JP2006029301A - Exhaust emission control device for compression ignition internal combustion engine and exhaust emission control method for compression ignition internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten time required for oxidizing and removing particulates collected by a filter and more successfully oxidize and remove the particulates, in exhaust emission control of a compression ignition internal combustion engine. <P>SOLUTION: The compression ignition internal combustion engine is provided with an intake throttle valve, an exhaust throttle valve and the filter in which a catalyst having an oxidation function is carried and which collects particulates in exhaust gas. In the compression ignition internal combustion engine, the temperature of the filter is increased by: controlling injection timing of main injection injm and post-injection inja to a timing delay state when openings of the intake throttle valve and the exhaust throttle valve are set to be a throttle side opening (opening 10%) and an opening at the time of first temperature rise (10%), respectively; and then shifting the opening of the intake throttle valve from the throttle side opening (opening 10%) to an open side opening (opening 100%) and shifting the opening of the exhaust throttle valve to an opening at the time of second temperature rise (50%) more widely opened compared to the opening at the time of first temperature rise (10%). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exhaust purification device that performs exhaust purification of a compression ignition internal combustion engine, and an exhaust purification method for performing exhaust purification.

  A filter is disposed in the exhaust passage to collect particulate matter contained in the exhaust from the internal combustion engine. In this case, it is necessary to periodically oxidize and remove the particulate matter collected by the filter to restore the collection ability of the filter.

  Here, a technique for increasing the temperature of exhaust gas discharged from an internal combustion engine by adjusting the opening of an exhaust throttle valve provided in an exhaust passage is disclosed. (For example, see Patent Document 1). In this technique, the exhaust temperature is raised to a temperature suitable for removing particulate matter by adjusting the opening of the exhaust throttle valve based on the temperature near the exhaust inlet of the filter.

Similarly, as a technique for oxidizing and removing particulate matter collected by the filter, a technique for adjusting the opening of the intake throttle valve provided in the intake passage and the opening of the exhaust throttle valve provided in the exhaust passage is used. (See, for example, Patent Document 2). In this technology, by adjusting the opening of the intake throttle valve, the amount of heat removed from the filter by the exhaust is suppressed, and the opening of the exhaust throttle valve is adjusted according to the opening of the intake throttle valve. By increasing the back pressure, the exhaust temperature is raised to a temperature suitable for oxidizing and removing particulate matter.
Japanese Patent No. 3024780 JP 2003-343287 A JP-A-3-233121 JP 2002-213229 A

  In order to oxidize and remove the particulate matter collected by the filter installed in the exhaust passage of the compression ignition internal combustion engine, the exhaust temperature is raised by the post-injection after the main injection, and thus the temperature of the filter is raised. . Furthermore, by limiting the amount of exhaust flowing into the filter, the amount of heat energy taken away by the exhaust is reduced, and the temperature of the filter can be raised. In such a case, since the amount of exhaust gas flowing into the filter is relatively small, the heat propagation speed in the filter is low, the time required for temperature rise of the filter is increased, or the collected particulate matter is good. However, it may be difficult to oxidize and remove.

  It is also possible to raise the exhaust gas temperature and raise the temperature of the filter by raising the back pressure of the internal combustion engine. However, if the exhaust flow rate flowing through the exhaust passage is simply limited to increase the back pressure, it is necessary to limit the exhaust flow rate itself to a relatively small amount in order to prevent damage to the internal combustion engine. Therefore, the propagation speed of heat in the filter is lowered, the time required for the temperature rise of the filter is increased, or it may be difficult to satisfactorily oxidize and remove the collected particulate matter.

  In the present invention, in view of the above problems, in exhaust purification of a compression ignition internal combustion engine, the time required for oxidizing and removing particulate matter collected by the filter is shortened, and better particulate matter is removed by oxidation. The purpose is to do.

  In the present invention, in order to solve the above-mentioned problem, first, in the invention relating to the exhaust gas purification apparatus for a compression ignition internal combustion engine, it is carried out when the collected particulate matter is oxidized and removed by raising the temperature of the filter. Focusing on the injection timing of main injection and post-injection, the opening of the intake throttle valve, and the opening of the exhaust throttle valve. This is because the exhaust temperature can be raised by setting the injection timing of the main injection and the post-injection to a retarded state, and the temperature of the filter can be raised by controlling the intake air amount and the back pressure in this state. This is because it is possible to promote or maintain the filter at a high temperature.

  Therefore, the present invention is an exhaust emission control device for a compression ignition internal combustion engine, and adjusts the intake flow rate of the intake passage of the compression ignition internal combustion engine and the exhaust flow rate of the exhaust passage of the compression ignition internal combustion engine. An exhaust throttle valve, a filter carrying a catalyst having an oxidation function and collecting particulate matter in the exhaust, an intake throttle valve opening control means for controlling the opening degree of the intake throttle valve, and the exhaust throttle valve Exhaust throttle valve opening control means for controlling the opening of the engine, fuel injection conditions for main injection at a timing near the compression top dead center, and fuel injection after the main injection, and combustion of injected fuel by the main injection A fuel injection control means for controlling a fuel injection condition for post-injection in which at least a part of the fuel is burned, and an opening degree of the intake throttle valve is set to a throttle side opening degree by the intake throttle valve opening degree control means, and the exhaust gas Throttle valve opening control hand By setting the opening of the exhaust throttle valve to the opening at the time of the first temperature rise, the first filter temperature raising means for raising the temperature of the filter, and the temperature rise of the filter by the first filter temperature raising means is performed. When the fuel injection control means controls the fuel injection timing of the main injection and the post-injection to a retarded state, the intake throttle valve opening control means controls the opening degree of the intake throttle valve. The opening at the second temperature rise from the throttle opening to the opening at the opening, and the exhaust throttle valve opening control means opens the opening of the exhaust throttle valve from the opening at the first temperature rise. And a second filter temperature raising means for raising the temperature of the filter.

  The fuel injection control means controls fuel injection conditions for main injection and post-injection. As the fuel injected by these injections burns, the exhaust gas temperature rises, and the exhaust gas raises the temperature of the filter. The fuel injection conditions here are parameters relating to fuel injection, and examples include fuel injection timing and fuel injection amount.

  The post-injection is an injection performed after the main injection in the compression ignition internal combustion engine, and the fuel injected by the post-injection is exposed to the combustion heat generated by the combustion of the injected fuel by the main injection. , At least a portion of which is subjected to combustion. Accordingly, combustion torque is generated even with the fuel injected by post-injection.

  In addition, since the filter carries a catalyst having an oxidation function, the temperature of the filter is raised by oxidation heat generated by oxidizing the fuel contained in the exhaust gas by the oxidation function. Examples of the catalyst having this oxidation function include a so-called storage reduction type NOx catalyst. The fuel injected by the above-described post-injection and not used for combustion is supplied to the filter through the exhaust gas, and contributes to the temperature rise of the filter by oxidation heat generated by the catalyst carried on the filter. It will be.

  Here, the filter is provided in the exhaust passage of the compression ignition internal combustion engine, and has the ability to collect particulate matter in the exhaust. Since the collection capacity is not infinite, when a certain amount of particulate matter is collected, the filter is heated up to oxidize and remove the collected particulate matter to regenerate the collection ability of the filter. It is necessary to plan.

