JP2007223458A - Hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hybrid vehicle whose engine is efficiently operated to reduce total fuel consumption. <P>SOLUTION: The SOC lower limit of a main electric storage device, i.e., the requirement for starting the engine, is changed from its normal value LLIM to a lower reduced value #LLIM only if a driving force by a motor generator is not requested. If the generation of the driving force from the motor generator is not requested, the electric power discharged from the main electric storage device is limited to relatively small loads such as an air conditioner and low-voltage auxiliaries. Based on a shift position obtained, a controller determines whether or not the generation of the driving force from the motor generator is required, and changes the SOC lower limit for protecting the main electric storage device from an overdischarge. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hybrid vehicle equipped with a power storage device, and more particularly to charge / discharge control technology for a power storage device.

  In recent years, hybrid vehicles have attracted much attention as environmentally friendly vehicles. A hybrid vehicle is an automobile that further includes a power storage device including a secondary battery and a motor that generates electric power from the power storage device and a driving force of the vehicle in addition to a conventional engine. In such a hybrid vehicle, the engine is stopped when the driving force is not required or when the required amount is small, such as when the vehicle is stopped or starting.

  On the other hand, a power storage device mounted in such a hybrid vehicle supplies power to the motor when the vehicle starts or accelerates, and stores power generated by the motor (functioning as a generator) during regenerative braking of the vehicle. Is required. Therefore, charge / discharge control is executed so that SOC (State Of Charge) indicating the state of charge of the power storage device falls within the SOC management range including a predetermined control center value.

  As part of such charge / discharge control, as disclosed in Patent Document 1, when the SOC of the power storage device falls below the SOC lower limit value while the engine is stopped, the engine is started to increase the SOC of the power storage device. Then, the power storage device is charged by the electric power from the motor or the generator.

Further, as disclosed in Patent Document 2, when a shift position selected by a driver's operation is determined, generation of electric power accompanying regenerative braking such as a parking (parking) position or a reverse (reverse) position cannot be expected. Is controlled to start the engine at a relatively high SOC.
Japanese Unexamined Patent Publication No. 07-250404 Japanese Patent Laid-Open No. 11-122713 JP 2005-45883 A

  Such a hybrid vehicle is equipped with various auxiliary machines. Among such auxiliary machines, those that are required to operate regardless of the operating condition of the engine, such as an air conditioner and a car navigation system, operate by receiving electric power from the power storage device even when the engine is stopped. Configured as follows.

  For example, when the air conditioner is activated immediately after the driver turns on the ignition key, the engine is maintained in a stopped state, while the electric power stored in the power storage device is preferentially used. The Thereafter, when the SOC of the power storage device falls below a predetermined SOC lower limit value, the engine is started and electric power is generated for use in charging the power storage device and operating the air conditioner.

  Therefore, when the driver is in the vehicle and waits for the passenger for a long time, the engine is frequently used only for power generation due to the decrease in the SOC of the power storage device accompanying the operation of the auxiliary machinery. It will be started. In the case of aiming only at such power generation, there is a problem that the engine must be operated in a rotational speed range where the combustion efficiency is relatively poor, and the fuel consumption increases unnecessarily when viewed comprehensively. It was.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a hybrid vehicle that efficiently operates the engine and suppresses the total fuel consumption. is there.

  According to the present invention, the engine, the power generation means that is mechanically coupled to the engine and generates power using the output of the engine, the power storage unit configured to be rechargeable by the power generated by the power generation means, and driving of the vehicle An electric force generating means that is mechanically coupled to the shaft and generates the driving force of the vehicle using the electric power from the power storage unit, and a power generation unit when a state value indicating a charging state of the power storage unit is lower than a lower limit determination value. It is a hybrid vehicle provided with the control part which starts an engine in order to supply the charging power of an electrical storage part. The control unit is requested to generate a driving force from the electric force generating means by the shift position determining means for determining which one of the plurality of shift positions is selected by the operation of the driver and the shift position determining means. When it is determined that the shift position to be obtained is selected, the first lower limit value setting means for setting the lower limit determination value to the first value and the shift position determination means generate driving force from the electric force generation means. And a second lower limit setting means for setting the lower limit determination value to a second value lower than the first value when it is determined that a shift position that cannot be required is selected.

  According to the present invention, the control is performed in the case where the shift position where the generation of the driving force from the electric force generation means cannot be requested is selected, that is, when the relatively large electric power cannot be requested from the power storage unit. The unit sets a lower limit determination value for starting the engine to a lower value. Therefore, in a situation where predetermined power is output from the power storage unit, it is possible to extend the period until the engine is started to charge the power storage unit. Thus, unnecessary fuel consumption can be suppressed by reducing the frequency of engine operation in a region where combustion efficiency is relatively low for the purpose of charging only the power storage unit.

  Preferably, the hybrid vehicle according to the present invention further includes an auxiliary machine load that is operated by electric power from the power storage unit, and the second lower limit value setting means sets the second value in accordance with the operating state of the auxiliary machine load. decide.

