JP2006299826A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To coordinate inhibiting catalyst smell and inhibiting deterioration of a catalyst in an engine intermittently stopped. <P>SOLUTION: An engine ECU executes a program which comprises a step (S1010) of detecting various state quantities of the engine and various state quantities of a vehicle, a step (S1030) of judging whether or not measures for inhibiting the catalyst smell are necessary when measures for inhibiting the deterioration of the catalyst are judged to be necessary (YES at S1020), a step (S1040) of allowing intermittent operation of the engine when the measures for inhibiting the catalyst smell are judged to be necessary (YES at S1030) and a step (S1050) of prohibiting the intermittent operation of the engine when the measures for inhibiting the catalyst smell are not judged to be necessary (NO at S1030). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to control of an internal combustion engine mounted on a vehicle, and more particularly, to an internal combustion engine that coordinates suppression of catalyst odor in exhaust exhausted to the atmosphere after being purified by a catalyst, and suppression of deterioration of the catalyst. Regarding control.

Air pollutants are contained in the exhaust of the engine that is the driving source of the vehicle. Air pollutants combine carbon monoxide (CO) generated when fuel is incompletely combusted, hydrocarbons (HC) vaporized from unburned fuel, and nitrogen and oxygen in the air in a high-temperature combustion chamber. Nitrogen oxide (NOx). These need to be purified before being released to the atmosphere. For this purpose, a catalytic converter is provided in the middle of the exhaust pipe. In this catalytic converter, platinum and rhodium or palladium added thereto is used as a catalyst, so that all three air pollutants are carbon dioxide (CO ₂ ), water (H ₂ O), nitrogen ( N ₂ ). It is also called a three-way catalyst because it reacts with three kinds of chemical substances.

In such a catalytic converter, 1) the catalyst temperature is high, 2) the exhaust gas amount is small (that is, the intake air amount is small), and 3) the average air-fuel ratio after air-fuel ratio control is rich. If a certain condition is satisfied, the inside of the catalytic converter becomes a reducing atmosphere, and a catalyst odor is generated. That is, sulfur (S) contained in the fuel adheres to the catalyst as SOx due to the oxidation action, and when the above three conditions are met, the reduction action of SOx adsorbed under the reducing atmosphere works, and the sulfur odor ( Hydrogen sulfide: H ₂ S) is generated. Specifically, the catalyst odor due to the sulfur compound contained in the fuel is because hydrogen sulfide is generated by the following reaction.

SO ₂ + 3H ₂ → H ₂ S + 2H ₂ O
That is, it is considered that the reason why hydrogen sulfide is generated is that the sulfur component in the fuel burns to become sulfurous acid gas, and this sulfurous acid gas reacts with hydrogen generated in the combustion process.

  As described above, the generation of the catalyst odor based on the fuel property (containing the sulfur component) is more remarkable when the average air-fuel ratio is rich. When the air-fuel ratio is in a lean state, it is considered that sulfur oxides are adsorbed on the catalyst by the following reaction.

2SO ₂ + O ₂ → 2SO ₃
6SO ₃ + 4CeO ₂ → 2Ce ₂ (SO ₄ ) ₃ + O ₂
When the air-fuel ratio is rich, the amount of oxygen is small and the oxygen is combined with hydrogen to form H ₂ O. However, since the amount of oxygen is small, surplus hydrogen is generated and the hydrogen is combined with sulfur to form H _2. It is considered that S is likely to be generated and the generation of the catalyst odor is not suppressed. In this case, when the air-fuel ratio is in a lean state, since there is a lot of oxygen, the oxygen is easily combined with hydrogen to become H ₂ O, and surplus hydrogen is reduced and H ₂ S is difficult to be generated. It is thought that it is done.

