JP2016130458A - Exhaust emission control system for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress progress of sulfur poisoning of an exhaust gas purification catalyst in an exhaust emission control system for a hybrid vehicle.SOLUTION: An exhaust emission control system includes an exhaust gas purification catalyst arranged in an exhaust passage of an internal combustion engine, and a control device for controlling driving of the internal combustion engine and an electric motor, and the control device performs sulfur removing control for removing sulfur oxide from the exhaust gas purification catalyst by controlling at least one of driving of the internal combustion engine and an air-fuel ratio in the exhaust passage when the sulfur oxide SOx adsorbed on the exhaust purification catalyst exceeds a prescribed amount. When the sulfur oxide adsorbed on the exhaust purification catalyst exceeds the prescribed amount C1, a start threshold Pon1 of a load for starting the internal combustion engine is set to be higher than in the case where the sulfur oxide adsorbed on the exhaust purification catalyst is equal to or less than the prescribed amount C1.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an exhaust gas purification control system for a hybrid vehicle.

  Conventionally, a hybrid vehicle including an internal combustion engine and an electric motor as a vehicle drive source is widely known. In the hybrid vehicle, driving of the internal combustion engine and the electric motor is controlled.

  On the other hand, in an internal combustion engine, an exhaust purification catalyst that absorbs NOx is arranged in an exhaust passage, and NOx in exhaust gas is absorbed by the exhaust purification catalyst and then reduced to remove NOx from the exhaust gas. The exhaust gas contains sulfur oxides SOx produced by burning sulfur components contained in the fuel. This sulfur oxide SOx is also accumulated in the exhaust purification catalyst and hinders NOx purification. This is called “sulfur poisoning”. Therefore, it is considered to perform sulfur removal control for removing SOx containing sulfur components from the exhaust purification catalyst.

  In Patent Document 1, fuel is added to an exhaust passage of an internal combustion engine to obtain a rich air-fuel ratio exhaust gas, and the ambient temperature of the exhaust purification catalyst is raised to remove SOx adsorbed on the exhaust purification catalyst. It is described.

  Patent Document 2 describes that when the SOx accumulated in the exhaust purification catalyst exceeds a predetermined amount, a request to increase the temperature of the exhaust purification catalyst is generated. When this request occurs, when the output of the internal combustion engine decreases due to a decrease in the output required for the vehicle and the exhaust temperature decreases, the internal combustion engine is stopped and the vehicle is driven by the electric motor. . With such a configuration, it is supposed that the internal combustion engine is prevented from operating in a situation where the exhaust gas temperature is low, and the temperature drop of the catalyst can be suppressed.

JP 2004-176632 A JP 2005-133563 A

  In any of the configurations described in Patent Documents 1 and 2, there is a possibility that the frequency at which the internal combustion engine is started becomes high during low-load running where the output required for the vehicle is low. As a result, the frequency at which the internal combustion engine is operated at a low load increases, and the temperature of the exhaust purification catalyst is unlikely to increase during the operation. When exhaust gas is sent to the exhaust purification catalyst having a low temperature, SOx in the exhaust gas tends to remain adsorbed on the exhaust purification catalyst. Thus, there is room for improvement in terms of suppressing the progress of sulfur poisoning of the exhaust purification catalyst.

  An object of the present invention is to provide an exhaust purification control system for a hybrid vehicle that can suppress the progress of sulfur poisoning of an exhaust purification catalyst.

  An exhaust purification control system for a hybrid vehicle according to the present invention is an exhaust purification control system for a hybrid vehicle including an internal combustion engine and a motor as a drive source for the vehicle, and an exhaust purification catalyst disposed in an exhaust passage of the internal combustion engine; A control device that controls the drive of the internal combustion engine and the motor, and the control device controls at least one of the drive of the internal combustion engine and the air-fuel ratio in the exhaust passage to thereby provide the exhaust purification catalyst. When the sulfur oxide adsorbed exceeds a predetermined amount, the sulfur removal control for removing the sulfur oxide from the exhaust purification catalyst is performed, and when the sulfur oxide adsorbed on the exhaust purification catalyst exceeds a predetermined amount, The starting threshold for the load for starting the internal combustion engine is set higher than when the sulfur oxide adsorbed on the exhaust purification catalyst is below a predetermined amount.

