated. Details of the regeneration of the PM removal filter 56b will be described later.

  One end of a third exhaust pipe 58 is connected to the outlet portion of the exhaust treatment device 56. The other end of the third exhaust pipe 58 is connected to an additional exhaust treatment device, a muffler or the like that removes a specific component from the exhaust gas such as a catalyst. Therefore, the exhaust discharged from the turbine 36 is discharged outside the vehicle via the second exhaust pipe 54, the exhaust treatment device 56, the third exhaust pipe 58, various catalysts, a muffler, and the like. It is assumed that the other end of the third exhaust pipe 58 is open to the atmosphere.

  The intake manifold 28 and the exhaust manifold 50 are connected by the EGR device 60 without passing through the engine block 2. The EGR device 60 includes an EGR valve 62 and an EGR passage 66. One end of the EGR passage 66 is connected to the intake manifold 28, and the other end of the EGR passage 66 is connected to the exhaust manifold 50. The EGR valve 62 is provided in the middle of the EGR passage 66. The EGR passage 66 may be provided with an EGR cooler that is a water-cooled or air-cooled heat exchanger that cools the EGR gas flowing through the EGR passage 66.

  The EGR valve 62 adjusts the flow rate of EGR gas flowing through the EGR passage 66 in accordance with a control signal from the control device 200. The exhaust gas in the exhaust manifold 50 is returned to the intake side as EGR gas via the EGR device 60, whereby the combustion temperature in the cylinder is lowered and the amount of NOx generated is reduced.

  One end of the bypass passage 14 is connected to a connection position between the second intake pipe 24 and the third intake pipe 27. The other end of the bypass passage 14 is connected to the second exhaust pipe 54. A bypass valve 12 is provided in the middle of the bypass passage 14.

  The bypass valve 12 is an on-off valve whose opening degree is adjusted in accordance with a control signal from the control device 200. The flow rate of the air flowing through the bypass passage 14 is adjusted by adjusting the opening degree of the bypass valve 12.

  The supercharger 30 includes a compressor 32 and a turbine 36. A compressor wheel is housed in the housing of the compressor 32, and a turbine wheel (both not shown) is housed in the housing of the turbine 36. The compressor wheel and the turbine wheel are connected by a connecting shaft (not shown) and rotate integrally. Therefore, the compressor wheel is rotationally driven by the energy of the exhaust gas supplied to the turbine wheel.

  The operation of the engine 1 is controlled by the control device 200. The control device 200 includes a CPU (Central Processing Unit) that performs various processes, a ROM (Read Only Memory) that stores programs and data, and a RAM (Random Access Memory) that stores processing results of the CPU, and the like, Input / output ports (both not shown) for exchanging information with the outside. The sensors described above (for example, the intake pressure sensor 18, the differential pressure sensor 56c, the engine speed sensor 202, the air flow meter 208, etc.) are connected to the input port. Devices to be controlled (for example, a plurality of injectors 16, an intake throttle valve 10, a bypass valve 12, etc.) are connected to the output port.

  The control device 200 controls various devices so that the engine 1 is in a desired operation state based on signals from the sensors and devices, and a map and a program stored in the memory. Various controls are not limited to processing by software, and can be processed by dedicated hardware (electronic circuit). Further, the control device 200 has a built-in timer circuit (not shown) for measuring time.

  The intake pressure sensor 18 detects the pressure in the intake manifold 28. The intake pressure sensor 18 transmits a signal indicating the detected pressure to the control device 200.

  The differential pressure sensor 56c is a differential pressure (relative pressure) between the pressure in the exhaust pipe between the oxidation catalyst 56a and the PM removal filter 56b and the pressure in the exhaust pipe between the PM removal filter 56b and the third exhaust pipe 58. Is transmitted to the control device 200.

  The engine rotation speed sensor 202 detects the rotation speed of the crankshaft of the engine 1 as the engine rotation speed NE. The engine speed sensor 202 transmits a signal indicating the detected engine speed NE to the control device 200.

  The atmospheric pressure sensor 204 detects atmospheric pressure. The atmospheric pressure sensor 204 transmits a signal indicating the detected atmospheric pressure to the control device 200.

