JP6225840B2 - Fuel injection control device for gaseous fuel engine - Google Patents

Description

  The present invention belongs to a technical field related to a fuel injection control device for a gaseous fuel engine mounted on a vehicle.

  Conventionally, for example, as shown in Patent Document 1, an engine that uses gaseous fuel such as hydrogen is known. In Patent Document 1, first fuel injection that injects gaseous fuel into an intake passage of the engine is known. A valve and a second fuel injection valve for directly injecting gaseous fuel into the combustion chamber of the engine are provided. In the exhaust passage of the engine, a catalyst such as a NOx storage reduction catalyst for purifying exhaust gas of the engine is disposed.

  Further, for example, in Patent Document 2, in a heating control apparatus for a hybrid vehicle that performs heating of a vehicle interior using engine coolant, when the coolant temperature of the engine is lower than a predetermined water temperature set in advance, The engine operating point is changed from the operating point on the maximum efficiency control line to the operating point on the heating control line along the constant power curve (on the low load side and the high rotation side with respect to the operating point on the maximum efficiency control line). It is disclosed to move to a driving point).

JP 2009-228445 A JP-A-10-203145

  By the way, when the catalyst disposed in the exhaust passage of the engine is in an inactive state and the catalyst is to be activated, the engine operating point is maintained at the engine output as in Patent Document 2 described above. However, it is conceivable to move to an operation point on the low load side and the high rotation side. That is, when the engine is operated at a high speed, the flow rate of the exhaust gas increases, so that the amount of heat released in the exhaust passage from the exhaust opening of the combustion chamber to the catalyst decreases, and the exhaust gas vigorously increases. Since it contacts with a catalyst, it becomes easy to activate a catalyst. If the engine is moved to an operating point where the efficiency of the engine is lowered, the amount of waste heat is increased and the temperature of the exhaust gas is increased, so that the catalyst is more easily activated.

  However, in Patent Document 2, in order to reduce the engine load (output torque), it is necessary to reduce the intake air amount by reducing the opening of the throttle valve, which increases the pumping loss. Therefore, deterioration of fuel consumption due to this becomes a problem.

  The present invention has been made in view of such points, and an object of the present invention is to improve fuel efficiency by reducing the opening of the throttle valve when the catalyst is activated by increasing the flow rate of the exhaust gas of the engine. An object of the present invention is to enable the operation point of the engine to be moved to an operation point on the high rotation side without causing deterioration and without changing the engine output.

In order to achieve the above object, in the present invention, a first fuel injection valve for injecting gaseous fuel into the intake passage of the engine for a fuel injection control device of a gaseous fuel engine mounted on a vehicle, A second fuel injection valve that directly injects gaseous fuel into the combustion chamber of the engine and an upstream side of the first fuel injection valve in the intake passage are arranged to adjust the amount of intake air into the combustion chamber. A throttle valve, a catalyst disposed in the exhaust passage of the engine, for purifying the exhaust gas of the engine, and a catalyst active / inactive detecting means for detecting whether the catalyst is in an active state or an inactive state And control means for controlling the operation of the first fuel injection valve, the second fuel injection valve and the throttle valve, wherein the control means is in an inactive state of the catalyst by the catalyst activity / inactivity detection means. detection The total fuel injection by the first fuel injection valve and the second fuel injection valve while maintaining the opening degree of the throttle valve and the combustion air-fuel ratio in the combustion chamber when the active state of the catalyst is detected. Catalyst activation control for reducing the intake air amount by increasing the ratio of the fuel injection amount by the first fuel injection valve to the amount and moving the engine operating point to the high rotation side so that the engine output is maintained Further, the control means is configured to inject gaseous fuel by the second fuel injection valve after the intake opening that opens to the combustion chamber of the engine is closed. It was configured to be.

  With the above configuration, the ratio of the fuel injection amount (fuel injection amount to the intake passage) by the first fuel injection valve with respect to the total fuel injection amount increases into the combustion chamber without reducing the throttle valve opening. The amount of intake air can be reduced. As a result, the output torque of the engine is reduced, but the engine output is maintained by moving the operating point of the engine to the high rotation side. Therefore, the operating point of the engine can be moved to the operating point on the high speed side without changing the engine output without causing deterioration in fuel consumption due to the throttle valve opening being reduced.

