JP2015129455A - Hybrid electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an increase in NOx emission at a time of regenerating a NOx storage reduction catalyst.SOLUTION: A hybrid electric vehicle 1 comprises: an engine 10; a motor generator 20; a three-way catalyst 81 and a NOx storage reduction catalyst 82; and a control unit 100. The control unit 100 is configured to execute a catalyst regeneration operation for regenerating the NOx storage reduction catalyst 82 by operating the engine 10 in a rich state of an air-fuel ratio of the engine 10. The control unit 100 executes a NOx suppression transition control to change the air-fuel ratio of the engine 10 from an air-fuel ratio corresponding to the operation before transition to an air-fuel ratio corresponding to the operation after the transition during operation transition for transitioning a lean operation to the catalyst regeneration operation or during operation transition for transitioning the catalyst regeneration operation to the lean operation, and to advance the timing of injecting a fuel into the engine 10 with respect to the timing during the operation before the transition and the timing during the operation after the transition while the air-fuel ratio of the engine 10 is changing.

Description

  The technology disclosed here relates to a hybrid vehicle including a NOx storage reduction catalyst.

  Conventionally, a hybrid vehicle in which an NOx storage reduction catalyst is provided in an exhaust passage is known. For example, in the hybrid vehicle according to Patent Document 1, when the NOx occlusion amount of the catalyst increases, the NOx occlusion reduction catalyst is regenerated. In the regeneration of the NOx storage reduction catalyst, a rich operation in which the air-fuel ratio becomes rich is performed, and NOx stored in the catalyst is reduced by the fuel.

JP 2008-68802 A

  However, when shifting from a lean operation where the air-fuel ratio is lean to a rich operation during regeneration of the NOx storage reduction catalyst, the NOx emission amount may temporarily increase. The regeneration of the NOx occlusion reduction catalyst is performed when there is not much room for NOx occlusion by the NOx occlusion reduction catalyst, so it is not preferable that the NOx emission amount increase at this timing.

  The technology disclosed here suppresses an increase in the NOx emission amount when the NOx storage reduction catalyst is regenerated.

  The hybrid vehicle disclosed herein includes an engine, a motor generator that is driven by the engine to generate electric power, a three-way catalyst and a NOx occlusion reduction catalyst provided in an exhaust system of the engine, the engine and the motor generator. A control unit that controls the NOx occlusion reduction catalyst by reducing the NOx occluded in the NOx occlusion reduction catalyst by operating the engine while the air-fuel ratio of the engine is rich. The catalyst regeneration operation is performed to regenerate the engine, and the operation shifts from the lean operation in which the engine is operating in a leaner state than the catalyst regeneration operation to the catalyst regeneration operation. At the time of operation transition, or at the time of operation transition to shift from the catalyst regeneration operation to the lean operation, the operation before shifting the air-fuel ratio of the engine While the air-fuel ratio of the engine is changing from the corresponding air-fuel ratio to the air-fuel ratio corresponding to the operation after the transition, the fuel injection timing to the engine is changed from the operation before the transition and the operation after the transition. It is assumed that the NOx suppression shift control for advancing is also executed.

  According to the above configuration, the three-way catalyst and the NOx storage reduction catalyst are provided in the exhaust passage. The three-way catalyst has different NOx purification characteristics depending on the air-fuel ratio. For example, a three-way catalyst exhibits high purification performance at a stoichiometric air-fuel ratio, and has a low NOx purification capacity in an environment where the air-fuel ratio is lean. Therefore, by providing the NOx storage reduction catalyst, it is possible to purify NOx in various operating states including lean operation.

  As the NOx storage amount increases, the NOx storage reduction catalyst eventually needs to perform a catalyst regeneration operation. In the catalyst regeneration operation, the air-fuel ratio of the engine is made rich, and NOx stored in the NOx storage reduction catalyst is reduced by the fuel.

  By the way, NOx discharged from the combustion chamber of the engine increases in the operating state near the theoretical air-fuel ratio, and decreases as the air-fuel ratio becomes leaner. Further, the purification performance of the three-way catalyst is high near the stoichiometric air-fuel ratio, and decreases as the air-fuel ratio becomes leaner. However, in the operation state where the air-fuel ratio is lean near the stoichiometric air-fuel ratio, the reduction in the purification performance of the three-way catalyst is larger than the reduction in NOx discharged from the combustion chamber. The quantity increases in lean operating conditions near the stoichiometric air / fuel ratio. In other words, due to the relationship between the NOx emission amount from the combustion chamber with respect to the air-fuel ratio of the engine and the NOx purification performance of the three-way catalyst with respect to the air-fuel ratio of the engine, the NOx emission amount downstream of the three-way catalyst depends on the air-fuel ratio of the engine. There are cases where it cannot be reduced sufficiently.

  In the catalyst regeneration operation, since the air-fuel ratio of the engine is rich, the NOx exhausted from the combustion chamber is low or the purification performance of the three-way catalyst is high. Few. However, when shifting to the catalyst regeneration operation, or when shifting from the catalyst regeneration operation, when the operation state after the transition is a lean operation state, In some cases, the air-fuel ratio temporarily becomes an air-fuel ratio (for example, a lean air-fuel ratio in which the air-fuel ratio is close to the stoichiometric air-fuel ratio) at which the amount of NOx emission downstream of the three-way catalyst increases. As a result, the NOx emission amount downstream of the three-way catalyst may increase.

  On the other hand, in the above configuration, when shifting from the lean operation to the catalyst regeneration operation, or when shifting from the catalyst regeneration operation to the lean operation, the engine air-fuel ratio is changed from the air-fuel ratio corresponding to the operation before the transition after the transition. The air-fuel ratio corresponding to the operation is changed, and while the air-fuel ratio is changing, NOx suppression transition control is performed to advance the fuel injection timing more than during the operation before the transition and during the operation after the transition. Since the air-fuel ratio of the engine is changed from the air-fuel ratio corresponding to the operation before the transition to the air-fuel ratio corresponding to the operation after the transition, the engine air-fuel ratio temporarily changes to the air-fuel ratio where the NOx emission amount downstream of the three-way catalyst increases. It becomes like. However, at this time, the combustion supply timing is advanced, that is, the fuel is supplied early, so that the fuel and air are mixed more uniformly. Thereby, generation | occurrence | production of NOx by local rapid combustion can be suppressed. As a result, an increase in NOx emission from the combustion chamber can be suppressed.

  Further, the control unit may increase the advance amount of the fuel injection timing at the time of the operation transition as the air-fuel ratio of the engine becomes richer.

  As the amount of fuel with respect to the amount of air increases, the problem of uneven distribution of fuel in the cylinder increases. According to the above-described configuration, the fuel injection timing is advanced as the fuel amount with respect to the air amount increases, so that the air-fuel mixture can be made homogeneous despite the increase in the air-fuel ratio.

