JP2006266115A - Exhaust emission control device for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply reducing agent to an exhaust emission control catalyst when the same is required without newly providing an exclusive device in relation to an exhaust emission control device for a hybrid vehicle. <P>SOLUTION: Supply timing of reducing agent to an exhaust emission control catalyst provided in an exhaust gas passage is determined. When it is determined based on the determination result that it is time to supply reducing agent, an internal combustion engine is forcedly rotated by a motor under a condition where combustion of the internal combustion engine is stopped. Simultaneously, reducing agent is supplied to an intake air passage or a combustion chamber of the internal combustion engine. The supplied reducing agent is fed to the exhaust gas passage by pumping action when the internal combustion engine is forcedly rotated by the motor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust emission control device for a hybrid vehicle having an internal combustion engine and a motor and capable of driving the vehicle by at least the motor.

  An internal combustion engine that can be operated at an air-fuel ratio leaner than the stoichiometric air-fuel ratio, a so-called lean burn engine is known. The exhaust gas discharged from the lean burn engine has a feature that the concentration of NOx is higher than that of HC and CO, and NOx in the exhaust gas cannot be sufficiently purified only by the three-way catalyst. For this reason, a NOx catalyst capable of storing NOx is provided in the exhaust passage of the lean burn engine together with or instead of the three-way catalyst.

However, the NOx storage capacity of the NOx catalyst is limited. For this reason, when the storage capacity of the NOx catalyst approaches the limit, it is necessary to release the stored NOx and restore the storage capacity. In order to release NOx from the NOx catalyst, the NOx catalyst may be brought into a reducing atmosphere by adding a reducing agent to the exhaust gas. NOx occluded in the NOx catalyst is reduced by the reducing agent, becomes harmless nitrogen, and is released into the atmosphere. As the reducing agent, hydrogen is used in addition to engine fuel (for example, gasoline). Hydrogen has a high reducing ability at low temperatures and is excellent as a reducing agent. Patent Document 1 discloses a system in which a hydrogen tank is connected upstream of a NOx catalyst in an exhaust passage and hydrogen is directly supplied to the exhaust passage.
Japanese translation of PCT publication No. 2003-507631 JP-A-6-137135 JP 2002-303129 A

  However, in the technique described in Patent Document 1, it is necessary to newly provide a dedicated part for supplying hydrogen to the exhaust passage, such as a valve and a pipe. Moreover, since the pressure in the exhaust passage is high, a pump for feeding hydrogen into the exhaust passage may be necessary depending on the pressure of the hydrogen supply source. In order to suppress the increase in cost and the deterioration of mountability due to the increase in the number of parts, we want to be able to supply hydrogen using existing systems as much as possible.

  In the case of an internal combustion engine that can use hydrogen as a fuel, for example, unburned hydrogen can be supplied to the catalyst by increasing the injection amount of hydrogen so that the air-fuel ratio becomes rich. However, in this case, there is a possibility that the torque of the internal combustion engine is fluctuated due to a change in the air-fuel ratio, and it is not always possible to supply hydrogen to the NOx catalyst when necessary. Further, hydrogen that can be used as the reducing agent is a part of the injected hydrogen, and it is necessary to inject more hydrogen than is necessary for the reduction treatment of the NOx catalyst. That is, fuel consumption may be deteriorated due to unnecessary hydrogen injection.

  The present invention has been made to solve the above-described problems, and can be performed when it is necessary to supply a reducing agent to the exhaust purification catalyst, and can be performed without newly providing a dedicated device. An object of the present invention is to provide an exhaust emission control device for a hybrid vehicle.

In order to achieve the above object, a first invention is an exhaust emission control device for a hybrid vehicle having an internal combustion engine and a motor and capable of driving a vehicle by at least the motor,
An exhaust purification catalyst provided in an exhaust passage of the internal combustion engine;
Reducing agent supply means for supplying a reducing agent into the intake passage or combustion chamber of the internal combustion engine;
When the supply timing of the reducing agent to the exhaust purification catalyst is determined and it is determined from the determination result that it is time to supply the reducing agent, the motor performs the above-described operation in a state where combustion of the internal combustion engine is stopped. Control means for forcibly rotating the internal combustion engine and operating the reducing agent supply means to supply the reducing agent;
It is characterized by having.

In a second aspect based on the first aspect, the reducing agent supply means is configured to supply hydrogen as a reducing agent.
The control means is characterized in that the start time of the internal combustion engine is set as the supply timing of hydrogen to the exhaust purification catalyst.