  In one embodiment of the fuel injection control device for the gaseous fuel engine, the gaseous fuel is hydrogen, the catalyst is a NOx storage reduction catalyst, and the NOx storage reduction catalyst converts NOx in the exhaust gas of the engine. The NOx occluded in a lean air-fuel ratio atmosphere and the occluded NOx in a rich air-fuel ratio atmosphere and an atmosphere in which the temperature of the NOx occlusion reduction catalyst is higher than a predetermined temperature higher than the activation temperature of the NOx occlusion reduction catalyst. And a NOx occlusion amount detection means for detecting the NOx occlusion amount of the NOx occlusion reduction catalyst, and a catalyst temperature detection means for detecting the temperature of the NOx occlusion reduction catalyst, wherein the control means comprises: The NOx occlusion amount by the NOx occlusion amount detection means is less than the first predetermined amount when the catalytic activity / inactivity detection means detects the catalyst active state. If the engine is in a lean condition, the NOx storage / reduction catalyst stores NOx and the NOx emission amount from the combustion chamber is less than a preset amount. The operation of the injection valve, the second fuel injection valve, and the throttle valve is controlled, and the NOx occlusion amount of the NOx occlusion reduction catalyst is greater than or equal to the first predetermined amount when the active state of the catalyst is detected, and the catalyst When the temperature of the catalyst by the temperature detecting means is equal to or higher than the predetermined temperature, the first fuel injection valve is configured to make the engine perform a rich operation in which the NOx occlusion reduction catalyst releases the occluded NOx, It is configured to control the operation of the second fuel injection valve and the throttle valve, and the control means further comprises an inactive state of the catalyst by the catalytic activity / inactivity detecting means. The catalyst activation control is executed when the state is detected and when the NOx occlusion amount by the NOx occlusion amount detection means is equal to or larger than a second predetermined amount smaller than the first predetermined amount. .

  Thus, before the NOx occlusion amount reaches the first predetermined amount in the NOx occlusion reduction catalyst, the catalyst activation control is executed to activate the NOx occlusion reduction catalyst, and the temperature of the NOx occlusion reduction catalyst exceeds the predetermined temperature. As a result, if the NOx occlusion amount reaches the first predetermined amount, the NOx release condition has already been established, and NOx can be released immediately. The second predetermined amount is as close as possible to the first predetermined amount, and the NOx occlusion amount is made to be the first predetermined amount by executing the catalyst activation control from the time when the NOx occlusion amount becomes the second predetermined amount. The amount of NOx occlusion reduction catalyst may be set to an amount that allows the temperature of the NOx occlusion reduction catalyst to be equal to or higher than a predetermined temperature. In this way, by executing the catalyst activation control only when the NOx occlusion amount becomes close to the amount (first predetermined amount) at which NOx must be released, the engine rotation for catalyst activation is performed. The rise can be suppressed as much as possible.

  As described above, when the control means detects the inactive state of the catalyst by the catalyst activity / inactivity detection means, the NOx occlusion amount by the NOx occlusion amount detection means is not less than the second predetermined amount. In some cases, when configured to execute the catalyst activation control, the vehicle further includes vehicle stop detection means for detecting stop of the vehicle, and the control means stops the vehicle by the vehicle stop detection means. At the time of detection, it is preferable that the catalyst activation control is not executed even when the inactive state of the catalyst is detected and the NOx occlusion amount is not less than the second predetermined amount.

  By doing so, it is possible to prevent the driver of the vehicle from feeling uncomfortable due to an increase in engine rotation while the vehicle is stopped.

  Further, when the control means detects the inactive state of the catalyst by the catalyst activity / inactivity detection means, and when the NOx occlusion amount by the NOx occlusion amount detection means is equal to or greater than the second predetermined amount, In the case where the catalyst activation control is configured to be executed, the control means, when the engine is in the rich operation, the first fuel injection valve and the engine It is preferable that the ratio of the fuel injection amount by the first fuel injection valve to the total fuel injection amount by the second fuel injection valve is increased.

  As a result, by increasing the ratio of the fuel injection amount by the first fuel injection valve to the total fuel injection amount, it is possible to reduce the intake amount into the combustion chamber and perform the rich operation. As a result, the rich operation is performed. Also, the engine output similar to that during lean operation can be maintained, and NOx can be released at an efficient operation point similar to that during lean operation.

