JP2017048727A - Engine control device of series hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the deterioration of fuel economy as much as possible while avoiding that incongruity caused by a rise of an engine sound imparted to an occupant of a series hybrid vehicle 1 at a high-engine output requirement.SOLUTION: At a high-engine output requirement, when an engine output at a high-engine output requirement can be obtained by setting a rise amount of an engine rotation number with respect to a prescribed rotation number to a set rotation number or smaller, a first operation is performed for raising the engine rotation number to a rotation number at which the engine output at the high-engine output requirement can be obtained, and on the other hand, when the engine output at the high-engine output requirement cannot be obtained if the rise amount is not set larger than the set rotation number, a second operation is performed for raising a supply ratio of first fuel in which a power generation amount per unit volume is large with respect to second fuel while operating an engine 10 at the set rotation number, and setting a combustion air-fuel ratio in a combustion chamber of the engine 10 to a stoichiometric air-fuel ratio.SELECTED DRAWING: Figure 1

Description

  The present invention belongs to a technical field related to an engine control device of a series hybrid vehicle.

  Conventionally, an engine, a generator driven by the engine to generate electric power, a battery for charging electric power generated by the generator, and at least one of electric power discharged from the battery and electric power generated by the generator A series hybrid vehicle having a drive motor for driving a vehicle is known (for example, see Patent Document 1). This series hybrid vehicle usually has a battery running mode in which the vehicle is driven by the discharged electric power of the battery and a charging running mode in which the vehicle is driven while the engine is operated and the battery is charged through the generator by the output of the engine. When the remaining capacity (SOC) of the battery is lowered and switched to the charging travel mode, the engine is operated to generate power by the generator, and the generated power is supplied to the battery and also to the drive motor. The In Patent Document 1, the engine is operated at a predetermined rotational speed (in Patent Document 1, the rotational speed is in the range of 1800 rpm to 2200 rpm).

  As the engine, a multi-fuel engine using a first fuel and a second fuel is known. For example, in Patent Document 2, hydrogen and methane are mixed and used.

JP, 2014-210457, A JP 2004-190640 A

  In the above series hybrid vehicle, it is usually preferable that the engine is normally operated at a predetermined rotational speed as in Patent Document 1. That is, the fuel efficiency can be improved by setting the predetermined rotational speed to a rotational speed at which the engine efficiency is equal to or higher than a predetermined value.

  Further, when the engine of the series hybrid vehicle is a multi-fuel engine using the first fuel and the second fuel, the first and second fuels are supplied to the engine at a predetermined ratio during the steady operation. . Furthermore, in order to improve emissions, it is preferable that the combustion air-fuel ratio in the combustion chamber of the engine be a predetermined lean air-fuel ratio during the steady operation.

  By the way, for example, when the battery travel mode is switched to the charge travel mode, particularly when the remaining capacity of the battery is lower than the value to be switched from the battery travel mode to the charge travel mode, It is preferable to make the capacity equal to or higher than this value as early as possible. For this purpose, the charging power of the battery is increased by increasing the engine output higher than that in the steady operation and increasing the power generated by the generator.

  However, if the engine speed is simply increased when the engine output is made higher than that during the steady operation, the vehicle occupant may feel uncomfortable due to an increase in engine noise and the fuel consumption may deteriorate.

  The present invention has been made in view of such a point, and an object of the present invention is to provide an engine to a vehicle occupant at the time of a high engine output request that requires a higher engine output than during steady engine operation. The purpose is to suppress the deterioration of fuel consumption as much as possible while avoiding a sense of incongruity due to an increase in sound.

  In order to achieve the above object, in the present invention, an engine configured to be able to supply the first fuel and the second fuel, a generator driven by the engine to generate electric power, and electric power generated by the generator An engine control device for a series hybrid vehicle having a battery for charging the vehicle and a drive motor for driving the vehicle driven by at least one of the electric power discharged from the battery and the electric power generated by the generator The first fuel is a fuel having a higher calorific value per unit volume than the second fuel, and includes control means for controlling the operation of the engine, and the control means supplies the first and second fuels. An engine that supplies the engine at a predetermined ratio and operates the engine at a predetermined rotational speed while setting the combustion air-fuel ratio in the combustion chamber of the engine to a predetermined lean air-fuel ratio. When a high engine output request is made to request a higher engine output than during steady state operation, the engine speed is increased above the predetermined engine speed with the predetermined ratio and the predetermined lean air-fuel ratio. When the engine output at the time of the high engine output request can be achieved by setting the amount of increase with respect to the predetermined rotational speed to be equal to or less than the preset rotational speed, the predetermined ratio and the predetermined lean air-fuel ratio are set. The first operation of increasing the engine speed to a speed at which the engine output at the time of the high engine output request can be achieved is performed, while the engine speed is the above-mentioned at the predetermined ratio and the predetermined lean air-fuel ratio. The engine output at the time of the high engine output request cannot be achieved unless the amount of increase with respect to the predetermined engine speed is larger than the set engine speed. When the engine is operated at the predetermined speed, the first fuel supply ratio is increased with respect to the predetermined ratio, and the combustion air-fuel ratio in the combustion chamber of the engine is set to the stoichiometric air-fuel ratio. It was set as the structure of performing 2 driving | operations.

  With the above configuration, when the increase amount of the engine speed is equal to or less than the set rotation number, even if the first operation is performed to increase the engine speed, the increase amount is small. It is possible to prevent a sense of incongruity due to an increase in engine sound and to suppress deterioration of fuel consumption as much as possible. On the other hand, at the predetermined ratio and the predetermined lean air-fuel ratio, the engine output at the time of the high engine output request cannot be achieved unless the engine speed increase amount is made larger than the set engine speed. When the engine output at the time of the high engine output request is increased to an achievable rotation speed, the vehicle occupant is given a sense of incongruity due to an increase in engine sound. Therefore, the second operation is performed and the engine is operated at a predetermined rotational speed so as not to give the vehicle occupant an uncomfortable feeling due to an increase in engine sound. However, since the engine output at the time of the high engine output request cannot be achieved in the operation at the predetermined rotation speed, the supply ratio of the first fuel is increased and the combustion air-fuel ratio in the combustion chamber of the engine is set to the stoichiometric air-fuel ratio. The engine output at the time of the high engine output request is achieved. In this case, although the efficiency of the engine is lower than that during steady operation of the engine, the deterioration of fuel consumption can be suppressed as much as possible by operating the engine at a predetermined rotational speed.

