JP2010065631A - Catalyst poisoning detoxification control device for vehicle internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately grasp the poisoning amount of a bypass catalytic converter 8 and to prevent the poisoning release control from being performed more than necessary, and to prevent thermal deterioration of the bypass catalytic converter 8 and deterioration of operation performance due to this. .
SOLUTION: By closing an upstream side of a main passage 3 in which a main catalytic converter 4 is interposed by a bypass valve 5, exhaust gas flows into a bypass passage 7 in which a bypass catalytic converter 8 is interposed. When the main passage 3 is closed by the bypass valve 5, the poisoning amount of the bypass catalytic converter 8 is added or subtracted based on the catalyst temperature, the poisoning amount reaches a predetermined poisoning release determination amount, and When predetermined operating conditions are satisfied, poisoning release control is performed.
[Selection] Figure 1

Description

  The present invention relates to an internal combustion engine for a vehicle, and more particularly to poisoning release control of a bypass catalytic converter provided in a bypass passage.

  As conventionally known, in a configuration in which the main catalytic converter is disposed relatively downstream of the exhaust system such as under the floor of a vehicle, the temperature of the catalytic converter rises and is activated after a cold start of the internal combustion engine. In the meantime, a sufficient exhaust purification action cannot be expected. On the other hand, the closer the catalytic converter is to the upstream side of the exhaust system, that is, the internal combustion engine side, the lower the durability due to thermal degradation of the catalyst.

  Therefore, as described in Patent Document 1, a bypass channel is provided in parallel with the upstream portion of the main channel including the main catalytic converter, and another bypass catalytic converter is interposed in the bypass channel. An exhaust device has been conventionally proposed in which exhaust gas is guided to the bypass flow path side immediately after cold start by a bypass valve that is a switching valve for switching between the two. In this configuration, the bypass catalytic converter is positioned relatively upstream of the main catalytic converter in the exhaust system and is activated relatively early, so that exhaust purification can be started from an earlier stage. it can.

On the other hand, the catalytic converter may be poisoned during its use, and it is necessary to maintain the original catalytic reaction by appropriately regenerating it. In the above-mentioned Patent Document 1, the catalyst poisoning of the bypass catalytic converter due to a small amount of exhaust gas flowing to the bypass catalytic converter side when the bypass valve is opened is determined based on the engine operating conditions, the intake air amount, the operating time when the bypass valve is open, and the like. When the determination is made based on this and it is determined that the bypass catalytic converter is poisoned, the bypass valve is closed, exhaust gas is flowed to the bypass catalytic converter side, poisoning control is performed, and the catalyst is regenerated.
JP 2008-038788 A

  In the above Patent Document 1, the poisoning of the bypass catalytic converter when the bypass valve is opened is integrated and determined. If there is no leakage of the bypass valve due to the structure of the exhaust system flow path, the bypass valve is opened when the bypass valve is opened. Since the exhaust gas hardly flows to the passage side, the influence of poisoning of the bypass catalytic converter is small, and actually, the influence of poisoning when the bypass valve is closed is much larger. Further, in the above-mentioned Patent Document 1, it is assumed that the poisoning is not performed when the bypass valve is closed. However, in many cases, the bypass catalytic converter is actually operated at a temperature lower than the temperature at which the poisoning can be released. It is not considered that the temperature decreases when the bypass catalytic converter is reached due to the increase in the heat mass of the exhaust system on the side, and the catalyst poisoning amount is not considered. In the above-mentioned Patent Document 1, addition / subtraction of the catalyst poisoning amount of the bypass catalytic converter during the poisoning release control is not performed. Therefore, the poisoning release control is performed more than necessary, which may cause thermal deterioration of the bypass catalytic converter. There is. In addition, closing the bypass valve to eliminate poisoning may cause excessive temperature rise on the bypass catalytic converter side, and adversely affect engine operating performance and fuel consumption performance due to exhaust flow restriction and increased ventilation resistance. Therefore, the poisoning release control must be kept to a minimum.

  The present invention has been made in view of such a problem, and while performing the poisoning release control of the bypass catalytic converter satisfactorily, excessive temperature rise and engine operability of the bypass catalytic converter accompanying the poisoning release control are achieved. The present invention provides a novel catalyst poisoning release control device for an internal combustion engine for a vehicle that can eliminate the above-described decrease.

