JP6769415B2 - Exhaust treatment device - Google Patents

Description

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

An exhaust treatment device is provided in the exhaust pipe of the engine in order to purify particulate matter (PM: Particulate Matter) in the exhaust of a diesel engine or the like. This exhaust treatment device includes, for example, a PM removal filter that collects particulate matter and an oxidation catalyst (DOC: Diesel Oxidation Catalyst) that is arranged upstream of the exhaust flow from the PM removal filter. If the amount of particulate matter deposited in the PM removal filter increases, the filter will become clogged and the exhaust gas purification function will deteriorate. Therefore, by raising the temperature of the PM removal filter, the collected particulate matter will be burned to form a filter. The so-called PM removal filter is regenerated.

In the regeneration of the PM removal filter, fuel is added to the exhaust gas, the added fuel is reacted with an oxidation catalyst, and the heat of the reaction causes the exhaust gas to reach a temperature range (about 600 ° C. to 700 ° C.) at which the PM removal filter can be regenerated. Raise the temperature. Then, the hot exhaust gas circulates through the PM removal filter, so that the PM in the PM removal filter burns.

If the operating conditions of the engine change and the flow rate of the exhaust gas decreases during the regeneration of the PM removal filter, the temperature of the PM removal filter may rise sharply.

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 merging it with the exhaust manifold.

Japanese Unexamined Patent Publication No. 2003-20726

However, in the above-mentioned Patent Document 1, a heater for heating the air is separately provided in the pipe connecting the intake pipe through which the supercharged air flows and the exhaust manifold, which causes a problem that the manufacturing cost increases. Occurs. It is also conceivable to change the operating conditions of the engine so as to suppress the decrease in the exhaust flow rate, but 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-mentioned problems, and an object of the present invention is to cause 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 to provide an exhaust treatment apparatus which suppresses.

The exhaust treatment device according to a certain aspect of the present invention includes an exhaust passage connected to the engine and through which the exhaust flows, a filter provided in the exhaust passage and collecting particulate matter contained in the exhaust flowing through the exhaust passage. It is supercharged by an intake passage that is connected to the engine and the intake air flows, a supercharger that supercharges the intake air that flows through the intake passage using the energy of the exhaust that flows through the exhaust passage, and a supercharger that is one of the intake passages. A bypass passage that connects the portion where the intake air is circulated and the portion of the exhaust passage between the supercharger and the filter, and an on-off valve that can adjust the flow rate of the air that circulates in the bypass passage. It is equipped with a control device for adjusting the opening degree of the on-off valve. The control device applies the first pressure in the bypass passage when the operating state of the engine shifts to a predetermined operating state of low load and low rotation speed during regeneration by burning the particulate matter deposited on the filter. , The differential pressure between the second pressure in the intake passage on the supercharger side of the connection position between the intake passage and the bypass passage, and the third pressure and the second pressure in the intake passage on the engine side from the connection position. The flow rate of the air flowing through the bypass passage is estimated using the differential pressure, and the opening degree 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 the regeneration of the filter, the on-off valve is opened to operate with the exhaust energy before the transition 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 estimated with high accuracy using the first pressure, the second pressure, and the third pressure, the gas flow rate flowing through the filter should be a flow rate that suppresses overheating of the filter. The opening degree of the on-off valve can be adjusted with high accuracy. As a result, it is possible to suppress a rapid rise in the temperature of the filter. Further, since the operating state of the engine is not changed so as to deteriorate the fuel consumption and parts such as a heater are not separately provided, it is possible to suppress an increase in fuel consumption and manufacturing cost.

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

In this way, by opening the on-off valve until the opening of the on-off valve reaches a predetermined base opening, air can be quickly circulated in the bypass passage, so that a sudden rise 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 in the bypass passage is a flow rate that suppresses overheating of the filter. To do.

In this way, when the operating state of the engine shifts to a predetermined operating state during regeneration of the filter, the flow rate of the gas flowing through the filter can be increased, and a sudden rise in the temperature of the filter can be suppressed.

