JP2005061379A - Exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To monitor a self-regenerating filter (DPF) to rapidly cope with it at the occurrence of abnormality. <P>SOLUTION: This exhaust emission control device is provided with the self-regenerating diesel particulate filter (DPF) for collecting carbon particles included in exhaust gas exhausted from a diesel engine, and burning to eliminate the collected carbon particles by the reaction heat of a catalyst. The exhaust emission control device has a temperature detecting means for detecting exhaust gas temperature on the inlet side and exhaust gas temperature on the outlet side of the DPF respectively, and a monitoring means for monitoring the heated state of the DPF based on the difference between the detected exhaust gas temperature on the inlet side and exhaust gas temperature on the outlet side of the DPF. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exhaust gas purification apparatus, and more particularly to a self-regenerating diesel part that captures carbon particulates contained in exhaust gas discharged from a diesel engine and burns and removes the captured carbon particulates by reaction heat of a catalyst. The present invention relates to an exhaust gas purification apparatus provided with a curate filter.

  In recent years, environmental pollution due to carbon fine particles contained in exhaust gas (exhaust gas) discharged from a diesel engine has become serious. In order to solve this problem, in certain areas, mainly in the Tokyo metropolitan area, traveling is permitted unless the vehicle is equipped with a so-called particulate matter reduction device that captures carbon particulates from the exhaust gas of diesel engines. In addition, a vehicle that is not equipped with the particulate matter reduction device is about to be implemented with legislation so as to prohibit entry into the certain area described above.

BACKGROUND ART A diesel particulate filter (hereinafter referred to as “DPF”) as an element for capturing carbon fine particles from exhaust gas of a diesel engine is composed of an element that can capture carbon fine particles contained in the exhaust gas. When the DPF clogs the captured carbon fine particles, a heating combustion type in which the DPF is heated with an electric heater to burn and remove the carbon fine particles (refer to Patent Document 1), and platinum is used as a filter element. A catalyst composed of a noble metal such as (Pt), palladium (Pd) or rhodium (Rh) is supported to form a DPF, and the carbon fine particles captured by the DPF are combusted by reaction heat due to the oxidation reaction of HC and CO in the exhaust gas. There is a self-regenerative type that removes and regenerates (see Patent Document 2). This self-regenerating DPF does not require the provision of an electric heater such as a heating combustion type, and does not require an operation such as controlling the electric heater, and can control the temperature of exhaust gas when a diesel engine is driven. It has the feature that it can be used and played back.
JP-A-10-299454 Japanese Patent Laid-Open No. 11-253757

  However, in the exhaust gas purification apparatus provided with the self-regenerating DPF, the DPF has a property that the carbon particulates cannot be oxidized and removed unless the exhaust gas and the catalyst are in contact with each other within a predetermined contact temperature range. When the diesel engine is operated at a low speed such as idling for a long time, a predetermined contact temperature cannot be obtained and the DPF is clogged.

  That is, the self-regenerating DPF has excellent oxidation removal efficiency of carbon fine particles in a contact temperature range of 250 to 500 ° C., and this contact temperature is naturally obtained when a vehicle equipped with a diesel engine is running. It is done. Therefore, the DPF can self-regenerate without any problem during normal driving of the vehicle. However, when the vehicle is stopped and idling takes a long time, that is, when the diesel engine is put in low speed rotation for a long time, the exhaust gas temperature of the diesel engine becomes 200 ° C. or lower, and the self-regeneration function of the DPF decreases, DPF has a drawback that it only collects carbon fine particles and causes clogging. In addition, when such clogging occurs in the DPF, the exhaust system of the diesel engine is blocked, which causes a disadvantage of adversely affecting the output of the diesel engine itself.

  In addition, even when the DPF is clogged with carbon fine particles or when it does not progress to the clogged state, the presence of a large amount of unburned carbon fine particles in the exhaust system of the diesel engine Obviously, it is not preferable because there are many combustible carbon fine particles. And when an abnormal condition occurs that ignites carbon fine particles in the DPF for some reason, the abnormal condition is accurately grasped and the abnormal DPF is isolated and separated from the exhaust system of the diesel engine. It is also clear that appropriate measures need to be taken.