  According to the exhaust gas purification control system for a hybrid vehicle according to the present invention, when performing sulfur removal control for removing sulfur oxide from the exhaust purification catalyst, the internal combustion engine in a low load region in which sulfur oxide is difficult to remove from the exhaust purification catalyst. Since the operation of the engine can be suppressed, the progress of sulfur poisoning of the exhaust purification catalyst can be suppressed.

1 is a schematic configuration diagram of a hybrid vehicle including an exhaust purification control system of an embodiment according to the present invention. It is a flowchart which shows the process which controls the drive of an internal combustion engine in the case of performing sulfur removal control by the exhaust gas purification control system of embodiment. It is a figure which shows the relationship between a catalyst estimated temperature and the amount of adjustment of the adsorption amount of sulfur oxide SOx to a catalyst. It is a figure which shows two examples of the change of a vehicle request | requirement driving force and an engine speed.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. Below, the same code | symbol is attached | subjected and demonstrated to the same structure. Hereinafter, in the exhaust purification control system, a case where each of the electric motor and the generator has both functions of the electric motor and the generator will be described. The electric motor and the generator may each have a function of only the electric motor and only the generator.

  FIG. 1 is a schematic configuration diagram of a hybrid vehicle 10 including an exhaust purification control system 12 according to an embodiment of the present invention. The hybrid vehicle 10 includes an electric motor 13 and an internal combustion engine 20 as a vehicle drive source. The electric motor 13 also has a function as a generator that generates regenerative power when the vehicle is braked. Hereinafter, the internal combustion engine 20 is referred to as the engine 20.

  The hybrid vehicle 10 includes an exhaust purification control system 12, wheels 40, and a power transmission mechanism 41. The exhaust purification control system 12 includes an engine 20, an electric motor 13, a first inverter 14, a battery 15, a generator 16, a second inverter 17, and a control device 30.

  The engine 20 is a gasoline engine, and includes an engine body 22 having a plurality of cylinders 21 and an intake passage and an exhaust passage 23 (not shown) connected to the engine body 22. For example, in a four-cylinder engine, the engine 20 has a cylinder 21 that is four cylinders. The engine 20 is an in-cylinder direct injection type in which fuel is directly injected from a fuel injection valve 24 into a combustion chamber above the cylinder 21. The engine 20 may be of a port injection type that injects fuel from a fuel injection valve to an intake port (not shown) of the engine body 22.

  In the middle of the exhaust passage 23, an exhaust purification catalyst 25 that is an NOx storage reduction catalyst is disposed. Hereinafter, the exhaust purification catalyst 25 is simply referred to as the catalyst 25. The catalyst 25 stores NOx in the exhaust gas when the oxygen concentration of the inflowing exhaust gas is high, and reduces the stored NOx when the oxygen concentration of the inflowing exhaust gas decreases and there is a reducing agent.

  In the exhaust gas, there is sulfur oxide SOx generated by burning sulfur components contained in the fuel, and the SOx is adsorbed by the catalyst 25. When SOx is adsorbed on the catalyst 25, NOx occlusion is suppressed. Therefore, the control device 30 to be described later performs sulfur removal control to be described later for removing SOx from the catalyst 25 when the SOx adsorbed on the catalyst 25 is a predetermined amount or more.

  The power of the engine 20 is transmitted to the wheels 40 by the power transmission mechanism 41. The power transmission mechanism 41 includes a power split mechanism 42, an output shaft 43, a speed reduction mechanism 44, and an axle 45.