  Furthermore, the control unit may retard the ignition timing of the engine according to the air-fuel ratio of the engine and the advance amount of the fuel injection timing at the time of the transition to operation.

  According to the above configuration, the ignition timing is retarded according to the air-fuel ratio and the fuel injection timing. As a result, it is possible to realize an appropriate engine operation state according to the air-fuel ratio and the fuel injection timing, and it is possible to reduce a sudden change in the engine speed when the air-fuel ratio changes.

  Further, in the NOx suppression control, the control unit gradually changes the operating state of the engine so that the air-fuel ratio of the engine changes from the air-fuel ratio corresponding to the operation before the transition to the air-fuel ratio corresponding to the operation after the transition. And the advance amount of the fuel injection timing is adjusted in accordance with the air-fuel ratio of the engine, and the SOC of the battery is not less than a predetermined first capacity and the required power generation amount is a predetermined amount. When the power generation amount is equal to or less than the first power generation amount, the NOx suppression shift control is executed. On the other hand, when the SOC of the battery is smaller than the first capacity or the required power generation amount is larger than the first power generation amount, the operation transition is performed. Sometimes, the engine air-fuel ratio changes from an air-fuel ratio corresponding to the operation before the transition to an air-fuel ratio corresponding to the operation after the transition in a shorter period than the NOx suppression transition control. You may perform normal transition control to change the operating condition.

  According to the above configuration, when the state of charge of the battery is bad (that is, when the SOC is smaller than the first capacity) or when the required power generation amount (hereinafter referred to as “required power generation amount”) is large (that is, the request When the power generation amount is larger than the first power generation amount), the normal transition control is performed instead of the NOx suppression transition control at the time of operation transition. Compared to NOx suppression transition control, the normal transition control completes the catalyst regeneration operation because the period during which the engine air-fuel ratio changes from the air-fuel ratio corresponding to the operation before the transition to the air-fuel ratio corresponding to the operation after the transition is shorter. The time until returning to power generation operation is shortened. As a result, the battery can be charged as quickly as possible.

  Further, the control unit executes the catalyst regeneration operation when the NOx occlusion amount of the NOx occlusion reduction catalyst is equal to or greater than a predetermined first occlusion amount, and the NOx occlusion amount of the NOx occlusion reduction catalyst is the first occlusion amount. Even when the storage amount is smaller than the storage amount, the NOx storage amount is not less than the second storage amount smaller than the first storage amount and the SOC of the battery is not more than the second capacity larger than the first capacity. Sometimes, the catalyst regeneration operation may be executed while performing the NOx suppression transition control.

  According to the above configuration, the catalyst regeneration operation is basically executed when the storage amount of NOx is equal to or greater than the first storage amount. However, even if the NOx storage amount does not reach the first storage amount, the NOx storage amount is somewhat large (that is, the NOx storage amount is greater than or equal to the second storage amount) and the battery is in a poorly charged state. When the condition is larger than the normal transition control condition (that is, the SOC is equal to or less than the second capacity larger than the first capacity), the catalyst regeneration operation with the NOx suppression transition control is executed. That is, even if the NOx occlusion amount is such that the catalyst regeneration operation is not normally performed, the NOx occlusion amount immediately reaches the execution condition of the catalyst regeneration operation, and the SOC of the battery immediately becomes the normal transition control. In the case where it is predicted that the NOx suppression shift control cannot be executed due to a decrease to the execution condition, the catalyst regeneration operation with the NOx suppression shift control is executed in advance. Thereby, catalyst regeneration operation with improved emission performance can be performed.

  According to the hybrid vehicle, it is possible to suppress an increase in NOx emission when the NOx storage reduction catalyst is regenerated.

It is the schematic of a hybrid vehicle. It is a figure which shows the engine and control system of a hybrid vehicle. It is the first half part of the flowchart of a catalyst regeneration operation. It is the second half part of the flowchart of a catalyst regeneration operation. It is a time chart of the catalyst regeneration operation accompanied by NOx suppression transition control, (A) shows the excess air ratio, (B) shows the fuel injection timing, and (C) shows the ignition timing. It is a time chart of the catalyst regeneration operation with normal transition control, (A) shows the excess air ratio, (B) shows the fuel injection timing, and (C) shows the ignition timing.

  Hereinafter, exemplary embodiments will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram of a hybrid vehicle 1 (hereinafter referred to as “vehicle 1”). FIG. 2 is a diagram illustrating an engine and a control system of the hybrid vehicle.

  This vehicle 1 is a so-called series-type hybrid vehicle, in which an engine 10 and a rotating shaft are connected to an output shaft (an eccentric shaft 13 described later) of the engine 10 to drive and start the engine 10 and A motor generator 20 that is driven by the engine 10 after starting to generate electric power, a high-voltage / large-capacity battery 30 that stores (charges) the electric power generated by the motor generator 20, and the engine 10 is driven. And a traveling motor 40 driven by at least one of the electric power generated by the motor generator 20 and the stored electric power (discharge power) of the battery 30.

  An inverter 50 is provided between the motor generator 20, the battery 30, and the traveling motor 40. Via the inverter 50, the power generated by the motor generator 20 is supplied to the battery 30 and / or the traveling motor 40, and the discharged power from the battery 30 is supplied to the motor generator 20 and / or the traveling motor 40. Is done.

  The traveling motor 40 is driven by being supplied with at least one of the generated power of the motor generator 20 and the discharged power from the battery 30. The driving force of the traveling motor 40 is transmitted to the left and right front wheels 61 as driving wheels via the differential device 60, whereby the vehicle 1 travels. The traveling motor 40 is capable of generating regenerative generated power, and operates as a generator when the vehicle 1 is decelerated, and the generated power (regenerative generated power) is charged in the battery 30. The battery 30 can be externally charged by a power source external to the vehicle 1.

  Engine 10 is used only for power generation by motor generator 20. In this embodiment, the engine 10 is a hydrogen engine in which hydrogen gas stored in the hydrogen tank 70 is supplied as fuel.

  As shown in FIG. 2, the engine 10 is a twin-rotor (two-cylinder) rotary piston engine, and is roughly arranged in a rotor housing chamber 11 a formed in two saddle-shaped rotor housings 11 (inside cylinders). Each of the triangular rotors 12 is accommodated. The two rotor housings 11 are integrated with the side housings so as to be sandwiched between three side housings (not shown), and each rotor housing chamber 11a is composed of each rotor housing 11 and the side housings on both sides thereof. Is formed. In FIG. 2, the two rotor housings 11 (two cylinders) are shown in an unfolded state, and the eccentric shafts 13 respectively drawn in the central portions in the two rotor housings 11 are the same.

