JP2018134924A - Control device for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a hybrid vehicle capable of shortening time to completion of starting while avoiding power shortage of electrical components at the time of starting of an internal combustion engine accompanying fuel heating.SOLUTION: A control device of the present invention performs control in which, when fuel heating is required at the time of starting of an internal combustion engine 2, fuel is injected while the internal combustion engine 2 is being cranked by a first motor generator 3 and while the fuel is heated by a glow plug 5. When a voltage supplied by a battery 15 for auxiliary equipment becomes lower than a predetermined value during the fuel heating by the glow plug 5, energization of the glow plug 5 is cut off, and the cranking of the internal combustion engine 2 by the first motor generator 3 is continued and the fuel injection is interrupted. Then, when the voltage of the battery 15 for the auxiliary equipment exceeds a determination value, the fuel heating and the fuel injection are resumed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device applied to a hybrid vehicle including an internal combustion engine that can be operated using a fuel containing alcohol.

  An internal combustion engine that can be operated using a fuel containing alcohol is less likely to vaporize as the alcohol content of the fuel increases, and the startability deteriorates. Thus, as a control device for a vehicle equipped with such an internal combustion engine, there has been proposed one that performs fuel injection while heating the fuel when the internal combustion engine is started (Patent Document 1).

JP-A-6-101608

  For heating the fuel, heating means such as an electric heater or a glow plug is used, and the electric power is supplied from an auxiliary battery provided as a power source for electric components of the vehicle. If the electric power load increases due to the use of the heating means at the time of starting the internal combustion engine, the voltage of the auxiliary battery may be lowered and the electrical component may malfunction.

  Accordingly, an object of the present invention is to provide a control device for a hybrid vehicle that can avoid malfunction of electrical components due to a voltage drop of an auxiliary battery at the time of starting an internal combustion engine with fuel heating.

  A control apparatus for a hybrid vehicle according to the present invention includes an internal combustion engine configured to be operable using a fuel containing alcohol, an electric motor capable of cranking the internal combustion engine, and a main battery that supplies electric power to the electric motor. Auxiliary battery provided as a power source for vehicle electrical components, power supply means for supplying power to the auxiliary battery, and driven by the auxiliary battery and used in the internal combustion engine A control device applied to a hybrid vehicle comprising heating means capable of heating fuel, and when the internal combustion engine needs to be heated when starting the internal combustion engine, the motor is cranking the internal combustion engine with the motor. Start control means for injecting fuel while heating the fuel by the heating means, and the start control means is configured to include the auxiliary battery during heating of the fuel by the heating means. When the voltage supplied by the engine becomes less than a predetermined value, the power consumption of the heating unit is reduced and the cranking of the internal combustion engine by the electric motor is continued. The power is returned to the state before the decrease.

  Note that reducing the power consumption of the heating means includes interrupting the fuel heating, that is, cutting off the energization of the heating means to reduce the power consumption to zero.

  According to the control device of the present invention, when the voltage supplied by the auxiliary battery becomes less than the predetermined value during the fuel heating by the heating means, the power consumption of the heating means is reduced. It is possible to avoid malfunction of the electrical equipment due to the voltage drop until it recovers. Further, while the power consumption of the heating means is being reduced, the cranking of the internal combustion engine by the electric motor using the main battery as a power source is continued. As a result, when the restart condition is satisfied and the power consumption of the heating means is restored and restarted, it is not necessary to restart cranking of the internal combustion engine from the beginning, so that the time until the start of the internal combustion engine can be shortened.

1 is a system configuration diagram of a hybrid vehicle to which a control device according to an embodiment of the present invention is applied. The functional block diagram which showed an example of the control system of the hybrid vehicle of FIG. 6 is a flowchart illustrating an example of a control routine according to an embodiment of the present invention. The flowchart which showed an example of the subroutine of FIG.

  As shown in FIG. 1, the vehicle 1 is configured as a series-parallel hybrid vehicle including an internal combustion engine 2 and two first and second generators 3 and 4. The internal combustion engine 2 is configured as an in-line four-cylinder internal combustion engine having four cylinders (not shown), for example, and can be operated using a fuel containing alcohol. The alcohol content of the fuel is allowed in the range of 0 to 100%. That is, the internal combustion engine 2 can be operated in any case where only gasoline is used as fuel, when a mixed fuel of gasoline and alcohol is used as fuel, and when only alcohol is used as fuel. In general, a vehicle equipped with an internal combustion engine that can be operated using an alcohol-containing fuel is referred to as a flexible fuel vehicle (FFV). Since the alcohol-containing fuel is harder to vaporize than gasoline, a glow plug 5 is provided for each cylinder for heating the fuel at the start to promote vaporization. The power consumption of the glow plug 5 during fuel heating is about 720 W (12 V, 60 A). The glow plug 5 corresponds to an example of a heating unit according to the present invention.

