JP2016121625A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine which can efficiently remove a sulfur compound from a deteriorated catalyst while suppressing the generation of white smoke.SOLUTION: A control device of an internal combustion engine comprises: acquisition means which acquires a terminal history of a catalyst arranged in an exhaust passage; temperature-rise control means which performs temperature control for raising a temperature of the catalyst up to a prescribed temperature so that a sulfur compound in the catalyst is discharged from the catalyst without making the sulfur compound generate white smoke; and temperature-rise speed change means which largely raises a temperature-rise speed of the catalyst in a temperature range of at least a part within the temperature range up to the prescribed temperature by the temperature rise control of the temperature-rise control means as a deterioration degree of the catalyst which is estimated from the thermal history acquired by the acquisition means is large, and also as the temperature of the catalyst is high.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device for an internal combustion engine.

In order to purify exhaust gas of a diesel engine, a DOC (Diesel Oxidation Catalyst) and a DPF (Diesel Particulate Filter) are provided in this order from the upstream side in the exhaust passage of the diesel engine. The DPF is a filter for collecting particulate matter (PM) in exhaust gas. DOC is a catalyst that oxidizes hydrocarbons and carbon monoxide in exhaust gas to convert them into water and carbon dioxide, and converts nitrogen monoxide in exhaust gas into nitrogen dioxide for oxidizing PM. That is.

  In an internal combustion engine system in which DOC and DPF are provided in the exhaust passage, sulfur compounds (SOx) that reduce the performance of the DOC may accumulate in the DOC. In addition, a large amount of PM accumulates in the DPF, and the PM collection ability of the DPF may decrease. Therefore, in an internal combustion engine system in which DOC and DPF are provided in the exhaust passage, normally, when the PM accumulation amount in the DPF exceeds a predetermined amount, the DPF and DOC are heated by post injection or the like to increase the temperature in the DOC. The sulfur compound is discharged and the PM in the DPF is combusted.

However, when the heating rate of DPF and DOC during the above treatment is high, high-concentration sulfur compound (SO ₃ ) released from DOC reacts with moisture, and white smoke (sulfate white smoke) that adversely affects the human body May be released into the atmosphere. For this reason, the temperature of the catalyst is increased at a low speed when the catalyst (DPF and DOC) is regenerated. Further, at the time of regeneration of the catalyst, the temperature of the catalyst is maintained at a predetermined temperature (500 ° C. to 550 ° C.) for a time corresponding to the amount of sulfur compound accumulated in the catalyst, and then the temperature for burning PM (for example, It is also proposed to increase the temperature to 700 ° C. (hereinafter referred to as the regeneration temperature) (see, for example, Patent Document 1).

JP 2013-029038 A JP 2009-228618 A JP 2002-263493 A JP 2012-021411 A

Toyota Central R & D Review Vol. 27, no. 3, P.I. 43-53 (19922.9)

  If the temperature of the catalyst is raised at a low speed, the sulfur compound adsorbed in the catalyst can be discharged from the catalyst without white smoke. However, the catalyst is thermally deteriorated (see Non-Patent Document 1). When the catalyst is thermally deteriorated, the amount of sulfur compounds adsorbed on the catalyst is reduced. Therefore, the temperature increase rate of the catalyst is determined without considering the state of the catalyst (degradation degree). In addition, there is a risk that the fuel is wasted.

  Therefore, an object of the present invention is to provide an internal combustion engine that can efficiently remove sulfur compounds from a deteriorated catalyst while suppressing the generation of white smoke (in a form in which useless fuel is not used for raising the temperature of the catalyst). It is to provide a control device.

  In order to solve the above-described problems, an internal combustion engine control apparatus according to the present invention has an acquisition means for acquiring a thermal history of a catalyst disposed in an exhaust passage of an internal combustion engine, and a sulfur compound in the catalyst is white smoke. Temperature increase control execution means for executing temperature increase control for increasing the temperature of the catalyst to a predetermined temperature so that the catalyst is discharged without being discharged, and the temperature increase control by the temperature increase control execution means to the predetermined temperature. As the degree of deterioration of the catalyst estimated from the thermal history acquired by the acquisition means is higher, the temperature of the catalyst is higher in at least a part of the temperature range. The temperature increase rate changing means for greatly increasing the temperature is provided.