  The air flow meter 208 detects a flow rate (intake air amount) Qin of fresh air introduced into the first intake pipe 22. The air flow meter 208 transmits a signal indicating the detected intake air amount Qin to the control device 200.

  In the exhaust treatment device 56 of the engine 1 having the above-described configuration, when the amount of PM accumulated in the PM removal filter 56b increases, the filter portion of the PM removal filter 56b may be clogged and the function may deteriorate. . Therefore, the control device 200 performs regeneration control for regenerating the PM removal filter 56b.

  More specifically, the control device 200 acquires the amount of PM accumulated in the PM removal filter 56b. For example, the control device 200 estimates the amount of accumulated PM based on the differential pressure detected by the differential pressure sensor 56c (the PM removal filter 56b is closed by PM). The control device 200 executes regeneration control when the estimated amount of accumulated PM exceeds the regeneration determination value. At this time, the control device 200 sets, for example, a flag indicating that the regeneration control is being executed to an on state.

  When the regeneration control is executed, the control device 200 starts fuel addition from the fuel addition device. In the exhaust treatment device 56, when fuel is added to the exhaust gas from the fuel addition device, the added fuel reacts with the oxidation catalyst 56a, and the temperature of the exhaust gas is raised by the reaction heat. Then, when the exhaust gas having reached a high temperature flows into the PM removal filter 56b, the temperature of the PM removal filter 56b is raised to a temperature within a temperature range (about 600 ° C. to 700 ° C.) in which the PM removal filter 56b can be regenerated. The PM in the PM removal filter 56 is burned. The control device 200 counts the elapsed time when the temperature of the PM removal filter 56b is within a temperature range in which the regeneration of the PM removal filter 56b can be performed, and the total of the counted elapsed time is a predetermined regeneration end time. Is exceeded, it is determined that regeneration of the PM removal filter 56b has been completed. At this time, the control device 200 sets, for example, a flag indicating that the regeneration control is being executed to an off state.

  By the way, during such regeneration of the PM removal filter 56b, the operating condition of the engine 1 may change to an operating condition with a low intake air amount such as idle operation.

  FIG. 2 is a diagram showing the relationship between the engine speed and the load. The vertical axis in FIG. 2 indicates the load of the engine 1, and the horizontal axis in FIG. 2 indicates the engine speed NE. Each of the slanted thin broken lines in FIG. 2 represents an equal air amount line. The plurality of equal air amount lines in FIG. 2 indicate that an equal air amount line with a higher intake air amount Qin is arranged as it goes to the upper right in FIG.

  For example, when the user releases the depression of the accelerator pedal, the load on the engine 1 and the engine speed NE decrease, and the position on the graph in FIG. , The operating region of the engine 1) may shift to the B ′ region indicated by the hatched region in FIG.

  This B ′ region includes an equal air amount line (thick broken line in FIG. 2) of the lower limit intake air amount Qin (0), a horizontal axis in FIG. 2, and a line where engine speed NE = lower limit value NE (0) ( This is a region surrounded by a thick solid line in FIG. 2 and is a predetermined operation region where the load is low and the rotation speed is low. In this operating region, the operating condition is a low intake air amount in which the intake air amount Qin is lower than the lower limit intake air amount Qin (0). When the operating region of the engine 1 shifts to the B ′ region, the intake air amount Qin decreases, so the flow rate of the gas flowing through the PM removal filter 56b also decreases. In particular, when the intake air amount Qin is lower than the lower limit intake air amount Qin (0) shown by the thick broken line in FIG. 2, heat is accumulated in the PM removal filter 56b due to a decrease in the flow rate of the gas flowing through the PM removal filter 56b. In some cases, the temperature of the PM removal filter 56b rapidly rises due to insufficient heat dissipation.

  Therefore, for example, it may be possible to prevent the operating range of the engine 1 from shifting to the B ′ region by increasing the lower limit value of the engine speed NE to NE (1) higher than NE (0). There is a problem that fuel consumption increases due to an increase in the lower limit value of the engine speed NE. In addition, it is conceivable to send intake air to the exhaust side. However, when components such as a heater and a pump for temperature adjustment and flow rate adjustment are separately provided, there arises a problem that the manufacturing cost increases.