  In a third aspect based on the second aspect, the control means controls the opening of the throttle so that the air-fuel ratio of the air-fuel mixture containing hydrogen supplied to the exhaust purification catalyst becomes a predetermined air-fuel ratio. It is characterized by.

In order to achieve the above object, a fourth invention is an exhaust purification device for a hybrid vehicle having an internal combustion engine and a motor, and capable of driving the vehicle by at least the motor,
An exhaust purification catalyst provided in an exhaust passage of the internal combustion engine;
Reducing agent supply means for supplying a reducing agent into the intake passage or combustion chamber of the internal combustion engine;
The supply timing of the reducing agent to the exhaust purification catalyst is determined, and when it is determined that it is time to supply the reducing agent, the combustion of the internal combustion engine is stopped and the rotation of the internal combustion engine is stopped. Prior to the operation, the cylinder that stops last through the exhaust stroke is predicted, and the reducing agent is supplied from the reducing agent supply means to the cylinder so that the reducing agent is discharged from the cylinder in the final exhaust stroke of the cylinder. It is characterized by.

  According to the first invention, the reducing agent supplied to the intake passage or the combustion chamber of the internal combustion engine can be sent to the exhaust passage by the pump action when the internal combustion engine is forcibly rotated by the motor. An existing reducing agent supply means can be used as the means for supplying the reducing agent. That is, it is not necessary to provide a dedicated device for supplying the reducing agent to the exhaust purification catalyst. Moreover, according to the first aspect of the invention, the motor can travel even when the combustion of the internal combustion engine is stopped, so that it is possible to supply the reducing agent to the exhaust purification catalyst when necessary.

  Further, according to the second aspect of the invention, the exhaust purification catalyst can be warmed up by the reaction heat due to the combustion reaction of hydrogen and oxygen on the exhaust purification catalyst prior to the start of the internal combustion engine. Furthermore, according to the third invention, the combustion reaction of hydrogen and oxygen on the exhaust purification catalyst can be promoted by adjusting the air-fuel ratio, and the exhaust purification catalyst can be warmed up efficiently.

  According to the fourth invention, the reducing agent supplied to the intake passage or the combustion chamber of the internal combustion engine can be sent to the exhaust passage by utilizing the pump action of the internal combustion engine during rotation due to inertia. An existing reducing agent supply means can be used as the means for supplying the reducing agent. In addition, since the reducing agent is supplied to the cylinder that finally stops after the exhaust stroke, the reducing agent can be prevented from being diluted with air, and a rich reducing atmosphere can be created with a small amount of reducing agent.

Embodiment 1 FIG.
Hereinafter, the first embodiment of the present invention will be described with reference to FIGS. 1 and 2.
FIG. 1 is a diagram showing a configuration of a drive system for a hybrid vehicle to which an exhaust emission control device of the present invention is applied. As shown in FIG. 1, the hybrid vehicle drive system according to the present embodiment includes an internal combustion engine (hereinafter referred to as an engine) 2 and a motor 10 as power units.

  The engine 2 is configured as a hydrogen-based internal combustion engine that can use gasoline and hydrogen as fuel. The intake manifold 2 a of the engine 2 is provided with a gasoline injector 42 and a hydrogen injector 44. The gasoline injector 42 is connected to the gasoline tank 32, and the hydrogen injector 44 is connected to the hydrogen tank 34. Although these injectors 42 and 44 are provided for each cylinder, only one is shown in FIG. An exhaust pipe 4 is connected to the exhaust manifold 2 b of the engine 2. The exhaust pipe 4 is provided with a catalyst device 6 and a muffler 8 in order from the upstream side. The catalyst device 6 houses a three-way catalyst 6a and an NOx catalyst 6b which are exhaust purification catalysts.

  The drive system also includes a generator 12 that generates electric power upon receiving a drive force. The engine 2, the motor 10, and the generator 12 are connected to each other via a power split mechanism 14. A reduction gear 16 is connected to the rotating shaft of the motor 10 connected to the power split mechanism 14. The speed reducer 16 connects the rotation shaft of the motor 10 and a drive shaft 18 connected to the drive wheels 20. The power split mechanism 14 is a device that splits the driving force of the engine 2 into the generator 12 side and the speed reducer 16 side. The distribution of the driving force by the power split mechanism 14 can be arbitrarily changed.