In addition to such a catalyst odor (unusual odor), an air-fuel ratio control device that supplies fuel while controlling the ratio of the air-fuel mixture of fuel and air (air-fuel ratio) in the engine to a desired value has been conventionally used. Are known. This air-fuel ratio control device generally sets a target air-fuel ratio according to the operating state, detects the residual oxygen concentration in the exhaust gas with an O ₂ sensor, thereby estimating the actual air-fuel ratio of the fuel, Air-fuel ratio feedback control is performed in which fuel is supplied so that the actual air-fuel ratio matches the target air-fuel ratio.

  Japanese Patent Laid-Open No. 6-307271 (Patent Document 1) discloses an air-fuel ratio control apparatus that can eliminate the problem of off-flavor based on fuel properties and that does not adversely affect air-fuel ratio feedback. The engine air-fuel ratio control device disclosed in this publication includes target air-fuel ratio setting means for setting a target air-fuel ratio of a fuel mixture introduced into the engine, air-fuel ratio detection means for detecting the air-fuel ratio of the mixture, Air-fuel ratio control means for controlling the air-fuel ratio so as to reach the target air-fuel ratio, stop detection means for detecting that the vehicle is stopped, and fuel mixture when detecting that the vehicle is stopped Target air-fuel ratio changing means for changing the target air-fuel ratio so as to make lean.

According to this air-fuel ratio control device, in order to deal with the problem of the off-flavor of the exhaust gas, in the stop state of the vehicle in which the off-flavor is noticeable, the generation of hydrogen sulfide is reduced by forcibly creating a lean state in the air-fuel ratio feedback control. Like to do. In the case where a catalyst is provided, if the catalyst is active, countermeasures against odors by air-fuel ratio feedback control are not performed, and the generation of hydrogen sulfide is suppressed by the catalyst function. When the catalyst activity decreases and the off-flavor becomes a problem, measures against off-flavor by air-fuel ratio feedback control are restored.
JP-A-6-307271

  However, while the catalyst odor is suppressed when the air-fuel ratio is lean, when the air-fuel ratio becomes lean, the specific heat of the air-fuel mixture decreases, the combustion temperature rises, the temperature inside the catalytic converter rises, and thermal degradation occurs. It can be a factor. That is, even if it is attempted to solve the problem by making the generation of the catalyst odor due to the rich state of the air-fuel mixture lean, the problem that the catalyst deteriorates due to the lean state when the air-fuel mixture state becomes lean. appear.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to suppress the generation of a catalyst odor when the internal combustion engine is intermittently stopped during operation of the vehicle. It is providing the control apparatus of a vehicle which coordinates this and suppressing deterioration of a catalyst.

  A control apparatus for an internal combustion engine according to a first aspect of the invention controls an internal combustion engine that is capable of intermittent operation and has an exhaust passage provided with a catalyst device that purifies exhaust gas. The control device, when detecting at least one of the deterioration of the catalyst device and the prediction of the deterioration, means for enriching the air-fuel ratio of the catalyst device in order to satisfy the request for suppressing the deterioration of the catalyst device, When at least one of the generation of the catalyst odor from the device and the prediction of the generation is detected, means for reducing the air-fuel ratio of the catalyst device and the deterioration of the catalyst device are satisfied in order to satisfy the request to suppress the catalyst odor. Control means for determining whether to permit intermittent operation or prohibit intermittent operation based on the request to suppress and the request to suppress the generation of catalyst odor, and to control the internal combustion engine.