  The power split mechanism 42 is configured by a planetary gear mechanism, and includes a sun gear, a ring gear, and a plurality of pinion gears. The sun gear is connected to a rotating shaft of a generator 16 which will be described later. The plurality of pinion gears mesh with the ring gear and the sun gear, and are connected to the drive shaft 20a of the engine 20 via a carrier. The ring gear is connected to the rotating shaft 13 a of the electric motor 13 through the output shaft 43. The output shaft 43 is connected to the axle 45 via the speed reduction mechanism 44. The axle 45 is connected to wheels 40 disposed on the left and right sides of the vehicle (upper and lower sides in FIG. 1). Thus, the power split mechanism 42 splits the power from the engine 20 into a route to the wheel 40 side and a route to the generator 16.

  The electric motor 13 is connected to the battery 15 via the first inverter 14. The battery 15 supplies power to the electric motor 13. The generator 16 is connected to the battery 15 via the second inverter 17. The generator 16 is driven by the power of the engine 20 to generate power, and supplies power to the battery 15 to charge the battery 15. The generator 16 also has a function as a starting electric motor that starts the engine 20.

  In the hybrid vehicle 10, the vehicle 45 travels by driving the wheels 40 by rotating the axle 45 by the output of the engine 20 or the electric motor 13 during normal travel. In the hybrid vehicle 10, the vehicle 45 can be driven by driving the wheels 40 by rotating the axle 45 with the outputs of both the engine 20 and the electric motor 13.

  The control device 30 includes a microcomputer having a CPU and a memory. The control device 30 controls driving of the engine 20. The control device 30 also controls driving of the electric motor 13 via the first inverter 14 and also controls driving of the generator 16 via the second inverter 17.

  The control device 30 calculates the required vehicle driving force for the axle 45 to which the wheels 40 are connected, according to the amount of depression of an accelerator pedal (not shown) and the vehicle speed detected by a vehicle speed sensor (not shown).

  In addition, control device 30 calculates and acquires SOC (State of Charge), which is a charging rate of battery 15, using a current sensor (not shown) that detects charging / discharging current of battery 15. Control device 30 permits starting of engine 20 when the obtained value of SOC is less than the predetermined SOC value, and prohibits starting of engine 20 when the obtained value of SOC is equal to or greater than the predetermined SOC value. When starting of the engine 20 is prohibited, the control device 30 performs an intermittent stop that temporarily stops the engine 20. When the vehicle travels during the execution of the intermittent stop, the control device 30 controls the electric motor 13 so as to realize the vehicle required driving force by driving the electric motor 13.

  Further, detection signals are input to the control device 30 from the air flow meter 50 and the rotation speed sensor 51. The air flow meter 50 is provided in the intake passage and detects an intake air flow rate flowing through the intake passage. The rotation speed sensor 51 detects the rotation speed N of the engine 20. The control device 30 detects the engine load from the intake air flow rate detected by the air flow meter 50 and the rotational speed N of the engine 20 detected by the rotational speed sensor 51. Here, “engine load” means charging efficiency (%) of intake air in the engine 20. The control device 30 also receives a detection signal of a throttle opening sensor that detects a throttle opening W of a throttle valve (not shown) provided in the intake passage. The engine load may be calculated from only the detected value of the rotational speed N of the engine 20 and the throttle opening W, or the detected value of the throttle opening W.

  A detection signal from the air-fuel ratio sensor 52 is also input to the control device 30. The air-fuel ratio sensor 52 detects an air-fuel ratio A / F that is a ratio of air and fuel in the exhaust gas that is provided in the exhaust passage 23 and flows into the catalyst 25.

  The control device 30 controls the driving of the engine 20 and the electric motor 13 so as to realize the vehicle required driving force.