  The first motor / generator 3 is connected to the internal combustion engine 2 via a power split mechanism 6 configured as a planetary gear mechanism. The first motor / generator 3 functions as an electric motor that cranks when the internal combustion engine 2 is started, and also functions mainly as a generator during traveling when the internal combustion engine 2 is operated. The first motor / generator 3 corresponds to an example of an electric motor according to the present invention. The power output from the power split mechanism 6 is transmitted to the drive wheels 10. A second motor / generator 4 is connected to a power transmission path 7 between the power split mechanism 6 and the drive wheel 10 in a state where torque can be transmitted.

  The motor generators 3 and 4 are electrically connected to the HV battery 12 via an electric circuit (not shown), and the HV battery 12 supplies electric power to the motor generators 3 and 4. The HV battery 12 corresponds to an example of a main battery according to the present invention. The HV battery 12 is configured as a battery having a relatively high voltage of about 200 V DC, for example, a nickel metal hydride battery. The above electric circuits function as a DCDC converter and an inverter, respectively, can boost DC power of the HV battery 12 to convert it into AC power and supply it to the motor generators 3, 4. The generated power is converted into DC power while being decompressed and supplied to the HV battery 12. The HV battery 12 is also a power source for the in-vehicle air conditioner 13 of the vehicle 1.

  The vehicle 1 includes an auxiliary battery 15 provided as a power source for various electrical components. The auxiliary battery 15 is configured as a battery having a direct current of 12 V, which is lower in voltage than the HV battery 12, for example, a lead battery. As an electrical component that uses the auxiliary battery 15 as a power source, for example, an ECU including various electronic control units (ECUs) configured as a computer that controls a control target of the internal combustion engine 2, the motor generators 3, 4, etc. There are a group 20, an electric power steering device 21 that assists the steering operation of the vehicle 1, a brake device 22 that assists the braking operation of the vehicle 1, and the like. The auxiliary battery 15 is also used as a power source for the above-described glow plug 5 used for fuel heating, and the electric power of the auxiliary battery 15 is supplied to the glow plug 5 via a drive circuit (not shown).

  The auxiliary battery 15 is electrically connected to the HV battery 12 via the DCDC converter 25. Therefore, by operating the DCDC converter 25 connected to the HV battery 12, the power of the HV battery 12 can be supplied to the auxiliary battery 15 while being reduced to 14V, for example, and charged. The DCDC converter 25 can output up to 100 A, for example. The DCDC converter 25 functions as an example of power supply means according to the present invention.

  As shown in FIG. 2, the ECU group 20 described above includes an HVECU 30 that mainly controls the motor generators 3 and 4, and an engine ECU 31 that mainly controls the internal combustion engine 2. The HVECU 30 and the engine ECU 31 are connected to each other so as to be capable of two-way communication. The engine ECU 31 may control the internal combustion engine 2 alone, but basically controls the internal combustion engine 2 according to a command from the HVECU 30. Therefore, it can be said that the HVECU 30 controls the internal combustion engine 2 via the engine ECU 31.

  The HVECU 30 and the engine ECU 31 perform various controls on the vehicle 1 in cooperation with each other. For example, the internal combustion engine 2 is started in order to switch from the electric vehicle mode in which the internal combustion engine 2 is stopped and the vehicle is driven by the second motor / generator 4 to the hybrid mode in which the internal combustion engine 2 and the second motor / generator 4 are used as a driving source. To do. In order to perform various controls in addition to such start control, the HVECU 30 receives signals from various sensors that acquire information on each part of the vehicle 1. For example, the HVECU 30 includes a crank angle sensor 35 that outputs a signal corresponding to the rotational speed of the internal combustion engine 2, a resolver 36 that outputs a signal corresponding to the rotational speed of the first motor / generator 3, and a signal corresponding to the temperature of the fuel. The fuel temperature sensor 37 outputs a signal, the alcohol concentration sensor 38 outputs a signal corresponding to the alcohol concentration of the fuel, and the voltage sensor 39 outputs a signal corresponding to the voltage supplied by the auxiliary battery 15. Is done.