  According to the first invention, in a vehicle equipped with an internal combustion engine (engine) that operates in cooperation with an electric motor or a vehicle that temporarily stops the engine in an idling state, the engine is intermittently operated and the engine is intermittently operated. When stopped, the fuel supply to the engine stops immediately, whereas the rotation of the crankshaft does not stop immediately due to inertia, so air is taken in and fuel is not injected, so the air-fuel ratio of the exhaust gas becomes lean . In order to suppress deterioration (thermal deterioration) of the catalyst device, the air-fuel ratio must be made rich, and in order to suppress catalyst odor, the air-fuel ratio must be made lean. Therefore, the control means determines whether to permit intermittent operation or prohibit intermittent operation based on whether suppression of deterioration of the catalyst device or generation of catalyst odor is required. For example, when there is a request to suppress the deterioration of the catalyst device, if there is no request to suppress the generation of the catalyst odor, the intermittent operation is prohibited and the air-fuel ratio of the exhaust gas does not become lean (and the fuel is increased) It is possible to suppress the deterioration of the catalyst device by correcting it to a rich state. In addition, when there is a request to suppress the deterioration of the catalyst device, if there is a request to suppress the generation of the catalyst odor, priority is given to the suppression of the generation of the catalyst odor, permitting intermittent operation, and reducing the air-fuel ratio of the exhaust gas. In a lean state, the generation of catalyst odor can be suppressed. As a result, there is provided a vehicle control device that coordinates the suppression of the generation of the catalyst odor and the suppression of the deterioration of the catalyst when the control for intermittently stopping the internal combustion engine during the operation of the vehicle is performed. can do.

  In the control device for an internal combustion engine according to the second invention, in addition to the configuration of the first invention, the control means has a request to suppress the generation of the catalyst odor when there is a request to suppress the deterioration of the catalyst device. Otherwise, it includes means for prohibiting intermittent operation.

  According to the second invention, when there is a request to suppress the deterioration of the catalyst device, if there is no request to suppress the generation of the catalyst odor, the intermittent operation is prohibited and the air-fuel ratio of the exhaust gas does not become lean ( Furthermore, the deterioration of the catalyst device can be suppressed by increasing the amount of fuel so as to make it rich.

  In the control device for an internal combustion engine according to the third invention, in addition to the configuration of the first invention, the control means has a request to suppress the generation of the catalyst odor when there is a request to suppress the deterioration of the catalyst device. If so, it includes means for allowing intermittent operation.

  According to the third invention, when there is a request to suppress the deterioration of the catalyst device, if there is a request to suppress the generation of the catalyst odor, priority is given to the suppression of the generation of the catalyst odor, and the intermittent operation is permitted and the exhaust is performed. It is possible to suppress the generation of catalyst odor by making the gas air-fuel ratio lean.

  In the control device for an internal combustion engine according to the fourth invention, in addition to the configuration of any one of the first to third inventions, the air-fuel ratio of the catalyst device becomes lean by the control device when intermittent operation is prohibited. Is prohibited.

  According to the fourth invention, when the engine stops intermittently, the fuel supply to the engine stops immediately, whereas the rotation of the crankshaft does not stop immediately due to inertia. Since it is not injected, the air-fuel ratio of the exhaust gas in the catalyst device becomes lean. However, if the intermittent stop of the engine is prohibited, the air-fuel ratio does not become lean, and the engine operation is continued and the fuel is increased to correct the exhaust gas air-fuel ratio in the catalyst device. Thus, the air-fuel ratio of the exhaust gas in the catalyst device can be prohibited from becoming lean.

  In the control device for an internal combustion engine according to the fifth invention, in addition to the configuration of any one of the first to third inventions, when the intermittent operation is permitted, the control device makes the air-fuel ratio of the catalyst device lean. Is.

  According to the fifth aspect, when intermittent operation is permitted and the engine stops intermittently, fuel supply to the engine stops immediately, whereas rotation of the crankshaft does not stop immediately due to inertia. Since the air is sucked and the fuel is not injected, the air-fuel ratio of the exhaust gas in the catalyst device is made lean.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  A control block diagram of a hybrid vehicle to which a control device according to an embodiment of the present invention is applied will be described with reference to FIG. The present invention is not limited to the hybrid vehicle shown in FIG. It may be a hybrid vehicle having another aspect. Further, it may be an electric vehicle or a fuel cell vehicle. In addition, a power storage mechanism such as a capacitor may be used instead of the traveling battery.