  Accordingly, the present invention has been made to eliminate the drawbacks of the conventional exhaust gas purification apparatus, and provides a first exhaust gas purification apparatus that can monitor the state of a self-regenerating DPF. The purpose is. A second object of the present invention is to provide an exhaust gas purifying apparatus capable of disconnecting a DPF in which an abnormality has occurred from an exhaust system of a diesel engine when an abnormal state occurs in the DPF. Yes. Another object of the present invention is to provide an exhaust gas purification apparatus that can prevent clogging of the DPF.

In order to achieve the above object, the exhaust gas purifying apparatus according to the present invention collects carbon fine particles contained in the exhaust gas discharged from a diesel engine, and the collected carbon fine particles. In the exhaust gas purification apparatus having a self-regenerating DPF that burns and removes the catalyst by the reaction heat of the catalyst, temperature detection means for detecting the exhaust gas temperature on the inlet side and the exhaust gas temperature on the outlet side of the DPF, respectively, Monitoring means for monitoring the heating state of the DPF based on the difference between the exhaust gas temperature on the inlet side and the exhaust gas temperature on the outlet side of the DPF.
In the exhaust gas purifying apparatus according to claim 2 of the present invention, the DPF is provided in one of the two paths formed between the two two-way valves, and the DPF is in a predetermined heating state by the monitoring means. When it is determined that the DPF is in operation, the two two-way valves are respectively operated to close one of the paths provided with the DPF, and exhaust gas discharged from the diesel engine is provided with the DPF. It is characterized by discharging through the other route that is not.
The exhaust gas purifying apparatus according to claim 3 of the present invention eliminates the sound generated from the diesel engine in the other path where the DPF is not provided, out of the two paths formed between the two two-way valves. The feature is that a silencer is provided.
In the exhaust gas purifying apparatus according to claim 4 of the present invention, the other path where the DPF is not provided among the two paths formed between the two two-way valves is, among the two two-way valves, A bypass path communicating with the atmosphere without passing through a two-way valve located on the downstream side of the exhaust gas flow is provided.
The exhaust gas purifying apparatus according to claim 5 of the present invention is provided with pressure detecting means for detecting the exhaust gas pressure on the inlet side of the DPF, and two two-way valves when the pressure detecting means detects a predetermined pressure or more. Each of which is operated to close one path where the DPF is provided, and exhaust gas discharged from the diesel engine is discharged via the other path where the DPF is not provided. Yes.
The exhaust gas purifying apparatus according to claim 6 of the present invention is provided with temperature detecting means for detecting the temperature of the exhaust gas before entering the two-way valve located upstream of the flow of the exhaust gas of the two two-way valves. It is characterized by.

The exhaust gas purifying apparatus according to claim 1 of the present invention includes temperature detection means for detecting the exhaust gas temperature on the inlet side of the DPF and the exhaust gas temperature on the outlet side, and the detected exhaust gas temperature on the inlet side and the outlet side of the DPF. Monitoring means for monitoring the heating state of the DPF based on the difference in exhaust gas temperature of the DPF, so that the operating state of the DPF can be monitored. For example, when abnormal combustion occurs in the DPF, the abnormal state is indicated. Can be detected.
In the exhaust gas purifying apparatus according to claim 2 of the present invention, the DPF is provided in one of the two paths formed between the two two-way valves, and the DPF is in a predetermined heating state by the monitoring means. When it is determined that the DPF is in operation, the two two-way valves are respectively operated to close one of the paths provided with the DPF, and exhaust gas discharged from the diesel engine is provided with the DPF. Since the exhaust gas is discharged through the other route, the DPF in which the abnormal state has occurred can be separated from the exhaust system of the diesel engine, and a passage of the exhaust system of the diesel engine can be secured.
The exhaust gas purifying apparatus according to claim 3 of the present invention eliminates the sound generated from the diesel engine in the other path where the DPF is not provided, out of the two paths formed between the two two-way valves. Since the silencer is provided, the sound generated from the diesel engine can be eliminated even if the DPF is disconnected from the exhaust system of the diesel engine.
In the exhaust gas purifying apparatus according to claim 4 of the present invention, the other path where the DPF is not provided among the two paths formed between the two two-way valves is, among the two two-way valves, Since there is a bypass path that communicates with the atmosphere without passing through the two-way valve located downstream of the exhaust gas flow, a diesel engine can be used even if a failure occurs in the two-way valve located downstream of the exhaust gas flow. The passage of the exhaust system can be secured.
The exhaust gas purifying apparatus according to claim 5 of the present invention is provided with pressure detecting means for detecting the exhaust gas pressure on the inlet side of the DPF, and two two-way valves when the pressure detecting means detects a predetermined pressure or more. Are operated so that one path provided with the DPF is closed and exhaust gas discharged from the diesel engine is discharged via the other path not provided with the DPF. The generated DPF can be separated from the exhaust system of the diesel engine.
Since the exhaust gas purifying apparatus according to claim 6 of the present invention is provided with the temperature detecting means for detecting the temperature of the exhaust gas before entering the two-way valve located upstream of the flow of the exhaust gas of the two two-way valves. The exhaust gas temperature of the diesel engine can be detected at any time, and appropriate measures can be taken against the DPF when the exhaust gas temperature is below a predetermined value.

