JP4447510B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine, particularly an internal combustion engine for purifying exhaust gas by collecting particulates in exhaust gas discharged from a diesel engine with a filter.

  In general, in a diesel engine (hereinafter referred to as “engine”) using this type of exhaust gas purification device, if the amount of particulate (hereinafter referred to as “PM”) accumulated on the filter increases, This will lead to a decrease in fuel consumption. An exhaust gas purification device that regenerates a filter in order to avoid such a problem has been conventionally known. For example, Patent Document 1 discloses the exhaust gas purification device.

  In this exhaust gas purifying apparatus, the amount of PM deposited on the filter is estimated, and the filter is regenerated when the estimated amount of PM deposited becomes larger than a predetermined threshold value. Specifically, in addition to the fuel required for engine combustion, unburned fuel is included in the exhaust gas by post injection that injects fuel into the combustion chamber during the exhaust stroke, and this unburned fuel is filtered from the filter in the exhaust pipe. Also, the PM is accumulated on the filter by burning it upstream and forcibly raising the exhaust gas temperature to regenerate the filter.

  However, this conventional exhaust gas purification device has the following problems. That is, as described above, since the filter is regenerated by post-injection in which fuel is injected into the combustion chamber during the exhaust stroke, a part of the post-injected fuel is not discharged from the combustion chamber, and the wall surface of the cylinder Oil dilution occurs as a result of adhering to the oil and mixing in the lubricating oil of the engine. Further, since the fuel that has been post-injected does not contribute to the combustion of the engine, the fuel efficiency is deteriorated accordingly.

  The present invention has been made in order to solve the above-described problems, and is capable of appropriately regenerating a filter, and can achieve suppression of oil dilution and improvement of fuel consumption, and an exhaust gas purification device for an internal combustion engine. The purpose is to provide.

JP 2001-280118 A

  In order to achieve the above object, the invention according to claim 1 is an exhaust gas purification apparatus 1 for an internal combustion engine that purifies exhaust gas by collecting particulates in the exhaust gas discharged from the internal combustion engine 3. The filter 18 is provided in the system (the exhaust pipe 5 in the embodiment (hereinafter the same in this section)) and collects particulates in the exhaust gas, and the filter 18 by the first regeneration mode for supplying unburned fuel into the exhaust gas. First regeneration means (injector 6, ECU 2, step 11), and second regeneration means (supercharger 7, 7) for regenerating the filter 18 in a second regeneration mode that does not depend on the supply of unburned fuel into the exhaust gas. Throttle valve 12, actuator 12 a, glow plug 16, ECU 2, step 18), internal combustion engine load (engine speed NE, target fuel injection) QINJ) is selected as a load detection means (crank angle sensor 30, accelerator opening sensor 34, ECU 2, step 21), and the first regeneration mode is selected when the detected load is in a predetermined first load region, Regeneration mode selection means (ECU 2, steps 2 to 4 and 6) for selecting the second regeneration mode when in a predetermined second load region other than the first load region, and the amount of particulates collected by the filter 18 Particulate amount detection means (crank angle sensor 30, exhaust gas temperature sensor 33, ECU 2, step 1) for detecting (PM accumulation amount DPFPMS) and when the detected particulate amount is larger than a predetermined threshold value PMREF The reproduction execution means (EC) that causes one of the first and second reproduction means to reproduce the filter 18 in accordance with the selected reproduction mode. 2, step 9, 10, 16, 17) and the threshold value setting means for setting the predetermined threshold value PMREF to a smaller value when the load is in the second load region than when the load is in the first load region. (ECU2, steps 8, 14).

  According to the exhaust gas purification apparatus for an internal combustion engine, as a regeneration mode for regenerating the filter, a first regeneration mode in which unburned fuel is supplied into the exhaust gas, and a second regeneration mode that does not depend on the supply of unburned fuel into the exhaust gas. Is set, reproduction in the first reproduction mode is performed by the first reproduction means, and reproduction in the second reproduction mode is performed by the second reproduction means. The first regeneration mode is selected when the load detected by the regeneration mode selection means is in a predetermined first load region, and the second regeneration mode is selected when the load is in a predetermined second load region other than the first load region. Selected. Further, when the detected particulate amount is larger than a predetermined threshold value by the regeneration executing means, the first or second regeneration means is caused to regenerate the filter according to the selected regeneration mode. As a result, when regeneration in the first regeneration mode is executed, unburned fuel is supplied into the exhaust gas. As a result, the fuel is burned on the filter or upstream side thereof, and the temperature of the filter is increased, thereby increasing the filter temperature. The particulates deposited on the surface burn and the filter is regenerated. Further, when regeneration in the second regeneration mode is executed, the filter is regenerated without supplying unburned fuel into the exhaust gas. As described above, the filter can be appropriately regenerated by performing the regeneration in the first or second regeneration mode according to the load of the internal combustion engine.

