JP6135681B2 - Multi-fuel engine control system - Google Patents

Description

  The present invention belongs to a technical field related to a control device for a multi-fuel engine.

  Conventionally, a multi-fuel engine using a first fuel and a second fuel is known. For example, in Patent Document 1, hydrogen, natural gas, alcohols, or the like is used as the first fuel, and as the second fuel, Light oil, gasoline, natural gas, etc. are used. In Patent Document 1, the first fuel is injected into the intake pipe or directly injected into the combustion chamber, and the second fuel is directly injected into the combustion chamber.

JP 2010-14054 A

  By the way, since hydrogen fuel has good ignitability, by performing lean operation, it is possible to achieve emission performance and fuel efficiency comparable to the atmosphere. However, the output performance of the engine is insufficient with only hydrogen fuel. From this, it is conceivable to employ a multi-fuel engine that uses both hydrogen fuel and other fuels as in Patent Document 1.

  However, in order to satisfy any of the emission performance, the fuel consumption performance, and the output performance, there is a problem as to what kind of fuel is used in combination with the hydrogen fuel.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a control device for a multi-fuel engine that has good emission performance, fuel consumption performance, and output performance. is there.

  In order to achieve the above object, according to the present invention, for a control device for a multi-fuel engine mounted on a vehicle, the engine directly injects a first fuel made of hydrogen into a combustion chamber of the engine. In the combustion chamber of the engine 1 and the combustion chamber of the engine, the calorific value per unit volume is high with respect to the first fuel, the NOx emission amount from the engine is small under the same combustion air-fuel ratio, and the lean limit is reached. A second fuel injection valve for directly injecting a second fuel made of gaseous fuel having a low combustion air-fuel ratio, and a supercharger for supercharging intake air into the combustion chamber of the engine, Control means for controlling the operation of the engine including the operation of the second fuel injection valve is provided, and the control means injects the first and second fuels into the combustion chamber of the engine at substantially the same volume ratio. And the The combustion air-fuel ratio in the combustion chamber is set to a lean air-fuel ratio in which the NOx emission amount from the engine is substantially the same as the NOx emission amount when only the second fuel is burned with the lean combustion air-fuel ratio. Therefore, the first and second fuel injection valves are configured to be controlled.

  With the above configuration, the first fuel (hydrogen) and the first fuel have a high calorific value per unit volume, a low NOx emission from the engine under the same combustion air-fuel ratio, and a lean limit combustion air. By injecting the second fuel made of gaseous fuel having a low fuel ratio into the combustion chamber of the engine at substantially the same volume ratio, the combustion air-fuel ratio in the combustion chamber is higher than the lean-limit combustion air-fuel ratio of the second fuel ( A lean air-fuel ratio can be set, and good fuel efficiency can be obtained. Further, the combustion air-fuel ratio in the combustion chamber is set to a lean air-fuel ratio in which the NOx emission amount from the engine is substantially the same as the NOx emission amount when only the second fuel is burned with the lean combustion air-fuel ratio. Therefore, good emission performance can be obtained. Further, the heat generation amount per unit volume of the second fuel is higher than the heat generation amount per unit volume of the first fuel (hydrogen), and both the first and second fuels are directly injected into the combustion chamber and the engine is supercharged. As a result, a good output performance can be obtained.

  In one embodiment of the control apparatus for the multi-fuel engine, the engine is a power generation engine used to drive a generator in a series hybrid system to generate power, and the control means sends the power generation request to the engine. At the time of steady operation at the time, the vehicle is configured to operate at a medium load or a high load that is a load higher than a predetermined load and in a predetermined rotation speed region.

  Thus, in addition to good emission performance and fuel consumption performance, high power generation performance can be obtained. In addition, when the engine is in steady operation at the time of power generation request, the engine can be operated at a high efficiency point by operating at a medium load or a high load and in a predetermined rotation speed region. Can be further improved.

  In the control apparatus for a multi-fuel engine, the supercharger is an exhaust turbocharger having a turbine disposed in an exhaust passage of the engine and a compressor disposed in an intake passage of the engine and coupled to the turbine. When the engine is started due to the establishment of a predetermined condition when the engine is stopped, the control means performs combustion in the combustion chamber during a predetermined period from the start of the engine to before ignition. By injecting the first and second fuels from the first and second fuel injection valves so that the air-fuel ratio becomes the lean air-fuel ratio, unburned gas is introduced upstream of the turbine in the exhaust passage. The unburned gas accumulation control to be accumulated is executed, and after the unburned gas accumulation control is executed, the combustion air fuel ratio in the combustion chamber is set to the lean air fuel ratio. 1 and the second from the fuel injection valve the first and second fuel is injected, respectively and is configured to perform ignition, it is preferable.

  In this way, when the high-temperature gas combusted in the combustion chamber by the ignition after execution of the unburned gas accumulation control is exhausted to the exhaust passage, the exhaust gas accumulates on the upstream side of the turbine in the exhaust passage. The unburned gas is combusted at once, which allows the turbine to rotate vigorously. As a result, a high boost pressure can be obtained immediately after the engine is started.

  In the case of the configuration for executing the unburned gas accumulation control as described above, the control means performs the unburned gas accumulation control at the time of starting the engine when the vehicle is requested to accelerate more than a predetermined value as the predetermined condition. Are preferably configured to perform.

  This makes it possible to immediately obtain a supercharging pressure corresponding to the acceleration request when the vehicle requests acceleration more than a predetermined value, thereby realizing smooth vehicle acceleration. In particular, when the engine is the power generation engine, the power generated by the generator can be immediately supplied to the vehicle drive motor at the time of the acceleration request, and the vehicle drive motor is generated by the generated power and the discharge power of the battery. High acceleration performance can be obtained by driving.

  Further, in the case of the configuration for executing the unburned gas accumulation control as described above, the control device further includes a motor for starting the engine, and the control means further controls the motor when the predetermined condition is satisfied. When the engine is started, the engine speed driven by the motor is preferably configured to be higher than when the engine is started when the predetermined condition is not satisfied.

  As a result, the smoother vehicle acceleration can be realized by increasing the pre-rotation by the motor.