  A main passage through which exhaust exhausted from the cylinder flows, a main catalytic converter interposed in the main passage, a branch from the main passage on the upstream side of the main catalytic converter, and a passage cross-sectional area larger than the main passage A vehicle internal combustion engine comprising: a small bypass passage; a bypass catalytic converter provided in the bypass passage; and a main passage closing means for closing the main passage so that exhaust discharged from the cylinder flows to the bypass passage. In the catalyst poisoning release control device, when it is determined that the main passage is closed by the main passage closing means, and when the main passage is determined to be closed by the opening / closing determination means, Poisoning amount addition / subtraction means for adding / subtracting the poisoning amount of the bypass catalytic converter, and the poisoning amount is a predetermined poisoning Reaching removal determination amount, and, if it meets the predetermined operating condition is characterized by having a poisoning removal control means for poisoning removal control.

  The determination of the opening / closing of the main passage by the opening / closing determination means is performed based on the catalytic activation state of the main catalytic converter, etc. separately from the poisoning release control process, and generally the main catalytic converter is in an inactive state. And closed when the main catalytic converter is activated. That is, the main passage is not closed for poisoning release control. When the main passage is closed by the open / close determination means, the poisoning amount of the bypass catalytic converter is added or subtracted, and poisoning release control is performed based on the poisoning amount.

  According to the present invention, the poisoning amount of the bypass catalytic converter is added / subtracted when the main passage is closed, and the poisoning release control is performed based on the poisoning amount, thereby simplifying the control. The poisoning amount of the bypass catalytic converter can be accurately grasped, and the main passage is not closed for releasing the poisoning. Therefore, while performing the catalyst regeneration by the poisoning cancellation control well, it prevents the poisoning cancellation control from being performed more than necessary, and suppresses the adverse effects on the thermal degradation of the bypass catalytic converter and the engine operability caused by this. It can be avoided.

  Hereinafter, an embodiment in which the present invention is applied to an in-line four-cylinder internal combustion engine for a vehicle will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory view schematically showing the piping layout and control system of the exhaust device of the internal combustion engine. First, the configuration of the exhaust device will be described based on FIG.

  In the cylinder head 1a of the internal combustion engine 1, exhaust ports 2 of cylinders # 1 to # 4 arranged in series are formed so as to open toward the side surfaces, respectively. In addition, the main passage 3 is connected. The four main passages 3 of the # 1 cylinder to the # 4 cylinder merge into one flow path, and the main catalytic converter 4 is disposed on the downstream side thereof. The main catalytic converter 4 has a large capacity arranged under the floor of the vehicle, and includes, for example, a three-way catalyst and an HC trap catalyst as the catalyst. The main passage 3 and the main catalytic converter 4 constitute a main passage through which exhaust flows during normal operation. Further, a bypass valve 5 as a main passage closing means for opening and closing the main passages 3 at the same time is provided at the junction of the four main passages 3 from each cylinder. The bypass valve 5 is driven to open and close by an appropriate actuator 5a.

  On the other hand, bypass passages 7 each having a smaller passage sectional area than the main passage 3 are branched from the main passages 3 of the respective cylinders as bypass passages. The branch point 6 that is the upstream end of each bypass passage 7 is set to a position on the upstream side of the main passage 3 as much as possible. The four bypass passages 7 merge into one flow path on the downstream side, and a bypass catalytic converter 8 using a three-way catalyst is interposed immediately after the junction. The bypass catalytic converter 8 has a small capacity as compared with the main catalytic converter 4, and preferably uses a catalyst excellent in low-temperature activity. A downstream end of the bypass passage 7 extending from the outlet side of the bypass catalytic converter 8 is connected to the main passage 3 at a junction 12 upstream of the main catalytic converter 4 in the main passage 3 and downstream of the bypass valve 5. . Air-fuel ratio sensors 10, 11, and 13 are disposed at the inlet and outlet of the main catalytic converter 4 and the inlet of the bypass catalytic converter 8, respectively.

  The internal combustion engine 1 includes a spark plug 21, and a fuel injection valve 23 is disposed in the intake passage 22. Furthermore, a so-called electronically controlled throttle valve 24 that is opened and closed by an actuator such as a motor is disposed upstream of the intake passage 22, and an air flow meter 25 that detects the intake air amount is provided downstream of the air cleaner 26. Yes.