  In the engine control apparatus for the series hybrid vehicle, the first fuel is a fuel that has a lower NOx emission amount from the engine and lower ignitability than the second fuel under the same combustion air-fuel ratio. The means is preferably configured to increase the supply ratio of the first fuel as the engine output at the time of the high engine output request is higher when the second operation is executed.

  As a result, even if the engine output at the time of a high engine output request becomes high, the engine output can be achieved while suppressing the NOx emission amount, and the first fuel has low ignitability and combustion is slow. Therefore, the combustion noise can be reduced by increasing the supply ratio of the first fuel.

  As described above, when the second operation is executed, the higher the engine output at the time of the high engine output request, the higher the supply ratio of the first fuel, so that it is provided in the exhaust passage of the engine. And a NOx occlusion reduction catalyst for purifying the exhaust gas of the engine, wherein the NOx occlusion reduction catalyst occludes NOx in the exhaust gas of the engine in a lean air-fuel ratio atmosphere, and stores the occluded NOx in a stoichiometric manner. The control means releases and reduces in an air-fuel ratio atmosphere or a rich air-fuel ratio atmosphere. When the high engine output request is made and the NOx storage reduction catalyst is requested to release the NOx, the control means It is preferable that the second operation is performed regardless of the condition for performing the second operation or the condition for performing the second operation.

  By doing so, it is possible to release and reduce NOx from the NOx occlusion reduction catalyst while executing the second operation.

  Further, when the second operation is performed, the engine for detecting the temperature of the cooling water of the engine when the supply ratio of the first fuel is increased as the engine output at the time of the high engine output request is higher. Water temperature detection means is further provided, and the control means decreases the degree of increase in the supply ratio of the first fuel as the temperature of the cooling water by the engine water temperature detection means is lower during execution of the second operation. It is preferable that it is comprised.

  That is, when the temperature of the cooling water is low and the supply ratio of the first fuel is increased too much, the ignitability is decreased and the combustion stability is lowered, but the degree of increasing the supply ratio of the first fuel is decreased. Thus, combustion stability can be ensured by the second fuel having high ignitability.

  In one embodiment of the engine control apparatus for the series hybrid vehicle, the battery further includes a battery remaining capacity detecting means for detecting a remaining capacity of the battery, and the vehicle travels by a battery traveling mode in which the battery is discharged by the discharged power of the battery, and the engine. And a charging travel mode in which the battery travels while charging the battery via the generator by the output of the engine, and the control means is configured to detect the remaining battery capacity in the battery travel mode. When the remaining capacity of the battery detected by the above is lower than the first predetermined value, the battery is switched to the charging traveling mode, while the remaining capacity of the battery detected by the battery remaining capacity detecting means during the charging traveling mode is Than a second predetermined value set to a value higher than the first predetermined value. A driving mode switching control unit for switching to the battery driving mode, and the high engine output request is made when the battery remaining capacity detecting means is detected in the charging driving mode. The period from when the remaining capacity becomes equal to or lower than the third predetermined value set to a value lower than the first predetermined value until the first predetermined value is reached.

  As a result, the overdischarged battery can be quickly charged, and the remaining capacity of the battery can be quickly returned to the preferred use range. Here, the vehicle occupant can understand that when the engine is operated, the vehicle is switched to the charge travel mode, but when the engine noise becomes high due to the execution of the second operation during the above, the reason cannot be understood, It is easy to cause a sense of incongruity. However, since the engine speed is the same as that in the steady engine operation by executing the second operation, the engine sound does not cause a sense of incongruity to the occupant.

  As described above, according to the engine control apparatus for a series hybrid vehicle of the present invention, the first and second fuels are supplied to the engine at a predetermined ratio, and the combustion air-fuel ratio in the combustion chamber of the engine is set to a predetermined lean air. When the engine output is required to be higher than that during steady engine operation where the engine is operated at a predetermined speed while maintaining the fuel ratio, the engine speed is increased with the predetermined ratio and the predetermined lean air-fuel ratio. When the engine output at the time of the high engine output request can be achieved by raising the number above the predetermined rotational speed and making the amount of increase with respect to the predetermined rotational speed not more than a preset rotational speed, With the predetermined ratio and the predetermined lean air-fuel ratio, the engine speed can be achieved at the engine output when the high engine output is requested. On the other hand, when the first operation for increasing the engine speed to the predetermined speed and the predetermined lean air-fuel ratio is performed, an increase amount of the engine speed with respect to the predetermined speed must be set larger than the set speed. When the engine output at the time of the high engine output request cannot be achieved, the first fuel (per unit volume with respect to the second fuel) with respect to the predetermined ratio while operating the engine at the predetermined rotation speed. When the high engine output request is made, the second operation is performed to increase the supply ratio of the fuel having a high calorific value) and to change the combustion air-fuel ratio in the combustion chamber of the engine to the stoichiometric air-fuel ratio. Deterioration of fuel consumption can be suppressed as much as possible while preventing the passenger from feeling uncomfortable due to an increase in engine sound.

