JP2007269227A - Hybrid car - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve low emission even while warming up an exhaust gas purifying catalyst concerning a hybrid car. <P>SOLUTION: This hybrid car 1 is provided with an internal combustion engine 2 which can operate by using both gasoline and hydrogen as fuel and a motor 4. When it is necessary to increase the temperature of the exhaust gas purifying catalyst 15, only hydrogen is used for the fuel of the internal combustion engine 2, and a catalyst warming-up hydrogen lean operation operating by an excess air factor λ>1 is performed, and an ignition period is lagged to increase an exhaust gas temperature, and the warming-up of the exhaust gas purifying catalyst 15 is promoted. In operating the catalyst warming-up hydrogen lean operation, a power stored in a battery 20 is supplied to the motor 4 to operate the motor 4 for compensating the insufficiency of the output of the internal combustion engine 2 with respect to a requested traveling output so that the traveling of the vehicle 1 can be assisted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hybrid vehicle including an internal combustion engine that can be operated using hydrogen as a fuel, and another power source.

  The exhaust purification catalyst of the internal combustion engine cannot obtain a high purification rate unless the temperature is higher than the activation temperature (for example, about 300 ° C.). For this reason, in order to further reduce the emission, it is important to warm up the catalyst as early as possible when the catalyst is not warmed, such as immediately after the start of the internal combustion engine. In order to warm up the catalyst quickly, it is effective to raise the exhaust temperature by retarding the ignition timing. In order to reduce emissions, it is also important to reduce the HC, CO, and NOx emissions from the internal combustion engine during catalyst warm-up as much as possible.

  Japanese Patent Application Laid-Open No. 2005-48631 discloses an internal combustion engine that is provided with a means for adding hydrogen in addition to the main fuel when the exhaust gas temperature rises in an internal combustion engine that retards the ignition timing at the time of starting the engine and raises the exhaust gas temperature. A catalyst temperature raising device is disclosed.

  Generally, the exhaust gas temperature can be increased as the ignition timing is retarded. Therefore, in order to warm up the catalyst earlier, it is desirable to retard the ignition timing significantly. However, if the ignition timing is significantly retarded, combustion deteriorates and the amount of HC emission increases, so there is a problem that the total amount of HC released into the atmosphere during catalyst warm-up increases.

  With respect to such a problem, according to the catalyst temperature raising device disclosed in the above publication, combustion can be improved by adding hydrogen having a combustion promoting effect as an auxiliary fuel. Even if the ignition retardation is performed properly, the amount of HC emission can be kept low.

JP 2005-48631 A

  In recent years, in order to preserve the global environment, there has been a demand for further reduction in internal combustion engine emissions. For this reason, it is desired to further reduce the emission amount of not only HC but also NOx and CO at the time of catalyst warm-up such as when the internal combustion engine is started.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a hybrid vehicle that can realize low emission even while the exhaust purification catalyst is warmed up.

In order to achieve the above object, a first invention is a hybrid vehicle including an internal combustion engine that can be operated using hydrogen as a fuel, and another power source,
Hydrogen supply means for supplying hydrogen to the internal combustion engine;
An exhaust purification catalyst disposed in an exhaust passage of the internal combustion engine;
Requested running output calculating means for calculating the requested running output;
A catalyst warm-up hydrogen lean operation means for performing a catalyst warm-up hydrogen lean operation for operating the internal combustion engine with an excess air ratio λ> 1 when the temperature of the exhaust purification catalyst needs to be raised; ,
Assist means for operating the other power source so as to compensate for a shortage of the output of the internal combustion engine with respect to the required travel output during the catalyst warm-up hydrogen lean operation;
It is characterized by providing.

The second invention is the first invention, wherein
The excess air ratio λ during the catalyst warm-up hydrogen lean operation is a value such that almost no NOx is discharged from the internal combustion engine.

The third invention is the first or second invention, wherein
The internal combustion engine can also be operated with liquid fuel,
Liquid fuel supply means for supplying liquid fuel to the internal combustion engine;
Fuel supply switching for operating the liquid fuel supply means and the hydrogen supply means to supply only hydrogen without supplying liquid fuel to the internal combustion engine when the temperature of the exhaust purification catalyst needs to be raised Means,
Is further provided.

According to a fourth invention, in any one of the first to third inventions,
It further comprises ignition retarding means for retarding the ignition timing of the internal combustion engine as compared with the normal time during the catalyst warm-up hydrogen lean operation.

According to a fifth invention, in any one of the first to third inventions,
An electric heater capable of heating the exhaust purification catalyst;
Catalyst warm-up auxiliary means for heating the exhaust purification catalyst by energizing the electric heater during the catalyst warm-up hydrogen lean operation;
Is further provided.

