JP2010036776A - Charging control method and device for battery for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging control method and device for a battery for a vehicle which suppress an increase in engine speed during first fuel operation using first fuel whose caloric value in burn-up is low when a high voltage battery is charged in a hybrid vehicle equipped with a dual fuel engine using the first fuel and second fuel whose caloric value in burn-up is high as use fuel. <P>SOLUTION: The charging control method for a battery for a vehicle is used for a hybrid vehicle equipped with the dual fuel engine; a power generator for generating a power with the driving force of the engine; the battery; and a motor for driving a vehicle. The charging control method includes: a charging step for driving the power generator 3 by the engine 2, and for charging a battery 5 with a power generated by the power generator 3; an acceleration request determination step for determining the presence/absence of an acceleration request to the vehicle 1; and a charging suppression step for suppressing charging when it is determined that the acceleration request is present during the engine operation with the first fuel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charging control method and a charging control device for a vehicle battery, and more particularly to a charging control method and a charging control device for a vehicle battery that supplies electric power to a motor that outputs a driving force for driving the vehicle.

  Conventionally, a hybrid vehicle including a dual fuel engine capable of switching between fuel and gasoline is used (see, for example, Patent Document 1). The vehicle described in Patent Document 1 is configured to drive a motor by electric power generated by a generator driven by an engine and electric power supplied from a high-voltage battery, thereby giving driving force to the vehicle. .

  In this vehicle, the fuel to be used for driving the engine can be selected by the driver, and at least one of the engine (or the generator driven by the engine) or the high voltage battery is a motor according to the required output to the vehicle. It is configured to be selected as a power supply source for the vehicle, that is, a vehicle drive source.

  Further, in such a high-voltage battery of a hybrid vehicle, a lower limit value and an upper limit value are set in the usage range of the amount of stored electricity (SOC), and charging control is performed within this usage range. That is, when the charged amount falls below the lower limit value, a charge request is generated and charging is performed, and when the charged amount reaches the upper limit value, the charge request is lost and charging is stopped.

  In such charging control, the generated power of the generator is mainly used as charging power. When there is a charge request, the engine is increased more than the engine speed corresponding to the required output for the vehicle, and thereby the generator generates electric power that exceeds the required output. The required output power is supplied to the motor, and the surplus power is used for battery charging. Further, when the amount of charge of the high voltage battery reaches the upper limit due to charging, the charging request is lost, the engine speed is decelerated, and charging is stopped. As a result, the high voltage battery is held within a predetermined charged amount (SOC) range, and overdischarge and full charge are avoided.

Japanese Patent Laid-Open No. 2008-100520

  However, in a hybrid vehicle including a dual fuel engine as described in Patent Document 1, when compared with the same engine speed, the engine output is higher in the hydrogen gas operation than in the gasoline operation. For this reason, in order to obtain the same engine output, the engine speed is higher in the hydrogen gas operation than in the gasoline operation. Further, in gasoline operation, since there is a margin in output with respect to the required torque, even if the load increases, the engine speed is not significantly affected.

  Therefore, especially when the driver demands acceleration for the vehicle by depressing the accelerator and there is a request for charging, the engine speed is considerably higher during hydrogen gas operation than during gasoline operation. turn into. For this reason, there is a problem that the driver feels a great difference between the acceleration feeling and the noise from the engine between the hydrogen gas operation and the gasoline operation, which may cause the driver to feel uncomfortable.

  The present invention has been made in order to solve such a problem, and a first fuel (for example, hydrogen gas) having a low calorific value during combustion and a second fuel (for example, hydrogen gas) having a high calorific value during combustion relative to the first fuel. For example, in a hybrid vehicle equipped with a dual fuel engine using gasoline) as a fuel to be used, a request for charging a high voltage battery is made so as to reduce the difference in engine speed between the first fuel operation and the second fuel operation. It is an object of the present invention to provide a vehicle battery charge control method and a charge control device capable of suppressing an increase in engine speed during the first fuel operation.

  In order to achieve the above object, a vehicle battery charge control method according to the present invention includes a first fuel having a low calorific value during combustion and a second fuel having a high calorific value during combustion relative to the first fuel. A dual fuel engine that is selectively used and operated, a generator that generates electric power by the driving force of the engine, a battery that can be charged by the generator, a motor that can drive the vehicle by electric power from the generator and the battery, Charge control method for a vehicle battery in a hybrid vehicle comprising: a charging step in which a generator is driven by an engine, and the battery is charged by the generated electric power; and whether or not there is a predetermined acceleration request to the vehicle When it is determined that there is an acceleration request in the acceleration request determination step and the acceleration request determination step during the engine operation with the first fuel, It is characterized by comprising a charging suppressing step of suppressing the charging of electric step.

  According to the present invention configured as described above, when an acceleration request is made when a battery is charged by a generator driven by an engine during operation of the engine with the first fuel having a low calorific value during combustion, charging is performed. Is configured to be suppressed. Since the first fuel has a smaller amount of heat during combustion than the second fuel, the engine output becomes smaller. Therefore, in order to obtain the same engine output, the engine operation with the first fuel is more effective than the engine operation with the second fuel. However, the engine speed increases. For this reason, if charging is performed in a state where there is an acceleration request, the engine speed increases at an engine operation using the first fuel. However, in the present invention, in the engine operation with the first fuel, when there is an acceleration request during charging of the battery, control is performed so that the acceleration request is prioritized and the charging of the battery is suppressed. An increase in the rotational speed can be suppressed. This makes it possible to suppress engine noise and the like during engine operation using the first fuel.