  Various control parameters of the internal combustion engine 1, for example, the fuel injection amount by the fuel injection valve 23, the ignition timing by the spark plug 21, the opening degree of the throttle valve 24, the open / close state of the bypass valve 5, etc. are controlled by the engine control unit 27. Is done. In addition to the sensors described above, the engine control unit 27 includes various sensors such as a coolant temperature sensor 28 and an accelerator opening sensor 29 that detects the opening (depression amount) of an accelerator pedal operated by a driver. Detection signal is input. Further, as a means for detecting the catalyst temperature of the bypass catalytic converter 8, before and after the bypass catalytic converter 8, a bypass catalyst inlet exhaust temperature sensor 30 for detecting the catalyst inlet gas temperature FGASTTEMP of the bypass catalytic converter 8, and the bypass catalytic converter 8 are provided. And a bypass catalyst outlet exhaust temperature sensor 31 for detecting the catalyst outlet gas temperature RGASTTEMP.

  In such a configuration, when the engine temperature or the exhaust temperature after the cold start is low, the bypass valve 5 is closed via the actuator 5a and the main passage 3 is shut off. Therefore, the entire amount of exhaust discharged from each cylinder flows from the branch point 6 to the bypass catalytic converter 8 through the bypass passage 7. The bypass catalytic converter 8 is located upstream of the exhaust system, that is, at a position close to the exhaust port 2 and is small in size, so that it is activated quickly and exhaust purification is started at an early stage.

  On the other hand, when the engine warm-up proceeds and the engine temperature or the exhaust temperature becomes sufficiently high, it is considered that the catalyst of the main catalytic converter 4 is activated as one of the trigger conditions, and the bypass valve 5 is opened. Thus, the exhaust discharged from each cylinder mainly passes through the main catalytic converter 4 from the main passage 3. At this time, the bypass passage 7 side is not particularly cut off, but the bypass passage 7 side has a smaller passage cross-sectional area than the main passage 3 side and the bypass catalytic converter 8 is interposed. Due to the difference, most of the exhaust flow passes through the main passage 3 side and hardly flows into the bypass passage 7 side.

  As a result, the main passage closing means for switching the flow of exhaust gas can be configured by the bypass valve 5 that only closes or opens the main passage 3 without requiring a complicated switching valve. Further, the thermal deterioration of the bypass catalytic converter 8 can be sufficiently suppressed.

  It should be noted that when the bypass valve 5 is closed and the exhaust flow flows through the bypass passage 7, the bypass valve 5 is controlled to be closed because it cannot cope with a high speed range or a high load range where the exhaust flow rate becomes large. Basically, the engine operating conditions (load and engine speed) are limited to a predetermined range on the low-speed and low-load side. In other regions, the main catalytic converter 4 is basically inactive. Even if it exists, the bypass valve 5 will be in an open state.

  When the bypass valve 5 is opened, almost no exhaust gas flows to the bypass passage 7 side, but the temperature of the bypass catalytic converter 8 is maintained at a certain level (for example, about 500 ° C.) by a part of exhaust that always passes. Can do. The catalytic converter is more easily poisoned as its temperature is lower. However, since the bypass catalytic converter 8 is maintained at a certain high temperature as described above, the poisoning is suppressed. Further, when the bypass valve 5 once opened is closed again, the exhaust purification action of the bypass catalytic converter 8 can be expected immediately after that.

  In addition, as poisoning in the present embodiment, so-called sulfur poisoning is assumed in which sulfur oxide (SOx) is accumulated in the bypass catalytic converter 8 to inhibit the original catalytic reaction of the catalyst. When the fuel burns, the sulfur content in the fuel is oxidized and sulfur oxides (SOx) such as SO2 and SO3 are generated. This sulfur oxide (SOx) is absorbed by the catalyst and, when time passes, forms a stable sulfate and tends to accumulate in the catalyst. As the amount of sulfur oxide (SOx) accumulated in the catalyst increases, sulfur poisoning that inhibits the original catalytic reaction of the catalyst proceeds.

