JP2011047282A - Control device of hydrogen engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain an element crack by flooding, without arranging a plurality of air-fuel ratio sensors and a cover, in a control device of a hydrogen engine having the air-fuel ratio sensor on the catalyst upstream side of an exhaust system. <P>SOLUTION: This control device of the hydrogen engine 5 includes a liner air-fuel ratio sensor 53 having a heater 53b on the upstream side of a three-way catalyst 51 of an exhaust passage 39, and uses hydrogen as fuel. A PCM 3 sets the target air-fuel ratio to the lean air-fuel ratio when the engine water temperature Tw detected by a water temperature sensor 59 is lower than the first reference temperature Tw1, and sets the target air-fuel ratio in the theoretical air-fuel ratio or the rich air-fuel ratio when the engine water temperature Tw is not lower than the first reference temperature Tw1 and lower than the second reference temperature Tw2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device for a hydrogen engine using hydrogen as a fuel, provided with an air-fuel ratio sensor having an element heating heater on the upstream side of a catalyst in an exhaust system.

  Conventionally, an air-fuel ratio sensor that detects an oxygen concentration in exhaust gas is provided in the exhaust passage, and feedback control of the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber is performed based on the output of the air-fuel ratio sensor. ing. This type of air-fuel ratio sensor has an element that outputs an electromotive force according to the oxygen concentration, and an element heating heater that heats the element. By energizing the element heating heater when the engine is started, Many devices activate the device quickly and ensure sufficient electromotive force.

  In addition, when the engine is started, the engine drive state is unstable, and it is required that the feedback control responsiveness be as good as possible to cope with it. However, the oxygen concentration was detected downstream of the catalyst. In this case, the air-fuel ratio sensor is often provided on the upstream side of the catalyst because the time lag becomes large and air-fuel ratio control with good response is difficult.

  However, a vehicle equipped with a hydrogen engine has the following problems when the air-fuel ratio sensor is provided on the upstream side of the catalyst. That is, in the hydrogen engine, a large amount of water is generated by the combustion of hydrogen, and there is a possibility that the element of the air-fuel ratio sensor is wetted by this water on the upstream side of the catalyst. When the heater is energized in such a state that the element is wet, the temperature of the wetted part is difficult to rise, so that the thermal stress of the element becomes non-uniform, the element is distorted, and the element is cracked. is there.

  In order to suppress the occurrence of such element cracking, for example, Patent Document 1 discloses a first air-fuel ratio sensor that is disposed upstream of the catalyst and has a heater, and a second air space that is disposed in the catalyst or downstream of the catalyst. An air-fuel ratio of a hydrogen engine that includes an air-fuel ratio sensor and restricts energization to the heater until the first air-fuel ratio sensor reaches a predetermined activation temperature and performs air-fuel ratio control based on the output of the second air-fuel ratio sensor A control device is disclosed.

  In addition, a structure in which a cover is provided so as to cover the element has been proposed in order to suppress the moisture of the element.

JP 2007-198158 A

  However, in the case of using a plurality of air-fuel ratio sensors as in the above-mentioned Patent Document 1, or in the case where a cover is provided so as to cover the element, as the number of parts increases, the number of assembly steps increases and the cost increases. There is a problem of doing.

  The present invention has been made in view of such points, and an object of the present invention is to provide a control apparatus for a hydrogen engine including an air-fuel ratio sensor having an element heating heater on the upstream side of a catalyst in an exhaust system. It is an object of the present invention to provide a technique for suppressing element cracking due to water exposure to an element without providing an air-fuel ratio sensor or a cover.

  In order to achieve the above object, the present invention controls the target air-fuel ratio so as to suppress the generation of moisture itself at the time of extreme cold, and at the time of cold at a higher temperature than at the time of extreme cold, Moisture generated by evaporation is evaporated.

  A first aspect of the present invention is a hydrogen engine control apparatus having an air-fuel ratio sensor having an element heating heater on the upstream side of a catalyst in an exhaust system and using hydrogen as fuel, and detecting the temperature related to the engine And a target air-fuel ratio setting means for setting a target air-fuel ratio according to the temperature detected by the temperature detection means, wherein the target air-fuel ratio setting means is a temperature detected by the temperature detection means. However, at the time of extreme cold below the first reference temperature, the target air-fuel ratio is set to a lean air-fuel ratio that is larger than the stoichiometric air-fuel ratio, while it is less than the second reference temperature that is higher than the first reference temperature and higher than the first reference temperature. In the cold state, the target air-fuel ratio is set to the stoichiometric air-fuel ratio or a rich air-fuel ratio smaller than the stoichiometric air-fuel ratio.

  According to the first invention, since hydrogen is used as a fuel, a decrease in emission performance is suppressed as compared with gasoline or the like even when an exhaust catalyst or the like is not activated.

  Here, if hydrogen is used as the fuel in a very low temperature, the moisture contained in the exhaust gas is cooled, and the air-fuel ratio sensor provided in the exhaust system may be flooded. When the detected temperature related to the engine is extremely cold below the first reference temperature, the target air-fuel ratio setting means sets the target air-fuel ratio to a lean air-fuel ratio larger than the stoichiometric air-fuel ratio. Is suppressed. Thereby, since the moisture of an element is suppressed, generation | occurrence | production of the element crack by the heating of the heater for element heating can be suppressed.

  On the other hand, when the temperature detected by the temperature detecting means is cold between the first reference temperature and the second reference temperature, the target air-fuel ratio setting means has a target air-fuel ratio that is smaller than the stoichiometric air-fuel ratio or the stoichiometric air-fuel ratio. Therefore, warm-up is promoted and the time until warm-up is completed is shortened. As a result, the generated water evaporates and the moisture of the element is suppressed, so that the occurrence of element cracking due to the heating of the element heating heater can be suppressed.