More preferably, the exhaust treatment device further includes an exhaust pressure detecting unit that detects the pressure in the exhaust passage on the supercharger side of 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 controller 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 treatment device is an intake throttle valve provided in the intake passage between the intake pressure detection unit that detects the pressure in the intake passage on the engine side of the connection position and the connection position and the intake pressure detection unit. And further prepare. The control device estimates the third pressure based on the pressure detected by the intake pressure detection unit and the opening degree 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 degree of the intake throttle valve.

More preferably, the control device opens the on-off valve, and when a predetermined time elapses after the engine operating state shifts to a predetermined operating state during filter regeneration, the engine operating state. The on-off valve is closed when the operating state is different from the predetermined operating state and at least one of the cases where the regeneration of the filter is completed.

In this way, it is possible to prevent the on-off valve from being unnecessarily continued to be open, so that it is possible to suppress a decrease in the boost pressure.

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 the schematic structure of the engine in this embodiment. It is a figure which shows the relationship between the engine speed and a load. It is a flowchart which shows the control process executed by a control device. It is a figure for demonstrating operation of a control device.

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

FIG. 1 is a diagram showing a schematic configuration of an engine 1 according to the present embodiment. In the present embodiment, the engine 1 may be a diesel engine, and the common rail type diesel engine will be described below 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. The control device 200, the engine rotation speed sensor 202, the atmospheric pressure sensor 204, and the air flow meter 208 are provided.

A plurality of cylinders 4 are formed in the engine block 2, and a plurality of injectors (not shown) are provided in each of the plurality of cylinders 4. In the present embodiment, the engine 1 will be described by taking an in-line 4-cylinder engine as an example, but may be an engine having another cylinder layout (for example, V type or 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 (neither 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 the control signal from the control device 200.

The air cleaner (not shown) removes foreign matter 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 turbocharger 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 by using the energy of the exhaust flowing through the first exhaust pipe 52, which will be described later, and supplies the air to the second intake pipe 24.

One end of the third intake pipe 27 is connected to the other end of the second intake pipe 24. The third intake pipe 27 may be provided with, for example, an intercooler which 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. An 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 the 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 turbocharger 30. Therefore, the exhaust gas 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 the 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 on the downstream side of the exhaust flow path (exhaust passage) with respect to the oxidation catalyst 56a. 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 56c is provided in the exhaust pipe between the PM removal filter 56b 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 made of, for example, ceramic or stainless steel. The collected PM is deposited in the PM removal filter 56b.

The oxidation catalyst 56a functions as a regeneration mechanism that burns and removes (regenerates) PM deposited on the PM removal filter 56b. When the exhaust gas is circulated, the oxidation catalyst 56a oxidizes nitrogen oxides (NOx) and carbon oxides (COx) in the circulated exhaust gas, and a fuel addition device is added to the exhaust gas on the upstream side of the oxidative catalyst 56a. Oxidizes the fuel if it contains fuel added from. An injector provided in each cylinder may be used as the fuel addition device. By performing post injection in the combustion stroke of each cylinder, fuel is added to the exhaust from the injector. The heat of reaction generated by the oxidation of the fuel raises the temperature of the exhaust gas passing through the oxidation catalyst 56a. 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. The details of the reproduction of the PM removal filter 56b will be described later.

One end of the third exhaust pipe 58 is connected to the outlet portion of the exhaust treatment device 56. An additional exhaust treatment device, a muffler, or the like that removes a specific component from the exhaust such as a catalyst is connected to the other end of the third exhaust pipe 58. Therefore, the exhaust gas discharged from the turbine 36 is discharged to the outside of 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 which 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 the EGR gas flowing through the EGR passage 66 in response to the 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, so that the combustion temperature in the cylinder is lowered and the amount of NOx produced is reduced.

One end of the bypass passage 14 is connected to the 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 according to a control signal from the control device 200. By adjusting the opening degree of the bypass valve 12, the flow rate of the air flowing through the bypass passage 14 is adjusted.

