WO2014102600A1 - Hybrid vehicle, warm-up control device for hybrid vehicle, and warm-up control method for hybrid vehicle - Google Patents

Hybrid vehicle, warm-up control device for hybrid vehicle, and warm-up control method for hybrid vehicle Download PDF

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Publication number
WO2014102600A1
WO2014102600A1 PCT/IB2013/002966 IB2013002966W WO2014102600A1 WO 2014102600 A1 WO2014102600 A1 WO 2014102600A1 IB 2013002966 W IB2013002966 W IB 2013002966W WO 2014102600 A1 WO2014102600 A1 WO 2014102600A1
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WO
WIPO (PCT)
Prior art keywords
engine
heat
lubricant
temperature
exchange device
Prior art date
Application number
PCT/IB2013/002966
Other languages
French (fr)
Inventor
Keisuke OMURO
Atsushi Tabata
Tooru Matsubara
Tatsuya Imamura
Takeshi Kitahata
Kenta Kumazaki
Yasuhiro Hiasa
Kouichi Okuda
Masafumi Yamamoto
Keita Imai
Original Assignee
Toyota Jidosha Kabushiki Kaisha
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toyota Jidosha Kabushiki Kaisha filed Critical Toyota Jidosha Kabushiki Kaisha
Publication of WO2014102600A1 publication Critical patent/WO2014102600A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K6/00—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00
    • B60K6/20—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs
    • B60K6/42—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs characterised by the architecture of the hybrid electric vehicle
    • B60K6/44—Series-parallel type
    • B60K6/445—Differential gearing distribution type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/04—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
    • B60W10/06—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units including control of combustion engines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W20/00—Control systems specially adapted for hybrid vehicles
    • B60W20/10—Controlling the power contribution of each of the prime movers to meet required power demand
    • B60W20/15—Control strategies specially adapted for achieving a particular effect
    • B60W20/16—Control strategies specially adapted for achieving a particular effect for reducing engine exhaust emissions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
    • B60W30/18—Propelling the vehicle
    • B60W30/192—Mitigating problems related to power-up or power-down of the driveline, e.g. start-up of a cold engine
    • B60W30/194—Mitigating problems related to power-up or power-down of the driveline, e.g. start-up of a cold engine related to low temperature conditions, e.g. high viscosity of hydraulic fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02N—STARTING OF COMBUSTION ENGINES; STARTING AIDS FOR SUCH ENGINES, NOT OTHERWISE PROVIDED FOR
    • F02N19/00—Starting aids for combustion engines, not otherwise provided for
    • F02N19/02—Aiding engine start by thermal means, e.g. using lighted wicks
    • F02N19/04—Aiding engine start by thermal means, e.g. using lighted wicks by heating of fluids used in engines
    • F02N19/10—Aiding engine start by thermal means, e.g. using lighted wicks by heating of fluids used in engines by heating of engine coolants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2510/00—Input parameters relating to a particular sub-units
    • B60W2510/06—Combustion engines, Gas turbines
    • B60W2510/0676—Engine temperature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2510/00—Input parameters relating to a particular sub-units
    • B60W2510/08—Electric propulsion units
    • B60W2510/087—Temperature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2510/00—Input parameters relating to a particular sub-units
    • B60W2510/10—Change speed gearings
    • B60W2510/107—Temperature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2510/00—Input parameters relating to a particular sub-units
    • B60W2510/24—Energy storage means
    • B60W2510/242—Energy storage means for electrical energy
    • B60W2510/244—Charge state
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/62—Hybrid vehicles

Definitions

  • HYBRID VEHICLE WARM-UP CONTROL DEVICE FOR HYBRID VEHICLE, AND WARM-UP CONTROL METHOD FOR HYBRID VEHICLE
  • the invention relates to a vehicle, a control device for the vehicle, and a control method for the vehicle, and more particularly relates to warm-up control of an internal combustion engine in a vehicle having a rotary electric machine and the internal combustion engine as drive sources.
  • a hybrid vehicle on which an internal combustion engine (such as an engine) and an electric motor are installed as vehicle power sources is known.
  • the hybrid vehicle may preferentially run in an electrically powered running mode (which will also be called “EV (Electric Vehicle) running mode”), using only the output of the electric motor while stopping the operation of the engine, in order to improve the fuel economy.
  • EV Electrical Vehicle
  • JP 2009-120043 A discloses a vehicle including an operating mechanism to which first and second rotary electric machines and an engine are coupled, and a clutch for fixing a rotary shaft of the engine.
  • the clutch is arranged to fix the rotary shaft of the engine when the vehicle runs in the EV running mode.