  The hybrid vehicle includes an internal combustion engine (hereinafter simply referred to as an engine) 120 such as a gasoline engine or a diesel engine, and a motor generator (MG) 140 as drive sources. In FIG. 1, for convenience of explanation, the motor generator 140 is expressed as a motor 140A and a generator 140B (or a motor generator 140B), but the motor 140A functions as a generator depending on the traveling state of the hybrid vehicle. The generator 140B functions as a motor.

  In the intake passage 122 of the engine 120, an air cleaner 122A that captures dust of intake air, an air flow meter 122B that detects the amount of air sucked into the engine 120 through the air cleaner 122A, and an amount of air sucked into the engine 120 are adjusted. For this purpose, an electronic throttle valve 122C is provided. The electronic throttle valve 122C is provided with a throttle position sensor. The engine ECU 280 receives the intake air amount detected by the air flow meter 122B, the opening degree of the electronic throttle valve 122C detected by the throttle position sensor, and the like.

  Further, in the exhaust passage 124 of the engine 120, a three-way catalytic converter 124B, an air-fuel ratio sensor 124A for detecting an air-fuel ratio (A / F) in the exhaust gas introduced into the three-way catalytic converter 124B, and a three-way catalytic converter 124B. A catalyst temperature sensor 124C for detecting the temperature of the catalyst and a silencer 124D are provided. The engine ECU 280 receives the air-fuel ratio of the exhaust gas introduced into the three-way catalytic converter 124B detected by the air-fuel ratio sensor 124A, the temperature of the three-way catalytic converter 124B detected by the catalyst temperature sensor 124C, and the like.

Air-fuel ratio sensor 124A is a full-range air-fuel ratio sensor (linear air-fuel ratio sensor) that generates an output voltage proportional to the air-fuel ratio of the air-fuel mixture burned by engine 120. The air-fuel ratio sensor 124A may be an O ₂ sensor that detects whether the air-fuel ratio of the air-fuel mixture combusted by the engine 120 is rich or lean with respect to the stoichiometric air-fuel ratio. Good.

  In addition to this, the hybrid vehicle transmits a power generated by the engine 120 and the motor generator 140 to the drive wheels 160, and a reduction gear 180 that transmits the drive of the drive wheels 160 to the engine 120 and the motor generator 140, and the engine 120. Power split mechanism (for example, planetary gear mechanism) 200 that distributes the generated power to two paths of drive wheel 160 and generator 140B, travel battery 220 that charges power for driving motor generator 140, and travel Inverter 240 that performs current control while converting the direct current of battery 220 and the alternating current of motor 140A and generator 140B, and a battery control unit (hereinafter referred to as a battery ECU (Electronic Control Unit)) that manages and controls the charge / discharge state of traveling battery 220 260) and En The engine ECU 280 that controls the operation state of the engine 120, the MG_ECU 300 that controls the motor generator 140, the battery ECU 260, the inverter 240, and the like according to the state of the hybrid vehicle, and the battery ECU 260, the engine ECU 280, the MG_ECU 300, etc. And HV_ECU 320 that controls the entire hybrid system so that the hybrid vehicle can operate most efficiently.

  In the present embodiment, converter 242 is provided between battery for traveling 220 and inverter 240. This is because the rated voltage of the traveling battery 220 is lower than the rated voltage of the motor 140A or the motor generator 140B, and therefore when the power is supplied from the traveling battery 220 to the motor 140A or the motor generator 140B, the converter 242 boosts the power. To do. This converter 242 has a built-in smoothing capacitor, and when the converter 242 performs a boosting operation, electric charge is stored in this smoothing capacitor.

  In FIG. 1, each ECU is configured separately, but may be configured as an ECU in which two or more ECUs are integrated (for example, MG_ECU 300 and HV_ECU 320, as shown by a dotted line in FIG. 1). An example is an integrated ECU).