  Preferably, the hybrid vehicle according to the present invention further includes start means configured to generate a rotational force for starting the engine by electric power from the power storage unit, and the second lower limit value setting means is for starting the engine. The second value is determined so that the required power can be supplied from the secondary battery to the power generation means.

  Preferably, the hybrid vehicle according to the present invention further includes a power receiving unit that receives power supplied from the outside, and the control unit charges the power storage unit with external power input via the power receiving unit. Further included.

  Preferably, the shift position where generation of driving force cannot be requested includes at least one of a parking position and a neutral position.

  According to the present invention, it is possible to realize a hybrid vehicle capable of efficiently operating the engine and suppressing the total fuel consumption.

  Embodiments of the present invention will be described in detail with reference to the drawings. Note that the same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated.

FIG. 1 is a schematic configuration diagram of a hybrid vehicle according to an embodiment of the present invention.
Referring to FIG. 1, hybrid vehicle 100 according to the embodiment of the present invention includes an engine 4, motor generators MG <b> 1 and MG <b> 2, a power split mechanism 3, and wheels 2.

  Power split device 3 is mechanically coupled to engine 4 and motor generators MG1 and MG2, and distributes power between them. For example, as power split mechanism 3, a planetary gear mechanism having three rotation shafts of a sun gear, a planetary carrier, and a ring gear can be used. By these three rotating shafts, the rotating shafts of engine 4 and motor generators MG1, MG2 are mechanically coupled to each other. For example, engine 4 and motor generators MG1 and MG2 can be mechanically coupled to power split mechanism 3 by making the rotor of motor generator MG1 hollow and passing the crankshaft of engine 4 through its center.

  Note that the rotation shaft of motor generator MG2 is coupled to a drive shaft for rotationally driving wheels 2 via a reduction gear and an operation gear (not shown). Further, a reduction gear for the rotation shaft of motor generator MG2 may be further incorporated in power split device 3.

  Motor generator MG1 functions as a generator that generates electric power using the output of engine 4, or functions as an electric motor that can be started by applying a rotational force to engine 4. The motor generator MG2 functions as an electric motor that drives the wheels 2 as driving wheels to generate a driving force of the vehicle, or functions as a generator that generates electric power by receiving the rotational force of the wheels 2 during regenerative braking.

  Note that the regenerative braking mentioned here refers to power generation by turning off the accelerator pedal while the vehicle is running, although braking with power generation braking of the hybrid vehicle 100 and foot brake operation are not performed when the driver performs a foot brake operation. This includes decelerating (or stopping acceleration) while braking.

  The engine 4 is an internal combustion engine that generates an output by burning fuel, and operates according to a drive command DRV from the control device 60. Further, the engine 4 outputs an engine speed NE detected by a rotation sensor (not shown) to the control device 60.

  Furthermore, hybrid vehicle 100 according to the embodiment of the present invention can receive electric power to be supplied to motor generators MG1, MG2, and the like in addition to fuel (not shown) to be supplied to engine 4.

  Hybrid vehicle 100 includes main power storage device MB, DC converter 10, inverters 20 and 30, control device 60, capacitors C1 and C2, power supply lines PL1 and PL2, ground lines SL1 and SL2, and U-phase line. UL1, UL2, V phase lines VL1, VL2, W phase lines WL1, WL2, an input port 50, and power input lines ACL1, ACL2 are further provided.

  Main power storage device MB is a chargeable / dischargeable DC power source, and is composed of, for example, a secondary battery such as nickel metal hydride or lithium ion. Main power storage device MB supplies DC power to DC converter 10 via power supply line PL1 and ground line SL1. Main power storage device MB is charged by receiving DC power output from DC converter 10 to power supply line PL1. Note that a large-capacity electric double layer capacitor or the like may be used as the main power storage device MB.

  Capacitor C1 is connected between power supply line PL1 and ground line SL1, and smoothes voltage fluctuations between power supply line PL1 and ground line SL1.

  DC converter 10 is connected between power supply line PL1 and ground line SL1, and power supply line PL2 and ground line SL2. DC converter 10 boosts the DC voltage received from main power storage device MB based on signal PWC from control device 60, and outputs the boosted voltage to power supply line PL2. Further, DC converter 10 steps down DC voltage received from inverters 20 and 30 via power supply line PL2 to voltage level of main power storage device MB based on signal PWC from control device 60 to charge main power storage device MB. To do. The DC converter 10 is configured by, for example, a step-up / step-down chopper circuit.

  Capacitor C2 is connected between power supply line PL2 and ground line SL2, and smoothes voltage fluctuations between power supply line PL2 and ground line SL2.

  Inverters 20 and 30 are connected in parallel to power supply line PL2 and ground line SL2. Inverter 20 converts a DC voltage received from power supply line PL2 into a three-phase AC voltage based on signal PWM1 from control device 60, and outputs the converted three-phase AC voltage to motor generator MG1. Inverter 20 receives the output of engine 4 and converts the three-phase AC voltage generated by motor generator MG1 into a DC voltage based on signal PWM1 from control device 60, and the converted DC voltage is supplied to power supply line PL2. Output.