  Further, by the setting by the threshold setting means, the predetermined threshold value is set to a smaller value when the load is in the second load region than when it is in the first load region. By setting such a threshold value, regeneration in the second regeneration mode is executed early from a state where the amount of particulates in the filter is relatively small, and by increasing the execution frequency, the filter is used in the second load region. The amount of collected particulates is kept low. As a result, since the threshold value is set to a larger value in the first load region, the particulate amount is less likely to exceed the threshold value in the first load region. As a result, regeneration in the first regeneration mode is executed. And the execution frequency is reduced. Thus, since the frequency of regeneration in the first regeneration mode for supplying unburned fuel into exhaust gas can be reduced, fuel efficiency can be improved, and supply of unburned fuel in exhaust gas can be performed during an expansion stroke, etc. In addition, when the fuel is supplied to the combustion chamber, oil dilution can be suppressed.

  The invention according to claim 2 is the exhaust gas purification apparatus 1 for an internal combustion engine according to claim 1, wherein the second load region is a region where the load is larger than the first load region (FIG. 5). .

  According to this configuration, regeneration in the second regeneration mode is executed when the detected load is in the second load region where the load is greater. When the load on the internal combustion engine is high, the exhaust gas temperature is high, so the filter temperature is high, so there is no need to raise the filter temperature so much for regeneration, so unburned fuel is supplied into the exhaust gas The filter can be properly reproduced also by the reproduction in the second reproduction mode that is not performed.

  Further, when the load is in the first load region and the load on the internal combustion engine is low, regeneration in the first regeneration mode is executed. When the load is low in this way, the exhaust gas temperature is low and the filter temperature is low, so it is necessary to greatly increase the filter temperature for regeneration. In the present invention, when the load on the internal combustion engine is low, unburned fuel is supplied into the exhaust gas by regeneration in the first regeneration mode, so that the filter can be properly regenerated by sufficiently raising the temperature of the filter. Can be done.

  According to a third aspect of the present invention, in the exhaust gas purification apparatus 1 for an internal combustion engine according to the second aspect, the internal combustion engine 3 is mounted on the vehicle V as a drive source, and a vehicle speed detecting means for detecting the vehicle speed VP ( A vehicle speed sensor 35), and the threshold value setting means sets the predetermined threshold value PMREF so that the load is in the second load region and the detected vehicle speed is higher than the predetermined speed (predetermined value VPREF). It carries out when it is high (steps 13 and 14).

  According to this configuration, in addition to the load being in the second load region, on the condition that the detected vehicle speed is higher than the predetermined speed, that is, when the load of the internal combustion engine is high and the vehicle speed is high, The threshold value is set to a smaller value than when the threshold value is in the first load region. For example, even if the load suddenly increases due to the acceleration operation in a low load state, and the transition from the first load region to the second load region, the temperature of the filter does not rise immediately but may be in a low state. In this case, there is a possibility that the filter cannot be properly reproduced even if the reproduction is performed in the second reproduction mode. With the above-described configuration, even when the load on the internal combustion engine is high, setting of a small threshold by the threshold setting means is prohibited when there is a possibility that the filter is cold due to low vehicle speed. By setting to a larger value, it is possible to reduce the frequency of playback in the second playback mode, thereby suppressing the occurrence of the above problems.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an exhaust gas purification device 1 according to the present invention and an internal combustion engine 3 to which the exhaust gas purification device 1 is applied. This internal combustion engine (hereinafter referred to as “engine”) 3 is, for example, a four-cylinder type diesel engine mounted on a vehicle V.