  3 and 4 show an example of a control routine executed by the HVECU 30 when the internal combustion engine 2 is started. The program for this control routine is held in the HVECU 30 and is repeatedly executed at predetermined intervals. The HVECU 30 functions as an example of the start control means according to the present invention by executing the control routines of FIGS. 3 and 4.

  As shown in FIG. 3, in step S <b> 1, the HVECU 30 determines whether there is a start request for the internal combustion engine 2. This start request is for generating a situation where the internal combustion engine 2 should be started, for example, when switching from the electric vehicle mode to the hybrid mode is necessary when the internal combustion engine 2 is stopped, or when the acceleration request is high when the vehicle 1 starts. In response, it is generated by the HVECU 30. If there is a start request, the process proceeds to step S2, and if not, the subsequent process is skipped and the current routine is terminated.

  In step S <b> 2, the HVECU 30 acquires the fuel temperature and alcohol concentration as the fuel state of the vehicle 1 by referring to the signals of the fuel temperature sensor 37 and the alcohol concentration sensor 38, respectively.

  In step S3, the HVECU 30 determines whether fuel heating is necessary. The alcohol-containing fuel is less likely to vaporize as the fuel temperature is lower and the alcohol concentration is higher, and the startability is deteriorated. Therefore, the HVECU 30 determines whether fuel heating is necessary based on threshold values set for the fuel temperature and the alcohol concentration, for example. If fuel heating is necessary, the process proceeds to step S4. If not, step S4 is skipped and the process proceeds to step S5.

  In step S4, the HVECU 30 issues a command to the engine ECU 31 to start fuel heating. In response to the command, the engine ECU 31 controls a drive circuit provided in the glow plug 5 so that the glow plug 5 is energized and fuel heating is started. As a result, the glow plug 5 generates heat and fuel heating is started.

  In step S5, the HVECU 30 performs power running control on the first motor / generator 3 while referring to the signals of the crank angle sensor 35 and the resolver 36 so that the internal combustion engine 2 is cranked (motored) at a predetermined rotational speed. To do. In subsequent step S6, the HVECU 30 issues a command to the engine ECU 31 so that fuel injection and spark ignition of the internal combustion engine 2 are performed. The engine ECU 31 performs fuel injection and spark ignition at an appropriate timing while referring to the crank angle sensor 35 in response to the command. The fuel injection amount and the ignition timing are appropriately adjusted according to the alcohol concentration of the fuel.

  In step S7, the HVECU 30 determines whether or not the internal combustion engine 2 has completely exploded. The HVECU 30 determines that the complete explosion has occurred when the rotational speed of the internal combustion engine 2 exceeds a threshold set for determining complete explosion. When the internal combustion engine 2 has not completely exploded, the process proceeds to step S8, and the HVECU 30 determines whether or not the fuel is being heated. If the fuel is being heated, the process proceeds to step S9, where the HVECU 30 executes the heating interruption process shown in detail in FIG. 4 that is executed to interrupt or continue the fuel heating, and the process returns to step S5. If the fuel is not being heated, step S9 is skipped, and the process returns to step S5 in order to continue the start control including cranking, fuel injection, and spark ignition. Note that if it is determined in step S7 that complete explosion has occurred, start-up is completed, and thus the process proceeds to step S10, where the HVECU 30 determines whether fuel is being heated. If the fuel is being heated, the process proceeds to step S11, where the HVECU 30 cuts off the energization of the glow plug 5, ends the fuel heating, and ends the current routine. On the other hand, if the fuel is not being heated, step S11 is skipped and the current routine is terminated.

  As shown in FIG. 4, in step S <b> 91, the HVECU 30 refers to the signal from the voltage sensor 39 and acquires the voltage Vc supplied from the auxiliary battery 15. In subsequent step S92, the HVECU 30 determines whether or not the voltage Vc is less than a predetermined value PV. The predetermined value PV is set within the allowable range of the voltage at which the electrical equipment using the auxiliary battery 15 as a power source operates without any problem, and the predetermined value PV is expected to have a margin on the higher voltage side than the lower limit value of the allowable range. Is set appropriately. Therefore, when the voltage Vc is equal to or higher than the predetermined value PV, there is no problem even if the fuel heating using the glow plug 5 is continued, so that the subsequent processing is skipped and the process returns to the main routine of FIG. On the other hand, if the voltage Vc is less than the predetermined value PV, the operation of the electrical component may be hindered if the fuel heating is continued. Therefore, the HVECU 30 executes the processes of steps S93 to S95. In addition, since the allowable range of the voltage described above may vary depending on, for example, the outside air temperature, the predetermined value PV may be changed according to the outside air temperature.