  Each of the rotors 12 has apex seals (not shown) at the apexes of the triangles, and these apex seals are in sliding contact with the inner surface of the trochoid of the rotor housing 11. Three working chambers (corresponding to combustion chambers) are defined in 11a (in each cylinder). Each rotor 12 rotates around the eccentric shaft 13 in a state where the three apex seals of the rotor 12 are in contact with the inner peripheral surface of the trochoid of the rotor housing 11, and around the axis of the eccentric shaft 13. To revolve around. While the rotor 12 makes one revolution, the working chambers formed between the tops of the rotor 12 move in the circumferential direction, and the intake, compression, expansion (combustion), and exhaust strokes are performed. The rotating force is output from the eccentric shaft 13 as the output shaft through the rotor 12.

  Each rotor accommodating chamber 11a communicates with an intake passage 14 so as to communicate with the working chamber in the intake stroke, and an exhaust passage 15 communicates with the working chamber in the exhaust stroke. There is one intake passage 14 on the upstream side, but on the downstream side, the intake passage 14 branches into two branch passages and communicates with each of the rotor accommodating chambers 11a. A throttle valve 16 that is driven by a throttle valve actuator 90 such as a stepping motor to adjust the cross-sectional area (valve opening) of the intake passage 14 is disposed upstream of the branch portion of the intake passage 14. A premixing injector 17 (fuel injection valve) for injecting hydrogen (fuel) supplied from the hydrogen tank 70 into the intake passage 14 is disposed in each branch passage downstream of the branch portion of the intake passage 14. It is installed. The hydrogen injected by the premixing injector 17 is supplied to the working chamber in the intake stroke in a state of being mixed with air (premixed state).

  Two exhaust passages 15 are provided on the upstream side so as to communicate with the respective rotor accommodating chambers 11a, but are joined together on the downstream side. A three-way catalyst 81 and a NOx occlusion reduction catalyst (hereinafter referred to as “NOx catalyst”) 82 for purifying exhaust gas are disposed downstream of the merging portion of the exhaust passage 15. Further, an air-fuel ratio sensor 105 is provided in the exhaust passage 15 on the upstream side of the three-way catalyst 81. In FIG. 2, arrows shown in the intake passage 14 and the exhaust passage 15 indicate the flow of intake and exhaust.

  In each rotor housing 11 (each cylinder), a direct injection injector 18 (fuel injection valve) that directly injects hydrogen (fuel) supplied from the hydrogen tank 70 into the rotor accommodating chamber 11a (inside the cylinder); An ignition plug 19 is provided for igniting the hydrogen injected from the premixing injector 17 or the direct injection injector 18.

  The premixing injector 17 operates when the temperature of engine cooling water (engine water temperature) detected by an engine water temperature sensor 106 described later is lower than a preset temperature. On the other hand, the direct injection injector 18 operates when the engine water temperature is equal to or higher than the set temperature. This is because when the engine water temperature is lower than the set temperature, the water vapor generated when the fuel (hydrogen) burns freezes at the injection port of the direct injection injector 18 and the injection port may be blocked. . Further, the ice adhering to the inner peripheral surface of the trochoid of the rotor housing 11 is scraped into the injection port of the direct injection injector 18 by the apex seal of the rotor 12, and this also blocks the injection port of the direct injection injector 18. There is a case. When the injection hole of the direct injection injector 18 is thus closed, the amount of fuel supplied into the rotor accommodating chamber 11a is insufficient. Therefore, in order to prevent a shortage of the amount of fuel supplied into the rotor accommodating chamber 11a due to icing, when the engine water temperature is at a temperature at which icing occurs at the injection port of the direct injection injector 18, the premixing injector 17 To inject fuel. When the engine water temperature is equal to or higher than the set temperature, the ice in the injection port of the direct injection injector 18 melts and the water vapor generated when the fuel (hydrogen) burns does not freeze, so the air filling rate is reduced. Hydrogen is injected from the direct injection injector 18 so that high torque can be obtained by increasing the pressure.

  Here, when the engine 10 is started, the engine water temperature immediately before the previous engine stop is usually equal to or higher than the set temperature, and the water vapor generated immediately before the engine stops evaporates. Even if the engine water temperature is lower than the set temperature, there is a low possibility that ice is present in the injection hole of the direct injection injector 18. Therefore, fuel is injected from the direct injection injector 18 in order to improve the startability of the engine 10. Even after the engine 10 is started, if the engine water temperature is lower than the set temperature, the direct injection injector 18 is switched to the premixing injector 17.

  In the present embodiment, only one premixing injector 17 is provided in each branch path, but the direct injection injector 18 is provided in each rotor housing 11 in the axial direction of the eccentric shaft 13 (the surface of FIG. 2). Are arranged side by side (in FIG. 2, only one is visible).

  The vehicle 1 includes a battery current / voltage sensor 101 that detects a current flowing into and out of the battery 30 and a voltage of the battery 30, and an accelerator that detects an amount of depression of an accelerator pedal by a driver of the vehicle 1 (accelerator opening by a driver's operation). The opening sensor 102, the vehicle speed sensor 103 for detecting the vehicle speed of the vehicle 1, the rotation angle sensor 104 provided on the eccentric shaft 13 for detecting the rotation angle position of the eccentric shaft 13, and the air-fuel ratio of the exhaust gas of the engine 10 are determined. An air-fuel ratio sensor 105 for detecting, an engine water temperature sensor 106 for detecting a temperature (engine water temperature) of engine cooling water flowing in the water jacket facing a water jacket (not shown) formed in the rotor housing 11; , The pressure in the hydrogen tank 70 (that is, the hydrogen tank A tank pressure sensor 107 for detecting the remaining amount of hydrogen in the air), an air flow sensor 108 for detecting the intake flow rate drawn into the intake passage 14, a battery temperature sensor 109 for detecting the temperature of the battery 30, and the engine 10 A control unit 100 that performs operation control, operation control of the inverter 50 (that is, operation control of the motor generator 20 and the traveling motor 40), and the like is provided.

  The intake flow rate detected by the air flow sensor 108 corresponds to the amount of air filled into each cylinder of the engine 10. The rotation angle sensor 104 also serves as an engine speed sensor that detects the speed of the engine 10 (hereinafter referred to as engine speed). Further, the air-fuel ratio of the exhaust gas detected by the air-fuel ratio sensor 105 corresponds to the actual air-fuel ratio of the engine 10.

  The control unit 100 is a controller based on a well-known microcomputer, and includes a central processing unit (CPU) that executes a program, a memory that is configured by, for example, a RAM or ROM, and stores a program and data, and an electrical signal An input / output (I / O) bus. The control unit 100 includes a battery current / voltage sensor 101, an accelerator opening sensor 102, a vehicle speed sensor 103, a rotation angle sensor 104, an air-fuel ratio sensor 105, an engine water temperature sensor 106, a tank pressure sensor 107, an air flow sensor 108, a battery temperature sensor. Various signals from 109 and the like are input. The control unit 100 is an example of a control unit.