In another embodiment of the fuel injection control device of the gaseous fuel engine, the vehicle includes a generator that is driven by the engine to generate electric power, a battery that stores electric power generated by the generator, the generator, And a drive motor driven by electric power supplied from at least one of the batteries. The hybrid vehicle is driven by the drive motor.

  As described above, according to the fuel injection control device for a gaseous fuel engine of the present invention, when the inactive state of the catalyst is detected, the opening degree of the throttle valve and the combustion in the combustion chamber of the engine are compared with the detected state of the catalyst. While increasing the ratio of the fuel injection amount by the first fuel injection valve to the total fuel injection amount by the first fuel injection valve and the second fuel injection valve while maintaining the air-fuel ratio, By performing catalyst activation control that moves the operating point of the engine to the high speed side so that the engine output is maintained, the engine does not deteriorate due to the throttle valve opening being reduced. The operating point of the engine can be moved to the operating point on the high speed side without changing the output.

1 is a schematic view of a vehicle equipped with a fuel injection control device for a gaseous fuel engine according to an embodiment of the present invention. It is a block diagram which shows the structure of the engine of the said vehicle, and its control system. It is a flowchart which shows the first half part of the processing operation at the time of the engine driving | operation by a control unit. It is a flowchart which shows the latter half part of the processing operation at the time of the engine driving | operation 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 view of a vehicle 1 equipped with a fuel injection control device for a gaseous fuel engine according to an embodiment of the present invention. The vehicle 1 is a so-called range extender EV vehicle (which can be said to be a series type hybrid vehicle in a broad sense), and includes an engine 10, a generator 20 driven by the engine 10 to generate electric power, and the generator The high-voltage and large-capacity battery 30 in which the power generated by the battery 20 is stored (charged), and both the generated power of the generator 20 driven by the engine 10 and the stored power (discharge power) of the battery 30 or And a drive motor 40 that is driven only by the discharge power of the battery 30 (in this embodiment, it is basically driven only by the discharge power of the battery 30 as will be described later). In the present embodiment, the engine 10 is started by a starter motor (not shown). However, the generator 20 may be changed to a motor generator, and the engine 10 may be started by driving the motor generator as a motor. Is possible.

  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. When 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 accelerated, the engine 10 is started. Thus, 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 used only for power generation by the generator 20. The engine 10 is a gaseous fuel engine. In this embodiment, the hydrogen gas stored in the hydrogen tank 70 is a hydrogen engine supplied as fuel.

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

  Each of the rotors 12 has apex seals (not shown) at the apexes of the triangles, and 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 the port injection valve 17 described later), a cross-sectional area (valve opening degree) of the intake passage 14 is driven by a throttle valve actuator 90 such as a stepping motor. A throttle valve 16 for adjustment 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).

  A port injection valve 17 (first fuel injection valve) that injects hydrogen gas supplied from the hydrogen tank 70 into the intake passage 14 is provided in each branch passage downstream of the branch portion of the intake passage 14. It is arranged. The hydrogen gas injected by the port injection valve 17 is mixed with air (premixed state) and supplied to the working chamber in the intake stroke.

  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 stored in a lean air-fuel ratio atmosphere, and the stored NOx is stored in the rich air-fuel ratio atmosphere and the temperature of the NOx storage-reduction catalyst 82 is the activity of the NOx storage-reduction catalyst 82. The NOx is released under an atmosphere at a predetermined temperature higher than the gasification temperature and is reduced to react with HC and CO in the exhaust gas to reduce.

  In each rotor housing 11 (each cylinder), a direct injection valve 18 (second cylinder) that directly injects hydrogen gas supplied from the hydrogen tank 70 into the working chamber (combustion chamber) in the compression stroke of the rotor accommodating chamber 11a. And two ignition plugs 19 for igniting the hydrogen gas injected from the port injection valve 17 and the direct injection valve 18.

  The mass ratio of the fuel injection amount by the port injection valve 17 to the total fuel injection amount by the port injection valve 17 and the direct injection valve 18 (hereinafter referred to as the port injection ratio) and the direct injection valve 18 by the total fuel injection amount The mass ratio of the fuel injection amount (hereinafter referred to as direct injection ratio) is determined in advance and is basically 50%, but these port injection ratio and direct injection ratio are as described below. Change.