  The drive system further includes an inverter 24, a converter 26, a high voltage battery 28, and an ECU (Electronic Control Unit) 40. The inverter 24 is connected to the generator 12 and the motor 10, and is also connected to the high voltage battery 28 via the converter 26. The electric power generated by the generator 12 can be supplied to the motor 10 via the inverter 24, or the high voltage battery 28 can be charged via the inverter 24 and the converter 26. Further, the electric power charged in the high voltage battery 28 can be supplied to the motor 10 via the converter 26 and the inverter 24. Control of the inverter 24 and the converter 26 is performed by the ECU 40. The ECU 40 comprehensively controls the entire drive system including the engine 24, the motor 10, the generator 12, the power split mechanism 14, and the like in addition to the inverter 24 and the converter 26.

  According to this drive system, the motor 10 can be stopped and the driving wheel 20 can be rotated only by the driving force of the engine 2. Conversely, the engine 2 is stopped and the driving wheel 20 can be driven only by the driving force of the motor 10. Can also be rotated. It is also possible to operate both the motor 10 and the engine 2 and rotate the driving wheels 20 by both driving forces. Further, according to this drive system, the motor 10 can also function as a starter of the engine 2. That is, when the engine 2 is started, the engine 2 can be cranked by inputting a part or all of the driving force of the motor 10 to the engine 2 via the power split mechanism 14. Further, the stopped engine 2 can be forcibly rotated as necessary regardless of the start of the engine 2.

  Further, according to this drive system, the engine 2 can be operated in the most efficient operation region by cooperatively controlling the engine 2 and the motor 10. At that time, super lean burn operation is performed by adding hydrogen, which is excellent in combustibility, to gasoline. The super lean burn operation is an operation that is performed at an air-fuel ratio that is much leaner than the stoichiometric air-fuel ratio, and can achieve remarkable effects such as improved fuel consumption and reduced NOx generation. However, during the super lean burn operation, although the absolute amount of NOx generated in the engine 2 decreases, the ratio of the generated amount of NOx to the generated amount of HC and CO increases. For this reason, NOx in the exhaust gas cannot be sufficiently purified only by the three-way catalyst 6a. In this drive system, NOx generated during the super lean burn operation is occluded by the NOx catalyst 6b, thereby preventing NOx from being released into the atmosphere.

  In such a system using the NOx catalyst 6b, when the storage capacity of the NOx catalyst 6b approaches the limit, it is necessary to restore the storage capacity of the NOx catalyst 6b by supplying a reducing agent to the NOx catalyst 6b. Although gasoline can be used as the reducing agent, in this drive system, hydrogen excellent as a reducing agent is used as a fuel for the engine 2. If this hydrogen can be supplied to the NOx catalyst 6b as a reducing agent, the storage capacity of the NOx catalyst 6b can be efficiently recovered.

  In the present embodiment, hydrogen is supplied to the NOx catalyst 6b by cooperative control of the engine 2 and the motor 10 by the ECU 40. The routine shown in the flowchart of FIG. 2 is a routine for cooperative control of the engine 2 and the motor 10 that is executed to supply hydrogen to the NOx catalyst 6b. The ECU 40 periodically executes the routine shown in FIG. 2 for each constant crank angle.

  In the first step 100 of the routine shown in FIG. 2, it is determined whether or not a reduction process of the NOx catalyst 6b is necessary. The amount of NOx occluded in the NOx catalyst 6b can be estimated based on the operation time of the engine 2, the travel distance, and the like. In this step, the estimated NOx occlusion amount is compared with a predetermined reference value, and if the estimated occlusion amount exceeds the reference value, it is determined that the NOx catalyst 6b needs to be reduced. As a result of the determination, when the reduction process is not required, the normal operation according to the traveling state of the vehicle is continued (step 108).

  On the other hand, when it is determined that the reduction process of the NOx catalyst 6b is necessary, a series of processes of steps 102, 104, and 106 are executed. First, in step 102, a process for stopping the combustion of the engine 2 is executed. Specifically, fuel supply from the injectors 42 and 44 is stopped, and ignition by a spark plug (not shown) is stopped. The throttle (not shown) is also closed. At the same time, the electric power charged in the battery 28 is supplied from the inverter 24 to the motor 10 and traveling by the driving force of the motor 10 is started. At that time, the electric power supplied to the motor 10 is adjusted by the inverter 24 so that the driving force transmitted to the driving wheels 20 does not fluctuate before and after the engine 2 is stopped.

