JP2006316732A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device of an internal combustion engine capable of improving fuel economy, and capable of preventing melting damage of a filter, by properly performing regeneration operation, in response to the actual temperature of the filter. <P>SOLUTION: This exhaust emission control device 1 has the filter 8 arranged in an exhaust system 5 and collecting a particulate in exhaust gas, a catalyst 7 arranged on the upstream side of the filter 8 of the exhaust system 5 and oxidizing the exhaust gas, and a regenerating means 6 for regenerating the filter 8 by supplying unburnt fuel in the exhaust gas on the upstream side of the catalyst 7; and calculates the raised temperature TUDPF of the filter raised by burning the unburnt fuel in the filter 8 in the regeneration operation of the regenerating means 6 (Step 6); and controls the regeneration operation of the regenerating means in response to the detected exhaust gas temperature TDPF between the catalyst 7 and the filter 8 and the calculated raised temperature TUDPF of the filter (Step 7 to 9A, and 13 to 16). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification apparatus for an internal combustion engine that purifies exhaust gas by collecting particulates in the exhaust gas discharged from the internal combustion engine.

  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 purification device, 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. Further, a temperature sensor is directly attached to the filter, and the amount of fuel injected by the post injection (hereinafter referred to as “post injection amount”) is determined by the temperature of the filter detected by the temperature sensor being a predetermined target temperature. Is set to be This target temperature is set to a temperature at which the filter can be regenerated and the filter does not melt.

  As described above, in the conventional exhaust gas purification apparatus, the temperature sensor that detects the temperature of the filter is directly attached to the filter. For this reason, for example, when the element of the temperature sensor is arranged in the casing of the filter, the temperature detected by the temperature sensor tends to shift to a lower temperature side than the actual temperature of the filter due to the influence of outside air or the like. Further, in this exhaust gas purifying apparatus, the post injection amount is set so that the detected temperature becomes a predetermined target temperature. Therefore, if the detected temperature shifts to a low temperature side, the post injection amount is excessively set accordingly, and the fuel consumption is reduced. Will get worse. In addition, the filter may melt due to the actual temperature of the filter exceeding the target temperature and the filter becoming overheated.

  Or in order to detect the temperature of a filter appropriately, when the element of a temperature sensor is arrange | positioned inside the filter, it is necessary to make a hole in the filter. In that case, the amount of PM that can be deposited decreases, the flow of exhaust gas becomes non-uniform, and the accumulated state of PM varies, so that the desired performance of the filter cannot be obtained.

  The present invention has been made to solve the above-described problems, and according to the actual temperature of the filter, it is possible to appropriately perform the regeneration operation of the filter, thereby improving fuel consumption, An object of the present invention is to provide an exhaust gas purification device for an internal combustion engine that can prevent the filter from being melted.

JP 2003-35131 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. System (exhaust pipe 5 in the embodiment (hereinafter the same in this section)), a filter 8 for collecting particulates in the exhaust gas, and an upstream side of the exhaust system filter 8 to oxidize the exhaust gas Catalyst (oxidation catalyst 7), regeneration means (injector 6, ECU 2) for regenerating the filter by supplying unburned fuel into the exhaust gas upstream of the catalyst, and unburned during regeneration operation of the regeneration means Filter rising temperature calculating means (ECU2, step 6) for calculating the rising temperature TUDPF of the filter that has been raised by the combustion of fuel in the filter 8; A pre-filter gas temperature detecting means (second exhaust gas temperature sensor 14) provided between the gas system catalyst and the filter 8 and detecting the temperature of the exhaust gas as the pre-filter gas temperature TDPFG, and the detected pre-filter gas temperature TDPFG And a regeneration control means (ECU 2, steps 7 to 9A, 13 to 16) for controlling the regeneration operation of the regeneration means in accordance with the calculated temperature rise TUDPF of the filter.

  According to the exhaust gas purification apparatus for an internal combustion engine, the exhaust system is provided with a catalyst for oxidizing exhaust gas and a filter for collecting particulates (hereinafter referred to as “PM”) in the exhaust gas in order from the upstream side. The unburned fuel is supplied into the exhaust gas upstream of the catalyst by the regeneration means. As a result, the temperature of the filter rises due to, for example, the exhaust gas heated by the unburned fuel burning in the catalyst and flows into the filter. As a result, the PM deposited on the filter burns and the filter is regenerated. .