  Hereinafter, an exhaust gas purifying apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an exhaust gas purifying apparatus according to the present invention. In FIG. 1, 1 is a self-regenerating DPF. As this DPF1, a well-known DPF can be used, and a honeycomb-like porous ceramic, or a porous metal filter element disclosed in Japanese Patent Laid-Open No. 4-326912 or Japanese Patent Laid-Open No. Pt), palladium (Pd), rhodium (Rh) or the like may be loaded and loaded into the column, or as shown in JP 2003-214143 A It may be configured to be filled with a filter medium carrying the above-mentioned noble metal. In any case, any self-regenerating DPF that burns and removes carbon fine particles captured by the element by the reaction heat generated by the oxidation reaction of HC and CO in the exhaust gas can be employed. Since this self-regenerating DPF 1 has a structure in which a column is filled with a gas-permeable packing material, it has a function of eliminating sound generated from a diesel engine (not shown) in the same manner as the silencer 2 described later. Also have.

  This self-regenerating DPF 1 has two paths L1 and L2 formed between a pair of two-way valves V1 and V2 having one inlet and two outlets provided in an exhaust system of a diesel engine (not shown). It is detachably provided in one of the paths L1. Of these two two-way valves V1 and V2, the two-way valve V1 is located upstream of the exhaust gas flow of the diesel engine, and the other two-way valve V2 is located downstream thereof. These two two-way valves V1 and V2 are each configured to be driven by an electric valve such as a solenoid valve, and are configured to be operated in synchronization with a drive signal from a controller 3 described later. Has been. In particular, these two two-way valves V1 and V2 are devised so that the opening ratio of the valves can always be maintained at a predetermined value or higher even when switching from the path L1 to L2 or from the path L2 to L1. Therefore, these two valves V1 and V2 do not close the exhaust system of the diesel engine even in the middle of operation, so that the diesel engine is not adversely affected.

  In FIG. 1, reference numeral 2 denotes a silencer (silencer), which is located in the other path L2 of the two paths L1 and L2 formed between the two two-way valves V1 and V2 where the DPF1 is not provided. It is detachable. The silencer 2 is configured in the same manner as a known silencer for eliminating or reducing sound generated from an internal combustion engine such as a diesel engine or a gasoline engine according to the present invention, and is a known type such as a cylindrical type or a shield type. Can be a silencer.

  In FIG. 1, T0, T1, and T2 are temperature sensors for detecting the temperature of the exhaust gas, and the detection signals of these temperature sensors T0, T1, and T2 are input to the controller 3 described later. . Of these temperature sensors T0, T1, and T2, the temperature sensor T0 is upstream of the mounting position of the two-way valve V1 provided upstream of the exhaust gas flow, that is, the inlet side of the two-way valve V1. It is provided at a position where the exhaust gas temperature can be detected. Therefore, the temperature sensor T0 has a feature that the exhaust gas temperature of the diesel engine can always be detected regardless of which direction the two-way valves V1 and V2 are opened and closed.

  The temperature sensor T1 is provided in the path L1 between the two-way valve V1 and the DPF1 positioned upstream of the exhaust gas flow, that is, so as to detect the exhaust gas temperature on the inlet side of the DPF1. Therefore, the temperature sensor T1 has the property of showing the same detected temperature as the temperature sensor T0 when the two-way valves V1 and V2 are opened to the path L1.