  That is, the sulfur compound is adsorbed on the catalyst in a form in which the adsorption (bonding) energy is distributed, that is, in a form in which the desorption temperature from the catalyst is distributed. Further, when the catalyst deteriorates, the adsorption amount of the sulfur compound decreases, but the decrease rate of the adsorption amount due to deterioration tends to increase as the desorption temperature (adsorption energy) increases. Therefore, in the temperature rise pattern (temperature rise control executed by the temperature rise control execution means) in which the sulfur compound in the catalyst that has not deteriorated can be discharged from the catalyst without white smoke, the catalyst estimated from the heat history is used. There is room for increasing the rate of temperature increase as the degree of deterioration increases and the temperature of the catalyst increases. If the rate of temperature increase is increased, the amount of fuel consumed for increasing the temperature of the catalyst can be reduced. Therefore, in the present invention, by providing the temperature increase rate changing means, the temperature increase pattern of the catalyst (content of the temperature increase control executed by the temperature increase control execution means) according to the degree of deterioration estimated from the catalyst thermal history. Is changed.

  The control apparatus for an internal combustion engine of the present invention can be realized in various forms. For example, as the temperature increase control execution means of the control device for an internal combustion engine of the present invention, means for executing temperature increase control without using the estimation result of the amount of sulfur compound adsorbed on the catalyst can be employed. Further, the control device for an internal combustion engine according to the present invention may be configured so that “in the sulfur compound adsorbed on the catalyst for each of a plurality of temperature sections obtained by dividing a temperature range up to the maximum temperature of the catalyst to be reached by the temperature increase control”. Management means for estimating and managing the amount of sulfur compounds released from the catalyst during the temperature rise of the catalyst to the maximum temperature, and the temperature rise control execution means The temperature increase control to be executed is performed at a speed at which the amount of the sulfur compound managed by the management means for each temperature section is discharged from the catalyst without white smoke. The temperature rise rate changing means is configured to control the degree of deterioration of the catalyst estimated from the thermal history to determine the amount of the sulfur compound related to each temperature category managed by the estimating means. Kinahodo, and, as the temperature indicator is high, largely by reducing the a means for changing the Atsushi Nobori rate of the catalyst by temperature increase control "may be previously implemented as an apparatus.

  According to the present invention, it is possible to efficiently remove sulfur compounds from a deteriorated catalyst while suppressing the generation of white smoke (in a form in which useless fuel is not used for raising the temperature of the catalyst).

FIG. 1 is a schematic configuration diagram of an internal combustion engine system to which an internal combustion engine control apparatus according to an embodiment of the present invention is applied. FIG. 2 is a flowchart of an exhaust purification unit management process executed by the ECU in the internal combustion engine system. FIG. 3 is a graph for explaining temperature (temperature division) dependence of the decrease rate of the S adsorption amount due to catalyst deterioration. FIG. 4 is an explanatory diagram of the adhesion state of the sulfur compound in the catalyst. FIG. 5 is a diagram for explaining functions of the control device for the internal combustion engine according to the embodiment. FIG. 6 is a diagram for explaining a modification of the control device for the internal combustion engine according to the embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a schematic configuration of an internal combustion engine system to which an internal combustion engine control apparatus according to an embodiment of the present invention is applied.

  This internal combustion engine system is a system mounted on a vehicle. As shown in FIG. 1, the internal combustion engine system includes an internal combustion engine 10 and an ECU (Electronic Control Unit) 40. The internal combustion engine system is a system in which a part of the ECU 40 (a part that executes an exhaust purification unit management process described later) substantially corresponds to the control device for the internal combustion engine according to the present embodiment.

