JP2017047788A - Engine control device of series hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure, in a series hybrid vehicle, efficiency and combustion stability of an engine by operating the engine at a predetermined rotation speed as long as possible and secure the combustion stability of the engine even when target generation electric power to be generated by a power generator becomes small.SOLUTION: In a case where an engine 10 is operated at a predetermined rotation speed to drive a power generator 20 for target generation electric power to be generated by the power generator 20, when an engine load becomes equal to or more than a predetermined load, the engine rotation speed is set at the predetermined rotation speed, and when an engine load becomes below the predetermined load, the engine rotation speed is reduced from the predetermined rotation speed to a specific rotation speed at which the engine load becomes the predetermined load.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).

JP, 2014-210457, A

  In the above series hybrid vehicle, it is usually preferable that the engine is 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.

  By the way, in the charge travel mode, as the target generated power to be generated by the generator, the engine load (the load of the generator (power generation load)) is predetermined when the generator is driven by operating the engine at the predetermined rotational speed. It is preferable to set so that it becomes more than a load. That is, when the engine load is less than the predetermined load, the combustion stability of the engine is lowered particularly when the engine temperature is low. Therefore, the target generated power is set so that the engine load becomes equal to or higher than the predetermined load. The generator generates the same generated power as the target generated power, a part of the generated power (the required output of the drive motor) is supplied to the drive motor, and the rest is supplied to the battery.

  Here, when the maximum chargeable power is set for the battery from the viewpoint of suppressing the early deterioration of the battery, the charge power to the battery needs to be equal to or less than the maximum chargeable power. When the maximum chargeable power is small, such as when the battery temperature is low, if the required output of the drive motor is small, the charge power to the battery may be greater than the maximum chargeable power.In this case, In order to make the charging power to the battery below the maximum chargeable power, it is necessary to reduce the target generated power. When the generator is driven by operating the engine at the predetermined rotational speed with respect to the target generated electric power thus reduced, the engine load may become a light load less than the predetermined load. If the load is light, the combustion stability of the engine will decrease.

  The present invention has been made in view of such a point, and an object thereof is to ensure engine efficiency and combustion stability in a series hybrid vehicle by operating the engine at a predetermined rotational speed as much as possible. In addition, the combustion stability of the engine is to be ensured even when the target generated power generated by the generator is reduced.

  In order to achieve the above object, according to the present invention, an engine, a generator that is driven by the engine to generate power, a battery that charges power generated by the generator, discharged power of the battery, and the generator Targeting an engine control device for a series hybrid vehicle having a drive motor for driving a vehicle driven by at least one of the generated power, the control means includes a control means for controlling the operation of the engine. When the engine is driven at a predetermined rotational speed and the generator is driven with respect to the target generated power generated by the generator, the engine rotational speed is set to the predetermined speed when the engine load exceeds a predetermined load. On the other hand, when the engine load becomes less than the predetermined load, the engine speed is changed from the predetermined speed to the engine load. Has a configuration that is configured to lower to a certain rotational speed becomes the predetermined load.

  With the above configuration, when the engine is driven at a predetermined rotational speed with respect to the target generated electric power and the generator is driven, when the engine load exceeds the predetermined load, the engine rotational speed is set to the predetermined rotational speed. Thus, the engine can be operated efficiently by setting the predetermined rotational speed to a rotational speed at which the efficiency of the engine is equal to or higher than a predetermined value. In addition, since the engine load is equal to or greater than the predetermined load, combustion stability of the engine can be ensured. On the other hand, when the target generated power becomes small, the engine load becomes less than the predetermined load when the engine is driven at the predetermined rotation speed with respect to the target generated power. Reduces the engine speed from the predetermined speed to the specific speed at which the engine load becomes the predetermined load, so that even if the target generated power is reduced, the combustion stability of the engine can be ensured. it can.

  In the engine control apparatus for a series hybrid vehicle, the engine includes a first fuel injection valve that injects the first fuel to supply the engine, and a second fuel that is less ignitable with respect to the first fuel. A second fuel injection valve that injects the fuel to be supplied to the engine, and the control means controls the operation of the engine including the operation of the first and second fuel injection valves. The predetermined load is changed to a higher value as the volume ratio of the injection amount by the second fuel injection valve to the total injection amount by the first and second fuel injection valves is higher. Is preferred.