The supercharger 30 includes a compressor 32 and a turbine 36. The compressor wheel is housed in the housing of the compressor 32, and the turbine wheel (neither is 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 memory that includes a ROM (Read Only Memory) that stores programs and data, a RAM (Random Access Memory) that stores the processing results of the CPU, and the like. Includes input / output ports (neither shown) for exchanging information with the outside. The above-mentioned sensors (for example, intake pressure sensor 18, differential pressure sensor 56c, engine speed sensor 202, 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 operating state based on signals from each sensor and device, as well as maps and programs stored in memory. Note that various controls are not limited to software processing, but can also be processed by dedicated hardware (electronic circuits). Further, the control device 200 has a built-in timer circuit (not shown) for measuring the time.

The intake pressure sensor 18 detects the pressure inside 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 speed sensor 202 detects the speed of the crankshaft of the engine 1 as the engine speed NE. The engine speed sensor 202 transmits a signal indicating the detected engine speed NE to the control device 200.

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 the 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 configuration, if the amount of PM deposited in the PM removal filter 56b increases, the filter portion of the PM removal filter 56b may become clogged and its function may deteriorate. .. Therefore, the control device 200 executes regeneration control for reproducing the PM removal filter 56b.

More specifically, the control device 200 acquires the accumulated amount of PM in the PM removal filter 56b. The control device 200 estimates the accumulated amount of PM based on, for example, the differential pressure detected by the differential pressure sensor 56c (the closed state of the PM removal filter 56b by PM). The control device 200 executes regeneration control when the estimated amount of PM deposited exceeds the regeneration determination value. At this time, the control device 200 sets, for example, a flag indicating that the reproduction control is being executed to the 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 heat of the reaction raises the temperature of the exhaust gas. Then, the high temperature exhaust gas flows through the PM removal filter 56b, so that the temperature of the PM removal filter 56b rises to a temperature within the reproducible temperature range (about 600 ° C. to 700 ° C.) of the PM removal filter 56b. Then, the PM in the PM removal filter 56 is burned. The control device 200 counts the elapsed time in a state where the temperature of the PM removal filter 56b is within the reproducible temperature range of the PM removal filter 56b, and the total of the counted elapsed times is the predetermined playback end time. If it exceeds, it is determined that the regeneration of the PM removal filter 56b is completed. At this time, the control device 200 sets, for example, a flag indicating that the reproduction control is being executed to the off state.

By the way, during the regeneration of such a PM removal filter 56b, the operating conditions of the engine 1 may change to operating conditions of 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 of FIG. 2 shows the load of the engine 1, and the horizontal axis of FIG. 2 shows the engine speed NE. Each of the plurality of diagonal dashed lines in FIG. 2 indicates an equal air volume line. The plurality of isobaric lines of FIG. 2 indicate that the isobaric lines having a higher intake air amount Qin are arranged toward the upper right of FIG.

For example, when the user releases the depression of the accelerator pedal, the load of the engine 1 and the engine speed NE decrease, and the position on the graph of FIG. 2 specified by the load of the engine 1 and the engine speed NE (that is, the engine speed NE). , The operating region of the engine 1) may shift to the B'region shown by the shaded region in FIG.

In this B'region, the equal air amount line (thick broken line in FIG. 2) of the lower limit intake air amount Qin (0), the horizontal axis in FIG. 2, and the line where the engine speed NE = the lower limit value NE (0) ( It is a region surrounded by the thick solid line in FIG. 2), which is a predetermined operation region having a low load and a low rotation speed. 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 that the flow rate of the gas flowing through the PM removal filter 56b also decreases. In particular, when the intake air amount Qin is less than the lower limit intake air amount Qin (0) shown by the thick broken line in FIG. 2, heat is trapped in the PM removal filter 56b due to a decrease in the flow rate of the gas flowing through the PM removal filter 56b. The temperature of the PM removal filter 56b may rise sharply due to insufficient heat dissipation.