  In the present invention, preferably, the method further includes a storage amount determination step for determining whether or not the storage amount of the battery is less than a predetermined threshold, and the charging step includes a storage amount of the battery less than the predetermined threshold in the storage amount determination step. In the storage amount determination step, the threshold value during engine operation with the first fuel is set to a value greater than the threshold value during engine operation with the second fuel. The According to the present invention configured as described above, it is possible to increase the charging frequency in the engine operation with the first fuel and to keep the SOC of the battery in a high state at all times. This can reduce the risk that the battery will be over-discharged even when there is a charge request in the engine operation with the first fuel and there is an acceleration request and the charge control is suppressed. it can.

  Preferably, the present invention further includes an engine speed determination step for determining whether or not the engine speed has reached a predetermined value, and the charge suppression step is determined to have an acceleration request in the acceleration request determination step. And it is performed when it is determined in the engine speed determination step that the engine speed has reached a predetermined value. According to the present invention configured as described above, when there is an acceleration request, charging is suppressed when it is determined that the engine speed has reached a predetermined value, so that the engine speed can be increased. In this way, a predetermined battery can be charged.

  In order to achieve the above object, the vehicle battery charging control apparatus according to the present invention includes any one of a first fuel having a low calorific value during combustion and a second fuel having a high calorific value during combustion relative to the first fuel. A dual fuel engine that is operated by selectively using one, a generator that generates electric power by the driving force of the engine, a battery that can be charged by the generator, and a motor that can drive the vehicle by electric power from the generator and the battery And a charge control device for a vehicle battery in a hybrid vehicle comprising: a charge control means for controlling the battery to be charged with electric power generated by the generator driven by the engine; Acceleration request determination means for determining whether or not there is an acceleration request, and during the operation with the first fuel, the acceleration request determination means determines that there is an acceleration request. It is characterized by comprising a charging suppression control means for performing control for suppressing the charging control by the charging control means.

  In the present invention, it is preferable that the battery control unit further includes a storage amount determination unit that determines whether or not the storage amount of the battery is less than a predetermined threshold value, and the charge control unit is configured such that the storage amount of the battery is determined by the storage amount determination unit. When it is determined that the battery is less than the threshold value, the control unit performs charging control of the battery, and the storage amount determination unit sets the threshold value when the engine is operated by the first fuel to be higher than the threshold value when the engine is operated by the second fuel. Set it to a large value.

  In the present invention, it is preferable that the engine speed determination means further determines whether or not the engine speed has reached a predetermined value, and the charge suppression control means determines that the acceleration request determination means has an acceleration request. When the engine speed determining means determines that the engine speed has reached a predetermined value, control for suppressing the charging control by the charge control means is performed.

  According to the vehicle battery charge control method and the charge control device of the present invention, a dual fuel engine that uses a first fuel having a low calorific value at the time of combustion and a second fuel having a high calorie value at the time of combustion as compared to the first fuel as the fuel used. In the hybrid vehicle equipped with the engine, when there is a request for charging the high voltage battery so as to reduce the difference in the engine speed between the first fuel operation and the second fuel operation, the engine rotation during the first fuel operation The increase in the number of rotations can be suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a configuration diagram of a hybrid vehicle, FIG. 2 is a configuration diagram of a dual fuel engine, FIG. 3 is an electrical block diagram of the hybrid vehicle, FIG. 4 is map data representing the relationship between accelerator opening and required output, and FIG. FIG. 6 is a timing chart of charge control, and FIG. 7 is a flowchart of charge suppression control. The map data represents the relationship between the rotational speed and the engine output.

  FIG. 1 is a configuration diagram of a hybrid vehicle 1 equipped with a dual fuel engine 2 according to an embodiment of the present invention. The vehicle 1 includes an engine 2, a generator (generator) 3, an AC-DC converter 4, a high-voltage battery 5, a DC-AC converter 6, a motor 7, and a controller 20 (for controlling them) 3).

In the vehicle 1, the engine 2 is operated by a control signal from the controller 20 and drives the generator 3 by the rotation output of the engine 2. Thereby, the generator 3 generates AC power and supplies the AC power to the AC-DC converter 4.
The AC-DC converter 4 converts the supplied AC power into DC power, and supplies the DC power to the high voltage battery 5 and the DC-AC converter 6. Thereby, the high voltage battery 5 is charged by the DC power supplied from the AC-DC converter 4 and supplies DC power to the DC-AC converter 6 in a predetermined operation state.

  The DC-AC converter 6 converts DC power supplied from at least one of the high-voltage battery 5 and the AC-DC converter 4 into AC power according to the operating state. The motor 7 is driven by AC power supplied from the DC-AC converter 6, and transmits the rotation output to the differential gear 8. The motor output is transmitted to the drive wheels 9 via the differential gear 8 so that the vehicle 1 travels.

As described above, the vehicle 1 according to the present embodiment is a series-type hybrid vehicle, in which the motor 7 is driven by electric power using the engine 2 and the high-voltage battery 5 as drive sources, and the drive wheels 9 are driven by the rotational output of the motor 7. It is configured to drive.
The vehicle 1 of the present embodiment is a series-type hybrid vehicle, but is not limited thereto, and may be a parallel-type or split-type hybrid vehicle. In this case, since the rotation output of the motor or the rotation output of the engine directly drives the drive wheel via the mechanical connection, the engine and the motor serve as a drive source.