  Therefore, in the present embodiment, the control device 200 changes the operating state of the engine 1 to a predetermined operating state with a low load and a low rotational speed (that is, the B ′ region) during regeneration of the PM removal filter 56b. When shifting, the differential pressure between the first pressure in the bypass passage 14 and the second pressure in the second intake pipe 24 on the supercharger 30 side of the connection position between the second intake pipe 24 and the bypass passage 14. And the flow rate of the air flowing through the bypass passage 14 using the differential pressure between the third pressure and the second pressure in the third intake pipe 27 closer to the engine 1 than the connection position, and the PM removal filter 56b It is assumed that the opening degree of the bypass valve 12 is adjusted so that the flow rate of the gas flowing through the flow rate becomes a flow rate that suppresses overheating of the PM removal filter 56b.

  If it does in this way, the air supercharged by the supercharger 30 which operates by the exhaust energy before the operating area of the engine 1 shifts to the B ′ area will be removed from the second intake pipe 24 via the bypass passage 14. It flows through the second exhaust pipe 54 upstream of the filter 56b. As a result, the flow rate of the gas flowing through the PM removal filter 56b can be increased. In particular, since the amount of air in the bypass passage 14 can be accurately estimated using the first pressure, the second pressure, and the third pressure, the gas flow rate that flows through the PM removal filter 56b causes the PM removal filter 56b to overheat. The opening degree of the bypass valve 12 can be adjusted with high accuracy so that the flow rate is suppressed. Thereby, the rapid increase in the temperature of the PM removal filter 56b can be suppressed.

  Below, with reference to FIG. 3, the control process performed with the control apparatus 200 in this Embodiment is demonstrated. FIG. 3 is a flowchart showing a control process executed by the control device 200. The processing shown in this flowchart is called and executed from a main routine (not shown) at every predetermined control cycle.

  In step (hereinafter, step is described as S) 100, control device 200 determines whether or not PM removal filter 56b is being regenerated. For example, when the flag indicating that the regeneration control is being executed is on, the control device 200 determines that the PM removal filter 56b is being regenerated. If it is determined that PM removal filter 56b is being regenerated (YES in S100), the process proceeds to S102.

  In S102, control device 200 determines whether or not the operating region of engine 1 is within the B 'region. Since the B ′ region is as described above, detailed description thereof will not be repeated. When the position on the graph of FIG. 2 specified by the engine speed NE and the load (for example, calculated from the command value of the fuel injection amount) is within the B ′ region, the control device 200 operates the engine 1. Is in the B ′ region. If it is determined that the operation region of engine 1 is within the B ′ region (YES in S102), the process proceeds to S104.

  In S104, control device 200 controls bypass valve 12 so that the opening degree of bypass valve 12 becomes the base opening degree. The base opening is a predetermined opening. For example, an opening (for example, 40% to 60%) at which a change in the flow rate of air in the bypass passage 14 increases with respect to a change in the opening of the bypass valve 12 (a change in the angle of the valve body) is set as the base opening. May be.

  In S106, control device 200 determines whether or not intake air amount Qin is smaller than lower limit intake air amount Qin (0). If it is determined that intake air amount Qin is smaller than lower limit intake air amount Qin (0) (YES in S106), the process proceeds to S108.

  In S108, control device 200 calculates the pressure at point C (first pressure). As shown in FIG. 1, point C is a predetermined position in the bypass passage 14 on the side of the bypass passage 14 with respect to the connection position where one end of the bypass passage 14 and one end of the second intake pipe 24 are connected. The control device 200 calculates the pressure at point C based on the pressure detected by the differential pressure sensor 56c, the pressure detected by the atmospheric pressure sensor 204, and the opening degree of the bypass valve 12.

  More specifically, the control device 200 estimates the pressure loss in the bypass passage 14 from the opening degree of the bypass valve 12. The control device 200 estimates the pressure loss corresponding to the current opening degree from the current opening degree of the bypass valve 12 using, for example, a map showing the relationship between the opening degree of the bypass valve 12 and the pressure loss. For example, the control device 200 estimates the pressure at the point C by adding the estimated pressure loss to the pressure detected by the differential pressure sensor 56c and the atmospheric pressure detected by the atmospheric pressure sensor 204.