  In the case of the configuration of the embodiment in which the engine is the power generation engine, the supercharger is disposed in the exhaust passage of the engine and the intake passage of the engine. An exhaust turbocharger having a connected compressor, and the engine further includes a NOx occlusion reduction catalyst disposed on a downstream side of the turbine in the exhaust passage and 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 the occluded NOx in a rich air-fuel ratio atmosphere. When NOx is released from the NOx occlusion reduction catalyst, the engine is put into a no-load operation and the combustion air-fuel ratio in the combustion chamber of the engine is set to a rich air-fuel ratio. In addition, when there is an acceleration request for the vehicle more than a predetermined time between the start of NOx release and a predetermined time before completion of NOx release, the ignition is stopped from the time before the predetermined time before completion of NOx release. Then, the first and second fuels are injected from the first and second fuel injection valves so that the combustion air-fuel ratio in the combustion chamber becomes the rich air-fuel ratio, respectively. The unburned gas accumulation control for accumulating unburned gas upstream is executed, and after the unburned gas accumulation control is executed, the first and second combustion air fuel ratios in the combustion chamber become the lean air fuel ratio. The first and second fuels may be respectively injected from the fuel injection valve to restart the ignition.

  As a result, when high-temperature gas combusted in the combustion chamber by re-ignition after execution of unburned gas accumulation control is exhausted into the exhaust passage, the exhaust gas accumulates on the upstream side of the turbine in the exhaust passage. Unburned gas burns at once. As a result, a high supercharging pressure can be obtained as early as possible when the vehicle is requested to accelerate more than a predetermined amount when NOx is released (during no-load operation). Moreover, the release of NOx can be completed by the burned gas of the unburned gas.

  In the case of the configuration of the above-described embodiment, the supercharger has an exhaust turbo including a turbine disposed in the exhaust passage of the engine and a compressor disposed in the intake passage of the engine and connected to the turbine. The supercharger further includes a heating device that heats the vehicle interior of the vehicle using the cooling water of the engine, and the control means causes the engine to move from the predetermined load during a heating request without a power generation request. And when the vehicle is requested to accelerate more than a predetermined amount during the light load operation, the ignition is stopped for a predetermined period after the acceleration request. By injecting the first and second fuels from the first and second fuel injection valves so that the combustion air-fuel ratio of the engine becomes the lean air-fuel ratio, the tar in the exhaust passage The unburned gas accumulation control for accumulating the unburned gas upstream of the combustion chamber is executed, and after the unburned gas accumulation control is executed, the first and the first and the first and second so that the combustion air-fuel ratio in the combustion chamber becomes the lean air-fuel ratio. The first and second fuels may be respectively injected from the second fuel injection valve to restart ignition.

  As a result, when high-temperature gas combusted in the combustion chamber due to reignition after execution of unburned gas accumulation control is exhausted into the exhaust passage, the exhaust gas accumulates upstream of the turbine in the exhaust passage. Unburned gas burns at once. As a result, when the vehicle is requested to accelerate more than a predetermined amount during light load operation, a high boost pressure can be obtained immediately.

  In the case of the configuration for executing the unburned gas accumulation control as described above, the control means sets the injection amounts of the first and second fuels from substantially the same volume ratio when the unburned gas accumulation control is performed. It is preferable that the volume ratio of the injection quantity of the first fuel is changed and the volume ratio of the injection quantity of the second fuel is increased.

  As described above, when the unburned gas accumulation control is performed, the volume ratio of the injection amount of the second fuel having a high calorific value per unit volume is increased, whereby the turbine is rotated more vigorously due to the combustion of the unburned gas. Can be made.

  As described above, according to the control device for a multi-fuel engine of the present invention, the engine directly injects the first fuel made of hydrogen into the combustion chamber of the engine, and the engine. In the combustion chamber, the first fuel is composed of a gaseous fuel that has a high calorific value per unit volume, a low NOx emission from the engine under the same combustion air-fuel ratio, and a low lean-limit combustion air-fuel ratio. A second fuel injection valve for directly injecting fuel, and a supercharger, injecting the first and second fuels into the combustion chamber of the engine at substantially the same volume ratio, and the combustion The indoor combustion air-fuel ratio is set to a lean air-fuel ratio so that the NOx emission amount from the engine is substantially the same as the NOx emission amount when only the second fuel is burned with the lean combustion air-fuel ratio. To do Ri, emission performance, any performance of fuel consumption performance and output performance and it becomes possible to improve.

It is the schematic of the vehicle carrying the multi-fuel engine controlled by the control apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the engine of the said 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. 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. 3 is a flowchart showing processing operations at the time of engine start and operation by the control unit in the first embodiment. 6 is a flowchart illustrating processing operations at the time of engine start and operation by a control unit in the second embodiment. 10 is a flowchart showing processing operations at the time of engine start and operation by a control unit in the third embodiment.

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

(Embodiment 1)
FIG. 1 is a schematic diagram of a vehicle 1 equipped with a multi-fuel engine 10 (hereinafter referred to as an engine 10) controlled by a control device according to Embodiment 1 of the present invention. The vehicle 1 is a so-called range extender EV vehicle (also referred to as a vehicle having a series hybrid system (series hybrid vehicle)), and includes an engine 10, a generator 20 driven by the engine 10 to generate electric power, A high-voltage / large-capacity battery 30 in which the power generated by the generator 20 is stored (charged), and the generated power of the generator 20 driven by the engine 10 and the stored power (discharged power) of the battery 30 A drive motor 40 that is driven by both or only the discharge power of the battery 30 is provided. 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 drive motor 40 is basically driven by the discharge power of the battery 30, and the output of the drive motor 40 is insufficient with only the discharge power of the battery 30, such as when the vehicle 1 is requested to accelerate the vehicle 1. Sometimes, the engine 10 is started and the power generated by the generator 20 is also supplied to the drive motor 40. 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, so that the battery 30 is charged with the generated power (regenerative power). When the remaining capacity (SOC) of the battery 30 falls below a predetermined capacity, the engine 10 is started and the battery 30 is charged with the generated power of the generator 20. The predetermined capacity is a capacity that is higher than the level that requires urgently required charging of the battery 30, and is a capacity that can be maintained at an appropriate level that is not too low and not too high as the remaining capacity of the battery 30. is there. 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 has a higher calorific value per unit volume and lower NOx emission from the engine 10 (combustion chamber) under the same combustion air-fuel ratio than the first fuel. Further, it corresponds to a second fuel made of a gaseous fuel having a low lean limit combustion air-fuel ratio. The second fuel is not limited to natural gas but may be propane or butane, for example.