  As described above, by switching the target air-fuel ratio in accordance with the detected temperature related to the engine, it is possible to suppress element cracking due to flooding of the element without providing a plurality of air-fuel ratio sensors and covers. . Therefore, an increase in the number of parts can be suppressed, and an increase in assembly man-hours and an increase in cost can be suppressed.

  According to a second invention, in the first invention, the engine includes a generator that is driven to rotate by the engine to generate electric power, and applies a load to the engine during lean operation with a lean air-fuel ratio. It further comprises generator control means for controlling the generator.

  According to the second invention, the generator control means applies a load to the engine by generating the generator during the lean operation with the lean air-fuel ratio, so that the warm-up completion is suppressed while suppressing the generation of moisture in the exhaust system. It can be accelerated. In addition, since the engine warm-up is promoted by applying a load to the engine, it is possible to suppress the passenger from feeling uncomfortable compared to the case where the engine warm-up is promoted simply by increasing the engine speed. it can.

  According to a third aspect of the present invention, in the second aspect of the present invention, further comprising SOC detection means for detecting the SOC of a battery capable of charging / discharging the power generated by the generator, wherein the generator control means is detected by the SOC detection means. When the SOC of the battery is less than or equal to the first reference value, the battery is charged with power generated by the generator.

  By the way, when the temperature related to the engine is low, the temperature of the battery is often low. Then, when the temperature of the battery is extremely low, there is a possibility that large electric power cannot be drawn from the battery.

  Here, according to the third invention, when the SOC of the battery detected by the SOC detection means is equal to or lower than the first reference value, the generator control means charges the battery with the power generated by the generator. The SOC of the battery can be increased. In addition, by passing current through the battery in this way, heat is generated by the internal resistance of the battery and the battery is warmed from the inside, so that warming up of the battery can be promoted.

  In a fourth aspect based on the third aspect, the generator control means uses the electric power of the battery to the vehicle until the SOC of the battery reaches a second reference value lower than the first reference value. The control for operating the mounted electrical component and the control for charging the battery with the power generated by the generator until the SOC of the battery reaches the first reference value are alternately performed. .

  According to the fourth invention, between the first reference value and the second reference value of the SOC, the discharging of the battery due to the operation of the electrical components and the charging of the battery by the generator are alternately performed. Even so, the warm-up of the battery can be further promoted.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the target air-fuel ratio setting unit is a second unit in which the temperature detected by the temperature detection unit is set as a warm-up completion temperature of the engine. When the temperature is higher than the reference temperature, the target air-fuel ratio is set to a lean air-fuel ratio that is larger than the stoichiometric air-fuel ratio.

  According to the fifth invention, when the warm-up of the engine is completed, the target air-fuel ratio setting means sets the target air-fuel ratio to the lean air-fuel ratio, so that it is possible to improve the emission performance and the fuel consumption after the warm-up is completed. it can.

  According to the control device for a hydrogen engine according to the present invention, the target air-fuel ratio setting means sets the target air-fuel ratio to a lean air-fuel ratio when the temperature is extremely cold. Therefore, the occurrence of element cracking due to the heating of the element heating heater can be suppressed.

  On the other hand, since the target air-fuel ratio setting means sets the target air-fuel ratio to the stoichiometric air-fuel ratio or rich air-fuel ratio when cold, the time until the warm-up is completed is shortened, and the moisture of the element is suppressed by evaporation of the generated water. Therefore, the occurrence of element cracking due to the heating of the element heating heater can be suppressed.

  As described above, by switching the target air-fuel ratio in accordance with the detected temperature related to the engine, it is possible to suppress element cracking due to flooding of the element without providing a plurality of air-fuel ratio sensors and covers. .

It is a schematic block diagram of the hybrid vehicle carrying the control apparatus of the hydrogen engine which concerns on embodiment of this invention. It is a figure which shows an example of the engine control map which set the operating area | region of the engine. It is a schematic block diagram of the engine control apparatus. It is a circuit diagram of a linear air-fuel ratio sensor. It is a time chart of the engine control at the time of extremely cold start, in which (a) shows the time change of the engine water temperature, (b) shows the time change of the target air-fuel ratio, and (c) shows the battery temperature. FIG. 4D is a diagram showing the time change of the battery SOC. It is a time chart of the engine control at the time of extremely cold start, in which (a) shows the time change of the engine water temperature, (b) shows the time change of the target air-fuel ratio, and (c) shows the battery temperature. FIG. 4D is a diagram showing the time change of the battery SOC. It is a time chart of engine control at the time of cold start, (a) in the figure shows the change over time of the engine water temperature, (b) shows the change over time in the target air-fuel ratio, and (c) shows the time of the battery temperature. FIG. 4D is a diagram showing the time change of the battery SOC. FIG. 4 is a time chart of engine control at the time of warm start, in which FIG. (A) shows the time change of the engine water temperature, (b) shows the time change of the target air-fuel ratio, and (c) shows the battery temperature time. FIG. 4D is a diagram showing the time change of the battery SOC. It is a control flowchart of PCM. It is a flowchart explaining the control content of a generated power consumption control subroutine.

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

  FIG. 1 is a schematic configuration diagram of a hybrid vehicle equipped with a hydrogen engine control device according to an embodiment of the present invention. The vehicle 1 includes an engine 5 and first and second motors 7 and 9 as power sources. The engine 5 is used only for power generation, and all the power for moving the vehicle 1 depends on the motors 7 and 9. It is a series hybrid vehicle. The vehicle 1 is provided with a power train control module (PCM) 3 and a current and voltage sensor 61 in addition to the engine 5 and the first and second motors 7 and 9, and the first motor (generator) 7 and the second motor 1. A battery 11 capable of charging / discharging the electric power generated by the motor (traveling motor) 9, a first inverter 17 connected to the battery 11 and the first motor 7, the first inverter 17, the battery 11, and the second And a second inverter 19 connected to the motor 9.