  In the next step 104, it is determined whether or not the combustion of the engine 2 has actually stopped. This is because there is a time lag from when the ECU 40 outputs a stop command to the injectors 42 and 44 and the spark plug until the combustion of the engine 2 actually stops. Whether combustion of the engine 2 has stopped can be determined by a change in the engine speed. In this step, the engine speed reduction speed is compared with a predetermined reference value. If the engine speed reduction speed exceeds the reference value, it is determined that the combustion of the engine 2 has stopped. Until the combustion of the engine 2 stops as a result of the determination, the processing of the next step 106 is skipped.

  When the combustion of the engine 2 has stopped, the process of step 106 is executed. In step 106, the power split mechanism 14 is operated, and a part of the driving force of the motor 10 is input to the engine 2 via the power split mechanism 14. Thus, the engine 2 is forcibly rotated by the driving force of the motor 10 and operates as a pump that sucks air from the intake manifold 2a and discharges it to the exhaust manifold 2b.

  In step 106, simultaneously with the forced rotation of the engine 2 by the motor 10, an injection command is supplied from the ECU 40 to the hydrogen injector 44, and a predetermined amount of hydrogen is injected from the hydrogen injector 44. In this case, the hydrogen injector 44 of each cylinder may be operated, or only the hydrogen injector 44 of a specific cylinder may be operated. Alternatively, the number of hydrogen injectors 44 to be operated may be determined according to the supply amount of hydrogen. The hydrogen injected from the hydrogen injector 44 to the intake manifold 2a is sucked into the combustion chamber by the pump action of the engine 2 and is directly discharged to the exhaust manifold 2b. Since the throttle is closed when the combustion of the engine 2 is stopped, the dilution with hydrogen air is small. Therefore, a gas with a very high hydrogen concentration flows into the catalyst device 6, and the ambient atmosphere of the NOx catalyst 6b is a rich reducing atmosphere. The NOx stored in the NOx catalyst 6b is reduced by hydrogen and released into the atmosphere as harmless nitrogen.

  When a predetermined amount of hydrogen is supplied to the NOx catalyst 6b and the reduction process of the NOx catalyst 6b is completed, the determination result in the next step 100 is negative (No). In that case, the process proceeds to step 108 and normal operation is resumed. In step 108, fuel supply from the injectors 42 and 44 and ignition by the spark plug are resumed, and the engine 2 is restarted. Then, traveling by the driving force of the engine 2 is resumed. At that time, the electric power supplied to the motor 10 is adjusted by the inverter 24 so that the driving force transmitted to the driving wheel 20 does not fluctuate before and after the restart of the engine 2.

  According to the routine described above, the hydrogen injected from the hydrogen injector 44 can be sent to the exhaust pipe 4 without burning by the pump action of the engine 2 when the engine 2 is forcibly rotated by the motor 10. Therefore, it is not necessary to provide a dedicated device for supplying hydrogen to the NOx catalyst 6b. In addition, according to the above routine, since the motor 10 travels while the combustion of the engine 2 is stopped, the combustion of the engine 2 can be stopped at any time. That is, when it is necessary to reduce the NOx catalyst 6b, hydrogen can be supplied to the NOx catalyst 6b at any time.

  In the above-described embodiment, the “control means” of the first invention is realized by the ECU 40 executing the routine.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG.
The exhaust emission control device for a hybrid vehicle of the present embodiment can be realized by causing the ECU 40 to execute a routine shown in FIG. 3 instead of the routine shown in FIG. 2 in the configuration shown in FIG. The ECU 40 periodically executes the routine shown in FIG. 3 at every constant crank angle. In FIG. 3, the same step numbers are assigned to the processes having the same contents as the routine shown in FIG.

  The routine shown in FIG. 3 is common to the routine shown in FIG. 2 from step 100 to step 104, and the processing after the combustion stop of the engine 2 is confirmed in the determination of step 104 is different. . In this routine, after the combustion of the engine 2 is stopped, it is further determined whether or not the rotation of the engine 2 is stopped (step 110). The engine 2 rotates for a while due to inertia even after the combustion stops, and then stops. At the time of determination in step 110, if the engine 2 continues to rotate, the process of step 112 is executed, and if the rotation of the engine 2 has already stopped, as in the routine shown in FIG. The process is executed.

