JP2009250047A - Temperature control device of exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably maintain the target temperature by restraining an overshoot to the target temperature, while enabling an early arrival at the target temperature of an exhaust emission control device, by taking into consideration a flow rate of exhaust gas, in a temperature control device for controlling the temperature of the exhaust emission control device via opening control of an exhaust throttle valve. <P>SOLUTION: This temperature control device has the exhaust throttle valve, a temperature detecting means for detecting the temperature of a catalyst device, an opening control means for controlling opening of the exhaust throttle valve, and an exhaust flow rate detecting means for detecting an exhaust flow rate Qe, and controls the temperature in the target temperature To of the catalyst device by controlling the opening of the exhaust throttle valve by the opening control means. The opening control means controls the exhaust throttle valve in required opening β by calculating the required opening β of the exhaust throttle valve based on a temperature difference ΔT being an absolute value of a difference between the target temperature To being the temperature when the catalyst device is put in an active state and the actual temperature T detected by the temperature detecting means and the exhaust flow rate Qe detected by the exhaust flow rate detecting means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a temperature control device for controlling an opening degree of an exhaust throttle valve disposed in the exhaust passage in order to control a temperature of the exhaust purification device in an internal combustion engine including an exhaust purification device disposed in the exhaust passage. About.

In an internal combustion engine including a gasoline engine and a diesel engine, a catalyst device such as an oxidation catalyst device or a NOx catalyst device is used as an exhaust gas purification device for purifying exhaust gas, and a filter device for collecting exhaust particulates is used in a diesel engine. . In these exhaust purification apparatuses, in order to maintain and improve the exhaust purification performance, in the catalyst apparatus, so as to quickly reach the activation temperature at which the catalyst becomes active and maintain a high purification rate, SOx ( In the NOx catalyst device that reduces the purification performance due to the adhesion of sulfur oxides) and the filter device that deteriorates the purification performance due to the adhesion of exhaust particulates, it is possible to reduce the attached SOx and burn the exhaust particulates to restore the purification performance It is necessary to raise the temperature to a suitable regeneration temperature.
Therefore, an exhaust throttle valve that is disposed downstream of the catalyst device that is disposed in the exhaust passage of the internal combustion engine and controls the flow rate of the exhaust gas, and a temperature detection means that detects the temperature of the catalyst device, the exhaust throttle valve is provided. By utilizing the fact that the temperature of the exhaust gas rises by increasing the exhaust pressure by closing, the catalyst device is controlled by controlling the opening of the exhaust throttle valve based on the temperature detected by the temperature detecting means There is known an exhaust control device that can reach the activation temperature early (see, for example, Patent Document 1).
Further, in an internal combustion engine including a catalyst device disposed in an exhaust passage, in order to increase the accuracy of temperature detection of the catalyst device by the temperature sensor, the catalyst is based on the flow rate of exhaust gas flowing through the exhaust passage and the output of the temperature sensor. It is known to estimate the temperature of the apparatus (for example, see Patent Document 2).
Japanese Patent No. 2817852 JP 2007-16653 A

When the temperature of the catalyst device is controlled by controlling the opening of the exhaust throttle valve according to the temperature of the catalyst device, the exhaust throttle valve is closed until the temperature of the catalyst device reaches a target temperature (for example, the activation temperature). When the target temperature is reached, the exhaust throttle valve is opened and changed to an intermediate opening, and when the temperature of the catalytic device reaches a temperature that accelerates catalyst deterioration, When the exhaust throttle valve opening is controlled in stages, such as when the exhaust throttle valve is fully opened, the temperature of the catalyst device is controlled to increase, the overshooting when the temperature rises above the target temperature, This causes an overshoot in which the temperature falls below the target temperature.
If overshoot occurs in this way, the purification rate falls outside the high temperature range, leading to a reduction in purification performance, or excessive increase in temperature or frequency thereof tends to cause deterioration of the catalyst device. Thus, the durability of the catalyst device may be reduced. Further, even in an exhaust purification device that requires a regeneration process for recovering the purification performance, the efficiency of the regeneration process may be reduced, or the durability of the exhaust purification device may be reduced due to an excessive temperature rise.
Even if the exhaust throttle valve opening is the same, if the exhaust gas flow rate is different, the exhaust gas temperature rise rate, and therefore the exhaust gas purification device temperature rise rate and fall rate, will also differ, so overshoot will occur. It becomes easier to generate.