Therefore, the temperature of the filter is raised by the first filter temperature raising means. The feature of the temperature rise of the filter by the first filter temperature raising means is that the exhaust flow flowing into the filter is suppressed to prevent the heat of the filter from being carried away by the exhaust, and the back pressure in the exhaust passage is raised. This raises the exhaust temperature and raises the temperature of the filter. Therefore, the throttle side opening is the opening of the intake throttle valve that can suppress the amount of exhaust flowing into the filter and avoid the heat energy of the filter being taken away by the exhaust. That is, the throttle-side opening is an intake throttle valve that is normally set in accordance with the operating conditions such as the engine load and engine speed of a compression ignition internal combustion engine for the purpose of suppressing a decrease in thermal energy of the filter. The opening is further narrowed down from the opening. Further, the first temperature elevation opening is the opening of the exhaust throttle valve for increasing the back pressure in the exhaust passage, and preferably increases the exhaust temperature within a range that does not adversely affect the combustion of the internal combustion engine. It is the opening degree of the exhaust throttle valve for making it.

  When the temperature of the filter is raised by the first filter temperature raising means, it is possible to increase the temperature of the filter by raising the exhaust temperature by performing post-injection in addition to the main injection. . However, post-injection does not necessarily have to be performed at this stage.

  In order to further promote the temperature rise of the filter, the temperature of the filter is raised by the second filter temperature raising means. The characteristic feature of the temperature rise of the filter by the second filter temperature raising means is that the injection timing of the main injection and the post-injection is first retarded by the fuel injection control means. The retarded state means that the fuel injection timings of the main injection and the post-injection are retarded compared to the case where the temperature of the filter is not raised or the temperature of the filter is raised by the first filter temperature raising means. It means that it has been moved to the side. When the fuel injection timings of the main injection and the post-injection are retarded, the time required for the combustion gas to be discharged from the compression ignition internal combustion engine is shortened. Therefore, compared with the case where the fuel injection timing is not retarded The exhaust temperature rises. Therefore, the retarded state means that the fuel injection timing is further set from the fuel injection timing that is normally set corresponding to the operation state such as the engine load and engine speed of the compression ignition internal combustion engine for the purpose of raising the exhaust gas temperature. It can be said that the state is shifted to the retard side.

  If the post-injection is not performed when the temperature of the filter is raised by the first filter temperature raising means, the main angle that is retarded when the temperature of the filter is raised by the second filter temperature raising means is set. The injection timing of the post-injection is controlled at the time when at least part of the fuel is combusted by the combustion of the injected fuel.

  Further, the characteristic feature of the temperature rise of the filter by the second filter temperature raising means is that the opening of the intake throttle valve is opened to the open side while the injection timings of the main injection and the post-injection are retarded. At the same time, the opening of the exhaust throttle valve is set to the opening at the time of the second temperature increase.

  Here, the opening side opening degree is an opening degree in a direction in which the intake flow rate increases from the throttle side opening degree in order to increase the heat propagation speed in the filter. And the combustion state of the fuel in main injection and post-injection changes because the opening degree of the intake throttle valve is made the opening side opening degree and the intake flow rate increases. That is, while the fuel injected by the main injection is promoted by a large amount of intake air, the fuel injected by the post-injection is less likely to be combusted by the combustion promotion of the fuel.

  As a result, the heat propagation speed in the filter is increased by setting the opening degree of the intake throttle valve to the opening side opening degree. Furthermore, since the fuel injected by post-injection is less likely to be used for combustion, the amount of fuel supplied to the filter via the exhaust increases. As a result, the heat of oxidation generated by the catalyst supported on the filter can be increased, which can contribute to the temperature rise of the filter.

  Further, the opening degree at the second temperature rise is an opening degree of the exhaust throttle valve for maintaining the back pressure in the exhaust passage at a pressure suitable for the temperature rise of the filter, and the intake throttle valve is opened on the open side. This is the degree of opening of the exhaust throttle valve that does not adversely affect the combustion of the compression ignition internal combustion engine due to the increased exhaust flow rate. Accordingly, the second temperature elevation opening is an opening at which the exhaust throttle valve is opened more than the first temperature elevation opening.

  Thereby, even when the temperature of the filter is raised by the second filter temperature raising means, the back pressure in the exhaust passage is controlled to be relatively high, and the temperature rise of the filter is further promoted.

  As described above, in the above-described exhaust gas purification apparatus for a compression ignition internal combustion engine, the first filter temperature raising means and the second filter temperature raising means can reduce the time required for oxidizing and removing the particulate matter collected on the filter. At the same time, the particulate matter is better removed by oxidation, and the unburned particulate matter in the filter is suppressed.

  Further, in the case where the exhaust gas purification apparatus of the compression ignition internal combustion engine further includes a filter temperature estimating means for estimating or detecting the temperature of the filter, the second filter temperature raising means includes the main injection and the rear After the fuel injection timing of the injection is controlled to be retarded and the filter temperature estimated or detected by the filter temperature estimating means is higher than a predetermined temperature, the opening degree of the intake throttle valve is set to The opening of the exhaust throttle valve may be set to the opening at the time of the second temperature increase while the opening is set to the opening side.

  Said predetermined temperature is temperature relevant to the active state of the catalyst which has the oxidation function currently carry | supported by the filter. That is, when the filter temperature is equal to or lower than the predetermined temperature, the catalyst has not reached the active state, so that it is difficult to generate sufficient oxidation heat by the fuel component in the exhaust gas. Therefore, even if the exhaust gas flow rate flowing into the filter increases, the temperature of the filter is hardly increased. Therefore, since the catalyst reaches an active state when the filter temperature becomes higher than a predetermined temperature, in such a case, the second filter temperature raising means sufficiently generates heat of oxidation due to the fuel component in the exhaust, and the exhaust By increasing the heat propagation speed in the filter by increasing the flow rate, it is possible to quickly raise the temperature of the filter.

  In the exhaust gas purification apparatus for a compression ignition internal combustion engine as described above, the second filter temperature raising means may be configured such that the exhaust throttle valve opening degree is set to the second temperature raising opening degree by the exhaust throttle valve opening degree control means. After that, the intake throttle valve opening degree control means may set the opening degree of the intake throttle valve to the opening side opening degree.

  That is, when the temperature of the filter is raised by the second filter temperature raising means, the change of the opening of the exhaust throttle valve is performed before the change of the opening of the intake throttle valve, so that the back pressure in the exhaust passage rises rapidly. Thus, adverse effects on the internal combustion engine can be more reliably suppressed.

  Secondly, in the present invention, in order to solve the above-described problem, the injection timing of the main injection and the post-injection, the intake throttle, which is performed when the collected particulate matter is oxidized and removed by raising the temperature of the filter. We focused on the opening of the valve and the opening of the exhaust throttle valve. This is because the exhaust temperature can be raised by setting the injection timing of the main injection and the post-injection to a retarded state, and the temperature of the filter can be raised by controlling the intake air amount and the back pressure in this state. This is because it is possible to promote or maintain the filter at a high temperature.