  That is, if the injection ratio of the second fuel having low ignitability is high, the combustion stability of the engine becomes low even at the same engine load. Therefore, it is preferable that the predetermined load is high. Therefore, the combustion stability of the engine can be appropriately ensured according to the ignitability of the fuel used.

  The engine control apparatus for the series hybrid vehicle further includes an engine water temperature detecting means for detecting a temperature of the cooling water of the engine, and the control means has a lower temperature of the cooling water detected by the engine water temperature detecting means. The predetermined load is preferably changed to a high value.

  That is, if the engine coolant temperature (that is, the engine temperature) is low, the combustion stability of the engine is low even at the same engine load. Therefore, it is preferable that the predetermined load is high. Therefore, the combustion stability of the engine can be appropriately ensured according to the engine temperature.

  In the engine control apparatus for the series hybrid vehicle, the vehicle has an electric load in addition to the drive motor, and the control means includes a generator control unit that controls the operation of the generator, and power generated by the generator. A power supply control unit that controls supply to the electric load when the specific rotation speed is lower than a preset lower limit rotation speed, the engine rotation speed is set to the lower limit rotation speed. The generator control unit is configured to reduce an engine load when the engine is operated with the engine speed being set to the lower limit speed when the specific speed is lower than the lower limit speed. The power supply control unit is configured to increase the power generation load of the generator so as to be the predetermined load, and the power supply control unit is configured to increase the generated power due to the increase of the power generation load of the generator. Is configured to supply, it is preferred.

  That is, when the engine speed is lower than the lower limit speed, the engine speed may become unstable or a large vibration may occur. For this reason, when the specific rotation speed becomes lower than the lower limit rotation speed, the engine rotation can be stabilized by setting the engine rotation speed to the lower limit rotation speed. However, when the engine speed is set to the lower limit speed, the engine load becomes less than the predetermined load. Therefore, by increasing the power generation load of the generator so that the engine load becomes the predetermined load, the engine load can be made the predetermined load, and the combustion stability of the engine can be ensured. At this time, since the increase in the generated power due to the increase in the power generation load of the generator is supplied to an electric load other than the drive motor, there is no problem even if the power generation load of the generator is increased.

  In one embodiment of the present invention, the electric load is an electric oil pump that supplies oil to the engine.

  In this way, the increase in the generated power due to the increase in the power generation load of the generator is supplied to the electric oil pump that is operated during the operation of the engine, so that the increase in the generated power is reliably consumed by the electric oil pump. Can do. Further, since the supply pressure of the oil to the engine increases due to the supply of the generated power to the electric oil pump, the operating resistance of the engine increases correspondingly, and the engine load is easily increased. Therefore, the increase amount of the power generation load of the generator can be reduced.

  As described above, according to the engine control device for a series hybrid vehicle of the present invention, when the engine is driven at a predetermined rotational speed with respect to the target generated power generated by the generator, the engine is driven. When the load exceeds the predetermined load, the engine speed is set to the predetermined speed. On the other hand, when the engine load is less than the predetermined load, the engine speed is changed from the predetermined speed to the engine load. By reducing the engine speed to a specific rotational speed at which the predetermined load is reached, the engine can be operated at a predetermined rotational speed as much as possible to ensure engine efficiency and combustion stability, and to generate power with a generator. Even if the target generated power is reduced, the combustion stability of the engine can be ensured.

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 temperature of a battery, and the maximum chargeable electric power with respect to this battery. It is a graph which shows the relationship between SOC of a battery and the maximum chargeable electric power with respect to this battery. 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 the 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. Hydrogen gas corresponds to the first fuel, and natural gas corresponds to the second fuel having low ignitability with respect to the first fuel. The second fuel is not limited to natural gas but may be propane or butane, for example. The second fuel is preferably a fuel having a higher calorific value per unit volume than the first fuel, such as natural gas, propane, and butane.

  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 engine control described later in this embodiment, 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 rich air-fuel ratio atmosphere to cause the NOx to react with HC and CO in the exhaust gas. Have the function of reducing

  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.

  In the present embodiment, the hydrogen direct injection valve 18A corresponds to a first fuel injection valve that injects the first fuel to be supplied to the engine 10, and the CNG direct injection valve 18B supplies the second fuel to the engine. 10 corresponds to a second fuel injection valve that injects the fuel to be supplied to the fuel.