The sixth invention is the fifth invention, wherein
A generator capable of generating electric power by the power of the internal combustion engine;
The catalyst warm-up assisting unit supplies the electric power generated by the generator to the electric heater.

  According to the first invention, when the exhaust purification catalyst is warmed up, it is possible to perform a catalyst warm-up hydrogen lean operation in which only the hydrogen is used as fuel and the internal combustion engine is operated at an excess air ratio λ> 1. As a result, the HC and CO emissions from the internal combustion engine can be made zero, and the NOx emissions can be kept low. Therefore, even when the internal combustion engine is started, immediately after startup, or during light load operation, even when the temperature of the exhaust purification catalyst does not reach the activation temperature, emission released into the atmosphere can be kept low. . Further, according to the first aspect of the invention, during the catalyst warm-up hydrogen lean operation, it is possible to assist the traveling of the vehicle by operating the other power source so as to compensate for the insufficient output of the internal combustion engine with respect to the required traveling output. . For this reason, the low emission can be achieved without deteriorating drivability.

  According to the second aspect of the invention, not only HC and CO but also NOx can be hardly discharged from the internal combustion engine during the catalyst warm-up hydrogen lean operation. For this reason, the emission can be further reduced.

  According to the third aspect of the invention, since the internal combustion engine can be operated with liquid fuel, liquid fuel is mainly used in normal times, and only hydrogen is supplied to the internal combustion engine when the exhaust purification catalyst is warmed up. Can be switched. As a result, the consumption of hydrogen can be reduced, and the liquid fuel that can be easily mounted on the vehicle can be used as the main fuel. Therefore, the system can be simplified and the cruising distance can be extended.

  According to the fourth invention, the exhaust gas temperature can be raised by retarding the ignition timing of the internal combustion engine during the catalyst warm-up hydrogen lean operation. For this reason, the exhaust purification catalyst can be quickly warmed up.

  According to the fifth invention, the exhaust purification catalyst can be heated by the electric heater during the catalyst warm-up hydrogen lean operation. For this reason, the exhaust purification catalyst can be quickly warmed up.

  According to the sixth invention, when the exhaust gas purification catalyst is heated by the electric heater, the electric power generated by driving the generator by the power of the internal combustion engine can be supplied to the electric heater. For this reason, even if the required travel output is small, the load of the internal combustion engine can be increased to some extent, and the exhaust energy flowing into the exhaust purification catalyst can be increased. Therefore, even if the required travel output is small, the exhaust purification catalyst can be quickly warmed up in combination with the heating by the electric heater. That is, the exhaust purification catalyst can be quickly warmed up regardless of the traveling conditions such as when the vehicle is stopped or when traveling at a low speed.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a diagram for explaining a hybrid vehicle according to a first embodiment of the present invention. As shown in FIG. 1, a hybrid vehicle (hereinafter simply referred to as “vehicle”) 1 of this embodiment includes an internal combustion engine 2, a three-shaft power distribution and integration mechanism 3, a motor 4, and a generator 5. Have.

  The power distribution and integration mechanism 3 includes a planetary gear mechanism. The planetary carrier of the power distribution and integration mechanism 3 is connected to the crankshaft of the internal combustion engine 2. The ring gear of the power distribution and integration mechanism 3 is connected to the motor 4 and is also connected to the input side of the drive system 6. The sun gear of the power distribution and integration mechanism 3 is connected to the generator 5.

  The output side of the drive system 6 is connected to the front drive shaft 7 of the vehicle 1. The power transmitted by the drive system 6 drives the drive wheels 8 via the front drive shaft 7. The vehicle 1 of the present embodiment is a front-wheel drive vehicle having front wheels as drive wheels 8, but the vehicle of the present invention may be a rear-wheel drive vehicle having rear wheels 9 as drive wheels, or an all-wheel drive vehicle. Good.

  The power distribution and integration mechanism 3 can bisect the power of the internal combustion engine 2 and transmit it to the generator 5 and the drive system 6 (drive wheels 8). Further, the power distribution and integration mechanism 3 can integrate the power of the internal combustion engine 2 and the power of the motor 4 and transmit them to the drive system 6 (drive wheels 8).

  The internal combustion engine 2 can be operated using both gasoline (liquid fuel) and hydrogen (hydrogen gas) as fuel. The internal combustion engine 2 includes a gasoline injector 10 that injects gasoline and a hydrogen injector 11 that injects hydrogen gas. Details of the internal combustion engine 2 will be described later.

  The vehicle 1 includes a gasoline tank 12 that stores gasoline to be supplied to the gasoline injector 10 and a hydrogen tank 13 that stores hydrogen gas to be supplied to the hydrogen injector 11.