  Based on the input signal, the control unit 100 outputs a control signal to the throttle valve actuator 90, the port injection injector 17, the direct injection injector 18, and the spark plug 19 to control the engine 10, A control signal is output to the inverter 50 to control the motor generator 20 and the traveling motor 40.

  The inverter 50 generates an operating state of the motor generator 20 by driving the engine 10 by generating driving torque by supplying electric power from the battery 30, and generating electric power by driving the engine 10 to generate the generated electric power in the battery 30 or the traveling state. It has the function to switch to the power generation state supplied to the motor 40. Then, the control unit 100 controls the inverter 50 to start the engine 10 with the operating state of the motor generator 20 as the driving state when the engine 10 is started. After the engine 10 is started, the control unit 100 switches to the power generation state. When the motor generator 20 is in the power generation state, the power generated by the motor generator 20 can be changed by changing the absorption torque of the motor generator 20 under the control of the inverter 50. The inverter 50 can also make the motor generator 20 in an idle state where the engine 10 is not driven and does not generate electricity (a state where the absorption torque of the motor generator 20 is zero). When the motor generator 20 is idled by controlling the engine, the engine 10 enters a no-load operation state where no load is applied. On the other hand, when the motor generator 20 is in the power generation state, the engine 10 enters a loaded operation state in which a load due to the power generation operation of the motor generator 20 is applied.

  Inverter 50 further includes a first mode in which driving motor 40 is driven only with the discharged power from battery 30, a second mode in which only the generated power from motor generator 20 is driven, and battery 30 and motor generator. 20 has a function capable of switching to the third mode performed with the power from both.

  The control unit 100 detects the remaining capacity (SOC) of the battery 30 based on the current flowing into and out of the battery 30 and the voltage of the battery 30 detected by the battery current / voltage sensor 101. The control unit 100 preferentially uses the first aspect when the SOC of the battery 30 is high, and preferentially uses the second aspect or the third aspect when the SOC is low. Here, the second mode includes a case where all of the generated power is consumed by the traveling motor 40 and a case where the generated power is used for both the consumption of the traveling motor 40 and the charging of the battery 30. In the former case, the traveling motor 40 is driven while maintaining the SOC, and in the latter case, the traveling motor 40 is driven while increasing the SOC (while charging). The situation of the third aspect includes a scene where the driver's acceleration request is large based on input information from the accelerator opening sensor 102 or the like, or a case where the dischargeable power of the battery 30 is low. The first mode is selected when the remaining amount of hydrogen in the hydrogen tank 70 by the tank pressure sensor 107 becomes a predetermined value or less, or when the engine 10 is overheated.

  Based on the power generation request, the control unit 100 causes the engine 10 to drive the motor generator 20 to generate power (this operation is hereinafter referred to as “power generation operation”). The power generation request is issued, for example, when the dischargeable power of the battery 30 is low or when the driver's acceleration request is large. Further, the required power generation amount varies depending on the dischargeable power of the battery 30 or the magnitude of the driver's acceleration request.

  During power generation operation, the control unit 100 operates the engine 10 at a lean air-fuel ratio (for example, an excess air ratio λ = 2.3) that is leaner than the stoichiometric air-fuel ratio in order to improve fuel efficiency. At this time, the engine 10 is operated at a constant rotational speed at a predetermined rotational speed (for example, 2000 rpm) that is most efficient for improving fuel efficiency. However, when the power generation request is large, the engine 10 is operated at an engine speed higher than a predetermined speed corresponding to the power generation request.

  Further, the control unit 100 causes the engine 10 to perform a catalyst regeneration operation when the NOx occlusion amount in the NOx catalyst 82 becomes a predetermined amount or more. Specifically, the control unit 100 estimates the NOx occlusion amount. When the NOx occlusion amount obtained by the estimation becomes a predetermined amount or more, the control unit 100 causes the engine 10 to perform the catalyst regeneration operation. In the catalyst regeneration operation, the engine 10 is operated at a rich air-fuel ratio in which the air-fuel ratio is richer than the stoichiometric air-fuel ratio (for example, the excess air ratio λ = 0.8). By operating the engine 10 at a rich air-fuel ratio, the fuel that has reached the NOx catalyst 82 functions as a reducing agent, and NOx occluded in the NOx catalyst 82 is reduced. The catalyst regeneration operation is continued until the NOx occlusion amount is sufficiently reduced (for example, until the NOx occlusion amount becomes 0). For example, the catalyst regeneration operation may be performed for a predetermined time (for example, 10 seconds) in which the NOx occlusion amount is sufficiently reduced.

  The catalyst regeneration operation is a constant speed operation at the same engine speed as that during the power generation operation. Further, during the catalyst regeneration operation, the motor generator 20 is made idle, and the engine 10 is made idle. The idle operation state is basically a no-load operation state, but may be a light load operation state in which the engine 10 is subjected to a light load equal to or less than a predetermined load (a light load similar to the engine auxiliary machine).

  Hereinafter, the catalyst regeneration operation by the control unit 100 will be described in detail. FIG. 3 is the first half of a flowchart of the catalyst regeneration operation. FIG. 4 is the latter half of the flowchart of the catalyst regeneration operation.

  First, in step S101, the control unit 100 reads output signals from the various sensors.

  In step S102, the control unit 100 reads the NOx occlusion amount from the memory. The control unit 100 calculates the NOx supplement amount supplemented by the NOx catalyst 82 during operation of the engine 10, accumulates the NOx supplement amount, and stores the NOx occlusion amount in the memory.

  Specifically, the NOx supplement amount changes according to the engine operating state including the state of the NOx catalyst 82. The supplemental amount of NOx includes the maximum storage amount that can be stored by the NOx catalyst 82 in the current engine operation state, the NOx storage amount accumulated up to the previous engine operation, and the NOx amount flowing into the NOx catalyst 82 in the current engine operation state. Based on the above.

  The maximum storage amount that can be stored by the NOx catalyst 82 varies depending on the state of the exhaust gas and the state of the NOx catalyst 82. Therefore, the control unit 100 obtains the maximum occlusion amount that can be occluded by the NOx catalyst 82 by comparing the engine speed, the engine load (output), the exhaust gas temperature, the NOx catalyst temperature, and the like with a preset map.

  The NOx occlusion amount accumulated up to the previous engine operation is read from the memory.

  The amount of NOx flowing into the NOx catalyst 82 changes according to the engine speed and the engine load. Therefore, the control unit obtains the NOx amount flowing into the NOx catalyst 82 by comparing the engine speed and the engine load with a preset map.