  For example, the control device 200 may estimate the opening degree of the bypass valve 12 based on the control value of the bypass valve 12, or may detect the opening degree of the bypass valve 12 using an opening sensor (not shown). May be.

  In S110, control device 200 calculates a pressure at point D (third pressure). As shown in FIG. 1, point D is a predetermined position in the third intake pipe 27 closer to the engine 1 than the connection position between the bypass passage 14 and the second intake pipe 24 described above. The point D is also a position between the connection position and the intake throttle valve 10. For example, the control device 200 calculates the pressure at the point D based on the pressure in the intake manifold 28 detected by the intake pressure sensor 18 and the opening of the intake throttle valve 10.

  More specifically, the control device 200 estimates the pressure loss in the third intake pipe 27 from the opening of the intake throttle valve 10. For example, the control device 200 estimates the pressure loss corresponding to the current opening degree from the current opening degree of the intake throttle valve 10 using a map indicating the relationship between the opening degree of the intake throttle valve 10 and the pressure loss. For example, the control device 200 estimates the pressure at the point D by adding the estimated pressure loss to the pressure detected by the intake pressure sensor 18.

  The control device 200 may estimate the opening of the intake throttle valve 10 based on, for example, the control value of the intake throttle valve 10 or may open the intake throttle valve 10 using an opening sensor (not shown). The degree may be detected.

  In S112, control device 200 calculates the pressure at point E (second pressure). Point E is a predetermined position in the second intake pipe 24 on the supercharger 30 side than the connection position between the bypass passage 14 and the second intake pipe 24 described above. The control device 200 estimates the rotational speed of the supercharger 30 based on, for example, the engine rotational speed NE and the fuel amount (fuel injection amount command value) supplied to the engine 1. The control device 200 estimates the supercharging pressure based on the estimated rotation speed of the supercharger 30, and calculates it as the pressure at the point E. The control device 200 uses, for example, a map indicating the relationship among the engine speed NE, the fuel injection amount, and the rotational speed of the supercharger 30 to determine the current supercharger 30 from the current engine speed NE and the fuel injection amount. Is estimated. Similarly, the control device 200 estimates the current supercharging pressure from the rotational speed of the supercharger 30 estimated using a map indicating the relationship between the rotational speed of the supercharger 30 and the supercharging pressure.

  In S114, control device 200 determines the flow rate of air flowing through bypass passage 14 from the differential pressure between the pressure at point C and the pressure at point E and the differential pressure between the pressure at point D and the pressure at point E ( Hereinafter, the first flow rate may be described). For example, the control device 200 determines what kind of air flows through the second intake pipe 24 from the differential pressure between the pressure at point C and the pressure at point E and the differential pressure between the pressure at point D and the pressure at point E. It is estimated whether the flow branches and flows into the third intake pipe 27 and the bypass passage 14 at a ratio, and the first flow rate is calculated from the estimated ratio and the flow rate of the air flowing through the second intake pipe 24.

  In S116, control device 200 adjusts the opening degree of bypass valve 12 so that the opening degree of bypass valve 12 becomes the target opening degree.

  More specifically, the control device 200 sets the target opening of the bypass valve 12 so that the flow rate flowing through the PM removal filter 56b becomes a flow rate that suppresses overheating of the PM removal filter 56b, for example. That is, the control device 200 suppresses overheating of the PM removal filter 56b by the sum of the first flow rate and the flow rate flowing from the turbine 36 of the supercharger 30 to the PM removal filter 56b (hereinafter referred to as the second flow rate). The target opening degree of the bypass valve 12 is set so as to be the lower limit value of the flow rate. The lower limit value of the flow rate that suppresses overheating of the PM removal filter 56b is a predetermined value that is adapted by experiments or the like.