  A combustion chamber 3c is formed between the piston 3a of the engine 3 and the cylinder head 3b. An intake pipe 4 and an exhaust pipe 5 (exhaust system) are connected to the cylinder head 3b, respectively, and a fuel injection valve (hereinafter referred to as “injector”) 6 (first regeneration means) and a glow plug 16 (second regeneration means). Is attached so as to face the combustion chamber 3c.

  The injector 6 is disposed at the central portion of the top wall of the combustion chamber 3c, and is sequentially connected to a high-pressure pump 6a and a fuel tank (not shown) via a common rail (not shown). The high-pressure pump 6a boosts the fuel in the fuel tank to a high pressure and then sends it to the injector 6 through the common rail. The injector 6 injects this fuel into the combustion chamber 3c. The fuel injection pressure PRAIL is controlled by controlling the high pressure pump 6a with the ECU 2 described later (see FIG. 2), and is detected by the fuel pressure sensor 36 provided on the common rail, and the detection signal is output to the ECU 2. The In addition, the valve opening time and the on-off valve timing of the injector 6 are controlled by a drive signal from the ECU 2, thereby controlling the fuel injection amount and the injection timing, respectively. The glow plug 16 is for increasing the temperature of the combustion chamber 3c, and is controlled by controlling the energization amount by the ECU 2.

  A magnet rotor 30a is attached to the crankshaft 3d of the engine 3, and a crank angle sensor 30 (load detection means, particulate quantity detection means) is configured by the magnet rotor 30a and the MRE pickup 30b. The crank angle sensor 30 outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 2 as the crankshaft 3d rotates.

  The CRK signal is output every predetermined crank angle (for example, 30 °). The ECU 2 obtains the rotational speed NE (hereinafter referred to as “engine rotational speed”) NE of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that the piston 3a of each cylinder is at a predetermined crank angle position near the TDC (top dead center) at the start of the intake stroke, and in this example of the 4-cylinder type, every crank angle of 180 °. Is output.

  The intake pipe 4 is provided with a supercharging device 7 (second regeneration means). The supercharging device 7 includes a supercharger 8 composed of a turbocharger, an actuator 9 connected thereto, and a vane. An opening control valve 10 is provided.

  The supercharger 8 includes a rotatable compressor blade 8a provided in the intake pipe 4, a rotatable turbine blade 8b provided in the exhaust pipe 5, and a plurality of rotatable variable vanes 8c (only two are shown). And a shaft 8d for integrally connecting these blades 8a and 8b. The turbocharger 8 pressurizes the intake air in the intake pipe 4 by rotationally driving the compressor blade 8a integrated therewith as the turbine blade 8b is rotationally driven by the exhaust gas in the exhaust pipe 5. Perform supercharging operation.

  The actuator 9 is of a diaphragm type that is operated by negative pressure, and is mechanically connected to each variable vane 8c. A negative pressure is supplied to the actuator 9 from a negative pressure pump through a negative pressure supply passage (both not shown), and a vane opening degree control valve 10 is provided in the middle of the negative pressure supply passage. The vane opening control valve 10 is composed of an electromagnetic valve, and the negative pressure supplied to the actuator 9 changes when the opening is controlled by a drive signal from the ECU 2, and accordingly, the variable vane 8c The supercharging pressure is controlled by changing the opening degree.

  A water-cooled intercooler 11 and a throttle valve 12 (second regeneration means) are provided downstream from the supercharger 8 of the intake pipe 4 in order from the upstream side. The intercooler 11 cools the intake air when the temperature of the intake air rises due to the supercharging operation of the supercharging device 7 or the like. The throttle valve 12 is connected to an actuator 12a (second regeneration means) made of, for example, a DC motor. The opening degree of the throttle valve 12 (hereinafter referred to as “throttle valve opening degree”) is controlled by controlling the duty ratio of the current supplied to the actuator 12 a by the ECU 2.

  The intake pipe 4 is provided with an air flow sensor 31 upstream of the supercharger 8 and a supercharging pressure sensor 32 between the intercooler 11 and the throttle valve 12. The air flow sensor 31 detects the intake air amount QA, the supercharging pressure sensor 32 detects the supercharging pressure PACT in the intake pipe 4, and these detection signals are output to the ECU 2.