  In the present embodiment, the intake opening is configured to be opened and closed by the rotor 12 and fully closed during the compression stroke (so-called intake late closing configuration). In such a configuration of slow intake closing, the output torque of the engine 10 decreases due to a decrease in the effective compression ratio, but a turbocharger 85 is provided in order to prevent the output torque from decreasing. Further, in the configuration of the intake air late closing, the hydrogen gas injected from the port injection valve 17 and the intake air are about to be returned from the working chamber to the intake passage 14 through the intake opening in the compression stroke. This can be prevented by the supercharging pressure by the supercharger 85.

  The turbocharger 85 includes a compressor 85 a disposed on the upstream 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. It is comprised with the arrange | positioned turbine 85b. 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 85 a in the intake passage 14.

  The vehicle 1 includes a battery current / voltage sensor 101 that detects a current flowing into and out of the battery 30 and a voltage of the battery 30, and an accelerator that detects an amount of depression of an accelerator pedal by a driver of the vehicle 1 (accelerator opening by a driver's operation). 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 Facing the formed water jacket (not shown), the water jacket An engine water temperature sensor 106 that detects the temperature of the engine cooling water flowing in the engine (engine water temperature), a tank pressure sensor 107 that detects the pressure in the hydrogen tank 70 (that is, the remaining amount of hydrogen gas in the hydrogen tank 70), and an intake passage. 14, an air flow sensor 108 for detecting the intake flow rate sucked into the engine 14, 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. A control unit 100 is provided. The rotational angle sensor 104 also serves as an engine rotational speed sensor that detects the rotational speed of the engine 10 (hereinafter referred to as engine rotational speed).

  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 includes, for example, a RAM and a ROM, and stores a program and data; 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.

  Based on the input signal, the control unit 100 outputs a control signal to the throttle valve actuator 90, the port injection valve 17, the direct injection valve 18, and the spark plug 19 to control the engine 10, and Control signals are 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 port injection valve 17, the direct injection valve 18 and the throttle valve 16.

  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, when the SOC of the battery 30 is higher than the predetermined capacity, the control unit 100 selects the one mode. Even if the SOC of the battery 30 is higher than the predetermined capacity, the control unit 100 opens the accelerator due to a driver's acceleration request or the like. When the required output of the drive motor 40 based on the signals from the degree sensor 102 and the vehicle speed sensor 103 is large, 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. The first mode is selected when the remaining amount of hydrogen gas in the hydrogen tank 70 by the tank pressure sensor 107 falls below a preset value.

  When the engine 10 is in a stopped state, the control unit 100 checks the presence or absence of a power generation request based on the required output of the drive motor 40 and the SOC value of the battery 30, and when there is a power generation request, the starter motor Then, the engine 10 is started, and the engine 10 is operated to cause the generator 20 to generate power.

  Below, the processing operation at the time of the driving | operation of the engine 10 by the control unit 100 is demonstrated based on the flowchart of FIG.3 and FIG.4.

  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, the presence or absence of a power generation request is confirmed based on the required output of the drive motor 40 and the SOC of the battery 30, and in the next step S4, it is determined whether or not there is a power generation request.

  When the determination in step S4 is NO, the process returns to step S1, while when the determination in step S4 is YES, the process proceeds to step S5 and the engine 10 is started.

  In the next step S6, it is determined whether or not the engine 10 has increased to a predetermined rotational speed (a rotational speed lower than a rotational speed (for example, 1800 rpm) within a predetermined rotational speed region described later) from the start, and this step S6. When the determination is NO, the routine proceeds to step S7, where the port injection ratio is made smaller than the first predetermined value, and the direct injection ratio is made larger than the second predetermined value (the direct injection ratio is changed to the port injection ratio). The sum of the ratio and the direct injection ratio is 100%). Thereby, a port injection ratio becomes smaller than 50% at the time of the below-mentioned normal power generation operation. Thereafter, the process returns to step S6.