  Further, the control device 30 performs sulfur removal control for removing SOx from the catalyst 25 when the estimated value M of the adsorption amount of the sulfur oxide SOx on the catalyst 25 exceeds a predetermined amount C1 (M> C1). It should be noted that “removing SOx” is sufficient if SOx can be reduced from the catalyst 25, and includes a case where only a part of SOx is removed from the catalyst 25. The sulfur removal control is also referred to as “poisoning recovery process”. The sulfur removal control is performed by raising the temperature of the catalyst 25 and lowering the oxygen concentration by setting the air-fuel ratio A / F of the exhaust gas flowing through the exhaust passage 23 to the rich side where the fuel is excessive. For example, the control device 30 drives the engine 20 so as to retard the ignition timing of a spark plug (not shown) in the combustion chamber above the cylinder 21 or retard the timing of fuel injection at the fuel injection valve 24. Is controlled to raise the temperature of the exhaust gas and raise the temperature of the catalyst 25. Further, the control device 30 may control the driving of the engine 20 so that the engine 20 generates an output that is equal to or higher than the vehicle required driving force. Then, a portion of the engine output that exceeds the vehicle required driving force may be recovered as generated power by the generator 16 to charge the battery 15. Thereby, the temperature of the catalyst 25 can be raised by increasing the load of the engine 20 and raising the temperature of the engine 20.

  Further, in order to make the air-fuel ratio A / F of the exhaust gas rich, operation is performed with the air-fuel ratio A / F in the combustion chamber being richer than the stoichiometric air-fuel ratio, or fuel (not shown) in the exhaust gas The air-fuel ratio A / F in the exhaust passage 23 can be controlled so as to add fuel from the addition valve.

  In the sulfur removal control, only one of the control for raising the temperature of the catalyst 25 and the control for setting the air-fuel ratio of the exhaust gas to the rich side may be performed. For example, SOx may be removed from the catalyst 25 only by raising the temperature of the catalyst 25.

  Further, the control device 30 estimates an estimated value M of the amount of SOx adsorbed on the catalyst 25 as described later. The estimated value M represents the poisoning level of the catalyst 25. The higher the estimated value M, the higher the poisoning level. When the estimated value M exceeds the predetermined amount C1, the control device 30 sets the start threshold value related to the vehicle required driving force for the load, which starts the engine 20, as the first start threshold value Pon1. Further, the control device 30 sets the start threshold value of the engine 20 when the estimated value M of the SOx adsorption amount to the catalyst 25 is equal to or less than the predetermined amount C1 (M ≦ C1) as the second start threshold value Pon2. The first start threshold Pon1 is set higher than the second start threshold Pon2 (Pon1> Pon2). The start threshold values Pon1 and Pon2 are threshold values used by the control device 30 to determine whether or not the engine 20 needs to be started with the required driving force of the vehicle. The control device 30 starts the engine 20 when the required driving force of the vehicle is equal to or higher than the corresponding start threshold values Pon1, Pon2.

  Further, the control device 30 sets the stop threshold value of the engine 20 as the first stop threshold value Poff1 when the estimated value M of the adsorption amount of SOx on the catalyst 25 exceeds the predetermined amount C1. In addition, when the estimated value M of the adsorption amount of SOx on the catalyst 25 is equal to or less than the predetermined amount C1 (M ≦ C1), the control device 30 starts the engine 20 and sets a stop threshold value related to the vehicle required driving force for the load. The second stop threshold value Poff2 is set. The first stop threshold value Poff1 is set higher than the second stop threshold value Poff2 (Poff1> Poff2). The stop threshold values Poff1 and Poff2 are threshold values used by the control device 30 to determine whether or not the engine 20 needs to be stopped with the required driving force of the vehicle. The control device 30 stops the engine 20 when the required driving force of the vehicle is equal to or less than the corresponding stop threshold values Poff1, Poff2.

  Note that the second start threshold Pon2 and the second stop threshold Poff2 may be set as follows. For example, the fuel consumption of the engine 20 when the electric motor 13 is driven by the electric power generated by the generator 16 by driving the engine 20 and the battery 15 is charged to realize the required driving force of the vehicle is the first fuel consumption. And Further, the fuel consumption when the required driving force of the vehicle is realized by driving the engine 20 is defined as the second fuel consumption. Then, the second start threshold value Pon2 and the second stop threshold value are set so that the minimum fuel consumption amount is obtained by comparing the first fuel consumption amount and the second fuel consumption amount, that is, the fuel consumption amount is optimized. Poff2 may be set.