  The dual fuel engine 2 of the present embodiment is a hydrogen gas that is a non-hydrocarbon first fuel having a low calorific value during combustion, and a hydrocarbon-based second fuel that has a high calorific value during combustion relative to the first fuel. Gasoline is used as fuel. In terms of volume, gasoline has a higher amount of heat during combustion than hydrogen gas, and in this embodiment, the gasoline operation mode is operated with a higher amount of heat during combustion than the hydrogen gas operation mode. The engine torque at the same engine speed (rpm) and throttle opening is greater in gasoline operation than in hydrogen gas operation.

As shown in FIG. 2, the engine 2 includes a housing 10 including a rotor housing having a trochoid inner peripheral surface and side housings disposed on both sides thereof, and a rotor accommodating chamber (hereinafter referred to as “cylinder”) formed in the housing 10. And a substantially triangular rotor 12 arranged at 11.
The engine 2 is a two-rotor type in which two rotor housings are integrated so as to be sandwiched between three side housings, and a rotor 12 is accommodated in each of two cylinders 11 formed therebetween. Only the cylinder 11 is shown.

  The rotor 12 is supported by an eccentric shaft 13 and is configured to rotate eccentrically with the eccentric shaft 13. The rotor 12 performs eccentric rotation in a state in which the seal portions respectively disposed on the three tops of the outer periphery are in contact with the trochoid inner peripheral surface of the rotor housing. Three working chambers are defined in the cylinder 11 on the outer peripheral side of the rotor 12. The volume of the working chamber changes due to the eccentric rotation of the rotor 12. The rotor 12 and the eccentric shaft 13 rotate through a series of steps of intake, compression, expansion (combustion), and exhaust in the working chamber, and the rotation output is transmitted to the generator 3 side.

In the following description, the configuration on the downstream side of the throttle valve 17 with respect to each rotor 12 is the same.
In the housing 10, two spark plugs 14 are provided for each cylinder 11. The housing 10 is formed with an intake port 15a and an exhaust port 15b. An intake passage 16a is connected to the intake port 15a, and an exhaust passage 16b is connected to the exhaust port 15b. Air is introduced into the working chamber in the intake process through the intake passage 16a, and exhaust gas is discharged from the working chamber in the exhaust process through the exhaust passage 16b.

A throttle valve 17 that is an electromagnetic valve is disposed upstream of the intake passage 16a, and an air cleaner 19 is disposed further upstream. The throttle valve 17 is provided with a throttle opening sensor 18 for detecting the opening.
Further, in the vicinity of the intake port 15a on the most downstream side of the intake passage 16a, a gasoline injector 30 that injects gasoline and supplies a mixture of air and gasoline into the working chamber, and hydrogen gas that injects hydrogen gas and air. Is provided with a port injection type hydrogen gas injector 40a for supplying an air-fuel mixture to the working chamber.

The gasoline injector 30 is connected to a gasoline tank 32 via a gasoline supply passage 31. The gasoline tank 32 is configured such that a gasoline pump 33 and the like are disposed in a main body that stores a predetermined volume of gasoline.
The gasoline pump 33 is configured to pump gasoline to the gasoline injector 30 via the gasoline supply passage 31.

Further, the housing 10 is provided with a direct-injection-type hydrogen gas injector 40b that directly injects hydrogen gas into the working chamber. The hydrogen gas injectors 40 a and 40 b are connected to a hydrogen high-pressure gas tank 42 through a hydrogen gas supply passage 41 that joins in the middle, and hydrogen gas is supplied from the hydrogen high-pressure gas tank 42.
The discharge port of the hydrogen high-pressure gas tank 42 is provided with a stop valve 43 for controlling the supply of hydrogen gas from the tank to the hydrogen gas supply passage 41, and further on the downstream side, hydrogen to the hydrogen gas injectors 40a and 40b. A control valve 44 for controlling the gas supply amount (supply pressure) is provided. The injectors 30, 40 a, 40 b are configured to inject a predetermined amount of gasoline or hydrogen gas at a predetermined injection timing based on a control signal from the controller 20.

  The controller 20 is a control device based on a well-known microcomputer, and is configured by a central processing unit (CPU) that executes a program storing an engine control method, for example, a RAM or a ROM, and stores the program and data. And an input / output (I / O) bus for inputting / outputting electrical signals.

  As shown in FIG. 3, the controller 20 includes a generator 3, an AC-DC converter 4, a DC-AC converter 6, a motor 7, a spark plug 14, a throttle valve 17, a throttle opening sensor 18, a gasoline injector 30, and a hydrogen gas injector. 40a and 40b, an operation mode selection switch 60, an accelerator opening sensor 61, a vehicle speed sensor 62, an engine speed sensor 63, a battery voltage sensor 23, a battery current sensor 24, etc., among which a detection signal is received from the detection sensor. The operation control is performed by outputting a control signal to the control target.

  The controller 20 includes a battery controller 21 and an HEV controller 22. The function of the battery controller 21 may be incorporated in the HEV controller 22 and the controller 20 may be integrated only in the HEV controller 22. Further, the sharing of functions of the battery controller 21 and the HEV controller 22 described below may be changed in the controller 20. The controller 20 includes a sensor and the like which will be described later, and constitutes the vehicle battery charge control device of the present invention.

  The battery controller 21 is configured to perform SOC control. That is, the battery controller 21 outputs a charge request signal to the HEV controller 22 so as to keep the charged amount (SOC) of the battery 5 within the use range (charge / discharge range). The SOC represents the amount of electricity charged with respect to the electric capacity of the battery as a ratio. In this specification, the amount of stored electricity is used synonymously with SOC.