  The engine 5 is a rotary engine, and is a dual fuel engine that can be driven by selectively switching between gasoline and hydrogen with less exhaust emissions when the catalyst is inactive than gasoline. . When hydrogen is selected by operating the fuel selector switch 63 (see FIG. 3), hydrogen in the hydrogen tank 13 is supplied to the injector 33 for hydrogen injection (see FIG. 3), while gasoline is selected. Then, the gasoline in the gasoline tank 15 is supplied to the injector 35 for gasoline injection. Exhaust emission refers to harmful components (HC, CO, NOx, etc.) contained in the exhaust gas after passing through the catalyst.

  The output shaft of the engine 5 is connected to the output shaft of the first motor 7, and the first motor 7 is rotationally driven by the engine 5 to generate electric power. The AC generated power generated by the first motor 7 is converted into DC power by the first inverter 17 and charged in the battery 11 or supplied to the second inverter 19.

  On the other hand, the second inverter 19 converts the DC power supplied by the discharge of the battery 11 or the DC power supplied from the first inverter 17 into AC power, and supplies the AC power to the second motor 9. The battery 11 is charged with the regenerative power from.

  The second motor 9 is connected to the left and right front wheels (drive wheels) 21a, 21a through the differential gear 23 among the four wheels 21a, 21a, 21b, 21b on the front, rear, left, and right, and according to the control map shown in FIG. Controlled by PCM3. That is, the second motor 9 is driven by the electric power supplied from the battery 11 at the time of low torque operation where the output torque required for the second motor 9 is low, such as during constant speed operation of the vehicle 1 or when the vehicle is started. (Region A in FIG. 2), high torque operation that is driven by electric power supplied from the first motor 7 driven by the engine 5 during medium torque operation (region B in FIG. 2) and has high output torque at the time of sudden acceleration, etc. Sometimes it is driven by electric power supplied from both the first motor 7 and the battery 11 (region C in FIG. 2). However, the engine 5 is warmed up at a cold start or the like, and when the SOC (State Of Charge) of the battery 11 is low, it is exceptionally the engine in all regions (region A, region B and region C). 5 is driven.

  Note that the SOC is an amount representing the state of charge of the battery 11, and the fully charged state is represented by SOC of 100%, while the state where the amount of charge is zero represents SOC of 0%. Further, since the open circuit voltage (voltage at no load) of the battery 11 and the SOC of the battery 11 have a one-to-one correspondence, the SOC can be obtained by measuring the voltage and current of the battery 11.

  As shown in FIG. 3, the engine 5 has rotors 27, 27 that are substantially triangular in rotor housing chambers (cylinders) 25, 25 surrounded by a bowl-shaped rotor housing having a trochoid inner peripheral surface and side housings. It is configured to be accommodated, and three working chambers are defined on the outer peripheral side thereof. Although not shown, the engine 5 is integrated by sandwiching two rotor housings between three side housings, and the rotors 27 and 27 are accommodated in two cylinders 25 and 25 formed therebetween, respectively. FIG. 3 shows the two cylinders 25, 25 in an expanded state.

  The rotor 27 rotates around the eccentric shaft 29 in a state where the seal portions respectively disposed on the three tops of the outer periphery are in contact with the inner peripheral surface of the trochoid of the rotor housing, and the axial center of the eccentric shaft 29 is rotated. Revolve around. Then, while the rotor 27 makes one rotation, the working chambers formed between the tops of the rotor 27 move in the circumferential direction, and intake, compression, expansion (combustion), and exhaust strokes are performed. Is generated from the eccentric shaft 29 via the rotor 27.

  The cylinders 25 and 25 of the engine 5 are provided with two spark plugs 31 and 31, respectively. The two spark plugs 31 and 31 are disposed near the short axis of the rotor housing, The cylinders 25 and 25 are provided with two injectors 33 for hydrogen injection for directly injecting the hydrogen supplied from the hydrogen tank 13 into the cylinder (only one is shown for each cylinder in FIG. 3). Each of the hydrogen injectors 33 is arranged in the axial direction of the eccentric shaft 29 in the vicinity of the long axis of the rotor housing.

  Each cylinder 25, 25 has an intake passage 37 communicating with the working chamber in the intake stroke, and an exhaust passage (exhaust system) 39 so as to communicate with the working chamber in the exhaust stroke. Communicate. The intake passage 37 and the exhaust passage 39 are connected by an EGR passage 41, and the exhaust of the exhaust passage 39 is operated by operating an EGR valve actuator 45 that controls the opening degree of the EGR valve 43 provided in the EGR passage 41. A part of the gas is returned to the intake passage 37.

  On the upstream side of the intake passage 37, an air flow sensor 67 that detects the intake amount and a throttle valve 47 that is driven by an actuator 49 such as a stepping motor to adjust the cross-sectional area of the intake passage 37 are disposed. A gasoline injection injector 35 for injecting gasoline supplied from the gasoline tank 15 into the intake passage 37 is disposed downstream of the passage 37. The exhaust passage 39 is provided with a three-way catalyst (catalyst) 51 as an exhaust purification catalyst for purifying exhaust.

  A linear air-fuel ratio sensor (air-fuel ratio sensor) 53 that detects the oxygen concentration in the exhaust gas is disposed upstream of the three-way catalyst 51. The linear air-fuel ratio sensor 53 is provided with a heater (element heater) 53b. The heater 53b heats the element portion 53a and maintains the element portion 53a at a predetermined temperature. More specifically, as shown in FIG. 4, the linear air-fuel ratio sensor 53 includes an oxygen concentration detection element section (element) 53a, a heater 53b for heating the element section 53a, and energization and detection signals for the element section 53a. A sensor circuit 53c for output and a heater energizing circuit 53d for energizing the heater 53b are provided.