  Here, at a low engine speed until the predetermined speed is reached, the supercharging pressure by the turbocharger 85 is low. Therefore, in the configuration of the intake air late closing as described above, the engine is injected from the port injection valve 17. The fuel and the sucked air are returned from the working chamber to the intake passage 14 through the intake opening in the compression stroke. On the other hand, the fuel injected from the direct injection valve 18 is injected after the intake opening is closed, and therefore is not returned to the intake passage 14. Therefore, at a low engine speed until the predetermined speed is reached when the engine 10 is started, the amount of fuel returned to the intake passage 14 is reduced by making the port injection ratio smaller than the first predetermined value, A reduction in the output of the engine 10 due to the return of fuel to the intake passage 14 is suppressed.

If the engine speed reaches the predetermined speed and the determination in step S6 is YES, the process proceeds to step S8 where the throttle valve 16 is fully opened and the combustion air-fuel ratio ( combustion chamber) in the working chamber (combustion chamber) is reached. Here, the total fuel injection amount is set so that the excess air ratio λ) is 2.3 (feedback controlled by the output of the air-fuel ratio sensor 105), and both the port injection ratio and the direct injection ratio are 50%. The engine speed Ne is set to 2000 rpm (the engine speed Ne may be any speed within a predetermined speed range including the maximum efficiency point of the engine 10 (within the speed range where the efficiency of the engine 10 is maximum or close to the maximum)). The engine 10 is operated at the operating point to cause the generator 20 to generate a predetermined amount of power. Hereinafter, the operation of the engine 10 in step S8 is referred to as a normal power generation operation. In this normal power generation operation, the fuel injected from the port injection valve 17 is not returned to the intake passage 14 due to the boost pressure by the turbocharger 85. In this embodiment, during the operation of the engine 10 (including the time of starting), the throttle valve 16 is always in the fully open state as in the normal power generation operation.

In the normal power generation operation, basically, the NOx storage reduction catalyst 82 is in the active state (the low temperature active three-way catalyst 81 is also in the active state), and the NOx storage amount of the NOx storage reduction catalyst 82 is the first place. This operation is performed when the amount is less than the fixed amount. In this operation, the NOx storage reduction catalyst 82 stores the NOx in the engine 10 and the amount of NOx discharged from the working chamber becomes equal to or less than a preset set amount. In order to achieve such a lean operation ( λ = 2.3), the operations of the port injection valve 17, the direct injection valve 18 and the throttle valve 16 are controlled. The first predetermined amount is an amount close to a level at which NOx can no longer be occluded, and is an amount that requires the occluded NOx to be released. 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. Therefore, the control unit 100 constitutes NOx occlusion amount detection means for detecting the NOx occlusion amount of the NOx occlusion reduction catalyst 82.

  In the next step S9, it is determined whether or not the engine water temperature by the engine water temperature sensor 106 is equal to or higher than a first predetermined temperature. The first predetermined temperature is a temperature corresponding to the temperature at which the NOx storage reduction catalyst 82 is activated. That is, in step S9, it is determined whether or not the NOx storage reduction catalyst 82 is in an active state, and the engine water temperature sensor 106 detects whether the NOx storage reduction catalyst is in an active state or an inactive state. Thus, the catalyst activity / inactivity detection means is configured.

  When the determination in step S9 is YES, the process proceeds to step S10, and it is determined whether or not the NOx occlusion amount of the NOx occlusion reduction catalyst 82 is smaller than the first predetermined amount. If the determination in step S9 is yes, the process directly returns. That is, the normal power generation operation is performed as it is.

  When the determination in step S9 is NO, the process proceeds to step S11, in which it is determined whether or not the NOx occlusion amount of the NOx occlusion reduction catalyst 82 is equal to or greater than a second predetermined amount that is less than the first predetermined amount. The second predetermined amount is a value as close as possible to the first predetermined amount, and the NOx occlusion amount is executed by performing catalyst activation control, which will be described later, when the NOx occlusion amount becomes the second predetermined amount. Before the first predetermined amount is reached, the engine water temperature is set to a second predetermined temperature higher than the first predetermined temperature (that is, the temperature of the NOx storage reduction catalyst 82 is set to the predetermined temperature or higher). Use as much as possible. The second predetermined temperature is a temperature corresponding to the predetermined temperature at which NOx can be released as the temperature of the NOx storage reduction catalyst 82. The engine water temperature sensor 106 also constitutes catalyst temperature detection means for detecting the temperature of the NOx storage reduction catalyst 82 in addition to the catalyst activity / inactivity detection means. As the catalyst temperature detecting means, a temperature sensor for detecting the temperature of the NOx storage reduction catalyst 82 may be provided in the NOx storage reduction catalyst 82 instead of the engine water temperature sensor 106. In this case, the temperature sensor is connected to the catalyst activity / It is also preferable to use as inactive detection means.