  • the engine may be started in a condition where the engine is not sufficiently warmed up. In this condition, the combustion efficiency of the engine may be reduced, and emissions may deteriorate.
  • HV Hybrid Vehicle
  • the invention provides a vehicle, which is a hybrid vehicle having an internal combustion engine and a rotary electric machine as drive sources, in which the internal combustion engine can be appropriately warmed up when the vehicle switches from the EV running mode to the HV running mode.
  • the invention also provides a control device for the vehicle, and a control method for the vehicle.
  • a vehicle includes an engine, a drive-train including a first rotary electric machine that operates as a drive source, a heat-exchange device configured to effect heat exchange between a lubricant used in the drive-train and a cooling medium used in the engine, and a control device.
  • the control device is configured to activate the heat-exchange device so as to warm up the engine when the engine is expected to be started while the vehicle is running using driving force from the first rotary electric machine.
  • the vehicle may further include a power storage device configured to supply electric power for driving the first rotary electric machine.
  • the control device may activate the heat-exchange device when a state of charge of the power storage device is lower than a given reference value. Also, when the state of charge of the power storage device is lower than the given reference value, the control device may determine that the engine is expected to be started, and activate the heat-exchange device.
  • the control device may keep the heat-exchange device in a non-activated state even in the case where the engine is expected to be started.
  • control device may keep the heat-exchange device in a non-activated state even in the case where the engine is expected to be started.
  • the control device may activate the heat-exchange device when a temperature difference obtained by subtracting a temperature of the cooling medium from a temperature of the lubricant is larger than a predetermined threshold value.
  • the drive-train may further include a second rotary electric machine, and a differential device including a first rotary element, a second rotary element, and a third rotary element.
  • the first rotary electric machine is coupled to the first rotary element
  • the second rotary electric machine is coupled to the second rotary element
  • the engine is coupled to the third rotary element.
  • the control device may drive both the first rotary electric machine and the second rotary electric machine so as to warm the lubricant when a temperature of the lubricant is lower than a given reference temperature.
  • the drive-train may further include . an engaging element that suppresses rotation of the third rotary element, and a transmission provided between the second rotary element and the drive wheels.
  • the control device may activate the heat-exchange device so as to warm the lubricant by use of the cooling medium.
  • the vehicle may further include a switching portion provided in a flow channel of the lubricant that flows into the heat-exchange device and configured to switch between a first position in which the lubricant is allowed to flow into the heat-exchange device and a second position in which the lubricant is inhibited from flowing into the heat-exchange device.
  • the control device may activate the heat-exchange device, by controlling the switching portion so as to cause the lubricant to flow into the heat-exchange device.
  • a second aspect of the invention provides a control device for a vehicle including an engine, a drive-train including a rotary electric machine that operates as a drive source, and a heat-exchange device configured to effect heat exchange between a lubricant used in the drive-train and a cooling medium used in the engine.
  • the control device includes a determining unit configured to determine whether the engine is expected to be started while the vehicle is running using driving force from the rotary electric machine, and a controller configured to activate the heat-exchange device so as to warm up the engine in response to a determination that the engine is expected to be started.
  • a third aspect of the invention provides a control method for a vehicle including an engine, a drive-train including a rotary electric machine that operates as a drive source, and a heat-exchange device configured to effect heat exchange between a lubricant used in the drive-train and a cooling medium used in the engine.
  • the control method includes the steps of: determining whether the engine is expected to be started while the vehicle is running using driving force from the rotary electric machine, and activating the heat-exchange device so as to warm up the engine in response to a determination that the engine is expected to be started.
  • the internal combustion engine in the hybrid vehicle having the internal combustion engine and the rotary electric machine as drive sources, can be warmed up before it is started, when the vehicle switches from the EV running mode to the HV running mode.
  • FIG. 1 is an overall block diagram of a vehicle according to one embodiment of the invention
  • FIG. 2 is a functional block diagram useful for explaining warm-up control executed by ECU in the embodiment of FIG. 1;
  • FIG. 3 is a flowchart useful for explaining details of a warm-up control routine executed by the ECU in the embodiment of FIG. 1;
  • FIG. 4 is a view showing a first example of map that defines reference temperatures used for determining whether a heat-exchange device can be activated
  • FIG. 5 is a view showing a- second example of map that defines reference temperatures used for determining whether a heat-exchange device can be activated
  • FIG. 6 is a flowchart useful for explaining details of a warm-up control routine according to a first modified example of the embodiment of FIG. 1 ;
  • FIG 7 is a flowchart useful for explaining details of a warm-up control routine according to a second modified example of the embodiment of FIG. 1.
  • FIG. 1 is an overall block diagram of a vehicle 100 according to one embodiment of the invention.