Therefore, the present invention carries an intake throttle valve for adjusting the intake flow rate of the intake passage of the compression ignition internal combustion engine, an exhaust throttle valve for adjusting the exhaust flow rate of the exhaust passage of the compression ignition internal combustion engine, and a catalyst having an oxidation function. An exhaust gas purification method for a compression ignition internal combustion engine comprising a filter for collecting particulate matter in exhaust gas, wherein the opening of the intake throttle valve is set to a throttle side opening and the exhaust throttle valve is opened. A first temperature raising step for raising the temperature of the filter by setting the degree of opening at the first temperature raising time, a main injection at a timing near the compression top dead center, and a fuel injection after the main injection, After controlling the fuel injection timing of each post-injection in which at least a part of the fuel is combusted by combustion of the injected fuel by the main injection to a retarded state, and when the temperature of the filter is higher than a predetermined temperature,
The opening degree of the intake throttle valve is changed from the throttle side opening degree to the opening side opening degree, and the opening degree of the exhaust throttle valve is opened from the first temperature raising opening degree. And a second filter temperature raising step for raising the temperature of the filter.

  Regarding the throttle side opening, the opening side opening, the first temperature elevation opening, the second temperature elevation opening, the predetermined temperature, and the retarded state of the fuel injection timing in the exhaust purification method of the compression ignition internal combustion engine, Same as the throttle side opening, the opening side opening, the first temperature rise opening, the second temperature rise opening, the predetermined temperature, and the retarded state of the fuel injection timing in the above-described exhaust gas purification apparatus for a compression ignition internal combustion engine. is there.

  Therefore, the exhaust purification method of the compression ignition internal combustion engine can reduce the time required for oxidizing and removing the particulate matter collected by the filter, and can better oxidize and remove the particulate matter. The remaining unburned particulate matter is suppressed.

  In the exhaust purification of a compression ignition internal combustion engine, it is possible to reduce the time required for oxidizing and removing particulate matter collected by the filter and to perform better oxidizing and removing particulate matter.

  Here, an embodiment of an exhaust gas purification apparatus for a compression ignition internal combustion engine and an exhaust gas purification method for a compression ignition internal combustion engine according to the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a compression ignition internal combustion engine (hereinafter referred to as “internal combustion engine”) 1 to which the present invention is applied and a control system thereof. The internal combustion engine 1 is a compression ignition type internal combustion engine having four cylinders 2. Further, a fuel injection valve 3 for directly injecting fuel into the combustion chamber of the cylinder 2 is provided. The fuel injection valve 3 is connected to a pressure accumulation chamber 4 that accumulates fuel at a predetermined pressure. An intake branch pipe 7 is connected to the internal combustion engine 1, and each branch pipe of the intake branch pipe 7 is connected to a combustion chamber via an intake port. Similarly, an exhaust branch pipe 12 is connected to the internal combustion engine 1, and each branch pipe of the exhaust branch pipe 12 is connected to a combustion chamber via an exhaust port. Here, the intake port and the exhaust port are provided with an intake valve and an exhaust valve, respectively.

  The intake branch pipe 7 is connected to the intake pipe 8. Further, an intake throttle valve 10 that adjusts the flow rate of the intake air flowing through the intake pipe 8 is located at a portion of the intake pipe 8 that is located immediately upstream of the intake branch pipe 7. An air flow meter 9 for detecting the amount of intake air flowing through the pipe 8 is provided. The intake throttle valve 10 is provided with an intake throttle actuator 11 that is configured by a step motor or the like and that opens and closes the intake throttle valve 10. On the other hand, the internal combustion engine 1 is provided with an EGR device 21. The EGR device 21 recirculates a part of the exhaust gas flowing through the exhaust branch pipe 12 to the intake branch pipe 7. The EGR device 21 includes an EGR passage 22 extending from the exhaust branch pipe 12 (upstream side) to the intake branch pipe 7 (downstream side), and an EGR for cooling EGR gas provided in order from the upstream side on the EGR passage 22. A cooler 23 and an EGR valve 24 for adjusting the flow rate of EGR gas are included.

  An intake pipe 8 positioned between the air flow meter 9 and the intake throttle valve 10 is provided with a compressor side of a supercharger 16 that operates using exhaust energy as a drive source. A turbine side is provided. Further, an intercooler 15 is provided in the intake pipe 8 downstream of the supercharger 16 for cooling the intake air that has been pressurized by the supercharger 16 and has reached a high temperature. Further, the turbine side of the supercharger 16 is connected to an exhaust pipe 13, and the exhaust pipe 13 is connected to a muffler downstream. A filter 14 that purifies the exhaust from the internal combustion engine 1 is provided in the middle of the exhaust pipe 13.

  The filter 14 has the ability to collect particulate matter in the exhaust gas. Further, a so-called storage reduction type NOx catalyst (hereinafter referred to as “NOx catalyst”), which is a kind of catalyst having an oxidation function and purifies by storing and reducing NOx in the exhaust, is supported on the surface. Yes. An oxidation catalyst other than the NOx catalyst and having an oxidation function may be supported on the filter 14.

  An exhaust throttle valve 17 that adjusts the flow rate of the exhaust gas flowing in the exhaust pipe 13 is provided in a portion located downstream of the filter 14. The exhaust throttle valve 17 is provided with an exhaust throttle actuator 18 that is configured by a step motor or the like and that drives the exhaust throttle valve 17 to open and close.

  Further, a battery 30 that stores electrical energy from an alternator (not shown) that is driven by the engine output of the internal combustion engine 1 and an auxiliary device (such as glow) that is driven by the power supplied from the battery 30 are provided in the internal combustion engine 1. Is provided. The flow of electrical energy from the alternator to the battery 30 and the flow of electrical energy from the battery 30 to the auxiliary machine 31 are indicated by solid arrows in the figure.

  Here, the internal combustion engine 1 is provided with an electronic control unit (hereinafter referred to as “ECU”) 20 for controlling the internal combustion engine 1. The ECU 20 includes a CPU, a ROM, a RAM, and the like for storing various programs and maps to be described later, and controls the operating conditions of the internal combustion engine 1 according to the operating conditions of the internal combustion engine 1 and the driver's request. Unit. The flow of signals between the ECU 20 and each element is indicated by dotted arrows in the figure.

  Here, the fuel injection valve 3 performs an opening / closing operation by a control signal from the ECU 20. That is, according to a command from the ECU 20, the fuel injection timing and the injection amount in the fuel injection valve 3 are controlled for each injection valve in accordance with the operation state such as the engine load of the internal combustion engine 1 and the engine rotation speed. Further, the EGR valve 24, the intake throttle actuator 11, the exhaust throttle actuator 18 and the like are also controlled in accordance with commands from the ECU 20, thereby adjusting the EGR gas amount, the intake flow rate, and the exhaust flow rate. Further, the auxiliary machine 31 is also driven in accordance with a command from the ECU 20 according to the operating state of the internal combustion engine 1.