  The power split mechanism 200 uses a planetary gear mechanism (planetary gear) in order to distribute the power of the engine 120 to both the drive wheel 160 and the motor generator 140B. By controlling the rotation speed of motor generator 140B, power split device 200 also functions as a continuously variable transmission. The rotational force of the engine 120 is input to the planetary carrier (C), which is transmitted to the motor generator 140B by the sun gear (S) and to the motor and the output shaft (drive wheel 160 side) by the ring gear (R). When the rotating engine 120 is stopped, since the engine 120 is rotating, the kinetic energy of this rotation is converted into electric energy by the motor generator 140B, and the rotational speed of the engine 120 is reduced.

  In a hybrid vehicle equipped with a hybrid system as shown in FIG. 1, the hybrid vehicle travels only by the motor 140 </ b> A of the motor generator 140 when the engine 120 is inefficient, such as when starting or running at a low speed. During normal travel, for example, the power split mechanism 200 divides the power of the engine 120 into two paths, and on the other hand, the drive wheels 160 are directly driven, and on the other hand, the generator 140B is driven to generate power. At this time, the motor 140A is driven by the generated electric power to assist driving of the driving wheels 160. Further, at the time of high speed traveling, electric power from the traveling battery 220 is further supplied to the motor 140A to increase the output of the motor 140A and to add driving force to the driving wheels 160. On the other hand, at the time of deceleration, motor 140 </ b> A driven by drive wheel 160 functions as a generator to perform regenerative power generation, and the collected power is stored in traveling battery 220. When the amount of charge of traveling battery 220 decreases and charging is particularly necessary, the output of engine 120 is increased to increase the amount of power generated by generator 140B to increase the amount of charge for traveling battery 220. Of course, there is a case where control is performed to increase the drive amount of the engine 120 as necessary even during low-speed traveling. For example, it is necessary to charge the traveling battery 220 as described above, to drive an auxiliary machine such as an air conditioner, or to raise the temperature of the cooling water of the engine 120 to a predetermined temperature.

  Furthermore, in a hybrid vehicle equipped with a hybrid system as shown in FIG. 1, engine 120 is stopped in order to improve fuel consumption depending on the driving state of the vehicle and the state of traveling battery 220. And after that, the driving | running state of the vehicle and the state of the battery 220 for driving | running | working are detected, and the engine 120 is restarted. In this way, the engine 120 is intermittently operated, and in a conventional vehicle (a vehicle equipped with only an engine), when the ignition switch is turned to the START position and the engine is started, the ignition switch is switched from the ON position to the ACC position. Or it is different in that the engine does not stop until it is in the OFF position.

  Stopping engine 120 in the present embodiment is for the purpose of improving fuel efficiency. For example, when a stop command for engine 120 is output from HV_ECU 320 to engine ECU 280, fuel supply to engine 120 is immediately cut off. Is done. At this time, even if the fuel supply to the engine 120 is stopped and power is not transmitted from the motor generator and the drive wheels 160 to the engine 120, the engine 120 has inertia, so that the crankshaft of the engine 120 immediately rotates. It does not stop. When the crankshaft is rotating, the intake valve and the exhaust valve are opened and closed, and air is sucked into the engine 120 but fuel is not supplied, so that the exhaust from the engine 120 becomes lean.

  When it is determined that the control device according to the embodiment of the present invention needs to suppress the deterioration of the three-way catalytic converter 124B (to make it rich), it is determined that the countermeasure for the catalyst odor is not necessary ( It may be in a rich state), and is characterized by prohibiting intermittent operation and setting the air-fuel ratio of the exhaust gas to a rich state so as not to be at least lean. Further, even when it is necessary to suppress the deterioration of the three-way catalytic converter 124B (to make it rich), if it is determined that countermeasures against the catalyst odor are necessary (to make it lean), measures against the catalyst odor It is characterized in that intermittent operation is permitted with priority given to the above, and the air-fuel ratio of the exhaust gas is made lean. The engine ECU 280 determines such prohibition and permission of intermittent operation, sets the engine stop request flag to a set state or a reset state, and transmits the flag to the HV_ECU 320.

