JP6288017B2 - Multi-cylinder engine control device for hybrid vehicle - Google Patents

Description

  The present invention belongs to a technical field related to a multi-cylinder engine control apparatus for a hybrid vehicle.

  In general, in a multi-cylinder engine including a plurality of cylinders, the variation range of output torque between cylinders tends to be large particularly during light load operation. Invite. Further, for example, in Patent Document 1, in a hybrid vehicle, when the engine is operated at a light load, a rattling noise (rattle noise) is generated in the power distribution mechanism due to fluctuations in the output torque of the entire engine. In Patent Document 1, in order to suppress the generation of the rattling noise, the output torque of the entire engine is increased by, for example, executing an increase in the amount of power generated by the generator in a traveling region where there is a high possibility of the rattling noise. Increase processing is performed.

JP 2013-82356 A

  By the way, the hybrid vehicle is usually provided with a heating device (air conditioner) that heats the interior of the hybrid vehicle using the cooling water of the multi-cylinder engine as a heat source. When the hybrid vehicle is stopped, the remaining capacity (SOC) of the battery is high and there is no request for charging the battery, but when there is a request for heating of the passenger of the hybrid vehicle, the engine is operated and the passenger's It is conceivable to satisfy the heating requirement. In this case, it is sufficient for the engine to operate only at a light load. However, in order to suppress the generation of abnormal noise in the engine and the power distribution mechanism, the output torque of the entire engine is increased as in Patent Document 1 described above. It is possible. However, if the output torque of the entire engine is increased when the hybrid vehicle is stopped, fuel consumption is deteriorated.

  When the hybrid vehicle is stopped, if the remaining capacity (SOC) of the battery is low and there is a request to charge the battery, the battery is charged by generating power by operating the engine. When there is a battery charge restriction such as when the battery is cold, it is difficult to increase the power generation amount itself, and it is necessary to reduce the power generation amount by operating the engine at a light load.

  The present invention has been made in view of such a point, and the object of the present invention is that when the hybrid vehicle is stopped, there is no charge request to the battery and there is a passenger heating request, or to the battery. When there is a charge request for the battery and there is a charge restriction on the battery, the multi-cylinder engine can be operated at light load from the viewpoint of fuel consumption and charge restriction, and generation of abnormal noise in the multi-cylinder engine or the like can be suppressed. There is.

  In order to achieve the above object, in the present invention, a hybrid having a multi-cylinder engine including a plurality of cylinders, a generator driven by the engine to generate electric power, and a battery charged with electric power generated by the generator. Targeting a multi-cylinder engine control device for a vehicle, a stop detection means for detecting stop of the hybrid vehicle, a torque detection means for detecting output torque for each cylinder of the engine, and a temperature of cooling water of the engine are detected. An engine water temperature detecting means, a heating device for heating the interior of the hybrid vehicle by using cooling water of the engine as a heat source in response to a heating request from a passenger of the hybrid vehicle, and a control means for controlling the engine And the control means detects the stop of the hybrid vehicle by the stop detection means, The engine is configured to be operated at a light load equal to or lower than a predetermined load when there is no power request and there is a heating request from the occupant, or when there is a charge request to the battery and there is a charge restriction on the battery. The control means further includes a variation width of the output torque between the cylinders calculated from the output torque of each cylinder detected by the torque detection means during the light load operation of the engine while the hybrid vehicle is stopped. However, when the temperature of the cooling water detected by the engine water temperature detecting means is lower than a predetermined temperature when it becomes larger than a preset reference value, the output torque of the cylinder with the highest output torque is In order to match the output torque of the other cylinder, the first output torque adjustment control for adjusting the output torque of the other cylinder is executed, When the temperature of the cooling water detected by the engine water temperature detecting means is equal to or higher than the predetermined temperature, the output torque of the other cylinder is adjusted to match the output torque of the other cylinder with the output torque of the cylinder having the lowest output torque. The second output torque adjustment control is performed to adjust the output torque.

  With the above configuration, when the variation width of the output torque between the cylinders becomes larger than the reference value, the variation width of the output torque between the cylinders is reduced by executing the first or second output torque adjustment control. As a result, the generation of abnormal noise in the engine or the like can be suppressed without increasing the output torque of the entire engine. Thus, since it is not necessary to increase the output torque of the entire engine, it is possible to suppress the deterioration of fuel consumption and to reduce the amount of power generation and to cope with the battery charging limit. When the engine coolant temperature is lower than the predetermined temperature (that is, when the engine is cold), the engine output torque of the other cylinder is matched with the output torque of the cylinder with the highest output torque. It is possible to ensure the combustion stability when the engine is cold, and to promote warm-up of the engine. On the other hand, when the cooling water temperature of the engine is equal to or higher than the predetermined temperature, the fuel consumption can be improved as much as possible by combining the output torque of the other cylinder with the output torque of the cylinder having the lowest output torque.