  Further, an accelerator opening sensor 26 is electrically connected to the ECU 20, and the ECU 20 receives a signal corresponding to the accelerator opening and calculates an engine load required for the internal combustion engine 1 based on the signal. The crank position sensor 25 is electrically connected to the ECU 20, and the ECU 20 receives a signal corresponding to the rotation angle of the output shaft of the internal combustion engine 1, and the engine rotational speed of the internal combustion engine 1, the engine rotational speed and the gear. The vehicle speed or the like of the vehicle on which the internal combustion engine 1 is mounted is calculated from the ratio or the like. Further, an exhaust temperature sensor 27 provided in the exhaust passage on the upstream side of the filter 14 is electrically connected to the ECU 20, and the ECU 20 detects the temperature of the exhaust gas flowing into the filter 14 (hereinafter also referred to as “entry gas temperature”). get.

  In the internal combustion engine 1 configured as described above, the particulate matter in the exhaust gas is collected by the filter 14, so that the release of the particulate matter to the atmosphere is suppressed. However, when the amount of particulate matter collected by the filter 14 increases, the back pressure in the exhaust pipe 13 increases and affects the combustion of the internal combustion engine 1. In particular, when the engine load of the internal combustion engine 1 is low, the exhaust temperature is low, so that the oxidation removal of particulate matter in the filter 14 is not promoted, and the amount of particulate matter collected increases.

Therefore, in order to oxidize and remove the particulate matter collected by the filter 14, it is necessary to raise the temperature of the filter 14 and maintain the temperature at which the particulate matter is oxidized and removed. Therefore, by restricting the amount of exhaust flowing into the filter 14, the amount of heat energy taken away by the exhaust is reduced, and the back pressure in the exhaust pipe 13 is increased to raise the exhaust temperature, thereby increasing the filter 14. Temperature is achieved. Further, the exhaust temperature is increased by post-injection performed after the main injection from the fuel injection valve 3.

  However, in such a case, since the amount of exhaust gas flowing into the filter 14 is relatively small, the propagation speed of heat in the filter 14 is low, and the time required to raise the temperature of the filter 14 becomes long. Moreover, it can be in the state where the particulate matter remains unburned locally due to the low heat propagation speed.

  Therefore, the exhaust gas purification device for the internal combustion engine 1 and the exhaust gas purification of the internal combustion engine 1 for reducing the time required for raising the temperature of the filter 14 as much as possible and eliminating the unburned particulate matter better and oxidizing the internal combustion engine 1. The method will be described below. The exhaust emission control device for the internal combustion engine 1 is mainly stored in the fuel injection valve 3, the filter 14, the intake throttle valve 10, the exhaust throttle valve 17 and the ECU 20 of the internal combustion engine 1 and executes a control program described later. Composed of etc.

  FIG. 2 is a view showing a state of fuel injection from the fuel injection valve 3 according to the opening degrees of the intake throttle valve 10 and the exhaust throttle valve 17 when the temperature of the filter 14 is increased. 2A, 2 </ b> B, and 2 </ b> C, the upper stage represents the fuel injection timing, the middle stage represents the opening degree of the intake throttle valve 10, and the lower stage represents the opening degree of the exhaust throttle valve 17. ing. Here, in the fuel injection, the fuel injection represented by injm is a so-called main injection, and is a fuel injection performed at a time near the compression top dead center when normal combustion is performed in the internal combustion engine 1. The fuel injection injp performed at a timing earlier than the main injection injm is a pre-injection, and the fuel injection inja performed at a timing later than the main injection injm is a post-injection.

  3 shows the temperature transition of the filter 14 (indicated by L1 in FIG. 3) when the fuel injection control and the opening control of the intake throttle valve 10 and the exhaust throttle valve 17 shown in FIG. 2 are performed. It is a figure which shows transition (it shows with the line L2 in FIG. 3) of a line and entering gas temperature.

  FIG. 2A shows a control (hereinafter referred to as “first increase”) of fuel injection performed first when the ECU 20 determines to increase the temperature of the filter 14 from various conditions (time T1 shown in FIG. 3). It is referred to as “temperature control”). At this time, the opening degree of the intake throttle valve 10 is fixed to about 10% opening degree (hereinafter referred to as “throttle side opening degree”) when the fully opened opening degree is 100%, and flows through the intake pipe 8. The flow rate of intake air is limited to a relatively small amount. As a result, the flow rate of the exhaust gas flowing into the filter 14 is reduced, so that the amount of heat taken away by the exhaust gas is reduced. This throttle-side opening is an opening that is further throttled than the opening of the intake throttle valve 10 that is normally set corresponding to the operating state of the internal combustion engine 1 such as the engine load and the engine speed.

  Further, the opening degree of the exhaust throttle valve 17 is fixed to an opening degree of about 10% (hereinafter referred to as “first temperature raising opening degree”) when the fully opened opening degree is 100%. The flow rate of the intake air flowing through is limited to a relatively small amount. As a result, the back pressure rises in the exhaust pipe 13 upstream from the portion where the exhaust throttle valve 17 is provided, so that the engine load of the internal combustion engine 1 substantially increases and the exhaust temperature rises. Note that the opening at the time of the first temperature increase must be such that the combustion of the internal combustion engine 1 becomes excessively unstable due to the increase in the back pressure and the engine elements of the internal combustion engine 1 are not damaged.

  In the fuel injection from the fuel injection valve 3, the post-injection inja is performed at the timing T1. In the post-injection inja, at least a part of the fuel injected by the post-injection inja is burned from the fuel injection valve 3 by the combustion heat generated by burning the fuel injected by the main injection. Note that the fuel injection timing when the first temperature raising control is being performed is a fuel injection timing that is normally set in accordance with the operating state of the internal combustion engine 1 such as the engine load and the engine speed.

  As described above, as shown in FIG. 3, when the first temperature rise control is performed at the time T <b> 1, the incoming gas temperature rises and the temperature of the filter 14 also rises. The temperature rise of the filter 14 performed through the above first temperature rise control corresponds to the temperature rise of the filter 14 executed by the first filter temperature raising means in the present invention.

  Next, FIG. 2B is a diagram showing control such as fuel injection at the time of the second temperature increase control performed in place of the above-described first temperature increase control at time T2 after a predetermined time has elapsed from time T1. is there. In the second temperature rise control, the injection timing of the pre-injection injp, the main injection injm, and the post-injection inja performed in the first temperature rise control is shifted to the retard side, and the post-injection inja is changed to the first post-injection inja1. And post-injection inja2. Further, the opening degree of the intake throttle valve 10 and the exhaust throttle valve 17 at this time is the throttle side opening degree (10%) and the first opening degree opening degree (10%), respectively, as in the first temperature raising control. Is set to

  Here, the injection timing of the first post-injection inja1 is a time at which at least a part of the fuel injected by the first post-injection inja1 is used for the combustion of the injected fuel by the main injection injm shifted to the retarded angle side. Further, the injection timing of the second post-injection inja2 is a time when at least a part of the fuel injected by the second post-injection inja2 is used for combustion of the injected fuel by the first post-injection inja1.

  By these first post injection inja1 and second post injection inja2, the combustion of fuel in the cylinder 2 is performed at a relatively late timing. Therefore, as shown in FIG. 3, the exhaust gas temperature rapidly increases after the time T2 when the second temperature raising control is performed. Even when the post-injection is only the first post-injection inja1, the degree of increase in the exhaust temperature is reduced, but a certain degree of increase in the exhaust temperature can be obtained.