1 is a schematic view of a series hybrid vehicle equipped with an engine control apparatus according to an embodiment of the present invention. It is a block diagram which shows the structure of the engine of the said series hybrid vehicle, and its control system. It is a graph which shows the relationship between the excess air ratio (lambda) and NOx discharge | emission amount from an engine when making it burn with an engine about hydrogen gas, natural gas, and these mixed gas A, B, and C. FIG. It is a graph which shows the relationship between the excess air ratio (lambda) and the HC discharge | emission amount from an engine when making it burn with an engine about hydrogen gas, natural gas, and these mixed gas A, B, and C. FIG. Regarding hydrogen gas, natural gas, and mixed gas A, B, and C thereof, the relationship between the excess air ratio λ and the engine output torque and the excess air ratio λ and the thermal efficiency of the engine when the engine is burned It is a graph which shows a relationship. It is a graph which shows the relationship between the engine output and engine water temperature at the time of execution of a 2nd driving | operation, and the supply ratio of a natural gas. It is a flowchart which shows the processing operation | movement started by the control unit when the ignition switch turns ON. It is a flowchart which shows a part of processing operation for controlling an engine by a control unit. It is a flowchart which shows the remainder of the said processing operation for controlling an engine by a control unit.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram of a series hybrid vehicle 1 (hereinafter simply referred to as a vehicle 1) equipped with an engine control apparatus according to an embodiment of the present invention. The vehicle 1 includes an engine 10, a generator 20 that is driven by the engine 10 to generate electric power, a high-voltage / large-capacity battery 30 that stores (charges) electric power generated by the generator 20, an engine And a drive motor 40 that is driven by at least one of the generated power of the generator 20 that is driven by the power generator 10 and the stored power (discharge power) of the battery 30. In the present embodiment, the generator 20 is a motor generator having a function of a motor, and the engine 10 is driven (cranked) by the generator 20 as a motor to start the engine 10. .

  A first inverter 50 is provided between the generator 20 and the battery 30, and a second inverter 51 is provided between the battery 30 and the drive motor 40. The first inverter 50 and the second inverter 51 are connected to each other, and the battery 30 is connected to the connection line. The power generated by the generator 20 is supplied to the battery 30 via the first inverter 50 and also supplied to the drive motor 40 via the first and second inverters 50 and 51. Discharged power from the battery 30 is supplied to the drive motor 40 via the second inverter 51.

  The output of the drive motor 40 is transmitted to the drive wheels 61 (the left and right front wheels steered by the steering wheel 62) via the differential device 60, whereby the vehicle 1 travels.

  The drive motor 40 is capable of generating regenerative power and operates as a generator when the vehicle 1 is decelerated, and the generated power (regenerative power) is charged in the battery 30. In the charging travel mode described later, the engine 10 is started and the battery 30 is charged with the generated power of the generator 20. The battery 30 can be externally charged by a power source external to the vehicle 1.

  The engine 10 is a power generation engine used to drive the generator 20 to generate power. The engine 10 is a multi-fuel engine configured such that hydrogen gas stored in the hydrogen tank 70 and natural gas (CNG) stored in the CNG tank 71 can be supplied as fuels. Natural gas corresponds to the first fuel, and hydrogen gas corresponds to the second fuel. Natural gas is a fuel having a higher calorific value per unit volume than hydrogen gas. Such a first fuel is not limited to natural gas, and may be propane or butane, for example. Natural gas is a fuel that emits less NOx from the engine 10 (combustion chamber) and has lower ignitability than hydrogen gas under the same combustion air-fuel ratio (the same applies to propane and butane). The second fuel is preferably a highly ignitable fuel such as hydrogen gas.

  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 the 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 (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.

  An intake passage 14 is connected to each of the rotor accommodating chambers 11a so as to communicate with an intake opening that opens to the working chamber in the intake stroke, and communicates with an exhaust opening that opens to the working chamber in the exhaust stroke. An exhaust passage 15 is connected to the front. 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. The cross-sectional area (valve opening degree) of the intake passage 14 is adjusted by being driven by a throttle valve actuator 90 such as a stepping motor on the upstream side of the branch portion of the intake passage 14 (downstream side of an intercooler 86 described later). A throttle valve 16 is provided. The throttle valve 16 adjusts the amount of intake air into each rotor accommodating chamber 11a (the working chamber in the intake stroke). In the engine control described later in this embodiment (except during idle operation), the throttle valve 16 is fully opened.

  Hydrogen ports from which hydrogen gas from the hydrogen tank 70 and natural gas from the CNG tank 71 are respectively injected into the intake passage 14 in each branch passage downstream of the branch portion of the intake passage 14. An injection valve 17A and a CNG port injection valve 17B are provided. The hydrogen gas and natural gas injected by the hydrogen and CNG port injection valves 17A and 17B, respectively, are mixed with air and supplied to the working chamber in the intake stroke. The hydrogen and CNG port injection valves 17A and 17B are used when the engine 10 is extremely cold (when the engine coolant temperature is very low even when the engine is cold and is lower than a preset set temperature). Is a fuel injection valve that is used only at the time of start-up. Basically, fuel (hydrogen gas and natural gas) is directly injected into the combustion chamber from hydrogen and CNG direct injection valves 18A and 18B described later. . In other words, when the engine 10 is extremely cold, the fuel injection openings of the hydrogen and CNG direct injection valves 18A and 18B may be blocked by freezing of water generated by fuel combustion. Therefore, fuel is injected from the hydrogen and CNG port injection valves 17A and 17B exceptionally at the time of start-up during extremely cold. It is possible to eliminate the port injection valves 17A and 17B for hydrogen and CNG. In the following description, it is assumed that fuel (hydrogen gas and natural gas) is injected from the hydrogen and CNG direct injection valves 18A and 18B.

  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 low temperature active three-way catalyst 81 and a NOx occlusion reduction catalyst 82 for purifying exhaust gas are disposed downstream of the merging portion of the exhaust passage 15. The low temperature active three-way catalyst 81 is a three-way catalyst having a catalyst activation temperature lower than that of the NOx storage reduction catalyst 82, and is disposed upstream of the NOx storage reduction catalyst 82. In FIG. 2, arrows shown in the intake passage 14 and the exhaust passage 15 indicate the flow of intake and exhaust.

  The NOx occlusion reduction catalyst 82 is configured, for example, by supporting a NOx occlusion agent such as barium (Ba) or potassium (K) on a carrier containing a noble metal such as platinum (Pt) or palladium (Pd). The NOx in the exhaust gas of the engine 10 is occluded in a lean air-fuel ratio atmosphere, and the occluded NOx is released in a stoichiometric air-fuel ratio atmosphere or a rich air-fuel ratio atmosphere, and the NOx is exhausted in the exhaust gas. It has the function of reducing by reacting with HC and CO.