  An exhaust purification catalyst 15 for purifying exhaust gas is disposed in the middle of the exhaust passage 14 of the internal combustion engine 2. The exhaust purification catalyst 15 is composed of, for example, a three-way catalyst, an occlusion reduction type NOx catalyst, a selective reduction type NOx catalyst, or the like. Moreover, what combined those functions may be used.

  A catalyst temperature sensor 16 for detecting the temperature of the exhaust purification catalyst 15 is attached to the exhaust purification catalyst 15. A muffler 17 is installed in the exhaust passage 14 downstream of the exhaust purification catalyst 15. In the present embodiment, the temperature of the exhaust purification catalyst 15 is directly detected by the catalyst temperature sensor 16. However, in the present invention, the temperature of the exhaust purification catalyst 15 is based on the operating state of the internal combustion engine 2 or the like. You may make it estimate by a well-known method.

  Each of the motor 4 and the generator 5 is configured as a known synchronous generator motor that can be driven as a generator and can be driven as a motor. In the vehicle 1, the electric power generated by the generator 5 can be charged to the battery 20 via the inverter 18 and the boost converter 19. In addition, the motor 4 can be driven by the electric energy stored in the battery 20 via the boost converter 19 and the inverter 18. Further, in the vehicle 1, the motor 4 can be driven by applying the electric power generated by the generator 5 to the motor 4 through the inverter 18. In the vehicle 1, other power storage means such as a capacitor may be used instead of the battery 20.

  In the vicinity of the internal combustion engine 2, an auxiliary machine 21 such as an electric air conditioner compressor is arranged. The auxiliary machine 21 is driven by electric power supplied from the battery 20 via the inverter 18. The vehicle 1 is also provided with a vehicle speed sensor 22 that detects the vehicle speed and an accelerator opening sensor 23 that detects the amount of depression of the accelerator pedal.

  Such a vehicle 1 is provided with an ECU (Electronic Control Unit) 30 as a control device for controlling the hybrid system described above. The ECU 30 is connected to the various actuators, sensors, power conversion devices, batteries, and the like described above.

  FIG. 2 is a diagram for further explaining the internal combustion engine 2 mounted on the vehicle 1. FIG. 2 shows only one of the plurality of cylinders included in the internal combustion engine 2. The internal combustion engine 2 of the present embodiment is a spark ignition type four-cycle engine. Each cylinder of the internal combustion engine 2 is provided with a piston 31, an intake valve 32, an exhaust valve 33, and a spark plug 34.

  The above-described gasoline injector 10 and hydrogen injector 11 are arranged in the intake port 35 of each cylinder, respectively, so that gasoline and hydrogen gas can be injected into the intake port 35. In the present invention, the gasoline injector 10 may be installed so that gasoline can be directly injected into the cylinder. The hydrogen injector 11 may also be installed so that hydrogen gas can be directly injected into the cylinder.

  The gasoline in the gasoline tank 12 is pressurized by the fuel pump 36, regulated by the regulator valve 37, and then supplied to the gasoline injector 10. The compressed hydrogen gas in the hydrogen tank 13 is regulated by a regulator valve 38 and then supplied to the hydrogen injector 11.

  In the present embodiment, the case where gasoline is used as the liquid fuel of the internal combustion engine 2 will be described. However, the liquid fuel of the internal combustion engine 2 in the present invention is not limited to gasoline, but includes methanol, ethanol, organic hydride, and the like. Other hydrocarbon fuels may be used.

  In the present embodiment, the hydrogen gas to be supplied to the injector 11 is stored in the hydrogen tank 13 as a gas, but the method for storing hydrogen in the vehicle 1 is not limited to this. For example, it may be stored in a tank as liquid hydrogen or stored in a state of being stored in a hydrogen storage alloy. Further, hydrogen may be generated on the vehicle 1 by dehydrogenating an organic hydride fuel such as cyclohexane or decalin using a catalyst or by electrolyzing water.

  Further, the internal combustion engine 2 of the present embodiment has an intake variable valve operating mechanism 39 that makes the valve opening characteristics (opening / closing timing, operating angle, etc.) of the intake valve 32 variable, and an exhaust that makes the valve opening characteristics of the exhaust valve 33 variable. And a variable valve mechanism 40.

  Further, the internal combustion engine 2 of the present embodiment includes a turbocharger 41. An exhaust passage 14 of the internal combustion engine 2 is connected to the exhaust turbine of the turbocharger 41, and the turbocharger 14 is operated by the energy of the exhaust gas.