  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. On the upstream side of the branch portion of the intake passage 14 (upstream side of a compressor 85a of an exhaust turbocharger 85 to be described later), the intake passage 14 is driven by a throttle valve actuator 90 such as a stepping motor and has a cross-sectional area ( A throttle valve 16 for adjusting the valve opening) 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 of the rotor housings 11 (each cylinder), hydrogen direct injection valve 18A (first cylinder) 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. 1) and a CNG direct injection valve 18B (second fuel injection) 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. Valve) and two spark plugs 19 for igniting hydrogen gas and natural gas injected from hydrogen and CNG direct injection valves 18A and 18B, respectively. Hydrogen gas and natural gas are injected into the combustion chamber at substantially the same volume ratio except during unburned gas accumulation control described later.

  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 85 a disposed on the downstream side of the throttle valve 16 in the intake passage 14 and a downstream side of the merging portion in the exhaust passage 15 and an upstream side 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 on the downstream side of the compressor 85a in the intake passage 14, and then in the intake chamber in each rotor accommodating chamber 11a via each branch path. Inhaled. 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 for detecting the temperature of the engine coolant (engine water temperature), the pressure in the hydrogen tank 70 (that is, the hydrogen gas remaining amount in the hydrogen tank 70), and the pressure in the CHG tank 71 (that is, in the CNG tank 71) A tank pressure sensor 107 (which is provided separately for the hydrogen tank 70 and the CNG tank 71), and an air flow sensor 108 for detecting the intake air flow rate sucked into the intake passage 14. A control unit 100 that performs operation control of the engine 10, operation control of the first and second inverters 50 and 51 (that is, operation control of the generator 20 and the drive motor 40), and the like is provided. The rotation angle sensor 104 also serves as an engine rotation speed sensor that detects the rotation speed of the engine 10. In FIG. 2, reference numeral 55 denotes an operation switch provided in the heating device in Embodiment 3 to be described later and operated by an occupant of the vehicle 1 to operate the heating device.

  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, and the like. An information signal is 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 including the operations of the hydrogen direct injection valve 18A and the CNG direct injection valve 18B.

  The control unit 100 controls the first and second inverters 50 and 51 to generate power from the generator 20 and the first mode in which the drive motor 40 is driven only with the discharged power from the battery 30 with the engine 10 stopped. A second mode in which the drive motor 40 is driven with the discharge power from the battery 30 while charging the battery 30 with the power, and a third mode in which the drive motor 40 is driven with the power from both the battery 30 and the generator 20. Switch to the mode. In this third mode, all of the power generated by the generator 20 is supplied to the drive motor 40, and a part of the power generated by the generator 20 is supplied to the drive motor 40 while the rest is supplied to the battery 30. Is included.

  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. Then, the control unit 100 selects the first mode when the SOC of the battery 30 is higher than the predetermined capacity, and the acceleration request of the vehicle 1 more than the predetermined even if the SOC of the battery 30 is higher than the predetermined capacity. In the case where the required output of the drive motor 40 based on the signals from the accelerator opening sensor 102 and the vehicle speed sensor 103 is large as in the case where there is, the third mode is selected. Further, the control unit 100 selects the second mode when the SOC of the battery 30 is not more than the predetermined capacity. It should be noted that when the remaining amount of hydrogen gas in the hydrogen tank 70 by the tank pressure sensor 107 is equal to or lower than a preset first set value, or the remaining amount of natural gas in the CNG tank 71 is set to a second preset value. The first mode is selected when the set value or less is reached.

  When the engine 10 is in a stopped state, the control unit 100 determines whether or not there is an operation request for the engine 10 based on the required output of the drive motor 40 and the SOC value of the battery 30 (in this embodiment, whether or not there is a power generation request). If the engine 10 is requested to operate (power generation request), the engine 10 is cranked by the generator 20 as a motor and the engine 10 is started. The engine 10 is operated to generate power.

  When the engine 10 is in operation, the control unit 100 injects hydrogen gas and natural gas into the combustion chamber of the engine 10 at substantially the same volume ratio, and sets the combustion air-fuel ratio in the combustion chamber to the engine 10 (combustion chamber). In order to obtain a lean air-fuel ratio so that the NOx emission amount from the combustion chamber is substantially the same as the NOx emission amount when only natural gas is burned with the lean combustion air-fuel ratio, the direct injection valve 18A for hydrogen and CNG , 18B are controlled.

  When the engine 10 is operated in response to an operation request (power generation request) for the engine 10, the control unit 100 basically performs a steady operation unless there is a request for acceleration of the vehicle 1 or more. When the control unit 100 operates in a steady state at the time of a power generation request in this manner, the control unit 100 operates at a medium load or a high load that is a load higher than a predetermined load and in a predetermined rotation speed region. In the present embodiment, the predetermined rotational speed region is an efficient region including the highest efficiency point of the engine 10 (for example, 1800 rpm to 2200 rpm). In the present embodiment, the predetermined rotational speed region is basically operated at 2000 rpm.

  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 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 and FIG. 4, the lean air limit combustion air-fuel ratio (here, the excess air ratio λ) of natural gas is 1.6, and even if the excess air ratio λ is larger than this, stable ignition is achieved. I can't do it. 3 and 4, 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. In FIGS. 3 and 4, 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. .

  Therefore, in this embodiment, the combustion air-fuel ratio (excess air ratio λ) in the combustion chamber is set so that the NOx emission amount from the engine 10 is only natural gas with the lean-limit combustion air-fuel ratio (λ = 1.6). The lean air-fuel ratio is made substantially the same as the NOx emission amount when burned. 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.

  Next, processing operations when the engine 10 is started and operated by the control unit 100 will be described based on the flowchart of FIG.

  In the first step S1, signals from various sensors are read, and in the next step S2, 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 S3, based on the required output of the drive motor 40 and the SOC of the battery 30, the presence or absence of an operation request for the engine 10 is confirmed. In the next step S4, it is determined whether or not there is an operation request for the engine 10. judge.

  When the determination in step S4 is NO, the process returns to step S1. On the other hand, when the determination in step S4 is YES, the process proceeds to step S5 to determine whether or not a predetermined condition is satisfied (in this embodiment, the vehicle 1 Whether or not there is an acceleration request greater than or equal to a predetermined value). That is, it is determined whether or not the engine 10 is to be started when a predetermined condition is satisfied (acceleration request exceeding a predetermined value of the vehicle 1) when the engine 10 is stopped.