  In the multi-cylinder engine control apparatus for a hybrid vehicle, the engine uses as a fuel a mixture of a first fuel and a second fuel having a high calorific value per unit volume with respect to the first fuel. In the second output torque adjustment control, the mixing ratio of the first fuel is increased with respect to the mixing ratio of the first fuel and the second fuel in the cylinder having the lowest output torque in the other cylinders. The mixing ratio of the first fuel and the second fuel in the other cylinder is the same as the mixing ratio of the first fuel and the second fuel in the cylinder having the lowest output torque, and It is preferable that the control is performed such that the combustion air-fuel ratio in the combustion chamber of the other cylinder is higher than the combustion air-fuel ratio in the combustion chamber of the cylinder having the lowest output torque.

  Accordingly, the output torque can be easily reduced in the cylinders other than the cylinder with the lowest output torque by the second output torque adjustment control, and the output torque of the cylinder with the lowest output torque can be reduced to other cylinders. The output torque of (cylinders other than the cylinder with the lowest output torque) can be easily matched.

  When the second output torque adjustment control is the control as described above, the first fuel is a fuel having higher ignitability than the second fuel, and the second output torque adjustment control is performed by the battery. During the light load operation of the engine when there is no charge request to the passenger and there is a heating request from the occupant, the mixing ratio of the first fuel and the second fuel in the cylinder having the lowest output torque in the other cylinders The first fuel in the other cylinders during light load operation of the engine when there is a charge request to the battery and there is a charge restriction on the battery. And the mixing ratio of the second fuel is the same as the mixing ratio of the first fuel and the second fuel in the cylinder having the lowest output torque, and the combustion air-fuel ratio in the combustion chamber in the other cylinder is set to A control in which the output torque is higher than the combustion air-fuel ratio in the combustion chamber of the lowest cylinder, it is preferable.

  That is, since the first fuel has high ignitability, combustion is performed at an early stage, and heat can easily escape to the engine coolant through the wall surface of the combustion chamber. From this, the temperature of the cooling water can be raised earlier by increasing the mixing ratio of the first fuel. Here, even when the second output torque adjustment control is executed, the temperature of the cooling water may be at or near a predetermined temperature. In this case, it is desirable to increase the temperature of the cooling water early. Therefore, during the light load operation of the engine when there is no charge request to the battery and there is a passenger heating request, the first fuel and the second fuel in the cylinder with the lowest output torque in the cylinders other than the cylinder with the lowest output torque. By increasing the mixing ratio of the first fuel with respect to the mixing ratio, the temperature of the engine cooling water can be quickly raised to a temperature suitable for heating. On the other hand, during the light load operation of the engine when there is a charge request to the battery and there is a charge limit of the battery, the mixing ratio of the first fuel and the second fuel in the cylinders other than the cylinder with the lowest output torque is calculated as the output torque. The same as the mixing ratio of the first fuel and the second fuel in the cylinder having the lowest output torque, and the combustion air-fuel ratio in the combustion chamber in the cylinder other than the cylinder having the lowest output torque is set to the combustion in the combustion chamber of the cylinder having the lowest output torque. By increasing the air-fuel ratio, fuel consumption and emissions can be improved.

  In the multi-cylinder engine control apparatus for a hybrid vehicle, the engine mixes, as fuel, a first fuel and a second fuel that has low ignitability and high calorific value per unit volume. The first output torque adjustment control is used for the first fuel and the second fuel in the cylinder having the highest output torque in the other cylinders. The mixing ratio is increased, and the combustion air-fuel ratio in the combustion chamber in the other cylinder is lowered relative to the combustion air-fuel ratio in the combustion chamber of the cylinder having the highest output torque, and the cooling by the engine water temperature detecting means is performed. It is preferable that the control is such that the amount of increase in the mixing ratio of the first fuel and the amount of decrease in the combustion air-fuel ratio are increased as the temperature of water is lower.

  Accordingly, the first output torque adjustment control can easily increase the output torque in the cylinders other than the cylinder having the highest output torque without causing misfire when the engine is cold. The output torque of other cylinders (cylinders other than the cylinder with the highest output torque) can be easily matched with the output torque of the highest cylinder.