  An intake passage 42 of the internal combustion engine 2 is connected to the intake compressor of the turbocharger 41. The intake air that has been compressed by the intake compressor of the turbocharger 41 and has risen in temperature is cooled by the intercooler 43 and then distributed to the intake port 35 of each cylinder by an intake manifold (not shown).

  A throttle valve 44 for adjusting the intake air amount is installed in the intake passage 42 downstream of the intercooler 43. The throttle valve 44 is an electronically controlled throttle that is driven by a throttle motor (not shown) based on the control of the ECU 30. An air flow meter 45 that detects the intake air amount is installed in the intake passage 42 upstream of the turbocharger 41. In the present invention, the internal combustion engine 2 may be a naturally aspirated engine that does not include a supercharger.

  The above-mentioned various actuators and sensors provided in the internal combustion engine 2 are connected to the ECU 30, and the operating conditions of the internal combustion engine 2 are controlled by the ECU 30.

  Such an internal combustion engine 2 is normally operated by using gasoline supplied from the gasoline injector 10 as a main fuel and, if necessary, using hydrogen supplied from the hydrogen injector 11 as an auxiliary fuel.

  In addition to the theoretical air-fuel ratio operation in which the excess air ratio (hereinafter may be simply referred to as “λ”) is 1 and the rich air-fuel ratio operation in which λ <1 is set, the internal combustion engine 2 satisfies λ> 1. Lean air-fuel ratio operation is possible. Generally, the leaner the air-fuel ratio, the more easily the combustion becomes unstable. On the other hand, in the internal combustion engine 2, combustion can be promoted / improved by adding hydrogen having a high combustion speed as an auxiliary fuel. For this reason, even if it is a lean air fuel ratio, it can be burned stably. Therefore, in the internal combustion engine 2, by adding hydrogen as an auxiliary fuel, the combustible range can be expanded to the lean side, and operation at a leaner air-fuel ratio can be performed than in the case of gasoline alone.

[Features of Embodiment 1]
The internal combustion engine 2 of the present embodiment can be operated using only hydrogen supplied from the hydrogen injector 11 as fuel, without using gasoline, in addition to operation using gasoline as the main fuel.

  FIG. 3 is a graph showing the relationship between the NOx emission amount from the internal combustion engine 2 and the excess air ratio λ. The solid line in the figure is a graph when the internal combustion engine 2 is operated using only hydrogen as a fuel, and the broken line is a graph when operating only gasoline as a fuel. As shown in the figure, when the internal combustion engine 2 is operated using only hydrogen as a fuel, the amount of NOx emission decreases as λ increases. Specifically, the amount of NOx emission becomes extremely small when λ = 2, and the amount of NOx emission can be made substantially zero when λ ≧ 2.4.

  FIG. 4 is a diagram showing the relationship between the magnitude of torque fluctuation occurring in the internal combustion engine 2 and the excess air ratio λ. The solid line in the figure is a graph when the internal combustion engine 2 is operated using only hydrogen as a fuel, and the broken line is a graph when operating only gasoline as a fuel. As shown in the figure, when only gasoline is used as fuel, generally, when λ ≧ 2, the torque fluctuation due to combustion fluctuation exceeds the allowable value. It is difficult. On the other hand, hydrogen has a wide flammable range, and even when diluted, combustion fluctuations are small, so that torque fluctuations can be kept small. That is, when only hydrogen is used as the fuel, operation in the range of λ ≧ 2 can be sufficiently realized, and operation up to about λ = 4 is possible.

  Thus, if only the hydrogen is used as fuel and the internal combustion engine 2 is operated in a range where the excess air ratio λ is large to some extent, NOx can be hardly discharged from the internal combustion engine 2. Therefore, in the present embodiment, when the temperature of the exhaust purification catalyst 15 is lower than the activation temperature, such as immediately after the start of the internal combustion engine 2 or during light load running, only hydrogen is used as fuel and almost no NOx is present. It is assumed that the exhaust purification catalyst 15 is warmed up by operating the internal combustion engine 2 at an excess air ratio λ that is not discharged. Such operation is hereinafter referred to as “catalyst warm-up hydrogen lean operation”.

  During the catalyst warm-up hydrogen lean operation, only hydrogen is used as the fuel, so that no carbon atoms are contained in the fuel. For this reason, the discharge amount of HC and CO can be made zero. That is, in the vehicle 1, the exhaust purification catalyst 15 can be warmed up to the activation temperature or more without releasing any of NOx, HC, and CO into the atmosphere. For this reason, according to the vehicle 1, NOx, HC, and CO emissions during start-up and immediately after the start-up of the internal combustion engine 2 and during light-load travel can be greatly reduced, and low emissions can be achieved.