  When the determination in step S5 is NO, the process proceeds to step S6 where the engine 10 is cranked by the generator 20 as a motor (no fuel injection is performed), and in the next step S7, the rotational speed of the engine 10 is 500 rpm. It is determined whether or not the number is exceeded.

  When the determination at step S7 is NO, the processing operation at step S7 is repeated. When the determination at step S7 is YES, the process proceeds to step S10.

  On the other hand, when the determination in step S5 is YES, the process proceeds to step S8 where the engine 10 is cranked by the generator 20 as a motor and unburned gas accumulation control is executed. In the unburned gas accumulation control, the combustion air-fuel ratio in the combustion chamber of the engine 10 is the lean air-fuel ratio (λ = 1.9) in a predetermined period from the start of engine 10 (start of cranking) to before ignition. By injecting hydrogen gas and natural gas from the hydrogen and CNG direct injection valves 18A and 18B, respectively, the unburned gas is accumulated in the exhaust passage 15 upstream of the turbine 85b. That is, since hydrogen gas and natural gas supplied into the combustion chamber are not ignited, they are discharged into the exhaust passage 15 unburned, and the unburned gas is accumulated in the exhaust passage 15 upstream of the turbine 85b. become.

  In the present embodiment, the predetermined period is a period from the start of engine 10 to immediately before ignition (all periods of cranking). However, the unburned gas is introduced into the exhaust passage 15 upstream of the turbine 85b. As long as the gas 85 can be accumulated by an amount capable of vigorously rotating the turbine 85b, it may be a partial period of the entire cranking period.

  By accumulating unburned gas in the upstream side of the turbine 85b in the exhaust passage 15 in this way, when high-temperature gas combusted in the combustion chamber by ignition in step S10 described later is exhausted to the exhaust passage 15. The accumulated unburned gas is burned at a time by the exhaust gas, and the turbine 85b can be rotated vigorously.

  During execution of the unburned gas accumulation control, hydrogen gas and natural gas may be injected at substantially the same volume ratio, but in the present embodiment, the injection amounts of hydrogen gas and natural gas are set at substantially the same volume ratio. The volume ratio of the hydrogen gas injection amount is decreased and the volume ratio of the natural gas injection amount is increased (in this embodiment, the hydrogen gas injection amount: natural gas injection amount = 20: 80). To do). When the volume ratio of the natural gas injection amount is increased without changing the lean air-fuel ratio, the NOx emission amount is reduced as compared with the case of substantially the same volume ratio, and the turbine 85b is further increased by the combustion of the unburned gas. It can be rotated vigorously. If the volume ratio of the injection amount of natural gas is increased as in this embodiment (80%), combustion in the combustion chamber may not exceed the lean limit of the mixed gas, but the above accumulation may occur. Since the burned unburned gas is burned by the high-temperature gas burned in the combustion chamber, there is no problem that it does not burn.

  In the next step S9, it is determined whether or not the rotational speed of the engine 10 has exceeded 1000 rpm. If the determination in step S9 is NO, the processing operation in step S9 is repeated, and if the determination in step S9 is YES, Proceed to step S10. As described above, in the present embodiment, when the engine 10 is started when the vehicle 1 is requested to accelerate more than a predetermined value (when a predetermined condition is satisfied), the rotational speed of the engine 10 driven by the generator 20 is set to the acceleration. It is higher than when the engine 10 is started when there is no request (when the predetermined condition is not satisfied).

  In the present embodiment, the unburned gas accumulation control is executed when the engine 10 is started when the predetermined condition that there is a predetermined acceleration request of the vehicle 1 is satisfied. When the engine 10 is started, unburned gas accumulation control may be executed.

  In step S10, hydrogen gas and natural gas are supplied from the hydrogen and CNG direct injection valves 18A and 18B so that the combustion air-fuel ratio in the combustion chamber becomes the lean air-fuel ratio (λ = 1.9). Therefore, each is injected and ignited.

  In the next step S11, it is determined whether or not the required output of the drive motor 40 is smaller than a predetermined value. This predetermined value is such that if the required output of the drive motor 40 is larger than this, the rotational speed of the engine 10 needs to be larger than 2000 rpm so that the required output of the drive motor 40 can be accommodated.

  When the determination in step S11 is NO, the process proceeds to step S12, in which the target rotational speed of the engine 10 is set to a higher value as the required output of the drive motor 40 is larger, and in response to the required output of the drive motor 40. Set the target boost pressure. At this time, the injection amounts of hydrogen gas and natural gas are set to substantially the same volume ratio (both are about 50%), and the combustion air-fuel ratio in the combustion chamber is set to the lean air-fuel ratio (λ = 1.9). As described above, when there is a request for acceleration of the vehicle 1 or more, the determination in step S11 is NO, and the process proceeds to step S12. After step S12, the process proceeds to step S14.

  On the other hand, when the determination in step S11 is YES, the process proceeds to step S13, where the target rotational speed of the engine 10 is set to 2000 rpm, and the target boost pressure corresponding to the required output of the drive motor 40 is set. Also at this time, the injection amounts of hydrogen gas and natural gas are set to substantially the same volume ratio (both are about 50%), and the combustion air-fuel ratio in the combustion chamber is set to the lean air-fuel ratio (λ = 1.9). In step S13, the engine 10 is steadily operated. After step S13, the process proceeds to step S14.

  In step S14, signals from various sensors are newly read and the presence or absence of the engine request operation is newly confirmed, and it is determined whether or not there is no operation request for the engine 10. When the determination in step S14 is NO, the process returns to step S11. On the other hand, when the determination in step S14 is YES, the process proceeds to step S15, the engine 10 is stopped, and then the process returns.

  Therefore, in the present embodiment, the hydrogen gas and the calorific value per unit volume of the hydrogen gas are high, the NOx emission amount from the engine 10 is small under the same combustion air-fuel ratio, and the lean-limit combustion air-fuel ratio is low. Since natural gas is injected into the combustion chamber of the engine 10 at substantially the same volume ratio, the combustion air-fuel ratio in the combustion chamber is made higher (lean) than the lean-limit combustion air-fuel ratio of natural gas. It can be set and good fuel economy performance can be obtained. Further, the combustion air-fuel ratio in the combustion chamber is set to a lean air-fuel ratio in which the NOx emission amount from the engine 10 is substantially the same as the NOx emission amount when only natural gas is burned with the lean combustion air-fuel ratio. Therefore, good emission performance can be obtained. Further, the calorific value per unit volume of natural gas is higher than the calorific value per unit volume of hydrogen gas, and both hydrogen gas and natural gas are directly injected into the combustion chamber, and the engine 10 causes the exhaust turbocharger 85 to Therefore, good output performance can be obtained.