  In each rotor housing 11 (each cylinder), a hydrogen direct injection valve 18A for directly injecting hydrogen gas from the hydrogen tank 70 into the working chamber (combustion chamber) in the compression stroke of the rotor accommodating chamber 11a; A CNG direct injection valve 18B for directly injecting natural gas from the CNG tank 71 into the working chamber (combustion chamber) in the compression stroke of the rotor accommodating chamber 11a is provided. In each rotor housing 11, two CNG direct injection valves 18B are provided, and these two CNG direct injection valves 18B are arranged in the width direction of the rotor 12 (the direction in which the eccentric shaft 13 extends). (In FIG. 2, the CNG direct injection valve 18B on the back side of the drawing is not visible). In each rotor housing 11, the number of hydrogen direct injection valves 18A, the hydrogen port injection valves 17A, and the CNG port injection valves 17B are all one. In this embodiment, natural gas is always injected from the two CNG direct injection valves 18B.

  Each rotor housing 11 is provided with two spark plugs 19 for igniting hydrogen gas and natural gas respectively injected from hydrogen and CNG direct injection valves 18A and 18B. These spark plugs 19 are ignited in the order of the leading side and the trailing side in the vicinity of the compression top (TDC), and ignite the air-fuel mixture in the working chamber in the compression or expansion stroke.

  The engine 10 is provided with an exhaust turbocharger 85 that supercharges intake air into the working chamber (combustion chamber) in the intake stroke in each rotor accommodating chamber 11a of the engine 10. The exhaust turbocharger 85 includes a compressor 85a disposed upstream of the throttle valve 16 in the intake passage 14 and a downstream side of the merging portion in the exhaust passage 15 and upstream of the three-way catalyst 81. And a turbine 85b disposed in the turbine. The turbine 85b is rotated by the exhaust gas flow, and the rotation of the turbine 85b activates the compressor 85a connected to the turbine 85b to compress the air taken into the intake passage 14. The compressed air is cooled by an intercooler 86 disposed downstream of the compressor 85a and upstream of the throttle valve 16 in the intake passage 14, and then accommodated in each rotor via each branch passage. Inhaled into the working chamber in the intake stroke of the chamber 11a. The NOx occlusion reduction catalyst 82 is disposed on the downstream side of the turbine 85b in the exhaust passage 15.

  The vehicle 1 includes a battery current / voltage sensor 101 that detects a current flowing in 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 an occupant of the vehicle 1 (accelerator opening by an occupant's operation). An opening sensor 102, a vehicle speed sensor 103 that detects the vehicle speed of the vehicle 1, a rotation angle sensor 104 that is provided on the eccentric shaft 13 and detects the rotation angle position of the eccentric shaft 13, and a low-temperature active three-way catalyst in the exhaust passage 15 An air-fuel ratio sensor 105 (configured by a linear O2 sensor in this embodiment) that is disposed between the turbine 81 and the turbine 85 b and detects the air-fuel ratio of the exhaust gas of the engine 10, and the rotor housing 11 It faces the formed water jacket (not shown) and flows through the water jacket. Engine water temperature sensor 106 as engine water temperature detecting means for detecting the temperature of the engine cooling water (engine water temperature), the pressure in the hydrogen tank 70 (that is, the remaining amount of hydrogen gas in the hydrogen tank 70), and the pressure in the CNG tank 71 That is, the tank pressure sensor 107 (provided separately for the hydrogen tank 70 and the CNG tank 71) that detects the remaining amount of natural gas in the CNG tank 71, and the intake flow rate drawn into the intake passage 14 The air flow sensor 108 to detect, the battery temperature sensor 109 to detect the temperature of the battery 30, the operation control of the engine 10, the operation control of the first and second inverters 50 and 51 (that is, the operation of the generator 20 and the drive motor 40). And a control unit 100 for performing control. The rotation angle sensor 104 also serves as an engine rotation speed sensor that detects the rotation speed 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 information signals from 109 etc. are input.

  The generator 20 transmits information on the voltage and current generated by the generator 20 to the control unit 100. The control unit 100 inputs the information and generates power generated by the generator 20 from the information. (Power generation amount) is detected.

  The drive motor 40 transmits information on the rotational speed of the drive motor 40 and information on the regenerative power generation voltage and regenerative power generation current generated by the drive motor 40 to the control unit 100, and the control unit 100 transmits the information. The input is used to control the operation of the drive motor 40.

  Then, based on the input signal, the control unit 100 controls the throttle valve actuator 90, the hydrogen port injection valve 17A, the CNG port injection valve 17B, the hydrogen direct injection valve 18A, the CNG direct injection valve 18B, and A control signal is output to the spark plug 19 to control the engine 10, and a control signal is output to the first and second inverters 50 and 51 to control the generator 20 and the drive motor 40. The control unit 100 constitutes control means for controlling the operation of the engine 10.

  The vehicle 1 is driven by the battery 30 in the battery running mode (at this time, the engine 10 is stopped), the engine 10 is operated, and the output of the engine 10 causes the battery to pass through the generator 20. And a charging travel mode in which the vehicle travels while charging 30. In the present embodiment, since the vehicle 1 is a series hybrid vehicle, in the charging travel mode, charging of the battery 30 and driving of the drive motor 40 are performed with power generated by the generator 20 that generates power by the output of the engine 10.

  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. Thus, the battery current / voltage sensor 101 and the control unit 100 constitute a battery remaining capacity detecting means for detecting the remaining capacity of the battery 30.

  When the remaining capacity of the detected battery 30 becomes lower than a first predetermined value (for example, 30%) during the battery travel mode, the control unit 100 switches to the charge travel mode while the charge travel mode. In the mode, when the detected remaining capacity of the battery 30 becomes higher than a second predetermined value (for example, 70%) set to a value higher than the first predetermined value, the mode is switched to the battery running mode. . Thereby, the remaining capacity of the battery 30 can be maintained within a preferable range that is neither too low nor too high. The control unit 100 includes a travel mode switching control unit that switches between the battery travel mode and the charge travel mode.