  • the vehicle 100 includes a power storage device 110, a PCU (Power Control Unit) as a drive unit, an engine 130 as an internal combustion engine, a drive-train 200, a speed reducer 140, drive wheels 150, a heat-exchange device 160, and an ECU (Electronic Control Unit) 300 as a control device.
  • PCU Power Control Unit
  • the PCU 120 includes a converter 121 and inverters 122, 123.
  • the drive-train 200 includes motor-generators 210 (MG1), 220 (MG2), a differential device 230, an engaging device 240, and an automatic transmission (A/T) 250 (which will also be simply called "transmission").
  • the power storage device 110 is an electric power storage element configured to be able to be charged with electric power and discharge electric power.
  • the power storage device 110 includes a power storage element, which may be a secondary battery, such as a lithium-ion battery, nickel-metal-hydride battery, or a lead storage battery, or an electric double layer capacitor.
  • the power storage device 110 is electrically coupled to the converter 121 in the PCU 120.
  • the power storage device 110 supplies electric power for generating driving force of the vehicle 100, to the PCU 120.
  • the power storage device 110 stores electric power generated by the motor-generators 210, 220.
  • the output of the power storage device 110 is about 200V, for example.
  • the power storage device 110 is provided with a voltage sensor, a current sensor, and a temperature sensor, all of which are not shown in the drawings.
  • the ECU 300 receives a value of voltage VB of the power storage device 110 detected by the voltage sensor, a value of current IB that flows into and out of the power storage device 110, which is detected by the current sensor, and a temperature TB of the power storage device 110 detected by the temperature sensor.
  • the converter 121 boosts the voltage of the power storage device 110, based on a control signal PWC from the ECU 300, and supplies the voltage to the inverters 122, 123. Also, the converter 121 steps down the voltage generated by the motor-generators 210, 220 and rectified by the inverters 122, 123, and charges the power storage device 110 with the resulting power.
  • the inverters 122, 123 are connected in parallel with each other, as seen from the converter 121.
  • the inverters 122, 123 convert DC (direct-current) power supplied from the converter 121, into AC (alternating-current) power, and drive the motor-generators 210, 220, respectively, based on control signals PWl l, PW12 received from the ECU 300.
  • Each of the motor-generators 210, 220 is an AC rotary electric machine, such as a permanent-magnet-type synchronous motor including a rotor in which a permanent magnet is embedded.
  • the motor-generators 210, 220 and the engine 130 are coupled to each other by a differential device 230.
  • the differential device 230 includes a planetary gear mechanism.
  • the motor-generator 210 is coupled to a sun gear S of the planetary gear mechanism, and the engine 130 is coupled to a planetary carrier C of the planetary gear mechanism, while the motor-generator 220 is coupled to a ring gear R of the planetary gear mechanism.
  • the engine 130 is controlled according to a control signal DRV received from the ECU 300.
  • the motor-generators 210, 220 and the engine 130 are operated by the ECU 300 in a coordinated manner, so as to generate required vehicle driving force.
  • the vehicle 100 is able to run in a so-called EV running mode, using only the driving force from the motor-generators 210, 220, while the engine 130 is being stopped.
  • the differential device 230 which is arranged to be coupled with the engine 130 and the motor-generators 210, 220, also functions as a continuously variable transmission.
  • An output shaft of the motor-generator 220 is coupled to an input shaft of the automatic transmission 250.
  • An output shaft of the automatic transmission 250 is coupled to the drive wheels 150 via a speed reducer 140.
  • the automatic transmission 250 is controlled according to a control signal SFT received from the ECU 300, so as to change the speed ratio between the motor-generator 220 and the drive wheels 150.
  • the automatic transmission 250 may be a stepwise variable transmission for which a plurality of different fixed speed ratios are set in advance, or a continuously variable transmission capable of continuously change the speed ratio.
  • the engaging device 240 typically takes the form of a clutch or a brake.
  • the engaging device 240 is controlled according to a control signal SIG received from the ECU 300, so as to fix an output shaft of the engine 130 when it is placed in an engaged state. While the vehicle is running in the EV running mode, the engaging device 240 fixes the output shaft of the engine 130, so that the driving force of both of the motor-generators 210, 220 can be transmitted to the drive wheels 150. At this time, rotation of the engine 130 is suppressed, . so that a mechanical transmission loss that would be caused by rotation of the rotary shaft of the engine 130 can be reduced.
  • a speed sensor 180 for detecting the rotational speed of the drive wheels 150, or the vehicle speed, is provided in the vicinity of the drive wheel 150.