  In this embodiment, the ignition timing is retarded from that during normal operation during the catalyst warm-up hydrogen lean operation. Thereby, exhaust temperature can be raised and warming-up of the exhaust purification catalyst 15 can be accelerated | stimulated.

  During the catalyst warm-up hydrogen lean operation, the excess air ratio λ is increased as described above. Since the amount of air that can be taken into the cylinder is limited, in order to increase the excess air ratio λ, it is necessary to reduce the amount of fuel (the amount of hydrogen) supplied into the cylinder. For this reason, the output that can be generated during the catalyst warm-up hydrogen lean operation is smaller than that during the normal operation.

  Further, since the exhaust gas temperature can be increased as the ignition timing is retarded, it is desirable to increase the ignition retard amount as much as possible in order to promote warm-up of the exhaust purification catalyst 15. However, as the ignition retard amount is increased, the amount of work that the combustion gas in the cylinder does with respect to the piston 31 decreases, the engine output decreases, and the combustion also deteriorates.

  For this reason, during the catalyst warm-up hydrogen lean operation, the output that can be generated by the internal combustion engine 2 tends to be small, so that the output of the internal combustion engine 2 is insufficient with respect to the required travel output of the vehicle 1. easy. Therefore, in the present embodiment, when the internal combustion engine 2 is performing the catalyst warm-up hydrogen lean operation, the electrical energy stored in the battery 20 is output via the motor 4 to compensate for such shortage. did. As a result, the vehicle 1 can achieve low emission as described above without deteriorating drivability.

  Further, since the assist by the motor 4 can be expected during the catalyst warm-up hydrogen lean operation, the ignition timing can be greatly retarded without worrying about a decrease in the output of the internal combustion engine 2. For this reason, the exhaust temperature can be made higher, and the exhaust purification catalyst 15 can be quickly warmed up.

[Specific Processing in Embodiment 1]
FIG. 5 is a flowchart of a routine executed by the ECU 30 in the present embodiment in order to realize the above function. This routine is repeatedly executed every predetermined time.

  According to the routine shown in FIG. 5, first, the required travel output from the driver of the vehicle 1 is calculated based on the accelerator opening and the vehicle speed (step 100). Next, the output required for the internal combustion engine 2 is calculated based on the required travel output (step 102). In this step 102, it is also determined whether or not there is a request for charging the battery 20 based on the state of charge (SOC) of the battery 20. If there is a request for charging, the internal combustion engine including the output for driving the generator 5 is also included. The required output of 2 is calculated.

  Subsequently, the engine speed and load necessary for generating the required output calculated in step 102 are calculated. Then, based on the map stored in advance according to the engine speed and the load, the operating conditions such as the required supply heat amount (fuel injection amount) to the internal combustion engine 2, the excess air ratio λ, the hydrogen addition ratio, the ignition timing, and the like. It is determined (step 104).

  The operating condition of the internal combustion engine 2 determined in step 104 is an operating condition that is applied when the exhaust purification catalyst 15 is already warmed up, that is, when normal operation using gasoline is possible. Therefore, following the processing of step 104, it is determined whether or not the temperature of the exhaust purification catalyst 15 is equal to or lower than a first predetermined value in order to determine whether or not the exhaust purification catalyst 15 has been warmed up ( Step 106). The first predetermined value is set based on a catalyst activation temperature at which the exhaust purification catalyst 15 can exhibit sufficient purification performance, and is set to about 300 ° C., for example.

  If the temperature of the exhaust purification catalyst 15 is equal to or lower than the first predetermined value in step 106, the temperature of the exhaust purification catalyst 15 has not reached the catalyst activation temperature, and the exhaust purification catalyst 15 is warmed up (temperature rise). ) Is necessary. Therefore, in this case, the catalyst warm-up hydrogen lean operation is executed with a delay of the ignition timing (step 108). Specifically, the injection of gasoline from the gasoline injector 10 is stopped, only hydrogen is injected from the hydrogen injector 11, and the excess air ratio λ is such that almost no NOx is exhausted. The opening degree and the hydrogen injection amount from the hydrogen injector 11 are controlled. Further, the ignition timing is sufficiently retarded so as to obtain an exhaust temperature that can raise the temperature of the exhaust purification catalyst 15 quickly.

  Note that “the excess air ratio λ such that almost no NOx is exhausted” in step 108 is preferably λ ≧ 2 and more preferably in the case of the internal combustion engine 2 having the NOx emission characteristics as shown in FIG. It is about (lambda)> = 2.4. However, it may be λ <2. Further, since the NOx emission characteristic varies depending on the model of the internal combustion engine 2, the value of λ during the catalyst warm-up hydrogen lean operation is not limited to the above value.