  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 includes the operations of the hydrogen direct injection valve 18A (exceptionally the hydrogen port injection valve 17A) and the CNG direct injection valve 18B (exceptionally the CNG port injection valve 17B). A control means for controlling the operation of the generator 20 and a generator control section for controlling the operation of the generator 20 are included.

  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 this charging travel mode, charging of the battery 30 and driving of the drive motor 40 are performed with electric power generated by the generator 20 that generates electric power from 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.

  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.

  Further, the control unit 100 operates the engine 10 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. And the control unit 100 performs the driving | operation of the engine 10 at the time of the said charge driving | running | working mode in any one of the mixing of only natural gas and hydrogen gas and natural gas. In the case of mixing hydrogen gas and natural gas, in this 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%). In the charge travel mode, the required output of the drive motor 40 is the output of the engine at 2000 rpm using only natural gas or hydrogen gas and natural gas (generated power) as in the case where the vehicle 1 is requested to accelerate more than a predetermined value. Is larger than), the shortage is compensated by the discharge power of the battery 30 (not charged). However, if the required output of the drive motor 40 cannot be satisfied even if the discharge power of the battery 30 reaches the maximum dischargeable power of the battery 30, the engine speed is exceptionally made higher than the predetermined speed. .

  In the present embodiment, the remaining amounts of hydrogen gas and natural gas detected by the tank pressure sensor 107 are compared, and when the remaining amount difference between the hydrogen gas and natural gas is equal to or less than a predetermined amount, and the remaining amount When the difference is larger than the predetermined amount and the remaining amount of hydrogen gas is larger, the engine 10 is operated by mixing hydrogen gas and natural gas in the charge travel mode, while the difference in remaining amount is greater than the predetermined amount. When the amount of natural gas is larger than the fixed amount and the remaining amount of natural gas is larger, the engine 10 is operated with natural gas in the charging travel mode. Thus, when the remaining amount of natural gas is larger, the remaining capacity of the battery 30 is quickly recovered from the first predetermined value to a relatively high level by using natural gas in the charging travel mode. be able to. As a result, natural gas can be effectively used to reduce the remaining amount difference.

  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. When the engine is operated at the predetermined rotational speed (2000 rpm) and the difference in the remaining amount is larger than the predetermined amount, the engine 10 is operated with the fuel on the side with the larger remaining amount. When the difference in the remaining amount is not more than the predetermined amount, the engine 10 is operated by mixing hydrogen gas and natural gas (substantially the same volume ratio). In this way, the output of the engine 10 that is operated using the fuel on the remaining amount side, or hydrogen gas and natural gas, and the discharge power of the battery 30 (from the maximum dischargeable power according to the output of the engine 10). To satisfy the required output of the drive motor 40. Even if the discharge power of the battery 30 is set to the maximum dischargeable power, the required output of the drive motor 40 is satisfied in the operation using hydrogen gas or the operation using hydrogen gas and natural gas at substantially the same volume ratio. If this is not possible, at least one of increasing the volume ratio of the natural gas and increasing the engine speed higher than 2000 rpm may be executed. Further, even if the discharge power of the battery 30 is set to the maximum dischargeable power, if the required output of the drive motor 40 cannot be satisfied in the operation using natural gas, the engine speed is set higher than 2000 rpm. May be. As described above, the engine 10 is operated with the fuel with the larger remaining amount, so that the fuel with the larger remaining amount is effectively used, and the difference in the remaining amount between the first fuel and the second fuel is reduced. can do.

  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 first map in the memory of the control unit 100. The control unit 100 uses the first map to detect the relationship between the battery 30 and the battery temperature sensor 109. The maximum dischargeable power is detected from the detected temperature of the battery 30.

  The control unit 100 sets a target generated power to be generated by the generator 20 when the engine 10 is operated. Normally, when the engine 10 is driven at the predetermined rotational speed (2000 rpm) and the generator 20 is driven, the engine generated load (the load of the generator 20 (power generation load)) is equal to or higher than the predetermined load. It is set to such a value. Hereinafter, the target generated power set in this way is referred to as normal target generated power. The predetermined load is a minimum load that can ensure the combustion stability of the engine 10.