  The present invention has been made in view of such circumstances, and the invention according to claims 1 to 5 is directed to an exhaust gas in a temperature control device that controls the temperature of an exhaust purification device through opening control of an exhaust throttle valve. It is an object to achieve stable maintenance of the target temperature by suppressing overshoot with respect to the target temperature while allowing the exhaust purification device to reach the target temperature early by considering the flow rate of the exhaust gas.

According to the first aspect of the present invention, the flow rate of the exhaust gas that is disposed upstream or downstream of the exhaust purification device (9) disposed in the exhaust passage (7) of the internal combustion engine (E) and flows through the exhaust passage (7). An exhaust throttle valve (10) for controlling the temperature, a temperature detection means (23) for detecting the temperature of the exhaust purification device (9), and an opening degree control means (30 for controlling the opening degree of the exhaust throttle valve (10)) And an exhaust flow rate detecting means (24) for detecting the flow rate of the exhaust gas in a temperature control device that controls the temperature of the exhaust purification device (9) by controlling the opening of the exhaust throttle valve (10). The opening degree control means (30) includes a target temperature (To) that is a temperature when the exhaust purification device (9) is in an active state or a temperature when it is in a regenerative state, and the temperature detection means. The temperature which is the absolute value of the difference from the actual temperature (T) detected by (23) A required opening (β) of the exhaust throttle valve (10) is calculated based on the degree difference (ΔT) and the exhaust flow rate (Qe) detected by the exhaust flow rate detecting means (24), and the exhaust throttle valve (10) is a temperature control device that controls the required opening degree (β).
According to a second aspect of the present invention, in the temperature control device according to the first aspect, the opening degree control means (30) is configured to change a temperature change amount (Tc) based on the temperature difference (ΔT) and the exhaust flow rate (Qe). ) For calculating the required opening degree (β) based on the temperature change amount (Tc) and an opening degree calculating means (32) for calculating the required opening degree (β).
According to a third aspect of the present invention, in the temperature control device according to the second aspect, when the actual temperature (T) is equal to or lower than the target temperature (To), the temperature change amount calculating means (31) When ΔT) is equal to or higher than a predetermined value (ΔT _L ) on the low temperature side, the temperature increase amount (Tu) that is the temperature change amount (Tc) is set to the maximum value (Tum), and the temperature difference (ΔT) is the predetermined value. When the temperature difference (ΔT) is less than (ΔT _L ), the temperature increase amount (Tu) is set to a value that continuously decreases in accordance with a decrease in the temperature difference (ΔT), and the opening degree calculation means (32) The required opening (β) is continuously increased in accordance with the decrease in (Tu).
According to a fourth aspect of the present invention, in the temperature control device according to the second or third aspect, when the actual temperature (T) exceeds the target temperature (To), the temperature change amount calculating means (31) When the difference (ΔT) is equal to or greater than a predetermined value (ΔT _H ) on the high temperature side, the temperature decrease amount (Td) that is the temperature change amount (Tc) is set to the maximum value (Tdm), and the temperature difference (ΔT) is When the temperature difference (ΔT) is less than a predetermined value (ΔT _H ) on the high temperature side, the temperature decrease amount (Td) is continuously decreased in accordance with the decrease in the temperature difference (ΔT), and the opening degree calculation means (32) The required opening degree (β) is continuously decreased in accordance with the decrease in the temperature decrease amount (Td).
According to a fifth aspect of the present invention, in the temperature control device according to the third or fourth aspect, the predetermined values (ΔT _L , ΔT _H ) increase as the exhaust flow rate (Qe) increases.