  Inverter 30 converts a DC voltage received from power supply line PL2 into a three-phase AC voltage based on signal PWM2 from control device 60, and outputs the converted three-phase AC voltage to motor generator MG2. Thereby, motor generator MG2 is driven to generate a designated torque. Further, inverter 30 converts the three-phase AC voltage generated by motor generator MG2 by receiving the rotational force from wheel 2 during regenerative braking of the vehicle into a DC voltage based on signal PWM2 from control device 60, and the conversion The DC voltage thus output is output to the power supply line PL2.

  Motor generators MG1 and MG2 are three-phase AC motors, for example, three-phase AC synchronous motors.

  Motor generator MG <b> 1 generates a three-phase AC voltage using the output of engine 4, and outputs the generated three-phase AC voltage to inverter 20. Motor generator MG <b> 1 generates driving force by the three-phase AC voltage received from inverter 20 and starts engine 4. Motor generator MG <b> 2 generates vehicle driving torque by the three-phase AC voltage received from inverter 30. Motor generator MG1 includes a Y-connected three-phase coil (not shown) as a stator coil, and is connected to inverter 20 via U, V, and W phase lines UL1, VL1, and WL1.

  On the other hand, motor generator MG2 generates a three-phase AC voltage and outputs it to inverter 30 during regenerative braking of the vehicle. Motor generator MG2 also includes a Y-connected three-phase coil (not shown) as a stator coil, and is connected to inverter 30 via U, V, and W phase lines UL2, VL2, and WL2.

  Control device 60 is configured by an ECU (Electrical Control Unit) as an example, and includes signals transmitted from each sensor including signal POS transmitted from shift position selection device 62, traveling conditions, accelerator pedal opening, main power storage device. Arithmetic processing is performed based on the SOC of the MB and the stored map. As a result, the control device 60 controls the mounted circuits and devices so that the hybrid vehicle 100 is in a desired driving state according to the operation of the driver.

  As part of such control, control device 60 generates signal PWC for driving DC converter 10 and signals PWM1 and PWM2 for driving inverters 20 and 30, respectively, and the generated signals PWC and PWM1. , PWM2 are output to DC converter 10 and inverters 20, 30 respectively.

  The shift position selection device 62 selects one of a plurality of shift positions according to the driver's operation (shift lever operation). Then, the shift position selection device 62 outputs to the control device 60 a signal POS indicating which of the plurality of shift positions selected by the driver's operation is selected. The plurality of shift positions include, for example, a parking position (P position) when the vehicle stops, a reverse position (R position) when the vehicle moves backward, a neutral position (N position), and a drive position (D position) when the vehicle moves forward. included. In addition to the drive position (D position), subdivided drive positions (for example, 4 positions, 3 positions, 2 positions, L positions, etc.) that limit the number of shiftable gear positions may be provided.

(External power acceptance configuration)
One end of power input lines ACL1 and ACL2 are connected to neutral points N1 and N2 of the three-phase coils of motor generators MG1 and MG2, respectively, and input port 50 is connected to the other ends of power input lines ACL1 and ACL2.

  The input port 50 is a power receiving unit for the hybrid vehicle 100 to receive external power from a commercial power source or the like.

  FIG. 2 is a schematic diagram of an electric power system 200 using hybrid vehicle 100 according to the embodiment of the present invention.

  Referring to FIG. 2, power system 200 includes hybrid vehicle 100 and house 150. Hybrid vehicle 100 is connected to a power outlet of house 150 by input port 50 through power input lines ACL1 and ACL2. The hybrid vehicle 100 is supplied with commercial power supplied to the house 150 via the commercial power line 55. Then, main power storage device MB of hybrid vehicle 100 is charged by a commercial power source provided from this house 150.

  Further, the hybrid vehicle 100 may be configured to supply the generated power to the house 150 via the power input lines ACL1 and ACL2. According to such a configuration, it is possible to supply electric power for operating each electrical device in the house 150 from the hybrid vehicle 100 at the time of a power failure of the commercial power source. That is, the hybrid vehicle 100 can be used as a power supply facility for the house 150.

  Referring to FIG. 1 again, input port 50 includes a relay (not shown) that operates in response to signal EN from control device 60, and power input lines ACL1, ACL2 according to signal EN. Electrical connection and disconnection from the external power supply side.

  As described above, when external power is input to hybrid vehicle 100, inverters 20 and 30 provide neutral points N1 and N2 of motor generators MG1 and MG2 from input port 50 through power input lines ACL1 and ACL2. The commercial power to be generated is converted into DC power based on signals PWM1 and PWM2 from control device 60, and the converted DC power is output to power supply line PL2.

  FIG. 3 is a zero-phase equivalent circuit of inverters 20 and 30 and motor generators MG1 and MG2 shown in FIG. Each of the inverters 20 and 30 that are three-phase inverters is composed of six transistors, and there are eight patterns of on / off combinations of the six transistors. Two of these eight patterns have zero interphase voltage, and such a voltage state is referred to as a zero voltage vector. In the zero voltage vector, the three transistors in the upper arm can be regarded as the same switching state (all on or off), and the three transistors in the lower arm can also be regarded as the same switching state. .