  For example, the control device 200 calculates the flow rate of air flowing through the third intake pipe 27 from the estimated ratio described above and the flow rate of air flowing through the second intake pipe 24. The control device 200 uses a map or the like adapted in advance from the calculated flow rate of the air flowing through the third intake pipe 27 and the operating state of the engine 1 (for example, the engine speed NE and the fuel injection amount command value). To estimate the second flow rate. The control device 200 sets the target flow rate of the first flow rate by subtracting the second flow rate from the lower limit value of the flow rate that suppresses overheating of the PM removal filter 56b. The control device 200 sets a target opening degree at which the first flow rate becomes the target flow rate using a map or the like that is adapted in advance. The control device 200 controls the bypass valve 12 so that the opening degree of the bypass valve 12 becomes a set target opening degree.

  In S118, control device 200 determines whether or not the time during which the operation region of engine 1 is in the B 'region continues (hereinafter referred to as duration) is shorter than threshold value T. The threshold value T may be set, for example, based on the time until the supercharging pressure decreases by a predetermined amount when the bypass valve 12 continues to be open, or may be necessary via the bypass passage 14. It may be set based on the time until it becomes impossible to supply the air at a flow rate to the PM removal filter 56b. The threshold value T may be a predetermined value. If it is determined that the duration time is shorter than threshold value T (YES in S118), the process proceeds to S120.

  In S120, control device 200 determines whether or not the flow rate of air flowing through bypass passage 14 is greater than or equal to a threshold value. The threshold value may be, for example, the target flow rate described above, or a value obtained by adding a certain margin to the target flow rate. If it is determined that the flow rate of air flowing through bypass passage 14 is greater than or equal to the threshold value (YES in S120), the process proceeds to S122.

  In S122, control device 200 determines whether the operation region of engine 1 is the B region or whether regeneration of PM removal filter 56b has been completed. The B region is a region different from the B ′ region (the hatched region in FIG. 2) in the operation region of the engine 1 (the operation region in which the engine speed NE is NE (0) or more in FIG. 2). For example, when the position on the graph of FIG. 2 based on the engine speed NE and the load is within the B region, control device 200 determines that the operation region of engine 1 is the B region. Further, for example, when the flag indicating that the regeneration control of the PM removal filter 56b is being performed is in an off state, the control device 200 determines that the regeneration of the PM removal filter 56b has been completed. If it is determined that the operating region of engine 1 is the B region, or if it is determined that regeneration of PM removal filter 56b has been completed (YES in S122), the process proceeds to S124. .

  In S124, control device 200 controls bypass valve 12 so that bypass valve 12 is in the closed state (the opening degree is zero).

  In the above-described processing, when it is determined that the PM removal filter 56b is not being regenerated (NO in S100), or when it is determined that the operation region is not the B ′ region (NO in S102), this Processing is terminated.

  If the duration time is equal to or greater than threshold value T (NO in S118), the process proceeds to S126. In S126, control device 200 controls bypass valve 12 to be in a closed state (opening degree zero).

  In S128, control device 200 executes idle-up control. Specifically, control device 200 raises the lower limit value of engine speed NE in the idle state from NE (0) to NE (1).

  On the other hand, when it is determined that intake air amount Qin detected by air flow meter 208 is equal to or greater than lower limit intake air amount Qin (0) (NO in S106), the process proceeds to S130. In S130, control device 200 determines whether regeneration of PM removal filter 56b has been completed. If it is determined that regeneration of PM removal filter 56b has been completed (YES in S130), the process proceeds to S124. If not (NO in S130), the process returns to S106.

  Further, when it is determined that the flow rate of the air flowing through the bypass passage 14 is smaller than the threshold value (S120), or when it is determined that the operation region of the engine 1 is within the B ′ region (in S122). If it is determined that the regeneration of PM removal filter 56b has not ended (NO in S122), the process proceeds to S108.

  The operation of the control device 200 based on the above-described structure and flowchart will be described with reference to FIG. FIG. 4 is a diagram for explaining the operation of the control device 200. 4, the same components as those in FIG. 1 are given the same reference numerals. Therefore, detailed description thereof will not be repeated. For example, it is assumed that the bypass valve 12 is in a closed state.

  When the amount of PM accumulated in PM removal filter 56b exceeds the regeneration determination value, control device 200 performs regeneration control and sets a flag indicating that regeneration control is being performed to an on state (YES in S100). ).