  In addition, the rising temperature of the filter, which has risen due to the combustion of unburned fuel in the filter during the regeneration operation of the regeneration means, is calculated by the filter rise temperature calculation means and provided between the exhaust system catalyst and the filter. The pre-filter gas temperature detection means detects the temperature of the exhaust gas upstream of the filter as the pre-filter gas temperature. The regeneration control means controls the regeneration operation of the regeneration means in accordance with the pre-filter gas temperature and the rising temperature of the filter. In this way, the regeneration operation is controlled by the fact that the unburned fuel is basically burned by the catalyst as described above, but a part of it is not burned by the catalyst but flows into the filter and burns. This is because the temperature of the filter may increase. In that case, the actual temperature of the filter does not coincide with the exhaust gas temperature detected on the upstream side of the filter, and becomes a value obtained by adding the temperature rise of the filter to this. Therefore, as described above, by controlling the regeneration operation according to not only the pre-filter gas temperature but also the rising temperature of the filter, while supplying unburned fuel without excess or deficiency according to the actual temperature of the filter. Thus, the regeneration operation can be performed appropriately, thereby improving the fuel consumption and preventing the filter from being melted.

  According to a second aspect of the present invention, there is provided an exhaust gas purification apparatus 1 for an internal combustion engine according to the first aspect, wherein an exhaust gas flow rate detecting means (air flow sensor 12, ECU 2, step 4) for detecting a flow rate QEG of the exhaust gas, and an exhaust system catalyst And a pre-catalyst gas temperature detection means (first exhaust gas temperature sensor 13) that is provided upstream of the exhaust gas and detects the temperature of the exhaust gas as the pre-catalyst gas temperature TCATG. A rising temperature TUDPF of the filter is calculated according to at least one of the exhaust gas flow rate QEG and the pre-catalyst gas temperature TCATG (steps 4A to 6).

  According to this configuration, the rising temperature of the filter is calculated according to the detected flow rate of exhaust gas and / or the pre-catalyst gas temperature, that is, the temperature of exhaust gas flowing into the catalyst. The difficulty of burning unburned fuel in the catalyst varies depending on the flow rate of exhaust gas and the temperature of exhaust gas flowing into the catalyst. For example, the higher the exhaust gas flow rate and the lower the temperature of the exhaust gas flowing into the catalyst, the more difficult it is for the unburned fuel to burn in the catalyst, and it becomes easier for the catalyst to pass through the catalyst and flow into the filter. The temperature rise of the filter due to the combustion of fuel becomes larger. Therefore, by calculating the rising temperature of the filter as described above, the calculation can be appropriately performed according to the flow rate of the exhaust gas and the temperature of the exhaust gas flowing into the catalyst, thereby more appropriately performing the regeneration operation of the filter. Can be done.

  According to a third aspect of the present invention, there is provided the exhaust gas purifying apparatus 1 for an internal combustion engine according to the first or second aspect, wherein the filter according to the predetermined target temperature TDPFREF and the rising temperature TUDPF of the filter during the regeneration operation of the regeneration means Target temperature setting means (ECU2, step 14) for setting a target temperature TDPFCMD of the pre-gas temperature TDPFG is further provided, and the regeneration control means regenerates the regeneration means so that the pre-filter gas temperature TDPFG becomes the set target temperature TDPFCMD. The operation is controlled (step 15).

  According to this configuration, the target temperature of the pre-filter gas temperature is set by the target temperature setting means according to the predetermined target temperature of the filter during the regeneration operation and the rising temperature of the filter. Then, by the regeneration operation, the pre-filter gas temperature, that is, the exhaust gas temperature upstream of the filter is controlled to the set target temperature. For this reason, for example, by setting the target temperature of the pre-filter gas temperature by subtracting the rising temperature of the filter from the target temperature of the filter, the actual temperature of the filter is improved to its original predetermined target temperature during the regeneration operation. Therefore, the reproduction operation can be appropriately performed.