  Referring to FIG. 3, the three transistors in the upper arm of inverter 20 are collectively shown as upper arm 20A, and the three transistors in the lower arm of inverter 20 are collectively shown as lower arm 20B. . Similarly, the three transistors in the upper arm of the inverter 30 are collectively shown as an upper arm 30A, and the three transistors in the lower arm of the inverter 30 are collectively shown as a lower arm 30B.

  As shown in FIG. 3, this zero-phase equivalent circuit can be regarded as a single-phase PWM converter that receives AC commercial power supplied to neutral points N1 and N2 via power input lines ACL1 and ACL2. . Therefore, AC commercial power is converted to DC power by changing the zero voltage vector in each of inverters 20 and 30 and performing switching control so that inverters 20 and 30 operate as respective phase arms of single-phase PWM converters. Can be output to the power supply line PL2.

  Referring again to FIG. 1, control device 60 generates signals PWM <b> 1 and PWM <b> 2 so that the above-described zero voltage vector is generated when main power storage device MB is charged with external power, and outputs the signals to inverters 20 and 30. .

(Auxiliary load)
Hybrid vehicle 100 further includes an air conditioner device 70 and a low-pressure auxiliary machine 82.

  The air conditioner device 70 is a device for mainly cooling the interior of the hybrid vehicle 100, and includes an inverter 72 and a compressor 74. Inverter 72 converts the DC power from main power storage device MB into AC power and supplies it to compressor 74. The inverter 72 changes the voltage and frequency of the AC power supplied to the compressor 74 according to the required cooling capacity. The compressor 74 is a device that cools by using heat of vaporization by repeatedly performing compression and expansion of a refrigerant (not shown), and generates a rotational driving force using AC power supplied from the inverter 72. Compress the refrigerant with

  The low-voltage auxiliary machinery 82 is a general term for devices that operate at a low voltage (for example, 12V) compared to the output voltage of the main power storage device MB. As an example, a car navigation system, a car audio, an interior light, an interior indicator, Including.

  Such an air conditioner device 70 and the low-pressure auxiliary equipment 82 are auxiliary equipment loads for providing a comfortable in-vehicle environment to the vehicle occupant.

  As described above, since low voltage auxiliary machinery 82 operates at a lower voltage than the output voltage of main power storage device MB, hybrid vehicle 100 further includes step-down converter 80 and sub power storage device SB. Step-down converter 80 is connected to power supply lines PL1 and PL2, and steps down DC power from main power storage device MB to a predetermined DC voltage and supplies it to sub power storage device SB and low-voltage auxiliary machinery 82. The sub power storage device SB is composed of, for example, a lead storage battery, is connected to the output side of the step-down converter 80, and is charged with DC power from the step-down converter 80, while supplying the stored power to the low-voltage auxiliary machinery 82. . That is, the sub power storage device SB also functions as a power buffer for compensating for an imbalance between the output power of the step-down converter 80 and the demand power of the low-voltage auxiliary machinery 82.

  In many cases, the air conditioner device 70 and the low-pressure auxiliary devices 82 are started or stopped by an operation by a driver or the like. Then, the air conditioner device 70 and the low-pressure auxiliary machinery 82 output signals ACST and SUBST indicating the operating state at each time point to the control device 60, respectively.

(Charge / discharge control)
For the purpose of exhibiting sufficient traveling performance and the purpose of protecting main power storage device MB, control device 60 is charged so that the SOC of main power storage device MB falls within the SOC management range including a predetermined control center value. Perform discharge control.

  FIG. 4 is a diagram illustrating an example of charge / discharge control by the control device 60. In FIG. 4, S1 <S2 <S3 <S4 holds.

  Referring to FIG. 4, control device 60 limits the discharge power from main power storage device MB when main power storage device MB is close to an overdischarged state and the SOC is lower than state value S2. Furthermore, when SOC falls below state value S1, control device 60 prohibits discharging from main power storage device MB.

  Control device 60 limits charging power to main power storage device MB when main power storage device MB is close to an overcharged state and the SOC exceeds state value S3. Further, when the SOC exceeds state value S4, control device 60 prohibits charging of main power storage device MB.

  Note that various well-known techniques can be used for the configuration for acquiring the SOC of the main power storage device MB, and a detailed description thereof in this embodiment will be omitted.

  When main power storage device MB is not charged by external power (input port 50 is not connected to the power outlet of house 150), the power for charging main power storage device MB receives the output of engine 4. Power generated by the motor generator MG1 and power from the motor generator MG2 generated during regeneration.

  However, since regenerative braking occurs according to the operation of the driver, it cannot be expected as electric power for reliably charging main power storage device MB. Therefore, control device 60 determines that SOC of main power storage device MB is a predetermined lower limit determination value (for example, state value S2 in FIG. 4, hereinafter also referred to as “SOC lower limit value”) when engine 4 is maintained in a stopped state. If it falls below, the engine 4 is forcibly started to increase the charge amount of the main power storage device MB.