  Further, the control unit 100 normally performs an engine steady operation in which the engine 10 is operated at a predetermined rotational speed in the charging travel mode. The predetermined rotational speed is an engine rotational speed within a range (for example, 1800 rpm to 2300 rpm) including the highest efficiency point of the engine 10 such that the efficiency of the engine 10 is equal to or higher than a predetermined value, and is 2000 rpm in the present embodiment. Further, the engine load during the steady engine operation is a medium load or a high load larger than a predetermined load (the engine torque during the steady engine operation is a medium torque or a high torque larger than the predetermined torque). Then, the control unit 100 controls the hydrogen and CNG direct injection valves 18A and 18B so that the operation of the engine 10 during the engine steady operation is performed by mixing hydrogen gas and natural gas. In the present embodiment, hydrogen gas and natural gas are injected into the combustion chamber of the engine 10 at substantially the same volume ratio (both are approximately 50%). At this time, the control unit 100 determines the combustion air-fuel ratio in the combustion chamber when NOx emissions from the engine 10 (combustion chamber), for example, burns only natural gas with the lean-limit combustion air-fuel ratio. The direct injection valves 18A and 18B for hydrogen and CNG are controlled so that the lean air-fuel ratio becomes substantially the same as the NOx emission amount.

  When the required output of the drive motor 40 is larger than the engine output (generated power) during the steady operation of the engine, such as when the vehicle 1 is requested to accelerate more than a predetermined amount in the charging travel mode, the shortage is stored in the battery. Complement with 30 discharge power (do not charge).

  Here, FIG. 3 shows the excess air ratio λ and the engine 10 when hydrogen gas, natural gas, and mixed gas A, B, and C thereof are burned by the engine 10 (rotation speed 2000 rpm, throttle valve 16 fully opened). The relationship with the NOx emission amount from (combustion chamber) is shown. The mixed gas A has hydrogen gas and natural gas at substantially the same volume ratio (both are about 50%), and the mixed gas B has a larger volume ratio of hydrogen gas than the mixed gas A, The mixed gas C has a volume ratio of hydrogen gas larger than that of the mixed gas B. FIG. 4 shows the excess air ratio λ and the amount of HC emissions from the engine 10 (combustion chamber) when the above-mentioned gases shown in FIG. 3 are burned by the engine 10 (rotation speed 2000 rpm, throttle valve 16 fully opened). The relationship is shown. Further, FIG. 5 shows the relationship between the excess air ratio λ and the output torque of the engine 10 when the above-mentioned gases shown in FIG. 3 are burned by the engine 10 (rotation speed 2000 rpm, throttle valve 16 fully opened), and air. The relationship between excess ratio (lambda) and the thermal efficiency of the engine 10 is shown. Here, natural gas is injected from the CNG direct injection valve 18B, and hydrogen gas is injected from the hydrogen port injection valve 17A. In this case, compared with the case where hydrogen gas and natural gas are respectively injected from the hydrogen and CNG direct injection valves 18A and 18B, the magnitude of the output torque and the like change, but the tendency of the above relationship does not change greatly.

  From FIG. 3 to FIG. 5, the combustion air-fuel ratio at the lean limit of natural gas (here, the excess air ratio λ) is 1.6, and stable ignition is achieved even if the excess air ratio λ is larger than this. I can't do it. 3 to 5, the excess air ratio λ is only up to 2.7, but the lean excess air excess ratio λ of hydrogen gas is about 3. 3 to 5, the results when the excess air ratio λ of hydrogen gas is lower than 1.8 are omitted.

  From FIG. 3, if the excess air ratio λ is the same, natural gas has a smaller NOx emission than hydrogen gas, and the mixed gas A, B, C has a larger volume ratio of natural gas (hydrogen gas It can be seen that the smaller the volume ratio), the smaller the NOx emissions. That is, when the volume ratio of hydrogen gas in the hydrogen gas or mixed gas is large, the NOx emission amount increases. However, when the volume ratio of hydrogen gas in the hydrogen gas or mixed gas is large, the lean combustion air-fuel ratio becomes high, so the NOx emission can be reduced by increasing the combustion air-fuel ratio in the combustion chamber. .

  In the present embodiment, during the engine steady operation, hydrogen gas and natural gas are injected into the combustion chamber at substantially the same volume ratio (both 50%). At this time, the combustion air-fuel ratio (excess air ratio λ) in the combustion chamber NOx emission amount from the engine 10 is, for example, a lean air-fuel ratio that is substantially the same as the NOx emission amount when only natural gas is burned with its lean-limit combustion air-fuel ratio (λ = 1.6). To do. In this embodiment, the lean air-fuel ratio is obtained at the point Q2 where the line parallel to the horizontal axis passing through the point Q1 of λ = 1.6 on the natural gas line in FIG. The value of λ (that is, λ = 1.9) is obtained.

  Further, as shown in FIG. 4, when the volume ratio of natural gas in the natural gas or mixed gas is large, if the lean air-fuel ratio is too high, the amount of HC emission becomes excessive, and the low-temperature active three-way catalyst 81 appropriately purifies HC. There is a possibility of being unable to fill. If the combustion air-fuel ratio is a stoichiometric air-fuel ratio (λ = 1), even if the fuel is only natural gas, the amount of HC emission will be at a level where there is no problem.

  The control unit 100 supplies hydrogen gas and natural gas to the engine 10 at a predetermined ratio (in this embodiment, both 50%), and sets the combustion air-fuel ratio in the combustion chamber of the engine 10 to a predetermined lean air-fuel ratio (this In the embodiment, a high engine output request is required to make the engine output higher than that in the steady engine operation in which the engine 10 is operated at a predetermined rotation speed (2000 rpm in the present embodiment) while λ = 1.9). Sometimes, the following first operation is performed or the second operation is performed.

  In the present embodiment, the high engine output request is made when the remaining capacity of the battery is equal to or lower than a third predetermined value set to a value lower than the first predetermined value in the charging travel mode. From the time until the first predetermined value is reached. This is because the overdischarged battery 30 is quickly charged, and the remaining capacity of the battery 30 is quickly returned to the preferred use range (30% to 70%).