In the present embodiment, the normal use range of the SOC of the battery 5 is defined as an upper limit of 60% and a lower limit of 40%. This use range has a width of 10% in the upper limit direction and the lower limit direction centering on SOC 50%, and is set so that the use range width is 20% as a whole. Accordingly, overdischarge and full charge of the battery 5 are suppressed, the driving range of the motor 7 by the battery 5 is set to be relatively large, battery running is increased, engine operation is suppressed, and fuel efficiency is improved. it can.
Further, the battery controller 21 performs a process of raising the lower limit value of the SOC usage range of the battery 5 within a range of values smaller than the upper limit value under a predetermined condition. As will be described later, this process is a process of raising the lower limit value of the SOC in the hydrogen gas operation mode to be higher than the lower limit value of the SOC in the gasoline operation mode.

The battery controller 21 is connected to a battery voltage sensor 23, a battery current sensor 24, and the like.
The battery voltage sensor 23 and the battery current sensor 24 detect the voltage and current of the battery 5 and output them to the battery controller 21. The battery controller 21 calculates the SOC of the battery 5 based on these voltages, current detection values, and the like. Specifically, the battery controller 21 integrates the current detection values, calculates the SOC variation from the total of the current input and output, and further stores internal data indicating the correspondence between the voltage detection value and the SOC. The current SOC is calculated by making corrections with consideration.

  When the calculated current SOC falls below the lower limit value of the use range, the battery controller 21 serving as the storage amount determination unit outputs a charge request signal to the HEV controller 22 and outputs the charge request signal. The charge request signal is continuously output until the SOC reaches the upper limit value of the use range. The HEV controller 22 performs charge control while receiving this charge request signal.

  Further, the HEV controller 22 outputs the driving force requested according to the accelerator opening degree from the motor 7 to the driving wheel 9, and the engine 2, the generator 3, the AC-DC converter 4, the DC-AC converter 6 and the motor. 7 etc. are controlled.

  In the present embodiment, the HEV controller 22 performs control to drive the motor 7 by switching the drive source in accordance with the operating conditions. That is, the HEV controller 22 operates the engine 2 and determines whether to drive the motor 7 with the electric power generated thereby or to drive the motor 7 with the electric power from the high voltage battery 5.

  Specifically, the HEV controller 22 needs to operate the engine 2 based on the detection signal indicating the accelerator and the vehicle speed from the accelerator opening sensor 61 and the vehicle speed sensor 62, that is, whether the engine 2 needs to be operated. Determine whether or not.

  For this determination, the HEV controller 22 uses map data (in order to determine which of the engine 2 and the high-voltage battery 5 is used to drive the motor 7 according to the relationship between the accelerator opening and the vehicle speed. (Not shown). Based on this map data, the HEV controller 22 performs control so that the motor 7 is driven by the electric power supplied from the high voltage battery 5 during low torque operation with a low required torque or when the vehicle is started. Further, the HEV controller 22 performs control so that the motor 7 is driven by electric power supplied from the generator 3 driven by the engine 2 during the medium torque operation. Further, the HEV controller 22 performs control so that the motor 7 is driven by electric power supplied from both the generator 3 and the high voltage battery 5 during high torque operation with a high required torque.

  In the present embodiment, the HEV controller 22 receives a charge request signal from the battery controller 21, and performs charge control of the battery 5 based on the charge request signal. That is, when the amount of power stored in the high-voltage battery 5 decreases and the HEV controller 22 receives a charge request signal from the battery controller 21, the HEV controller 22 adds to the power necessary for driving the motor 7 according to the required output. The engine 2 is operated so as to generate extra power required for charging the battery 5 by the generator 3, the motor 7 is driven, and the engine 2 is controlled so as to charge the high voltage battery 5. .

  At this time, the HEV controller 22 increases the engine rotational speed higher than the engine rotational speed necessary for generating electric power for driving the motor so that a power generation amount greater than the electric power necessary for driving the motor 7 is obtained. The engine 2 is controlled so that

  In the present embodiment, the vehicle 1 is provided with an operation mode selection switch 60 that can be selected by the driver. The driver can selectively select the operation mode of the engine 2 between the first operation mode using hydrogen gas and the second operation mode using gasoline by operating the operation mode selection switch 60. ing. The HEV controller 22 receives an operation mode selection signal output by operating the operation mode selection switch 60, and operates the ignition timing, the fuel used, the throttle so that the engine 2 is operated in the operation mode selected by the operation mode selection signal. An engine control process for controlling the opening degree and the like is performed.

  In the present embodiment, the operation mode is selected by manually operating the operation mode selection switch 60 by the driver. However, the present invention is not limited to this. The controller 20 may be configured to automatically switch the operation mode between the hydrogen gas operation mode and the gasoline operation mode according to the remaining amount of hydrogen gas.

Next, an outline of engine control according to the present embodiment will be described.
FIG. 4 is map data representing the relationship between the accelerator opening and the required output to the motor 7. The HEV controller 22 receives from the accelerator opening sensor 61 a signal representing the accelerator opening α that fluctuates when the driver operates the accelerator, and calculates a required output based on the map data of FIG.

FIG. 5 is map data showing the relationship between the engine speed (rpm) and the engine output (kW) in a steady state. In FIG. 5, a solid line A represents a gasoline operation mode, and a broken line B represents a hydrogen gas operation mode. These are tuned so that the maximum engine output P _max can be obtained at the maximum engine speed N _max .

  In the gasoline operation mode, the HEV controller 22 performs control so that the throttle opening is narrowed compared to the accelerator opening at least in the high rotation region so that the relationship shown by the solid line A is obtained. On the other hand, in the hydrogen gas operation mode, the HEV controller 22 always performs control for adjusting the load on the generator 3 side so as to maintain the throttle opening at the fully open position and achieve the target engine speed.