  Here, in this embodiment, when the temperature of the battery 30 detected by the battery temperature sensor 109 is lower than a predetermined temperature (for example, a temperature in the range of −10 ° C. to 0 ° C.), as shown in FIG. 30 is set in relation to the temperature of the battery 30 (the relationship in FIG. 3 is stored in the memory of the control unit 100 as the second map), and the temperature of the battery 30 is When the target generated power is the normal target generated power and the required output of the drive motor 40 is small when the maximum chargeable power is lower than the predetermined temperature, the charge power to the battery 30 (target generated power − The required output of the drive motor 40) may be greater than the maximum chargeable power. In this case, in order to make the charging power to the battery 30 equal to or less than the maximum chargeable power, the target generated power needs to be smaller than the normal target generated power. Therefore, when the target generated power is the normal target generated power and the charging power to the battery 30 is larger than the maximum chargeable power, the control unit 100 can charge the battery 30 to the maximum charging power. The target generated power is made smaller than the normal target generated power so as to be equal to or lower than the power. When the engine 10 is operated at the predetermined rotational speed and the generator 20 is driven with respect to the target generated power thus reduced, the engine load may be less than the predetermined load. When the engine load is less than the predetermined load, the combustion stability of the engine 10 is deteriorated particularly when the engine water temperature is low.

  Therefore, in the present embodiment, when the control unit 100 operates the engine 10 at the predetermined rotational speed and drives the generator 20 with respect to the target generated power in the charging travel mode, the engine load is When the engine load exceeds the predetermined load (when the engine torque exceeds the lower limit torque), the engine speed is set to the predetermined engine speed, while when the engine load becomes less than the predetermined load (the engine torque is less than the lower limit torque). The engine speed is reduced from the predetermined rotational speed to a specific rotational speed at which the engine load becomes the predetermined load (the engine torque becomes the lower limit torque). The lower limit torque is an engine torque corresponding to the predetermined load.

  In addition, when the required output of the drive motor 40 exceeds the maximum dischargeable power of the battery 30 in the battery running mode, the control unit 100 adjusts the value of the discharge power of the battery 30 to always adjust the engine load. The load is higher than the set load set to a value higher than the predetermined load. That is, the engine torque is always set to a high torque equal to or higher than the set torque set to a value higher than the lower limit torque. The set torque is an engine torque corresponding to the set load.

  As shown in FIG. 4, the control unit 100 changes the lower limit torque (the predetermined load) to a higher value as the engine water temperature by the engine water temperature sensor 106 is lower. Further, as shown in FIG. 4, the control unit 100 has a natural gas injection ratio that is a volume ratio of the injection amount by the CNG direct injection valve 18B to the total injection amount by the hydrogen and CNG direct injection valves 18A and 18B. The higher the value, the lower limit torque (the predetermined load) is changed to a higher value. In the present embodiment, the natural gas injection ratio is one of 0%, 50%, and 100%, and the lower limit torque (the predetermined load) increases in this order. The lower limit torque, that is, the engine torque that can ensure the combustion stability of the engine 10 varies depending on the engine water temperature and the natural gas injection ratio, and when the engine water temperature is low or the natural gas injection ratio is high, the engine load is the same. Since the combustion stability of the engine 10 is lowered, the lower limit torque is changed as described above. The relationship of FIG. 4 is stored in the memory of the control unit 100 as a third map.

  In the present embodiment, the control unit 100 sets the engine speed to the lower limit speed when the specific speed is lower than a preset lower speed. This lower limit rotational speed is a rotational speed at which the rotation of the engine 10 becomes unstable or a large vibration occurs when the engine rotational speed becomes lower than the lower limit rotational speed. For this reason, it is not preferable to make the engine speed lower than the lower limit speed. Therefore, when the specific rotation speed is lower than the lower limit rotation speed, the engine rotation speed is set to the lower limit rotation speed. However, in this state, the engine load becomes less than the predetermined load (the engine torque becomes less than the lower limit torque).

  Here, the vehicle 1 has an electrical load in addition to the drive motor 40. The control unit 100 also controls the supply of power generated by the generator 20 to the electric load. Thus, the control unit 100 includes a power supply control unit that controls the supply of power generated by the power generator 20 to the electric load.

  The control unit 100 (generator control unit) determines the engine load when the engine 10 is operated with the engine speed set to the lower limit speed when the specific speed is lower than the lower limit speed. The power generation load of the power generator 20 is increased so that the predetermined load is reached (that is, the power generated by the power generator 20 is increased more than the target power generation). Thereby, the combustion stability of the engine 10 is ensured. In addition, the control unit 100 (power supply control unit) supplies an increase in generated power due to an increase in the power generation load of the generator 20 to the electric load. Thereby, even if the power generation load of the generator 20 is increased, the charging power to the battery 30 can be made equal to or less than the maximum chargeable power, and no problem occurs.