  In the first operation, with the predetermined ratio and the predetermined lean air-fuel ratio, the engine speed is increased from the predetermined speed and the amount of increase with respect to the predetermined speed is set to a preset set speed. The following is executed when the engine output at the time of the high engine output request can be achieved. The first operation is an operation in which the engine speed is increased to a speed at which the engine output at the time of the high engine output request can be achieved with the predetermined ratio and the predetermined lean air-fuel ratio. The set rotational speed is an amount of increase that gives the occupant of the vehicle 1 an uncomfortable feeling due to an increase in engine sound when the amount of increase in the engine rotational speed with respect to the predetermined rotational speed is greater than the set rotational speed. The increase amount (for example, 500 rpm) is such that the efficiency of the engine 10 at the engine speed after the increase does not decrease much more than the efficiency at the predetermined rotation speed.

  On the other hand, in the second operation, at the predetermined ratio and the predetermined lean air-fuel ratio, when the amount of increase of the engine speed with respect to the predetermined engine speed is not made larger than the set engine speed, the high engine output is requested. It is executed when the engine output cannot be achieved. In the second operation, while the engine 10 is operated at the predetermined speed, the supply ratio of the first fuel is increased with respect to the predetermined ratio, and the combustion air-fuel ratio in the combustion chamber of the engine 10 is reduced to the stoichiometric air. In this operation, the fuel ratio is set to λ = 1.

  In the present embodiment, the control unit 100 increases the supply ratio of natural gas as the engine output at the time of the high engine output request increases as shown in FIG. However, at the time of execution of the second operation, as shown in FIG. 6, the lower the engine water temperature by the engine water temperature sensor 106, the lower the degree of increasing the natural gas supply ratio. That is, if the engine water temperature is low, the low-temperature active three-way catalyst 81 is not activated, and if the supply ratio of natural gas is excessively increased in this state, the HC emission amount increases and the low-temperature active three-way catalyst 81 Therefore, there is a possibility that HC cannot be purified properly. Therefore, the lower the engine water temperature, the lower the degree of increase in the supply ratio of natural gas, so that the low temperature active three-way catalyst 81 can appropriately purify HC.

  In addition, when there is a NOx release request from the NOx occlusion reduction catalyst 82 at the time of the high engine output request, the control unit 100, regardless of the conditions for executing the first operation or the second operation, A second operation is performed. That is, when NOx is released from the NOx occlusion reduction catalyst 82, the engine 10 needs to be operated at a stoichiometric air-fuel ratio or a rich air-fuel ratio. Therefore, NOx from the NOx occlusion reduction catalyst 82 is reduced while performing the second operation. It can be released and reduced. Here, when there is a request for NOx release, the NOx occlusion amount of the NOx occlusion reduction catalyst 82 is greater than a predetermined occlusion amount (an amount slightly smaller than a level at which it can no longer be occluded). . The NOx occlusion amount can be calculated from the operation history of the engine 10, and the control unit 100 integrates the NOx occlusion amount based on the operation state during the operation of the engine 10.

  The control unit 100 operates the engine 10 with only hydrogen gas and with a stoichiometric air-fuel ratio when there is a request for releasing NOx from the NOx storage reduction catalyst 82 during the steady engine operation. NOx is released from the catalyst 82 and reduced. At this time, the engine 10 is set to idle operation.

  In the battery running mode, the engine 10 is basically stopped. However, when the required output of the drive motor 40 exceeds the maximum dischargeable power of the battery 30, the control unit 100 turns off the engine 10. Operating at the predetermined speed (2000 rpm), the predetermined ratio (both 50%) and the predetermined lean air-fuel ratio (λ = 1.9), and the output of the engine 10 to be operated, The required output of the drive motor 40 is satisfied by the discharged power of the battery 30. At this time, the value of the discharge power of the battery 30 is adjusted so that the engine load is always higher than the set load set to a value higher than the predetermined load. (The engine torque is always higher than the set torque set to a value higher than the predetermined torque).

  When there is a request for releasing NOx from the NOx occlusion reduction catalyst 82 during operation of the engine 10 in the battery running mode, the engine 10 is operated at the predetermined speed, only natural gas, and at the stoichiometric air-fuel ratio. Thus, NOx is released from the NOx occlusion reduction catalyst 82 and reduced. Also at this time, the value of the discharge power of the battery 30 is adjusted, and the engine load is always made higher than the set load (engine torque is made higher than the set torque).

  Here, the maximum dischargeable power varies depending on the temperature of the battery 30. The relationship between the temperature of the battery 30 and the maximum dischargeable power is stored as a map in the memory of the control unit 100, and the control unit 100 uses the map to detect the battery detected by the battery temperature sensor 109. The maximum dischargeable power is detected from 30 temperatures.

  Next, the processing operation by the control unit 100 will be described based on the flowcharts of FIGS. 7 is started when an ignition switch (not shown) of the vehicle 1 is turned ON, and the flowcharts of FIGS. 8 and 9 are processing operations for controlling the engine 10. Is started (when a flag F described later becomes 1).

  When the ignition switch is turned on, the flag F is set to 0 and the engine 10 is stopped in step S1. The fact that the flag F is set to 0 means that the battery is in a battery travel mode in which the engine 10 is traveled by the discharged power of the battery 30 with the engine 10 stopped. Therefore, when the ignition switch is turned on, the battery traveling mode in which the engine 10 is stopped is initially set.

  In the next step S2, various input signals from various sensors are read, and in the next step S3, the required output of the drive motor 40 is calculated based on the signals from the accelerator opening sensor 102 and the vehicle speed sensor 103.

  In the next step S4, it is determined whether or not the remaining capacity (SOC) of the battery 30 is lower than the first predetermined value. When the determination in step S4 is YES, the process proceeds to step S5, while when the determination in step S4 is NO, the process proceeds to step S8.

  In step S5, the flag F is set to 1. However, the flag F is maintained at 3 while the flag F is set to 3 as will be described later. The fact that the flag F is set to 1 means that the charging travel mode is set.

  In the next step S6, the engine 10 is operated (that is, the power is generated by the generator 20), and in the next step S7, it is determined whether or not the ignition switch is turned off. When the determination in step S7 is NO, the process returns to step S2. On the other hand, when the determination in step S7 is YES, the processing operation is terminated.