  The invention according to claim 4 is the exhaust gas purification apparatus 1 for an internal combustion engine according to any one of claims 1 to 3, wherein the filter temperature is estimated based on the pre-filter gas temperature TDPFG and the filter rising temperature TUDPF. A temperature estimation means (ECU2, step 7) is further provided, and the regeneration control means determines the end timing of the regeneration operation of the regeneration means based on the estimated filter temperature (filter temperature TDPF) (steps 8-9A, 13, 16).

  According to this configuration, the filter temperature estimation means can accurately estimate the actual temperature of the filter during the regeneration operation based on the detected pre-filter gas temperature and the raised temperature of the filter. Further, the end timing of the regeneration operation is determined based on the estimated filter temperature. The combustion speed of PM in the filter changes according to the temperature of the filter, and the higher the temperature of the filter, the larger the speed, and accordingly, the timing for completing the regeneration becomes earlier. Therefore, it is possible to optimally determine the end timing of the regeneration operation based on the estimated filter temperature as described above, thereby making it possible to reliably complete the regeneration and useless unburned fuel after the regeneration is completed. By preventing the supply, fuel consumption can be further improved.

  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. The internal combustion engine (hereinafter referred to as “engine”) 3 is, for example, a four-cylinder type diesel engine mounted on a vehicle (not shown).

  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, and a fuel injection valve (hereinafter referred to as “injector”) 6 (regeneration means) is attached so as to face the combustion chamber 3c. ing.

  The injector 6 is disposed at the center of the top wall of the combustion chamber 3c, and is connected in turn to a high-pressure pump and a fuel tank (both not shown) via a common rail. The fuel in the fuel tank is boosted to a high pressure by a high-pressure pump, then sent to the injector 6 through the common rail, and injected from the injector 6 into the combustion chamber 3c. Further, the fuel injection amount QINJ and the injection timing of the injector 6 are set by the ECU 2, and the valve opening time and valve opening timing of the injector 6 can be obtained by the drive signal from the ECU 2 with the set fuel injection amount QINJ and the injection timing. Controlled.

  A magnet rotor 11a is attached to the crankshaft 3d of the engine 3, and the crank angle sensor 11 is configured by the magnet rotor 11a and the MRE pickup 11b. The crank angle sensor 11 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 an air flow sensor 12 (exhaust gas flow rate detecting means). The air flow sensor 12 detects an intake air amount QA, and a detection signal is output to the ECU 2.

  The exhaust pipe 5 is provided with an oxidation catalyst 7 (catalyst) and a filter 8 in order from the upstream side. The oxidation catalyst 7 oxidizes HC and CO in the exhaust gas and purifies the exhaust gas. The filter 8 collects particulates such as soot in the exhaust gas (hereinafter referred to as “PM”) to reduce PM discharged into the atmosphere. A catalyst (not shown) similar to the oxidation catalyst 7 is supported on the surface of the filter 8.

  Further, the exhaust pipe 5 includes a first exhaust gas temperature sensor 13 (pre-catalyst gas temperature detecting means) and a second exhaust gas temperature sensor 14 (pre-filter gas temperature) immediately upstream of the oxidation catalyst 7 and immediately upstream of the filter 8. Detection means) are provided respectively. The first exhaust gas temperature sensor 13 detects the temperature of the exhaust gas immediately upstream of the oxidation catalyst 7 (hereinafter referred to as “pre-catalyst gas temperature”) TCATG and outputs a detection signal to the ECU 2. The second exhaust gas temperature sensor 14 detects the temperature of the exhaust gas immediately upstream of the filter 8 (hereinafter referred to as “pre-filter gas temperature”) TDPFG and outputs the detection signal to the ECU 2.

  Further, a detection signal representing an operation amount (hereinafter referred to as “accelerator opening”) AP of an accelerator pedal (not shown) is output from the accelerator opening sensor 15 to the ECU 2.

  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 11 to 15 described above are 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 8 according to the determined operating state. To do. In the present embodiment, the ECU 2 constitutes a regeneration means, a filter rise temperature calculation means, a regeneration control means, an exhaust gas flow rate detection means, a target temperature setting means, and a filter temperature estimation means.