  The internal combustion engine 10 is a diesel engine having four cylinders 11. The internal combustion engine 10 is provided with a common rail 13 for accumulating high-pressure fuel sent from a supply pump and four injectors 12 for injecting high-pressure fuel in the common rail 13 into each cylinder 11. . The internal combustion engine 10 is also provided with a water temperature sensor for measuring the temperature of the cooling water circulating in the internal combustion engine 10 and a crank position sensor for detecting the number of rotations (posture) of the crankshaft.

  Each cylinder 11 (combustion chamber of each cylinder 11) of the internal combustion engine 10 is connected to an intake passage 15 via an intake manifold 14. Each cylinder 11 is connected to an exhaust passage 22 via an exhaust manifold 21, and the exhaust manifold 21 is provided with a fuel addition device 25 for adding fuel to the exhaust gas flowing through the exhaust manifold 21. It has been.

A turbine 17 b of the turbocharger 17 is provided in the middle of the exhaust passage 22. An exhaust purification device 30 in which a DPF (Diesel Particulate Filter) 32 is disposed downstream of the DOC (Diesel Oxidation Catalyst) 31 is provided in a portion of the exhaust passage 22 on the downstream side of the turbine 17b. The exhaust purification device 30 includes a temperature sensor 35 for measuring the temperature of the exhaust purification device 30, a pressure difference sensor 36 for measuring a pressure difference before and after the DPF 32 (hereinafter referred to as a DPF differential pressure), and Is provided.

  In the middle of the intake passage 15, a compressor 17a of the turbocharger 17 and an intercooler 16 for cooling the compressed air from the compressor 17a are provided.

  An air flow meter 18 for measuring the flow rate of intake air (fresh air) is provided in a portion of the intake passage 15 upstream of the compressor 17a. An intake throttle valve 19 for adjusting the flow rate of intake air is provided in a portion of the intake passage 15 downstream of the intercooler 16.

An EGR device is provided between the exhaust manifold 21 and the intake manifold 14 for returning a part of the exhaust gas flowing in the exhaust manifold 21 (hereinafter referred to as EGR (Exhaust Gas Recirculation) gas) to the intake manifold 14. ing. This EGR device includes an EGR passage 20a connecting the exhaust manifold 21 and the intake manifold 14, an EGR valve 20b for adjusting the amount of EGR gas flowing in the EGR passage 20a, and an EGR cooler 20c for cooling the EGR gas. It is comprised by.

The ECU 40 is a unit that integrally controls each part of the internal combustion engine system (the intake throttle valve 19, the injector 12, the fuel addition device 25, etc.). Various sensors described above are electrically connected to the ECU 40. The ECU 40 is also electrically connected to an accelerator opening sensor 28, an ignition switch, and the like. The ECU 40 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. A program (firmware) executed by the CPU is stored in the ROM of the ECU 40. Yes.

  Hereinafter, the function of the ECU 40 will be described with a focus on the control content related to the exhaust purification unit 30.

  When the internal combustion engine 10 is started, the ECU 40 is in a state of executing the exhaust purification unit management process of the procedure shown in FIG. 2 while executing the control process related to the internal combustion engine 10.

  The loop processing of steps S101 to S103 of this exhaust purification unit management processing is performed for each of the first to Nth temperature segments (N ≧ 2) so that the values represent the current state until the catalyst regeneration processing start condition is satisfied. This is a process of periodically updating the adsorption amount.

  Here, the catalyst regeneration process start condition is a catalyst regeneration process start condition that is the process of steps S104 to S109. The catalyst regeneration process start condition is a condition such as “DPF differential pressure (measurement result of differential pressure by pressure difference sensor 36) is a predetermined value or more”, or “PM in DPF 32 estimated from operation history of internal combustion engine 10”. It is possible to use a condition such as “the deposition amount is greater than or equal to a predetermined amount”. Further, as the catalyst regeneration process start condition, a condition such as “the estimated amount of the sulfur compound in the exhaust purification unit 30 is equal to or larger than a predetermined amount” or “the estimated amount of the sulfur compound in the exhaust purification unit 30 is equal to or larger than the predetermined amount. Alternatively, a condition such that the DPF differential pressure is a predetermined value or more can be used.