  If the determination in step S11 is NO, the process directly returns. That is, even when the inactive state of the NOx storage reduction catalyst 82 is detected, the normal power generation operation is performed when the NOx storage amount of the NOx storage reduction catalyst 82 is smaller than the second predetermined amount.

  On the other hand, when the determination in step S11 is YES, the process proceeds to step S12 to determine whether or not the vehicle 1 is stopped based on a signal from the vehicle speed sensor 103. The stop here is a vehicle speed that can be considered to be substantially stopped in addition to the vehicle speed being zero, and the vehicle driver feels uncomfortable due to an increase in engine rotation due to the execution of catalyst activation control described later. Including the case where the vehicle speed is such that The vehicle speed sensor 103 constitutes vehicle stop detection means for detecting the stop of the vehicle 1. Note that the determination in step S12 is not always necessary and can be eliminated.

  If the determination in step S12 is YES, the process returns as it is (performs the normal power generation operation). On the other hand, if the determination in step S12 is NO, the process proceeds to step S13, and port injection is performed for the normal power generation operation. The ratio is increased from 50% and the direct injection ratio is decreased from 50% (the sum of the port injection ratio and the direct injection ratio is 100%), and the operating point of the engine 10 is set to the normal power generation operation. Move to a higher rotation side, then return. That is, when the inactive state of the NOx occlusion reduction catalyst 82 is detected, and when the NOx occlusion amount of the NOx occlusion reduction catalyst 82 is equal to or greater than the second predetermined amount, the NOx occlusion reduction is performed while the vehicle 1 is stopped. When the active state of the catalyst 82 is detected, the intake amount is reduced and the engine output is maintained by increasing the port injection ratio while maintaining the opening degree of the throttle valve 16 and the combustion air-fuel ratio in the working chamber. Catalyst activation control for moving the operating point of the engine 1 to the high rotation side is executed. Thus, even if the opening degree of the throttle valve 16 is not reduced (even when the throttle valve 16 is fully opened), the intake amount into the working chamber can be reduced by increasing the port injection ratio. Thereby, although the output torque of the engine 10 becomes small, the engine output is maintained by the operating point of the engine 10 moving to the high rotation side. The engine speed after moving to the high speed side basically becomes a speed outside the predetermined speed range, and the efficiency of the engine 10 at this time is lower than that during the normal power generation operation. To do.

  When the determination in step S10 is NO, the process proceeds to step S14, and whether or not the engine water temperature by the engine water temperature sensor 106 is equal to or higher than the second predetermined temperature (that is, the temperature of the NOx storage reduction catalyst 82 is the predetermined temperature). Whether or not).

If the determination in step S14 is NO, the process returns as it is (performs the normal power generation operation). On the other hand, if the determination in step S14 is YES, the process proceeds to step S15, and the combustion air-fuel ratio (here, The total fuel injection amount is set so that the excess air ratio λ) becomes 0.9 (feedback control is performed by the output of the air-fuel ratio sensor 105), the port injection ratio is increased from 50%, and the direct injection ratio is set. The engine 10 is reduced at 50% (the sum of the port injection ratio and the direct injection ratio is 100%) and the engine 10 is operated at an operating point where the engine speed Ne is 2000 rpm (the same operating point as in the normal power generation operation). The generator 20 is operated to generate the predetermined amount of power. That is, when detecting the active state of the NOx storage reduction catalyst 82, when the NOx storage amount of the NOx storage reduction catalyst 82 is not less than the first predetermined amount and the temperature of the NOx storage reduction catalyst 82 is not less than the predetermined temperature, The operation of the port injection valve 17, the direct injection valve 18 and the throttle valve 16 is controlled so that the engine 10 is in a rich operation in which the NOx occlusion reduction catalyst 82 releases the occluded NOx. By increasing the port injection ratio as described above, it is possible to reduce the amount of intake into the working chamber and perform rich operation. As a result, even if rich operation is performed, the same engine output as in lean operation is maintained. It is possible to release NOx at an efficient operating point similar to that during lean operation.