According to the first aspect of the present invention, in addition to the temperature difference between the target temperature and the actual temperature detected by the temperature detection means, the opening of the exhaust throttle valve for controlling the temperature of the exhaust purification device is not limited to the exhaust flow rate. Since the control is also based on the exhaust flow rate detected by the detection means, the temperature of the exhaust purification device can quickly reach the target temperature, and the temperature of the exhaust purification device can overshoot the target temperature. It is suppressed and the target temperature can be stably maintained. As a result, it is possible to improve the purification performance and the efficiency of the regeneration process for recovering the purification performance, and further it is possible to prevent an excessive temperature rise and improve the durability of the exhaust purification device. .
According to the second aspect of the present invention, even when the opening degree of the exhaust throttle valve is controlled based on the temperature difference between the target temperature and the actual temperature and the exhaust flow rate, the temperature change amount calculation means calculates the temperature difference. Since the temperature change amount corrected by the exhaust flow rate is set, the available opening degree calculation means can be used as it is for the temperature change amount calculation means set based only on the temperature difference.
According to the third aspect of the present invention, when the temperature of the exhaust gas purification device is raised to the target temperature, the temperature continuously decreases when the temperature difference between the target temperature and the actual temperature becomes smaller than a predetermined value and becomes smaller. Since the required opening of the exhaust throttle valve continuously increases with the amount of increase, it is possible to effectively suppress overshoot with respect to the target temperature when the temperature of the exhaust purification device rises.
According to the fourth aspect of the present invention, when the temperature of the exhaust purification device is lowered to the target temperature, the temperature continuously decreases when the temperature difference between the target temperature and the actual temperature becomes smaller than a predetermined value and becomes smaller. Since the required opening of the exhaust throttle valve decreases continuously with the amount of lowering, the overshoot with respect to the target temperature when the temperature drops when the required opening of the exhaust throttle valve increases and the target when the temperature rises when the required opening becomes smaller The overshoot with respect to temperature can be effectively suppressed.
According to the fifth aspect of the present invention, when the exhaust gas flow rate increases, the amount of temperature change starts to decrease from a time when the temperature difference is relatively large, so that overshoot with respect to the target temperature can be further suppressed.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
Referring to FIG. 1, a temperature control device to which the present invention is applied is provided in an internal combustion engine E that is a diesel engine mounted on a vehicle.
The internal combustion engine E includes an engine body 1 provided with a combustion chamber and a piston that is driven by the pressure of the combustion gas in the combustion chamber to rotationally drive a crankshaft, an air cleaner 3, and intake air that guides intake air to the combustion chamber. An intake device 2 that forms a passage 4, a fuel injection valve 5 that forms fuel-air mixture by injecting fuel into the intake air in the combustion chamber, and exhausts combustion gas generated by combustion of the fuel-air mixture in the combustion chamber And an exhaust device 6 that forms an exhaust passage 7 that leads to the outside of the internal combustion engine E as gas.

The intake device 2 includes an intake throttle valve 8 that is disposed in the intake passage 4 and controls the flow rate of intake air that is sucked into the combustion chamber.
The exhaust device 6 includes a lean NOx catalyst device 9 that is a catalyst device that is disposed in the exhaust passage 7 and purifies exhaust gas, and an exhaust throttle valve 10 that controls the flow rate of exhaust gas flowing through the exhaust passage 7. Is provided.
An exhaust throttle valve 10 composed of a butterfly valve is disposed downstream of the catalyst device 9 in the exhaust passage 7.
The catalyst device 9 is, for example, a catalyst device in which platinum or the like is supported on a carrier, or a selective reduction type catalyst device in which iridium and an alkaline earth metal are supported on a carrier made of metal carbide or metal nitride.

The internal combustion engine E is further an operation control device 11 that controls the operation state of the internal combustion engine E, an actuator 12 that is a drive unit that drives the intake throttle valve 8 to open and close, and a drive unit that drives the exhaust throttle valve 10 to open and close. And an actuator 13.
Referring also to FIG. 2, the operation control device 11 includes an engine state detection unit 20 that detects the state of the internal combustion engine E, such as an operation state of the internal combustion engine E, and an engine state detected by the engine state detection unit 20. An electronic control unit (hereinafter referred to as “ECU”) 15 for controlling the operation of the fuel injection valve 5 and the actuators 12 and 13 is provided. The operations of the fuel injection valve 5 and the actuators 12 and 13 are controlled by a drive signal output from the ECU 15.
The ECU 15 includes fuel injection control means 16 and opening degree control means 17 and 30 for controlling the fuel injection valve 5 and the exhaust throttle valve 10 according to the engine state detected by the engine state detection means 20, respectively.
The ECU 15 is composed of a computer including an input / output interface, a central processing unit, a ROM storing various control programs and various maps, and a storage device having a RAM temporarily storing various data. . Then, the map, the map _{M L,} M H to be described later, it includes Mv (see FIG. 6).