  In step S8 that proceeds when the determination in step S4 is NO, it is determined whether or not the flag F is 0 and the required output of the drive motor 40 is greater than the maximum dischargeable power of the battery 30. When the determination in step S8 is YES, the process proceeds to step S6. When the determination in step S8 is NO, the process proceeds to step S9.

  In step S9, it is determined whether or not the flag F is 1. If the determination in step S9 is NO, the process proceeds to step S7. If the determination in step S9 is YES, the process proceeds to step S10. .

  In step S10, it is determined whether the remaining capacity (SOC) of the battery 30 is higher than the second predetermined value. If the determination in step S10 is NO, the process proceeds to step S7. If the determination in step S10 is YES, the process proceeds to step S11, the flag F is set to 0, and in the next step S12, the engine 10 is processed. Then, the process proceeds to step S7.

  8 and 9 show how the engine 10 is operated when the engine 10 is operated in step S6. This flowchart is executed in parallel with the flowchart of FIG. 7 when the engine 10 is operated.

  In the first step S51, various input signals necessary for controlling the engine 10 (in particular, the engine water temperature from the engine water temperature sensor 106, the remaining capacity of the battery 30 and the NOx occlusion amount) are read.

  In the next step S52, it is determined whether or not the flag F is 1 or 3. When the determination in step S52 is YES, the process proceeds to step S53, while when the determination in step S52 is NO (that is, in the battery running mode, the required output of the drive motor 40 is greater than the maximum dischargeable power of the battery 30). If so, the process proceeds to step S55.

  In step S53, it is determined whether the remaining capacity (SOC) of the battery 30 is lower than the third predetermined value. If the determination in step S53 is NO, the process proceeds to step S58. If the determination in step S53 is YES, the process proceeds to step S54, the flag F is set to 3, and then the process proceeds to step S64. The fact that the flag F is set to 3 means that the high engine output is requested in the charge travel mode.

  In step S55 that proceeds when the determination in step S52 is NO, it is determined whether or not the NOx occlusion amount of the NOx occlusion reduction catalyst 82 is larger than the predetermined occlusion amount. When the determination in step S55 is YES, the process proceeds to step S56, where the engine 10 is operated only with natural gas, the excess air ratio λ in the combustion chamber is set to 1, and the engine speed is set to 2000 rpm. To do. Thereafter, the process proceeds to step S69.

  On the other hand, when the determination in step S55 is NO, the process proceeds to step S57 where the engine 10 is operated with a mixture of hydrogen gas and natural gas (substantially the same volume ratio) and the excess air ratio λ in the combustion chamber is set to 1. 9 and the engine speed is 2000 rpm, and the engine is operated at a high torque. Thereafter, the process proceeds to step S69.

  In step S58 that proceeds when the determination in step S53 is NO, it is determined whether or not the flag F is three. When the determination in step S58 is NO, the process proceeds to step S61. When the determination in step S58 is YES, the process proceeds to step S59.

  In step S59, it is determined whether the remaining capacity (SOC) of the battery 30 is equal to or greater than the first predetermined value. When the determination in step S59 is NO, the process proceeds to step S64. On the other hand, when the determination in step S59 is YES, the process proceeds to step S60, the flag F is set to 1, and then the process proceeds to step S61.

  In step S61, it is determined whether the NOx occlusion amount of the NOx occlusion reduction catalyst 82 is larger than the predetermined occlusion amount. When the determination in step S61 is YES, the process proceeds to step S62, the engine 10 is operated only with hydrogen gas, the excess air ratio λ in the combustion chamber is set to 1, and the idle operation is performed, and then the process proceeds to step S69. .

  On the other hand, when the determination in step S61 is NO, the process proceeds to step S63 where the engine 10 is operated with a mixture of hydrogen gas and natural gas (substantially the same volume ratio), and the excess air ratio λ in the combustion chamber is set to 1. 9 and the engine speed is set to 2000 rpm, and the engine is operated at a medium torque or a high torque (that is, the operation during the engine steady operation is performed). Thereafter, the process proceeds to step S69.

  In step S64 following step S54, a high engine output request is made to the engine 10, and in the next step S65, the predetermined ratio (both 50%) and the predetermined lean air-fuel ratio (λ = 1.9). Therefore, the engine output at the time of the high engine output request can be achieved by increasing the engine speed from the predetermined speed (2000 rpm) and setting the amount of increase relative to the predetermined speed to be equal to or less than the set speed. It is determined whether or not there is.

  If the determination in step S65 is NO, the process proceeds to step S68. If the determination in step S65 is YES, the process proceeds to step S66, and the NOx occlusion amount of the NOx occlusion reduction catalyst 82 is greater than the predetermined occlusion amount. It is determined whether or not.

  If the determination in step S66 is YES, the process proceeds to step S68. If the determination in step S66 is NO, the process proceeds to step S67 to execute the first operation, and then proceeds to step S69.

  In step S68 that proceeds when the determination in step S65 is NO and when the determination in step S66 is YES, the second operation is performed, and then the process proceeds to step S69.

  In step S69, the injection amount of the used fuel is calculated from the engine speed, the required engine output, the intake air amount, the excess air ratio λ, the used fuel (ratio), and the like.

  In the next step S70, it is determined whether or not the flag F has become 0. When the determination in step S70 is NO, the process returns to step S51. On the other hand, when the determination in step S70 is YES, FIG. 9 is terminated (the engine 10 is stopped).

  Therefore, in the present embodiment, at the time of the high engine output request, the engine speed is increased above the predetermined speed and the amount of increase with respect to the predetermined speed is increased with the predetermined ratio and the predetermined lean air-fuel ratio. When the engine output at the time of the high engine output request can be achieved by setting the engine speed to be equal to or lower than a preset set engine speed, the engine speed is set to the engine speed with the predetermined ratio and the predetermined lean air-fuel ratio. Since the first operation for increasing the engine output to achievable engine output at the time of high engine output request is performed, the increase amount is small even if the engine speed is increased. It is possible not to give a sense of incongruity due to an increase in sound, and it is possible to suppress deterioration of fuel consumption as much as possible.