  The first to Nth temperature segments are up to the S removal completion temperature (for example, 600 ° C.) determined as the temperature of the exhaust purification unit 30 at which the sulfur compound in the exhaust purification unit 30 (mainly DOC31) is completely removed. Is a temperature section obtained by dividing the temperature range into N. In the following description, it is assumed that the Nth temperature section is the highest temperature section. The number of temperature segments (value of N) is not particularly limited, but is usually a value of about 5 to 10. Further, the width of each temperature section (temperature difference between the boundary temperatures of each temperature section) may or may not be the same.

  The amount of S adsorption related to the kth temperature section (k = 1 to N) is the amount released from the exhaust purification section 30 (DOC31) in the kth temperature section when the temperature of the exhaust purification section 30 is raised to the S removal completion temperature. This is an estimated value (the initial value is “0”) of the amount of sulfur compound to be produced.

  Hereinafter, the contents of the loop processing in steps S101 to S103 will be described more specifically.

  In step S101, the ECU 40 specifies the purification unit temperature, the inflow S amount, and the heat history. Here, the purification unit temperature is the temperature of the exhaust purification unit 30 (in this embodiment, the temperature measured by the temperature sensor 35). Further, the inflow S amount flows into the exhaust purification unit 30 from the time when the processing of the previous step S101 is performed (or when the exhaust purification unit management processing is started) to the time of the execution of the current processing of step S101. It is the amount of sulfur compounds. As the process for specifying the inflow S amount, a process for calculating the inflow S amount from the operation state of the internal combustion engine 10 (fuel injection amount to each cylinder 11 and the like) and the sulfur amount contained in the fuel is performed.

  The thermal history is information managed by the ECU 40 as an indicator of the degree of deterioration of the DOC 31. The heat history may be information that can be used to estimate the degree of deterioration of the DOC 31. Therefore, as the heat history, an integrated value of the time during which the purification unit temperature is equal to or higher than a predetermined temperature (for example, 500 ° C.), the number of times of performing the catalyst regeneration process (the processes of steps S104 to S109), and the like can be used. . Further, the degree of deterioration of the DOC 31 may be a value that increases as the DOC 31 deteriorates. Therefore, the thermal history itself may be used as the degree of deterioration.

  ECU40 which finished the process of step S101 performs the following processes in the following step S102. In the following description, the m-th temperature segment (1 ≦ m ≦ N) is a temperature segment including the purification unit temperature at that time. Moreover, the period t is an execution period of the loop processing in steps S101 to S103.

  In step S102, the ECU 40 desorbs the S adsorption amount for each of the p-th temperature segments (p = 1 to m) from the first temperature segment to the m-th temperature segment by the desorption amount (p, m). Perform quantity reflection processing.

  The desorption amount (p, m) is desorbed in the “pth temperature section released from the exhaust purification section 30 (DOC31) during the period t under the condition that the purification section temperature is in the mth temperature section. This is the amount of the sulfur compound adsorbed in the DOC 31 in the state. As the desorption amount (p, m), a value predetermined by various experiments or a value obtained from a theoretical formula can be used. In the desorption amount reflecting process, the ECU 40 changes the S adsorption amount to “0” when the S adsorption amount decreased by the desorption amount (p, m) becomes a negative value.

  In step S102, the ECU 40 determines the S adsorption amount related to each pth temperature segment from the (m + 1) th temperature segment to the Nth temperature segment as "distribution rate (p, m), inflow S amount, adsorption amount decrease rate (p, The adsorption amount reflecting process for increasing the degree of deterioration) ”is also performed.

  The distribution rate (p, m) is depleted in the p-th temperature section when a unit amount of sulfur compound flows into the exhaust purification unit 30 that has not deteriorated and the temperature is in the m-th temperature section for the period t. It is the amount of sulfur compound adsorbed in the DOC 31 in a separated state. As the distribution rate (p, m), a value predetermined by various experiments or a value obtained from a theoretical formula can be used.