The engine state detection means 20 includes a rotation speed detection means 21 for detecting the engine rotation speed Ne of the internal combustion engine E based on the rotation position of the crankshaft, an accelerator operation amount detection means 22 for detecting the accelerator operation amount A, and a catalyst device. The temperature detection means 23 for detecting the actual temperature T, which is the temperature 9, the exhaust flow rate detection means 24 for detecting the exhaust flow rate Qe, which is the flow rate of the exhaust gas flowing through the exhaust passage 7, and the intake throttle valve 8 in the intake passage 4 And an air flow meter 25 that is disposed upstream to detect the intake air amount Qa and a fuel amount detection means 26 that detects the fuel amount Qf injected from the fuel injection valve 5.
The temperature of the catalyst device 9 includes the temperature of the catalyst itself in the catalyst device 9, the temperature of the carrier supporting the catalyst, or the temperature of the exhaust gas having a temperature that is an index of the temperature of the catalyst or the carrier.
The exhaust flow rate detection means 24 calculates the exhaust flow rate Qe based on the intake air amount Qa detected by the air flow meter 25 and the fuel amount Qf detected by the fuel amount detection means 26.
Here, a part or all of the detection means of the rotational speed detection means 21, the air flow meter 25, the fuel amount detection means 26, and the exhaust flow rate detection means 24, and the control means are respectively functions of the ECU 15 as functions of the ECU 15. Prepared for.

The fuel injection control means 16 includes a fuel quantity Qf injected from the fuel injection valve 5 in accordance with the engine rotational speed Ne detected by the rotational speed detection means 21 and the accelerator operation quantity A detected by the accelerator operation quantity detection means 22. Control injection timing.
The intake opening control means 17 outputs a drive signal to the actuator 12 based on the accelerator operation amount A to control the opening of the intake throttle valve 8.

  The exhaust opening control means 30 is a temperature difference ΔT (see FIG. 6) which is an absolute value of a difference between the target temperature To (see FIG. 7) which is a temperature when the catalyst device 9 is in an active state and the actual temperature T. And the required opening degree β of the exhaust throttle valve 10 is calculated based on the exhaust flow rate Qe, and the opening degree of the exhaust throttle valve 10 is controlled so as to be the required opening degree β.

The target temperature To is a temperature that is higher than the activation temperature Ta (see FIG. 7) of the catalyst device 9 by a predetermined temperature. Here, the activation temperature Ta is the lowest temperature when the catalyst device 9 is in the activated state. Therefore, the activation temperature Ta and the target temperature To are both temperatures when the catalyst device 9 is in the active state.
The predetermined temperature is set to a temperature at which the purification rate is highest or a temperature in the vicinity thereof from the viewpoint of maintaining good purification performance without the temperature of the catalyst device 9 becoming less than the activation temperature Ta due to temperature fluctuations of the exhaust gas. The

  The opening degree control means 30 includes a temperature change amount calculation means 31 for calculating a temperature change amount Tc based on the temperature difference ΔT and the exhaust flow rate Qe, and an opening ratio α of the exhaust throttle valve 10 based on the temperature change amount Tc (FIG. 5). The aperture ratio calculating means 33 for calculating the aperture ratio α, and the conversion means 34 for converting the aperture ratio α into the required opening degree β. Here, the opening ratio calculating means 33 and the converting means 34 constitute an opening degree calculating means 32 for calculating the required opening degree β of the exhaust throttle valve 10 based on the temperature change amount Tc. Further, as shown in FIG. 5, the temperature change amount Tc includes a temperature increase amount Tu that increases the temperature of the catalyst device 9 and a temperature decrease amount Td that decreases the temperature of the catalyst device 9.

2 to 4, the temperature change amount calculation means 31 calculates a temperature difference ΔT that is an absolute value of a difference between the target temperature To and the actual temperature T, and further changes the temperature difference ΔT and the exhaust flow rate Qe as variables. The temperature change amount Tc based on the temperature difference ΔT and the exhaust gas flow rate Qe is calculated by searching the maps M _L and M _H (see FIG. 6) which are three-dimensional maps.
Specifically, as shown in FIG. 3, the temperature increase map M _L the actual temperature T is searched when: the target temperature To (see Fig. 7), the temperature rise amount Tu is the temperature change amount Tc a continuous temperature rise Tu in response to the decrease of the temperature difference [Delta] T when the maximum value Tum, and the temperature difference [Delta] T is less than a predetermined value [Delta] T _L when the temperature difference [Delta] T is equal to or higher than a predetermined value [Delta] T _L of the low-temperature side It is set so as to become a decreasing value.
Further, as shown in FIG. 4, in the temperature decrease amount map _MH searched when the actual temperature T exceeds the target temperature To, the temperature decrease amount Td, which is the temperature change amount Tc, is such that the temperature difference ΔT is higher. maximum value Tdm next when a predetermined value or more [Delta] T _H of, as the temperature difference [Delta] T becomes a value temperature lowering amount Td decreases continuously in accordance with a decrease of the temperature difference [Delta] T when it is less than the predetermined value [Delta] T _H Is set to
Each predetermined value [Delta] T _L, [Delta] T _H from the viewpoint of suppressing overshoot during overshoot and temperature fall when the temperature is raised to the target temperature To, is set appropriately through experiments or the like.