  The HEV controller 22 calculates the engine speed that achieves the required output calculated based on the accelerator opening α based on the map data of FIG. Then, the HEV controller 22 mainly performs control to weaken or strengthen power absorption by the generator 3 in both the gasoline operation and the hydrogen gas operation mode so as to achieve this engine speed.

Next, based on FIG.6 and FIG.7, the outline of the charge control of the controller 20 of this embodiment is demonstrated.
FIG. 6 is a timing chart of the charge control. FIG. 6A shows the time change of the operation mode selected by the operation mode selection switch 60, and FIG. 6B shows the time change of the accelerator opening α. (C) shows the change over time of whether or not the charging process is performed, (D) shows the change over time in the SOC of the battery 5, and (E) shows the supply of power from the battery 5 to the motor 7. The time change of presence / absence is shown, and FIG. 4F shows the time change of presence / absence of power supply from the engine 2 to the motor 7 via the generator 3.

Driver, the operation mode selection switch 60, from the time t ₀ to time t ₆ to continue selecting the gasoline operation mode to the operation mode, the operation mode is switched to the hydrogen gas operation mode to the time t _6, time t ₆ Thereafter, the hydrogen gas operation mode is selected as the operation mode.
The driver keeps the accelerator constant from time t ₀ to time t ₂ , and once depresses the accelerator to return again from time t ₂ to time t ₅ . Then, the driver, from the time t ₅ to time t ₈ holds the accelerator constant, back again depresses once the accelerator during the time t ₈ of time _10, holds a subsequent acceleration constant.

From time t ₀ to time t ₁ , the engine 2 is not driven, and power is supplied from only the battery 5 to the motor 7. Thereby, at time t ₁ , the SOC of the battery 5 is reduced to 40%, which is a normal lower limit value.
When the SOC of the battery 5 reaches the lower limit value, the battery controller 21 outputs a charge request signal to the HEV controller 22. Thereby, the HEV controller 22 as the charge control means drives the stopped engine 2 and stops the power supply from the battery 5 to the motor 7. The HEV controller 22 supplies driving power to the motor 7 from the engine 2 through the generator 3 and also supplies charging power to the battery 5.

By charging the battery 5 by the generator 3, the time t ₁ later, SOC of the battery 5 is gradually increased, reaching 60% which is the upper limit to the time t _3. Thereby, the battery controller 21 stops the output of the charge request signal, and the charging ends at time t ₃ .
Further, since the accelerator is depressed for a predetermined period after time t _{2 and} the time change rate of the accelerator opening α becomes positive or larger than a predetermined value, the HEV controller 22 as the acceleration request determination means determines that there is an acceleration request. . Thereby, since the required output of the motor 7 increases, the HEV controller 22 increases the engine speed according to the increase in the required output.

After charging is completed at time t ₃ , the HEV controller 22 performs control to supply power from the battery 5 to the motor 7 in addition to the generator 3 at time t ₄ . As a result, the SOC of the battery 5 decreases after the time t ₄ .
The time t _5, when it is held constant while the accelerator is returned, the vehicle 1 shifts to the steady operation. Accordingly, the HEV controller 22 performs control to stop the engine 2 and supply power from only the battery 5 to the motor 7. As a result, the SOC of the battery 5 continuously decreases.

When the operation mode is switched to the hydrogen gas operation mode at time t ₆ , the battery controller 21 receives an operation mode selection signal indicating the hydrogen gas operation mode via the HEV controller 22 and raises the lower limit value of the SOC to 45%. Process.
When the SOC of the battery 5 decreases to 45%, which is the raised lower limit value, at time t ₇ , the HEV controller 22 drives the engine 2 and stops supplying power from the battery 5 to the motor 7. The HEV controller 22 supplies driving power from the engine 2 to the motor 7 via the generator 3 and also supplies charging power to the battery 5. Thereby, the SOC of the battery 5 starts to rise.

However, when the accelerator is depressed at time t ₈ and the time change rate of the accelerator opening α becomes positive or larger than a predetermined value, the HEV controller 22 determines that there is an acceleration request. Thereby, the required output of the motor 7 increases. In the hydrogen gas operation mode, the HEV controller 22 as the charge suppression control means performs control to suppress charging even when there is a charge request when an acceleration request is generated.

  As described above, in the hydrogen gas operation mode, the engine speed is higher than that in the gasoline operation mode to supply the same engine output. In gasoline operation, since the output has a margin with respect to the required torque, the engine speed is not increased so much even if the load increases. When there is an acceleration request, the engine speed further increases, but when there is a charge request in addition to this, the engine speed further increases. As a result, in the hydrogen gas operation mode, the noise from the engine given to the driver increases in comparison with the gasoline operation mode, and the feeling of acceleration is reduced for the engine speed and engine sound. There is a risk of giving it to the driver.

Therefore, in the present embodiment, in the hydrogen gas operation mode, even when there is a charge request, if an acceleration request is generated, the acceleration request is prioritized and charging is suppressed. Therefore, the HEV controller 22 controls the engine 2 at the engine speed corresponding to the acceleration request without increasing the engine speed for charging. Thereby, in the hydrogen gas operation mode, an increase in engine speed can be suppressed.
In the charging suppression control process of the present embodiment, charging is completely stopped. However, the present invention is not limited to this, and the increase amount of the engine speed corresponding to the charge amount is set to a predetermined speed so as to reduce the charge amount. You may make it reduce.