  At this time, when the operation region of engine 1 is within region B (NO in S102), bypass valve 12 remains closed. Therefore, the air sucked from the first intake pipe 22 reaches the intake manifold 28 from the compressor 32 via the second intake pipe 24 and the third intake pipe 27 as shown by the solid line arrows in FIG. It is burned together with fuel in the cylinder 4. Exhaust gas discharged from the cylinder 4 flows to the turbine 36 via the exhaust manifold 50 and the first exhaust pipe 52, and after operating the supercharger 30, the exhaust processing device 56 via the second exhaust pipe 54. And is discharged to the third exhaust pipe 58.

  On the other hand, for example, when the driver releases the accelerator pedal and the operating region of engine 1 shifts to the B ′ region (YES in S102), bypass valve 12 is opened at the base opening (S104). ).

  As a result, the air sucked from the first intake pipe 22 passes from the second intake pipe 24 to the third intake pipe 27 indicated by the solid line arrow in FIG. 4 and the bypass passage 14 indicated by the broken line arrow in FIG. Branch to the route to and circulate.

  When intake air amount Qin is smaller than lower limit intake air amount Qin (0) (YES in S106), pressure at point C is calculated (S108), pressure at point D is calculated (S110), and point E Is calculated (S112). Then, the flow rate of the air flowing through the bypass passage 14 is calculated from the differential pressure between the pressure at the point C and the pressure at the point E and the differential pressure between the pressure at the point D and the pressure at the point E (S114). The opening degree of the bypass valve 12 is adjusted so as to reach the target opening degree set based on the flow rate of the air that has been set (S116). Thereby, since the flow volume which distribute | circulates to PM removal filter 56b turns into the flow volume which suppresses overheating of PM removal filter 56b, the rapid rise of the temperature of PM removal filter 56b is suppressed. When the duration in region B ′ is shorter than threshold value T (YES at S118), the flow rate of air flowing through the bypass passage is above the threshold value (YES at S120), and PM When regeneration of removal filter 56b ends (YES in S122), bypass valve 12 is controlled to be closed (S124). If duration time in region B ′ is equal to or greater than threshold value T (NO in S118), bypass valve 12 is controlled to be closed (S126), and idle-up control is executed. (S128).

  As described above, according to the exhaust treatment apparatus according to the present embodiment, when the operation region of the engine 1 shifts to the B ′ region during regeneration of the PM removal filter 56b, the bypass valve 12 is opened, so that B The air supercharged by the supercharger 30 that operates by the exhaust energy before shifting to the region flows from the second intake pipe 24 to the second exhaust pipe 54 via the bypass passage 14. As a result, the flow rate of the gas flowing through the PM removal filter 56b can be increased. In particular, since the amount of air in the bypass passage 14 can be accurately estimated using the first pressure, the second pressure, and the third pressure, the gas flow rate that flows through the PM removal filter 56b causes the PM removal filter 56b to overheat. The opening degree of the bypass valve 12 can be adjusted with high accuracy so that the flow rate is suppressed. Thereby, the rapid increase in the temperature of the PM removal filter 56b can be suppressed. In addition, since the operating state of the engine 1 is not changed so that the fuel consumption is deteriorated and parts such as a heater are not separately provided, an increase in fuel consumption and manufacturing cost can be suppressed. Therefore, it is possible to provide an exhaust treatment device that suppresses a rapid increase in temperature during regeneration of the PM removal filter without increasing fuel consumption and manufacturing cost under operating conditions of a low intake air amount.

  Further, since the regeneration of the PM removal filter can be continued even when the operation region of the engine 1 is within the B ′ region, the operation region of the engine 1 where the PM removal filter can be regenerated can be expanded.

  Furthermore, when the operating region of the engine 1 shifts to the B ′ region, the air can be quickly circulated in the bypass passage 14 by setting the opening of the bypass valve 12 to the base opening. A rapid increase in the temperature of the removal filter 56b can be suppressed.