  • the speed sensor 180 outputs a speed value VS thus detected, to the ECU 300. While the speed sensor 180 is located in the vicinity of the drive wheel 150 in this embodiment of FIG 1, the location of the speed sensor 180 is not limited to this, but the speed sensor 180 may be located in the vicinity of a driven wheel (not shown), or may be located in the vicinity of the output shaft of the drive-train 200. If the vehicle speed can be obtained by calculation, from the rotational speed of the motor-generator 220 and the speed ratio of the automatic transmission 250, for example, the speed sensor may be omitted.
  • the heat-exchange device 160 (which will also be called “warmer”) includes a pipe 161 as a part of a channel through which a lubricant (ATF) for lubricating the interior of the drive-train 200 flows, and a pipe 162 as a part of a channel through which a cooling medium (e.g., a coolant) for cooling the engine 130 flows.
  • ATF lubricant
  • the pipes 161, 162 are located close to each other or in contact with each other, and heat exchange takes place between the lubricant and the coolant when there is a temperature difference between the lubricant flowing through the pipe 161 and the coolant flowing through the pipe 162.
  • a switching valve 170 as a switching portion is provided in a portion of the pipe 161 through which the lubricant flows from the drive-train 200 into the heat-exchange device 160.
  • the switching valve 170 is controlled according to a control signal ST received from the ECU 300, so as to be placed in a selected one of a communicating position in which the lubricant is allowed to flow from the drive-train 200 into the heat-exchange device 160, and a non-communicating position in which the lubricant is inhibited from flowing from the drive-train 200 into the heat-exchange device 160.
  • a temperature sensor 260 for detecting the temperature of the lubricant is provided at around a location where the lubricant flows into the pipe 161.
  • the temperature sensor 260 outputs the detected temperature TF of the lubricant to the ECU 300. While the temperature sensor 260 is provided inside the drive-train 200 in the embodiment of FIG. 1, the temperature sensor 260 may be provided outside the drive-train 200, more specifically, in a channel that extends from the drive-train 200 to the switching valve 170.
  • a temperature sensor 135 for detecting the temperature of the coolant is provided at around a location where the coolant flows into the pipe 162.
  • the temperature sensor 135 outputs the detected temperature TW of the coolant to the ECU 300.
  • the temperature sensor 135 may also be provided outside the erigine 130, more specifically, in a channel that extends from the engine 130 to the heat-exchange device 160.
  • the ECU 300 includes a CPU (Central Processing Unit), a storage device and input and output buffers, all of which are not shown in FIG. 1, and is configured to receive signals from respective sensors, etc. and transmit control signals to respective devices, so as to control the vehicle 100 and respective devices.
  • the control of the vehicle 100 and its devices is not limited to processing by software, but may be implemented by dedicated hardware (electronic circuits).
  • the ECU 300 receives detected values of the voltage VB, current IB and temperature IB from the power storage device 110.
  • the ECU 300 calculates the state of charge (which will also be called "SOC") of the power storage device 110, based on these pieces of information.
  • the ECU 300 receives the rotational speed NE of the engine 130 from the engine 130.
  • the ECU 300 also receives the rotational speeds NM1, NM2 and temperatures TM1, TM2 of the respective motor-generators 210, 220.
  • the ECU 300 receives a signal ACC indicative of an accelerator pedal position from the accelerator pedal 190, and calculates required power based on the signal ACC.
  • the ECU 300 also calculates torque to be produced by the engine 130 and the motor-generators 210, 220.
  • the ECU 300 receives a signal POS indicative of a shift position from a shift lever 195, and controls the engine 130, motor-generators 210, 220, and the automatic transmission 250, based on the signal POS.
  • control device While one control device is provided as the ECU 300 in the embodiment of FIG 1 , individual control devices for respective functions or respective devices to be controlled, such as a control device for the PCU 120 and a control device for the power storage device 110, may be provided.
  • the hybrid vehicle having the internal combustion engine and rotary electric machines as drive sources it is desirable for the hybrid vehicle having the internal combustion engine and rotary electric machines as drive sources to run in the EV running mode using only the driving force of the motor-generators while the engine is being stopped, on as many occasions as possible, in view of improvement of the fuel economy and reduction of emissions.
  • the vehicle may be required to run in the HV running mode in which the driving force of the engine is used as well.
  • the running mode of the vehicle is switched from the EV running mode to the HV running mode, and the engine is started while the temperature of the engine body is low, as in the case where the vehicle has been kept running in the EV running mode for a long period of time, the engine may be operated with relatively low combustion efficiency until it is warmed up, and may also be operated with poor emissions.