  In a typical hybrid vehicle, even if the driver gets on and turns on the ignition key, the engine does not start immediately, depending on when the vehicle exceeds a predetermined vehicle speed or when the accelerator pedal is depressed by the driver. When a predetermined driving force is requested, the engine is started. Therefore, after the driver has boarded and turned on the ignition key, the air conditioner device 70 and the low-pressure auxiliary equipment 82 are operated for a long period of time without starting the vehicle. Is continuously discharged from the main power storage device MB. When the SOC lower limit value of main power storage device MB falls below, control device 60 provides drive command DRV to engine 4 to start engine 4 and starts charging main power storage device MB with electric power generated by motor generator MG1. To do.

  Since the amount of power generated by motor generator MG1 is smaller than the maximum output of engine 4, when only power generation by motor generator MG1 is performed, engine 4 is operated in a rotational speed range where combustion efficiency is relatively low. I had to. As a result, there is a problem that the fuel consumption increases when viewed comprehensively.

  Further, since the engine 4 is operated while the hybrid vehicle 100 is stopped, there is a problem that comfort for passengers including the driver is impaired and noise is generated in the vicinity.

  Therefore, control device 60 in hybrid vehicle 100 according to the embodiment of the present invention sets the SOC lower limit value of main power storage device MB which is the starting condition of engine 4 only when the driving force by motor generator MG2 cannot be requested. Change to a lower value. That is, when generation of driving force from motor generator MG2 cannot be requested, the discharge power from main power storage device MB is limited to a relatively small load such as air conditioner device 70 and low-voltage auxiliary machinery 82. Therefore, control device 60 changes the SOC lower limit value for protecting main power storage device MB from overdischarge according to the presence or absence of a driving force generation request from motor generator MG2.

  Specifically, control device 60 determines which of a plurality of shift positions is selected based on signal POS from shift position selection device 62, and from motor generator MG2 such as a parking position or a neutral position. When the shift position at which generation of the driving force cannot be requested is selected, the SOC lower limit value of main power storage device MB for starting engine 4 is changed to a lower value.

  Further, control device 60 determines an SOC lower limit value corresponding to the operating state based on signals ACST and SUBST transmitted from air conditioner device 70 and low-pressure auxiliary devices 82, respectively. That is, the power consumption required by the air conditioner device 70 and the low-pressure auxiliary equipment 82 is calculated. If the power consumption is large, the SOC lower limit value is relatively increased. If the power consumption is small, the SOC lower limit value is relatively increased. To lower.

FIG. 5 is a diagram illustrating an example of a temporal change in the SOC lower limit value by the control device 60.
Referring to FIG. 5, control device 60 sets the SOC lower limit value to normal value LLIM when the drive position (D position) or reverse position (R position) is selected. On the other hand, when the parking position (P position) or neutral position (N position) is selected, control device 60 sets the SOC lower limit value to a lower relaxation value #LLIM (#LLIMa or #LLIMb). Further, for example, if air conditioner device 70 is in operation, control device 60 sets the SOC lower limit value to a relaxation value #LLIMb. If air conditioner device 70 is not in operation, the control device 60 sets the SOC lower limit value more. Set to a low relaxation value #LLIMa. Note that normal value LLIM> relaxation value #LLIMb> relaxation value #LLIMb.

  Generally, since the ignition key is turned on while the parking position (P position) is selected, immediately after the ignition key is turned on, the control device 60 reduces the SOC lower limit to the relaxation value #LLIMa. Change to After that, when the driver or the like turns on the air conditioner device 70, the control device 60 sets the SOC lower limit value to the relaxation value #LLIMb. Then, when the driver selects a drive position (D position) to start the vehicle, control device 60 returns the SOC lower limit value to normal value LLIM. Furthermore, when the driver selects the parking position (P position) again after the vehicle stops, control device 60 changes the SOC lower limit value to relaxation value #LLIMa. In the case where the drive position (D position) is selected, control device 60 sets the SOC lower limit value to normal value LLIM regardless of the operating conditions of air conditioner device 70 and low-pressure auxiliary machinery 82. Therefore, even if the air conditioner device 70 is turned off while the drive position (D position) is selected, the control device 60 maintains the SOC lower limit value being set.

  In FIG. 5, for convenience of explanation, an example in which the relaxation value #LLIM is switched to two stages (#LLIMa or #LLIMb) according to whether the air conditioner device 70 is turned on or off has been described. The relaxation value #LLIM may be changed in the number of steps or steplessly.

  In hybrid vehicle 100 according to the embodiment of the present invention, electric power from main power storage device MB is supplied to motor generator MG1, and engine 4 is rotationally driven (cranked) by the rotational force generated by motor generator MG1. To start the engine 4. Therefore, control device 60 determines relaxation value #LLIM so that motor generator MG1 can supply power required for cranking of engine 4 from main power storage device MB. As an example, the SOC corresponding to the charged state obtained by adding the power required for cranking by motor generator MG1 to the charged state at state value S1 that is the boundary of the discharge prohibited region shown in FIG. And That is, control device 60 determines relaxation value #LLIM so that the SOC of main power storage device MB does not reach the discharge prohibited region immediately after engine 4 is started. Instead of the configuration in which the engine 4 is cranked by the motor generator MG1, a starter composed of a cell motor or the like that is used exclusively for starting the engine 4 may be provided.