Therefore, for example, by raising the lower limit of the engine speed NE to NE (1) higher than NE (0), it is conceivable to prevent the operating region of the engine 1 from shifting to the B'region. There is a problem that fuel consumption increases due to an increase in the lower limit of the engine speed NE. It is also conceivable to send the intake air to the exhaust side, but if parts 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 (that is, the B'region) having a low load and a low rotation speed during the regeneration of the PM removal filter 56b. At the time of transition, 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 The flow rate of the air flowing through the bypass passage 14 is estimated using the pressure difference between the third pressure and the second pressure in the third intake pipe 27 on the engine 1 side of 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 above is a flow rate that suppresses overheating of the PM removal filter 56b.

In this way, the air supercharged by the supercharger 30 operated by the exhaust energy before the operating region of the engine 1 shifts to the B'region is removed from the second intake pipe 24 via the bypass passage 14. It flows to 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 estimated with high accuracy using the first pressure, the second pressure, and the third pressure, the gas flow rate flowing 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. As a result, it is possible to suppress a rapid rise in the temperature of the PM removal filter 56b.

The control process executed by the control device 200 according to the present embodiment will be described below with reference to FIG. FIG. 3 is a flowchart showing a control process executed by the control device 200. The process shown in this flowchart is called and executed from the main routine (not shown) at predetermined control cycles.

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

In S102, the control device 200 determines whether or not the operating region of the engine 1 is within the B'region. Since the B'region is as described above, the detailed description thereof will not be repeated. The control device 200 has an operating region of the engine 1 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. Is determined to be in the B'region. When it is determined that the operating region of the engine 1 is within the B'region (YES in S102), the process is transferred to S104.

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

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

In S108, the 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 bypass passage 14 side of 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, for example, the pressure loss corresponding to the current opening degree from the current opening degree of the bypass valve 12 by using 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 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.

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 detect the opening degree of the bypass valve 12 by using an opening degree sensor (not shown). You may.

In S110, the control device 200 calculates the pressure at point D (third pressure). As shown in FIG. 1, the point D is a predetermined position in the third intake pipe 27 on the engine 1 side of the connection position between the bypass passage 14 and the second intake pipe 24 described above. Point D is also a position between the connection position and the intake throttle valve 10. The control device 200 calculates the pressure at point D based on, for example, the pressure in the intake manifold 28 detected by the intake pressure sensor 18 and the opening degree 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 degree of the intake throttle valve 10. The control device 200 estimates, for example, the pressure loss corresponding to the current opening degree from the current opening degree of the intake throttle valve 10 by using a map showing the relationship between the opening degree of the intake throttle valve 10 and the pressure loss. The control device 200 estimates the pressure at point D by adding the estimated pressure loss to the pressure detected by the intake pressure sensor 18, for example.

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

In S112, the 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 of the connection position between the bypass passage 14 and the second intake pipe 24 described above. The control device 200 estimates the rotation speed of the turbocharger 30 based on, for example, the engine speed NE and the amount of fuel supplied to the engine 1 (command value of the fuel injection amount). 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 point E. The control device 200 uses, for example, a map showing the relationship between the engine speed NE, the fuel injection amount, and the speed of the supercharger 30 to obtain the current engine speed NE and the fuel injection amount from the current supercharger 30. Estimate the number of revolutions of. Similarly, the control device 200 estimates the current supercharging pressure from the estimated rotation speed of the supercharger 30 using a map showing the relationship between the rotation speed of the supercharger 30 and the supercharging pressure.

In S114, the control device 200 receives the flow rate of air flowing through the bypass passage 14 from the difference pressure between the pressure at point C and the pressure at point E and the pressure difference between the pressure at point D and the pressure at point E ( Hereinafter, it may be referred to as the first flow rate). In the control device 200, for example, what kind of air is flowing through the second intake pipe 24 from the difference pressure between the pressure at point C and the pressure at point E and the pressure difference between the pressure at point D and the pressure at point E. It is estimated whether the third intake pipe 27 and the bypass passage 14 are branched and circulated 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, the control device 200 adjusts the opening degree of the bypass valve 12 so that the opening degree of the bypass valve 12 becomes the target opening degree.