  At this time, since the opening of the intake throttle valve 10 is set to the throttle side opening (10%), the amount of heat removed from the filter 14 by the exhaust is suppressed, and the opening of the exhaust throttle valve 17 is Since the opening is set at the first temperature elevation (10%), the exhaust temperature rises due to the back pressure rise.

  By this second temperature rise control, the exhaust temperature rises rapidly, and the amount of heat removed from the filter 14 by the exhaust is suppressed, so that the temperature of the filter 14 reaches nearly 500 degrees as shown in FIG. To rise. However, the exhaust flow rate is suppressed by setting the opening of the intake throttle valve 10 to the throttle side opening (10%) and the opening of the exhaust throttle valve 17 to the first temperature increase opening (10%). Therefore, the heat propagation speed in the filter 14 is low, and the temperature rise of the filter 14 becomes slow, and the temperature at which the particulate matter collected by the filter 14 can be efficiently oxidized and removed (for example, 600 degrees). It takes a relatively long time to raise the temperature of the filter 14 to). Furthermore, since the heat propagation speed is low, there is a possibility that the particulate matter may remain locally burned.

  Therefore, when the temperature of the filter 14 becomes relatively high and the temperature change becomes gradual (time T3 in FIG. 3), the third temperature increase control described below is used instead of the second temperature increase control described above. Is done. The third temperature rise control is the control shown in FIG. 2C, and the control related to the fuel injection timing from the fuel injection valve 3 is not changed from the time of the second temperature rise control. The difference between the third temperature raising control and the second temperature raising control is that the opening degree of the intake throttle valve 10 is changed from the throttle side opening degree (10%) to the opening side opening degree (100%). The opening degree of the throttle valve 17 is changed from the first temperature increase opening (10%) to the second temperature increase opening (50%).

When the opening degree of the intake throttle valve 10 is changed from the throttle side opening degree (10%) to the closing side opening degree (100%) by the third temperature raising control, the intake air flow rate into the cylinder 2 is changed. Thereby, the combustion condition of the injected fuel by the front injection injp and the main injection injm is improved, and the combustion speed of these fuels is increased. Therefore, the amount of fuel injected by the first post-injection inja1 used for the combustion of fuel by the main injection injm decreases, and the amount of fuel injected by the second post-injection inja2 used for the combustion of fuel by the first post-injection inja1 in the same manner. Decrease.

  As a result, the amount of fuel in the exhaust gas increases due to a decrease in the amount of fuel provided for combustion in the fuel injected by the first post injection inja1 and the second post injection inja2. The fuel in the exhaust gas is oxidized by the NOx catalyst supported on the filter 14 so that the temperature of the filter 14 is increased. When the third temperature raising control is performed, the exhaust temperature is lowered as shown in FIG. 3 because the opening of the intake throttle valve 10 is set to the open side opening (100%). The temperature of the filter 14 is maintained at a high temperature by the oxidation heat in the NOx catalyst.

  Here, since the opening degree of the intake throttle valve 10 is set to the opening side opening degree (100%), the exhaust gas flow rate increases, and the heat propagation speed in the filter 14 increases. Therefore, the temperature of the filter 14 can be increased as quickly as possible to a temperature at which the collected particulate matter can be oxidized and removed.

  Further, the reason why the opening of the exhaust throttle valve 17 is changed from the opening at the first temperature increase (10%) to the opening at the second temperature increase (50%) is that the exhaust pressure is increased by increasing the back pressure in the exhaust pipe 13. This is because the back pressure is excessively increased and the internal combustion engine is prevented from being damaged by raising the temperature and opening the intake throttle valve 10 to the opening side opening (100%) as described above. In the present embodiment, the opening at the time of the second temperature increase is 50%, but the temperature of the filter 14 is increased in view of the fact that the intake flow rate varies depending on the operating state of the internal combustion engine 1. What is necessary is just to control the opening degree at the time of a 2nd temperature increase according to intake flow volume so that it may become a suitable back pressure. In addition, the numerical values of the opening side opening degree, the throttle side opening degree, the first temperature raising opening degree, and the second temperature raising opening degree are merely examples, and are not limited to the above numerical values. Individual specific settings may be made according to the characteristics of the engine. The same applies to the description of the following examples.

  The temperature rise of the filter 14 performed through the second temperature rise control and the third temperature rise control corresponds to the temperature rise of the filter executed by the second filter temperature raising means in the present invention.

  Here, when the temperature of the filter 14 is increased by performing the third temperature increase control (case 1), the temperature of the filter 14 is increased by the second temperature increase control without using the third temperature increase control. FIG. 5 and FIG. 6 show the difference in temperature rise of the filter 14 in the case (case 2). FIG. 4 shows a schematic configuration of the filter 14 and measurement points for measuring the temperature rise of the filter 14.

  As shown in FIG. 4, the temperature rise measurement points in the filter 14 were performed at three points on the central axis A1 and the peripheral vicinity A2 of the filter 14. These three points are locations separated from the exhaust inflow side end surface 14a of the filter 14 by 20 mm, 75 mm, and 130 mm, respectively.

  FIG. 5 shows the temperature transition at three points on the central axis A1, the line L3 shows the temperature transition at a location 20 mm away from the exhaust inflow end surface 14a, and the line L4 shows the temperature transition at a location 75 mm away from the exhaust inflow end surface 14a. A line L5 represents a temperature transition at a location 130 mm away from the exhaust inflow end face 14a. 5A corresponds to case 1 and FIG. 5B corresponds to case 2. As shown in FIG. 5, by performing the third temperature increase control, the time required for the temperature of the filter 14 to rise from around 250 degrees to around 630 degrees is shortened.

FIG. 6 shows the temperature transition at three points on the vicinity A2, the line L6 shows the temperature transition at a location 20 mm away from the exhaust inflow end surface 14a, and the line L7 shows the temperature transition at a location 75 mm away from the exhaust inflow end surface 14a. The temperature transition, line L8 represents the temperature transition at a location 130 mm away from the exhaust inflow end face 14a. 6A corresponds to case 1 and FIG. 6B corresponds to case 2. As shown in FIG. 6, by performing the third temperature rise control, the maximum temperature reached at the periphery of the filter 15 rises, and the temperature distribution at the three points is more dense. That is, this means that by performing the third temperature rise control, the heat propagation speed in the filter 14 is increased, which contributes to the rapid temperature rise of the filter 14.

  Here, FIG. 7 shows a flowchart regarding the temperature increase control of the filter 14 (hereinafter referred to as “filter temperature increase control”) using the first temperature increase control, the second temperature increase control, and the third temperature increase control described above. . Further, FIG. 8 shows the transition of the filter temperature (shown in FIG. 8 (a)) and the transition of the opening degree of the exhaust throttle valve 17 (shown in FIG. 8 (b)) when the filter temperature raising control of FIG. 7 is performed. ), The change in the opening of the intake throttle valve 10 (shown in FIG. 8C), the change in the post-injection amount (shown in FIG. 8D), and the change in the back pressure (FIG. 8E). Respectively). This filter temperature increase control is performed by the ECU 20. The filter temperature increase control will be described below.