  When the process of step 112 is selected, that is, when the engine 2 continues to rotate, the rotation angle of the crankshaft until the engine 2 stops from the inertia energy and stroke work of the engine 2 is calculated. The cylinder (final stop cylinder) that is finally stopped after the exhaust stroke is predicted from the rotation angle until the engine is stopped and the current rotation position of the crankshaft. When the final stop cylinder is in the final intake stroke, an injection command is supplied from the ECU 40 only to the hydrogen injector 44 of the final stop cylinder, and a predetermined amount of hydrogen is injected from the hydrogen injector 44 of the final stop cylinder. Hydrogen injected from the hydrogen injector 44 in the final intake stroke is sucked into the combustion chamber of the final stop cylinder by the pump action of the engine 2, and is discharged to the exhaust manifold 2b in the final exhaust stroke without burning. Then, the exhaust gas is supplied to the NOx catalyst 6 b in the catalyst device 6 through the exhaust pipe 4.

  On the other hand, when the process of step 106 is selected, that is, when the rotation of the engine 2 has already stopped, a part of the driving force of the motor 10 is input to the engine 2 via the power split mechanism 14, The engine 2 is forcibly rotated by the driving force of the motor 10. At the same time, an injection command is supplied from the ECU 40 to the hydrogen injectors 44 of all cylinders or specific cylinders, and a predetermined amount of hydrogen is injected from the hydrogen injector 44. Hydrogen injected from the hydrogen injector 44 is discharged as it is to the exhaust manifold 2 b by the pump action of the engine 2, and is supplied to the NOx catalyst 6 b in the catalyst device 6 through the exhaust pipe 4.

  After the reduction process of the NOx catalyst 6b is performed in step 112 or step 106, the determination result in step 100 is negative (No). In that case, the process proceeds to step 108 and normal operation is resumed. Specifically, the engine 2 is restarted, and traveling by the driving force of the engine 2 is resumed.

  According to the routine described above, after the combustion of the engine 2 is stopped, the hydrogen injected from the hydrogen injector 44 is sent to the exhaust pipe 4 without burning using the pump action when the engine 2 is rotating due to inertia. be able to. Therefore, it is not necessary to provide a dedicated device for supplying hydrogen to the NOx catalyst 6b. In addition, since hydrogen is supplied to the final stop cylinder that finally stops through the exhaust stroke, the hydrogen discharged to the exhaust manifold 2b is not diluted with air from other cylinders. That is, according to the above routine, it is possible to suppress the dilution of hydrogen with air, and it is possible to create a rich reducing atmosphere with a minimum amount of hydrogen.

  Further, according to the above routine, when the engine 2 has already stopped, the engine 2 can be forcibly rotated by the motor 10, so that the pumping action of the engine 2 when rotating due to inertia is achieved. Even if it cannot be used, hydrogen can be reliably supplied to the NOx catalyst 6b.

  In the above embodiment, the “control means” according to the fourth aspect of the present invention is realized by the ECU 40 executing the routine shown in FIG.

Embodiment 3 FIG.
Next, Embodiment 3 of the present invention will be described with reference to FIG.
The exhaust purification device for a hybrid vehicle of the present embodiment can be realized by causing the ECU 40 to execute the routine shown in FIG. 4 in the configuration shown in FIG.

  During the operation of the engine 2, the temperature of each of the catalysts 6 a and 6 b in the catalyst device 6 is high by being exposed to high-temperature exhaust gas. However, when the engine 2 is stopped as during travel by the motor 10, the temperatures of the respective catalysts 6a and 6b are lowered by heat radiation. The temperature of each catalyst 6a, 6b has an appropriate temperature at which the purification performance is maximized. If the catalyst temperature is too lower than the appropriate temperature, sufficient purification performance cannot be obtained. For this reason, when the catalyst temperature is low when the engine 2 is started, it is necessary to warm up the catalysts 6a and 6b so that the catalyst temperature rises to an appropriate temperature. In the configuration shown in FIG. 1, if at least the three-way catalyst 6a can be warmed up, the exhaust emission can be prevented from deteriorating by operating the engine 2 under the stoichiometric air-fuel ratio.

  One method for warming up the catalyst is a method in which fuel is reacted with oxygen on the catalyst, and the catalyst is heated by reaction heat. Gasoline can also be used as the warm-up fuel. However, in the drive system of this embodiment, hydrogen having excellent combustibility is used as the fuel for the engine 2. If it can supply to the original catalyst 6a, the three-way catalyst 6a can be warmed up efficiently.