  As described above, according to the multi-cylinder engine control device for a hybrid vehicle of the present invention, when the hybrid vehicle is stopped, there is no charge request for the battery and there is a passenger heating request, or the battery charge request. When there is a battery charge restriction and the multi-cylinder engine is operated at a light load, the deterioration of fuel consumption can be suppressed and the amount of power generation can be reduced to meet the battery charge restriction. Will be able to. In addition, when the engine is lightly operated while the hybrid vehicle is stopped, when the variation width of the output torque between the cylinders calculated from the output torque of each cylinder becomes larger than the reference value, the first or first By executing the output torque adjustment control 2, it is possible to reduce the variation width of the output torque between the cylinders and suppress the generation of noise in the engine or the like without increasing the output torque of the entire engine. it can. Further, when the engine coolant temperature is lower than the predetermined temperature, the output torque of the cylinder with the highest output torque is matched with the output torque of the other cylinders to ensure combustion stability when the engine is cold. And warming up the engine can be promoted. On the other hand, when the cooling water temperature of the engine is equal to or higher than the predetermined temperature, the fuel consumption can be improved as much as possible by combining the output torque of the other cylinder with the output torque of the cylinder having the lowest output torque.

1 is a schematic view of a hybrid vehicle equipped with a multi-cylinder engine control device according to an embodiment of the present invention. It is a block diagram which shows the structure of the multicylinder engine of the said hybrid vehicle, and its control system. It is a graph which shows the relationship between the excess air ratio (lambda) and NOx discharge | emission amount from an engine when making it burn with an engine about hydrogen gas, natural gas, and these mixed gas A, B, and C. FIG. Regarding hydrogen gas, natural gas, and mixed gas A, B, and C thereof, the relationship between the excess air ratio λ and the engine output torque and the excess air ratio λ and the thermal efficiency of the engine when the engine is burned It is a graph which shows a relationship. It is a flowchart which shows the processing 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 diagram of a hybrid vehicle 1 (hereinafter referred to as a vehicle 1) equipped with a multi-cylinder engine control apparatus according to an embodiment of the present invention. The vehicle 1 is a so-called range extender EV vehicle (also referred to as a series hybrid vehicle), and includes a multi-cylinder engine 10 (hereinafter referred to as an engine) including a plurality of cylinders (in this embodiment, two cylinders as will be described later). 10), a generator 20 that is driven by the engine 10 to generate power, a high-voltage, large-capacity battery 30 that stores (charges) the power generated by the generator 20, and the engine 10 And a drive motor 40 that is driven by at least one of the generated power of the generator 20 and the stored power (discharge power) of the battery 30. In the present embodiment, the generator 20 is a motor generator having a function of a motor, and the engine 10 is driven (cranked) by the generator 20 as a motor to start the engine 10. .

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

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

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

  The engine 10 is a power generation engine used to drive the generator 20 to generate power. The engine 10 is a multi-fuel engine configured such that hydrogen gas stored in the hydrogen tank 70 and natural gas (CNG) stored in the CNG tank 71 can be supplied as gaseous fuels. Hydrogen gas is equivalent to the first fuel, and natural gas is equivalent to the second fuel having lower ignitability and higher calorific value per unit volume than the first fuel. 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. The cross-sectional area (valve opening degree) of the intake passage 14 is adjusted by being driven by a throttle valve actuator 90 such as a stepping motor on the upstream side of the branch portion of the intake passage 14 (downstream side of an intercooler 86 described later). A throttle valve 16 is provided. The throttle valve 16 adjusts the amount of intake air into each rotor accommodating chamber 11a (the working chamber in the intake stroke). In the engine control described later in the present embodiment, the throttle valve 16 is fully opened except during light load operation.

  In each branch passage downstream of the branch portion of the intake passage 14, hydrogen gas from the hydrogen tank 70 and natural gas from the CNG tank 71 are supplied to the intake passage 14 (especially the intake port or its vicinity). A hydrogen port injection valve 17A (second fuel port injection valve) and a CNG port injection valve 17B (first fuel port injection valve), which are respectively injected, are disposed in the (preferably). 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 set in advance because the temperature of the cooling water of the engine 10 (hereinafter referred to as engine cooling water) is extremely low even when the engine 10 is extremely cold (even when the engine is cold). Used when starting at a temperature lower than the set temperature. In other cases, fuel (hydrogen gas and natural gas) is directly injected into the working chamber (combustion chamber) from hydrogen and CNG direct injection valves 18A and 18B described later. 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, the fuel is exceptionally injected from the hydrogen and CNG port injection valves 17A and 17B. In addition, when the engine 10 is started and operated, fuel is injected only by the hydrogen and CNG port injection valves 17A and 17B, or the hydrogen and CNG direct injection valves 18A and 18B and the hydrogen and CNG are injected. It is also possible to inject fuel through the port injection valves 17A and 17B. Conversely, the hydrogen and CNG port injection valves 17A and 17B can be eliminated. In the following description, it is assumed that fuel (hydrogen gas and natural gas) is injected by the hydrogen and CNG direct injection valves 18A and 18B.