  Further, the intake manifold 4a of the intake pipe 4 is partitioned into a swirl passage 4b and a bypass passage 4c from the collecting portion to the branch portion, and each of the passages 4b and 4c is connected to each combustion chamber 3c via an intake port. Communicating with A swirl device 13 is provided in the bypass passage 4c. The swirl device 13 includes a swirl valve 13a, an actuator 13b for opening and closing the swirl valve 13a, and a swirl control valve 13c. By controlling the opening degree of the swirl control valve 13c by the ECU 2, the strength of the swirl generated in the combustion chamber 3c is controlled by changing the opening degree of the swirl valve 13a.

  The engine 3 is provided with an EGR device 14 having an EGR pipe 14a and an EGR control valve 14b. The EGR pipe 14 a is connected between the intake pipe 4 and the exhaust pipe 5, specifically, so as to connect the swirl passage 4 b of the collecting portion of the intake manifold 4 a and the upstream side of the supercharger 8 of the exhaust pipe 5. Has been. Through this EGR pipe 14a, a part of the exhaust gas of the engine 3 is recirculated to the intake pipe 4 as EGR gas, thereby reducing the combustion temperature in the combustion chamber 3c, thereby reducing NOx in the exhaust gas. .

  The EGR control valve 14b is configured by a linear electromagnetic valve attached to the EGR pipe 14a, and the EGR gas amount is controlled by controlling the valve lift amount linearly by a drive signal from the ECU 2.

  Further, the EGR device 14 is provided with an EGR cooling device 15 for cooling EGR gas, and the EGR cooling device 15 is located downstream of the EGR passage switching valve 15b and the EGR control valve 14b of the EGR pipe 14a. The EGR cooler 15c is provided. A bypass passage 15a is provided downstream of the EGR pipe 14a from the EGR control valve 14b so as to bypass the EGR cooler 15c, and the EGR passage switching valve 15b is attached to a branch portion of the bypass passage 15a. The EGR passage switching valve 15b selectively switches a portion of the EGR pipe 14a on the downstream side of the EGR passage switching valve 15b to the EGR cooler 15c side and the bypass passage 15a side under the control of the ECU 2.

  As described above, when the EGR passage switching valve 15b is switched to the bypass passage 15a side, the EGR gas passes through the bypass passage 15a and returns to the intake pipe 4. On the other hand, when switched to the reverse side, the EGR gas is cooled by the EGR cooler 15c and then returned to the intake pipe 4.

  Further, an oxidation catalyst 17 and a filter 18 are provided on the exhaust pipe 5 downstream of the supercharger 8 in order from the upstream side. The oxidation catalyst 17 oxidizes HC and CO in the exhaust gas and purifies the exhaust gas. The filter 18 collects particulates such as soot in the exhaust gas (hereinafter referred to as “PM”), thereby reducing PM discharged into the atmosphere. The filter 18 carries a catalyst (not shown) similar to the oxidation catalyst 17 on its surface.

  Further, an exhaust gas temperature sensor 33 (particulate amount detection means) is provided immediately upstream of the filter 18 in the exhaust pipe 5. The exhaust gas temperature sensor 33 detects the temperature of the exhaust gas immediately upstream of the filter 18 (hereinafter referred to as “pre-filter gas temperature”) TDPFG, and outputs a detection signal to the ECU 2.

  The ECU 2 further receives an operation amount (hereinafter referred to as “accelerator opening”) AP and vehicle speed VP of an accelerator pedal (not shown) from an accelerator opening sensor 34 (load detection means) and a vehicle speed sensor 35 (vehicle speed detection means). Representing detection signals are respectively output.

  The ECU 2 is composed of a microcomputer including an I / O interface, CPU, RAM, ROM, and the like. The detection signals from the various sensors 30 to 36 described above are each input to the CPU after A / D conversion and shaping by the I / O interface.

  In accordance with these input signals, the CPU determines the operating state of the engine 3 according to a control program stored in the ROM, etc., and executes a regeneration control process for regenerating the filter 18 according to the determined operating state. To do. In the present embodiment, the ECU 2 constitutes a first regeneration means, a second regeneration means, a load detection means, a regeneration mode selection means, a particulate quantity detection means, a regeneration execution means, and a threshold setting means. .

  Next, the reproduction control process will be described with reference to FIG. This process is executed in synchronization with the input of the TDC signal. First, in step 1 (illustrated as “S1”, the same applies hereinafter), a DPFPMS of PM deposited on the filter 18 (hereinafter referred to as “PM deposition amount”) is calculated.