  In step S93, the HVECU 30 issues a command to the engine ECU 31 so that fuel heating is interrupted. In response to the command, the engine ECU 31 interrupts the fuel heating by controlling the drive circuit so that the energization of the glow plug 5 is interrupted.

  In step S94, the HVECU 30 issues a command to the engine ECU 31 so that fuel injection and spark ignition are interrupted. In response to the command, the engine ECU 31 controls the internal combustion engine 2 so that fuel injection and spark ignition are interrupted.

  In step S 95, the HVECU 30 refers to the signals of the crank angle sensor 35 and the resolver 36 and monitors the rotational speeds of the internal combustion engine 2 and the first motor / generator 3 while monitoring the internal combustion engine 2 by the first motor / generator 3. Continue ranking. That is, in the heating interruption process shown in FIG. 4, fuel heating, fuel injection, and spark ignition are interrupted, but cranking of the internal combustion engine 2 is continued.

  In step S96, the HVECU 30 determines whether or not a restart condition for determining restart of the interrupted fuel heating, fuel injection, and spark ignition is satisfied. As described above, since the power of the HV battery 12 is supplied to the auxiliary battery 15 by operating the DCDC converter 25, the reduced voltage Vc can be recovered by interrupting the fuel heating. Therefore, in this embodiment, the HVECU 30 determines that the resumption condition is satisfied when the voltage Vc is recovered to a determination value JV that is higher than the predetermined value PV used for determining the interruption. In the case of this embodiment, the determination value JV is higher than the predetermined value PV. Therefore, when the supply voltage Vc of the auxiliary battery 15 changes in the vicinity of the predetermined value PV, the interruption and restart of the fuel heating are repeated in a short time. Such instability of control can be suppressed. However, instead of this, the determination value JV may be set to the same value as the predetermined value PV. Further, the determination value JV may be a fixed value or a fluctuation value. Note that the restart condition is not necessarily based on the voltage Vc. Since the voltage recovers as the fuel heating interruption time elapses, for example, the restart condition may be that a predetermined time has elapsed since the fuel heating interruption was started. If the restart condition is satisfied, the process proceeds to step S97. On the other hand, if the restart condition is not satisfied, the process returns to step S93, the interruption of fuel heating, fuel injection, and spark ignition is maintained, and cranking is continued.

  In step S97, the HVECU 30 issues a command to the engine ECU 31 so that fuel injection and spark ignition are resumed. In response to the command, the engine ECU 31 controls the internal combustion engine 2 so that fuel injection and spark ignition are restarted at appropriate timing. In the subsequent step S98, the HVECU 30 issues a command to the engine ECU 31 so that fuel heating is resumed. The engine ECU 31 resumes the heating of the fuel by resuming energization to the glow plug 5 and returns to the main routine of FIG.

  According to the control routine of FIG. 3 and FIG. 4, when the voltage Vc supplied from the auxiliary battery 15 becomes less than the predetermined value PV during fuel heating by the glow plug 5, the energization of the glow plug 5 is cut off. It is possible to avoid malfunction of the electrical equipment until the supply voltage Vc of the auxiliary battery 15 is recovered. Further, since fuel injection is interrupted while fuel heating by the glow plug 5 is interrupted, problems such as misfire due to insufficient heating of the fuel can be avoided. Further, while the fuel heating and fuel injection are interrupted, the cranking of the internal combustion engine 2 by the first motor / generator 3 using the HV battery 12 as a power source is continued. Therefore, at the time of restart when the resumption condition is satisfied and the fuel heating is restored, it is not necessary to perform cranking of the internal combustion engine 2 from the beginning, so that the time until the start of the internal combustion engine 2 is completed can be shortened.