  Next, a process for controlling the driving of the engine 20 by the exhaust purification control system 12 will be described with reference to FIG. FIG. 2 is a flowchart showing a process for controlling the driving of the engine 20 when the exhaust purification control system 12 of the embodiment performs the sulfur removal control.

  In step S10 of FIG. 2, as described above, control device 30 determines whether or not starting of engine 20 is permitted from the obtained value of the SOC. Hereinafter, step S is simply referred to as S. If the determination result in S10 is affirmative, that is, YES, in S11, the control device 30 determines whether or not the estimated value M of the adsorption amount of SOx to the catalyst 25 exceeds a predetermined amount C1 (M> C1). To do.

  The estimated value M of the SOx adsorption amount is calculated from the detection value of the air flow meter 50 and the detection value of the air-fuel ratio sensor 52. Specifically, the fuel injection amount to be injected is determined from the intake air flow rate detected by the air flow meter 50, and the fuel amount in the exhaust gas is calculated from the injection amount. The greater the amount of fuel, the greater the amount of SOx. The estimated value M of the SOx adsorption amount is calculated from the calculated fuel amount, the predicted temperature of the catalyst 25, and the detected value of the air-fuel ratio. Here, the predicted temperature of the catalyst 25 is estimated by using a relational expression set in advance from the rotational speed N of the engine 20 detected by the rotational speed sensor 51 and the engine load (%).

  FIG. 3 shows the relationship between the predicted temperature of the catalyst 25 and the amount of SOx adsorbed on the catalyst 25. As shown in FIG. 3, the amount of SOx added to or subtracted from the catalyst 25 is calculated from a predetermined value D1 for adjustment and the predicted temperature of the catalyst 25. Specifically, when the predicted temperature of the catalyst 25 is less than the predetermined value D1 for adjustment, the adsorption amount of SOx is calculated from a predetermined relational expression according to the fuel amount calculated above. In this calculation, the amount of SOx adsorbed increases as the amount of fuel increases. Here, the predetermined value D1 for adjustment is changed according to the air-fuel ratio A / F detected by the air-fuel ratio sensor 52. If the air-fuel ratio A / F is high, that is, if the air-fuel ratio A / F of the exhaust gas is on the lean side with respect to the target air-fuel ratio, SOx is likely to be adsorbed by the catalyst 25, so the predetermined value D1 for adjustment is high. Become. When the air-fuel ratio A / F is low, that is, when the air-fuel ratio A / F of the exhaust gas is rich with respect to the target air-fuel ratio, SOx is hardly adsorbed by the catalyst 25, so the predetermined value D1 for adjustment is low.

  Further, if the predicted temperature of the catalyst 25 is equal to or greater than the predetermined value D1 for adjustment, the adsorption amount of SOx is subtracted as the predicted temperature of the catalyst 25 increases. In this calculation, the higher the predicted temperature of the catalyst 25, the larger the subtraction amount of the SOx adsorption amount. The relationship between the subtraction amount of the SOx adsorption amount with respect to the predicted temperature of the catalyst 25 and the addition amount of SOx according to the fuel amount is set in advance by experiments or the like. The calculation of the amount of SOx added to or subtracted from the catalyst 25 is performed every predetermined time or when a predetermined condition is satisfied. As a result, the estimated value M is calculated as the amount of SOx adsorbed on the current catalyst 25.

  Returning to FIG. 2, when the estimated value M of the SOx adsorption amount exceeds the predetermined amount C1 in the determination of S11 (M> C1), sulfur removal control for removing SOx from the catalyst 25 is performed. In S12, the control device 30 sets the start threshold value of the engine 20 to the first start threshold value Pon1, and sets the stop threshold value of the engine 20 to the first stop threshold value Poff1. The first starting threshold value Pon1 is higher than the second starting threshold value Pon2 set when the estimated value M of the adsorption amount of SOx to the catalyst 25 is equal to or less than the predetermined amount C1 (M ≦ C1) (Pon1> Pon2). The first stop threshold value Poff1 is higher than the second stop threshold value Poff2 that is set when the estimated value M of the adsorption amount of SOx to the catalyst 25 is equal to or less than the predetermined amount C1 (Poff1> Poff2).