(Control flow)
FIG. 6 is a flowchart relating to starting of the engine 4 in the control device 60.

  Referring to FIG. 6, control device 60 determines whether or not engine 4 is operating based on engine speed NE transmitted from engine 4 (step S100).

  If engine 4 is operating (YES in step S100), control device 60 ends the subsequent processing.

  When engine 4 is not in operation (NO in step S100), control device 60 selects a shift position selected from a plurality of shift positions based on signal POS transmitted from shift position selection device 62. Is acquired (step S102). Further, control device 60 determines whether or not the acquired shift position is a parking position (P position) or a neutral position (N position), which is a shift position where the driving force by motor generator MG2 cannot be requested ( Step S104).

  When the acquired shift position is the parking position (P position) or the neutral position (N position) (YES in step S104), control device 60 transmits from air conditioner device 70 and low-pressure auxiliary machinery 82. Based on the received signals ACST and SUBST, relaxation value #LLIM is calculated (step S106). Then, control device 60 sets calculated relaxation value #LLIM as the SOC lower limit value (step S108).

  On the other hand, when the acquired shift position is a drive position (D position) or a reverse position (R position) and is not a parking position (P position) or a neutral position (N position) (NO in step S104). Then, control device 60 sets normal value LLIM to the SOC lower limit value (step S110).

  After the SOC lower limit value is set (step S108 or S110), control device 60 acquires the SOC of main power storage device MB (step S112). Then, control device 60 determines whether or not the acquired SOC is below the SOC lower limit value (step S114).

  When the obtained SOC is lower than the SOC lower limit value (YES in step S114), control device 60 generates signal PWM1 for cranking engine 4 and outputs it to inverter 20, and at the same time, engine The drive command DRV is output to 4, and the engine 4 is started (step S116). In other words, inverter 20 receives signal PWM1 from control device 60 and generates drive force from motor generator MG1, while engine 4 receives drive command DRV from control device 60 and starts fuel injection and ignition.

  If the acquired SOC is not lower than the SOC lower limit value (NO in step S114), control device 60 ends the subsequent processing.

(Application example)
FIG. 7 is a time waveform of each part in the conventional charge / discharge control. FIG. 7 shows a case where the parking position (P position) is selected for a relatively long time before starting the vehicle and after traveling.

FIG. 7A shows the SOC of main power storage device MB.
FIG. 7B shows the charge / discharge current of main power storage device MB.

FIG. 7C shows the rotational speed of the engine 4.
With reference to FIGS. 7A and 7B, as an example, in the state ST1 in which the parking position (P position) is selected, the load current by the air conditioner device 70 and the low-pressure auxiliary machinery 82 is constant. If so, the discharge current from main power storage device MB is also constant, and the SOC of main power storage device MB gradually decreases in accordance with this discharge current. Then, when the SOC of main power storage device MB falls below normal value LLIM (time T1), engine 4 is started as shown in FIG. At this time, the engine 4 operates in the low combustion efficiency region 90.

  Thereafter, when the drive position (D position) is selected (state ST2) and the driver depresses the accelerator pedal to start the hybrid vehicle 100, the charge / discharge amount of the main power storage device MB as shown in FIG. 7B. Changes according to the driver's operation and the driving situation. Moreover, as shown in FIG.7 (c), the engine 4 is operated intermittently according to a driving | running condition so that high combustion efficiency can be maintained. As a result, as shown in FIG. 7A, the SOC of main power storage device MB is controlled within a predetermined SOC management range.

  If the parking position (P position) is selected after traveling (state ST3), the engine 4 is stopped. Then, as in state ST1, the SOC of main power storage device MB gradually decreases in accordance with the discharge current from main power storage device MB. When the SOC of main power storage device MB again falls below normal value LLIM (time T2), engine 4 is started again as shown in FIG. 7C. Also at this time, the engine 4 operates in the low combustion efficiency region 91.

  As described above, in the conventional charge / discharge control, the engine 4 has to operate in the low combustion efficiency regions 90 and 91.

  FIG. 8 is a time waveform of each part in the charge / discharge control according to the embodiment of the present invention when the same running pattern as in FIG. 7 is performed.

FIG. 8A shows the SOC of main power storage device MB.
FIG. 8B shows the charge / discharge current of main power storage device MB.

FIG. 8C shows the rotational speed of the engine 4.
Referring to FIGS. 8A and 8B, control device 60 sets the SOC lower limit value to relaxation value #LLIM while parking position (P position) is being selected (state ST1). Compared to the charge / discharge control, the time until the engine 4 is started can be made longer. Therefore, as shown in FIG. 8C, even when the state ST1 continues for a long period of time, the stopped state of the engine 4 is maintained.