  The temperature sensor T2 is provided in the path L1 between the two-way valve V2 and the DPF 1 located on the downstream side of the exhaust gas flow, that is, so as to detect the exhaust gas temperature on the outlet side of the DPF 1. Since this temperature sensor T2 is provided in the same path L1 as the temperature sensor T1, the temperature sensor T2 basically shows the same detected temperature as the temperature sensor T1, but the time difference is as much as the DPF1 intervenes in the middle. And has a characteristic that shows different values by the amount of change (rise) in the DPF1.

  In FIG. 1, P is a pressure sensor provided on the same path position as the temperature sensor T1, that is, on the inlet side of the DPF 1. Therefore, the pressure sensor P can detect the pressure of the exhaust gas on the inlet side of the DPF 1 when the two two-way valves V1 and V2 are open on the path L1 side. The pressure of the exhaust gas corresponds to the back pressure of the diesel engine.

  In FIG. 1, reference numeral 3 denotes a controller mainly composed of a CPU so that the exhaust gas purifying apparatus according to the present invention can be comprehensively controlled. FIG. 2 is a block diagram showing the electrical configuration of the controller 3.

  The controller 3 includes a central processing unit (CPU) 12 that performs arithmetic processing using system program data stored in the ROM 10 and working data stored in the RAM 11. The CPU 12 includes a sensor amplifier 14 for taking in the detection signals of the temperature sensors T0, T1, T2 and the pressure sensor P through the I / O unit 13, and two-way valves V1, V2 comprising motor-operated valves. A valve driver 15 for driving (operating) and a display driver 16 for driving and controlling a display 4 to be described later are connected. The controller 3 includes other components such as a power supply circuit, but is omitted here.

  FIG. 4 shows a driver's cab of a vehicle (not shown) (this vehicle includes a train and a ship equipped with a diesel engine in addition to vehicles such as trucks and buses, and various devices such as construction and civil engineering machines). It is a display connected to the controller 3 provided, the temperature display unit 4a for displaying the exhaust gas temperature of the diesel engine, that is, the temperature of the temperature sensor T0, the state of the DPF 1 and the exhaust gas temperature of the diesel engine. And a lamp group 4b for displaying the state. In the lamp group 4b, the DPF 1 is operating normally, the DPF 1 is abnormal, and the exhaust gas temperature (temperature sensor T0) of the diesel engine is below a predetermined temperature (eg, 200 ° C. or lower). It is configured to be able to display various statuses indicating that it has become. In addition, the indicator 4 can also be provided with a buzzer that notifies the driver of the vehicle by sound when an abnormal state occurs among the various states described above.

  Hereinafter, the control operation of the exhaust gas purification apparatus having the above configuration will be described with reference to the flowchart of FIG. Now, it is assumed that the diesel engine is started prior to driving the vehicle (Yes in Step 100 (Y). Hereinafter, the step is referred to as “S”). When the diesel engine is started, drive power is also supplied to the controller 3 from a power supply circuit (not shown) to enter a drive state. Therefore, detection signals from the temperature sensors T0, T1, T2 and the pressure sensor P are input to the controller 3, respectively.

  Immediately after starting the diesel engine, the exhaust gas temperature of the diesel engine, that is, the temperature of the temperature sensor T0 is equal to or lower than a predetermined temperature required for the DPF 1 to perform self-regeneration, for example, 200 ° C. (hereinafter necessary for the DPF 1 to perform self-regeneration). The minimum temperature is assumed to be 200 ° C.), but this temperature has a property of instantaneously increasing to 200 ° C. or higher when an accelerator pedal (not shown) of the diesel engine is depressed. Therefore, during normal operation of a vehicle equipped with a diesel engine, the temperature sensor T0 does not detect 200 ° C. or lower for several minutes (for example, 1 minute or longer) (No in S102 (N)).

  However, if the vehicle is idling for a long period of time due to a traffic jam or the like, the diesel engine will run at a low speed and the exhaust gas temperature (temperature sensor T0 temperature) will be below 200 ° C. There is. If the exhaust gas temperature is kept at 200 ° C. or lower for a long time, the DPF 1 has a self-regeneration function that is removed by the reaction heat of the catalyst, and the trapped carbon fine particles cause clogging. When the following continues for a predetermined time or longer (for example, when it continues for 1 minute or longer) (S102Y), the two two-way valves V1 and V2 are connected via the valve driver 15 from the path L1 up to that point where the DPF 1 is provided. While switching to the path L2 side where the silencer 2 is provided, the driver is informed through the display 4 that the DPF 1 has stopped the exhaust gas treatment, and is alerted (S103). That is, the ROM 10 (or RAM 11) of the controller 3 switches the two-way valves V1 and V2 from the path L1 to the path L2 when the temperature of the temperature sensor T0 continues for 200 minutes or less for several minutes (for example, 1 minute or more). In addition, since it is programmed to display an alarm on the display 4, the two-way valves V 1 and V 2 are automatically switched and an alarm is issued via the display 4.