When the flow rate of the exhaust gas is large, the amount of heat transferred per unit time between the exhaust gas and the catalyst device 9 (see FIG. 1) becomes large. as illustrated by the Q _{e1, Q e2,} flow the predetermined value [Delta] T _L in accordance with the increase of the exhaust gas, so that [Delta] T _H increases, the predetermined value [Delta] T _L, [Delta] T _H is in accordance with the exhaust flow Qe Be changed. Here, the exhaust flow rate Q _e2 is larger than the exhaust flow rate Q _e1 .
Incidentally, FIG. 3, 4, characteristics shown by solid line shows the exhaust flow rate Q _e1, Q low exhaust flow rate than _e2 Q temperature difference ΔT at _e and temperature increase Tu, the relationship between the temperature lowering amount Td ing.

  Further, when the temperature change amount calculating means 31 calculates the temperature change amount Tc, the accuracy of the opening control of the exhaust throttle valve 10 is improved by adding correction based on the temperature of the exhaust gas detected by the temperature detecting means 23. As a result, the accuracy of temperature control of the catalyst device 9 can be improved.

Referring to FIGS. 2 and 5, the opening degree calculation means 32 searches the opening ratio map Mv which is a two-dimensional map with the temperature change amount Tc calculated by the temperature change amount calculation means 31 as a variable. An opening ratio α corresponding to the temperature change amount Tc is calculated, and a necessary opening degree β of the exhaust throttle valve 10 (see FIG. 1) corresponding to the opening ratio α is calculated. In the map Mv, the aperture ratio α is set to continuously increase (or decrease) in accordance with a decrease (or increase) in the temperature increase amount Tu and an increase (or decrease) in the temperature decrease amount Td.
Here, the opening ratio α is the ratio of the opening area of the opening other than when the exhaust throttle valve 10 is fully opened to the opening area when the exhaust throttle valve 10 is fully opened, and has a continuous value between the minimum opening and the fully opened. The minimum opening is an opening for allowing the exhaust gas to be discharged to allow the internal combustion engine E to operate.
The conversion means 34 outputs a drive signal for setting the opening of the exhaust throttle valve 10 to the required opening β to the actuator 13.

When the opening degree of the exhaust throttle valve 10 is a predetermined opening ratio αc (or the opening degree of the exhaust throttle valve 10 is a predetermined opening degree), the temperature of the catalyst device 9 (see FIG. 1) is set to the target temperature To (FIG. 7). Reference) is maintained. For this reason, the exhaust throttle valve 10 moves to the closing side at the predetermined opening ratio αc and the opening ratio α decreases, whereby the pressure of the exhaust gas upstream of the exhaust throttle valve 10 in the exhaust passage 7 increases. As the exhaust gas temperature also rises, the temperature of the catalyst device 9 rises. On the other hand, when the exhaust throttle valve 10 moves to the opening side at the predetermined opening ratio αc and the opening ratio α increases, the pressure of the exhaust gas upstream of the exhaust throttle valve 10 in the exhaust passage 7 decreases. As the temperature of the exhaust gas also decreases, the temperature of the catalyst device 9 decreases.
Therefore, the exhaust throttle valve 10, the temperature detection means 23, the exhaust flow rate detection means 24, and the opening degree control means 30 are temperature control devices that control the temperature of the catalyst device 9 by controlling the opening degree of the exhaust throttle valve 10. Constitute.

With reference mainly to FIG. 6 with reference to FIG. 2, the temperature control procedure of the catalyst device 9 executed every predetermined time (for example, 10 ms) by the temperature control device and the function of the temperature control device will be described. .
After the operation of the internal combustion engine E is started, in step S1, the actual temperature T of the catalyst device 9 (see FIG. 1) detected by the temperature detection means 23 and the exhaust flow rate Qe detected by the exhaust flow rate detection means 24 are read. Next, in step S2, the target temperature To of the catalyst device 9 is compared with the actual temperature T. When the determination in step S2 is affirmative and the actual temperature T is equal to or lower than the target temperature To, the process proceeds to step S3. A temperature difference ΔT that is an absolute value of a difference between the target temperature To and the actual temperature T is calculated.
Thereafter, in step S4, it is retrieved map M _L based on the temperature difference ΔT and the exhaust gas flow rate Qe, the temperature rise amount Tu corresponding to the temperature difference ΔT and the exhaust gas flow rate Qe is calculated.