  In S101, it is determined whether or not the accumulation amount of particulate matter (hereinafter referred to as “PM”) on the filter 14 exceeds a predetermined accumulation amount S1. Here, the predetermined accumulation amount S1 is a threshold value of the PM accumulation amount when it is determined that the collection ability of the filter 14 needs to be regenerated. Further, the PM accumulation amount of the filter 14 is estimated from the time elapsed since the previous regeneration of the collection ability of the filter 14, the operating state of the internal combustion engine 1 during that time, and the like. Further, the PM accumulation amount may be estimated from the exhaust pressure difference between the upstream side and the downstream side of the filter 14. If it is determined that the PM deposition amount exceeds the predetermined deposition amount S1, the process proceeds to S102. If it is determined that the PM deposition amount does not exceed the predetermined deposition amount S1, the determination of S101 is performed again.

  In S102, the first temperature increase control described above is performed. That is, the opening degree of the intake throttle valve 10 is set to the throttle side opening degree, and the opening degree of the exhaust throttle valve 17 is set to the first temperature increase opening degree. In the present embodiment, the throttle-side opening is an opening at which the opening is 10%, and the opening at the time of the first temperature increase is an opening at which the opening is 10%. Thus, the timing when the opening degree of the intake throttle valve 10 and the exhaust throttle valve 17 is set is t0 in FIG.

  In this way, the temperature of the filter 14 increases as shown in FIG. 8 by adjusting the intake flow rate and the exhaust flow rate. Further, when the first temperature raising control is being performed, as the fuel injection from the fuel injection valve 3, as shown in FIG. 2 (a), three types of pre-injection, main injection, and post-injection are performed. When the process of S102 ends, the process proceeds to S103.

  In S103, it is determined whether or not the incoming gas temperature, which is the exhaust temperature flowing into the filter 14, exceeds the reference temperature α. The inlet gas temperature is detected by the exhaust temperature sensor 27. The reference temperature α is a reference value for determining the transition from the first temperature increase control to the second temperature increase control. If it is determined that the incoming gas temperature exceeds the reference temperature α, the process proceeds to S104. If it is determined that the incoming gas temperature does not exceed the reference temperature α, the determination in S103 is performed again.

  In S104, the above-described second temperature increase control is performed in place of the first temperature increase control performed in S102. That is, as shown in FIG. 2B, the injection timings of the pre-injection, main injection, and post-injection are shifted to the retard side, and the post-injection is divided into the first post-injection and the second post-injection.

  The timing at which the second temperature raising control is started is t1 in FIG. The filter temperature rises again at time t1. In the present embodiment, the injection amount in the post injection (inja1 and inja2) is gradually increased as time elapses after the second temperature increase control is started. This promotes an increase in exhaust temperature. When the process of S104 ends, the process proceeds to S105.

  In S105, it is determined whether or not the temperature of the filter 14 exceeds the reference temperature β. The temperature of the filter 14 is estimated from an exhaust temperature sensor 27, an exhaust temperature sensor provided on the downstream side of the filter 14 (not shown), and the like. Here, the reference temperature β is a reference value for determining the transition from the second temperature increase control to the third temperature increase control, and the NOx catalyst having an oxidation function carried by the filter 14 is in an active state. It is the temperature of the filter which shows that. If it is determined that the filter temperature exceeds the reference temperature β, the process proceeds to S106, and if it is determined that the filter temperature does not exceed the reference temperature β, the determination in S105 is performed again.

  In S106, the opening degree of the exhaust throttle valve 17 is set to the second temperature raising opening degree in the third temperature raising control. In the present embodiment, the opening during the second temperature increase is an opening at which the opening is 50%. The timing at which the opening of the exhaust throttle valve 17 is set to the second temperature elevation opening is t2 in FIG. When the opening of the exhaust throttle valve 17 is opened from the first temperature increase opening to the second temperature increase opening, the back pressure is slightly reduced. Therefore, during the period from time t2 to time t3 in FIG. 8, the amount of fuel injected by the post-injection is not increased but maintained at a constant amount. The time t3 is a timing at which the process of S107 described later is performed. When the process of S106 ends, the process proceeds to S107.

  In S107, the opening degree of the intake throttle valve 10 is set to the opening side opening degree in the third temperature raising control. In the present embodiment, the opening side opening is an opening at which the opening is 100% (fully open). The timing at which the opening of the intake throttle valve 10 is set to the opening side opening is t3 in FIG. When the opening degree of the intake throttle valve 10 is set to the opening side opening degree, the back pressure that has decreased due to the change in the opening degree of the exhaust throttle valve 17 in S106 increases, and the first temperature increase control and the second temperature increase control are performed. It becomes the same level as the back pressure in the closed period (period from time t0 to time t2). Further, after the back pressure rises, the fuel injection amount of the post-injection is increased again with the passage of time. When the fuel injection amount of the post-injection is increased to a necessary and sufficient amount for increasing the exhaust gas temperature, the fuel injection amount is maintained thereafter. When the process of S107 ends, the process proceeds to S108.

  In S108, it is determined whether or not the PM accumulation amount of the filter 14 is smaller than a predetermined accumulation amount S0. The predetermined accumulation amount S0 is a threshold value for determining whether or not to stop the temperature increase of the filter 14 by the third temperature increase control. Accordingly, when it is determined that the PM accumulation amount is smaller than the predetermined accumulation amount S0, the third temperature increase control is stopped and the present control is terminated. When the third temperature rise control is stopped, the fuel injection by the fuel injection valve 3 and the opening of the intake throttle valve 10 are appropriately set according to the operating state of the internal combustion engine 1, such as the engine load and the engine speed. Controlled. Further, the third temperature rise control in which the PM accumulation amount is determined to be equal to or greater than the predetermined accumulation amount S0 is continued, and the PM collected by the filter 14 is removed by oxidation.

  According to this control, the temperature of the filter 14 is increased through the first temperature increase control, the second temperature increase control, and the third temperature increase control, and the collected PM is oxidized and removed. In particular, the third temperature increase control increases the exhaust flow rate through the filter 14 while keeping the back pressure relatively high, thereby increasing the heat propagation speed in the filter 14, thereby removing the collected PM by oxidation. It is possible to carry out immediately without any unburned residue.

  A second embodiment of the filter temperature raising control for removing PM collected by the filter 14 will be described with reference to FIGS. FIG. 9 shows a flowchart regarding the filter temperature increase control using the first temperature increase control, the second temperature increase control, and the third temperature increase control described above. FIG. 10 shows the transition of the filter temperature (shown in FIG. 10A) and the transition of the opening degree of the exhaust throttle valve 17 (shown in FIG. 10B) when the filter temperature increase control of FIG. 9 is performed. ), Changes in the opening of the intake throttle valve 10 (shown in FIG. 10C), changes in the post-injection amount (shown in FIG. 10D), changes in the back pressure (shown in FIG. 10E). Respectively). This filter temperature increase control is performed by the ECU 20. The filter temperature raising control will be described below.

  In the filter temperature increase control shown in FIG. 9, the same reference numerals are assigned to the same processes as those in the filter temperature increase control shown in FIG. 7, and detailed description thereof is omitted. In this filter temperature increase control, if it is determined in S105 that the temperature of the filter 14 exceeds the reference temperature β, the process proceeds to S201. Moreover, about the time t4 and t5 shown in FIG. 10, it is synonymous with t0 and t1 shown in FIG.