  When the two-way valves V1 and V2 are switched to the path L2 side where the silencer 2 is provided, the carbon particulates discharged from the diesel engine are released to the atmosphere without being treated by the DPF 1, but the diesel at this time The engine does not have a significant impact on the environment because of the low-speed rotation and the small amount of carbon particulate emissions. However, since it is not preferable that the carbon fine particles discharged from the diesel engine are released into the atmosphere, the two-way valves V1 and V2 are switched to the path L2 side where the silencer 2 is provided, and via the display 4 If the exhaust gas temperature of the diesel engine (the temperature of the temperature sensor T0) does not recover to 200 ° C. or higher even after a predetermined time (for example, 1 minute) has passed since the alarm was issued, a signal is sent from the controller 3 to the diesel engine control system (not shown). And the diesel engine can be forcibly stopped on condition that the vehicle is stopped.

  As described above, even when the two two-way valves V1 and V2 are controlled to be switched from the path L1 side where the DPF 1 is provided to the path L2 side where the silencer 2 is provided according to the instruction of the controller 3, There may be a failure in which the two-way valve V2 located downstream of the exhaust gas flow does not switch to the path L2 side for some reason. Even when such a failure of the two-way valve V2 occurs, the exhaust gas from the silencer 2 is released to the atmosphere via the bypass path L3, so that the driving of the diesel engine is continued and fail safe is achieved.

  Now, in the steady state where the exhaust gas temperature of the diesel engine (temperature of the temperature sensor T0) exceeds 200 ° C., the heating state of the DPF1 is monitored by the temperature sensors T1 and T2 provided on the inlet side and the outlet side of the DPF1, respectively. At the same time (S104, S106), the clogged state of the DPF 1 is also monitored (No in S106, S107).

  First, from the case where it is determined that the DPF 1 is abnormally heated, the temperature detected by the temperature sensors T1 and T2 provided in the same path L1 is in principle the same temperature, but both temperature sensors T1 and T2 are detected. The temperature sensor T2 is detected with a predetermined time lag (time lag) than the temperature sensor T1, and a temperature higher than the reaction heat of the catalyst in the DPF1 is detected because the DPF1 exists between T2. .

  In the self-regenerating DPF1, it is known that the contact temperature at which the carbon fine particles in the exhaust gas from the diesel engine can be satisfactorily oxidized and removed is 250 to 500 ° C, preferably around 350 ° C. The temperature difference between the temperature side and the outlet side, that is, the temperature difference between the temperature sensors T1 and T2 (T2−T1 when the temperatures of the sensors T1 and T2 are T1 and T2) is also known. When exceeding, it can be determined that there is abnormal combustion in the DPF 1, that is, a fire condition. Therefore, the controller 3 determines that the DPF 1 is in an abnormal heating state when the temperature difference between the temperature sensors T1 and T2 exceeds the temperature difference (threshold value) stored in the ROM 10 (or RAM 11) in advance. The two two-way valves V1 and V2 are switched from the path L1 side where the DPF1 is provided to the path L2 side where the silencer 2 is provided, and the display 4 is notified that an abnormality has occurred in the DPF1 ( S106 affirmative, S108). In this way, the DPF 1 in which an abnormality has occurred can be separated from the exhaust system of the diesel engine. When an abnormality occurs in the DPF 1, the driver moves the vehicle to a predetermined location such as a maintenance factory and performs a recovery process (110).

  The above description is for when abnormal heating occurs in the DPF 1. However, when the temperature difference between the temperature sensors T1 and T2 is less than a predetermined temperature even when the time lag is taken into account, the temperature of the temperature sensor T1 is If the temperature is higher than the temperature sensor T2, it is possible that the catalyst reaction of the DPF 1 is abnormal or that the temperature sensor T1 or T2 has failed. , V2 may be switched to the path L2 where the silencer 2 is provided to display an alarm on the display 4.