  Subsequent to the process of step 108, an insufficient amount of output of the internal combustion engine 2 with respect to the required travel output is calculated (step 110). Specifically, first, based on values such as the excess air ratio λ, hydrogen injection amount, ignition timing, and the like in the currently performed catalyst warm-up hydrogen lean operation, the current output of the internal combustion engine 2 according to a prestored map Is calculated. Then, a value obtained by subtracting the current engine output from the required travel output calculated in step 100 is calculated as an output shortage amount.

  If the output of the internal combustion engine 2 is insufficient based on the calculation result in step 110, travel output assist control by the motor 4 is executed (step 112). Specifically, electric energy corresponding to the output shortage calculated in step 110 is supplied from the battery 20 to the motor 4 via the boost converter 19 and the inverter 18, and the motor 4 is driven to Assist driving.

  When the travel output assist control is executed, or when it is determined in step 106 that the temperature of the exhaust purification catalyst 15 exceeds the first predetermined value, the temperature of the exhaust purification catalyst 15 is next increased. It is determined whether or not the second predetermined value is exceeded (step 114). The second predetermined value is set to a temperature higher than the first predetermined value, and is about 350 ° C., for example.

  If it is determined in step 114 that the temperature of the exhaust purification catalyst 15 is equal to or higher than the second predetermined value, it can be determined that the temperature of the exhaust purification catalyst 15 is sufficiently high and the warm-up has been completed. Therefore, in this case, the internal combustion engine 2 is shifted to the normal operation and is operated under the operation condition determined in the above step 104 (step 116).

  On the other hand, if it is determined in step 114 that the temperature of the exhaust purification catalyst 15 is lower than the second predetermined value, the exhaust purification catalyst 15 is above the activation temperature, but the warm-up is insufficient. Yes, it can be judged that it is better to continue warming up for a while. Therefore, in this case, the processing after step 108 is performed again, and the catalyst warm-up hydrogen lean operation of the internal combustion engine 2 and the travel output assist control by the motor 4 are continued.

  After warming up of the exhaust purification catalyst 15 is completed and the internal combustion engine 2 shifts to normal operation, normal travel output assist control is executed (step 118). As the travel output assist control here, the internal combustion engine 2 is stopped, for example, in a control where the motor 4 assists when the vehicle 1 is accelerated, or in an operation region where the engine efficiency is poor such as low speed travel or downhill. Thus, control such as traveling by the motor 4 is performed.

  According to the routine processing shown in FIG. 5 described above, when the exhaust purification catalyst 15 needs to be warmed up, the internal combustion engine 2 is operated at an excess air ratio λ that uses only hydrogen as fuel and hardly emits NOx. Catalyst warm-up hydrogen lean operation can be performed. For this reason, it is possible to hardly release NOx, HC, and CO into the atmosphere until the exhaust purification catalyst 15 is warmed up. Therefore, NOx, HC, and CO emissions during start-up and immediately after start-up of the internal combustion engine 2 and during light-load travel can be greatly reduced, and low emissions can be achieved.

  Further, according to the routine processing shown in FIG. 5, the catalyst warm-up hydrogen lean operation is performed with the retard of the ignition timing. For this reason, the exhaust temperature can be increased, and the exhaust purification catalyst 15 can be warmed up quickly. Further, during the catalyst warm-up hydrogen lean operation, the travel output assist control by the motor 4 is performed, so that the required travel output can be satisfied even if the output of the internal combustion engine 2 is reduced. For this reason, the exhaust purification catalyst 15 can be warmed up without deteriorating drivability.

  Further, during the catalyst warm-up hydrogen lean operation, the excess air ratio λ is increased, so that the internal combustion engine 2 can be operated in a region with high thermal efficiency. For this reason, fuel consumption (hydrogen consumption) during warming-up of the exhaust purification catalyst 15 can be saved.

  In the first embodiment described above, the spark ignition operation is performed even when the internal combustion engine 2 is operated with liquid fuel. However, in the present invention, the internal combustion engine 2 uses light oil or the like as the liquid fuel. In the case of operating with liquid fuel, the compression ignition operation may be performed.

  Further, in the first embodiment described above, the internal combustion engine 2 can be operated with both hydrogen and liquid fuel, and it has been described that only the hydrogen purification catalyst 15 is operated using only hydrogen as a fuel when the exhaust purification catalyst 15 is warmed up. The hybrid vehicle of the present invention may be one in which the internal combustion engine 2 is always operated only with hydrogen.

  In the first embodiment described above, a hybrid vehicle including an electric motor (motor 4) as a power source other than the internal combustion engine 2 has been described as an example. However, the hybrid vehicle in the present invention is limited to an electric hybrid. Instead, for example, a mechanical hybrid such as a pressure accumulating hybrid may be used.