  The element portion 53a has a pair of elements 53e and 53f made of an oxygen ion conductive solid electrolyte member such as zirconia. Both elements 53e and 53f function as an oxygen concentration ratio measuring battery element 53e and an oxygen pump element 53f, and electrode layers 53e ', 53e', 53f ', and 53f' are formed on both side surfaces thereof. Has been. A diffusion chamber 53h for introducing exhaust gas from the exhaust passage 39 through the diffusion layer 53g at a constant diffusion rate is formed between the two elements 53e and 53f, and on one side of the battery element 53e for measuring the oxygen concentration ratio. A comparative oxygen concentration chamber 53i is formed that is maintained at a constant oxygen concentration (for example, an oxygen concentration comparable to that of the atmosphere). The sensor circuit 53c connected to the element unit 53a includes an operational amplifier 53j, a resistor 53k, and the like, and outputs a signal from the output terminal 53m.

  Specifically, the linear air-fuel ratio sensor 53 detects the oxygen concentration in the exhaust gas as follows. That is, when the oxygen ion conductive solid electrolyte members constituting both elements 53e and 53f are disposed between two chambers having different oxygen partial pressures, oxygen ions corresponding to the ratio of the oxygen partial pressures in the two chambers are generated in the elements. When the voltage is applied between both electrodes, it functions as a battery, and when a voltage is applied between both electrodes, it functions as an oxygen pump that takes in oxygen from one side and releases oxygen to the other side.

  When the oxygen in the exhaust gas in the diffusion chamber 53h increases, oxygen is pumped out of the diffusion chamber 53h by the oxygen pump element 53f. When the oxygen in the exhaust gas in the diffusion chamber 53h is insufficient, the oxygen pump element 53f Oxygen is taken into the diffusion chamber 53h from the outside, and the oxygen in the oxygen concentration ratio measurement battery element 53e is changed via the operational amplifier 53j in accordance with a change in the voltage generated in the battery element 53e for oxygen concentration ratio so that the inside of the diffusion chamber 53h is maintained in a state corresponding to the theoretical air-fuel ratio. The voltage applied to the pump element 53f is adjusted, and accordingly, an output corresponding to the current flowing through the oxygen pump element 53f is taken out of the resistor and output from the output terminal 53m.

  The spark plugs 31 and 31, the EGR valve actuator 45, the actuator 49 of the throttle valve 47, the injectors 33 and 35 for hydrogen and gasoline injection, the first and second motors 7 and 9, the first and second inverters 17 and 19 The linear air-fuel ratio sensor 53 and the like are controlled by the PCM 3 as control means.

  The PCM 3 includes at least a vehicle speed sensor 55 that detects the speed of the vehicle 1, an accelerator opening sensor 57 that detects the accelerator opening, and a temperature related to the engine 5 as signals necessary for the control according to the present embodiment. Specifically, a water temperature sensor (temperature detecting means) 59 for detecting the engine water temperature Tw, the current sensor 61a and voltage sensor 61b, the fuel changeover switch 63, a battery temperature sensor 65 for detecting the temperature Tbat of the battery 11, and the airflow sensor 67. In addition, each output signal of the linear air-fuel ratio sensor 53 is input.

  In the control device for the hydrogen engine in the present embodiment, hydrogen is supplied from the hydrogen injection injector 33 to the engine 5 when hydrogen is used, and gasoline is supplied from the gasoline injection injector 35 to the engine 5 when gasoline is used. The engine 5 is driven. Further, the air-fuel ratio control is executed by the PCM 3 when using hydrogen and when using gasoline. That is, based on the output signal from the linear air-fuel ratio sensor 53, feedback control is performed to control the throttle opening and the engine speed so that the air-fuel ratio upstream of the three-way catalyst 51 becomes the target air-fuel ratio. .

  Here, when hydrogen is used as a fuel, a large amount of moisture is generated by the combustion of hydrogen, and the moisture may cause the element portion 53a of the linear air-fuel ratio sensor 53 to get wet on the upstream side of the three-way catalyst 51. . Thus, if the heater 53b is energized while the element portion 53a is flooded, the temperature of the flooded portion is unlikely to rise, so that the thermal stress of the element portion 53a becomes non-uniform and distortion occurs in the element portion 53a. There is a risk of device cracking. Such wetness of the element portion 53a is more likely to occur when the temperature of the engine 5 is extremely low, where the moisture contained in the exhaust gas is cooled. Further, since the three-way catalyst 51 is inactive when the temperature of the engine 5 is extremely low as described above, the exhaust emission increases as compared with when the temperature of the engine 5 is high.

  For this reason, in the control device for the hydrogen engine of the present embodiment, the target air-fuel ratio is started at an extremely cold temperature in order to prevent cracking of the element portion 53a of the linear air-fuel ratio sensor 53 and to reduce exhaust emissions when hydrogen is used. Set at the time of cold start and cold start.

  More specifically, the PCM 3 sets the target air-fuel ratio to a lean air-fuel ratio larger than the stoichiometric air-fuel ratio when the engine water temperature Tw detected by the water temperature sensor 59 is extremely cold below the first reference temperature Tw1, while the water temperature When the engine water temperature Tw detected by the sensor 59 is cold between the first reference temperature Tw1 and the second reference temperature Tw2 higher than the first reference temperature Tw1, the target air-fuel ratio is smaller than the theoretical air-fuel ratio or the theoretical air-fuel ratio. Set to rich air-fuel ratio. Further, when the engine water temperature Tw detected by the water temperature sensor 59 is equal to or higher than the second reference temperature Tw2 set as the warm-up completion temperature of the engine 5, the PCM 3 sets the target air-fuel ratio to a lean air temperature that is larger than the stoichiometric air-fuel ratio. Set to fuel ratio. As a result, the PCM 3 constitutes a target air-fuel ratio setting unit that sets the target air-fuel ratio in accordance with the detected engine water temperature Tw.