  Next, the reproduction control process will be described with reference to FIGS. This process is executed in synchronization with the input of the TDC signal. Further, the regeneration operation of the filter 8 in this process is performed by post-injection in which fuel is injected into the combustion chamber 3c during the expansion stroke or the exhaust stroke, whereby unburned fuel is supplied into the exhaust gas, The filter 8 is regenerated by controlling the temperature to a high temperature and burning the PM deposited on the filter 8.

  First, in step 1 of FIG. 2 (shown as “S1”, the same applies hereinafter), the PM emission amount is searched by searching a PM emission map (not shown) according to the engine speed NE and the fuel injection amount QINJ. PME (hereinafter simply referred to as “PM emission amount”) is calculated. This PM emission amount PME represents the emission amount of PM discharged from the engine 3 per 1 TDC, that is, for each combustion.

  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 fuel injection amount QINJ. The fuel injection amount QINJ is calculated by searching a map (not shown) according to the engine speed NE and the accelerator pedal opening AP.

  Next, it is determined whether or not the reproducing flag F_POSTON is “1” (step 2). When the answer is NO, that is, when the regeneration operation is not being executed, the temperature inside the filter 8 (hereinafter simply referred to as “filter temperature”) TDPF is set to the pre-filter gas temperature TDPFG (step 3).

  On the other hand, if the answer to step 2 is YES and the regeneration operation is being executed, the exhaust gas flow rate QEG is calculated by searching a map (not shown) according to the intake air amount QA and the fuel injection amount QINJ ( Step 4). This map is obtained by experimentally determining the flow rate of exhaust gas and mapping the result according to the intake air amount QA and the fuel injection amount QINJ.

  Next, the slip-through rate PCSR is calculated by searching the PCSR map shown in FIG. 4 according to the calculated exhaust gas flow rate QEG and the pre-catalyst gas temperature TCATG (step 4A). This slip-through rate PCSR represents the ratio of the amount of unburned fuel that has passed through without being burned by the oxidation catalyst 7 out of the amount of unburned fuel supplied into the exhaust gas by post injection. This PCSR map is divided into seven regions corresponding to the exhaust gas flow rate QEG and the pre-catalyst gas temperature TCATG. A predetermined slip-through rate PCSR is assigned to each of these areas, and the number given to each area indicates that the smaller the value, the greater the slip-through ratio PCSR. That is, the slipping rate PCSR is set to a larger value as the exhaust gas flow rate QEG is larger, and the proportion of unburned fuel that is not burned by the oxidation catalyst 7 is higher, and the lower the pre-catalyst gas temperature TCATG is. That is, as the temperature of the exhaust gas flowing into the oxidation catalyst 7 is lower, the unburned fuel is less likely to burn in the oxidation catalyst 7 and more easily passes through the oxidation catalyst 7, and thus is set to a larger value.

  Next, the slip-through amount QPDPF is calculated by multiplying the calculated slip-through rate PCSR by the post-injection amount (hereinafter referred to as “post-injection amount”) QPOST set at that time (step 5). As is apparent from this calculation method, the slip-through amount QPDPF is the amount of unburned fuel that passes through the oxidation catalyst 7 and flows into the filter 8.

Next, using the calculated slip-through amount QPDPF and exhaust gas flow rate QEG, the filter rising temperature TUDPF is calculated by the following equation (1) (step 6).
TUDPF ← QPDPF / (C ・ QEG) (1)
Here, C is a constant and corresponds to the specific heat of the exhaust gas when the slip-through amount QPDPF is regarded as the amount of heat generated when the unburned fuel is combusted. Therefore, the filter rising temperature TUDPF corresponds to an increase in the temperature inside the filter 8 caused by the combustion of the unburned fuel that has passed through the oxidation catalyst 7 in the filter 8.

  Next, the filter temperature TDPF is calculated by adding the calculated filter rising temperature TUDPF to the pre-filter gas temperature TDPFG (step 7).

  In step 8 following step 3 or 7, the PM combustion amount PMB is calculated by searching a table (not shown) based on the filter temperature TDPF. This PM combustion amount PMB is a combustion amount of PM combusted by the filter 8, and is set to a larger value as the filter temperature TDPF is higher in the table. Next, the PM accumulation amount QPMDPF per 1 TDC is calculated by subtracting the PM combustion amount PMB from the PM emission amount PME calculated in Step 1 (Step 9).