  • FIG. 2 is a functional block diagram useful for explaining the warm-up control executed by the ECU 300 in this embodiment. Respective functional blocks illustrated in the functional block diagram of FIG 2 are implemented by the ECU 300, through hardware or software processing.
  • the ECU 300 includes an SOC calculating unit 310, determining unit 320, engine controller 330, valve controller 340, motor controller 350, and a transmission controller 360.
  • the SOC calculating unit 310 receives the voltage VB, current IB, and temperature TB from the power storage device 110, and calculates the SOC based on these pieces of information.
  • the SOC calculating unit 310 outputs the calculated SOC to the determining unit 320.
  • the determining unit 320 receives the coolant temperature TW of the engine 130, the temperature TF of the lubricant of the drive-train 200, the temperatures TM1, TM2 of the respective motor-generators 210, 220, the accelerator pedal position signal ACC from the accelerator pedal 190, and the shift position signal POS from the shift lever 195, in addition to the SOC from the SOC calculating unit 310.
  • the determining unit 320 receives the rotational speeds NRMl, NRM2 of the motor-generators 210, 220, and the rotational speed NE of the engine 130. Furthermore, the determining unit 320 receives the vehicle speed VS from the speed sensor 180.
  • the determining unit 320 calculates the user-requested power based on the accelerator pedal position signal ACC. Also, the determining unit 320 calculates torque command values TRMl, TRM2, TRE of the motor-generators 210, 220 and the engine 130, using the rotational speeds NRMl, NRM2, NE of the motor-generators 210, 220 and the engine 130, and the current speed ratio of the automatic transmission 250. The determining unit 320 outputs the calculated torque command value TRE to the engine controller 330, and outputs the torque command values TRMl, TRM2 to the motor controller 350.
  • the engine controller 330 produces a control signal DRV including information, such as the fuel injection amount and the ignition timing, according to the torque command value TRE, and controls the engine 130 according to the control signal DRV.
  • the motor controller 350 produces control signals PWC, PWT1, PWI2 of the converter 121 and the inverters 122, 123, and controls the converter 121 and the inverters 122, 123, according to the control signals PWC, PWI1, PWI2.
  • the determining unit 320 sets the speed ratio of the automatic transmission 250, based on the shift position signal POS and the vehicle speed VS, and outputs a signal RNG indicative of the speed ratio to the transmission controller 360.
  • the transmission controller 360 produces a signal SFT and controls the automatic transmission 250, according to the signal RNG.
  • the determining unit 320 determines whether heat exchange needs to be effected in the heat-exchange device 160, based on the received temperatures TW, TF, TM1, TM2, and outputs a signal OPN for opening or closing the switching valve 170 to the valve controller 340.
  • the valve controller 340 produces a control signal ST and controls the switching valve 170, according to the signal OPN.
  • FIG. 3 is a flowchart useful for explaining details of a warm-up control routine executed by the ECU 300 in this embodiment.
  • Control routines illustrated in the flowcharts of FIG 3, and FIG. 6 and FIG. 7 are implemented by calling programs stored in advance in the ECU 300 from a main routine, and executing each of the programs at given intervals of time. It is also possible to implement operations in a part of steps in each flowchart, by constructing dedicated hardware (electronic circuit).
  • step (which will be abbreviated to "S") 100 determines in step (which will be abbreviated to "S") 100 whether the temperature TW of the coolant of the engine 130 is higher than a given reference temperature Tl based on which it is determined whether the engine 130 needs to be warmed up.
  • the ECU 300 proceeds to SI 70 to place the switching valve 170 in a closed position, so as to place the heat-exchange device 160 in a non-activated state.
  • the ECU 300 determines that the engine 130 needs to be warmed up by use of the heat-exchange device 160, and proceeds to SI 10.
  • the ECU 300 determines whether the temperature TM2 of the motor-generator 220 (MG2) is higher than a reference temperature T2.
  • the reference temperature T2 is a reference value based on which it is determined whether the motor-generator has been warmed up to a temperature level high enough to warm the coolant.
  • the ECU 300 proceeds to SI 20 to determine whether the lubricant temperature TF is higher than a reference temperature T3.
  • T3 is higher than Tl .
  • the ECU 300 determines in SI 30 whether the engine is about to be started. If the engine is about to be started (YES in SI 30), the switching valve 170 is opened so as to activate the heat-exchange device 160 in SI 40. Although not illustrated in FIG. 3, in SI 40, an electric pump (not shown) is driven to circulate the coolant of the engine 130 within the engine 130. As a result, the engine 130 is indirectly warmed via the coolant, using the heat from the lubricant.
  • the ECU 300 determines whether the lubricant temperature TF is higher than a temperature T4 that is further lower than the reference temperature T3.