  Hereinafter, the control during the cold start, the cold start, and the warm start when hydrogen is used as the fuel will be described using a time chart.

-During cold start-
As shown in FIG. 5 (a), when the engine water temperature Tw detected by the water temperature sensor 59 is extremely cold below the first reference temperature Tw1, the PCM 3 receiving the signal from the water temperature sensor 59 is caused by hydrogen combustion. In order to suppress the generation of a large amount of moisture, the target air-fuel ratio is set to a lean air-fuel ratio as shown in FIG.

  Further, the PCM 3 outputs an execution command so that the first motor 7 generates power by the driving force of the engine 5 in order to apply a load to the engine 5 during the lean operation with the lean air-fuel ratio. Thus, the PCM 3 constitutes a generator control means for controlling the first motor 7 so as to apply a load to the engine 5 during the lean operation with the lean air-fuel ratio. Thus, by applying a load to the engine 5, warm-up of the engine 5 is promoted, and as shown in FIG. 5A, the engine water temperature Tw becomes equal to or higher than the first reference temperature Tw1.

  Then, when the engine water temperature Tw is cold, which is equal to or higher than the first reference temperature Tw1 and lower than the second reference temperature Tw2, in order to further promote the warm-up of the engine 5, as shown in FIG. The fuel ratio is set to a rich air fuel ratio (or a theoretical air fuel ratio). As a result, warm-up of the engine 5 is promoted, and the engine water temperature Tw becomes equal to or higher than the second reference temperature Tw2 as shown in FIG.

  When the engine water temperature Tw is warmer than the second reference temperature Tw2, the target air-fuel ratio is set to the lean air-fuel ratio again as shown in FIG. 5 (b) in order to improve the emission performance and the fuel efficiency after completion of warm-up. To do.

  Here, when the engine coolant temperature Tw is low, the temperature Tbat of the battery 11 is often low. Thus, when the temperature Tbat of the battery 11 is extremely low, large electric power cannot be drawn from the battery 11 and a large current may not be allowed to flow to the second motor 9.

  Therefore, the PCM 3 generates heat by the internal resistance of the battery 11 and warms the battery 11 from the inside. Therefore, when the detected SOC of the battery 11 is less than the first reference value (for example, 10 ° C.), The electric power generated by one motor 7 is configured to charge the battery 11.

  That is, as shown in FIG. 5C, when the battery temperature Tbat is lower than the reference battery temperature Tbat1 set as the warm-up completion temperature of the battery 11, the PCM 3 receiving the signal from the battery temperature sensor 65 The SOC of the battery 11 is calculated based on the current and voltage value of the battery 11 detected by the sensor 61a and the voltage sensor 61b. Thus, the PCM 3 constitutes an SOC detection means for detecting the SOC of the battery together with the current sensor 61a and the voltage sensor 61b. Then, as shown in FIG. 5 (d), if the SOC of the battery 11 is equal to or less than the first reference value SOC 1, the PCM 3 sends the electric power generated by the first motor 7 via the first inverter 17 to the battery 11. To charge.

  Here, it is sufficient that the battery temperature Tbat is equal to or higher than the reference battery temperature Tbat1 until the SOC of the battery 11 reaches the first reference value SOC1, that is, the warm-up of the battery 11 is completed. If the battery 11 continues to be charged with the electric power generated by one motor 7, the battery temperature Tbat exceeds the allowable range (for example, 10 ° C to 30 ° C).

  Therefore, the PCM 3 controls the electrical components mounted on the vehicle 1 using the charging power of the battery 11 until the SOC of the battery 11 reaches the second reference value SOC2 that is lower than the first reference value SOC1. And until the SOC of the battery 11 reaches the first reference value SOC1, the control for charging the battery 11 with the electric power generated by the first motor 7 is executed alternately.

  Specifically, until the SOC of the battery 11 that has reached the first reference value SOC1 reaches the second reference value SOC2, electric components (such as a heater (not shown) or the like mounted on the vehicle 1 using the charging power of the battery 11 are used. Activating the heat wave etc. of the front window. Then, when the SOC of the battery 11 reaches the second reference value SOC2, on the contrary, until the SOC of the battery 11 reaches SOC1, the electric power generated by the first motor 7 is passed through the first inverter 17 until the SOC reaches the second reference value SOC2. 11 is charged. As shown in FIGS. 5C and 5D, the PCM 3 performs the discharge of the battery 11 due to the operation of the electrical components and the charging of the battery 11 by the first motor 7 such that the battery temperature Tbat is equal to or higher than the reference battery temperature Tbat1. Repeat until.

  On the other hand, as shown in FIGS. 6A and 6C, even when the engine water temperature Tw is lower than the first reference temperature Tw1 and the battery temperature Tbat is extremely lower than the reference battery temperature Tbat1, 6 (d), the charging of the battery 11 by the first motor 7 and the discharging of the battery 11 by the operation of the electrical components are repeated, but before the battery temperature Tbat becomes equal to or higher than the reference battery temperature Tbat1, the engine The water temperature Tw may be equal to or higher than the first reference temperature Tw1. In this case, as shown in FIG. 6B, since the target air-fuel ratio is set to a rich air-fuel ratio, it is not necessary to apply a load to the engine 5, so the PCM 3 generates power from the first motor 7. As shown in FIG. 6D, the charging power of the battery 11 is discharged until the battery temperature Tbat becomes equal to or higher than the first reference battery temperature Tbat1.

  After the warm-up of the battery 11 is completed, the electric power generated by the first motor 7 is used for electric parts without charging the battery 11, so as shown in FIGS. 5 (d) and 6 (d), The SOC of the battery 11 does not change.