  Two exhaust passages 15 are provided on the upstream side so as to communicate with the respective rotor accommodating chambers 11a, but are joined together on the downstream side. A low temperature active three-way catalyst 81 and a NOx occlusion reduction catalyst 82 for purifying exhaust gas are disposed downstream of the merging portion of the exhaust passage 15. The low temperature active three-way catalyst 81 is a three-way catalyst having a catalyst activation temperature lower than that of the NOx storage reduction catalyst 82, and is disposed upstream of the NOx storage reduction catalyst 82. In FIG. 2, arrows shown in the intake passage 14 and the exhaust passage 15 indicate the flow of intake and exhaust.

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

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

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

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

  The vehicle 1 is provided with a heating device that heats the passenger compartment of the vehicle 1 using engine coolant as a heat source in response to a heating request from a passenger of the vehicle 1. This heating device may be incorporated as an air conditioner. This heating device includes a heater core that exchanges heat between air blown into the passenger compartment and engine coolant, and a heating switch 55 (see FIG. 2) that is operated by a passenger of the vehicle 1 to operate the heating device. have.

  In addition, the vehicle 1 detects 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 a depression amount of an accelerator pedal by an occupant of the vehicle 1 (accelerator opening by an occupant's operation). An accelerator opening sensor 102 for detecting the vehicle speed, a vehicle speed sensor 103 for detecting the vehicle speed of the vehicle 1, a rotation angle sensor 104 provided on the eccentric shaft 13 for detecting the rotation angle position of the eccentric shaft 13, and a low temperature active sensor 3 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 original catalyst 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 water jacket (not shown) formed inside, the water jacket The engine coolant temperature sensor 106 (engine coolant temperature detection means) that detects the temperature of the engine coolant flowing through the engine (engine coolant temperature detection means), the pressure in the hydrogen tank 70 (that is, the remaining amount of hydrogen gas in the hydrogen tank 70), and the CNG tank 71 A tank pressure sensor 107 (provided separately for the hydrogen tank 70 and the CNG tank 71) for detecting the pressure (that is, the remaining amount of natural gas in the CNG tank 71) and the intake air flow rate drawn into the intake passage 14 An air flow sensor 108 that detects the temperature of the battery 30, a battery temperature sensor 109 that detects the temperature of the battery 30, the operation control of the engine 10, and the operation control of the first and second inverters 50 and 51 (that is, the generator 20 and the drive motor 40). And a control unit 100 that performs (operation control) and the like. The rotation angle sensor 104 also serves as an engine rotation speed sensor that detects the rotation speed of the engine 10. Further, the vehicle speed sensor 103 constitutes a stop detection unit that detects the stop of the vehicle 1.

  The control unit 100 is a controller based on a well-known microcomputer, and includes a central processing unit (CPU) that executes a program, a memory that is configured by, for example, a RAM or ROM, and stores a program and data, and an electrical signal An input / output (I / O) bus. The control unit 100 includes a battery current / voltage sensor 101, an accelerator opening sensor 102, a vehicle speed sensor 103, a rotation angle sensor 104, an air-fuel ratio sensor 105, an engine water temperature sensor 106, a tank pressure sensor 107, an air flow sensor 108, a battery temperature sensor. Various information signals from 109 etc. are input. The control unit 100 is input with a signal of operation information for the heating switch 55.

  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. Moreover, the control unit 100 detects the torque which acts on the rotating shaft (namely, eccentric shaft 6) of the said generator 20 based on the information of the said generated voltage and generated current. That is, when the operating state of the generator 20 is in the power generation state, the detected torque represents the output torque of the engine 10. In the present embodiment, the control unit 100 detects the output torque for each cylinder of the engine 10. That is, the output torque is detected at a predetermined rotational angle position of the eccentric shaft 13 by the rotational angle sensor 104. The predetermined rotation angle position is, for example, an ignition timing by the ignition plug 19 on the leading side or the trailing side of each cylinder or a timing close thereto. The timings of the two cylinders are shifted from each other by 180 ° in the rotational angle of the eccentric shaft 13, so that the output torque of one cylinder and the output torque of the other cylinder are converted every time the eccentric shaft 13 rotates 180 °. It will be detected alternately. Thus, the rotation angle sensor 104 and the control unit 100 constitute torque detecting means for detecting output torque for each cylinder of the engine 10.

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

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

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

  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 detected SOC of the battery 30 is lower than a first predetermined value (for example, 30%) in the battery running mode, the control unit 100 switches to the charging running mode while the charging running mode Sometimes, when the detected SOC of the battery 30 becomes higher than a second predetermined value (for example, 70%) set to a value higher than the first predetermined value, the battery driving mode is switched. Thereby, the SOC of battery 30 can be maintained within a preferable range that is neither too low nor too high.

  In the battery running mode, 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, the same as the presence or absence of a power generation request). If there is an operation request (power generation request) for the engine 10, the engine 10 is cranked by the generator 20 as a motor to start the engine 10, and after that start, the generator 20 generates power. Therefore, the engine 10 is operated. That is, when the SOC of the battery 30 is lower than the first predetermined value or the required output of the drive motor 40 exceeds the maximum dischargeable power of the battery 30 in the battery running mode. Sometimes, the engine 10 is operated on the assumption that there is a request for operating the engine 10.