  Thereafter, when the drive position (D position) is selected (state ST2), control device 60 returns the SOC lower limit value to normal value LLIM, so that if the SOC of main power storage device MB is lower than LLIM, engine 4 is started. Around that time, when the accelerator pedal is depressed by the driver, the output of the engine 4 is used as the charge of the main power storage device MB and the driving force of the vehicle. Hereinafter, in the state ST2, a charge / discharge control process similar to the conventional one is executed.

  When the parking position (P position) is selected after traveling (state ST3), the engine 4 is stopped or maintained in the stopped state. Then, similarly to state ST1, control device 60 sets the SOC lower limit value to relaxation value #LLIM, so that the time until engine 4 is restarted is longer than in the case of conventional charge / discharge control. can do. Further, when the driver turns off the ignition key before the SOC lower limit value falls below the relaxation value #LLIM, the engine 4 is not restarted.

  Thus, in the charge / discharge control according to the embodiment of the present invention, the region where the engine 4 operates with low combustion efficiency can be avoided, so that the engine 4 can be operated efficiently and the fuel consumption can be suppressed. it can.

  Furthermore, in hybrid vehicle 100 according to the embodiment of the present invention, main power storage device MB can be charged with external power. Therefore, when the driver or the like performs external charging after traveling (state ST4), even if the SOC of main power storage device MB is reduced to the vicinity of relaxation value #LLIM, main power storage device MB is in the next travel ( The battery is charged up to the vicinity of the SOC upper limit by the next ignition ON).

  Generally, since a commercial power source is generated by a large power plant, even if transport loss (loss in a transformer or transmission line) is taken into consideration, it is compared with the case where power is generated using the output of the engine 4. , Combustion efficiency can be increased. Therefore, from the viewpoint of reducing the environmental impact, it is desirable to increase the use efficiency of the commercial power source with less fuel for generating the same amount of power.

  As described above, in hybrid vehicle 100 according to the embodiment of the present invention, the frequency of engine operation in a region with relatively poor combustion efficiency can be further reduced by using a commercial power source stored in advance. Thereby, the comprehensive combustion efficiency which concerns on vehicle travel can be raised, and the influence on an environment can be reduced more.

  FIG. 9 is a schematic diagram showing the relationship between the power consumption and the fuel consumption rate. The fuel consumption rate indicates the amount of fuel (or fuel cost) required to generate unit power. Therefore, the area defined by the vertical axis and the horizontal axis indicates the amount of fuel required to generate the corresponding amount of power.

FIG. 9A shows the case of conventional charge / discharge control.
FIG. 9B shows a case of charge / discharge control (without external charging) according to the embodiment of the present invention.

  FIG. 9C shows the case of charge / discharge control (with external charge) according to the embodiment of the present invention.

  With reference to FIG. 9A, as described above, in the conventional charge / discharge control, when the operation of the air conditioner device 70 and the low-pressure auxiliary machinery 82 continues while the vehicle is stopped, the engine 4 has a low combustion efficiency. It was forced to operate in areas 90 and 91. Therefore, even if the engine 4 is operated in the high combustion efficiency region 92 during traveling, the total fuel consumption (the total area of the regions 90 and 91 and the region 92) is relatively large.

  With reference to FIG. 9 (b), according to the charge / discharge control according to the embodiment of the present invention, even if the operation of the air conditioner device 70 and the low-pressure auxiliary machinery 82 continues during the stop, the engine 4 is stopped. It is possible to avoid operating in the low combustion efficiency region. Therefore, the fuel consumption in the low combustion efficiency regions 90 and 91 can be suppressed to the fuel consumption in the high combustion efficiency region 92 as compared with the conventional charge / discharge control shown in FIG.

  Referring to FIG. 9 (c), by performing external charging further, external power having a lower fuel consumption rate can be used in place of the power generated by the output from engine 4. As a result, as compared with FIG. 9B, the fuel consumption is corresponding to the difference in fuel consumption rate between the high combustion efficiency region 92 of the engine 4 and the external charge 93 and the amount of power charged by the external charge 93. The amount can be suppressed.

  In the above description, the case where the present invention is applied to a hybrid vehicle that can charge main power storage device MB with external power has been described. However, this is a hybrid vehicle that cannot charge main power storage device MB with external power. However, it goes without saying that the effects of the present invention can be exhibited.

  In the embodiment of the present invention, the motor generators MG1 and MG2 can realize “power generation means” or “electric power generation means”. However, in many situations, the motor generator MG1 realizes “power generation means”. Motor generator MG2 realizes “electric power generation means”. Furthermore, motor generator MG1 implements “power generation means”. The main power storage device MB corresponds to the “power storage unit”, the control device 60 corresponds to the “control unit”, the air conditioner device 70 and the low-voltage auxiliary machinery 82 correspond to “auxiliary load”, and the input port 50 and the power input lines ACL1 and ACL2 correspond to the “power receiving unit”.

  According to the embodiment of the present invention, when a shift position (parking position or neutral position) where generation of driving force from motor generator MG2 cannot be requested is selected, that is, relatively large electric power is supplied from main power storage device MB. Is not required to be output, control device 60 changes the SOC lower limit value, which is the starting condition of engine 4, from normal value LLIM to a lower relaxation value #LLIM. Therefore, even when the air conditioner device 70 and the low-pressure auxiliary machinery 82 are operating for a relatively long time while the engine 4 is stopped, the engine 4 is used to charge the main power storage device MB. The frequency of starting can be reduced.