  The adsorption amount decrease rate (p, degree of deterioration) is the DOC31 estimated from the heat history to the sulfur compound adsorption amount (increase in S adsorption amount) calculated from the distribution rate (p, m) and the inflow S amount. This is a correction coefficient for performing correction according to the degree of deterioration.

  As shown in FIG. 3, the rate of decrease due to the deterioration of the DOC 31 in the S adsorption amount for each temperature segment increases as the temperature segment increases. Note that FIG. 3 shows the percentage ratio of the S adsorption amount for each temperature category (“inferior adsorption amount / new contact adsorption amount” × 100) for each temperature segment for the undegraded DOC 31 and the DOC 31 degraded to a certain level. It is the figure (graph) plotted with respect to the median temperature of a division.

  As the deterioration of the DOC 31 progresses, the rate of decrease of the S adsorption amount related to each temperature section due to the deterioration of the DOC 31 increases. Therefore, the adsorption amount reduction rate (p, the degree of deterioration) increases as p increases and the degree of deterioration increases. Further, the S adsorption amount calculated and managed by the ECU 40 becomes smaller as the temperature classification is higher and the deterioration degree is larger.

Here, the reason why the S adsorption amount at the present time (the execution time of the process of step S101) for each temperature category can be obtained by repeating the processes of steps S101 and S102 will be described.

  As schematically shown in FIG. 4, the binding (adsorption) energy of the sulfur compound adsorbed on the carrier (alumina in FIG. 4) in the exhaust purification unit 30 (DOC 31) is the distance from the carrier surface (the carrier surface and Depending on the number of sulfur compound layers present between the two.

  Therefore, when the temperature of the exhaust purification unit 30 reaches a certain temperature T, the sulfur compound adsorbed in the exhaust purification unit 30 in a state of being desorbed at a temperature equal to or lower than the temperature T is adsorbed to the exhaust purification unit 30. It is discharged from the exhaust purification unit 30 at a speed according to (adsorption energy). Further, the sulfur compound that has flowed into the exhaust purification unit 30 at the temperature T is adsorbed in the exhaust purification unit 30 in a state of being desorbed at a temperature exceeding the temperature T. However, when the DOC 31 is thermally deteriorated, the amount of sulfur compound adsorbed decreases (FIG. 3). Therefore, when a certain amount of sulfur compound flows in, the S adsorption amount for each temperature segment increases by “distribution rate (p, m), inflow S amount, adsorption amount decrease rate (p, deterioration degree)”. Become.

  Therefore, by repeating the process described above, it is possible to obtain the S adsorption amount at the present time (the time when the process of step S101 is executed) for each temperature category.

Returning to FIG. 2, the description of the exhaust gas purification unit management process will be continued.
When the catalyst regeneration process start condition is satisfied (step S103; YES), the ECU 40 starts the catalyst regeneration process (the processes of steps S104 to S108).

  The ECU 40 that has started the catalyst regeneration process first controls the fuel addition device 25 to increase the temperature of the exhaust purification unit 30 at a high speed to the lower limit temperature of the lowest temperature section where the S adsorption amount is equal to or greater than the specified amount. (Step S104) is performed. Here, the specified amount is a value set in advance as a lower limit value of the amount of S adsorption that can generate white smoke when the exhaust purification unit 30 is heated at a high speed (without limiting the rate of temperature increase). That is.

  In short, when the S adsorption amount for each temperature segment up to the (n-1) th temperature segment is less than the specified amount and the S adsorption amount for the nth temperature segment is equal to or greater than the specified amount, the lower limit temperature of the nth temperature segment Even if the temperature of the exhaust purification unit 30 is increased to a high speed, white smoke is not generated. And the fuel consumption amount decreases as the temperature raising rate of the exhaust purification unit 30 is faster. Therefore, when the catalyst regeneration process is started, the process described above is performed. Note that the process of step S104 may be a process of increasing the temperature of the exhaust purification unit 30 by adjusting the post injection amount by the injector 12.