  FIG. 2 is a flowchart showing a basic control flow of the poisoning release control of the bypass catalytic converter 8, and FIGS. 3 to 18 are subroutines thereof.

  In step S1, the opening / closing of the bypass valve 5 as the main passage closing means is determined (open / close determination means). In step S2, the catalyst temperature of the bypass catalytic converter 8 is determined (catalyst temperature determination means). In step S3, the poisoning amount of the bypass catalytic converter 8 is added / subtracted (a poisoning amount adding / subtracting means). In step S4, it is determined whether the poisoning amount calculated in step 3 has reached a predetermined poisoning release determination amount. In step S5, it is determined whether a predetermined engine operating condition capable of executing catalyst poisoning release control is satisfied. In step S6, poisoning release control is executed (poisoning release control means).

  FIG. 3 shows an example of the bypass valve opening / closing determination process in step S1, and it is determined in step S11 whether the bypass valve 5 is closed. Only when it is determined that the bypass valve 5 is closed, the process proceeds to the catalyst temperature determination process in step S2, and when the bypass valve 5 is open, this routine is terminated and the process returns to the start, and a predetermined calculation is performed. The next routine is performed again after an interval (for example, 10 ms). The opening / closing determination process of the bypass valve 5 is performed by a routine different from this routine. Basically, when the bypass catalytic converter 8 is determined to be inactive based on the catalyst temperature of the bypass catalytic converter 8 or the like. Closed and opened when judged active.

  FIG. 4 shows a first example of the catalyst temperature determination process in step S2. In step S21, it is determined whether or not the bypass catalyst outlet temperature RGASTTEMP is lower than a predetermined poisonable decomposable catalyst outlet temperature SOXRTEMP. Thus, by picking up the reaction heat of the catalyst, the determination based on the bypass catalyst outlet temperature RGASTTEMP having a high correlation with the catalyst BED temperature is basically used. However, in the case where the catalyst length is long and the correlation between the catalyst BED inlet surface temperature and the bypass catalyst outlet temperature RGASTTEMP cannot be satisfactorily obtained, the determination process in step S21 is performed as in the second example shown in FIG. In addition, in step S22, it is determined whether the bypass catalyst inlet temperature FGASTTEMP is lower than a predetermined poisoning releaseable catalyst inlet temperature SOXFTEMP. As described above, the determination accuracy of the bypass catalyst inlet temperature FGASTTEMP in addition to the bypass catalyst outlet temperature RGASTTEMP is also used as the catalyst temperature, so that the determination accuracy can be further improved.

  FIG. 6 shows a distance addition / subtraction method which is a first example of the poisoning amount addition / subtraction in step S3. When it is determined in step S2 that the catalyst temperature RGASTTEMP (and FGASTTEMP) is lower than the poisonable decomposable catalyst temperature SOXRTEMP (and SOXFTEMP) (2A), in step S31, the catalyst poisoning accumulated distance before one calculation The vehicle speed VSP is added to SOXMILE (old). On the other hand, if it is determined that the catalyst temperature has reached the poisoning releaseable catalyst temperature (2B), the value obtained by multiplying the vehicle speed VSP by the predetermined poisoning release equivalent vehicle speed RSMILE in step S32 is the catalyst before one calculation. Subtract from the accumulated distance during poisoning.

  FIG. 7 shows a method of adding / subtracting the sulfur passage amount at the time of catalyst poisoning, which is a second example of the poisoning amount addition / subtraction in step S3. When it is determined in step S2 that the catalyst temperature is lower than the poisoning decomposable catalyst temperature (2A), in step S33, based on the fuel injection amount QINJ per unit time, the rotational speed NMRPM, and the like, In step S34, the SOXIN is added to the total catalyst passing sulfur amount SOXCAL (old), which is an integrated value before one calculation, and the total catalyst passing sulfur amount SOXCAL is calculated and updated. To do. On the other hand, if it is determined that the catalyst temperature has reached the poisoning releaseable catalyst temperature (2B), the total catalyst passing sulfur before one calculation is calculated by multiplying the vehicle speed VSP by the poisoning release equivalent vehicle speed RSMILE in step S35. Subtract from the amount SOXCAL to calculate / update the total catalyst passing sulfur amount SOXCAL.