More specifically, the control device 200 sets the target opening degree of the bypass valve 12 so that, for example, the flow rate flowing through the PM removal filter 56b is a flow rate that suppresses overheating of the PM removal filter 56b. That is, in the control device 200, 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) suppresses overheating of the PM removal filter 56b. The target opening degree of the bypass valve 12 is set so as to reach the lower limit of the flow rate. The lower limit of the flow rate for suppressing overheating of the PM removal filter 56b is a predetermined value adapted by experiments or the like.

The control device 200 calculates, for example, the flow rate of the air flowing through the third intake pipe 27 from the above-mentioned estimated ratio and the flow rate of the air flowing through the second intake pipe 24. The control device 200 uses a map or the like preliminarily adapted from the calculated flow rate of air flowing through the third intake pipe 27 and the operating state of the engine 1 (for example, the command value of the engine speed NE and the fuel injection amount). The second flow rate is estimated. 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 by using a map or the like 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, the control device 200 determines whether or not the time during which the operating region of the engine 1 is in the B'region (hereinafter referred to as the duration) is shorter than the threshold value T. The threshold value T may be set based on, for example, the time until the boost pressure drops by a predetermined amount when the bypass valve 12 continues to be open, or is required via the bypass passage 14. It may be set based on the time until the flow rate of air cannot be supplied to the PM removal filter 56b. The threshold value T may be a predetermined value. If it is determined that the duration is shorter than the threshold value T (YES in S118), the process is transferred to S120.

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

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

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

In the above process, if it is determined that the PM removal filter 56b is not being regenerated (NO in S100), or if it is determined that the operating region is not in the B'region (NO in S102), this The process is terminated.

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

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

On the other hand, when it is determined that the intake air amount Qin detected by the air flow meter 208 is equal to or greater than the lower limit intake air amount Qin (0) (NO in S106), the process is transferred to S130. In S130, the control device 200 determines whether or not the reproduction of the PM removal filter 56b is completed. When it is determined that the regeneration of the PM removal filter 56b is completed (YES in S130), the process is transferred to S124. If not (NO in S130), processing is returned 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 operating region of the engine 1 is within the B'region (in S122). NO), or when it is determined that the regeneration of the PM removal filter 56b is not completed (NO in S122), the process is transferred to S108.

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

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

At this time, if the operating region of the engine 1 is within the B region (NO in S102), the 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 arrow in FIG. It is burned together with fuel in the cylinder 4. The exhaust gas discharged from the cylinder 4 is circulated to the turbine 36 via the exhaust manifold 50 and the first exhaust pipe 52, and after operating the supercharger 30, the exhaust treatment device 56 is passed through the second exhaust pipe 54. It is distributed to the third exhaust pipe 58 and discharged to the third exhaust pipe 58.

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

As a result, the air sucked from the first intake pipe 22 has a path from the second intake pipe 24 to the third intake pipe 27 shown by the solid arrow in FIG. 4 and the bypass passage 14 shown by the broken arrow in FIG. Branches and distributes along the route to.

When the intake air amount Qin is smaller than the lower limit intake air amount Qin (0) (YES in S106), the pressure at point C is calculated (S108), the pressure at point D is calculated (S110), and the pressure at point E is calculated. Pressure 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 C point and the pressure at the E point and the differential pressure between the pressure at the D point and the pressure at the E point (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 (S116). As a result, the flow rate flowing through the PM removal filter 56b becomes a flow rate that suppresses overheating of the PM removal filter 56b, so that a rapid rise in the temperature of the PM removal filter 56b is suppressed. When the duration in the B'region is shorter than the threshold value T (YES in S118), the flow rate of the air flowing through the bypass passage is above the threshold value (YES in S120), and PM When the regeneration of the removal filter 56b is completed (YES in S122), the bypass valve 12 is controlled to the closed state (S124). When the duration in the B'region is equal to or greater than the threshold value T (NO in S118), the bypass valve 12 is controlled to the closed state (S126), and idle-up control is executed. (S128).