  With reference to FIG. 2, a control structure of a program executed by engine ECU 280 which is an example of a control device according to the embodiment of the present invention will be described.

  In step (hereinafter, step is abbreviated as S) 1010, engine ECU 280 detects various state quantities of engine 120 and various state quantities of the vehicle. At this time, the amount of air sucked into the engine 120, the amount of fuel supplied to the engine 120, the air-fuel ratio detected by the air-fuel ratio sensor 124A, and the temperature of the three-way catalytic converter 124B detected by the catalyst temperature sensor 124C. Are detected. Further, engine ECU 280 can detect a time change of these detected values, or integrate these detected values with time to detect the time integrated value. Moreover, you may make it detect the time change of the set state and reset state of an engine stop request flag.

  In S1020, engine ECU 280 determines whether or not a catalyst deterioration suppression measure is necessary. At this time, the process for determining that measures for suppressing the catalyst deterioration are necessary corresponds to detecting at least one of the deterioration of the three-way catalytic converter 124B and the prediction of the deterioration. At this time, for example, the time during which the exhaust gas is lean is longer than a predetermined time, the integrated value of the intake air amount exceeds a predetermined value, or the temperature of the three-way catalytic converter 124B is If the temperature is higher than a predetermined temperature (the time that is higher than that temperature is longer than a predetermined time), the exhaust gas is lean and the temperature of the exhaust gas is high. Since the temperature of the original catalytic converter 124B is high, it is determined that the three-way catalytic converter 124B may be deteriorated due to heat, and it is determined that a measure for suppressing catalyst deterioration is necessary. Even if the amount of fuel supplied to the engine 120 is corrected to increase, when a sufficient time has passed after that, since the exhaust gas is not in a rich state but in a lean state, the temperature of the exhaust gas is It is determined that deterioration of the three-way catalytic converter 124B is likely to occur, and it is determined that measures for suppressing catalyst deterioration are necessary. If it is determined that a catalyst deterioration suppression measure is necessary (YES in S1020), the process proceeds to S1030 (the exhaust gas needs to be rich). If not (NO in S1020), the process proceeds to S1040 (the exhaust gas state may remain lean).

  In S1030, engine ECU 280 determines whether or not a countermeasure for suppressing catalyst odor is required. At this time, the process for determining that the countermeasure for suppressing the catalyst odor is necessary corresponds to detecting at least one of the generation of the catalyst odor from the three-way catalytic converter 124B and the prediction of the generation. At this time, for example, if the time during which the exhaust gas is rich is equal to or longer than a predetermined time, it is determined that the catalyst odor of the three-way catalytic converter 124B can be generated, and a countermeasure for suppressing the catalyst odor is necessary. It is judged. Further, after the fuel supplied to the engine 120 has been corrected for the increase, and when a sufficient time has not elapsed thereafter, the exhaust gas is still in a rich state. It is determined that an odor can be generated, and it is determined that a catalyst odor suppression measure is necessary. Conversely, after the fuel supplied to the engine 120 has been corrected for increase, and when a sufficient time has passed since then, the exhaust gas is not in a rich state but in a lean state. It is determined that the catalyst odor cannot be generated from the three-way catalytic converter 124B, and it is not determined that a measure for suppressing the catalyst odor is necessary. If it is determined that a catalyst odor suppression measure is necessary (YES in S1030), the process proceeds to S1040 (the exhaust gas needs to be made lean). If not (NO in S1030), the process proceeds to S1050 (the exhaust gas state may remain rich).

  In S1040, engine ECU 280 sets a stop request flag for engine 120 (in a Hi state or an ON state), and performs permission processing for intermittent operation of engine 120.

  In S1050, engine ECU 280 resets the stop request flag of engine 120 (Lo state or OFF state), and performs a process for prohibiting intermittent operation of engine 120.