  In this embodiment, the electric load to which the increased amount of generated power is supplied is an electric oil pump that supplies oil to the engine 10. The electric oil pump operates by receiving power from a low-voltage battery different from the battery 30 in a normal time when the control unit 100 does not supply the increased amount of generated power. Oil is supplied to the rotor 12 of the engine 10 for cooling, or oil is supplied to the bearing portion that supports the eccentric shaft 13 for lubrication. When the increase in the generated power is supplied to the electric oil pump, more electric power is supplied than the normal time, and the oil supply pressure to the engine 10 is higher than normal. . Thus, by supplying the increased amount of the generated power to the electric oil pump that is operated when the engine 10 is operated, the increased amount of the generated power can be reliably consumed by the electric oil pump. Moreover, since the supply pressure of the oil to the engine 10 is increased by supplying the generated power to the electric oil pump, the operating resistance of the engine 10 is increased correspondingly, and the engine load is easily increased. . Therefore, the increase amount of the power generation load of the generator 20 can be reduced.

  In addition to the electric oil pump, the electric load to which the increased amount of generated power is supplied can be, for example, a seat heater disposed on the seat of the vehicle 1 or other heaters. In particular, when the outside air temperature of the vehicle 1 is considerably low, the specific rotation speed tends to be lower than the lower limit rotation speed, so that the heater can be effectively operated with the increase in the generated power. The generator 20 becomes an electric load when functioning as a motor, but does not become an electric load to which the increased amount of the generated power is supplied.

  Next, the processing operation by the control unit 100 will be described based on the flowcharts of FIGS. 5 is started when an ignition switch (not shown) of the vehicle 1 is turned on. The flowchart of FIG. 6 is a processing operation for controlling the engine 10, and the engine 10 is operated. (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. 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.

  The flowchart of FIG. 6 shows 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. 5 when the engine 10 is operated.

  In the first step S51, various input signals necessary for controlling the engine 10 (particularly, the remaining amounts of hydrogen gas and natural gas from the tank pressure sensor 107, the temperature of the battery 30 from the battery temperature sensor 109, the engine water temperature sensor 106). Engine water temperature).

  In the next step S52, the fuel to be used is determined from the remaining amount difference between hydrogen gas and natural gas, the current value of the flag F, the required output of the drive motor 40, and the like.

  In the next step S53, it is determined whether or not the flag F is 1. When the determination in step S53 is YES, the process proceeds to step S54, while when the determination in step S53 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 S61.

  In step S54, the maximum chargeable power to the battery 30 is set from the temperature of the battery 30 using the second map, and the target generated power is set. This target generated power is the above when the target generated power is the normal target generated power and the charging power to the battery 30 (target generated power—the required output of the drive motor 40) is equal to or less than the maximum chargeable power. When the target generated power is the normal target generated power and the charge power to the battery 30 is larger than the maximum chargeable power, the charge power to the battery 30 is equal to or less than the maximum chargeable power. Therefore, the value is smaller than the normal target generated power.

  In the next step S55, the lower limit torque is set using the third map from the engine water temperature and the natural gas injection ratio by the engine water temperature sensor 106, and in the next step S56, the engine 10 is set for the set target generated power. When the generator 20 is driven by operating at a predetermined rotational speed, it is determined whether the engine torque is equal to or higher than the lower limit torque.

  If the determination in step S56 is YES, the process proceeds to step S62. If the determination in step S56 is NO, the process proceeds to step S57, and the specific rotation speed at which the engine torque becomes the lower limit torque is calculated. The process proceeds to step S58 later.

  In step S58, it is determined whether or not the specific rotation speed is lower than the lower limit rotation speed. When the determination in step S58 is NO, the process proceeds to step S63. On the other hand, when the determination in step S58 is YES, the process proceeds to step S59, where the engine speed is set to the lower limit speed, and in the next step S60. Then, the power generation load of the generator 20 is increased, and the increase in the generated power due to the increase in the power generation load of the power generator 20 is supplied to the electric oil pump. Thereafter, the process proceeds to step S64.

  In step S61, which proceeds when the determination in step S53 is NO, the engine speed is set to the predetermined speed and the engine torque is set to a high torque equal to or higher than the set torque, and then the process proceeds to step S64.