Next, the process proceeds to step S5, where the opening ratio α of the exhaust throttle valve 10 for realizing the temperature increase amount Tu that is the temperature change amount Tc (see FIG. 5) obtained in step S4 is searched by searching the map Mv. Calculated. Then, the opening ratio α is converted into the required opening β, and the required opening β of the exhaust throttle valve 10 is calculated.
Thereafter, in step S6, a drive signal for obtaining the required opening degree β is output to the actuator 13, and the exhaust throttle valve 10 is driven so as to have the required opening degree β.
The function of the ECU 15 in steps S5 and S6 constitutes the opening degree calculation means 32.
When the actual temperature T is equal to or lower than the target temperature To, the control constituted by the steps S1 to S6 is repeatedly executed every predetermined time, and the arrival of the catalyst device 9 to the activation temperature Ta is accelerated, thereby purifying. Performance is improved and overshoot is suppressed.

On the other hand, when the determination in step S2 is negative and the actual temperature T exceeds the target temperature To, the process proceeds to step S7, where a temperature difference ΔT that is an absolute value of the difference between the target temperature To and the actual temperature T is calculated. Thereafter, in step S8, the map _MH is searched based on the temperature difference ΔT and the exhaust flow rate Qe, and the temperature decrease amount Td corresponding to the temperature difference ΔT and the exhaust flow rate Qe is calculated.
Therefore, the function of the ECU 15 in steps S3, S4, S7, and S8 constitutes the temperature change amount calculation means 31.
Next, proceeding to step S5, the opening ratio α of the exhaust throttle valve 10 for realizing the temperature decrease amount Td obtained at step S7 is calculated by searching the map Mv. Then, the required opening degree β is calculated based on the opening ratio α, and in step S6, a drive signal is output to the actuators 12 and 13, and the exhaust throttle valve 10 is driven so as to have the required opening degree β.
By controlling the temperature of the catalyst device 9 by this temperature control device, as shown in FIG. 7, in the temperature rising process of the catalyst device 9 where the actual temperature T is equal to or lower than the target temperature To, the exhaust gas is exhausted when the temperature difference ΔT is large. The required opening β of the throttle valve 10 is maintained at the minimum opening (see also FIG. 5), the temperature of the catalyst device 9 rises quickly, and the early arrival at the activation temperature Ta is realized, and the temperature difference ΔT The required opening degree β of the opening degree of the exhaust throttle valve 10 is continuously increased according to the decrease, and the overshoot after reaching the target temperature To is suppressed. Further, in the target temperature maintaining process after the temperature of the catalyst device 9 has reached the target temperature To, overshoot at the time of temperature decrease and temperature increase with respect to the target temperature To is suppressed.

  When the actual temperature T exceeds the target temperature To, the control configured by steps S7, S8, S5, and S6 is repeatedly performed at the predetermined time, and the temperature of the catalyst device 9 is set to the target temperature To. Overshoot is suppressed and the temperature is stably maintained at the target temperature To.

Next, operations and effects of the embodiment configured as described above will be described.
Exhaust flow rate at which the temperature control device that controls the temperature of the catalyst device 9 by controlling the opening degree of the exhaust throttle valve 10 by the opening degree control means 30 that controls the opening degree of the exhaust throttle valve 10 detects the flow rate of the exhaust gas. A detection means 24 is provided, and the opening degree control means 30 is a temperature that is an absolute value of a difference between a target temperature To that is a temperature when the catalyst device 9 is in an active state and an actual temperature T that is detected by the temperature detection means 23. Based on the difference ΔT and the exhaust flow rate Qe detected by the exhaust flow rate detection means 24, the required opening β of the exhaust throttle valve 10 is calculated, and the exhaust throttle valve 10 is controlled to the required opening β, whereby the catalyst device The opening of the exhaust throttle valve 10 for controlling the temperature 9 is detected by the exhaust flow rate detection means 24 in addition to the temperature difference ΔT between the target temperature To and the actual temperature T detected by the temperature detection means 23. Since it is also controlled based on the exhaust flow rate Qe, Degrees can quickly be to reach the target temperature To, yet is suppressed that the temperature of the catalyst device 9 is overshooting the target temperature To, can maintain a target temperature To stably. As a result, the purification performance can be improved, and an excessive temperature rise can be prevented, and the durability of the catalyst device 9 can be improved.