  This engine stop request flag is transmitted from engine ECU 280 to HV_ECU 320 and used in HV_ECU 320. That is, when an engine stop request flag is transmitted from engine ECU 280 to HV_ECU 320 and HV_ECU 320 satisfies a predetermined engine stop condition, based on the state (set state / reset state) of this engine stop request flag. , HV_ECU 320 transmits to engine ECU 280 a command to actually stop engine 120 or not to stop engine 120 for intermittent operation of engine 120.

  The engine stop request flag may be used in engine ECU 280 without being transmitted from engine ECU 280 to HV_ECU 320. That is, whether engine ECU 280 itself actually stops engine 120 based on the engine stop command for intermittent operation of engine 120 received from HV_ECU 320 and the state (set state / reset state) of this stop request flag. It will be judged whether or not.

  The operation of engine 120 controlled by engine ECU 280, which is a control device according to the present embodiment based on the structure and flowchart as described above, will be described.

  While the hybrid vehicle is running (whether the engine 120 is operating or stopped, the following description assumes that the engine 120 is operating) and various state quantities of the engine 120 and various types of vehicles A state quantity, its time change, or a time integration value is detected.

  If measures for suppressing deterioration of three-way catalytic converter 124B are required (YES at S1020) and measures for suppressing catalyst odor of three-way catalytic converter 124B are also required (YES at S1030), intermittent operation of engine 120 is permitted. Then, the air-fuel ratio of the exhaust gas is allowed to be in a lean state to suppress the catalyst odor, and the engine stop request flag is set (S1040). This state is shown as state (A) in FIG.

  Further, although measures for suppressing deterioration of three-way catalytic converter 124B are required (YES in S1020) and measures for suppressing catalyst odor of three-way catalytic converter 124B are not required (NO in S1030), intermittent operation of engine 120 is performed. Prohibited (To make the exhaust gas air-fuel ratio lean, there is no need to suppress the catalyst odor, so it is not necessary to make the exhaust gas air-fuel ratio rich in order to suppress catalyst deterioration. The engine stop request flag is reset (S1050). This state is shown as state (B) in FIG.

  Further, if measures for suppressing deterioration of three-way catalytic converter 124B are not required (NO in S1020), intermittent operation of engine 120 is permitted (exhaust gas) regardless of whether or not measures for suppressing catalyst odor of three-way catalytic converter 124B are necessary. An engine stop request flag is set (S1040) when the air-fuel ratio of the gas is allowed to be in a lean state in order to suppress the catalyst odor. This state is shown as state (C) in FIG.

  When the engine stop request flag is set (S1040) as in the states (A) and (C) shown in FIG. 3, the engine ECU 280 is in the set state indicating that the HV_ECU 320 permits the intermittent operation of the engine 120. A certain engine stop request flag is transmitted. When the engine stop condition in the intermittent operation of engine 120 is satisfied, HV_ECU 320 outputs an engine stop command for stopping engine 120 to engine ECU 280 because the engine stop request flag is set.

  Although the fuel supply to the engine 120 is stopped based on the stop command of the engine 120, the crankshaft of the engine 120 rotates by inertia, air is introduced from the intake valve into the engine 120, and the exhaust gas state is lean. It becomes a state. When the exhaust gas becomes lean, the generation of catalyst odor is suppressed.

  On the other hand, when the engine stop request flag is reset as in the state (B) shown in FIG. 3 (S1050), the engine ECU 280 is in the reset state indicating that the HV_ECU 320 prohibits the intermittent operation of the engine 120. Send a stop request flag. Even if the engine stop condition in the intermittent operation of engine 120 is satisfied, HV_ECU 320 does not output an engine stop command for stopping engine 120 to engine ECU 280 because the engine stop request flag is in a reset state.

  Since the stop of fuel supply to the engine 120 based on the stop command of the engine 120 is not executed, the fuel is supplied to the engine 120, and at least the state of the exhaust gas does not become a lean state. Since the exhaust gas does not become lean, deterioration of the three-way catalytic converter is suppressed.