-At cold start-
As shown in FIG. 7A, when the engine water temperature Tw detected by the water temperature sensor 59 is cold between the first reference temperature Tw1 and lower than the second reference temperature Tw2, the PCM 3 that has received the signal from the water temperature sensor 59 is received. However, in order to promote warm-up of the engine 5, the target air-fuel ratio is set to a rich air-fuel ratio (or a stoichiometric air-fuel ratio) as shown in FIG.

  Thus, warming up of the engine 5 is promoted, and as shown in FIG. 7A, when the engine water temperature Tw detected by the water temperature sensor 59 becomes equal to or higher than the second reference temperature Tw2, the emission performance and the warming up are completed. In order to improve the fuel efficiency of the engine, the target air-fuel ratio is set to a lean air-fuel ratio as shown in FIG.

  Further, as shown in FIG. 7C, when the battery temperature Tbat is lower than the reference battery temperature Tbat1, the PCM 3 has a battery temperature Tbat equal to or higher than the first reference battery temperature Tbat1 as shown by a solid line in FIG. Until the battery 11 is discharged. Thus, the control for generating heat by the internal resistance of the battery 11 is repeated until the battery temperature Tbat becomes equal to or higher than the reference battery temperature Tbat1. Note that, as shown by a broken line in FIG. 7D, after the charging power of the battery 11 is discharged, the power generated by the first motor 7 may be charged to the battery 11.

-At warm start-
As shown in FIG. 8A, when the engine water temperature Tw detected by the water temperature sensor 59 is warmer than the second reference temperature Tw2, the PCM 3 receiving the signal from the water temperature sensor 59 improves the emission performance and fuel consumption. In order to improve, the target air-fuel ratio is set to a lean air-fuel ratio as shown in FIG.

  Further, as shown in FIG. 8C, when the battery temperature Tbat is slightly lower than the reference battery temperature Tbat1, the PCM 3 determines that the battery temperature Tbat is the first reference battery as shown by the solid line in FIG. The charging power of the battery 11 is discharged until the temperature becomes equal to or higher than the temperature Tbat1. Thus, the control for generating heat by the internal resistance of the battery 11 is repeated until the battery temperature Tbat becomes equal to or higher than the reference battery temperature Tbat1. Note that, as shown by a broken line in FIG. 8D, after the charging power of the battery 11 is discharged, the power generated by the first motor 7 may be charged to the battery 11.

-Processing operation of control device-
Here, the processing operation of the control device will be described based on the flowchart shown in FIG.

  First, in the first step SA1, the engine water temperature Tw detected by the water temperature sensor 59, the fuel selected by operating the fuel selector switch 63, the vehicle speed detected by the vehicle speed sensor 55, and the accelerator opening sensor 57 are detected. The PCM 3 reads the accelerator opening, the battery temperature Tbat detected by the battery temperature sensor 65, the current of the battery 11 detected by the current sensor 61a and the voltage value of the battery 11 detected by the voltage sensor 61b. Then, the process proceeds to step SA2.

  In the next step SA2, the PCM 3 calculates the SOC of the battery 11 based on the current and voltage value of the battery 11, and thereafter proceeds to step SA3. In the next step SA3, it is determined whether or not the engine water temperature Tw is lower than the second reference temperature Tw2. When the determination in step SA3 is NO, that is, when it is determined that the engine is warm start, the process proceeds to step SA4.

  In the next step SA4, it is determined whether or not battery discharge traveling is possible based on the SOC of the battery 11 calculated in step SA2. When the determination in step SA4 is YES, that is, when it is determined that traveling is possible only by the electric power supplied from the battery 11, the process proceeds to step SA5, where control is performed according to the control map shown in FIG. Then return. On the other hand, if the determination in step SA4 is no, the process proceeds to step SA6.

  In the next step SA6, it is determined whether or not hydrogen has been selected by operating the fuel selector switch 63. If the determination in step SA6 is NO, the process proceeds to step SA7, gasoline is selected as the fuel, and the target air-fuel ratio is set to the theoretical air-fuel ratio (λ = 1) in the next step SA8.

  In the next step SA9, feedback for determining the throttle opening and the engine speed N based on the vehicle speed and the accelerator opening read in step SA1 so that the air-fuel ratio upstream of the three-way catalyst 51 becomes the stoichiometric air-fuel ratio. Control is executed, and thereafter, the process proceeds to Step SA10.

  In the next step SA10, it is determined whether or not the battery temperature Tbat read in step SA1 is lower than the reference battery temperature Tbat1. When the determination in step SA10 is NO, that is, when the warm-up of the battery 11 is completed, the process returns as it is. On the other hand, when the determination in step SA10 is YES, the process proceeds to step SA11, and after discharging control for discharging the charging power of the battery 11 or discharging the charging power of the battery 11, the power generated by the first motor 7 is discharged. By executing the charge / discharge control for charging the battery 11, the battery 11 is warmed up, and then the process returns.

  On the other hand, when the determination in step SA6 is YES, the process proceeds to step SA12, hydrogen is selected as the fuel, and the target air-fuel ratio is set to a lean air-fuel ratio (λ> 1) in the next step SA15. On the other hand, when the determination in step SA3 is YES, the process proceeds to step SA13, forcibly selects hydrogen as the fuel, and then proceeds to step SA14. In the next step SA14, it is determined whether or not the engine water temperature Tw is lower than the first reference temperature Tw1, that is, whether or not it is extremely cold. When the determination in step SA14 is YES, the process proceeds to step SA15 to set the target air-fuel ratio to a lean air-fuel ratio (λ> 1). As described above, in both cases where the engine water temperature Tw is lower than the first reference temperature Tw1 and the engine water temperature Tw is equal to or higher than the second reference temperature Tw2, when the hydrogen is used as the fuel, the target air-fuel ratio is set to be lean in step SA15. The air-fuel ratio is set, and then the process proceeds to step SA16.