  The opening degree control means 30 includes a temperature change amount calculation means 31 that calculates the temperature change amount Tc based on the temperature difference ΔT and the exhaust flow rate Qe, and an opening degree calculation means that calculates the required opening degree β based on the temperature change amount Tc. 32, even when the opening degree of the exhaust throttle valve 10 is controlled based on the temperature difference ΔT between the target temperature To and the actual temperature T and the exhaust flow rate Qe, the temperature change amount calculation means 31 Thus, the temperature change amount Tc in which the temperature difference ΔT is corrected by the exhaust flow rate Qe is set, so that the opening degree calculation means 32 that can be used for the temperature change amount calculation means 31 set based only on the temperature difference ΔT. Can be used as is.

When the actual temperature T is below the target temperature To, the temperature change amount calculating means 31, a temperature rise amount Tu is the temperature change amount Tc and the maximum value Tum when the temperature difference [Delta] T is a predetermined value [Delta] T _L or more low-temperature side , a value that continuously decreases the temperature rise Tu according to the decrease of the temperature difference [Delta] T when the temperature difference [Delta] T is less than a predetermined value [Delta] T _L, the opening degree calculating means 32, according to the decrease of the temperature rise amount Tu by increasing continuously required opening β Te, when raising the temperature of the catalytic converter 9 up to the target temperature to, when the temperature difference [Delta] T is reduced becomes less than the predetermined value [Delta] T _L, continuously decreases Since the required opening degree β of the exhaust throttle valve 10 continuously increases with the temperature rise amount Tu, overshooting with respect to the target temperature To when the temperature of the catalyst device 9 rises can be effectively suppressed.

When the actual temperature T exceeds the target temperature To, the temperature change amount calculating means 31, the temperature lowering amount Td is a temperature change amount Tc and the maximum value Tdm when the temperature difference [Delta] T is equal to or higher than a predetermined value [Delta] T _H of the high-temperature side , a value that continuously decreases the temperature lowering amount Td according to the decrease of the temperature difference [Delta] T when the temperature difference [Delta] T is less than a predetermined value [Delta] T _H, opening calculation means 32, according to the decrease of the temperature lowering amount Td by reducing continuously the required opening β Te, when lowering the temperature of the catalytic converter 9 up to the target temperature to, is the temperature difference [Delta] T between the target temperature to and the actual temperature T is less than the predetermined value [Delta] T _H Since the required opening degree β of the exhaust throttle valve 10 continuously decreases together with the temperature decrease amount Td that continuously decreases, the target temperature at the time of temperature decrease when the required opening degree β of the exhaust throttle valve 10 increases. Overshoot against To and the necessary opening The overshoot with respect to the target temperature To at the time of temperature rise when the degree β becomes small can be effectively suppressed.

Predetermined value [Delta] T _L, [Delta] T _H, by the exhaust gas flow rate Qe is increased in response to increases, exhaust gas when the flow rate Qe is increased, the temperature change amount Tc from time temperature difference [Delta] T is relatively large starts to decrease Further, the overshoot with respect to the target temperature To can be further suppressed.

Hereinafter, a mode in which a part of the above-described embodiment is changed will be described focusing on the changed portion.
The exhaust throttle valve 10 is disposed downstream of the catalyst device 9 (that is, the exhaust gas purification device) in the above-described embodiment, but may be disposed upstream of the catalyst device 9 in the exhaust passage 7. That is, when the exhaust throttle valve 10 is arranged upstream of the catalyst device 9, the speed is increased by passing through the gap between the exhaust passage 7 and the exhaust throttle valve 10 when the opening degree of the exhaust throttle valve 10 is small. By disposing the catalyst device 9 at a position where the exhaust gas flows through the catalyst device 9, the amount of heat transferred from the exhaust gas to the catalyst device 9 per unit time is increased, and the temperature increase of the catalyst device 9 is promoted. be able to.
The temperature change amount calculation means 31 uses a plurality of exhaust flow rates Qe as parameters, and a temperature change amount corresponding to the exhaust flow rate Qe with respect to the temperature difference ΔT based on a two-dimensional map in which the temperature change amount Tc with respect to the temperature difference ΔT is set. The temperature change amount Tc may be calculated by interpolation with respect to the temperature difference ΔT and the temperature change amount Tc having discrete values.
The exhaust purification device may be a NOx catalyst device in which the purification performance decreases due to adhesion of SOx (sulfur oxide), or a filter device in which the purification performance decreases due to adhesion of exhaust particulates. In these cases, The target temperature is a regeneration temperature at which the attached SOx can be reduced and exhaust particulates can be combusted to recover the purification performance. The temperature control device at this time makes it possible to improve the efficiency of the regeneration process for recovering the purification performance, and further, the excessive temperature rise can be prevented to improve the durability of the exhaust purification device. it can.
The exhaust purification device may be an oxidation catalyst as a catalyst device.
The internal combustion engine may be a spark ignition type internal combustion engine, and the exhaust purification device may be a three-way catalyst device as a catalyst device.
The target temperature may be an activation temperature.