  Further, in the first embodiment described above, the travel output assist control by the motor 4 is performed even during the normal operation. However, in the present invention, the travel output assist control is performed only during the warm-up of the exhaust purification catalyst 15, and the normal operation is performed. Sometimes, the vehicle may run only with the output of the internal combustion engine 2.

  In the first embodiment described above, the motor 4 is the “other power source” in the first invention, and the hydrogen injector 11 and the hydrogen tank 13 are the “hydrogen supply means” in the first invention. It corresponds. Further, when the ECU 30 executes the process of step 100, the “required travel output calculating means” in the first aspect of the invention executes the process of step 108, whereby the “catalyst warm-up” in the first aspect of the invention is performed. The “assisting means” in the first aspect of the present invention is realized by the “hydrogen lean operation means” executing the processing of step 112 described above.

  In the first embodiment described above, the gasoline injector 10 and the gasoline tank 12 correspond to the “liquid fuel supply means” in the third aspect of the present invention. Further, when the ECU 30 stops supplying gasoline and supplies only hydrogen during the catalyst warm-up hydrogen lean operation, the “fuel supply switching means” in the third aspect of the invention executes the processing of step 108 described above. The “ignition retarding means” in the fourth aspect of the invention is realized.

Embodiment 2. FIG.
Next, the second embodiment of the present invention will be described with reference to FIG. 6 and FIG. 7. The description will focus on the differences from the first embodiment described above, and the same matters will be described. Omitted or simplified.

[Description of system configuration]
FIG. 6 is a diagram for explaining the hybrid vehicle according to the second embodiment of the present invention. In FIG. 6, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted or simplified. As shown in FIG. 6, the vehicle 1 of the second embodiment is provided with an electric heater 48 that can heat the exhaust purification catalyst 15. Electricity generated by the generator 5 can be supplied to the electric heater 48 via the inverter 18.

[Features of Embodiment 2]
In the present embodiment, when the catalyst warm-up hydrogen lean operation is performed when the exhaust purification catalyst 15 is warmed up, a part of the power of the internal combustion engine 2 is distributed to the generator 5 to generate power, and the generated electricity is supplied to the electric heater 48. It was decided to energize. Thereby, since the exhaust purification catalyst 15 can be heated by both the exhaust gas and the electric heater 48, the exhaust purification catalyst 15 can be warmed up more quickly.

[Specific Processing in Second Embodiment]
FIG. 7 is a flowchart of a routine executed by the ECU 30 in the present embodiment in order to realize the above function. In FIG. 7, the same steps as those shown in FIG. 5 are denoted by the same reference numerals, and the description thereof is omitted or simplified. According to the routine shown in FIG. 7, steps 100 to 106 are performed in the same manner as in the first embodiment.

  When it is determined in step 106 that the temperature of the exhaust purification catalyst 15 is equal to or lower than the first predetermined value, the catalyst has an excess air ratio λ such that only hydrogen is used as fuel and almost no NOx is discharged. A warm-up hydrogen lean operation is performed (step 120). In the catalyst warm-up hydrogen lean operation of the present embodiment, the ignition delay is not performed, but the ignition retard may be performed as in the first embodiment.

  When the catalyst warm-up hydrogen lean operation is started, next, the generator 5 is driven by a part of the power of the internal combustion engine 1 to generate power, and the generated electricity is energized to the electric heater 48 via the inverter 18. (Step 122). Thereby, the exhaust purification catalyst 15 is heated by the electric heater 48, and warming-up of the exhaust purification catalyst 15 can be promoted.

  Subsequent to the process of step 122, an insufficient amount of output of the internal combustion engine 2 is calculated (step 124). Here, first, the current engine output and the power consumed by the generator 5 are calculated. Then, a value obtained by subtracting the current engine output and the power consumed by the generator 5 from the required travel output calculated in step 100 is calculated as an output shortage amount.

  Next, when the output of the internal combustion engine 2 is insufficient based on the calculation result in step 124, travel output assist control by the motor 4 is executed (step 126). Specifically, electric energy corresponding to the output shortage calculated in step 124 is supplied from the battery 20 to the motor 4 via the boost converter 19 and the inverter 18, and the motor 4 is driven to Assist driving.

  Since the routine shown in FIG. 7 is the same as the routine shown in FIG. 5 except for the above points, further explanation is omitted here.