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

  In the charging travel mode, the control unit 100 basically operates the engine 10 at a predetermined rotational speed, and the engine rotational speed during the engine steady operation (the predetermined rotational speed) is the highest efficiency point of the engine 10. Is a value in an efficient region including 1800 rpm to 2200 rpm, for example, 2000 rpm in this embodiment. The engine load during the engine steady operation is a medium load or a high load larger than a predetermined load. At this time, the battery 30 is charged and the drive motor 40 is driven with the power generated by the generator 20 that generates power by the output of the engine 10 (the remaining power obtained by subtracting the required output of the drive motor 40 from the generated power). Is charged to the battery 30). Further, when the required output of the drive motor 40 becomes larger than the engine output (generated power) at 2000 rpm as in the case of the acceleration request of the vehicle 1 or more during the steady engine operation, the shortage is reduced. It is supplemented by the discharge power of the battery 30 (not charged). However, if the required output of the drive motor 40 cannot be satisfied even if the discharge power of the battery 30 reaches the maximum dischargeable power of the battery 30, the engine speed is exceptionally made higher than the predetermined speed. .

  The operation of the engine 10 when the required output of the drive motor 40 exceeds the maximum dischargeable power of the battery 30 in the battery running mode is also a steady operation at the predetermined rotational speed (2000 rpm), and the discharge power of the battery 30 is reduced. It adjusts so that the required output of the drive motor 40 may be satisfied.

  The operation of the engine 10 (including the engine steady operation described above) when the light load operation as described later is not executed is a medium load operation or a high load operation.

  The control unit 100 controls the hydrogen direct injection valve 18A and the CNG direct injection valve 18B so as to supply hydrogen gas and natural gas to the engine 10 at a predetermined ratio in the medium load or high load operation. In the present embodiment, in the medium load or high load operation, hydrogen gas and natural gas are injected into the combustion chamber at substantially the same volume ratio (both 50%).

  In addition, the control unit 100 sets the combustion air-fuel ratio in the combustion chamber of the engine 10 to a predetermined air-fuel ratio during the medium load or high load operation. The predetermined air-fuel ratio is a lean air-fuel ratio, and the NOx emission amount from the engine 10 (combustion chamber) is, for example, the NOx emission amount when only natural gas is combusted with the lean combustion air-fuel ratio. The air-fuel ratio becomes substantially the same.

  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. .

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

  When the vehicle speed sensor 103 detects that the vehicle 1 has stopped, the control unit 100 has no charge request to the battery 30 and there is a heating request from the passenger of the vehicle 1 (that is, the heating switch 55 in the battery running mode). Is turned on), or when there is a charge request to the battery 30 and there is a charge restriction of the battery 30 (that is, when there is a charge restriction of the battery 30 in the charge travel mode), the engine 10 The engine 10 is operated assuming that there is an operation request. At this time, the engine 10 is operated at a light load equal to or less than the predetermined load. When the vehicle speed sensor 103 detects that the vehicle 1 has stopped, the control unit 100 operates the engine 10 at a medium load or high load operation when there is a charge request for the battery 30 and there is no charge restriction on the battery 30. When there is no request for charging the battery 30 and there is no request for heating by the passenger of the vehicle 1, the engine 10 is stopped. Hereinafter, the condition for operating the engine 10 at a light load as described above is referred to as a light load operation condition.

  Here, when the temperature of the battery 30 detected by the battery temperature sensor 109 is not within a predetermined range (for example, −10 ° C. to 60 ° C.), or the SOC of the battery 30 is slightly lower than the second predetermined value. If it is higher than the preset third predetermined value, the charging of the battery 30 is restricted from the viewpoint of suppressing the early deterioration of the battery 30, and the electric power that can be charged to the battery 30 at the time of this charging restriction is the engine power. This corresponds to a small amount of generated power at 10 light load operations. Therefore, when the vehicle 1 is stopped and the battery 30 is requested to be charged and the charging of the battery 30 is restricted, the engine 10 is operated at a light load. Further, when the vehicle 1 is stopped, when there is no request for charging the battery 30 and there is a heating request from the occupant of the vehicle 1, the engine 10 is lightly loaded from the viewpoint of suppressing deterioration of fuel consumption while satisfying the heating request of the occupant. drive.

  When the engine 10 is in a light load operation while the vehicle 1 is stopped, the control unit 100 varies the output torque variation between the cylinders calculated from the output torque of each cylinder (in this embodiment, the eccentric shafts 13 are mutually connected). When the difference between the output torque of one cylinder detected at a predetermined rotational angle position shifted by 180 ° and the output torque of the other cylinder is greater than a preset reference value, The first output torque adjustment control or the second output torque adjustment control is executed. The reference value is a value such that when the variation width becomes larger than the reference value, engine rotation is unstable and abnormal noise is generated in the engine 10.