As described above, according to the exhaust gas treatment device according to the present embodiment, when the operating region of the engine 1 shifts to the B'region during the regeneration of the PM removal filter 56b, the bypass valve 12 is opened, so that B The air supercharged by the supercharger 30 operated by the exhaust energy before the transition 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 estimated with high accuracy using the first pressure, the second pressure, and the third pressure, the gas flow rate flowing 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. As a result, it is possible to suppress a rapid rise in the temperature of the PM removal filter 56b. Further, since the operating state of the engine 1 is not changed so as to deteriorate the fuel consumption and parts such as a heater are not separately provided, it is possible to suppress an increase in fuel consumption and manufacturing cost. Therefore, it is possible to provide an exhaust treatment device that suppresses a rapid rise in temperature during regeneration of a PM removal filter under operating conditions with a low intake air amount without increasing fuel consumption and manufacturing cost.

Further, since the regeneration of the PM removal filter can be continued even when the operating region of the engine 1 is within the B'region, the operating region of the reproducible engine 1 of the PM removal filter can be expanded.

Further, when the operating region of the engine 1 shifts to the B'region, by setting the opening degree of the bypass valve 12 to the base opening degree, air can be quickly circulated in the bypass passage 14, so that PM It is possible to suppress a rapid rise in the temperature of the removal filter 56b.

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 is 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 increased. It is possible to suppress the decrease and suppress the rapid rise in the temperature of the PM removal filter 56b.

Further, in consideration of 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, the first By calculating the pressure, the second pressure, and the third pressure, respectively, the first pressure, the second pressure, and the third pressure can be estimated with high accuracy.

Further, when the duration after the operating state of the engine 1 shifts to the B'region during the regeneration of the PM removal filter 56b after opening the bypass valve 12 becomes a time of the threshold value T or more, the engine 1 By closing the bypass valve 12 when the operating state shifts to the B region and at least one of the cases where the regeneration of the PM removal filter 56b is completed, the open state of the bypass valve 12 continues unnecessarily. Since it can be suppressed, it is possible to suppress a decrease in the boost pressure.

Hereinafter, a modified example will be described.
In the above-described embodiment, the turbine 36 has been described as having a turbine blade, but may include a vane that changes the flow velocity of the exhaust gas flowing through the turbine blade in addition to the turbine blade. The control device 200 vanes so that the flow velocity of the exhaust gas flowing through the turbine blades increases, for example, when the PM removal filter 56b is being regenerated and the operating region of the engine 1 shifts to the B'region. It may be controlled by using an actuator or the like.

Further, 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 for suppressing overheating of the PM removal filter 56b. However, for example, the lower limit of the flow rate for suppressing 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) may be set as the target flow rate. You may. Even in this way, 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.

Further, 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 for suppressing overheating of the PM removal filter 56b. However, the target flow rate may be set in consideration of the delay time due to the difference in the length of the gas flow path when the first flow rate or the second flow rate changes.

Further, in the above-described embodiment, the rotation speed of the supercharger 30 is calculated from the engine rotation speed NE and the command value of the fuel injection amount, and the pressure at point E is calculated from the calculated rotation speed of the supercharger 30 (No. 2 Pressure) has been described, but for example, the pressure at point E may be calculated directly from the engine speed NE and the command value of 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, but is provided, for example, at a connection position between one end of the bypass passage 14 and one end of the second intake pipe 24. It may be a three-way valve. In this case, for example, when the operating region of the engine 1 is the B region, the three-way valve has a bypass passage 14 and a second intake pipe so that the air flowing from the second intake pipe 24 does not flow to the bypass passage 14. It is controlled by the control device 200 so as to shut off the 24 and the third intake pipe 27. Further, in the three-way valve, for example, when the operating region of the engine 1 shifts to the B'region, the flow rate of the gas flowing through the PM removal filter 56b becomes the flow rate that suppresses overheating of the PM removal filter 56b. The control device 200 controls the air flowing from the intake pipe 24 so as to branch into the bypass passage 14 and the third intake pipe 27.