It is a mimetic diagram of an internal-combustion engine provided with a temperature control device to which the present invention was applied. It is a block diagram of the operation control apparatus of the internal combustion engine of FIG. It is a figure explaining the map used for calculation of the temperature rise amount in a temperature control apparatus. It is a figure explaining the map used for calculation of the amount of temperature fall in a temperature control device. It is a figure explaining the map used for calculation of the aperture ratio of an exhaust throttle valve in a temperature control apparatus. It is a flowchart explaining the control procedure and function of a temperature control apparatus. It is a figure explaining the change of the opening degree of the exhaust throttle valve by the temperature control apparatus, and the temperature of a catalyst apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 7 ... Exhaust passage, 9 ... Catalytic device, 10 ... Exhaust throttle valve, 11 ... Operation control device, 15 ... ECU, 23 ... Temperature detection means, 24 ... Exhaust flow rate detection means, 30 ... Opening control means, 31 ... Temperature change Amount calculation means, 32... Opening calculation means,
E ... internal combustion engine, T ... actual temperature, the To ... target temperature, Ta ... activation temperature, [Delta] T ... temperature difference, Tu ... temperature increase, Td ... temperature drop amount, ΔT _L, ΔT H _... predetermined value.

Claims (5)

An exhaust throttle valve that controls the flow rate of exhaust gas that is arranged upstream or downstream of the exhaust purification device that is arranged in the exhaust passage of the internal combustion engine and flows through the exhaust passage, and a temperature detection means that detects the temperature of the exhaust purification device And an opening control means for controlling the opening of the exhaust throttle valve, and a temperature control device for controlling the temperature of the exhaust purification device by controlling the opening of the exhaust throttle valve,
An exhaust flow rate detecting means for detecting the exhaust gas flow rate is provided,
The opening degree control means is an absolute value of a difference between a target temperature which is a temperature when the exhaust purification device is in an active state or a temperature when the exhaust purification device is in a reproducible state and an actual temperature detected by the temperature detection means. A temperature that calculates a required opening of the exhaust throttle valve based on a certain temperature difference and an exhaust flow rate detected by the exhaust flow rate detecting means, and controls the exhaust throttle valve to the required opening degree. Control device.   The opening degree control means includes a temperature change amount calculating means for calculating a temperature change amount based on the temperature difference and the exhaust flow rate, and an opening degree calculating means for calculating the required opening degree based on the temperature change amount. The temperature control device according to claim 1, comprising: When the actual temperature is less than or equal to the target temperature, the temperature change amount calculation means sets the temperature increase amount that is the temperature change amount as a maximum value when the temperature difference is equal to or greater than a predetermined value on the low temperature side, and the temperature difference When the temperature difference is less than the predetermined value, the temperature increase amount is continuously reduced according to the decrease in the temperature difference,
The temperature control apparatus according to claim 2, wherein the opening degree calculation means continuously increases the required opening degree according to a decrease in the temperature increase amount. When the actual temperature exceeds the target temperature, the temperature change amount calculation means sets the temperature decrease amount that is the temperature change amount as a maximum value when the temperature difference is greater than or equal to a predetermined value on the high temperature side, and the temperature difference When the temperature is less than a predetermined value on the high temperature side, the temperature decrease amount is a value that continuously decreases in accordance with the decrease in the temperature difference,
4. The temperature control apparatus according to claim 2, wherein the opening degree calculation means continuously reduces the required opening degree according to a decrease in the temperature decrease amount.   The temperature control apparatus according to claim 3 or 4, wherein the predetermined value increases as the exhaust flow rate increases.

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