  Specifically, the PM emission amount discharged from the engine 3 is calculated by searching a PM emission amount map (not shown) according to the engine speed NE and the target fuel injection amount QINJ. Next, the amount of PM burned by the filter 18 is calculated by searching a table (not shown) based on the pre-filter gas temperature TDPFG. Then, by subtracting the PM combustion amount from the obtained PM emission amount, the PM deposition amount per 1 TDC is calculated, and this PM deposition amount per 1 TDC is added to the previous value of the PM deposition amount DPFPMS. The PM deposition amount DPFPMS is calculated.

  The PM emission amount map is obtained by experimentally determining the amount of PM discharged from the engine 3 and mapping the result according to the engine speed NE and the target fuel injection amount QINJ. The target fuel injection amount QINJ is a target value of the fuel injection amount, and is calculated by searching a map (not shown) according to the engine speed NE and the accelerator pedal opening AP in step 21 of FIG. Further, the fuel injection amount is controlled by outputting a drive signal based on the target fuel injection amount QINJ to the injector 6. The PM combustion amount is calculated to be larger as the pre-filter gas temperature TDPFG is higher.

  Next, it is determined whether or not the load of the engine 3 is in a predetermined first load region (step 2). This determination is performed based on the region map shown in FIG. 5 according to the engine speed NE and the target fuel injection amount QINJ. In this region map, the first load region is set to a region where the engine speed NE is low to high and the target fuel injection amount QINJ is low to medium, that is, a low to medium load region.

  When the answer to step 2 is YES, the load is in the first load region, and the engine 3 is in the low to medium load operation state, the first regeneration mode is selected as the regeneration mode of the filter 18 to express that fact. Then, the first reproduction mode flag F_RE1 is set to “1” (step 3).

  On the other hand, when the answer to step 2 is NO, it is determined whether or not the load of the engine 3 is in the second load region (step 4). This determination is performed based on the region map in accordance with the engine speed NE and the target fuel injection amount QINJ, as in step 2 above. In this region map, the second load region is set to a region where the engine speed NE is low to high and the target fuel injection amount QINJ is high, that is, a high load region.

  If the answer to step 4 is YES, the load is in the second load region, and the engine 3 is in the high load operation state, the second regeneration mode is selected and the first regeneration mode flag F_RE1 is set to “0”. (Step 6).

  On the other hand, when the answer to step 4 is NO, that is, when the load of the engine 3 is not in any of the first and second load regions, it is determined that the engine 3 is not in an operation state suitable for the regeneration control. This processing is terminated.

  When Step 3 is executed, that is, when the first reproduction mode is selected, Steps 7 to 11 are executed. First, in step 7, it is determined whether or not the execution flag F_RE1ON for the first reproduction mode is “1”. If the answer is NO and regeneration in the first regeneration mode is not being executed, the threshold value PMREF is set to a predetermined first threshold value PMREF1 (for example, 9 g) (step 8). Next, it is determined whether or not the PM deposition amount DPFPMS calculated in Step 1 is larger than a set threshold value PMREF (Step 9). When this answer is NO, it is assumed that the regeneration control is not executed, and this process is terminated.

  On the other hand, if the answer to step 9 is YES and the PM accumulation amount DPFPMS is larger than the threshold value PMREF, the in-execution flag F_RE1ON is set to “1”, assuming that regeneration in the first regeneration mode is started ( Simultaneously with step 10), the reproduction control in the first reproduction mode is executed (step 11), and this process is terminated.

  In the regeneration control in the first regeneration mode, the pre-filter gas temperature TDPFG is set to a target temperature (for example, 600 ° C.) by controlling the amount of fuel by post injection for injecting fuel into the combustion chamber 3c during the expansion stroke or the exhaust stroke. ) To control the filter 18 to a high temperature state. Thereby, the filter 18 can be appropriately regenerated by burning the PM deposited on the filter 18.

  Specifically, when the pre-filter gas temperature TDPFG <target temperature, the pre-filter gas temperature TDPFG is increased by increasing the amount of unburnt fuel contained in the exhaust gas by increasing the amount of fuel by post injection. . In addition to the post injection control, the throttle valve opening and the boost pressure PACT are decreased and the energization amount of the glow plug 16 is increased. By the above control, the pre-filter gas temperature TDPFG is raised by raising the combustion temperature and raising the temperature of the exhaust gas. On the other hand, when TDPFG> target temperature, the pre-filter gas temperature TDPFG is lowered by the reverse operation to the above. Control other than the above-described post-injection control, such as throttle valve opening, is hereinafter collectively referred to as “regeneration engine control”.