  This invention is not limited to the said form, It can implement with a various form within the range of the summary of this invention. The above embodiment is intended for a series-parallel type hybrid vehicle including the first motor / generator 3 and the second motor / generator 4 in addition to the internal combustion engine 2, and is electrically connected to the HV battery 12. Although the internal combustion engine 2 is cranked using the generator 3 as an electric motor, the present invention is not limited to this form. For example, in addition to the internal combustion engine, a parallel hybrid vehicle provided with a single electric motor in a state where power can be transmitted to the internal combustion engine is used, and the electric motor electrically connected to the main battery is used. Thus, the present invention can be implemented in a form in which the internal combustion engine is cranked.

  In the above embodiment, as an example of reducing the power consumption of the heating means, the energization of the glow plug 5 is interrupted to reduce the power consumption to zero. However, the energization of the glow plug 5 is continued but the drive is performed so that the power consumption is reduced. It is also possible to change to a form in which the circuit is controlled. In this case, the temperature of the glow plug 5 can be quickly raised when the fuel heating is returned to the normal time. The reduction rate of the power consumption of the glow plug 5 may be determined as appropriate. For example, the power consumption may be reduced so that the reduction rate is 70% compared to the normal time, that is, the glow plug 5 is driven with power consumption of 30%. In the above embodiment and this modification, the fuel heating can be performed by providing, for example, an electric heater instead of the glow plug 5 as a heating means.

  In the above embodiment, the DCDC converter 25 that supplies the power of the HV battery 12 to the auxiliary battery 15 is provided as an example of the power supply means, but the present invention is not limited to this embodiment. For example, for a vehicle provided with an alternator driven by a crankshaft of an internal combustion engine and electrically connected to an auxiliary battery, the generated power generated by the alternator during cranking by the electric motor is used as the auxiliary battery. The power supply means may be realized in the form of supply.

  In the above embodiment, the power consumption of the heating means is reduced and the fuel injection and the spark ignition are interrupted. For example, while the power consumption of the heating means is reduced, the fuel injection and the spark ignition are respectively continued. Or, the fuel injection may be interrupted and the spark ignition may be continued.

Moreover, the said form can be grasped | ascertained also as embodiment in invention of the following control apparatus.
That is, an internal combustion engine configured to be operable using a fuel containing alcohol, an electric motor capable of cranking the internal combustion engine, a main battery for supplying electric power to the electric motor, and a power source for electrical components of the vehicle Auxiliary battery provided, power supply means for supplying power to the auxiliary battery, heating means driven by the auxiliary battery as a power source and capable of heating fuel used in the internal combustion engine, When the fuel heating is required for starting the internal combustion engine, the fuel is heated by the heating means while cranking the internal combustion engine by the electric motor. Start control means for performing fuel injection while the fuel supplied by the auxiliary machine battery is less than a predetermined value during fuel heating by the heating means. When it becomes, reducing the power consumption of the heating means and continuing the cranking of the internal combustion engine by the electric motor, if a predetermined restart condition is satisfied, the power consumption of the heating means is returned to the state before the reduction, It is determined that the resumption condition is satisfied when the voltage recovers to a determination value higher than the predetermined value. According to this control device, the determination value used for the determination of returning the power consumption of the heating means to the original state is higher than the predetermined value used for the determination of reducing the power consumption. When the supply voltage changes in the vicinity of a predetermined value, it is possible to suppress the instability of control such that the reduction and return of power consumption of the heating means are repeated in a short time.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Internal combustion engine 3 1st motor generator (electric motor)
5 Glow plug (heating means)
12 HV (main battery)
15 Auxiliary battery 25 DCDC converter (power supply means)
30 HVECU (starting control means)

Claims (1)

An internal combustion engine configured to be operable using a fuel containing alcohol;
An electric motor capable of cranking the internal combustion engine;
A main battery for supplying power to the motor;
An auxiliary battery provided as a power source for vehicle electrical components;
Power supply means for supplying power to the auxiliary battery;
Heating means driven by the auxiliary battery as a power source and capable of heating fuel used in the internal combustion engine;
A control device applied to a hybrid vehicle comprising:
When fuel heating is required at the time of starting the internal combustion engine, the engine includes start control means for performing fuel injection while heating the fuel with the heating means while cranking the internal combustion engine with the electric motor,
When the voltage supplied from the auxiliary battery becomes less than a predetermined value during the fuel heating by the heating means, the start control means reduces the power consumption of the heating means and reduces the power consumption of the internal combustion engine by the electric motor. A control apparatus for a hybrid vehicle, wherein ranking is continued and when a predetermined restart condition is satisfied, the power consumption of the heating means is returned to the state before the decrease.

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