  As described above, according to the engine ECU that is the control device according to the present embodiment, it is necessary to take measures for suppressing deterioration of the three-way catalytic converter based on the state of the engine and the operating state of the vehicle (exhaust gas Even if it is determined that the state needs to be rich), if it is determined that the catalyst odor control measures of the three-way catalytic converter are necessary, the intermittent operation of the engine is prohibited and the exhaust gas state is rich. Instead, allow intermittent operation of the engine and prioritize countermeasures against catalyst odor to make the exhaust gas lean. In this way, even if there is a catalyst deterioration suppression request, if there is a catalyst odor suppression request, intermittent operation is permitted and the exhaust gas state is made lean so that the catalyst odor can be suppressed. . In particular, the catalyst odor felt immediately for the user can be suppressed.

  The present invention can be applied to the following vehicles instead of the hybrid vehicle described above. For example, when the vehicle stops at a red light at an intersection or the like, the engine is automatically stopped and the driver operates to start driving again (for example, depressing the accelerator pedal, stopping the brake pedal, The vehicle may be equipped with an idling stop system that restarts the engine when the lever is switched to the forward travel position. When the engine is restarted, the engine is restarted by rotating the crankshaft by an electric motor such as a motor generator or a starter motor using the power of the secondary battery mounted on the vehicle. In application of the present invention to the idling stop system, idling stop control is prohibited when the engine stop request flag is reset.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a control block diagram of the hybrid vehicle which concerns on embodiment of this invention. It is a flowchart which shows the control structure of the engine stop permission process performed with engine ECU. It is a figure which shows the cooperative relationship of a catalyst degradation suppression measure and a catalyst odor suppression measure.

Explanation of symbols

  120 engine, 122 intake passage, 122A air cleaner, 122B air flow meter, 122C electronic throttle valve, 124 exhaust passage, 124A air-fuel ratio sensor, 124B three-way catalytic converter, 124C catalyst temperature sensor, 124D silencer, 140 motor generator, 140A motor, 140B generator, 142 temperature sensor, 160 driving wheel, 180 speed reducer, 200 power split mechanism, 220 battery for traveling, 240 inverter, 242 converter, 260 battery ECU, 280 engine ECU, 300 MG_ECU, 320 HV_ECU.

Claims (5)

A control device for an internal combustion engine capable of intermittent operation,
A catalyst device for purifying exhaust gas is provided in the exhaust passage of the internal combustion engine,
The control device includes:
Means for making the air-fuel ratio of the catalyst device rich in order to satisfy the requirement to suppress the deterioration of the catalyst device upon detecting at least one of deterioration of the catalyst device and prediction of deterioration;
Means for making the air-fuel ratio of the catalyst device lean in order to satisfy the requirement to suppress the catalyst odor upon detecting at least one of the generation of the catalyst odor from the catalyst device and the prediction of the generation thereof;
Based on the request to suppress the deterioration of the catalyst device and the request to suppress the generation of the catalyst odor, it is determined whether to permit the intermittent operation or prohibit the intermittent operation, and to control the internal combustion engine A control device for an internal combustion engine, comprising control means.   2. The control unit according to claim 1, wherein the control unit includes a unit for prohibiting the intermittent operation when there is a request to suppress the generation of the catalyst odor when there is a request to suppress deterioration of the catalyst device. Control device for internal combustion engine.   2. The control unit according to claim 1, wherein the control unit includes a unit for permitting the intermittent operation when there is a request to suppress the generation of the catalyst odor when there is a request to suppress deterioration of the catalyst device. Control device for internal combustion engine.   The control device for an internal combustion engine according to any one of claims 1 to 3, wherein when the intermittent operation is prohibited, the control device prohibits the air-fuel ratio of the catalyst device from becoming lean.   The control device for an internal combustion engine according to any one of claims 1 to 3, wherein when the intermittent operation is permitted, the air-fuel ratio of the catalyst device is made lean by the control device.

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