  The control unit 100 flows into the NOx catalyst 82 in the current engine operation state, the maximum storage amount that can be stored in the NOx catalyst 82, the NOx storage amount accumulated up to the previous engine operation, and the current engine operation state. Based on the NOx amount to be calculated, the NOx supplement amount in the current engine operating state is calculated. Then, the control unit 100 adds the obtained NOx supplement amount to the previous NOx occlusion amount and stores it in the memory as the NOx occlusion amount.

  In step S102, the control unit 100 reads the NOx occlusion amount thus stored in the memory.

  In step S103, the control unit 100 determines whether the power generation operation is being performed. If the power generation operation is not being performed, the control unit 100 returns to step S101. If the power generation operation is being performed, the control unit 100 proceeds to step S104. During the power generation operation, the vehicle is in an operation state with a predetermined load, and the air-fuel ratio at that time is A1 leaner than the stoichiometric air-fuel ratio. The power generation operation is an example of a lean operation in which the air-fuel ratio is leaner than that in the catalyst regeneration operation.

  In step S104, the control unit 100 determines whether or not the NOx occlusion amount has increased to the extent that the regeneration of the NOx catalyst 82 is necessary. Specifically, the control unit 100 determines whether or not the NOx occlusion amount is greater than or equal to a predetermined first occlusion amount. The first storage amount is a value smaller than the maximum storage amount of the NOx catalyst 82 and close to the maximum storage amount, and is a value for determining the necessity of regeneration of the NOx catalyst 82. When the NOx storage amount is greater than or equal to the first storage amount, the control unit 100 proceeds to step S105, while when the NOx storage amount is less than the first storage amount, the control unit 100 proceeds to step S117.

  In step S105, the control unit 100 determines whether or not the SOC of the battery 30 is equal to or greater than a predetermined first capacity (for example, 20%). When the SOC is greater than or equal to the first capacity, the control unit 100 proceeds to step S106, while when the SOC is smaller than the first capacity, the control unit 100 proceeds to step S113.

  In step S106, the control unit 100 determines whether the required power generation amount is equal to or less than a predetermined power generation threshold value. This power generation threshold value is a value that serves as a reference as to whether or not it is necessary to quickly end the catalyst regeneration operation and restart power generation at an early stage. When the required power generation amount is less than or equal to the power generation threshold value, the control unit 100 proceeds to step S107, whereas when the required power generation amount is greater than the power generation threshold value, the control unit 100 proceeds to step S113.

  That is, the NOx occlusion amount reaches an amount that requires regeneration of the NOx catalyst 82 (NOx occlusion amount is greater than or equal to the first occlusion amount), and it is not necessary to charge the battery immediately (SOC is greater than or equal to the first capacity), and a large amount of power generation Is not required (the required power generation amount is equal to or less than the power generation threshold), the control unit 100 proceeds to step S107. As will be described in detail later, a catalyst regeneration operation with NOx suppression shift control is performed after step S107. On the other hand, even if the NOx occlusion amount has reached an amount that requires regeneration of the NOx catalyst 82 (NOx occlusion amount is greater than or equal to the first occlusion amount), is it necessary to charge the battery immediately (SOC is less than the first capacity)? ) Or when a large amount of power generation is required (the required power generation amount is larger than the power generation threshold), the control unit 100 proceeds to step S113. As will be described in detail later, after step S113, a catalyst regeneration operation with normal transition control is performed.

  When the NOx occlusion amount is less than the first occlusion amount in step S104, the control unit 100 determines in step S117 whether the NOx occlusion amount is greater than or equal to a predetermined second occlusion amount. The second occlusion amount is a value smaller than the first occlusion amount, for example, 90% of the first occlusion amount. When the NOx storage amount is greater than or equal to the second storage amount, the control unit 100 proceeds to step S118, while when the NOx storage amount is less than the second storage amount, the control unit 100 returns to step S101.

  In step S118, the control unit 100 determines whether or not the SOC of the battery is equal to or less than a predetermined second capacity. The second capacity is a value larger than the first capacity, for example, 30%. When the SOC is less than or equal to the second capacity, the control unit 100 proceeds to step S107, while when the SOC is greater than the second capacity, the control unit 100 returns to step S101.

  In other words, even if it is determined in step S104 that the NOx occlusion amount has not increased to the extent that regeneration of the NOx catalyst 82 is necessary, the process does not always return to step S101, and the NOx occlusion amount is immediately increased. When the amount of regeneration 82 reaches a necessary amount (NOx occlusion amount is greater than or equal to the second occlusion amount) and the battery immediately needs to be quickly charged (SOC is less than or equal to the second capacity). Does not return to step S101, but proceeds to step S107. In such a state, there is a possibility that the NOx occlusion amount may reach an amount that requires regeneration of the NOx catalyst 82 in a state where the SOC is lowered. Therefore, the catalyst regeneration operation with NOx suppression shift control is performed in advance.

  In step S107, the control unit 100 stops the power generation by the engine 10. That is, the control unit 100 puts the motor generator 20 in the idling state and stops driving the motor generator 20 by the engine 10.

  In subsequent step S108, the control unit 100 performs a catalyst regeneration operation with NOx suppression shift control. The NOx suppression shift control is to reduce the NOx emission amount from the combustion chamber at the time of operation shift. FIG. 5 is a time chart of the catalyst regeneration operation with NOx suppression shift control, where (A) shows the excess air ratio, (B) shows the fuel injection timing, and (C) shows the ignition timing.

  As shown in FIG. 5A, the control unit 100 changes the air-fuel ratio of the engine 10 from A1 in the power generation operation (for example, excess air ratio = 2.3) to A2 in the catalyst regeneration operation (for example, excess air ratio = 0). 8), the opening of the throttle valve 16 and the fuel injection amount are gradually changed. A1 is an air-fuel ratio leaner than the stoichiometric air-fuel ratio, and A2 is an air-fuel ratio richer than the stoichiometric air-fuel ratio.

  Specifically, the control unit 100 gradually changes the target air-fuel ratio from the air-fuel ratio A1 corresponding to the power generation operation to the air-fuel ratio A2 corresponding to the catalyst regeneration operation, while the actual air-fuel ratio detected by the air-fuel ratio sensor 105 is the target air-fuel ratio. The opening degree of the throttle valve 16 and the fuel injection amount are feedback-controlled so that the fuel ratio becomes the same.

  At this time, as shown in FIG. 5B, the control unit 100 generates fuel injection timing while the air-fuel ratio of the engine 10 is changing from the air-fuel ratio A1 in the power generation operation to the air-fuel ratio A2 in the catalyst regeneration operation. It is advanced more than during operation and during catalyst regeneration operation. Thereby, the time in which air and fuel are mixed in the cylinder can be lengthened, and the air-fuel mixture can be made homogeneous.