  Therefore, the operation of the engine 4 in the region where the combustion efficiency for charging the main power storage device MB is relatively poor can be suppressed, and the total fuel consumption can be suppressed.

  Furthermore, the vibration and noise associated with the starting and operation of the engine 4 while the vehicle is stopped (parking) further impairs the comfort of the passenger as compared with the traveling with relatively large vibration and noise associated with the traveling. Therefore, according to the embodiment of the present invention, since the start frequency of the engine 4 during stopping (parking) can be reduced, it is possible to provide more comfort (quietness) to the passenger. At the same time, it is possible to suppress the generation of noise in the vicinity while the vehicle is parked.

  In the embodiment of the present invention, the application example to the series / parallel hybrid system in which the power of the engine is divided into the drive shaft and the motor generator (generator) by the power split mechanism is shown. However, the present invention can also be applied to a series hybrid vehicle that uses the output of the engine only to drive the generator and generates the driving force of the vehicle using only the motor that uses the electric power generated by the generator. In any of these configurations, the drive shaft and the motor or the generator are connected, and the present invention can be applied because the regenerative energy at the time of deceleration can be recovered and stored in the battery.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a schematic configuration diagram of a hybrid vehicle according to an embodiment of the present invention. It is the schematic of the electric power system using the hybrid vehicle according to embodiment of this invention. 2 is a zero-phase equivalent circuit of the inverter and motor generator shown in FIG. 1. It is a figure which shows an example of charging / discharging control by a control apparatus. It is a figure which shows an example of the time change of SOC lower limit by a control apparatus. It is a flowchart which concerns on starting of the engine in a control apparatus. It is a time waveform of each part in the conventional charge / discharge control. It is a time waveform of each part in the charge / discharge control which concerns on embodiment of this invention at the time of performing the driving | running | working pattern similar to FIG. It is a schematic diagram which shows the relationship between power consumption and a fuel consumption rate.

Explanation of symbols

  2 wheel, 3 power split mechanism, 4 engine, 6 shift position selection device, 10 DC converter, 12 voltage value detection unit, 14 current value detection unit, 20, 30, 72 inverter, 20A, 30A upper arm, 20B, 30B lower Arm, 50 input port, 55 Commercial power line, 60 Control device, 62 Shift position selection device, 70 Air conditioner device, 74 Compressor, 80 Step-down converter, 82 Low pressure auxiliary equipment, 90, 91 Low combustion efficiency region, 92 High combustion efficiency range, 93 external charging, 100 hybrid vehicle, 150 housing, 200 power system, ACL1, ACL2 power input line, ACST, SUBST signal, C1, C2 capacitor, DRV drive command, EN signal, Ib voltage value, LLIM Normal Value, #LLIM relaxation value, MB Main power storage device, MG1, MG2 motor generator, N1, N2 neutral point, NE engine speed, PL1, PL2 power line, POS signal, PWC, PWM1, PWM2 signal, SB sub power storage device, SL1, SL2 ground line, UL1 , UL2, VL1, VL2, WL1, WL2 phase line, Vb voltage value.

Claims (5)

Engine,
Power generation means mechanically coupled to the engine and generating power using the output of the engine;
A power storage unit configured to be rechargeable by the power generated by the power generation means;
An electric force generating means that is mechanically coupled to a driving shaft of the vehicle and generates driving force of the vehicle using electric power from the power storage unit;
A control unit that starts the engine to supply charging power of the power storage unit by the power generation means when a state value indicating a charging state of the power storage unit is lower than a lower limit determination value;
The controller is
Shift position determining means for determining which one of a plurality of shift positions is selected by the operation of the driver;
When the shift position determining means determines that a shift position that can require generation of driving force from the electric force generating means is selected, the lower limit determination value is set to the first value. Lower limit value setting means,
When it is determined by the shift position determination means that a shift position that cannot be requested to generate a driving force from the electric force generation means is selected, the lower limit determination value is set to a second value lower than the first value. And a second lower limit setting means for setting the value to a hybrid vehicle. An auxiliary machine load that operates with electric power from the power storage unit,
2. The hybrid vehicle according to claim 1, wherein the second lower limit value setting means determines the second value in accordance with an operating state of the auxiliary machine load. Further comprising a starting means configured to generate a rotational force for starting the engine by the electric power from the power storage unit;
3. The hybrid according to claim 1, wherein the second lower limit value setting unit determines the second value so that electric power required for starting the engine is supplied from the secondary battery to the power generation unit. vehicle. It further includes a power receiving unit that receives power supplied from the outside,
The hybrid vehicle according to claim 1, wherein the control unit further includes a charge control unit that charges the power storage unit with external power input via the power receiving unit.   The hybrid vehicle according to any one of claims 1 to 4, wherein the shift position where generation of driving force cannot be requested includes at least one of a parking position and a neutral position.

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