  In the first output torque adjustment control, when the engine water temperature by the engine water temperature sensor 106 is lower than a predetermined temperature, the other output torque adjustment control is performed to match the output torque of the other cylinder with the output torque of the cylinder having the highest output torque. This is control for adjusting the output torque of the cylinder. The predetermined temperature is higher than the set temperature and lower than the temperature when the engine 10 is in a warm state. When the engine water temperature is lower than the predetermined temperature, it can be said that the engine 10 is in a cold state.

  In this embodiment, since there are two cylinders, the cylinder with the highest output torque is the cylinder with the higher output torque (hereinafter referred to as the high output torque cylinder) of the two cylinders, and the other cylinders described above. Is the cylinder with the lower output torque of the two cylinders (hereinafter referred to as the low output torque cylinder). By the first output torque adjustment control, the output torque of the low output torque cylinder is increased, and the difference between the output torque of the high output torque cylinder and the output torque of the low output torque cylinder is reduced.

  Specifically, in the first output torque adjustment control, in the low output torque cylinder, the mixing ratio of hydrogen gas is increased with respect to the mixing ratio (both 50%) of hydrogen gas and natural gas in the high output torque cylinder. In addition, the combustion air-fuel ratio in the combustion chamber of the low output torque cylinder is made lower than the combustion air-fuel ratio (λ = 1.9) in the combustion chamber of the high output torque cylinder, and the engine cooling by the engine water temperature sensor 106 is performed. In this control, the amount of increase in the mixing ratio of hydrogen gas and the amount of decrease in the combustion air-fuel ratio are increased as the water temperature is lower. That is, while increasing the mixing ratio of natural gas in the low output torque cylinder can easily increase the output torque of the low output torque cylinder, the natural ignitability is low when the engine 10 is cold. If the gas mixture ratio is increased, misfire may occur. Therefore, the output torque of the low output torque cylinder is increased by increasing the hydrogen gas mixture ratio with high ignitability and lowering the combustion air-fuel ratio.

  The second output torque adjustment control includes the output torque of the cylinder having the lowest output torque (low output torque cylinder in the present embodiment) when the engine water temperature by the engine water temperature sensor 106 is equal to or higher than the predetermined temperature. This is control for adjusting the output torque of the other cylinder (high output torque cylinder) in order to match the output torque of the other cylinder (high output torque cylinder).

  Specifically, in the second output torque adjustment control, in the high output torque cylinder, control for increasing the mixing ratio of hydrogen gas with respect to the mixing ratio of hydrogen gas and natural gas in the low output torque cylinder (hereinafter, Hydrogen gas ratio increase control), or the mixing ratio of hydrogen gas and natural gas in the high output torque cylinder is the same as the mixing ratio of hydrogen gas and natural gas in the low output torque cylinder, and In this control, the combustion air-fuel ratio in the combustion chamber in the high output torque cylinder is made higher than the combustion air-fuel ratio in the combustion chamber in the low output torque cylinder (hereinafter referred to as air-fuel ratio increase control). In the hydrogen gas ratio increase control, the combustion air-fuel ratio in the combustion chamber in the high-output torque cylinder may be the same as the combustion air-fuel ratio in the combustion chamber in the low-output torque cylinder, It may be higher than the combustion air-fuel ratio.

  In the present embodiment, the second output torque adjustment control is the hydrogen gas ratio increase control when the engine 10 is in a light load operation when there is no charge request to the battery 30 and there is a passenger heating request. The air-fuel ratio increase control is performed during light load operation of the engine 10 when the battery 30 is requested to be charged and the battery 30 is charged.

  That is, since hydrogen gas has high ignitability, combustion is performed at an early stage, and heat easily escapes to the engine coolant through the wall surface of the combustion chamber. For this reason, the engine water temperature can be raised earlier by increasing the mixing ratio of the hydrogen gas. Here, even when the second output torque adjustment control is executed, the engine water temperature may be at or near the predetermined temperature. In this case, it is desirable to increase the engine water temperature early. Therefore, the engine water temperature is adjusted to a temperature suitable for heating by executing the hydrogen gas ratio increase control during light load operation of the engine 10 when there is no charge request to the battery 30 and there is a passenger heating request. Will be able to rise early. On the other hand, at the time of a light load operation of the engine 10 when there is a charge request to the battery 30 and there is a charge restriction of the battery 30, the air-fuel ratio increase control is executed to improve fuel efficiency and emission.

  Next, the processing operation by the control unit 100 will be described based on the flowchart of FIG. Here, at the start of this flowchart, the battery running mode is set in a state where the engine 10 is stopped.