  Further, the control unit 100 adjusts the advance amount of the fuel injection timing according to the target air-fuel ratio. Specifically, the advance amount of the fuel injection timing is increased as the air-fuel ratio becomes richer. As the air-fuel ratio becomes richer, fuel is more likely to be unevenly distributed in the cylinder, so by increasing the advance amount of the fuel injection timing as the air-fuel ratio becomes richer, the air-fuel mixture becomes homogeneous even when the air-fuel ratio becomes richer. can do. In FIG. 5B, the control unit 100 advances the fuel injection timing by a predetermined amount as soon as the change of the air-fuel ratio is started, and then gradually adjusts the advance amount according to the air-fuel ratio. doing.

  As shown in FIG. 5C, the ignition timing in the catalyst regeneration operation is set later than the ignition timing in the power generation operation. For example, the ignition timing in the catalyst regeneration operation is a predetermined timing after the compression top dead center, and the ignition timing in the power generation operation is a predetermined timing before the compression top dead center. As shown in FIG. 5C, the control unit 100 does not change the ignition timing from the ignition timing of the power generation operation to the ignition timing of the catalyst regeneration operation at the time of shifting to the operation, but instead changes the ignition timing to the air-fuel ratio and the fuel injection timing. Is gradually changed in accordance with the amount of advancement. Specifically, the control unit 100 retards as the air-fuel ratio becomes richer and the advance amount of the combustion supply timing increases. In FIG. 5C, only the ignition timing of one spark plug 19 is shown, but the ignition timing of the other spark plug 19 also changes in the same manner.

  By retarding the ignition timing in this way, it is possible to realize an appropriate engine operating state according to the air-fuel ratio and the fuel injection timing, and it is possible to reduce a sudden change in the engine speed when the air-fuel ratio changes.

  In FIG. 5C, the control unit 100 retards the ignition timing by a predetermined amount as soon as the change of the air-fuel ratio is started in accordance with the change mode of the fuel injection timing. In addition, the angle is gradually retarded according to the advance amount of the fuel injection timing.

  In the above description, the control unit 100 feedback-controls the air-fuel ratio based on the detection result of the air-fuel ratio sensor 105 at the time of operation transition, but is not limited to this. For example, the control unit 100 changes the opening and the fuel injection amount of the throttle valve 16 from the opening and the fuel injection amount corresponding to the operation before the transition to the opening and the fuel injection amount corresponding to the operation after the transition at the time of the operation transition. Instead of changing at a stretch, the advance amount of the combustion injection timing may be adjusted according to the gradually changing air-fuel ratio.

  When the air-fuel ratio becomes A2, the control unit 100 starts the catalyst regeneration operation. In the catalyst regeneration operation, the control unit 100 retards the fuel injection timing to the fuel injection timing corresponding to the catalyst regeneration operation. In the example of FIG. 5B, the fuel injection timing corresponding to the catalyst regeneration operation is the same as the fuel injection timing corresponding to the power generation operation.

  Note that, during the catalyst regeneration operation, the fuel injection timing is retarded compared to when the operation is shifted, so the degree of homogeneity of the air-fuel mixture decreases. However, even if unburned fuel is generated due to the uneven distribution of fuel, since the fuel is used for regeneration of the NOx catalyst 82, regeneration of the NOx catalyst 82 can be promoted.

  Thereafter, in step S109, the control unit 100 executes the catalyst regeneration operation for a predetermined execution time. This execution time is a time sufficient for the first storage amount of NOx to be reduced, and is obtained in advance by experiments or the like. Then, when the execution time has elapsed, the control unit 100 proceeds to step S110 to end the catalyst regeneration operation.

  In step S110, the control unit 100 performs the same NOx suppression transition control as when transitioning to the catalyst regeneration operation. Specifically, as shown in FIG. 5A, the control unit 100 sets the opening degree of the throttle valve 16 and the fuel injection amount so that the air-fuel ratio of the engine 10 changes from A2 in the catalyst regeneration operation to A1 in the power generation operation. Change gradually. At this time, as shown in FIG. 5B, the control unit 100 generates fuel injection timing while the air-fuel ratio of the engine 10 is changing from the air-fuel ratio A2 in the catalyst regeneration operation to the air-fuel ratio A1 in the power generation operation. It is advanced more than during operation and during catalyst regeneration operation. The advance amount of the fuel injection timing is adjusted according to the air-fuel ratio so that it becomes smaller as the air-fuel ratio becomes leaner. In addition, as shown in FIG. 5C, the control unit 100 generates ignition timing while the air-fuel ratio of the engine 10 is changing from the air-fuel ratio A2 in the catalyst regeneration operation to the air-fuel ratio A1 in the power generation operation. From the ignition timing of the operation to the ignition timing of the catalyst regeneration operation, the angle is gradually advanced according to the advance amount of the air-fuel ratio and the fuel injection timing.

  When the air-fuel ratio becomes A1, the control unit 100 restarts the power generation operation.

  In subsequent step S111, the control unit 100 resets the NOx occlusion amount.

  On the other hand, when the process proceeds from step S105, S106 to step S113, the control unit 100 stops the power generation by the engine 10. That is, the control unit 100 puts the motor generator 20 in the idling state and stops driving the motor generator 20 by the engine 10.

  In subsequent step S114, the control unit 100 performs a catalyst regeneration operation with normal transition control. The normal transition control shortens the transition period compared to the NOx suppression transition control. FIG. 6 is a time chart of the catalyst regeneration operation with normal transition control, where (A) shows the excess air ratio, (B) shows the fuel injection timing, and (C) shows the ignition timing.

  As shown in FIG. 6A, the control unit 100 determines the fuel injection amount and the opening degree of the throttle valve 16 from the fuel injection amount and the opening degree corresponding to the air-fuel ratio A1 in the power generation operation and the air-fuel ratio A2 in the catalyst regeneration operation. The fuel injection amount and the opening degree corresponding to are changed at once. Since there is a response delay of each actuator, the fuel injection amount and the opening of the throttle valve 16 change with a slight response delay. In addition to this response delay, there is also a fuel and air response delay, so the air-fuel ratio does not change instantaneously from A1 to A2, but changes with some response delay. However, the period during which the air-fuel ratio changes from A1 to A2 is shorter than the NOx suppression transition control.

  At this time, as shown in FIG. 6B, the control unit 100 changes the fuel injection timing at once from the fuel injection timing corresponding to the power generation operation to the fuel injection timing corresponding to the catalyst regeneration operation. In the example of FIG. 6B, the fuel injection timing corresponding to the power generation operation matches the fuel injection timing corresponding to the catalyst regeneration operation. Therefore, the control unit 100 maintains the fuel injection timing constant at the time of operation shift.