  ECU40 which finished the process of step S104 is the temperature increase rate which can remove the sulfur compound of the quantity, without generating white smoke from S adsorption amount regarding the present temperature division (temperature division including the purification | cleaning part temperature at that time). Processing to determine (step S105) is performed. As the processing of this step, for example, the temperature increase rate associated with the S adsorption amount related to the current temperature segment is obtained from the temperature increase rate table related to the current temperature segment, which associates the temperature increase rate with various S adsorption amounts. A reading process is performed.

  The temperature increase rate table for associating various S adsorption amounts with the temperature increase rate may be detailed, but there is an error in the S adsorption amount that is an estimated value. Therefore, the temperature increase rate table may be a table in which points indicating the correspondence relationship between the S adsorption amount and the temperature increase rate obtained from some experimental results are connected with a straight line. Further, it is preferable that the time required for raising the purification section temperature to the S removal completion temperature is short. Accordingly, in the temperature increase rate table for each temperature category, a sulfur compound having a concentration close to the concentration that is equal to or less than the concentration that causes white smoke (for example, 80% of the concentration that causes white smoke) is released. It is preferable to set a temperature rate.

  The ECU 40 that has determined the temperature increase rate controls the fuel addition device 25 to increase the temperature of the exhaust purification unit 30 to the lower limit temperature of the next temperature segment (the upper limit temperature of the current temperature segment) at the determined temperature increase rate ( Step S106) is performed. The control performed during the processing of this step (hereinafter referred to as interval unit temperature increase control) is that “width of current temperature segment / time until interval unit temperature increase control is completed” is less than the determined temperature increase rate. As long as the control is, closed-loop control or open-loop control may be used. Further, the section-unit temperature increase control may be control for adjusting the post injection amount by the injector 12.

  After completing the process of step S106, the ECU 40 clears the S adsorption amount related to the current temperature class by “0” (step S107), and then determines whether or not the purification unit temperature has reached the S removal completion temperature (step S108). ).

  When the purification unit temperature has not reached the S removal completion temperature (step S108; NO), in other words, when the current temperature segment is not the Nth temperature segment (the highest temperature segment), the ECU 40 proceeds to step S105. Returning to, temperature increase control for the next temperature segment is performed.

  On the other hand, when the purification unit temperature reaches the S removal completion temperature while repeating the above processing (step S108; YES), the ECU 40 performs PM regeneration processing (step S109). During this PM regeneration process, the ECU 40 increases the purification unit temperature to the regeneration temperature (for example, 800 ° C.) and monitors whether the DPF differential pressure becomes equal to or higher than a predetermined regeneration completion differential pressure. Then, when the DPF differential pressure becomes equal to or higher than the regeneration completion differential pressure, the ECU 40 ends the PM regeneration process (step S109), updates the heat history (step S110), and then repeats the processes after step S101. Start.

  As described above, when the DOC 31 is deteriorated, the adsorption amount of the sulfur compound on the high temperature side is greatly reduced (see FIG. 3), but the control device for the internal combustion engine according to the present embodiment (a part of the ECU 40) In consideration of the degree of deterioration of the DOC 31 due to the history, the S adsorption amount for each temperature category is calculated. Therefore, the S adsorption amount for each temperature category calculated by the control device for the internal combustion engine according to the present embodiment is closer to the actual amount than the S adsorption amount calculated without considering the degree of deterioration of the DOC31. . And the control apparatus of the internal combustion engine which concerns on this embodiment raises the temperature of the exhaust gas purification part 30 in the said procedure based on the S adsorption amount regarding each calculated temperature division. Therefore, according to the control apparatus for an internal combustion engine according to the present embodiment, even when the DOC 31 is deteriorated, the removal of the sulfur compound from the DOC 31 is efficient (for increasing the temperature of the catalyst) while suppressing the generation of white smoke. In a way that wasteful fuel is not used).

  Specifically, when the exhaust purification unit 30 calculates the S adsorption amount for each temperature category without considering the deterioration of the DOC 31 and increases the temperature based on the calculation result, the temperature increase pattern (as indicated by the dotted line in FIG. Let us consider a case where the temperature is raised with “no correction of catalyst supplementary deterioration”) and the DOC 31 is in a deteriorated state.