  Further, in the present embodiment, the unburned gas accumulation control is executed when the engine 10 is started when a predetermined condition that the vehicle 1 has a predetermined acceleration request or more is satisfied. By exhausting the high-temperature gas combusted in the combustion chamber by ignition after execution into the exhaust passage 15, the unburned gas accumulated on the upstream side of the turbine 85b in the exhaust passage 15 can be burned all at once. The turbine 85b can be vigorously rotated, and a high supercharging pressure can be obtained immediately after the engine 10 is started.

(Embodiment 2)
FIG. 6 shows processing operations at the time of start-up and operation of the engine 10 by the control unit 100 according to the second embodiment of the present invention. When NOx is released from the NOx storage reduction catalyst 82 (NOx purge), the vehicle 1 The processing operation when there is a predetermined acceleration request or higher is shown.

  Also in the present embodiment, the hardware configuration is the same as that of the first embodiment. Also in the present embodiment, as in the first embodiment, when the engine 10 is operated, the control unit 100 injects hydrogen gas and natural gas into the combustion chamber of the engine 10 at substantially the same volume ratio, and The combustion air-fuel ratio in the combustion chamber is equal to the lean air-fuel ratio (λ) in which the NOx emission amount from the engine 10 is substantially the same as the NOx emission amount when only natural gas is burned with the lean combustion air-fuel ratio. = 1.9), the hydrogen and CNG direct injection valves 18A and 18B are controlled. However, as will be described later, when NOx is released from the NOx occlusion reduction catalyst 82 (at the time of NOx release control described later), the combustion air-fuel ratio in the combustion chamber is set to a rich air-fuel ratio (λ = 0.9).

  In the present embodiment, the control unit 100 executes NOx release control for releasing NOx from the NOx storage reduction catalyst 82 when the NOx storage amount of the NOx storage reduction catalyst 82 becomes a predetermined amount or more. The predetermined amount is close to a level at which NOx can no longer be occluded, and is an amount that requires the occlusion of the occluded NOx. The NOx occlusion amount of the NOx occlusion reduction catalyst 82 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 determines that NOx release is complete when a preset time t1 has elapsed from the start of NOx release, and stops NOx release control. The set time t1 is a time (for example, 10 s) required to release substantially the entire amount of NOx stored in the NOx storage reduction catalyst 82 by the NOx release control.

  During the NOx release control, the control unit 100 puts the engine 10 into a no-load operation and sets the combustion air-fuel ratio in the combustion chamber of the engine 10 to a rich air-fuel ratio (λ = 0.9). At this time, the control unit 100 drives the engine 10 by the generator 20 so as to maintain the rotational speed of the engine 10 at 2000 rpm. As a result, there is no change in the engine sound that accompanies the execution of the NOx release control, and the passenger of the vehicle 1 does not feel uncomfortable.

  In addition, when there is an acceleration request for the vehicle 1 that is greater than or equal to a predetermined time t2 between the start of NOx release by the NOx release control and a predetermined time t2 before completion of NOx release, the control unit 100 performs the predetermined time t2 of completion of NOx release. From the previous time point, from the hydrogen and CNG direct injection valves 18A and 18B so that the combustion air-fuel ratio in the combustion chamber of the engine 10 becomes the rich air-fuel ratio (λ = 0.9) with the ignition stopped. By injecting hydrogen gas and natural gas, unburned gas accumulation control is performed to accumulate unburned gas on the upstream side of the turbine 85b in the exhaust passage 15. Similar to the unburned gas accumulation control of the first embodiment, in the unburned gas accumulation control of the present embodiment, the injection amount of hydrogen gas and natural gas is changed from substantially the same volume ratio, and the injection amount of hydrogen gas is changed. The volume ratio of the natural gas and the volume ratio of the natural gas injection amount are increased. However, in this embodiment, the volume ratio of the injection amount of natural gas is increased as the required acceleration is larger. Further, the control unit 100 drives the engine 10 by the generator 20 so as to maintain the rotational speed of the engine 10 at 2000 rpm in the unburned gas accumulation control as in the NOx release control.

  The control unit 100 then performs the direct injection valve 18A for hydrogen and CNG so that the combustion air-fuel ratio in the combustion chamber becomes the lean air-fuel ratio (λ = 1.9) after execution of the unburned gas accumulation control. , 18B, hydrogen gas and natural gas are respectively injected to restart ignition. When the high-temperature gas combusted in the combustion chamber by this re-ignition is exhausted into the exhaust passage 15, unburned gas accumulated on the upstream side of the turbine 85 b in the exhaust passage 15 is combusted at once by the exhaust gas. As a result, a high boost pressure can be obtained as early as possible when the vehicle 1 is requested to accelerate more than a predetermined value when NOx is released (during no-load operation). Moreover, the release of NOx can be completed by the burned gas of the unburned gas. That is, since the NOx release control for (t1-t2) time has already been performed, the combustion of the unburned gas accumulated at the predetermined time t2 is the same as the NOx release control for t1 time. Release can be completed. The predetermined time t2 is as short as possible so that the unburned gas can be accumulated upstream of the turbine 85b in the exhaust passage 15 so that the turbine 85b can be vigorously rotated by combustion of the unburned gas. It is preferable to do.

  The control by the controller 100 will be specifically described based on the flowchart of FIG.

  In steps S31 to S34, processing operations similar to those in S1 to S4 of the first embodiment are performed.

  In step S35 that proceeds when the determination in step S34 is YES, the engine 10 is started. Here, the engine 10 is started by operating in steps S6, S7 and S10 of the first embodiment.

  In the next step S36, it is determined whether or not the required output of the drive motor 40 is smaller than a predetermined value (the same value as the predetermined value in the first embodiment (step S11)), and the determination in step S36 is NO. In some cases, the process proceeds to step S37, where the target rotational speed of the engine 10 is set to a higher value as the required output of the drive motor 40 is larger, and is set to a target boost pressure corresponding to the required output of the drive motor 40. . At this time, the injection amounts of hydrogen gas and natural gas are set to substantially the same volume ratio (both are about 50%), and the combustion air-fuel ratio in the combustion chamber is set to the lean air-fuel ratio (λ = 1.9). After step S37, the process proceeds to step S40.