  Thus, in any method, addition is performed when the temperature is lower than the poisonable temperature, and subtraction is performed when the catalyst temperature exceeds the poisonable temperature, so that the total catalyst passing sulfur amount SOXCAL is obtained. Can be obtained with high accuracy.

  FIG. 8 shows an example of a determination process as to whether the poisoning release determination amount has been reached in step S4. In the case of the distance addition / subtraction method shown in FIG. 6, it is determined in step S41 whether or not the accumulated distance SOXMILE at the time of catalyst poisoning exceeds the poisoning release determination integrated distance SOXMAX as the poisoning release determination amount. The process proceeds to the operation condition determination process in step S5, and if not exceeded, this routine is terminated and the process returns to the first bypass valve open / close determination process (S1). In the method of adding and subtracting the sulfur passage amount at the time of catalyst poisoning shown in FIG. 7, in step S42, it is determined whether or not the total catalyst passage sulfur amount SOXCAL exceeds the poisoning release determination integrated value SOXFUL as the poisoning release determination amount. If it has exceeded, the process proceeds to the operation condition determination process in step S5. If not, the routine ends and the process returns to the first bypass valve open / close determination process (S1).

  FIG. 9 and FIG. 10 each show an example of a determination process of predetermined operating conditions that can execute the poisoning release control in step S5. Both examples are intended to reduce or avoid adverse effects on engine operability due to poisoning release control and to suppress or avoid excessive exhaust temperature rise by performing poisoning release control.

  In the first example of FIG. 9, it is determined whether the vehicle speed VSP, the load TP, and the rotational speed MNRPM are within predetermined ranges. Specifically, it is determined in step S51 whether the vehicle speed VSP is equal to or higher than a predetermined lower limit vehicle speed RSVSP1 and equal to or lower than a predetermined upper limit vehicle speed RSVSP2, and in step S52, the load TP is equal to or higher than a predetermined lower limit load RSTP1 and lower than a predetermined upper limit load RSTP2. In step S53, it is determined whether the rotational speed MNRPM is equal to or higher than a predetermined lower limit rotational speed RRPM1 and equal to or lower than a predetermined upper limit rotational speed RRPM2. Only when all the conditions of steps S51 to S53 are satisfied, the process proceeds to the poisoning release control of step S6. In other cases, this routine is terminated and the process returns to the first bypass valve opening / closing determination process (S1).

  In the second example of FIG. 10, it is determined whether the vehicle is decelerating for a certain time and whether fuel injection is stopped, that is, whether fuel cut is in progress. Specifically, in step S54, it is determined whether the vehicle speed change amount ΔVSP is less than 0, that is, the vehicle is decelerating. If the vehicle is not decelerating, the value of the deceleration time integration timer VSPTIMER is initialized to “0” in step S58, the present routine is terminated, and the process returns to the first bypass valve opening / closing determination process (S1). If the vehicle is decelerating, “1” is added to the deceleration time integration timer VSPTIMER in step S55, and it is determined in step S56 whether the value of the deceleration time integration timer VSPTIMER is equal to or greater than a predetermined poisoning release determination deceleration time RSTIMER. To do. In step S57, it is determined whether a fuel cut is in progress. If the deceleration time integrated value VSPTIMER is equal to or longer than the predetermined poisoning release determination deceleration time RSTIMER and the fuel cut is in progress, the process proceeds to poisoning release control in step S6, and otherwise returns to step S54.

  FIGS. 11 to 18 show examples of poisoning release control in step S6, FIGS. 11 to 14 show an unbalanced λ control system, and FIGS. 15 to 18 show an ignition timing retard and air-fuel ratio enrichment system. In any method, after the poisoning release control, the catalyst temperature RGASTTEMP (and FGASTTEMP) is monitored, and if the catalyst temperature exceeds the poisoning releaseable catalyst temperature SOXRTEMP (and SOXFTEMP) (steps S62 and S63), the poisoning is performed. The amount is subtracted (steps S64 and S64A), and the cumulative distance SOXMILE at the time of catalyst poisoning corresponding to the poisoning amount and the cumulative sulfur passage amount SOXCAL at the time of catalyst poisoning correspond to the RSEND and RSFIN corresponding to the poisoning release determination amount. , SOXFUL, or whether it is less than SOXMAX (steps S65, S65A, 65B, S65C). If the poisoning amount is less than the poisoning release determination amount, the poisoning release control is ended. Otherwise, this routine is ended and the process returns to the first bypass valve opening / closing determination process (step S1). In addition, in the subtraction of the poisoning amount in steps S64 and S64A, a value obtained by multiplying the vehicle speed VSP at that time by the equivalent vehicle speeds RSMILE and RSSOX corresponding to the poisoning release amount is subtracted. On the other hand, if the poisoning amount is less than the poisoning release determination amount, the poisoning amount is integrated (steps S67, S68), the present routine is terminated, and the process returns to the first bypass valve opening / closing determination process (step S1).