Further, in the present embodiment, in the hydrogen gas operation mode, when an acceleration request is generated even when there is a charging request, charging of the battery 5 is suppressed, so that a period during which the battery 5 is charged is reduced. Therefore, the battery 5 may be overdischarged.
However, in the present embodiment, in the hydrogen gas operation mode, the lower limit value of the SOC of the battery 5, that is, the charging start voltage is increased in the hydrogen gas operation mode, so that the SOC of the battery 5 is increased in the absence of an acceleration request. Can be held in. Thereby, when the acceleration request | requirement arises, it becomes possible to reduce a possibility that the battery 5 will be overdischarged.

When the charging time t ₈ is stopped, so this time the battery 5 is not used to drive the motor 7, SOC of the battery 5 is kept constant. At time t ₉ , when the HEV controller 22 performs control to supply the electric power from the battery 5 to the motor 7 in addition to the generator 3, the SOC of the battery 5 decreases.

The time t _10, is held constant while the accelerator is returned, the vehicle 1 shifts to the steady operation. When the SOC of the battery 5 decreases again to 45%, which is the raised lower limit value, at time t ₁₁ , the HEV controller 22 stops supplying power from the battery 5 to the motor 7, and requests the motor 7. Control is performed to increase the engine speed so as to satisfy the output and charge. As a result, the SOC of the battery 5 starts to increase from time t ₁₁ and reaches 60%, which is the upper limit value, at time t ₁₂ .

When SOC of the battery 5 reaches the upper limit, the battery controller 21 stops outputting the charging request signal, the time t _12, HEV controller 22 terminates the charging.
Time t ₁₂ after the engine 2 is stopped, the electric power supplied from the battery 5 to the motor 7. Thereby, the SOC of the battery 5 decreases with time.
In the present embodiment, when there is an acceleration request in the hydrogen gas operation mode, the charging is configured to be stopped. However, not limited to this, the charging is temporarily stopped when the acceleration request is generated, and then You may comprise so that charge may be restarted when an acceleration request | requirement is lost.

FIG. 7 is a flowchart of the charge suppression control of this embodiment.
This control flow is started when the engine 2 is started. First, the controller 20 (HEV controller 22) reads the operation mode selection signal received from the operation mode selection switch 60 (step S1). Next, the HEV controller 22 reads the current SOC from the signal representing the SOC of the battery 5 received from the battery controller 21 (step S2).

Next, the HEV controller 22 determines whether or not the read operation mode selection signal indicates a hydrogen operation mode (step S3).
When the read operation mode selection signal indicates the hydrogen operation mode (step S3; Yes), the hydrogen gas operation mode is selected, and the controller 20 (battery controller 21) selects the SOC of the read battery 5. Corresponding to the hydrogen gas operation mode being performed, it is determined whether it is below 45%, which is the lower limit value of the SOC of the battery 5 that is set higher than in the gasoline operation mode (step S4; storage amount determination step) .

  When the SOC of the read battery 5 is lower than the raised lower limit (45%) (step S4; Yes), the battery controller 21 outputs a charge request signal and proceeds to step S6.

  On the other hand, when the SOC of the battery 5 is not below the raised lower limit (45%) (step S4; No), the controller 20 (HEV controller 22) determines whether or not the charging is currently being performed ( Step S5). In this case, when the HEV controller 22 has already received a charge request signal from the battery controller 21 and has performed charge control for the battery 5 based on the charge request signal, it is determined that charging is in progress.

If the battery is currently being charged (step S5; Yes), the current SOC is equal to or higher than the lower limit value but has not reached the upper limit value. Therefore, the battery controller 21 continues to output a charge request signal and proceeds to step S6. .
On the other hand, when the battery is not currently charged (step S5; No), the battery 5 is not being charged and the SOC of the battery 5 is maintained within the usage range (45% to 60%). Return to.

In step S6, the controller 20 (HEV controller 22) determines whether or not there is an acceleration request from the driver to the vehicle 1 based on the accelerator opening α read from the accelerator opening sensor 61 (step S6). ; Acceleration request determination step). That is, in step S6, it is determined whether or not the time change of the accelerator opening α is positive or larger than a predetermined positive threshold α ₀ , and the time change Δα of the latest accelerator opening α is determined. If it is positive or larger than the threshold value α _0, it is determined that the accelerator is depressed by the driver and there is an acceleration request.

  When there is an acceleration request (step S6; Yes), there is a charge request and an acceleration request during the hydrogen gas operation mode, so if charging is performed according to the charge request, the engine speed will become too large. In order to suppress the charge control, the charge control is stopped (step S9; charge suppression step), and the process returns to step S1. As described above, when it is determined that there is an acceleration request, charging control is suppressed regardless of whether a charging request is newly generated or when charging is already performed in response to the charging request.

  On the other hand, when there is no acceleration request (step S6; No), the charge request is generated in the hydrogen gas operation mode without the acceleration request. Therefore, the controller 20 (HEV controller 22) newly generates a charge request. When the charging is started, the charging control is started. When the charging is already performed in response to the charging request, the charging control is continued (step S7; charging step). In the charging control, the HEV controller 22 drives the engine 2 at an engine speed that takes into account the output request to the motor 7 and the output necessary for charging the battery 5, thereby driving the generator 3 to generate power. The battery 5 is charged with surplus power. In this case, for example, the engine speed is increased by about 1000 rpm.

Next, the controller 20 (HEV controller 22) determines whether or not the current SOC of the battery 5 has reached the upper limit value (60%) (step S8).
When the current SOC of the battery 5 has reached the upper limit (60%) (step S8; Yes), the HEV controller 22 stops the charging control, ends the process, and returns to step S1 again.
On the other hand, if the current SOC of the battery 5 has not reached the upper limit value (60%) (step S8; No), the HEV controller 22 steps again to continue the charge control without stopping the charge control. Return to S1.