  When the determination in step S36 is YES, the process proceeds to step S38, where the target rotational speed of the engine 10 is set to 2000 rpm, and the target supercharging pressure corresponding to the required output of the drive motor 40 is set. Also at this time, the injection amounts of hydrogen gas and natural gas are set to substantially the same volume ratio (both are about 50%), and the combustion air-fuel ratio in the combustion chamber is set to the lean air-fuel ratio (λ = 1.9). In step S38, the engine 10 is steadily operated.

  In the next step S39, it is determined whether or not the NOx occlusion amount of the NOx occlusion reduction catalyst 82 is equal to or greater than the predetermined amount. If the determination in step S39 is no, the process proceeds to step S40. In this step S40, signals from various sensors are newly read and the presence or absence of the engine request operation is newly confirmed, and it is determined whether or not the operation request for the engine 10 has been lost. If the determination in step S40 is no, the process returns to step S36.

  On the other hand, when the determination in step S40 is YES, the process proceeds to step S41, the engine 10 is stopped, and then the process returns.

  When the determination in step S39 is YES, the process proceeds to step S42 to execute NOx release control, and in the next step S43, from the start of NOx release to the predetermined time t2 before the completion of NOx release (NOx release start). Until (t1-t2) time elapses), it is determined whether or not the vehicle 1 has been requested to accelerate more than a predetermined value.

  When the determination in step S43 is NO, the process proceeds to step S44 to determine whether or not NOx release has been completed (whether t1 time has elapsed since the start of NOx release). When the determination at step S44 is NO, the processing operation at step S44 is repeated, while when the determination at step S44 is YES, the process proceeds to step S40.

  On the other hand, when the determination in step S43 is YES, the process proceeds to step S45, and it is determined whether (t1-t2) time has elapsed since the start of NOx release. If the determination in step S45 is NO, the processing operation in step S45 is repeated. If the determination in step S45 is YES, the process proceeds to step S46, and the unburned gas accumulation control is executed. After step S46, the process returns to step S36. As described above, when the process returns from step S46 to step S36, the determination in step S36 is NO, and the process proceeds to step S37.

  Therefore, in the present embodiment, when there is an acceleration request for the vehicle 1 more than a predetermined time between the start of NOx release by the NOx release control and the predetermined time t2 before the completion of NOx release, the predetermined time t2 before the completion of NOx release. From the point of time, when the ignition is stopped, the hydrogen and CNG direct injection valves 18A and 18B provide hydrogen so that the combustion air-fuel ratio in the combustion chamber of the engine 10 becomes the rich air-fuel ratio (λ = 0.9). By injecting the gas and the natural gas, unburned gas accumulation control for accumulating unburned gas on the upstream side of the turbine 85b in the exhaust passage 15 is executed, and after executing the unburned gas accumulation control, Hydrogen gas and natural gas are respectively injected from the hydrogen and CNG direct injection valves 18A and 18B so that the combustion air-fuel ratio becomes the lean air-fuel ratio (λ = 1.9). Since the ignition is restarted, a high supercharging pressure can be obtained as soon as possible when the vehicle 1 is requested to accelerate more than a predetermined value when NOx is released (during no-load operation). Moreover, the release of NOx can be completed by the burned gas of the unburned gas. Note that even if there is a request for acceleration of the vehicle 1 or more during NOx release control, a high boost pressure cannot be obtained until the NOx release control is substantially completed, but until then, the battery 30 is discharged. Respond as much as possible to acceleration demands with electric power.

(Embodiment 3)
FIG. 7 shows processing operations at the time of starting and operation of the engine 10 by the control unit 100 in Embodiment 3 of the present invention, and processing when there is a request for acceleration of the vehicle 1 or more during heating operation control. The operation is shown.

  This embodiment is different from the first and second embodiments in that the vehicle 1 is provided with a heating device, but the other hardware configuration is the same as the first and second embodiments. In the first and second embodiments as well, the vehicle 1 is provided with a heating device, and when the heating operation control and the heating operation control as described in the present embodiment are performed, there is a request for acceleration of the vehicle 1 more than a predetermined value. The control at that time may be executed.

  Also in this embodiment, as in Embodiments 1 and 2, the control unit 100 injects hydrogen gas and natural gas into the combustion chamber of the engine 10 at substantially the same volume ratio when the engine 10 is in operation. In addition, the combustion air-fuel ratio in the combustion chamber has a lean air-fuel ratio in which the NOx emission amount from the engine 10 is substantially the same as the NOx emission amount when only natural gas is burned with the combustion air-fuel ratio at its lean limit. In order to make (λ = 1.9), the hydrogen and CNG direct injection valves 18A and 18B are controlled. However, as in the second embodiment, during the NOx release control, the combustion air-fuel ratio in the combustion chamber is set to a rich air-fuel ratio. Further, also in the present embodiment, as in the second embodiment, the control unit 100 determines that the NOx occlusion amount of the NOx occlusion reduction catalyst 82 is a predetermined amount (the same value as the predetermined amount in the second embodiment (step S39)). When this is the case, NOx release control is executed.

  The heating device is a device that heats the passenger compartment of the vehicle 1 using the cooling water of the engine 10. This heating device may be incorporated as an air conditioner. This heating device includes a heater core that performs heat exchange between the air blown into the passenger compartment and the cooling water, and an operation switch 55 (shown in FIG. 2) that is operated by an occupant of the vehicle 1 to operate the heating device. The operation information of the operation switch 55 is input to the control unit 100. If there is no power generation request and the engine 10 is stopped, and the heating request is made by the operation switch 55, the control unit 100 starts the engine 10 and warms the cooling water of the engine 10. At this time, the control unit 100 executes the heating operation control in which the engine 10 is operated with a light load that is smaller than the predetermined load (the minimum value of the load when performing steady operation when generating power). That is, the cooling water of the engine 10 is warmed by operating the engine 10 while generating power slightly by the generator 20.

  During the heating operation control, the control unit 100 sets the engine 10 to the light load operation and sets the combustion air-fuel ratio in the combustion chamber of the engine 10 to the lean air-fuel ratio (λ = 1.9). At this time, the control unit 100 drives the engine 10 by the generator 20 so as to maintain the rotational speed of the engine 10 at 2000 rpm.