  During the poisoning release control, it is always determined whether or not a predetermined operating condition (see FIGS. 9 and 10) is satisfied. If the operating condition is not satisfied, the poisoning release control may be terminated.

  The specific poisoning release control is known as described in Japanese Patent Application Laid-Open No. 2000-337137 and the like. Briefly, in step S61 in FIGS. 11 to 14, the air-fuel ratio of each cylinder is intentionally set. In FIG. 15 to FIG. 18, in step S61, the air-fuel ratio (A / F) is richer than the stoichiometric air-fuel ratio while correcting the ignition timing to the retarded angle (retarded) side. Shift to.

  The characteristic technical ideas of the present invention that can be grasped from such embodiments will be listed together with their effects.

  [1] A main passage 3 through which exhaust exhausted from a cylinder flows, a main catalytic converter 4 interposed in the main passage 3, a branch from the main passage 3 on the upstream side of the main catalytic converter 4, and the above The bypass passage 7 having a smaller passage cross-sectional area than the main passage 3, the bypass catalytic converter 8 interposed in the bypass passage 7, and the main passage 3 so that the exhaust discharged from the cylinder flows to the bypass passage 7. Main passage closing means such as a bypass valve 5 for closing.

  When the open / close determining means (step S1) for determining whether the main passage 3 is closed by the main passage closing means and when the main passage 3 is determined to be closed by the open / close determining means, A poisoning amount addition / subtraction means (step S3) for adding and subtracting the poisoning amount of the bypass catalytic converter 8, and when the poisoning amount reaches a predetermined poisoning release determination amount and satisfies a predetermined operating condition, Poisoning release control means (step S6) for performing poisoning release control.

  In this way, the control logic is simplified and simplified by adding and subtracting the poisoning amount only when the main passage 3 is closed and the exhaust gas flows to the bypass passage 7 side where the bypass catalytic converter 8 is provided. The amount of poisoning can be accurately and accurately grasped, and when the amount of poisoning reaches a predetermined poisoning release determination amount and a predetermined operating condition is satisfied, the poisoning release control is performed. The poisoning release, that is, the regeneration of the bypass catalytic converter 8 can be performed satisfactorily. In addition, since the main passage 3 is not closed for the poisoning release control but the poisoning release control is performed only when the main passage 3 is closed, the opportunity for the poisoning release control to be performed. Can be minimized.

  [2] Preferably, as shown in FIGS. 6 and 7, the poisoning amount is added or subtracted based on the catalyst temperature of the bypass catalytic converter 8. As a result, the poisoning amount of the catalyst can be grasped more accurately, the frequency at which the poisoning release control is performed can be minimized, and the opportunity to expose the catalyst to a high temperature can be reduced / suppressed.

  [3] Specifically, catalyst temperature determination means for determining whether the catalyst temperature (RGASTTEMP, FGASTTEMP) of the bypass catalytic converter 8 is lower than a predetermined poisonable release temperature (SOXRTEMP, SOXFTEMP) (steps S21, S22). The poisoning amount addition / subtraction means adds the poisoning amount if the catalyst temperature is lower than the poisoning releaseable temperature (steps S31 and S34), and the catalyst temperature is released from the poisoning release. If the allowable temperature is exceeded, the poisoning amount is subtracted (steps S32 and S35). Thus, the poisoning amount of the catalyst can be accurately grasped by a simple control logic of comparing the catalyst temperature and the poisonable release temperature.