Further, in the above-described embodiment, the control device 200 has been described as estimating the accumulated amount of PM based on the differential pressure detected by the differential pressure sensor 56c. For example, the control device 200 is the engine 1. Estimated values of PM emissions from a plurality of cylinders 4 are calculated from operating conditions (for example, engine speed NE, fuel injection amount command value, intake air amount Qin, etc.), and the calculated emission amount estimates are used. The accumulated amount of PM may be obtained 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. However, for example, the exhaust gas is produced 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 for detecting the differential pressure before and after the PM removal filter 56b. For example, the first detection element of the differential pressure sensor 56c is described. A pressure sensor may be provided at each of the position where the second detection element is provided and the position where the second detection element is provided.

The above-mentioned modification may be carried out in whole or in combination.
It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 engine, 2 engine blocks, 4 cylinders, 12 bypass valves, 14 bypass passages, 22, 24, 27 intake pipes, 28 intake manifolds, 30 superchargers, 32 compressors, 36 turbines, 50 exhaust manifolds, 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 control device, 202 engine rotation speed sensor, 204 atmospheric pressure sensor, 208 Air flow meter.

Claims (7)

An exhaust passage that is connected to the engine and allows exhaust to flow,
A filter provided in the exhaust passage and collecting particulate matter contained in the exhaust flowing through the exhaust passage,
An intake passage connected to the engine and through which 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.
A bypass passage connecting a portion of the intake passage to 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 that can adjust the flow rate of air flowing through the bypass passage,
A control device for adjusting the opening degree of the on-off valve is provided.
The control device is in the bypass passage when the operating state of the engine shifts to a predetermined operating state of low load and low rotation speed during regeneration of burning the particulate matter deposited on the filter. The difference pressure between the first pressure of the above and the second pressure in the intake passage on the supercharger side of the connection position between the intake passage and the bypass passage, and the intake on the engine side of the connection position. The flow rate of air flowing through the bypass passage is estimated using the differential pressure between the third pressure in the passage and the second pressure, and the flow rate of the gas flowing through the filter suppresses overheating of the filter. An exhaust treatment device that adjusts the opening degree of the on-off valve so as to be. When the operating state of the engine shifts to the predetermined operating state, 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. The exhaust treatment device according to claim 1. In the control device, the opening degree of the on-off valve is such 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 in the bypass passage is a flow rate for suppressing overheating of the filter. The exhaust treatment apparatus according to claim 1 or 2. The exhaust treatment device further includes an exhaust pressure detecting unit that detects the pressure in the exhaust passage on the supercharger side of the filter.
The exhaust treatment device according to any one of claims 1 to 3, wherein 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. The exhaust treatment device according to any one of claims 1 to 4, wherein the control device estimates the second pressure based on the rotation speed of the engine and the amount of fuel supplied to the engine. The exhaust treatment device is
An intake pressure detection unit that detects the pressure in the intake passage on the engine side of the connection position,
Further provided with an intake throttle valve provided in the intake passage between the connection position and the intake pressure detection unit.
The exhaust treatment device according to any one of claims 1 to 5, wherein the control device estimates the third pressure based on the pressure detected by the intake pressure detecting unit and the opening degree of the intake throttle valve. When the predetermined time elapses after the operating state of the engine shifts to the predetermined operating state during the regeneration of the filter after the on-off valve is opened, the control device of the engine of the engine. Any of claims 1 to 6, wherein the on-off valve is closed when the operating state is different from the predetermined operating state, or at least one of the cases where the regeneration of the filter is completed. Exhaust treatment device described in Crab.

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