  On the other hand, when the read operation mode selection signal does not represent the hydrogen operation mode (step S3; No), that is, when the gasoline operation mode is selected, the controller 20 (battery controller 21) reads the SOC of the read battery 5. Is lower than the lower limit (40%) of the SOC of the battery 5 set corresponding to the selected gasoline operation mode (step S10; charged amount determination step).

When the SOC of the read battery 5 is below the normal lower limit (40%) (step S10; Yes), the battery controller 21 outputs a charge request signal, and the HEV controller 22 performs the above-described operation in steps S7 to S9. Thus, charge control is performed within the range of the upper limit value of the SOC.
On the other hand, when the SOC of the battery 5 does not fall below the normal lower limit value (40%) (step S10; No), the controller 20 (HEV controller 22) determines whether or not the battery is currently being charged (step S10). S11).

When the current charging is in progress (step S11; Yes), since the current SOC is equal to or higher than the lower limit value but has not reached the upper limit value, the battery controller 21 continues to output a charge request signal, and the HEV controller 22 In steps S7 to S9, charge control is performed within the range of the upper limit value of the SOC as described above.
On the other hand, when the battery is not currently being charged (step S11; No), the battery 5 is not being charged and the SOC of the battery 5 is maintained within the use range.

  As described above, in the present embodiment, in the gasoline operation mode, when the SOC of the battery 5 falls below the lower limit value (40%), the rotational speed of the engine 2 is set so as to generate electric power that exceeds the required output for the motor 7. Increase. Then, surplus power is generated by the generator 3 to drive the motor 7 and charge control for charging the battery 5 with the surplus power is performed. In this case, this charging control is configured to be performed regardless of whether or not there is an acceleration request to the vehicle 1.

  On the other hand, in the hydrogen gas operation mode, when the SOC of the battery 5 falls below the lower limit (45%), the engine 2 is rotated so that electric power exceeding the required output for the motor 7 is generated, as in the gasoline operation mode. Increase. As a result, surplus power is generated by the generator 3 to drive the motor 7 and to perform charging control for charging the battery 5 with the surplus power.

  However, in the hydrogen gas operation mode, this charging control is configured to be suppressed when there is an acceleration request to the vehicle 1. Therefore, in the hydrogen gas operation mode, even when there is a charge request, if there is an acceleration request, the acceleration request is prioritized and charging control is not performed. As a result, when the acceleration is requested, the engine speed can be suppressed from being increased more than necessary.

  Further, in the present embodiment, in the hydrogen gas operation mode, even if there is a charge request, the charge control may be suppressed. Therefore, the lower limit value of the SOC of the battery 5 is raised by 5% from the lower limit value in the gasoline operation mode. Processing is in progress. Thereby, in the hydrogen gas operation mode, the SOC of the battery 5 is maintained higher than that in the gasoline operation mode, so that it is possible to prevent overdischarge when the charging control is suppressed.

Next, another embodiment of the present invention will be described with reference to FIG.
In the second embodiment, in the hydrogen gas operation mode, even if there is an acceleration request, the engine speed N is increased in a range up to a predetermined engine speed N _limit , and the battery is generated with surplus power generated by the increase. 5 is configured to be charged.

FIG. 8 is a flowchart of charge suppression control in another embodiment. Note that a description of processing common to the control flow of FIG. 7 is omitted.
This control flow is started when the engine 2 is started, similarly to the control flow of FIG. Steps S21 and S22 are the same as steps S1 and S2 in FIG.
Subsequently, following step S22, the controller 20 (HEV controller 22) reads the accelerator opening α from the signal representing the accelerator opening α received from the accelerator opening sensor 61 (step S3), and from the engine speed sensor 63. The engine speed N is read from the signal representing the received engine speed N (step S24).

Steps S25 to S31, S36 and S37 are the same as steps S3 to S9, S10 and S11 of FIG.
If there is an acceleration request in step S28 (step S28; Yes), the process proceeds to step S32.

In step S32, the controller 20 (HEV controller 22) as the engine speed determination means determines whether or not the read engine speed N is equal to a predetermined engine speed N _limit (step S32; engine speed). Judgment step). In the present embodiment, the engine speed N _limit is the maximum engine speed N _max , and the engine speed N is limited to the engine speed N _limit or less.

When the engine speed N is not equal to the predetermined engine speed N _limit (step S32; Yes), that is, when the engine speed N is smaller than the engine speed N _limit , the HEV controller 22 determines the current engine speed. It is determined whether or not N is obtained by increasing the number of rotations by a predetermined number of rotations (for example, 500 rpm) from the number of engine rotations necessary for generating electric power corresponding to the output request to the motor 7 (step S34). ).

When the current engine speed N is not increased by a predetermined speed (step S34; No), the HEV controller 22 increases the engine speed N _limit from the current engine speed to the limited engine speed N _limit . Since there is still room, control is performed to gradually increase the engine speed N within a range of the predetermined speed and not exceeding the engine speed N _limit (step S35).

For example, when the engine rotational speed N _limit is 6000 rpm and the current engine rotational speed N is 5000 rpm, the maximum rotational speed to be increased is set to 500 rpm, so the engine rotational speed N can be increased to 5500 rpm.