  When the vehicle 1 is requested to accelerate more than a predetermined value during the heating operation control (light load operation), the control unit 100 stops the ignition for a predetermined period after the acceleration request. By injecting hydrogen gas and natural gas from the direct injection valves 18A and 18B for hydrogen and CNG so that the combustion air-fuel ratio in the 10 combustion chambers becomes the lean air-fuel ratio (λ = 1.9), exhaust gas Unburned gas accumulation control for accumulating unburned gas on the upstream side of the turbine 85b in the passage 15 is executed. Similar to the unburned gas accumulation control of the second embodiment, in the unburned gas accumulation control of the present embodiment, the injection amount of hydrogen gas and natural gas is changed from substantially the same volume ratio, and the injection amount of hydrogen gas is changed. And increase the volume ratio of the natural gas injection amount (the larger the required acceleration, the higher the volume ratio of the natural gas injection amount). Similarly to the second embodiment, the control unit 100 drives the engine 10 by the generator 20 so as to maintain the rotational speed of the engine 10 at 2000 rpm during unburned gas accumulation control.

  The predetermined period is as short as possible so that the unburned gas can be accumulated upstream of the turbine 85b in the exhaust passage 15 by an amount capable of rotating the turbine 85b vigorously by the combustion of the unburned gas. .

  The control unit 100 then performs the direct injection valve 18A for hydrogen and CNG so that the combustion air-fuel ratio in the combustion chamber becomes the lean air-fuel ratio (λ = 1.9) after execution of the unburned gas accumulation control. , 18B, hydrogen gas and natural gas are respectively injected to restart ignition. When the high-temperature gas combusted in the combustion chamber by this re-ignition is exhausted into the exhaust passage 15, unburned gas accumulated on the upstream side of the turbine 85 b in the exhaust passage 15 is combusted at once by the exhaust gas. As a result, when the vehicle 1 is requested to accelerate more than a predetermined amount during heating operation control (light load operation), a high supercharging pressure can be obtained immediately.

  The control by the controller 100 will be specifically described based on the flowchart of FIG.

  In steps S61 to S65, processing operations similar to those in S31 to S35 of the second embodiment are performed.

  In step S66 following step S65, it is determined whether there is no power generation request and only a heating request is made. When the determination in step S66 is YES, the process proceeds to step S67, while when the determination in step S66 is NO, the process proceeds to step S70.

  In the step S67, the heating operation control is executed, and in the next step S68, it is determined whether or not there is an acceleration request greater than or equal to a predetermined value for the vehicle 1. When the determination in step S68 is NO, the process proceeds to step S75. On the other hand, when the determination in step S68 is YES, the process proceeds to step S69, and the unburned gas accumulation control is executed. After step S69, the process proceeds to step S70.

  In step S70, it is determined whether the required output of the drive motor 40 is smaller than a predetermined value (the same value as the predetermined value in the first embodiment (step S11)), and the determination in step S70 is NO. In some cases, the process proceeds to step S71, where the target rotational speed of the engine 10 is set to a higher value as the required output of the drive motor 40 is larger, and is set to a target boost pressure corresponding to the required output of the drive motor 40. At this time, the injection amounts of hydrogen gas and natural gas are set to substantially the same volume ratio (both are about 50%), and the combustion air-fuel ratio in the combustion chamber is set to the lean air-fuel ratio (λ = 1.9). When the process proceeds from step S69 to step S70, the determination in step S70 is NO, and the process proceeds to step S71. After step S71, the process proceeds to step S75.

  When the determination in step S70 is YES, the process proceeds to step S73. In step S73, the target rotational speed of the engine 10 is set to 2000 rpm, and the target boost pressure corresponding to the required output of the drive motor 40 is set. Also at this time, the injection amounts of hydrogen gas and natural gas are set to substantially the same volume ratio (both are about 50%), and the combustion air-fuel ratio in the combustion chamber is set to the lean air-fuel ratio (λ = 1.9). In step S73, the engine 10 is steadily operated.

  In the next step S74, it is determined whether or not the NOx occlusion amount of the NOx occlusion reduction catalyst 82 is equal to or greater than a predetermined amount (the same value as the predetermined amount in the second embodiment (step S39)). If the determination in step S74 is no, the process proceeds to step S75. In step S75, signals from various sensors are newly read to check whether or not there is a new engine request operation, and it is determined whether or not there is no operation request for the engine 10. When the determination in step S75 is NO, the process returns to step S66. On the other hand, when the determination in step S75 is YES, the process proceeds to step S76, the engine 10 is stopped, and then the process returns.

  When the determination in step S74 is YES, the process proceeds to step S77 to execute NOx release control, and in the next step S78, whether NOx release is completed (whether t1 time has elapsed from the start of NOx release). ). When the determination at step S78 is NO, the processing operation at step S78 is repeated, while when the determination at step S78 is YES, the process proceeds to step S75.

  Therefore, in the present embodiment, when the vehicle 1 is requested to accelerate more than a predetermined value during heating operation control (during light load operation), the engine 10 is kept in a state where ignition is stopped for a predetermined period from the acceleration request time. By injecting hydrogen gas and natural gas from the hydrogen and CNG direct injection valves 18A and 18B, respectively, so that the combustion air-fuel ratio in the combustion chamber becomes the lean air-fuel ratio (λ = 1.9), the exhaust passage 15, an unburned gas accumulation control for accumulating unburned gas on the upstream side of the turbine 85 b is executed. After the unburned gas accumulation control is executed, the combustion air-fuel ratio in the combustion chamber becomes the lean air-fuel ratio (λ = 1. 9) Since hydrogen gas and natural gas are respectively injected from the hydrogen and CNG direct injection valves 18A and 18B so as to restart ignition, the ignition of the vehicle 1 during light load operation is performed. When the acceleration request exceeds a predetermined value, a high supercharging pressure can be obtained as early as possible.

  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 each of the above embodiments, the engine 10 is a power generation engine that is used to generate power by driving the generator 20 in a series hybrid system. However, in the first embodiment, the engine 10 is the same as that of the vehicle 1. It is also possible to use an engine (including a parallel hybrid system engine) that drives the drive wheels 61. In this case, for example, when the vehicle 1 is requested to accelerate more than a predetermined speed when idling is stopped at a predetermined vehicle speed or lower, the unburned gas accumulation control as in the first embodiment may be executed to start the engine 10. .