  Further, as shown in FIG. 6C, the control unit 100 changes the ignition timing at a stretch from the ignition timing corresponding to the power generation operation to the ignition timing corresponding to the catalyst regeneration operation.

  As described above, in the normal transition control, since the power generation operation is switched to the catalyst regeneration operation at once, the operation transition period from the power generation operation to the catalyst regeneration operation is shortened.

  Thereafter, in step S115, the control unit 100 executes the catalyst regeneration operation for a predetermined execution time. This execution time is a time sufficient for the first storage amount of NOx to be reduced, and is obtained in advance by experiments or the like. When the execution time has elapsed, the control unit 100 proceeds to step S116 to end the catalyst regeneration operation.

  In step S116, the control unit 100 performs normal transition control similar to that when transitioning to the catalyst regeneration operation. Specifically, as shown in FIG. 6 (A), the control unit 100 sets the fuel injection amount and the opening degree of the throttle valve 16 to the fuel injection amount corresponding to the air-fuel ratio A2 in the catalyst regeneration operation and the opening degree. The air-fuel ratio of the engine 10 is changed from A2 to A1 at a stroke by changing the fuel injection amount and the opening corresponding to the air-fuel ratio A1 of the power generation operation at a stroke. Further, as shown in FIG. 6B, the control unit 100 maintains the fuel injection timing constant. Furthermore, as shown in FIG. 6C, the control unit 100 changes the ignition timing at a stretch from the ignition timing corresponding to the catalyst regeneration operation to the ignition timing corresponding to the power generation operation.

  When the air-fuel ratio becomes A1, the control unit 100 restarts the power generation operation.

  Thereafter, the control unit 100 proceeds to step S111 and resets the NOx occlusion amount.

  Therefore, the hybrid vehicle 1 includes an engine 10, a motor generator 20 that is driven by the engine 10 to generate power, a three-way catalyst 81 and a NOx storage reduction catalyst 82 that are provided in the exhaust system of the engine 10, and the engine 10. And the control unit 100 for controlling the motor generator 20, and the control unit 100 is stored in the NOx storage reduction catalyst 82 by operating the engine 10 in a state where the air-fuel ratio of the engine 10 is rich. The catalyst regeneration operation is performed to reduce the NOx and regenerate the NOx occlusion reduction catalyst 82, and the engine 10 is operated in a state where the air-fuel ratio of the engine 10 is leaner than that during the catalyst regeneration operation. At the time of operation transition from the lean operation to the catalyst regeneration operation, Changes the air-fuel ratio of the engine 10 from the air-fuel ratio corresponding to the operation before the transition to the air-fuel ratio corresponding to the operation after the transition at the time of the operation transition from the catalyst regeneration operation to the lean operation. While the air-fuel ratio of the engine is changing, NOx suppression transition control is executed to advance the fuel injection timing to the engine 10 more than during the operation before the transition and during the operation after the transition.

  According to the above configuration, at the time of the operation transition, while the air-fuel ratio of the engine 10 is changing, the fuel injection timing to the engine 10 is advanced than during the operation before the transition and during the operation after the transition. When the fuel injection timing is advanced, the time during which the fuel is mixed with air becomes longer, so that the degree of homogeneity of the air-fuel mixture increases. Thereby, uneven distribution of fuel is reduced, and the amount of NOx generated is reduced. As a result, an increase in the NOx emission amount when the NOx storage reduction catalyst 82 is regenerated can be suppressed.

  Further, the control unit 100 increases the advance amount of the fuel injection timing at the time of the operation transition as the air-fuel ratio of the engine 10 becomes richer.

  According to this configuration, the air-fuel mixture can be homogenized even when the air-fuel ratio becomes rich. That is, when the air-fuel ratio becomes rich, fuel becomes more unevenly distributed. However, even if the air-fuel ratio becomes rich, the advance amount of the fuel injection timing increases, and the time for which the fuel and air are mixed becomes longer. As a result, the air-fuel mixture can be homogenized and the NOx emission amount can be reduced.

  Further, the control unit 100 retards the ignition timing of the engine 10 according to the air-fuel ratio of the engine 10 and the advance amount of the fuel injection timing when the operation is shifted.

  According to this configuration, since the ignition timing is adjusted according to the advance amount of the air-fuel ratio and the fuel injection timing, it is possible to realize an appropriate engine operating state according to the air-fuel ratio and the fuel injection timing and to change the air-fuel ratio. It is possible to reduce a sudden change in the engine speed when the engine is operated.

  Further, in the NOx suppression control, the control unit 100 operates the engine 10 so that the air-fuel ratio of the engine 10 changes from the air-fuel ratio corresponding to the operation before the transition to the air-fuel ratio corresponding to the operation after the transition. The state is gradually changed, and the advance amount of the fuel injection timing is adjusted according to the air-fuel ratio of the engine 10, and the SOC of the battery 30 is not less than a predetermined first capacity and the required power generation amount Is not greater than a predetermined power generation threshold value, the NOx suppression shift control is executed. On the other hand, when the SOC of the battery 30 is smaller than the first capacity or the required power generation amount is larger than the power generation threshold value, The air-fuel ratio of the engine 10 is changed from the air-fuel ratio corresponding to the operation before the transition to the air-fuel ratio corresponding to the operation after the transition in a shorter period than the NOx suppression transition control. Performing a normal transition control for changing the operating state of the engine 10 so that reduction.

  According to the above configuration, when the SOC of the battery 30 is equal to or greater than the predetermined first capacity and the required power generation amount is equal to or less than the predetermined power generation threshold, that is, the SOC of the battery 30 has a margin and the required power generation amount is not so much. When it is not large, NOx suppression shift control is performed. According to the NOx suppression shift control, the NOx emission amount can be reduced. On the other hand, when the SOC of the battery 30 is smaller than the first capacity or the required power generation amount is larger than the power generation threshold, that is, the SOC of the battery 30 has no margin or the required power generation amount is large and the urgency of power generation is high. Sometimes normal transition control is performed. According to the normal shift control, the shift of operation can be performed at an early stage, so that the time from the end of the catalyst regeneration operation to the restart of the power generation operation can be shortened.

  Further, the control unit 100 executes the catalyst regeneration operation when the NOx occlusion amount of the NOx occlusion reduction catalyst 82 is equal to or greater than a predetermined first occlusion amount, and the NOx occlusion amount of the NOx occlusion reduction catalyst 82 is increased. Even when the storage amount is smaller than the first storage amount, the NOx storage amount is equal to or larger than the second storage amount smaller than the first storage amount and the SOC of the battery 30 is larger than the first capacity. When the capacity is less than or equal to the capacity, the catalyst regeneration operation is executed while performing the NOx suppression transition control.