  Even if the temperature difference between the temperature sensors T1 and T2 is within the temperature difference where the DPF 1 functions well, it is possible that the DPF 1 is clogged for some reason. If this clogging is left as it is, the clogged carbon fine particles are ignited and cause abnormal heating. Therefore, when the pressure sensor P exceeds a predetermined pressure (No in S106, S107 positive), the two-way valve V1. , V2 are switched from the path L1 side where the DPF 1 is provided to the path L2 side where the silencer 2 is provided, and the display unit 4 is notified of the occurrence of clogging in the DPF 1 (S108). That is, since the pressure value on the inlet side of the DPF 1 when the DPF 1 is clogged in advance is stored in the ROM 10 (or RAM 11) of the controller 3, the pressure of the pressure sensor P is the stored pressure value. The controller 3 switches the two-way valves V1 and V2 to the path L2 side and controls so that an alarm is issued via the display 4. Therefore, when such an abnormality occurs, the driver moves the vehicle to a predetermined place such as a maintenance factory and performs the restoration process of the DPF 1 (S110).

  In the above example, the silencer 2 is provided in the path L2, but this can be omitted. However, if this silencer 2 is provided, the noise when the diesel engine is continuously operated by switching from the route L1 provided with the DPF 1 to the route L2 can be reduced or eliminated, and it has been installed in the past. There is an effect that can be used without removing the silencer.

1 is a schematic configuration diagram of an exhaust gas purifying apparatus according to an embodiment of the present invention. It is a block diagram which shows schematic structure of a controller. It is a flowchart which shows control operation.

Explanation of symbols

1 DPF
2 Silencer 3 Controller 4 Display L1, L2 path L3 Bypass path V1, V2 Two-way valve T0, T1, T2 Temperature sensor P Pressure sensor 10 ROM
11 RAM
12 CPU
13 I / O unit 14 Sensor amplifier 15 Valve driver 16 Display driver

Claims (6)

An exhaust gas purifying apparatus equipped with a self-regenerating diesel particulate filter that collects carbon particulates contained in exhaust gas discharged from a diesel engine and burns and removes the collected carbon particulates by reaction heat of the catalyst. In
Temperature detecting means for detecting exhaust gas temperature on the inlet side and exhaust gas temperature on the outlet side of the diesel particulate filter, and
Monitoring means for monitoring the heating state of the diesel particulate filter based on the difference between the detected exhaust gas temperature on the inlet side and the exhaust gas temperature on the outlet side of the detected diesel particulate filter;
An exhaust gas purification apparatus comprising:   The exhaust gas purification apparatus according to claim 1, wherein the diesel particulate filter is provided in one of two paths formed between two two-way valves, and the diesel particulate filter is provided by a monitoring unit. When it is determined to be in a predetermined heating state, each of the two two-way valves is operated to close one of the paths where the diesel particulate filter is provided and discharged from the diesel engine. An exhaust gas purifying apparatus, characterized in that exhaust gas is discharged through the other route not provided with the diesel particulate filter.   The exhaust gas purifying apparatus according to claim 2, wherein a sound generated from a diesel engine is generated in the other path where the diesel particulate filter is not provided, out of the two paths formed between the two two-way valves. An exhaust gas purifier having a silencer for disappearance.   The exhaust gas purifying apparatus according to claim 2 or 3, wherein the two two-way valves are provided in the other route not provided with the diesel particulate filter among the two routes formed between the two two-way valves. Among these, an exhaust gas purifying apparatus characterized in that a bypass path communicating with the atmosphere is provided without passing through a two-way valve located downstream of the exhaust gas flow.   The exhaust gas purification apparatus according to any one of claims 2 to 4, wherein a pressure detection means for detecting the exhaust gas pressure on the inlet side of the diesel particulate filter is provided, and the pressure detection means detects a pressure higher than a predetermined value. In addition, each of the two two-way valves is operated to close one path where the diesel particulate filter is provided, and the exhaust gas discharged from the diesel engine is sent to the other side where the diesel particulate filter is not provided. An exhaust gas purifying apparatus characterized by being discharged through a route.   6. The exhaust gas purifying apparatus according to claim 2, wherein the temperature detection means detects the temperature of the exhaust gas before entering the two-way valve located upstream of the flow of the exhaust gas of the two two-way valves. An exhaust gas purification device characterized by comprising:

Images