  Next, the current PM deposition amount integrated value SQPMDPF is calculated by adding the PM deposition amount QPMDPF calculated in step 9 to the PM deposition amount integrated value SQPMDPF obtained so far (step 9A). This PM accumulation amount integrated value SQPMDPF is reset to a value of 0 when the regeneration of the filter 8 is completed, as will be described later, and therefore represents the amount of PM accumulated on the filter 8 at that time. .

  Next, at step 10 in FIG. 3, it is determined whether or not the reproducing flag F_POSTON is “1”. If the answer is NO and the regeneration operation is not being executed, it is determined whether or not the PM accumulation amount integrated value SQPMDPF calculated in step 9A is larger than a predetermined threshold value PMREF (for example, 9 g) (step 11). ). When this answer is NO, since the amount of PM accumulated in the filter 8 is still small, this processing is terminated on the assumption that the regeneration operation is not executed.

  On the other hand, when the answer to step 11 is YES and the PM accumulation amount integrated value SQPMDPF is larger than the threshold value PMREF, the regeneration flag F_POSTON is set to “1” to start the regeneration operation (step 12). ), Go to step 13. On the other hand, if the answer to step 10 is YES and the playback operation is already being executed, steps 11 and 12 are skipped and the process proceeds to step 13.

  In step 13, it is determined whether or not the PM accumulation amount integrated value SQPMDPF is smaller than the determination value REFIN. The determination value REFIN is set to a small predetermined value close to the value 0. When the answer is NO, a value obtained by subtracting the filter rising temperature TUDPF calculated in step 6 from the predetermined target temperature TDPFREF of the filter 8 is set as the target temperature TDPFCMD of the pre-filter gas temperature TDPFG (step 14). The target temperature TDPFREF of the filter 8 is set to a temperature at which the filter 8 can be reliably regenerated by combustion of the accumulated PM and can be prevented from being melted, for example, 600 ° C.

  Next, the post-injection amount QPOST is calculated by a predetermined feedback control algorithm so that the pre-filter gas temperature TDPFG becomes the target temperature TDPFCMD set in step 14 (step 15), and this process is terminated. Thus, the post-injection with the calculated post-injection amount QPOST is performed by the injector 6 so that the pre-filter gas temperature TDPFG is controlled to the target temperature TDPFCMD.

  On the other hand, when the answer to step 13 is YES and the PM accumulated amount integrated value SQPMDPF becomes smaller than the determination value REFIN, the PM accumulated on the filter 8 is sufficiently burned by executing the regeneration operation in steps 14 and 15. Then, assuming that the PM accumulation amount integrated value SQPMDPF becomes sufficiently small and the regeneration is completed, the regeneration operation is terminated, and the regeneration flag F_POSTON is reset to “0” (step 16). Next, the PM accumulation amount integrated value SQPMDPF is reset to 0 (step 17), and this process is terminated.

  As described above, according to the present embodiment, the target temperature TDPFCMD of the pre-filter gas temperature TDPFG is set to a value obtained by subtracting the filter rising temperature TUDPF from the predetermined target temperature TDPFREF of the filter 8 (step 14). The post injection amount is controlled so that the pre-gas temperature TDPFG becomes the target temperature TDPFCMD (step 15). Therefore, during the regenerating operation, the actual temperature of the filter 8 can be satisfactorily maintained at its original target temperature TDPFREF. In this way, post-injection can be performed appropriately while supplying unburned fuel without excess or deficiency according to the actual temperature of the filter 8, thereby improving fuel efficiency and preventing melt damage of the filter 8. Can do.

  Further, since the filter rising temperature TUDPF is calculated based on the slip-through rate PCSR obtained according to the exhaust gas flow rate QEG and the pre-catalyst gas temperature TCATG (steps 4A to 6), the filter rising temperature TUDPF is appropriately calculated. Therefore, post injection can be performed more appropriately.