  On the other hand, when the estimated value M is equal to or smaller than the predetermined amount C1 in the determination of S11, in S13, the control device 30 sets the start threshold value of the engine 20 to the second start threshold value Pon2 lower than Pon1, and the engine 20 stop threshold value. Is set to a second stop threshold Poff2 lower than Poff1.

  Then, after the start threshold value and the engine 20 stop threshold value are set in S12 or S13, the control device 30 starts and stops the engine 20 from the vehicle required driving force and the start threshold value and stop threshold value of the engine 20 in S14. To control. Further, the control device 30 controls the driving of the electric motor 13 according to the vehicle required driving force and the driving state of the engine 20. For example, when the required vehicle driving force cannot be realized only by the output of the engine 20, the shortage of the required vehicle driving force is compensated by driving the electric motor 13.

  On the other hand, if the determination result in S10 is negative, that is, if it is NO, the start of the engine 20 is prohibited in S15, and the required driving force of the vehicle is realized by driving the electric motor 13. After the processes of S14 and S15, the process returns to S10 and the process is repeated.

  In addition, the estimation method of the adsorption amount of SOx on the catalyst 25 is not limited to the method described above, and various methods can be adopted.

  According to the exhaust purification control system 12 described above, when the sulfur removal control of the catalyst 25 is performed, the operation of the engine 20 in a low load region where SOx is difficult to be removed from the catalyst 25 can be suppressed. As a result, the chance of exhaust gas being sent to the catalyst 25 in a situation where the temperature of the catalyst 25 is low can be reduced, and the progress of sulfur poisoning of the catalyst 25 can be suppressed.

  FIG. 4 is a diagram illustrating two examples of changes in the vehicle required driving force and the rotational speed of the engine 20. First, consider a case in which the vehicle required driving force changes as indicated by a one-dot chain line α1 when the driver depresses the accelerator pedal at time t1 in a normal time when the sulfur removal control is not performed. In the change of the alternate long and short dash line α1, the vehicle required driving force becomes equal to or greater than the second start threshold value Pon2 at time t2, and the engine 20 starts. Then, the engine speed increases from time t2 as indicated by a one-dot chain line β1.

  Further, the vehicle required driving force becomes equal to or less than the second stop threshold value Poff2 at time t3, the engine speed indicated by β1 rapidly decreases, and the engine 20 stops at time t4.

  On the other hand, in the case where the sulfur removal control is performed when the estimated value M of the SOx adsorption amount on the catalyst 25 is equal to or greater than the predetermined amount C1, the vehicle required driving force changes as indicated by the alternate long and short dash line α1. The required driving force does not exceed the first start threshold value Pon1. As a result, the engine 20 is not started. At this time, the vehicle required driving force is realized by driving the electric motor 13, and the vehicle performs EV traveling that travels by driving the electric motor 13 without driving the engine 20.

  Further, in the case where the sulfur removal control is performed, when the vehicle required driving force increases as shown by the solid line α2 in FIG. 4, when the vehicle required driving force becomes equal to or greater than the first start threshold value Pon1 at time t2, the engine 20 Start. Then, the engine speed increases from time t2 as indicated by a solid line β2. At time t6, the vehicle required driving force becomes equal to or less than the first stop threshold value Poff1, the engine speed indicated by β2 decreases rapidly, and the engine 20 stops at time t7.

  When the sulfur removal control is performed in this way, the starting threshold value of the engine 20 becomes as high as the first starting threshold value Pon1, so that the engine 20 is operated at a low load when the required driving force of the vehicle changes along the one-dot chain line α1 in FIG. Not started. At such a low load, the temperature of the catalyst 25 is difficult to rise, and SOx is easily adsorbed on the catalyst 25. As a result, starting of the engine 20 in a state in which SOx is easily adsorbed by the catalyst 25 is suppressed, that is, the operation opportunity of the engine 20 at a low load can be reduced. Therefore, the situation where SOx is easily adsorbed on the catalyst 25 can be reduced, and the progress of sulfur poisoning of the catalyst 25 can be suppressed.