  In the present embodiment, hydrogen is supplied to the three-way catalyst 6a by cooperative control of the engine 2 and the motor 10 by the ECU 40. The routine shown in the flowchart of FIG. 4 is a routine for cooperative control of the engine 2 and the motor 10 that is executed to supply hydrogen to the three-way catalyst 6a. The ECU 40 periodically executes the routine shown in FIG. 4 for each constant crank angle.

  In the first step 200 of the routine shown in FIG. 4, it is determined whether the engine 2 needs to be started. The engine 2 is started when traveling from the motor 10 is switched to traveling by the engine 2 or when the generator 12 is driven by the engine 2. As a result of the determination, when the engine 2 is not required to be started, this routine ends. The routine is also terminated when the engine 2 has been started by the subsequent processing.

  On the other hand, if it is determined that the engine 2 needs to be started, it is next determined whether or not the temperature of the three-way catalyst 6a is lower than a predetermined reference value (step 202). The reference value is set to the lower limit value of the appropriate temperature. As a result of the determination in step 202, when the catalyst temperature is lower than the reference value, the process of step 204 is executed. When the catalyst temperature is equal to or higher than the reference value, the process of step 206 is executed.

  When the process of step 204 is selected, that is, when the catalyst temperature is lower than the reference value, first, the power split mechanism 14 is operated, and part or all of the driving force of the motor 10 causes the power split mechanism 14 to be operated. Through the engine 2. Thus, the engine 2 is forcibly rotated by the driving force of the motor 10 and operates as a pump that sucks air from the intake manifold 2a and discharges it to the exhaust manifold 2b.

  In step 204, simultaneously with the forced rotation of the engine 2 by the motor 10, an injection command is supplied from the ECU 40 to the hydrogen injector 44, and a predetermined amount of hydrogen is injected from the hydrogen injector 44. At the same time, a throttle provided in an intake pipe (not shown) is opened, and an amount of air corresponding to the hydrogen injection amount is supplied to the intake manifold 2a. The amount of air can be controlled by the throttle opening. The ECU 40 controls the throttle so that the air-fuel ratio of hydrogen and air becomes a predetermined air-fuel ratio suitable for the combustion reaction on the catalyst. Hydrogen injected from the hydrogen injector 44 to the intake manifold 2a is sucked into the combustion chamber together with air by the pump action of the engine 2, and is discharged into the exhaust manifold 2b as a mixture of hydrogen and air. This air-fuel mixture is supplied to the three-way catalyst 6a in the catalyst device 6 through the exhaust pipe 4, and hydrogen and oxygen cause a combustion reaction on the three-way catalyst 6a, whereby the three-way catalyst 6a is heated and the three-way catalyst. The temperature of the catalyst 6a increases.

  When the temperature of the three-way catalyst 6a is increased by the process of step 204 and eventually becomes equal to or higher than the reference value, the process of step 204 is switched to the process of step 206. In step 206, first, the injection of hydrogen from the hydrogen injector 44 is stopped. Then, fuel supply from the gasoline injector 42 and ignition by the spark plug are started, and the engine 2 is started. After the engine 2 is started, the high-temperature exhaust gas discharged from the engine 2 is supplied to the three-way catalyst 6a, so that the temperature of the three-way catalyst 6a is maintained at an appropriate temperature.

  According to the routine described above, the hydrogen injected from the hydrogen injector 44 can be sent to the exhaust pipe 4 without burning by the pump action of the engine 2 when the engine 2 is forcibly rotated by the motor 10. Thereby, prior to starting the engine 2, hydrogen and oxygen are reacted on the three-way catalyst 6a, and the three-way catalyst 6a can be warmed up by the reaction heat at that time. In addition, the combustion reaction of hydrogen and oxygen on the three-way catalyst 6a can be promoted by adjusting the air-fuel ratio, and the three-way catalyst 6a can be warmed up efficiently.

  In the above-described embodiment, the “control means” of the first invention is realized by the ECU 40 executing the routine. Further, the function of the “control means” according to the second and third inventions is realized.

  While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the following modifications may be made.