  [4] As shown in FIGS. 11 to 18, when the poisoning amount (SOXMILE, SOXCAL) becomes less than the poisoning release determination amount (RSEND, RSFIN, SOXFUL, SOXMAX) during the poisoning release control, The poisoning release control is terminated (steps S65, S65A, S65B, S65C). Thereby, it is possible to prevent the poisoning release control from being performed excessively.

  [5] Further, the poisoning release control may be terminated when it is outside predetermined operating conditions during the poisoning release control. As a result, it is possible to reduce or avoid the execution of excessive poisoning release control, and it is possible to reduce adverse effects on driving performance due to the poisoning release control.

Explanatory drawing which showed typically the piping layout and control system of the exhaust apparatus of an internal combustion engine. The flowchart which shows the basic flow of the poisoning cancellation | release control of the bypass catalytic converter which concerns on one Embodiment of this invention. The subroutine which shows an example of the bypass valve opening / closing determination process of FIG. The subroutine which shows the 1st example of the catalyst temperature determination process of FIG. The subroutine which shows the 2nd example of the catalyst temperature determination process of FIG. The subroutine which shows the 1st example of the poisoning addition / subtraction process of FIG. The subroutine which shows the 2nd example of the poisoning addition / subtraction process of FIG. The subroutine which shows the example of the judgment processing whether it reached the poisoning cancellation | release judgment amount of FIG. The subroutine which shows the 1st example of the determination process of the driving condition of FIG. The subroutine which shows the 2nd example of the determination process of the operating condition of FIG. The subroutine which shows the 1st example of the poisoning cancellation | release control of FIG. The subroutine which similarly shows the 1st example of the poisoning cancellation | release control of FIG. The subroutine which similarly shows the 1st example of the poisoning cancellation | release control of FIG. The subroutine which similarly shows the 1st example of the poisoning cancellation | release control of FIG. The subroutine which shows the 2nd example of the poisoning cancellation | release control of FIG. The subroutine which similarly shows the 2nd example of the poisoning cancellation | release control of FIG. The subroutine which similarly shows the 2nd example of the poisoning cancellation | release control of FIG. The subroutine which similarly shows the 2nd example of the poisoning cancellation | release control of FIG.

Explanation of symbols

3 ... Main passage 4 ... Main catalytic converter 5 ... Bypass valve 7 ... Bypass passage 8 ... Bypass catalytic converter 27 ... Engine control unit

Claims (5)

A main passage through which exhaust exhausted from the cylinder flows,
A main catalytic converter interposed in the main passage;
A bypass passage that branches off from the main passage on the upstream side of the main catalytic converter, and has a smaller passage cross-sectional area than the main passage;
A bypass catalytic converter interposed in the bypass passage;
A catalyst poisoning release control device for an internal combustion engine for a vehicle, comprising: a main passage closing means for closing the main passage so that the exhaust discharged from the cylinder flows into the bypass passage;
Open / close determining means for determining whether the main passage is closed by the main passage closing means;
Poisoning amount addition / subtraction means for adding / subtracting the poisoning amount of the bypass catalytic converter when the open / close determination means determines that the main passage is closed;
Poisoning release control means for performing poisoning release control when the poisoning amount reaches a predetermined poisoning release determination amount and satisfies a predetermined operating condition;
A catalyst poisoning release control device for an internal combustion engine for a vehicle, comprising:   2. The catalyst poisoning release control device for an internal combustion engine for a vehicle according to claim 1, wherein the poisoning amount addition / subtraction means performs addition / subtraction of the poisoning amount based on a catalyst temperature of the bypass catalytic converter. Having a catalyst temperature determination means for determining whether the catalyst temperature of the bypass catalytic converter is lower than a predetermined detoxification-removable temperature;
The poisoning amount addition / subtraction means adds the poisoning amount if the catalyst temperature is lower than the poisoning decomposable temperature, and if the catalyst temperature exceeds the poisoning decomposable temperature, the poisoning amount 3. The catalyst poisoning release control apparatus for an internal combustion engine for a vehicle according to claim 2, wherein the amount is subtracted.   4. The catalyst poisoning release control according to claim 1, wherein the catalyst poisoning release control is terminated when the poisoning amount becomes less than the poisoning release judgment amount during the poisoning release control. Release control device. The catalyst poisoning release control device according to any one of claims 1 to 4, wherein the poisoning release control is ended when the predetermined operating condition is deviated during the poisoning release control.

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