  In each of the above embodiments, the engine 10 is a rotary piston engine, but it is also possible to use a reciprocating engine.

  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 is useful for a control device for a multi-fuel engine mounted on a vehicle and configured to be able to supply a first fuel and a second fuel, respectively.

DESCRIPTION OF SYMBOLS 1 Vehicle 10 Multifuel engine 14 Intake passage 15 Exhaust passage 18A Hydrogen direct injection valve (1st fuel injection valve)
18B CNG direct injection valve (second fuel injection valve)
20 Generator (motor that starts the engine)
82 NOx storage reduction catalyst 85 Exhaust turbocharger 85a Compressor 85b Turbine 100 Control unit (control means)

Claims (8)

A control device for a multi-fuel engine mounted on a vehicle,
The above engine
A first fuel injection valve for directly injecting a first fuel made of hydrogen into the combustion chamber of the engine;
In the combustion chamber of the engine, a gaseous fuel having a high calorific value per unit volume with respect to the first fuel, a low NOx emission amount from the engine under the same combustion air-fuel ratio, and a low lean-limit combustion air-fuel ratio A second fuel injection valve for directly injecting a second fuel comprising:
A supercharger for supercharging intake air into the combustion chamber of the engine,
Have
Control means for controlling the operation of the engine including the operation of the first and second fuel injection valves;
The control means injects the first and second fuels into the combustion chamber of the engine at substantially the same volume ratio, and the combustion air-fuel ratio in the combustion chamber is determined based on the NOx emission amount from the engine. The first and second fuel injection valves are controlled so that the lean air-fuel ratio becomes substantially the same as the NOx emission amount when only two fuels are burned with the lean air-fuel ratio. A control device for a multi-fuel engine. The control apparatus for a multi-fuel engine according to claim 1,
The engine is a power generation engine used to drive a generator in a series hybrid system to generate power,
The control means is configured to operate at a medium load or a high load that is a load greater than or equal to a predetermined load and in a predetermined rotation speed region when the engine is in a steady operation at the time of a power generation request. Multi-fuel engine control device. The control apparatus for a multi-fuel engine according to claim 1 or 2,
The supercharger is an exhaust turbocharger having a turbine disposed in an exhaust passage of the engine and a compressor disposed in an intake passage of the engine and coupled to the turbine.
When the engine is started due to the establishment of a predetermined condition when the engine is stopped, the combustion air-fuel ratio in the combustion chamber is reduced to the lean air during a predetermined period from the start of the engine to before ignition. Unburnt gas accumulation that causes unburned gas to accumulate on the upstream side of the turbine in the exhaust passage by injecting the first and second fuels from the first and second fuel injection valves so that the fuel ratio becomes equal to the fuel ratio. Control, and after execution of the unburned gas accumulation control, the first and second fuels are supplied from the first and second fuel injection valves so that the combustion air-fuel ratio in the combustion chamber becomes the lean air-fuel ratio. A control device for a multi-fuel engine, characterized in that each of them is configured to inject and ignite. The control apparatus for a multi-fuel engine according to claim 3,
The multi-fuel engine is characterized in that the control means is configured to execute the unburned gas accumulation control when the engine is started when the vehicle is requested to accelerate more than a predetermined value as the predetermined condition. Control device. The control apparatus for a multi-fuel engine according to claim 3 or 4,
A motor for starting the engine;
The control means further controls the motor, and at the time of starting the engine when the predetermined condition is satisfied, the rotational speed of the engine driven by the motor is set when the predetermined condition is not satisfied. A control apparatus for a multi-fuel engine, characterized by being configured to be higher than that at the time of starting the engine. The control apparatus for a multi-fuel engine according to claim 2,
The supercharger is an exhaust turbocharger having a turbine disposed in an exhaust passage of the engine and a compressor disposed in an intake passage of the engine and coupled to the turbine.
The engine further includes a NOx occlusion reduction catalyst that is disposed downstream of the turbine in the exhaust passage and purifies the 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 the occluded NOx in a rich air-fuel ratio atmosphere,
When the NOx is released from the NOx storage reduction catalyst, the control means sets the engine to no-load operation, sets the combustion air-fuel ratio in the combustion chamber of the engine to a rich air-fuel ratio, and completes NOx release from the start of NOx release. If the vehicle has requested acceleration more than a predetermined time before a predetermined time, the combustion air-fuel ratio in the combustion chamber is rich when the ignition is stopped from the predetermined time before the completion of NOx release. Unburned gas that accumulates unburned gas on the upstream side of the turbine in the exhaust passage by injecting the first and second fuels from the first and second fuel injection valves so that the air-fuel ratio is obtained. The accumulation control is executed, and after the unburned gas accumulation control is executed, the first and second fuel injection valves adjust the combustion air-fuel ratio in the combustion chamber to the lean air-fuel ratio. Control device for a multi-fuel engine, characterized in that the serial first and second fuel are arranged to resume the ignition by injection, respectively. The control apparatus for a multi-fuel engine according to claim 2,
The supercharger is an exhaust turbocharger having a turbine disposed in an exhaust passage of the engine and a compressor disposed in an intake passage of the engine and coupled to the turbine.
A heating device for heating the vehicle interior of the vehicle using the cooling water of the engine;
The control means operates the engine at a light load that is a load smaller than the predetermined load at the time of a heating request without a power generation request, and at the time of the light load operation, the vehicle has been requested to accelerate more than a predetermined amount. Sometimes, the first and second fuel injection valves cause the combustion air-fuel ratio in the combustion chamber to become the lean air-fuel ratio in a state where ignition is stopped for a predetermined period after the acceleration request. Two fuels are respectively injected to execute unburned gas accumulation control for accumulating unburned gas upstream of the turbine in the exhaust passage, and after execution of the unburned gas accumulation control, the combustion air in the combustion chamber is The first and second fuel injection valves are respectively injected from the first and second fuel injection valves so that the fuel ratio becomes the lean air-fuel ratio, and the ignition is restarted. The control device of the multi-fuel engine. In the control apparatus of the multi-fuel engine as described in any one of Claims 3-7,
The control means reduces the volume ratio of the first fuel injection amount by changing the injection amounts of the first and second fuels from substantially the same volume ratio during execution of the unburned gas accumulation control. And a controller for a multi-fuel engine, characterized in that the volume ratio of the injection amount of the second fuel is increased.

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