  On the other hand, when the high engine output request is made, at the predetermined ratio and the predetermined lean air-fuel ratio, if the amount of increase of the engine speed with respect to the predetermined speed is not larger than the set speed, the high engine output request When the engine output at the time cannot be achieved and the engine output at the time of the high engine output request is increased to an achievable rotation speed, the passenger of the vehicle 1 is given a sense of incongruity due to an increase in engine sound. Therefore, the second operation is performed and the engine is operated at a predetermined rotational speed so as not to give the vehicle occupant an uncomfortable feeling due to an increase in engine sound. However, since the engine output at the time of the high engine output request cannot be achieved in the operation at the predetermined rotation speed, the supply ratio of the first fuel is increased and the combustion air-fuel ratio in the combustion chamber of the engine is set to the stoichiometric air-fuel ratio. The engine output at the time of the high engine output request is achieved. In this case, although the efficiency of the engine is lower than that during the steady operation of the engine, the deterioration of fuel consumption can be suppressed as much as possible by operating the engine at a predetermined rotational speed.

  The present invention is not limited to the embodiment described above, and can be substituted without departing from the spirit of the claims.

  For example, in the above embodiment, the engine 10 is a rotary piston engine, but a reciprocating engine can also be used.

  The above-described embodiments are merely examples, and the scope of the present invention should not be interpreted in a limited manner. The scope of the present invention is defined by the scope of the claims, and all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  The present invention includes an engine configured to be able to supply a first fuel and a second fuel, a generator that is driven by the engine to generate power, a battery that charges power generated by the generator, The present invention is useful for an engine control device of a series hybrid vehicle having a drive motor for driving a vehicle driven by at least one of discharge power and power generated by the generator.

1 series hybrid vehicle 10 engine 20 generator 30 battery 40 drive motor 100 control unit (control means) (remaining battery capacity detection means)
101 Battery current / voltage sensor (Battery remaining capacity detection means)
106 Engine water temperature sensor (engine water temperature detection means)

Claims (5)

An engine configured to be able to supply the first fuel and the second fuel, a generator that is driven by the engine to generate power, a battery that charges the power generated by the generator, the discharged power of the battery, and the above An engine control device for a series hybrid vehicle having a drive motor for driving a vehicle driven by at least one of the electric power generated by a generator,
The first fuel is a fuel having a higher calorific value per unit volume than the second fuel,
Control means for controlling the operation of the engine,
The control means supplies the first and second fuels to the engine at a predetermined ratio and operates the engine at a predetermined rotational speed while setting the combustion air-fuel ratio in the combustion chamber of the engine to a predetermined lean air-fuel ratio. At the time of a high engine output request that requires a higher engine output than during steady engine operation,
With the predetermined ratio and the predetermined lean air-fuel ratio, the engine rotational speed is increased above the predetermined rotational speed, and the amount of increase with respect to the predetermined rotational speed is made equal to or lower than a preset rotational speed, When the engine output at the time of high engine output request is achievable, the engine speed is set to a speed at which the engine output at the time of high engine output request can be achieved with the predetermined ratio and the predetermined lean air-fuel ratio. While performing the first driving to increase,
At the predetermined ratio and the predetermined lean air-fuel ratio, the engine output at the time of the high engine output request cannot be achieved unless the increase amount of the engine speed with respect to the predetermined speed is larger than the set speed. Sometimes, while operating the engine at the predetermined speed, a second fuel supply ratio is made higher than the predetermined ratio, and a combustion air-fuel ratio in the combustion chamber of the engine is set to a stoichiometric air-fuel ratio. An engine control device for a series hybrid vehicle, wherein the engine control device is configured to execute driving. The engine control apparatus for a series hybrid vehicle according to claim 1,
The first fuel is a fuel that has less NOx emission from the engine and lower ignitability than the second fuel under the same combustion air-fuel ratio,
The control means is configured to increase the supply ratio of the first fuel as the engine output at the time of the high engine output request is higher during execution of the second operation. An engine control device for a hybrid vehicle. The engine control device for a series hybrid vehicle according to claim 2,
A NOx storage reduction catalyst provided in the exhaust passage of the engine for purifying exhaust gas of the engine;
The NOx occlusion reduction catalyst occludes NOx in the exhaust gas of the engine in a lean air-fuel ratio atmosphere, and releases and reduces the occluded NOx in a stoichiometric air-fuel ratio atmosphere or a rich air-fuel ratio atmosphere. Yes,
When there is a NOx release request from the NOx occlusion reduction catalyst at the time of the high engine output request, the control means performs the second operation regardless of the condition for executing the first operation or the second operation. An engine control device for a series hybrid vehicle, wherein the engine control device is configured to execute the following operation. The engine control device for a series hybrid vehicle according to claim 2 or 3,
An engine water temperature detecting means for detecting the temperature of the cooling water of the engine;
The control means is configured to reduce the degree of increase in the supply ratio of the first fuel as the temperature of the cooling water by the engine water temperature detection means is lower during execution of the second operation. An engine control device for a series hybrid vehicle. In the engine control device for a series hybrid vehicle according to any one of claims 1 to 4,
A battery remaining capacity detecting means for detecting the remaining capacity of the battery;
The vehicle has a battery traveling mode in which the vehicle is driven by the discharged electric power of the battery, and a charging traveling mode in which the engine is operated and the battery is driven to charge the battery via the generator by the output of the engine. Yes,
When the remaining battery capacity detected by the battery remaining capacity detecting means is lower than a first predetermined value during the battery running mode, the control means switches to the charging running mode, while in the charging running mode. The battery running mode is switched to the battery running mode when the remaining battery capacity detected by the battery remaining capacity detecting means is higher than a second predetermined value set to a value higher than the first predetermined value. Including a switching control unit,
The high engine output request is made when the remaining battery capacity detected by the remaining battery capacity detecting means is set to a value lower than the first predetermined value in the charging travel mode. An engine control device for a series hybrid vehicle, characterized in that it is between the time when the value becomes equal to or less than the value and the value reaches the first predetermined value.

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