On the other hand, if the current engine speed N is 5600 rpm, increasing the engine speed by a predetermined engine speed (500 rpm) will exceed the engine engine speed N _limit. Number is suppressed. Thereby, the engine speed N is raised to 6000 rpm.
That is, in this embodiment, when the processes of steps S32 to S34 are repeated so as to increase the engine speed N by a predetermined speed, the engine speed N is changed to the engine speed N _limit on the way. When it reaches (step S32; Yes), the increase in the engine speed is limited (charging suppression step).

Thus, by increasing the engine speed N to the maximum engine speed, surplus power can be generated, and the battery 5 can be charged with this surplus power.
On the other hand, when the current engine speed N has been increased within the range of the predetermined engine speed (step S34; Yes), the engine speed N has already been increased to generate surplus power. Therefore, the HEV controller 22 performs control for charging the battery 5 within the range of the upper limit value of the SOC with the surplus power generated at the increased engine speed (steps S29 to S31).

When the engine speed N is equal to the predetermined engine speed N _limit (step S32; Yes), the HEV controller 22 determines whether charging is in progress (step S33).
When charging is not being performed (step S33; No), in the hydrogen gas operation mode, the engine 2 is operating at the maximum engine speed N _limit that is restricted by an output request to the motor 7, so the HEV controller 22 Since the engine speed N cannot be increased any more for charge control, the process is terminated and the process returns to step S21 again.

On the other hand, when charging is in progress (step S33; Yes), in the hydrogen gas operation mode, the engine speed N is increased to the maximum engine speed N _limit that is restricted for charge control by the processing described later. Therefore, the HEV controller 22 performs control to charge the battery 5 within the range of the upper limit value of the SOC with the surplus power generated at the increased engine speed (steps S29 to S31).

In this embodiment, the predetermined engine speed N _limit is set to the maximum allowable engine speed N _max , but is not limited to this, and is set to a relatively high engine speed. Also good. By setting in this way, in the hydrogen gas operation mode, charging control can be suppressed while charging the engine speed N to be equal to or lower than the set speed during charging.

1 is a configuration diagram of a hybrid vehicle according to an embodiment of the present invention. 1 is a configuration diagram of a dual fuel engine according to an embodiment of the present invention. 1 is an electric block diagram of a hybrid vehicle according to an embodiment of the present invention. It is map data showing the relationship between the throttle opening and required output by embodiment of this invention. It is map data showing the relationship between the engine speed and engine output by embodiment of this invention. It is a timing chart of charge control by an embodiment of the present invention. It is a flowchart of the charge suppression control by embodiment of this invention. It is a flowchart of the charge suppression control by other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hybrid vehicle 2 Dual fuel engine 5 High voltage battery 7 Motor 20 Controller 21 Battery controller 22 HEV controller 60 Operation mode selection switch

Claims (6)

A dual fuel engine that is operated by selectively using either the first fuel having a low calorific value at the time of combustion or the second fuel having a high caloric value at the time of combustion with respect to the first fuel, and generates electric power by the driving force of the engine A charging control method for a vehicle battery in a hybrid vehicle comprising: a generator; a battery that can be charged by the generator; and a motor that can drive the vehicle by electric power from the generator and the battery,
A charging step of driving the generator by the engine and charging the battery with the generated power;
An acceleration request determination step for determining whether there is an acceleration request greater than or equal to a predetermined value for the vehicle;
During engine operation with the first fuel, when it is determined that there is an acceleration request in the acceleration request determination step, a charge suppression step for suppressing charging in the charging step;
A charging control method for a vehicle battery, comprising: A storage amount determination step for determining whether the storage amount of the battery is less than a predetermined threshold;
The charging step is executed when it is determined in the storage amount determination step that the storage amount of the battery is less than a predetermined threshold,
2. The vehicle battery according to claim 1, wherein in the storage amount determination step, a threshold value during engine operation with the first fuel is set to a value larger than a threshold value during engine operation with the second fuel. Charge control method. An engine speed determination step for determining whether or not the engine speed has reached a predetermined value;
The charge suppression step is executed when it is determined in the acceleration request determination step that there is an acceleration request, and it is determined in the engine speed determination step that the engine speed has reached a predetermined value. The charging control method for a vehicle battery according to claim 1 or 2. A dual fuel engine that is operated by selectively using either the first fuel having a low calorific value at the time of combustion or the second fuel having a high caloric value at the time of combustion with respect to the first fuel, and generates electric power by the driving force of the engine A vehicle battery charge control device in a hybrid vehicle comprising: a generator; a battery that can be charged by the generator; and a motor that can drive the vehicle by electric power from the generator and the battery,
Charging control means for driving the generator by the engine and charging the battery with the electric power generated thereby;
Acceleration request determination means for determining whether or not there is an acceleration request greater than or equal to a predetermined value for the vehicle;
Charge suppression control means for performing control to suppress charge control by the charge control means when the acceleration request determination means determines that there is an acceleration request during operation with the first fuel, A vehicle battery charge control device. The battery further comprises a storage amount determination means for determining whether the storage amount of the battery is less than a predetermined threshold value,
The charge control unit performs control for charging the battery when the storage amount determination unit determines that the storage amount of the battery is less than a predetermined threshold,
5. The vehicle battery according to claim 4, wherein the storage amount determination unit sets a threshold value during engine operation using the first fuel to a value larger than a threshold value during engine operation using the second fuel. Charge control device. Engine speed determining means for determining whether or not the engine speed has reached a predetermined value;
The charging control means is determined when the acceleration request determining means determines that there is an acceleration request and when the engine speed determining means determines that the engine speed has reached a predetermined value. 6. The vehicle battery charge control device according to claim 4, wherein control for suppressing charge control by the vehicle is performed.

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