  In the first step S1, various input 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 / absence of an operation request for the engine 10 is confirmed based on the required output of the drive motor 40, the SOC of the battery 30, and the presence / absence of the light load operation condition. That is, when the SOC of the battery 30 is lower than the first predetermined value, when the requested output of the drive motor 40 exceeds the maximum dischargeable power of the battery 30, the vehicle speed sensor 103 detects the stop of the vehicle 1. When there is no charge request to the battery 30 and the heating switch 55 is on, or there is a charge request to the battery 30 and there is a charge restriction on the battery 30, there is an operation request for the engine 10 And

  In the next step S4, it is determined whether or not there is an operation request for the engine 10. 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 the light load operation condition is satisfied.

  When the determination in step S5 is NO, the process proceeds to step S6, the engine 10 is operated at a medium load or a high load, and then the process proceeds to step S15. On the other hand, when the determination in step S5 is YES, the process proceeds to step S7, the engine 10 is operated at a light load, and in the next step S8, the predetermined rotational angles of the eccentric shafts 13 shifted by 180 ° from each other by the rotation angle sensor 104. At the position, the output torques W1, W2 of each cylinder are detected.

  In the next step S9, the variation width of the output torque between the cylinders (that is, the difference between the output torque of one cylinder and the output torque of the other cylinder detected at positions 180 degrees apart from each other by the rotational angle of the eccentric shaft 13). It is determined whether (| W1-W2 |) is larger than a preset reference value Δ.

  If the determination in step S9 is NO, the process proceeds to step S15. If the determination in step S9 is YES, the process proceeds to step S10, and it is determined whether the engine water temperature is lower than the predetermined temperature.

  When the determination in step S10 is YES, the process proceeds to step S11 to execute the first output torque adjustment control, and then proceeds to step S15. On the other hand, when the determination in step S10 is NO, the process proceeds to step S12 to determine whether or not the heating switch 55 is on.

  When the determination in step S12 is YES, that is, when there is no charge request to the battery 30 and there is a heating request from the occupant, the light load operation condition is satisfied, the process proceeds to step S13, and the first The hydrogen gas ratio increase control in the output torque adjustment control 2 is executed, and then the process proceeds to step S15. On the other hand, when the determination in step S12 is NO, that is, when there is a charge request to the battery 30 and there is a charge restriction on the battery 30, the light load operation condition is satisfied, the process proceeds to step S14. The air-fuel ratio increase control in the second output torque adjustment control is executed, and then the process proceeds to step S15.

  In step S15, various input signals are newly read and the presence or absence of the engine requested operation is newly confirmed, and it is determined whether or not the operation request for the engine 10 is lost. When the determination in step S15 is NO, the process returns to step S5. On the other hand, when the determination in step S15 is YES, the process proceeds to step S16 to stop the engine 10 and then return.

  Therefore, in the present embodiment, when the vehicle 1 is stopped, there is no request for charging the battery 30 and there is a request for heating by the passenger of the vehicle 1, or there is a request for charging the battery 30 and the battery 30 is charged. When there is a limit, driving the engine 10 at a light load can suppress the deterioration of fuel consumption, and can reduce the amount of power generation and meet the charging limit of the battery 30.

  In addition, during the light load operation of the engine 10 while the vehicle 1 is stopped, the first or second output torque adjustment control is executed when the variation range of the output torque between the cylinders becomes larger than the reference value. Thus, it is possible to suppress the generation of noise in the engine 10 or the like without reducing the variation width of the output torque between the cylinders and increasing the output torque of the engine 10 as a whole.

  Further, when the temperature of the engine coolant is lower than the predetermined temperature, by executing the first output torque adjustment control, the output torque of the low output torque cylinder is matched with the output torque of the high output torque cylinder. Combustion stability during cold weather can be ensured and warm-up of the engine 10 can be promoted. On the other hand, when the temperature of the engine coolant is equal to or higher than the predetermined temperature, the fuel efficiency can be improved as much as possible by matching the output torque of the high output torque cylinder with the output torque of the low output torque cylinder.

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

  For example, in the above embodiment, the engine 10 is a power generation engine used to drive the generator 20 in a series hybrid vehicle to generate power. However, the engine 10 drives the driving wheels 61 of the parallel hybrid vehicle. In addition, an engine that drives the drive motor in a power generation state to charge the battery can be used.

  Moreover, in the said embodiment, although the engine 10 was used as the rotary piston engine, it can also be set as a reciprocating engine. Furthermore, the engine 10 is not limited to a two-cylinder engine, may be a multi-cylinder engine having three or more cylinders, and is not limited to a multi-fuel engine, but may be a single type of fuel (gas fuel may be used). Or an engine using only liquid fuel).