  In the present embodiment, the same effects as in the first embodiment described above can be obtained by performing the processing of the routine shown in FIG. That is, even during warming of the exhaust purification catalyst 15, NOx, HC, and CO can be hardly released into the atmosphere, thereby reducing emissions. Moreover, according to this embodiment, since the exhaust purification catalyst 15 is heated by the electric heater 48, the exhaust purification catalyst 15 can be warmed up more quickly. Further, during the catalyst warm-up hydrogen lean operation, since the travel output assist control is performed by the motor 4, even if the output of the internal combustion engine 2 is reduced or the power is consumed by the generator 5, the required travel output is satisfied. be able to. For this reason, warming-up of the exhaust purification catalyst 15 with low emission can be achieved without deteriorating drivability.

  Further, in the present embodiment, since the power of the internal combustion engine 2 is generated when the exhaust purification catalyst 15 is warmed up, even if the required travel output is small, the load on the internal combustion engine 2 is increased to some extent, and the exhaust purification catalyst 15 The exhaust energy flowing into the can be increased. For this reason, even if the required travel output is small, the exhaust purification catalyst 15 can be quickly warmed up in combination with the heating by the electric heater 48. Therefore, the exhaust purification catalyst 15 can be quickly warmed up regardless of the traveling conditions of the vehicle 1 such as when the vehicle 1 is stopped or traveling at a low speed.

  In the second embodiment described above, the electricity generated by the power of the internal combustion engine 2 is supplied to the electric heater 48, but may be supplied from the battery 20 to the electric heater 48.

  In the second embodiment, the generator 5 corresponds to the “generator” in the fifth aspect of the invention. Further, the “catalyst warm-up assisting means” according to the fifth and sixth aspects of the present invention is realized by the ECU 30 executing the process of step 122 described above.

It is a figure for demonstrating the system configuration | structure of the hybrid vehicle of Embodiment 1 of this invention. It is a figure for demonstrating the internal combustion engine mounted in the hybrid vehicle of FIG. It is a figure which shows the relationship between the discharge | emission amount of NOx from an internal combustion engine, and the excess air ratio (lambda). It is a figure which shows the relationship between the magnitude | size of the torque fluctuation which arises in an internal combustion engine, and the excess air ratio (lambda). It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a figure for demonstrating the system configuration | structure of the hybrid vehicle of Embodiment 2 of this invention. It is a flowchart of the routine performed in Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hybrid vehicle 2 Internal combustion engine 3 Power distribution integration mechanism 4 Motor 5 Generator 6 Drive system 7 Front drive shaft 8 Drive wheel 10 Gasoline injector 11 Hydrogen injector 14 Exhaust passage 15 Exhaust purification catalyst 16 Catalyst temperature sensor 18 Inverter 19 Boost converter 20 Battery 22 Vehicle speed sensor 23 Accelerator opening sensor 30 ECU (Electronic Control Unit)
31 Piston 32 Intake valve 33 Exhaust valve 41 Turbocharger 42 Intake passage 44 Throttle valve 45 Air flow meter 48 Electric heater

Claims (6)

A hybrid vehicle comprising an internal combustion engine operable with hydrogen as fuel and another power source,
Hydrogen supply means for supplying hydrogen to the internal combustion engine;
An exhaust purification catalyst disposed in an exhaust passage of the internal combustion engine;
Requested running output calculating means for calculating the requested running output;
A catalyst warm-up hydrogen lean operation means for performing a catalyst warm-up hydrogen lean operation for operating the internal combustion engine with an excess air ratio λ> 1 when the temperature of the exhaust purification catalyst needs to be raised; ,
Assist means for operating the other power source so as to compensate for a shortage of the output of the internal combustion engine with respect to the required travel output during the catalyst warm-up hydrogen lean operation;
A hybrid vehicle comprising:   2. The hybrid vehicle according to claim 1, wherein the excess air ratio λ during the catalyst warm-up hydrogen lean operation is a value such that almost no NOx is discharged from the internal combustion engine. The internal combustion engine can also be operated with liquid fuel,
Liquid fuel supply means for supplying liquid fuel to the internal combustion engine;
Fuel supply switching for operating the liquid fuel supply means and the hydrogen supply means to supply only hydrogen without supplying liquid fuel to the internal combustion engine when the temperature of the exhaust purification catalyst needs to be raised Means,
The hybrid vehicle according to claim 1, further comprising:   The hybrid vehicle according to any one of claims 1 to 3, further comprising an ignition delay means for retarding an ignition timing of the internal combustion engine as compared with a normal time during the catalyst warm-up hydrogen lean operation. . An electric heater capable of heating the exhaust purification catalyst;
Catalyst warm-up auxiliary means for heating the exhaust purification catalyst by energizing the electric heater during the catalyst warm-up hydrogen lean operation;
The hybrid vehicle according to claim 1, further comprising: A generator capable of generating electric power by the power of the internal combustion engine;
The hybrid vehicle according to claim 5, wherein the catalyst warm-up assisting unit energizes the electric heater with electric power generated by the generator.

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