  As a method for raising the temperature of the catalyst 25, the output of the engine 20 is increased to the required driving force of the vehicle or more, and the portion of the output of the engine 20 exceeding the required driving force is converted into the generated power of the generator 16. It is also conceivable to charge the battery 15. From this, as a comparative example, the engine 20 has a start threshold value that is the same as the normal start threshold value when no sulfur removal control is performed, and the engine 25 increases the temperature of the catalyst 25 when the vehicle required driving force is low. It is also conceivable to perform control to further increase the output of 20. On the other hand, in this configuration, it is necessary to considerably increase the output of the engine 20 in order to raise the required temperature of the catalyst 25 at a low load where the vehicle required driving force is low. As a result, there is a possibility that the charging power to the battery 15 may become considerably high. However, since the chargeable power of the battery 15 is limited, there is also a limit to an increase in the output of the engine 20. Accordingly, there is a possibility that the catalyst 25 cannot be sufficiently heated up to a temperature at which sulfur is desorbed. In the embodiment, when the load is low, the engine 20 is not driven, and the vehicle performs EV traveling. Therefore, the situation in which the engine 20 is operated at a low temperature of the catalyst 25 can be reduced.

  In the embodiment, when the SOx adsorbed on the catalyst 25 exceeds a predetermined amount, the stop threshold of the engine 20 is set to a first stop threshold Poff1 that is higher than that in the case where the SOx adsorbed on the catalyst 25 is equal to or less than the predetermined amount. Has been. Thereby, the situation where the engine 20 is operated with a low load can be reduced. For this reason, the progress of sulfur poisoning of the catalyst 25 can be further suppressed.

  As another example of the embodiment, when the SOx adsorbed on the catalyst 25 exceeds a predetermined amount, the stop threshold of the engine 20 is set, and the stop threshold of the engine 20 when the SOx adsorbed amount on the catalyst 25 is equal to or less than the predetermined amount. It is good also as a structure made into. Even in this configuration, the start threshold value of the engine 20 when performing sulfur removal control is increased, so that the progress of sulfur poisoning of the catalyst 25 can be suppressed.

  DESCRIPTION OF SYMBOLS 10 Hybrid vehicle, 12 Exhaust gas purification control system, 13 Electric motor, 13a Rotating shaft, 14 1st inverter, 15 Battery, 16 Generator, 17 2nd inverter, 20 Internal combustion engine (engine), 20a Drive shaft, 21 Cylinder, 22 Engine body, 23 Exhaust passage, 24 Fuel injection valve, 25 Exhaust purification catalyst (catalyst), 30 Control device, 40 Wheel, 41 Power transmission mechanism, 42 Power split mechanism, 43 Output shaft, 44 Deceleration mechanism, 45 Axle, 50 Air flow Meter, 51 RPM sensor, 52 Air-fuel ratio sensor.

Claims (1)

An exhaust purification control system for a hybrid vehicle comprising an internal combustion engine and an electric motor as a vehicle drive source,
An exhaust purification catalyst disposed in an exhaust passage of the internal combustion engine;
A control device for controlling the driving of the internal combustion engine and the motor,
The control device controls at least one of the driving of the internal combustion engine and the air-fuel ratio in the exhaust passage so that when the sulfur oxide adsorbed on the exhaust purification catalyst exceeds a predetermined amount, the control device removes from the exhaust purification catalyst. While performing sulfur removal control to remove the sulfur oxide,
A start threshold for a load that starts the internal combustion engine when the sulfur oxide adsorbed on the exhaust purification catalyst exceeds a predetermined amount compared to a case where the sulfur oxide adsorbed on the exhaust purification catalyst is less than a predetermined amount High exhaust emission control system for hybrid vehicles.

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