  When the exhaust purification unit 30 is in the above state, the S adsorption amount for each temperature segment calculated without considering the deterioration of the DOC 31 is larger than the actual sulfur compound adsorption amount (see FIG. 3). Therefore, in this case, even if the temperature increase rate on the high temperature side is increased, white smoke is not generated, but the temperature on the high temperature side is increased at a low temperature increase rate.

On the other hand, the control device for an internal combustion engine according to the present embodiment calculates the S adsorption amount for each temperature segment in consideration of the degree of deterioration of the DOC 31 due to the thermal history, and raises the temperature of the exhaust purification unit 30 based on the calculation result. Therefore, according to the control apparatus for an internal combustion engine according to the present embodiment, when the exhaust purification unit 30 is in the above-described state, the exhaust purification unit 30 may cause the temperature increase pattern (“catalyst supplemental deterioration” as shown by a solid line in FIG. The temperature will be raised at “with correction”). As a result, it is possible to suppress the useless use of fuel for raising the temperature of the exhaust purification unit 30.

<Deformation>
The “control device for an internal combustion engine” (hereinafter also simply referred to as a control device) according to the above-described embodiment can be variously modified. For example, the above control can be applied to any internal combustion engine having a catalyst capable of adsorbing a sulfur compound in the exhaust passage. Therefore, the control device according to the embodiment can be modified into a control device for an internal combustion engine (gasoline engine, diesel engine) different from those described above in terms of the type and number of catalysts.

  In addition, the control device according to the embodiment can be modified to a device that changes the temperature rising pattern according to the degree of deterioration of the DOC 31 without using the S adsorption amount for each temperature section. However, in such a case, it is unclear how much the temperature increase rate on the high temperature side can be increased, and thus the amount of change in the temperature increase pattern is limited. Therefore, it is preferable that the temperature increase pattern is changed based on the calculation result of the S adsorption amount for each temperature category.

  The control apparatus which concerns on embodiment was an apparatus which raises the temperature increase rate in each temperature of a high temperature side (refer FIG. 5). However, even if only the temperature increase rate in a part of the temperature range up to the S removal completion temperature is increased, the amount of fuel used for increasing the temperature of the exhaust purification unit 30 decreases. Therefore, the control device according to the embodiment increases the rate of temperature increase in a part of the temperature range up to the S removal completion temperature as the degree of deterioration of the DOC 31 estimated from the thermal history increases and the temperature of the DOC 31 increases. The higher the value, the larger the device may be.

  Further, as already described, the section-unit temperature increase control performed at the time of the process of step S106 is that the “width of current temperature section / time until section-unit temperature increase control is completed” is equal to or less than the determined temperature increase rate. Any control can be used. Therefore, as shown in FIG. 6, the control device according to the embodiment can be modified to a device that raises the temperature of the purification unit stepwise.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 11 Cylinder 12 Injector 13 Common rail 14 Intake manifold 15 Intake passage 16 Intercooler 17 Turbocharger 17a Compressor 17b Turbine 18 Air flow meter 19 Intake throttle valve 20a EGR passage 20b EGR valve 20c EGR cooler 21 Exhaust manifold 2522 Exhaust manifold 2522 Device 28 Accelerator opening sensor 30 Exhaust gas purification unit 31 DOC
32 DPF
35 Temperature sensor 36 Pressure difference sensor 40 ECU

Claims (1)

Obtaining means for obtaining a thermal history of a catalyst disposed in an exhaust passage of the internal combustion engine;
Temperature increase control execution means for executing temperature increase control for increasing the temperature of the catalyst to a predetermined temperature so that the sulfur compound in the catalyst is discharged from the catalyst without white smoke;
The temperature increase rate of the catalyst in at least a part of the temperature range up to the predetermined temperature by the temperature increase control by the temperature increase control execution unit is estimated from the thermal history acquired by the acquisition unit. A temperature increase rate changing means for increasing the degree of deterioration of the catalyst as the degree of deterioration increases and as the temperature of the catalyst increases;
A control device for an internal combustion engine, comprising:

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