  Furthermore, since the filter temperature TDPF is calculated by adding the filter rising temperature TUDPF to the pre-filter gas temperature TDPFG (step 7), the actual temperature of the filter 8 during the regeneration operation can be accurately estimated. Further, the PM accumulation amount QPMDPF is obtained according to the filter temperature TDPF (steps 8 and 9), and when the PM accumulation amount integrated value SQPMDPF (step 9A) obtained by further integrating the PM accumulation amount becomes smaller than the determination value REFIN (step 13). : YES), the reproduction operation is terminated (step 16). Accordingly, regeneration can be completed with certainty, and fuel efficiency can be further improved by preventing wasteful post-injection after completion of regeneration.

  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 by post-injection to the combustion chamber 3c using the injector 6, but the injector is separately provided upstream of the oxidation catalyst 7 in the exhaust pipe 5. So that the fuel can be directly injected into the exhaust pipe 5. In the embodiment, the filter rising temperature TUDPF is calculated according to both the exhaust gas flow rate QEG and the pre-catalyst gas temperature TCATG, but may be calculated according to one of these.

  In the embodiment, the post-injection amount QPOST is calculated so that the pre-filter gas temperature TDPFG becomes the target temperature TDPFCMD. However, without using the target temperature TDPFCMD, only the calculated filter temperature TDPF is used. May be. 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 gist 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 flowchart which shows a reproduction | regeneration control process. It is a flowchart which shows the continuation of FIG. It is an example of the PCSR map used by the process of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust gas purification apparatus 2 ECU (regeneration means, filter rising temperature calculation means, regeneration control means, exhaust gas flow
Quantity detection means, target temperature setting means, filter temperature estimation means)
3 Engine 5 Exhaust pipe (exhaust system)
6 Injector (reproducing means)
7 Oxidation catalyst (catalyst)
8 Filter 12 Air flow sensor (Exhaust gas flow rate detection means)
13 First exhaust gas temperature sensor (pre-catalyst gas temperature detection means)
14 Second exhaust gas temperature sensor (gas temperature detection means before filter)
TUDPF filter rising temperature TDPFG pre-filter gas temperature QEG exhaust gas flow rate TCATG pre-catalyst gas temperature TDPFREF predetermined target temperature for filter TDPFCMD pre-filter gas temperature TDPFG target temperature TDPF filter temperature (estimated filter temperature)

Claims (4)

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;
A catalyst provided upstream of the filter of the exhaust system and oxidizing exhaust gas;
Regenerating means for regenerating the filter by supplying unburned fuel into the exhaust gas upstream of the catalyst;
A filter rise temperature calculation means for calculating an increase temperature of the filter that has been increased by burning unburned fuel in the filter during the regeneration operation of the regeneration means;
A pre-filter gas temperature detecting means that is provided between the catalyst of the exhaust system and the filter and detects the temperature of the exhaust gas as the pre-filter gas temperature;
A regeneration control means for controlling the regeneration operation of the regeneration means in accordance with the detected pre-filter gas temperature and the calculated temperature rise of the filter;
An exhaust gas purifying device for an internal combustion engine, comprising: Exhaust gas flow rate detecting means for detecting the flow rate of exhaust gas;
A pre-catalyst gas temperature detecting means provided upstream of the catalyst in the exhaust system and detecting the temperature of the exhaust gas as the pre-catalyst gas temperature;
2. The exhaust gas of the internal combustion engine according to claim 1, wherein the filter rising temperature calculating means calculates the rising temperature of the filter according to at least one of the detected exhaust gas flow rate and pre-catalyst gas temperature. Purification equipment. A target temperature setting means for setting a target temperature of the pre-filter gas temperature according to a predetermined target temperature of the filter and a rising temperature of the filter during the regeneration operation of the regeneration means;
The exhaust gas purification of an internal combustion engine according to claim 1 or 2, wherein the regeneration control means controls the regeneration operation of the regeneration means so that the pre-filter gas temperature becomes the set target temperature. apparatus. Filter temperature estimating means for estimating the temperature of the filter based on the pre-filter gas temperature and the rising temperature of the filter;
The exhaust gas of an internal combustion engine according to any one of claims 1 to 3, wherein the regeneration control means determines the end timing of the regeneration operation of the regeneration means based on the estimated filter temperature. Purification equipment.

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