  In the next step S16, it is determined whether or not a predetermined time has elapsed since the start of the rich operation. The predetermined time is a time required for releasing substantially the entire amount of NOx stored in the NOx storage reduction catalyst 82. If the determination in step S16 is NO, the operation in step S16 is repeated. If the determination in step S16 is YES, the process returns to step S8 (executes the normal power generation operation).

  Therefore, in this embodiment, when the inactive state of the NOx occlusion reduction catalyst 82 is detected, and when the NOx occlusion amount of the NOx occlusion reduction catalyst 82 is not less than the second predetermined amount, the vehicle 1 is stopped. In addition, when the activation state of the NOx storage reduction catalyst 82 is detected, the intake amount is reduced by increasing the port injection ratio while maintaining the opening degree of the throttle valve 16 and the combustion air-fuel ratio in the working chamber, and the engine output. By performing the catalyst activation control that moves the operating point of the engine 1 to the high rotation side so that the engine is maintained, the engine output can be reduced without deteriorating the fuel consumption due to the throttle opening of the throttle valve 16 being reduced. The operating point of the engine 10 can be moved to the operating point on the high rotation side without changing the engine. When the engine 10 is operated at a high speed in this way, the flow rate of the exhaust gas increases, so that the amount of heat radiation in the portion between the exhaust opening of the combustion chamber and the catalyst in the exhaust passage 15 decreases, and the exhaust gas. However, the NOx occlusion reduction catalyst 82 is vigorously contacted, so that the NOx occlusion reduction catalyst 82 is easily activated. Further, by moving to an operating point where the efficiency of the engine 10 becomes low, the amount of waste heat increases and the temperature of the exhaust gas also rises, making it easier to activate the NOx storage reduction catalyst 82.

  In the present embodiment, the catalyst activation control is executed only when the NOx occlusion amount of the NOx occlusion reduction catalyst 82 becomes close to the amount (first predetermined amount) at which NOx must be released. Thus, an increase in engine rotation for catalyst activation can be suppressed as much as possible.

  Further, while the vehicle 1 is stopped, the catalyst activation control is performed even when the inactive state of the NOx occlusion reduction catalyst 82 is detected and the NOx occlusion amount of the NOx occlusion reduction catalyst 82 is not less than the second predetermined amount. Since it is not executed, it is possible to prevent the driver of the vehicle 1 from feeling uncomfortable due to a change (rise) in engine rotation while the vehicle 1 is stopped.

  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 1 is a hydrogen rotary engine using hydrogen gas as a fuel. However, a reciprocating engine using hydrogen gas as a fuel may be used, and a gas other than hydrogen gas (for example, natural gas) may be used. A rotary engine or a reciprocating engine using (CNG)) as fuel may be used.

  Moreover, in the said embodiment, although the engine 1 and its fuel-injection control apparatus were mounted in the range extender EV vehicle (series type hybrid vehicle), not only this but any other provided with an engine and a vehicle drive motor It can also be mounted on a hybrid vehicle of such a type, or can be mounted on a vehicle driven only by an 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.

  INDUSTRIAL APPLICABILITY The present invention is useful for a fuel injection control device for a gaseous fuel engine mounted on a vehicle (particularly, a hybrid vehicle in which a catalyst for purifying engine exhaust gas is likely to become inactive).

DESCRIPTION OF SYMBOLS 1 Vehicle 10 Gaseous fuel engine 14 Intake passage 15 Exhaust passage 16 Throttle valve 17 Port injection valve (1st fuel injection valve)
18 Direct injection valve (second fuel injection valve)
82 NOx storage reduction catalyst 100 Control unit (control means) (NOx storage amount detection means)
103 vehicle speed sensor (vehicle stop detection means)
106 Engine water temperature sensor (catalytic activity / inactivity detection means) (catalyst temperature detection means)

Claims (5)