  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 multi-cylinder engine control device for a hybrid vehicle having a multi-cylinder engine including a plurality of cylinders, a generator driven by the engine to generate electric power, and a battery charged with electric power generated by the generator. It is.

DESCRIPTION OF SYMBOLS 1 Hybrid vehicle 10 Engine 20 Generator 30 Battery 55 Heating switch 100 Control unit (control means) (torque detection means)
103 Vehicle speed sensor (stop detection means)
104 Rotation angle sensor (torque detection means)
106 Engine water temperature sensor (engine water temperature detection means)

Claims (4)

A multi-cylinder engine control device for a hybrid vehicle having a multi-cylinder engine including a plurality of cylinders, a generator driven by the engine to generate electric power, and a battery charged with electric power generated by the generator,
Stop detection means for detecting stop of the hybrid vehicle;
Torque detecting means for detecting output torque for each cylinder of the engine;
Engine water temperature detecting means for detecting the temperature of the cooling water of the engine;
A heating device that heats the interior of the hybrid vehicle by using the cooling water of the engine as a heat source in response to a heating request from a passenger of the hybrid vehicle,
Control means for controlling the engine,
The control means detects the stop of the hybrid vehicle by the stop detection means, when there is no charge request for the battery and there is a request for heating of the occupant, or when a charge request for the battery is received. When there is a charging limit of the battery, the engine is configured to be operated at a light load equal to or lower than a predetermined load,
Further, the control means has a variation width of the output torque between the cylinders calculated from the output torque for each cylinder detected by the torque detection means during a light load operation of the engine while the hybrid vehicle is stopped. When it becomes larger than the preset reference value,
When the temperature of the cooling water detected by the engine water temperature detecting means is lower than a predetermined temperature, the output torque of the other cylinder is adjusted to match the output torque of the other cylinder with the output torque of the cylinder having the highest output torque. While executing the first output torque adjustment control to adjust the
When the temperature of the cooling water detected by the engine water temperature detecting means is equal to or higher than the predetermined temperature, the output of the other cylinder is adjusted to match the output torque of the other cylinder with the output torque of the cylinder having the lowest output torque. A multi-cylinder engine control device for a hybrid vehicle, wherein the second output torque adjustment control for adjusting torque is executed. The multi-cylinder engine control device for a hybrid vehicle according to claim 1,
The engine uses, as fuel, a first fuel and a second fuel having a high calorific value per unit volume with respect to the first fuel,
The second output torque adjustment control is a control for increasing the mixing ratio of the first fuel with respect to the mixing ratio of the first fuel and the second fuel in the cylinder having the lowest output torque in the other cylinders. Or the mixing ratio of the first fuel and the second fuel in the other cylinder is the same as the mixing ratio of the first fuel and the second fuel in the cylinder having the lowest output torque, and the other cylinder. The multi-cylinder engine control apparatus for a hybrid vehicle is characterized in that the combustion air-fuel ratio in the combustion chamber is higher than the combustion air-fuel ratio in the combustion chamber of the cylinder having the lowest output torque. The multi-cylinder engine control device for a hybrid vehicle according to claim 2,
The first fuel is a fuel having higher ignitability than the second fuel,
In the second output torque adjustment control, when the engine is in a light load operation when there is no charge request to the battery and there is a passenger heating request, the second output torque adjustment control is performed in the cylinder having the lowest output torque in the other cylinders. Light load on the engine when the mixing ratio of the first fuel is increased with respect to the mixing ratio of the first fuel and the second fuel, and when there is a charge request to the battery and there is a charge limitation of the battery During operation, the mixing ratio of the first fuel and the second fuel in the other cylinder is the same as the mixing ratio of the first fuel and the second fuel in the cylinder having the lowest output torque, and in the other cylinder A multi-cylinder of a hybrid vehicle characterized by controlling the combustion air-fuel ratio in the combustion chamber to be higher than the combustion air-fuel ratio in the combustion chamber of the cylinder having the lowest output torque Engine control unit. The multi-cylinder engine control device for a hybrid vehicle according to any one of claims 1 to 3,
The engine uses, as a fuel, a first fuel and a second fuel having a low ignitability and a high calorific value per unit volume with respect to the first fuel.
The first output torque adjustment control increases the mixing ratio of the first fuel with respect to the mixing ratio of the first fuel and the second fuel in the cylinder having the highest output torque in the other cylinders, and The combustion air-fuel ratio in the combustion chamber in the other cylinder is made lower than the combustion air-fuel ratio in the combustion chamber of the cylinder having the highest output torque, and the lower the temperature of the cooling water by the engine water temperature detection means, A multi-cylinder engine control apparatus for a hybrid vehicle, characterized in that the control is to increase the amount of increase in the mixing ratio of the first fuel and the amount of decrease in the combustion air-fuel ratio.

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