  In the configuration of FIG. 1, the hydrogen injector 44 is arranged in the intake manifold 2a, but the arrangement is not limited to this. That is, the hydrogen injector 44 may be incorporated in the cylinder head so that hydrogen can be injected directly into the combustion chamber. The same applies to the gasoline injector 42, and the gasoline injector 42 may be incorporated in the cylinder head so that gasoline can be injected directly into the combustion chamber. In the second embodiment, hydrogen is injected in the last intake stroke of the final stop cylinder. However, if hydrogen can be injected directly into the combustion chamber, an arbitrary period between the last intake stroke and the last exhaust stroke can be set. Hydrogen can be injected at this timing.

  In the configuration of FIG. 1, hydrogen stored in the hydrogen tank 34 is supplied to the hydrogen injector 44, but hydrogen reformed from a hydrocarbon fuel (for example, gasoline) by the fuel reformer is used as the hydrogen injector. 44 may be supplied. There is no limitation on the method of reforming the hydrocarbon-based fuel by the fuel reformer, and a partial oxidation reaction may be used or a steam reforming reaction may be used. Alternatively, hydrogen obtained by dehydrogenating the hydrogenated fuel may be supplied to the hydrogen injector 44.

  In the configuration of FIG. 1, the hybrid vehicle is configured to be able to travel by both the engine 2 and the motor 10. However, in applying the present invention, the hybrid vehicle only needs to be capable of traveling by at least the motor 10. That is, the engine 2 may be dedicated for power generation.

  Further, in the above embodiment, hydrogen is used as the reducing agent for reducing the NOx catalyst 6b, but a reducing agent other than hydrogen may be used. For example, a hydrocarbon fuel may be used as the reducing agent.

It is a figure which shows the structure of the drive system of the hybrid vehicle to which the exhaust gas purification apparatus of this invention was applied. It is a flowchart shown about the routine of the engine and motor cooperation control performed in Embodiment 1 of this invention. It is a flowchart shown about the routine of the cooperative control of the engine and motor performed in Embodiment 2 of this invention. It is a flowchart shown about the routine of the cooperative control of the engine and motor performed in Embodiment 3 of this invention.

Explanation of symbols

2 Engine 2a Intake manifold 2b Exhaust manifold 4 Exhaust pipe 6 Catalytic device 6a Three-way catalyst 6b NOx catalyst 8 Muffler 10 Motor 12 Generator 14 Power split mechanism 16 Reducer 18 Drive shaft 20 Drive wheel 24 Inverter 26 Converter 28 Battery 32 Gasoline tank 34 Hydrogen tank 40 ECU
42 Gasoline injector 44 Hydrogen injector

Claims (4)

An exhaust purification device for a hybrid vehicle having an internal combustion engine and a motor and capable of driving the vehicle by at least the motor,
An exhaust purification catalyst provided in an exhaust passage of the internal combustion engine;
Reducing agent supply means for supplying a reducing agent into the intake passage or combustion chamber of the internal combustion engine;
When the supply timing of the reducing agent to the exhaust purification catalyst is determined and it is determined from the determination result that it is time to supply the reducing agent, the motor performs the above-described operation in a state where combustion of the internal combustion engine is stopped. Control means for forcibly rotating the internal combustion engine and operating the reducing agent supply means to supply the reducing agent;
An exhaust emission control device for a hybrid vehicle comprising: The reducing agent supply means is configured to supply hydrogen as a reducing agent,
2. The exhaust gas purification apparatus for a hybrid vehicle according to claim 1, wherein the control means sets the start timing of the internal combustion engine as a supply timing of hydrogen to the exhaust gas purification catalyst.   The hybrid vehicle according to claim 2, wherein the control means controls the opening of the throttle so that the air-fuel ratio of the air-fuel mixture containing hydrogen supplied to the exhaust purification catalyst becomes a predetermined air-fuel ratio. Exhaust purification device. An exhaust purification device for a hybrid vehicle having an internal combustion engine and a motor and capable of driving the vehicle by at least the motor,
An exhaust purification catalyst provided in an exhaust passage of the internal combustion engine;
Reducing agent supply means for supplying a reducing agent into the intake passage or combustion chamber of the internal combustion engine;
The supply timing of the reducing agent to the exhaust purification catalyst is determined, and when it is determined that it is time to supply the reducing agent, the combustion of the internal combustion engine is stopped and the rotation of the internal combustion engine is stopped. Prior to the operation, the cylinder that stops last through the exhaust stroke is predicted, and the reducing agent is supplied from the reducing agent supply means to the cylinder so that the reducing agent is discharged from the cylinder in the final exhaust stroke of the cylinder. An exhaust emission control device for a hybrid vehicle.

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