A fuel injection control device for a gaseous fuel engine mounted on a vehicle,
A first fuel injection valve for injecting gaseous fuel into the intake passage of the engine;
A second fuel injection valve for directly injecting gaseous fuel into the combustion chamber of the engine;
A throttle valve that is disposed upstream of the first fuel injection valve in the intake passage and adjusts the amount of intake air into the combustion chamber;
A catalyst disposed in an exhaust passage of the engine for purifying exhaust gas of the engine;
Catalytic activity / inactivity detecting means for detecting whether the catalyst is in an active state or in an inactive state;
Control means for controlling the operation of the first fuel injection valve, the second fuel injection valve and the throttle valve,
The control means maintains the opening degree of the throttle valve and the combustion air-fuel ratio in the combustion chamber when the catalyst inactive state is detected by the catalyst activity / inactivity detecting means with respect to the detection of the catalyst active state. However, by increasing the ratio of the fuel injection amount by the first fuel injection valve to the total fuel injection amount by the first fuel injection valve and the second fuel injection valve, the intake amount is reduced and the engine output is reduced. It is configured to perform catalyst activation control that moves the operating point of the engine to the high rotation side so as to be maintained ,
Further, the control means is configured to inject gaseous fuel by the second fuel injection valve after an intake opening that opens to the combustion chamber of the engine is closed . Fuel injection control device. The fuel injection control device for a gaseous fuel engine according to claim 1,
The gaseous fuel is hydrogen;
The catalyst is a NOx storage reduction catalyst,
The NOx occlusion reduction catalyst occludes NOx in the engine exhaust gas in a lean air-fuel ratio atmosphere, and stores the occluded NOx in a rich air-fuel ratio atmosphere and the temperature of the NOx occlusion reduction catalyst is the NOx occlusion catalyst. It is released under an atmosphere of a predetermined temperature or higher higher than the activation temperature of the reduction catalyst,
NOx occlusion amount detection means for detecting the NOx occlusion amount of the NOx occlusion reduction catalyst;
Catalyst temperature detecting means for detecting the temperature of the NOx storage reduction catalyst,
When the NOx occlusion amount by the NOx occlusion amount detection means is less than a first predetermined amount when the catalyst activation state is detected by the catalyst activity / inactivity detection means, the control means causes the engine to occlude the NOx occlusion. In order to achieve a lean operation in which the reduction catalyst stores NOx and the amount of NOx discharged from the combustion chamber is not more than a preset set amount, the first fuel injection valve, the second fuel injection valve, While controlling the operation of the throttle valve, the NOx occlusion amount of the NOx occlusion reduction catalyst is not less than the first predetermined amount and the temperature of the catalyst by the catalyst temperature detecting means is not less than When the temperature is equal to or higher than a predetermined temperature, the engine is operated in a rich manner such that the NOx storage reduction catalyst releases the stored NOx. A fuel injection valve is configured to control the operation of the second fuel injection valve and the throttle valve,
Further, the control means is a second predetermined amount when the inactive state of the catalyst is detected by the catalyst activity / inactivity detecting means and the NOx occlusion amount by the NOx occlusion amount detecting means is smaller than the first predetermined amount. When it is above, it is comprised so that the said catalyst activation control may be performed, The fuel-injection control apparatus of the gaseous fuel engine characterized by the above-mentioned. The fuel injection control device for a gaseous fuel engine according to claim 2,
Vehicle stop detection means for detecting the stop of the vehicle,
When the vehicle stop detection is detected by the vehicle stop detection means, the control means performs the catalyst activation control even when the inactive state of the catalyst is detected and the NOx occlusion amount is not less than the second predetermined amount. A fuel injection control device for a gaseous fuel engine, which is configured not to be executed. The fuel injection control device for a gaseous fuel engine according to claim 2 or 3,
When the engine is in the rich operation, the control means is configured so that the first fuel with respect to the total fuel injection amount by the first fuel injection valve and the second fuel injection valve is different from that in the lean operation. A fuel injection control device for a gaseous fuel engine, characterized by being configured to increase a ratio of a fuel injection amount by an injection valve. In the fuel-injection control apparatus of the gaseous fuel engine as described in any one of Claims 1-4,
The vehicle includes a generator that is driven by the engine to generate electric power, a battery that stores electric power generated by the generator, a drive motor that is driven by electric power supplied from at least one of the generator and the battery, and A fuel injection control device for a gaseous fuel engine, characterized in that the fuel injection control device is a hybrid vehicle driven by the drive motor.

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