  Further, by adjusting the opening degree of the bypass valve 12 so that the sum of the first flow rate and the second flow rate becomes a flow rate that suppresses overheating of the PM removal filter 56b, the flow rate of the gas flowing through the PM removal filter 56b is reduced. A decrease in the temperature can be suppressed, and a rapid increase in the temperature of the PM removal filter 56b can be suppressed.

  Further, the pressure loss based on the opening degree of the bypass valve 12, the operating state of the engine 1 (command value of the engine speed NE and the fuel injection amount), and the pressure loss based on the opening degree of the intake throttle valve 10 are taken into consideration. The first pressure, the second pressure, and the third pressure can be estimated with high accuracy by calculating the pressure, the second pressure, and the third pressure, respectively.

  Furthermore, after the bypass valve 12 is opened, if the duration after the operation state of the engine 1 shifts to the region B ′ during regeneration of the PM removal filter 56b becomes a time equal to or longer than the threshold value T, By closing the bypass valve 12 when the operating state shifts to the B region and / or when regeneration of the PM removal filter 56b is completed, the open state of the bypass valve 12 is unnecessarily continued. Since it can suppress that it is carried out, the fall of supercharging pressure can be suppressed.

Hereinafter, modified examples will be described.
In the above-described embodiment, the turbine 36 has been described as having turbine blades. However, in addition to the turbine blade, the turbine 36 may include a vane that changes a flow rate of exhaust gas flowing through the turbine blade. For example, when the PM removal filter 56b is being regenerated and the operation region of the engine 1 shifts to the B ′ region, the control device 200 performs vanes so that the flow rate of the exhaust gas flowing through the turbine blades becomes high. Control may be performed using an actuator or the like.

  Furthermore, in the above-described embodiment, the control device 200 is described as setting the target flow rate of the first flow rate by subtracting the second flow rate from the lower limit value of the flow rate that suppresses overheating of the PM removal filter 56b. However, for example, the lower limit value of the flow rate that suppresses overheating of the PM removal filter 56b may be set as the target flow rate of the first flow rate, or the lower limit intake air amount Qin (0) is set as the target flow rate. May be. Even in this case, the flow rate of the gas flowing through the PM removal filter 56b can be set to a flow rate that suppresses overheating of the PM removal filter 56b.

  Furthermore, in the above-described embodiment, the control device 200 is described as setting the target flow rate of the first flow rate by subtracting the second flow rate from the lower limit value of the flow rate that suppresses overheating of the PM removal filter 56b. However, the target flow rate may be set in consideration of a delay time caused by the difference in the length of the gas flow path when the first flow rate and the second flow rate change.

  Further, in the above-described embodiment, the rotational speed of the supercharger 30 is calculated from the engine rotational speed NE and the command value of the fuel injection amount, and the pressure at the point E (the first pressure is calculated from the calculated rotational speed of the supercharger 30). However, for example, the pressure at point E may be calculated directly from the engine speed NE and the command value for the fuel injection amount using a map or the like.

  Further, in the above-described embodiment, the bypass valve 12 has been described as being provided in the bypass passage 14. For example, the bypass valve 12 is provided at a connection position between one end of the bypass passage 14 and one end of the second intake pipe 24. A three-way valve may be used. In this case, for example, when the operating region of the engine 1 is the B region, the three-way valve is configured such that the air flowing from the second intake pipe 24 does not flow to the bypass passage 14 and the second intake pipe. 24 and the third intake pipe 27 are controlled by the control device 200 so as to be shut off. Further, the three-way valve is, for example, a second ratio in which the flow rate of the gas flowing through the PM removal filter 56b becomes a flow rate that suppresses overheating of the PM removal filter 56b when the operation region of the engine 1 shifts to the B ′ region. The controller 200 controls the air flowing from the intake pipe 24 to branch into the bypass passage 14 and the third intake pipe 27.

  Furthermore, in the above-described embodiment, the control device 200 has been described as estimating the PM accumulation amount based on the differential pressure detected by the differential pressure sensor 56c. An estimated value of PM emission from a plurality of cylinders 4 is calculated from operating conditions (for example, engine speed NE, fuel injection amount command value, intake air amount Qin, etc.), and the calculated emission amount estimate is The accumulation amount of PM may be acquired by integrating.