  In the next step SA16, it is determined whether or not the operating condition of the engine 5 is an idle operation in which the throttle valve 47 is almost fully closed. When the determination in step SA16 is YES, the process proceeds to step SA17.

  In the next step SA17, as in step SA3, it is determined whether or not the engine water temperature Tw is lower than the second reference temperature Tw2. When the determination in step SA17 is YES, that is, when it is determined that the temperature is extremely cold, the process proceeds to step SA18, and the first motor 7 is generated from the state where the throttle valve 47 is almost fully closed. The idle rotation control is executed at a throttle opening at which a torque for functioning as a machine is obtained, and then the process proceeds to step SA19.

  In the next step SA19, the PCM 3 controls the first motor 7 so as to apply a load to the engine 5 by generating the first motor 7, thereby promoting the warm-up of the engine 5, and then, in step SA20. After proceeding, the power consumption control described later is performed and then the process returns.

  On the other hand, when the determination in step SA17 is NO, that is, when it is determined that the warm-up of the engine 5 has been completed, the routine proceeds to step SA21, where the throttle valve 47 is almost fully closed. The valve 47 is fully opened to perform idle rotation control, and then the process proceeds to step SA24.

  In the next step SA24, it is determined whether or not the battery temperature Tbat read in step SA1 is lower than the reference battery temperature Tbat1. If the determination in step SA24 is NO, that is, if the warm-up of the battery 11 has been completed, the process directly returns. On the other hand, when the determination in step SA24 is YES, the process proceeds to step SA25, where the battery 11 is discharged or the battery 11 is charged / discharged, and then the process returns.

  On the other hand, when the determination in step SA16 is NO, that is, when it is determined that the operation condition of the engine 5 is not the idle operation, the process proceeds to step SA23. In the next step SA23, feedback control is executed to determine the throttle opening and the engine speed N based on the vehicle speed and the accelerator opening so that the air-fuel ratio upstream of the three-way catalyst 51 becomes the lean air-fuel ratio. Thereafter, the process proceeds to step SA24.

  In the next step SA24, it is determined whether or not the battery temperature Tbat is lower than the reference battery temperature Tbat1, and if the determination in step SA24 is NO, the process directly returns. On the other hand, when the determination in step SA24 is YES, the process proceeds to step SA25, where the battery 11 is discharged or the battery 11 is charged / discharged, and then the process returns.

  On the other hand, when the determination in step SA14 is NO, the process proceeds to step SA22 to set the target air-fuel ratio to the theoretical air-fuel ratio (λ = 1) or the rich air-fuel ratio (λ <1), and then proceeds to step SA23. .

  In the next step SA23, the throttle opening and the engine speed N are set based on the target air-fuel ratio, the vehicle speed and the accelerator opening so that the air-fuel ratio upstream of the three-way catalyst 51 becomes the stoichiometric or rich air-fuel ratio. The feedback control to be determined is executed, and then the process proceeds to step SA24.

  In the next step SA24, it is determined whether or not the battery temperature Tbat is lower than the reference battery temperature Tbat1, and if the determination in step SA24 is NO, the process directly returns. On the other hand, when the determination in step SA24 is YES, the process proceeds to step SA25, where the battery 11 is discharged or the battery 11 is charged / discharged, and then the process returns.

  Next, the generated power consumption control (step SA20) subroutine will be described with reference to the flowchart shown in FIG.

  First, in the first step SB1, it is determined whether or not the battery temperature Tbat read in step SA1 is lower than the reference battery temperature Tbat1. When the determination in step SB1 is NO, that is, when warming up of the battery 11 is completed, the process proceeds to step SB2. In the next step SB2, since the warm-up of the battery 11 has been completed, the power generated by the first motor 7 is used as an electrical component without charging the battery 11, and the generated power is consumed. .

  On the other hand, when the determination in step SB1 is YES, the process proceeds to step SB3. In the next step SB3, it is determined whether or not the SOC of the battery 11 calculated in step SA2 is equal to or less than the first reference value SOC1. When the determination in step SB3 is YES, the process proceeds to step SB4, and the power generated by the first motor 7 is increased via the first inverter 17 in order to increase the SOC of the battery 11 while promoting warming up of the battery 11. The battery 11 is charged, and then ends.

  On the other hand, when the determination in step SB3 is NO, that is, when the SOC of the battery 11 is higher than the first reference value SOC1, the process proceeds to step SB5 and is mounted on the vehicle 1 using the charging power of the battery 11. Then, the electric parts are operated, and thereafter, the process proceeds to Step SB6.

  In the next step SB6, the PCM3 reads the current and voltage values of the battery 11 detected by the current and voltage sensor 61 after using the charging power for the operation of the electrical components. In the next step SB7, the PCM3 Based on the current and voltage value of the battery 11 read in SB6, the SOC of the battery 11 is calculated, and then the process proceeds to step SB8.

  In the next step SB8, it is determined whether or not the SOC of the battery 11 calculated in step SB7 is equal to or less than the second reference value SOC2. If the determination in step SB8 is YES, the process ends. If NO, the process returns to SB5, and the electric components mounted on the vehicle 1 are operated using the charging power of the battery 11. That is, until the determination in step SB8 is YES, that is, until the SOC of the battery 11 becomes equal to or lower than the second reference value SOC2, the electric component mounted on the vehicle 1 is operated using the charging power of the battery 11.

-Effect-
According to this embodiment, since hydrogen is used as a fuel, even when the three-way catalyst 51 in the exhaust passage 39 is not activated, a reduction in emission performance is suppressed compared to gasoline or the like.