  Note that the regeneration control in the first regeneration mode starts, and when the PM accumulation amount DPFPMS calculated as described above becomes smaller than the determination value, the PM deposited on the filter 18 is sufficiently burned, The playback is terminated as appropriate. This determination value is set to a small predetermined value close to the value 0.

  On the other hand, when step 6 is executed, that is, when the second reproduction mode is selected, steps 12 to 18 are executed. First, in step 12, it is determined whether or not the execution flag F_RE2ON for the second reproduction mode is “1”. If the answer is NO and regeneration in the second regeneration mode is not being executed, it is determined whether or not the vehicle speed VP is greater than a predetermined value VPREF (for example, 130 km / h) (step 13). When the answer is YES, that is, when the high load high speed operation is being performed, the threshold value PMREF is set to a predetermined second threshold value PMREF2 (step 14), and the process proceeds to step 16. The second threshold value PMREF2 is set to a value smaller than the first threshold value PMREF1 used in Step 8, and is 6 g, for example.

  On the other hand, if the answer to step 13 is NO and VP ≦ VPREF, the threshold value PMREF is set to the first threshold value PMREF1 (step 15), and the process proceeds to step 16. In this step 16, it is determined whether or not the PM accumulation amount DPFPMS is larger than the set threshold value PMREF. When this answer is NO, it is assumed that the regeneration control is not executed, and this process is terminated.

  On the other hand, if the answer to step 16 is YES and the PM accumulation amount DPFPMS is greater than the threshold value PMREF, the in-execution flag F_RE2ON is set to “1”, assuming that regeneration in the second regeneration mode is started. Along with (Step 17), reproduction control in the second reproduction mode is executed (Step 18), and this process is terminated. In this regeneration control, unlike the regeneration control in the first regeneration mode in step 11, the post-injection is not performed, so that only the regeneration engine control is performed without supplying unburned fuel in the exhaust gas. Thereby, the filter 18 can be appropriately regenerated by controlling the pre-filter gas temperature TDPFG to be the target temperature.

  Note that after the start of the regeneration control in the second regeneration mode, as in the case of the first regeneration mode, when the PM deposition amount DPFPMS becomes smaller than the determination value, the regeneration control is terminated. The

  As described above, according to the present embodiment, the first regeneration mode is selected when the load of the engine 3 is in the first load region, and the second regeneration mode is selected when the load is in the second load region. When the accumulation amount DPFPMS becomes larger than the threshold value PMREF, regeneration control according to the selected regeneration mode is executed. The threshold value PMREF is set to a smaller second threshold value PMREF2 when the load of the engine 3 is in the second load region, and is set to a larger first threshold value PMREF1 when the load is in the first load region. To do. As a result, the frequency of execution of regeneration control in the first regeneration mode in which unburned fuel is supplied into the exhaust gas can be reduced, so that oil dilution can be suppressed and fuel consumption can be improved.

  Furthermore, since the regeneration control in the second regeneration mode in which unburned fuel is not supplied into the exhaust gas is executed when the engine 3 is in a high load operation state, the filter 18 can be properly regenerated. In addition, when the engine 3 is in a low to medium load operation state, regeneration control is executed in the first regeneration mode in which unburned fuel is supplied into the exhaust gas, so regeneration can be performed appropriately.

  Further, even when the load is in the second load region, when the vehicle speed VP is smaller than the predetermined value VPREF, the threshold value PMREF is set to a larger first threshold value PMREF1, so that the filter 18 may be at a low temperature. When there is, it is possible to reduce the frequency of execution of the regeneration control in the second regeneration mode, thereby suppressing the regeneration of the filter 18 from being performed inappropriately.