  In S201, the above-described third temperature increase control is performed. That is, the opening degree of the intake throttle valve 10 is linearly changed from the throttle side opening degree (10%) to the opening side opening degree (100%), and at the same time, the opening degree of the exhaust throttle valve 17 is opened at the first temperature rise. The angle is changed linearly from the degree (10%) toward the second temperature elevation opening (50%). As shown in FIG. 10, at the time t6, the opening degree of the intake throttle valve 10 and the exhaust throttle valve 17 is linearly changed by the time t7.

  Thus, by controlling the opening degree of the intake throttle valve 10 and the exhaust throttle valve 17 in the third temperature rise control, it is possible to avoid the back pressure from fluctuating during the third temperature rise control. When the process of S201 ends, the process proceeds to S108.

  According to this control, the temperature of the filter 14 is increased through the first temperature increase control, the second temperature increase control, and the third temperature increase control, and the collected PM is oxidized and removed. In particular, the third temperature increase control increases the exhaust flow rate through the filter 14 while keeping the back pressure relatively high, thereby increasing the heat propagation speed in the filter 14, thereby removing the collected PM by oxidation. It is possible to carry out immediately without any unburned residue.

  A third embodiment of the filter temperature raising control for removing oxidation of PM collected by the filter 14 will be described with reference to FIGS. 11 and 12. In FIG. 11, the flowchart regarding the filter temperature rising control using the above-mentioned 1st temperature rising control, 2nd temperature rising control, and 3rd temperature rising control is shown. 12 shows the transition of the filter temperature (shown in FIG. 12A) and the transition of the opening degree of the exhaust throttle valve 17 (shown in FIG. 12B) when the filter temperature increase control of FIG. 11 is performed. ), The change in the opening of the intake throttle valve 10 (shown in FIG. 12C), the change in the post-injection amount (shown in FIG. 12D), and the change in the back pressure (shown in FIG. 12E). ) And transition of the drive signal of the auxiliary machine 31 (shown in FIG. 12 (f)). This filter temperature increase control is performed by the ECU 20. The filter temperature raising control will be described below.

  In the filter temperature increase control shown in FIG. 11, the same reference numerals are assigned to the same processes as those in the filter temperature increase control shown in FIG. 7, and the detailed description thereof is omitted. In this filter temperature increase control, if it is determined in S105 that the temperature of the filter 14 exceeds the reference temperature β, the process proceeds to S301. Moreover, about the time t8 and t9 shown in FIG. 12, it is synonymous with t0 and t1 shown in FIG.

  The above-described third temperature increase control is performed mainly at S301 and S305 described later. First, in S301, the opening degree of the intake throttle valve 10 is fully opened (100%), and at the same time, the opening degree of the exhaust throttle valve 17 is fully opened (100%). The timing at which the opening degree is controlled is time t10 in FIG. In this way, the exhaust flow rate flowing into the filter 14 is first increased to increase the heat propagation speed in the filter 14. However, since the opening of the exhaust throttle valve 17 is fully open (100%), the back pressure is greatly reduced and the exhaust temperature is lowered. Therefore, when the processing of S301 ends, the process proceeds to S302.

In S302, the auxiliary machine 31 is driven. In this embodiment, the timing at which the auxiliary machine 31 is driven is the above-described time t10. Since power stored in the battery 30 is consumed by driving the auxiliary machine 31, generation of power is started by the engine output of the internal combustion engine 1. As a result, the engine load of the internal combustion engine 1 increases, and the exhaust temperature is raised. When the process of S302 ends, the process proceeds to S303.

  In S303, the fuel injection amount by the main injection is adjusted to cope with the engine load increased by driving the auxiliary machinery. When the process of S303 ends, the process proceeds to S304.

  In S304, it is determined whether or not the temperature of the filter 14 exceeds the reference temperature γ. Here, the reference temperature γ is a reference value for determining that the exhaust throttle valve 17 that is fully open is changed to the second temperature increase opening (50%), and the exhaust flow rate to the filter 14 increases. As the heat propagation speed increases, the temperature of the filter 14 is increased, but this is also a reference value for detecting a state in which the temperature increase is slow. That is, the reference temperature γ is a reference value indicating that the temperature of the filter 14 has not reached a temperature at which PM can be efficiently oxidized and removed. If it is determined that the filter temperature exceeds the reference temperature γ, the process proceeds to S305. If it is determined that the filter temperature does not exceed the reference temperature γ, the determination in S304 is performed again.

  In S305, the opening degree of the exhaust throttle valve 17 is set to the second heating time opening degree (50%). The timing for changing the opening of the exhaust throttle valve 17 is time t11 in FIG. As a result, the back pressure rises and the exhaust temperature rises. When the process of S305 ends, the process proceeds to S306.

  In S306, in the case where the fuel injection amount by the post-injection is excessively large considering that the exhaust temperature has increased by setting the opening of the exhaust throttle valve 17 to the second temperature increase opening (50%) in S305. By reducing the fuel injection amount, the temperature of the filter 14 is prevented from excessively rising. When the process of S306 ends, the process proceeds to S108.

  According to this control, the temperature of the filter 14 is increased through the first temperature increase control, the second temperature increase control, and the third temperature increase control, and the collected PM is oxidized and removed. In particular, by the third temperature rise control, first, the exhaust flow rate through the filter 14 is increased to increase the heat propagation speed in the filter 14, and then the back pressure is set to a relatively high state, thereby oxidizing the collected PM. Removal can be performed immediately without burning.

  A fourth embodiment of the filter temperature rise control for removing the oxidized PM collected by the filter 14 will be described with reference to FIGS. 13 and 14. FIG. 13 shows a flowchart relating to the filter temperature increase control using the above-described first temperature increase control, second temperature increase control, and third temperature increase control. FIG. 14 shows the transition of the filter temperature (shown in FIG. 14A) and the transition of the opening of the exhaust throttle valve 17 (shown in FIG. 14B) when the filter temperature increase control of FIG. 13 is performed. ), The change in the opening of the intake throttle valve 10 (shown in FIG. 14C), the change in the post-injection amount (shown in FIG. 14D), and the change in the back pressure (shown in FIG. 14E). ), And the transition of the drive signal of the auxiliary machine 31 (shown in FIG. 14F). This filter temperature increase control is performed by the ECU 20. The filter temperature raising control will be described below.

  In the filter temperature increase control shown in FIG. 13, the same reference numerals are assigned to the same processes as those in the filter temperature increase control shown in FIG. 11, and detailed descriptions thereof are omitted. In this filter temperature increase control, process S401 is performed instead of process S305 in the filter temperature increase control shown in FIG.

In S401, from the time t11 to t12, the opening degree of the exhaust throttle valve 17 is linearly changed from the fully open (100%) to the second heating time opening degree (50%). That is, as in S305 in the filter temperature increase control shown in FIG.
0%), gradually change to the desired opening. Thereby, since the back pressure also gradually increases, it is possible to avoid a local temperature increase of the filter 14 due to a sudden increase in the back pressure. When the process of S401 ends, the process proceeds to S306.

  In S306, as described above, the fuel injection amount by the post-injection is adjusted according to the increase in the back pressure. Here, since the opening degree of the exhaust throttle valve 17 is gradually reduced from the timing t11 to the timing t12, the fuel injection amount by the post-injection is also linked to the change in the opening degree of the exhaust throttle valve 17, and the timing t11. From time to time t12.