  Further, in the above-described embodiment, the PM removal filter 56b is regenerated by adding fuel to the exhaust gas from the fuel addition device. For example, the exhaust gas is discharged to the exhaust gas by post injection from an injector provided in the cylinder 4. The PM removal filter 56b may be regenerated by adding fuel.

  Further, in the above-described embodiment, the exhaust treatment device 56 has been described as including the differential pressure sensor 56c that detects the differential pressure before and after the PM removal filter 56b. For example, the first detection element of the differential pressure sensor 56c includes It is good also as a structure which provides a pressure sensor in each of the position provided and the position where a 2nd detection element is provided.

In addition, you may implement combining the above-mentioned modification, all or one part.
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 engine, 2 engine block, 4 cylinder, 12 bypass valve, 14 bypass passage, 22, 24, 27 intake pipe, 28 intake manifold, 30 turbocharger, 32 compressor, 36 turbine, 50 exhaust manifold, 52, 54, 58 Exhaust pipe, 56 Exhaust treatment device, 56a Oxidation catalyst, 56b PM removal filter, 56c Differential pressure sensor, 60 EGR device, 62 EGR valve, 66 EGR passage, 200 Controller, 202 Engine speed sensor, 204 Atmospheric pressure sensor, 208 Air flow meter.

Claims (7)

An exhaust passage connected to the engine and through which exhaust flows;
A filter provided in the exhaust passage and collecting particulate matter contained in the exhaust gas flowing through the exhaust passage;
An intake passage connected to the engine and through which intake air flows;
A supercharger that supercharges intake air flowing through the intake passage using energy of exhaust gas flowing through the exhaust passage;
A bypass passage connecting a portion of the intake passage through which the intake air supercharged by the supercharger flows and a portion of the exhaust passage between the supercharger and the filter;
An on-off valve capable of adjusting the flow rate of air flowing through the bypass passage;
A control device for adjusting the opening of the on-off valve;
In the bypass passage, when the operating state of the engine shifts to a predetermined operating state with a low load and a low rotational speed during the regeneration for burning the particulate matter deposited on the filter, Of the first pressure of the engine, the pressure difference between the second pressure in the intake passage on the supercharger side relative to the connection position of the intake passage and the bypass passage, and the intake air on the engine side of the connection position. A flow rate at which the flow rate of air flowing through the bypass passage is estimated using a differential pressure between the third pressure in the passage and the second pressure, and the flow rate of gas flowing through the filter suppresses overheating of the filter. An exhaust treatment device that adjusts the opening of the on-off valve so that   The control device adjusts the opening degree of the on-off valve after setting the opening degree of the on-off valve to a predetermined base opening degree when the operating state of the engine shifts to the predetermined operating state. The exhaust treatment device according to claim 1.   The controller opens the on-off valve so that the sum of the flow rate of gas flowing from the exhaust passage to the filter and the flow rate of air flowing through the bypass passage becomes a flow rate that suppresses overheating of the filter. The exhaust treatment device according to claim 1, wherein the exhaust gas treatment device is adjusted. The exhaust treatment device further includes an exhaust pressure detection unit that detects a pressure in the exhaust passage closer to the supercharger than the filter,
The exhaust control device according to claim 1, wherein the control device estimates the first pressure based on a pressure detected by the exhaust pressure detection unit and an opening degree of the on-off valve.   The exhaust control device according to any one of claims 1 to 4, wherein the control device estimates the second pressure based on a rotational speed of the engine and a fuel amount supplied to the engine. The exhaust treatment device includes:
An intake pressure detection unit that detects a pressure in the intake passage on the engine side of the connection position;
An intake throttle valve provided in the intake passage between the connection position and the intake pressure detection unit,
The exhaust control device according to any one of claims 1 to 5, wherein the control device estimates the third pressure based on a pressure detected by the intake pressure detection unit and an opening of the intake throttle valve.   When the predetermined time has elapsed after the engine operating state shifts to the predetermined operating state during regeneration of the filter after the opening / closing valve is opened, the control device The on-off valve is closed when at least one of an operation state that is different from the predetermined operation state and a case where regeneration of the filter is completed. An exhaust treatment apparatus according to claim 1.

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