  In step S62 that proceeds when the determination in step S56 is YES, the engine speed is set to the predetermined speed, and then the process proceeds to step S64.

  In step S63, which proceeds when the determination in step S58 is NO, the engine speed is set to the specific speed, and then the process proceeds to step S64.

  In step S64, the amount of fuel used is calculated from the engine speed, engine torque, fuel used (ratio), and the like.

  In the next step S65, it is determined whether or not the flag F has become 0. If the determination in step S65 is NO, the process returns to step S51. If the determination in step S65 is YES, the process in FIG. The operation is terminated (the engine 10 is stopped).

  Therefore, in the present embodiment, when the engine 10 is driven at the predetermined rotational speed and the generator 20 is driven with respect to the target generated power generated by the generator 20, the engine load becomes equal to or higher than the predetermined load. In this case, the engine speed is set to the predetermined speed, and when the engine load becomes less than the predetermined load, the engine speed is determined from the predetermined speed so that the engine load becomes the predetermined load. Since the engine speed is reduced to the rotational speed, the engine 10 is operated at the predetermined rotational speed as much as possible to ensure the efficiency and combustion stability of the engine 10, and the target generated power to be generated by the generator 20 Even if becomes smaller, the combustion stability of the engine 10 can be ensured.

  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 relates to an engine, a generator driven by the engine to generate power, a battery for charging power generated by the power generator, at least one of the discharged power of the battery and the power generated by the power generator. It is useful for an engine control device of a series hybrid vehicle having a drive motor for driving the vehicle driven by

1 series hybrid vehicle 10 engine 18A direct injection valve for hydrogen (first fuel injection valve)
18B CNG direct injection valve (second fuel injection valve)
20 generator 30 battery 40 drive motor 100 control unit (control means)
106 Engine water temperature sensor (engine water temperature detection means)

Claims (5)

Driven by at least one of an engine, a generator that is driven by the engine to generate power, a battery that charges the power generated by the power generator, and a discharge power of the battery and power generated by the power generator An engine control device for a series hybrid vehicle having a drive motor for driving the vehicle,
Control means for controlling the operation of the engine,
In the case where the engine is driven at a predetermined rotational speed and the generator is driven with respect to the target generated power generated by the generator, While the rotation speed is set to the predetermined rotation speed, when the engine load becomes less than the predetermined load, the engine rotation speed is decreased from the predetermined rotation speed to a specific rotation speed at which the engine load becomes the predetermined load. An engine control device for a series hybrid vehicle, characterized in that it is configured as described above. The engine control apparatus for a series hybrid vehicle according to claim 1,
The engine injects a first fuel injection valve for supplying the first fuel to the engine and a second fuel injection for supplying the second fuel having low ignitability to the engine to the engine. A fuel injection valve,
The control means controls the operation of the engine including the operations of the first and second fuel injection valves, and the control means controls the first injection amount with respect to the total injection amount by the first and second fuel injection valves. 2. An engine control device for a series hybrid vehicle, wherein the predetermined load is changed to a higher value as the volume ratio of the injection amount by the fuel injection valve is higher. In the engine control device for a series hybrid vehicle according to claim 1 or 2,
An engine water temperature detecting means for detecting the temperature of the cooling water of the engine;
The control means is configured to change the predetermined load to a higher value as the temperature of the cooling water detected by the engine water temperature detection means is lower. . In the engine control device of the series hybrid vehicle according to any one of claims 1 to 3,
The vehicle has an electrical load other than the drive motor,
The control means includes a generator control unit that controls the operation of the generator, and a power supply control unit that controls supply of electric power generated by the generator to the electric load, and the specific rotational speed is When the engine speed is lower than a preset lower limit speed, the engine speed is set to the lower limit speed.
The generator control unit is configured such that when the specific rotation speed is lower than the lower limit rotation speed, the engine load when the engine is operated with the engine rotation speed set to the lower limit rotation speed becomes the predetermined load. Is configured to increase the power generation load of the generator,
The engine control apparatus for a series hybrid vehicle, wherein the power supply control unit is configured to supply an increase in generated power due to an increase in a power generation load of the generator to the electric load. The engine control device for a series hybrid vehicle according to claim 4,
The engine control device for a series hybrid vehicle, wherein the electric load is an electric oil pump that supplies oil to the engine.

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