  • the ECU 300 proceeds to S170 to place the heat-exchange device 160 in the non-activated state.
  • the ECU 300 proceeds to SI 60 to drive the motor-generator 210 (MGl) to generate electric power while no combustion operation is performed in the engine 130.
  • MGl motor-generator 210
  • a temperature rise of the lubricant is promoted due to heat generated by the motor-generator 210.
  • the crankshaft of the engine 130 is rotated, warm-up of the engine 130 is promoted due to frictional heat.
  • step SI 60 of this embodiment the motor-generator 210 is driven to generate electric power, so as to crank the engine 130, as described above.
  • the engaging device 240 may be engaged so as to keep the engine 130 in a stopped state, and the motor-generator 210 may be driven for power running, so that the driving force for running the vehicle is generated by both of the motor-generators 210, 220.
  • the temperature TW of the coolant and the temperature TM2 of the motor-generator 220 (MG2) are compared with the respective reference temperatures, as conditions for determining whether warm-up control is to be performed.
  • heat exchange may be basically effected provided that the lubricant temperature TF is higher than the coolant temperature TW.
  • FIG. 6 is a flowchart useful for explaining details of a warm-up control routine according to the first modified example of this embodiment.
  • SI 00 and SI 10 in the flowchart of FIG. 3 are replaced by SI 00 A.
  • steps that overlap those of FIG. 3 will not be repeatedly explained.
  • the ECU 300 determines in S100A whether a temperature difference obtained by subtracting the coolant temperature TW of the engine 130 from the lubricant temperature TF of the drive-train 200 is larger than a given threshold value a.
  • the ECU 300 proceeds to SI 70 to place the heat-exchange device 160 in a non-activated state.
  • the ECU 300 proceeds to S120, and S120 and subsequent steps are executed in the same manner as in the case of FIG. 3, so that the engine 130 is warmed up using the heat-exchange device 160 if certain conditions are satisfied.
  • the internal combustion engine can be warmed up before the engine is started, when the hybrid vehicle having the internal combustion engine and the rotary electric machines as drive sources switches from the EV running mode to the HV running mode.
  • the temperature of the engine coolant may be raised earlier than the lubricant of the drive-train, due to the combustion operation of the engine.
  • the lubricant of the drive-train may be warmed by heat of the engine coolant, so that the viscosity of the lubricant can be reduced to a moderate viscosity, and shock that would occur upon shifting of the automatic transmission can be alleviated.
  • the motor-generators can be warmed up and brought into a thermally stable condition at an early opportunity.
  • the vehicle has an arrangement of warming the lubricant using the engine coolant when the engine coolant temperature is higher than the lubricant temperature, in addition to the arrangement of warming the engine coolant using the lubricant as described above.
  • FIG. 7 is a flowchart useful for explaining details of a warm-up control routine according to the second modified example of this embodiment.
  • the ECU 300 determines in S200 whether the engine 130 is driven earlier than driving of the motor-generator(s).
  • the ECU 300 proceeds to S210 to determine whether the coolant temperature TW of the engine 130 is higher than a given threshold value Tl.
  • the ECU 300 determines that the engine 130 has not been sufficiently warmed up, and proceeds to S230 to place the heat-exchange device 160 in a non-activated state. Thus, the ECU 300 gives priority to warm-up of the engine 13.
  • the ECU 300 proceeds to S220 to open or release the switching valve 170 and activate the heat-exchange device 160, so as to warm the lubricant using heat of the engine coolant. In this manner, the motor-generators 210, 220, the automatic transmission 250, etc. in the drive-train 200 are warmed up.
  • the ECU 300 proceeds to S230 to place the heat-exchange device 160 in the non-activated state.
  • the motor-generator is driven earlier than driving of the engine in some situations, such as a situation where the vehicle switches from the EV running mode to the HV running mode as described above. In this situation, the operations as explained above with reference to FIG. 3 and FIG. 6 may be applied to step S230 of FIG 7.
  • the heat-exchange device may be de-activated when the temperature of the lubricant is raised to a given temperature.

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Abstract

A vehicle (100) includes an engine (130), a drive-train (200) including a rotary electric machine (210, 220) that operates as a drive source, a heat-exchange device (160) configured to effect heat exchange between a lubricant used in the drive-train (200) and a cooling medium used in the engine (130), and a control device (300) configured to activate the heat-exchange device (160) so as to warm up the engine (130) when the engine (130) is expected to be started while the vehicle (100) is running using driving force from the rotary electric machine (210, 220).