  In addition, this invention can be implemented in various aspects, without being limited to the described embodiment. For example, in the embodiment, the unburned fuel is supplied into the exhaust gas in the first regeneration mode by post injection to the combustion chamber 3c using the injector 6, but upstream of the filter 18 in the exhaust pipe 5. A separate injector may be provided on the side so that the fuel is directly injected into the exhaust pipe 5. In the embodiment, the regeneration control in the second regeneration mode is performed by the above-described regeneration engine control. However, the type and combination of control parameters such as the throttle valve opening constituting the regeneration engine control are arbitrary. It is. Further, other appropriate control may be performed as long as the temperature of the filter 18 can be controlled without supplying unburned fuel in the exhaust gas. For example, the heating control of the filter 18 by a heater may be performed. .

  Further, in the embodiment, the calculation of the PM accumulation amount DPFPMS is performed by subtracting the PM combustion amount calculated based on the pre-filter gas temperature TDPFG from the PM emission amount calculated based on the operating state of the engine 3. However, it may be performed by detecting any differential pressure between the upstream side and the downstream side of the filter 18 and calculating the differential pressure and the exhaust gas flow rate. Further, the PM deposition amount calculated in this way may be compared with the PM deposition amount DPFPMS of the embodiment, and the larger one may be used as the PM deposition amount DPFPMS. Furthermore, although embodiment is an example which applied this invention to the diesel engine, this invention is not limited to this, Various engines other than a diesel engine, for example, the ship which arrange | positioned the gasoline engine and the crankshaft in the perpendicular direction It can be applied to an engine for a marine propulsion device such as an external unit. In addition, it is possible to appropriately change the detailed configuration within the scope of the present invention.

1 is a diagram schematically illustrating an exhaust gas purification apparatus according to an embodiment and an internal combustion engine to which the exhaust gas purification apparatus is applied. It is a figure which shows roughly a part of exhaust gas purification apparatus by this embodiment. It is a flowchart which shows a reproduction | regeneration control process. It is a flowchart which shows the target fuel injection amount QINJ calculation process. It is an example of the area | region map used by the process of FIG.

Explanation of symbols

1 Exhaust gas purification device
2 ECU (first regeneration means, second regeneration means, load detection means, regeneration mode selection
Means, particulate quantity detection means, regeneration execution means, threshold value
Setting method)
3 Engine
5 Exhaust pipe (exhaust system)
6 Injector (first regeneration means)
7 Supercharging device (second regeneration means)
12 Throttle valve (second regeneration means)
12a Actuator (second regeneration means)
16 Glow plug (second regeneration means)
18 Filter
30 Crank angle sensor (load detection means, particulate quantity detection means)
33 Exhaust gas temperature sensor (particulate amount detection means)
34 Accelerator opening sensor (load detection means)
35 Vehicle speed sensor (vehicle speed detection means)
V Vehicle NE Engine speed (load of internal combustion engine)
QINJ Target fuel injection amount (load of internal combustion engine)
DPFPMS PM deposition amount (particulate amount collected by the filter)
PMREF threshold VPREF Predetermined value (predetermined speed)

Claims (3)

An exhaust gas purification device for an internal combustion engine that purifies exhaust gas by collecting particulates in the exhaust gas discharged from the internal combustion engine,
A filter provided in the exhaust system for collecting particulates in the exhaust gas;
First regeneration means for regenerating the filter in a first regeneration mode for supplying unburned fuel into the exhaust gas;
Second regeneration means for regenerating the filter in a second regeneration mode that does not depend on the supply of unburned fuel into the exhaust gas;
Load detecting means for detecting a load of the internal combustion engine;
The first regeneration mode is selected when the detected load is in a predetermined first load region, and the second regeneration mode is selected when the detected load is in a predetermined second load region other than the first load region. Playback mode selection means;
Particulate amount detection means for detecting the amount of particulates collected in the filter;
Regeneration executing means for causing one of the first and second regeneration means to perform regeneration of the filter according to the selected regeneration mode when the detected particulate amount is greater than a predetermined threshold;
Threshold setting means for setting the predetermined threshold value to a smaller value when the load is in the second load region than when the load is in the first load region;
An exhaust gas purifying device for an internal combustion engine, comprising:   2. The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the second load region is a region where the load is larger than that of the first load region. The internal combustion engine is mounted on a vehicle as a drive source,
Vehicle speed detecting means for detecting the speed of the vehicle,
The threshold setting means performs the setting of the predetermined threshold when the load is in the second load region and the detected vehicle speed is higher than a predetermined speed. The exhaust gas purification apparatus for an internal combustion engine according to claim 2.

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