  According to the above configuration, when the NOx occlusion amount is greater than or equal to the first occlusion amount, the catalyst regeneration operation with NOx suppression shift control is executed. However, even if the NOx storage amount is less than the first storage amount, the NOx storage amount is not less than the second storage amount (<first storage amount) and the SOC of the battery 30 is not more than the second capacity (> first capacity). In some cases, a catalyst regeneration operation is performed. That is, when the NOx occlusion amount is equal to or greater than the second occlusion amount and the SOC of the battery 30 is equal to or less than the second capacity, the NOx occlusion amount may soon reach the first occlusion amount. The SOC may be lower than the first capacity. In this case, since it is necessary to execute charging at an early stage, the normal transition control is executed as described above. However, from the viewpoint of NOx emission amount, NOx suppression shift control is more preferable than normal shift control. Therefore, when the NOx occlusion amount is equal to or greater than the second occlusion amount and the SOC of the battery 30 is equal to or less than the second capacity, the catalyst regeneration operation with NOx suppression shift control is executed in advance. Thereby, the catalyst regeneration operation in which the NOx emission amount is suppressed becomes possible.

<< Other Embodiments >>
As described above, the embodiment has been described as an example of the technique disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can also be applied to an embodiment in which changes, replacements, additions, omissions, and the like are appropriately performed. Moreover, it is also possible to combine each component demonstrated by the said embodiment and it can also be set as a new embodiment. In addition, among the components described in the attached drawings and the detailed description, not only the components essential for solving the problem, but also the components not essential for solving the problem in order to illustrate the technology. May also be included. Therefore, it should not be immediately recognized that these non-essential components are essential as those non-essential components are described in the accompanying drawings and detailed description.

  About the said embodiment, it is good also as following structures.

  In the said embodiment, although the engine 10 is a rotary piston engine, it is not restricted to this. The engine 10 may be a reciprocating engine. The fuel is not limited to hydrogen, and may be gasoline or light oil.

  The control by the control unit 100 is not limited to the control of the flowchart. As long as the fuel injection timing is advanced from the lean operation and the catalyst regeneration operation during the transition between the lean operation and the catalyst regeneration operation, the steps may be omitted or the order of the steps may be changed. For example, regardless of the SOC of the battery 30 or the required power generation amount, if the NOx occlusion amount is equal to or higher than the first threshold value, the catalyst regeneration operation with NOx suppression shift control may be performed.

  In FIG. 5B, the fuel injection timing is advanced by a predetermined amount as soon as the air-fuel ratio change is started, and then gradually advanced according to the air-fuel ratio. It is not limited to. The fuel injection timing may be gradually advanced from the air-fuel ratio of the power generation operation without being advanced at a stretch. Similarly, the ignition timing is not limited to a mode in which the ignition timing is retarded by a predetermined amount as soon as the change of the air-fuel ratio is started, and then gradually retarded according to the air-fuel ratio, but gradually from the ignition timing of the power generation operation. You may make it retard.

  Alternatively, the advance amount of the fuel injection timing during the operation transition changes according to the air-fuel ratio, but may be maintained constant. Similarly, the ignition timing during the operation transition may not be changed according to the air-fuel ratio and may be kept constant. In that case, the ignition timing may be set to any of ignition timing of power generation operation, ignition timing of catalyst regeneration operation, and ignition timing other than power generation operation and catalyst regeneration operation.

  In the above-described embodiment, the power generation operation is described as an example of the lean operation in which the air-fuel ratio is leaner than that of the catalyst regeneration operation. However, the lean operation is not limited to the power generation operation. If the air-fuel ratio is leaner than the catalyst regeneration operation, any operation state can be the lean operation.

  As described above, the technology disclosed herein is useful for a hybrid vehicle including a NOx storage reduction catalyst.

DESCRIPTION OF SYMBOLS 1 Hybrid vehicle 10 Engine 20 Motor generator 30 Battery 81 Three-way catalyst 82 NOx storage reduction catalyst 100 Control unit (control part)

Claims (5)

Engine,
A motor generator driven by the engine to generate electricity;
A three-way catalyst and a NOx storage reduction catalyst provided in the exhaust system of the engine;
A control unit for controlling the engine and the motor generator;
The controller is
By operating the engine in a state where the air-fuel ratio of the engine is rich, the catalyst regeneration operation is performed to reduce the NOx stored in the NOx storage reduction catalyst and regenerate the NOx storage reduction catalyst. And
At the time of operation transition from the lean operation in which the engine is operated in a leaner state than the catalyst regeneration operation to the catalyst regeneration operation, or from the catalyst regeneration operation to the lean operation At the time of the operation transition, the air-fuel ratio of the engine is changed from the air-fuel ratio corresponding to the operation before the transition to the air-fuel ratio corresponding to the operation after the transition, and while the air-fuel ratio of the engine is changing, A hybrid vehicle that executes NOx suppression transition control that advances the fuel injection timing more than during driving before transition and during driving after transition. The hybrid vehicle according to claim 1,
The control unit is a hybrid vehicle that increases an advance amount of the fuel injection timing at the time of the operation transition as the air-fuel ratio of the engine becomes richer. The hybrid vehicle according to claim 2,
The control unit is a hybrid vehicle that retards the ignition timing of the engine according to the air-fuel ratio of the engine and the advance amount of the fuel injection timing when the operation is shifted. The hybrid vehicle according to any one of claims 1 to 3,
The controller is
In the NOx suppression control, the engine operating state is gradually changed so that the air-fuel ratio of the engine changes from the air-fuel ratio corresponding to the operation before the transition to the air-fuel ratio corresponding to the operation after the transition. It is configured to adjust the advance amount of the fuel injection timing according to the fuel ratio,
When the SOC of the battery is equal to or greater than a predetermined first capacity and the required power generation amount is equal to or less than a predetermined power generation threshold, the NOx suppression transition control is executed,
When the SOC of the battery is smaller than the first capacity or the required power generation amount is larger than the power generation threshold, the air-fuel ratio of the engine after the transition from the air-fuel ratio corresponding to the operation before the transition is changed at the time of the operation transition. A hybrid vehicle that performs normal transition control that changes the operating state of the engine so that the air-fuel ratio corresponding to driving changes in a shorter period than the NOx suppression transition control. In the hybrid vehicle according to claim 4,
The controller is
Performing the catalyst regeneration operation when the NOx occlusion amount of the NOx occlusion reduction catalyst is equal to or greater than a predetermined first occlusion amount;
Even when the NOx occlusion amount of the NOx occlusion reduction catalyst is smaller than the first occlusion amount, the NOx occlusion amount is not less than the second occlusion amount smaller than the first occlusion amount and the SOC of the battery. A hybrid vehicle that performs the catalyst regeneration operation while performing the NOx suppression transition control when the engine is less than or equal to a second capacity that is greater than the first capacity.

Images