Description

HYBRID VEHICLE, WARM-UP CONTROL DEVICE FOR HYBRID VEHICLE, AND WARM-UP CONTROL METHOD FOR HYBRID VEHICLE
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The invention relates to a vehicle, a control device for the vehicle, and a control method for the vehicle, and more particularly relates to warm-up control of an internal combustion engine in a vehicle having a rotary electric machine and the internal combustion engine as drive sources.
2. Description of Related Art
[0002] A hybrid vehicle on which an internal combustion engine (such as an engine) and an electric motor are installed as vehicle power sources is known. The hybrid vehicle may preferentially run in an electrically powered running mode (which will also be called "EV (Electric Vehicle) running mode"), using only the output of the electric motor while stopping the operation of the engine, in order to improve the fuel economy.
[0003] Japanese Patent Application Publication No. 2009-120043 (JP 2009-120043 A) discloses a vehicle including an operating mechanism to which first and second rotary electric machines and an engine are coupled, and a clutch for fixing a rotary shaft of the engine. In this vehicle, the clutch is arranged to fix the rotary shaft of the engine when the vehicle runs in the EV running mode.
[0004] According to JP 2009- 120043 A, the engine rotary shaft is fixed by the clutch, so that driving force of both of the first and second rotary electric machines can be transmitted to drive wheels, and a loss that would be caused by rotation of the engine can be reduced. As a result, the power transmission efficiency can be improved. SUMMARY OF THE INVENTION
[0005] In the hybrid vehicle that preferentially runs in the EV running mode, when the vehicle switches from the EV running mode to a running mode using both the electric motor and the engine (which will be called "HV (Hybrid Vehicle) running mode"), the engine may be started in a condition where the engine is not sufficiently warmed up. In this condition, the combustion efficiency of the engine may be reduced, and emissions may deteriorate.
[0006] The invention provides a vehicle, which is a hybrid vehicle having an internal combustion engine and a rotary electric machine as drive sources, in which the internal combustion engine can be appropriately warmed up when the vehicle switches from the EV running mode to the HV running mode. The invention also provides a control device for the vehicle, and a control method for the vehicle.
[0007] A vehicle according to a first aspect of the invention includes an engine, a drive-train including a first rotary electric machine that operates as a drive source, a heat-exchange device configured to effect heat exchange between a lubricant used in the drive-train and a cooling medium used in the engine, and a control device. The control device is configured to activate the heat-exchange device so as to warm up the engine when the engine is expected to be started while the vehicle is running using driving force from the first rotary electric machine.
[0008] The vehicle may further include a power storage device configured to supply electric power for driving the first rotary electric machine. The control device may activate the heat-exchange device when a state of charge of the power storage device is lower than a given reference value. Also, when the state of charge of the power storage device is lower than the given reference value, the control device may determine that the engine is expected to be started, and activate the heat-exchange device.
[0009] When a temperature of the first rotary electric machine is lower than a given reference temperature, the control device may keep the heat-exchange device in a non-activated state even in the case where the engine is expected to be started.
[0010] When a temperature of the lubricant is lower than a given reference temperature, the control device may keep the heat-exchange device in a non-activated state even in the case where the engine is expected to be started.
[0011] The control device may activate the heat-exchange device when a temperature difference obtained by subtracting a temperature of the cooling medium from a temperature of the lubricant is larger than a predetermined threshold value.
[0012] The drive-train may further include a second rotary electric machine, and a differential device including a first rotary element, a second rotary element, and a third rotary element. In this case, the first rotary electric machine is coupled to the first rotary element, and the second rotary electric machine is coupled to the second rotary element, while the engine is coupled to the third rotary element. The control device may drive both the first rotary electric machine and the second rotary electric machine so as to warm the lubricant when a temperature of the lubricant is lower than a given reference temperature.
[0013] In the arrangement as described above, the drive-train may further include . an engaging element that suppresses rotation of the third rotary element, and a transmission provided between the second rotary element and the drive wheels.
[0014] When a temperature of the cooling medium is higher than a given reference temperature, and is higher than a temperature of the lubricant, the control device may activate the heat-exchange device so as to warm the lubricant by use of the cooling medium.
[0015] The vehicle may further include a switching portion provided in a flow channel of the lubricant that flows into the heat-exchange device and configured to switch between a first position in which the lubricant is allowed to flow into the heat-exchange device and a second position in which the lubricant is inhibited from flowing into the heat-exchange device. The control device may activate the heat-exchange device, by controlling the switching portion so as to cause the lubricant to flow into the heat-exchange device.
[0016] A second aspect of the invention provides a control device for a vehicle including an engine, a drive-train including a rotary electric machine that operates as a drive source, and a heat-exchange device configured to effect heat exchange between a lubricant used in the drive-train and a cooling medium used in the engine. The control device includes a determining unit configured to determine whether the engine is expected to be started while the vehicle is running using driving force from the rotary electric machine, and a controller configured to activate the heat-exchange device so as to warm up the engine in response to a determination that the engine is expected to be started.