  Further, when the engine water temperature Tw detected by the water temperature sensor 59 is extremely cold when it is lower than the first reference temperature Tw1, the PCM 3 sets the target air-fuel ratio to the lean air-fuel ratio, so that the generation of moisture in the exhaust passage 39 is suppressed. Thereby, since the moisture of the element part 53a is suppressed, generation | occurrence | production of the element crack by the heating of the heater 53b can be suppressed.

  On the other hand, when the temperature detected by the water temperature sensor 59 is cold, which is equal to or higher than the first reference temperature Tw1 and lower than the second reference temperature Tw2, the PCM 3 sets the target air-fuel ratio to a rich air-fuel ratio. Time to complete warm-up is shortened. As a result, the generated water evaporates and the moisture of the element portion 53a is suppressed, so that the occurrence of element cracking due to the heating of the heater 53b can be suppressed.

  As described above, by switching the target air-fuel ratio according to the detected engine water temperature Tw, it is possible to suppress element cracking due to the flooding of the element portion 53a without providing a plurality of linear air-fuel ratio sensors, covers, and the like. it can. Therefore, an increase in the number of parts can be suppressed, and an increase in assembly man-hours and an increase in cost can be suppressed.

  Further, the PCM 3 applies a load to the engine 5 by generating the first motor 7 during the lean operation with the lean air-fuel ratio, so that the warm-up completion can be accelerated while suppressing the generation of moisture in the exhaust passage 39. Can do. Moreover, since warming up of the engine 5 is promoted by applying a load to the engine 5, compared with the case where warming up of the engine 5 is promoted simply by increasing the engine speed, the occupant feels uncomfortable. Can be suppressed.

  Furthermore, when the SOC of the battery 11 is equal to or less than the first reference value SOC1, the PCM 3 charges the battery 11 with the electric power generated by the first motor 7, so that the SOC of the battery 11 can be increased. In addition, by causing the current to flow through the battery 11 in this way, heat is generated by the internal resistance of the battery 11 and the battery 11 is warmed from the inside, so that warming up of the battery 11 can be promoted.

  Further, since the PCM 3 alternately discharges the battery 11 by the operation of the electrical components and charges the battery 11 by the first motor 7 between the first reference value SOC1 and the second reference value SOC2 of the SOC. Even when it is cold, the warm-up of the battery 11 can be further promoted.

  Further, when the warm-up of the engine 5 is completed, the PCM 3 sets the target air-fuel ratio to the lean air-fuel ratio, so that it is possible to improve the emission performance and the fuel efficiency after the warm-up is completed.

(Other embodiments)
The present invention is not limited to the embodiments, and can be implemented in various other forms without departing from the spirit or main features thereof.

  In the above-described embodiment, the vehicle 1 is a hybrid vehicle equipped with a dual fuel engine that can be driven by selectively switching the fuel used between gasoline and hydrogen. As long as it is, it may be simply a vehicle equipped with a rotary engine.

  Moreover, in the said embodiment, although 10-30 degreeC was illustrated as an allowable range of battery temperature Tbat1, you may determine suitably according to the capacity | capacitance of a battery, etc. not only this.

  As described above, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  As described above, the present invention is useful for a control device for a hydrogen engine using hydrogen as a fuel, provided with an air-fuel ratio sensor having an element heating heater on the upstream side of the catalyst in the exhaust system.

1 vehicle 3 PCM (target air-fuel ratio setting means) (generator control means) (SOC detection means)
5 Engine (hydrogen engine)
7 First motor (generator)
11 Battery 39 Exhaust passage (exhaust system)
51 Three-way catalyst (catalyst)
53 Linear air-fuel ratio sensor (air-fuel ratio sensor)
53b Heater (heater for element heating)
59 Water temperature sensor (temperature detection means)
61a Current sensor (SOC detection means)
61b Voltage sensor (SOC detection means)

Claims (5)

A control device for a hydrogen engine comprising an air-fuel ratio sensor having a heater for heating an element on the upstream side of an exhaust system catalyst and using hydrogen as fuel,
Temperature detecting means for detecting a temperature related to the engine;
A target air-fuel ratio setting means for setting a target air-fuel ratio according to the temperature detected by the temperature detection means,
The target air-fuel ratio setting means sets the target air-fuel ratio to a lean air-fuel ratio larger than the stoichiometric air-fuel ratio when the temperature detected by the temperature detection means is extremely cold below the first reference temperature. In a hydrogen engine characterized by setting the target air-fuel ratio to a stoichiometric air-fuel ratio or a rich air-fuel ratio smaller than the stoichiometric air-fuel ratio when the temperature is lower than the second reference temperature higher than the first reference temperature and lower than the second reference temperature. Control device. The hydrogen engine control device according to claim 1,
The engine has a generator that is driven by the engine to generate electricity,
A control device for a hydrogen engine, further comprising generator control means for controlling the generator so as to apply a load to the engine during lean operation with a lean air-fuel ratio. The control device for a hydrogen engine according to claim 2,
SOC detection means for detecting the SOC of the battery capable of charging and discharging the power generated by the generator,
The generator control means controls the hydrogen engine to charge the battery with power generated by the generator when the SOC of the battery detected by the SOC detection means is equal to or less than a first reference value. apparatus. The control device for a hydrogen engine according to claim 3,
The generator control means controls the electric component mounted on the vehicle to operate using the electric power of the battery until the SOC of the battery reaches a second reference value lower than the first reference value; A control device for a hydrogen engine that alternately executes control for charging the battery with electric power generated by the generator until the SOC of the battery reaches a first reference value. In the control device of the hydrogen engine according to any one of claims 1 to 4,
The target air-fuel ratio setting means sets the target air-fuel ratio to a lean value larger than the stoichiometric air-fuel ratio when the temperature detected by the temperature detection means is warmer than a second reference temperature set as the engine warm-up completion temperature. A control device for a hydrogen engine, characterized in that the air-fuel ratio is set.

Images