  According to this control, the temperature of the filter 14 is increased through the first temperature increase control, the second temperature increase control, and the third temperature increase control, and the collected PM is oxidized and removed. In particular, by the third temperature rise control, first, the exhaust flow rate through the filter 14 is increased to increase the heat propagation speed in the filter 14, and then the back pressure is set to a relatively high state, thereby oxidizing the collected PM. The removal can be performed immediately without any burning residue.

It is a figure showing the schematic structure of the compression ignition internal combustion engine to which this invention is applied, and its control system. The state of the opening degree of the fuel injection and the intake throttle valve in the first temperature increase control, the second temperature increase control, and the third temperature increase control performed in the exhaust gas purification apparatus for the compression ignition internal combustion engine according to the embodiment of the present invention is shown. FIG. It is a figure showing transition of exhaust gas temperature and filter temperature when temperature rise of a filter is performed in an exhaust emission control device of a compression ignition internal combustion engine concerning an example of the present invention. It is a figure showing the schematic structure of the filter in the exhaust emission control device of the compression ignition internal combustion engine which concerns on the Example of this invention. In the exhaust gas purification apparatus for a compression ignition internal combustion engine according to the embodiment of the present invention, the first diagram showing the transition of the filter temperature when the third temperature increase control is performed and when the third temperature increase control is not performed It is. FIG. 2 is a second diagram showing the transition of the filter temperature when the third temperature increase control is performed and when the third temperature increase control is not performed in the exhaust gas purification apparatus for a compression ignition internal combustion engine according to the embodiment of the present invention. It is. It is a flowchart of the filter temperature increase control performed in the exhaust emission control device of the compression ignition internal combustion engine according to the first embodiment of the present invention. It is a figure which shows the fluctuation | variation of filter temperature, the opening degree of an exhaust throttle valve, the opening degree of an intake throttle valve, the fuel injection quantity by back injection, and a back pressure at the time of filter temperature rising control shown in FIG. It is a flowchart of the filter temperature rising control performed in the exhaust gas purification apparatus of the compression ignition internal combustion engine which concerns on Example 2 of this invention. FIG. 10 is a diagram showing fluctuations in filter temperature, exhaust throttle valve opening, intake throttle valve opening, fuel injection amount due to post-injection, and back pressure when the filter temperature raising control shown in FIG. 9 is performed. It is a flowchart of the filter temperature rising control performed in the exhaust gas purification apparatus of the compression ignition internal combustion engine which concerns on Example 3 of this invention. FIG. 11 shows the filter temperature, the exhaust throttle valve opening, the intake throttle valve opening, the fuel injection amount due to post-injection, the fluctuation of the back pressure, and the driving state of the auxiliary machine when the filter temperature raising control shown in FIG. 11 is performed. FIG. It is a flowchart of the filter temperature rising control performed in the exhaust gas purification apparatus of the compression ignition internal combustion engine which concerns on Example 4 of this invention. FIG. 13 shows the filter temperature, the exhaust throttle valve opening, the intake throttle valve opening, the fuel injection amount due to the post-injection, the fluctuation of the back pressure, and the driving state of the auxiliary machine when the filter temperature raising control shown in FIG. 13 is performed. FIG.

Explanation of symbols

1. Compression compression internal combustion engine (internal combustion engine)
3 ... Fuel injection valve 10 ... Air intake throttle valve 11 ... Air intake throttle actuator 13 ... Exhaust pipe 14 ... Filter 16 ... Supercharger 17 ...・ Exhaust throttle valve 18 ... Exhaust throttle actuator 20 ... ECU
27 ... Exhaust temperature sensor 31 ... Auxiliary equipment

Claims (4)

An intake throttle valve for adjusting the intake flow rate of the intake passage of the compression ignition internal combustion engine;
An exhaust throttle valve for adjusting the exhaust flow rate of the exhaust passage of the compression ignition internal combustion engine;
A filter carrying a catalyst having an oxidation function and collecting particulate matter in the exhaust;
Intake throttle valve opening control means for controlling the opening of the intake throttle valve;
Exhaust throttle valve opening control means for controlling the opening of the exhaust throttle valve;
Fuel injection conditions for main injection at a timing near compression top dead center, and fuel injection conditions for post-injection after the main injection in which at least part of the fuel is combusted by combustion of the injected fuel by the main injection Fuel injection control means for controlling
The intake throttle valve opening control means sets the intake throttle valve opening to the throttle side opening, and the exhaust throttle valve opening control means sets the exhaust throttle valve opening to the first temperature increase opening. A first filter temperature raising means for raising the temperature of the filter;
When the temperature of the filter is raised by the first filter temperature raising means, the fuel injection control means controls the fuel injection timings of the main injection and the post-injection to a retarded state, and then the intake throttle The opening degree of the intake throttle valve is changed from the throttle side opening degree to the opening side opening degree by the valve opening degree control means, and the opening degree of the exhaust throttle valve is changed by the exhaust throttle valve opening degree control means when the first temperature rises. A second filter temperature raising means for raising the temperature of the filter by setting a second temperature raising opening degree that is open from the opening degree;
An exhaust emission control device for a compression ignition internal combustion engine. A filter temperature estimating means for estimating or detecting the temperature of the filter;
The second filter temperature raising means is configured to control the filter temperature estimated or detected by the filter temperature estimating means after the fuel injection timings of the main injection and the post-injection are controlled to be retarded. The opening degree of the intake throttle valve is set to the opening side opening degree when the temperature is higher than the temperature, and the opening degree of the exhaust throttle valve is set to the second temperature increase opening degree. Exhaust gas purification device for compression ignition internal combustion engine.   The second filter temperature raising means is configured such that after the exhaust throttle valve opening degree is set to the second temperature raising opening degree by the exhaust throttle valve opening degree control means, the intake throttle valve opening degree control means causes the intake The exhaust purification device of a compression ignition internal combustion engine according to claim 1 or 2, wherein the opening of the throttle valve is set to the opening side opening. An intake throttle valve that adjusts the intake flow rate of the intake passage of the compression ignition internal combustion engine, an exhaust throttle valve that adjusts the exhaust flow rate of the exhaust passage of the compression ignition internal combustion engine, and a catalyst having an oxidation function are supported and particles in the exhaust An exhaust gas purification method for a compression ignition internal combustion engine comprising: a filter that collects particulate matter;
A first filter temperature raising step for raising the temperature of the filter by setting the opening degree of the intake throttle valve as a throttle side opening degree and setting the opening degree of the exhaust throttle valve as a first temperature elevation opening degree;
Reject the fuel injection timing of each of the main injection and the fuel injection after the main injection in the vicinity of the compression top dead center, in which at least part of the fuel is combusted by the combustion of the injected fuel by the main injection And when the temperature of the filter is higher than a predetermined temperature, the opening of the intake throttle valve is changed from the throttle-side opening to the opening-side opening and the exhaust throttle valve is opened. A second temperature raising step of raising the temperature of the filter by setting the second temperature raising opening that is open from the first temperature raising opening,
An exhaust purification method for a compression ignition internal combustion engine comprising:

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