[0017] A third aspect of the invention provides a control method for a vehicle including an engine, a drive-train including a rotary electric machine that operates as a drive source, and a heat-exchange device configured to effect heat exchange between a lubricant used in the drive-train and a cooling medium used in the engine. The control method includes the steps of: determining whether the engine is expected to be started while the vehicle is running using driving force from the rotary electric machine, and activating the heat-exchange device so as to warm up the engine in response to a determination that the engine is expected to be started.
[0018] According to the above aspects of the invention, in the hybrid vehicle having the internal combustion engine and the rotary electric machine as drive sources, the internal combustion engine can be warmed up before it is started, when the vehicle switches from the EV running mode to the HV running mode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:
FIG. 1 is an overall block diagram of a vehicle according to one embodiment of the invention;
FIG. 2 is a functional block diagram useful for explaining warm-up control executed by ECU in the embodiment of FIG. 1;
FIG. 3 is a flowchart useful for explaining details of a warm-up control routine executed by the ECU in the embodiment of FIG. 1;
FIG. 4 is a view showing a first example of map that defines reference temperatures used for determining whether a heat-exchange device can be activated;
FIG. 5 is a view showing a- second example of map that defines reference temperatures used for determining whether a heat-exchange device can be activated;
FIG. 6 is a flowchart useful for explaining details of a warm-up control routine according to a first modified example of the embodiment of FIG. 1 ; and
FIG 7 is a flowchart useful for explaining details of a warm-up control routine according to a second modified example of the embodiment of FIG. 1.
DETAILED DESCRIPTION OF EMBODIMENTS
[0020] In the following, one embodiment of the invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals are assigned to the same or corresponding components or portions, of which explanation will not be repeated.
[0021] FIG. 1 is an overall block diagram of a vehicle 100 according to one embodiment of the invention. Referring to FIG 1, the vehicle 100 includes a power storage device 110, a PCU (Power Control Unit) as a drive unit, an engine 130 as an internal combustion engine, a drive-train 200, a speed reducer 140, drive wheels 150, a heat-exchange device 160, and an ECU (Electronic Control Unit) 300 as a control device.
[0022] The PCU 120 includes a converter 121 and inverters 122, 123. The drive-train 200 includes motor-generators 210 (MG1), 220 (MG2), a differential device 230, an engaging device 240, and an automatic transmission (A/T) 250 (which will also be simply called "transmission").
[0023] The power storage device 110 is an electric power storage element configured to be able to be charged with electric power and discharge electric power. The power storage device 110 includes a power storage element, which may be a secondary battery, such as a lithium-ion battery, nickel-metal-hydride battery, or a lead storage battery, or an electric double layer capacitor. [0024] The power storage device 110 is electrically coupled to the converter 121 in the PCU 120. The power storage device 110 supplies electric power for generating driving force of the vehicle 100, to the PCU 120. Also, the power storage device 110 stores electric power generated by the motor-generators 210, 220. The output of the power storage device 110 is about 200V, for example.
[0025] The power storage device 110 is provided with a voltage sensor, a current sensor, and a temperature sensor, all of which are not shown in the drawings. The ECU 300 receives a value of voltage VB of the power storage device 110 detected by the voltage sensor, a value of current IB that flows into and out of the power storage device 110, which is detected by the current sensor, and a temperature TB of the power storage device 110 detected by the temperature sensor.
[0026] The converter 121 boosts the voltage of the power storage device 110, based on a control signal PWC from the ECU 300, and supplies the voltage to the inverters 122, 123. Also, the converter 121 steps down the voltage generated by the motor-generators 210, 220 and rectified by the inverters 122, 123, and charges the power storage device 110 with the resulting power.
[0027] The inverters 122, 123 are connected in parallel with each other, as seen from the converter 121. The inverters 122, 123 convert DC (direct-current) power supplied from the converter 121, into AC (alternating-current) power, and drive the motor-generators 210, 220, respectively, based on control signals PWl l, PW12 received from the ECU 300.
[0028] Each of the motor-generators 210, 220 is an AC rotary electric machine, such as a permanent-magnet-type synchronous motor including a rotor in which a permanent magnet is embedded.
[0029] The motor-generators 210, 220 and the engine 130 are coupled to each other by a differential device 230. The differential device 230 includes a planetary gear mechanism. The motor-generator 210 is coupled to a sun gear S of the planetary gear mechanism, and the engine 130 is coupled to a planetary carrier C of the planetary gear mechanism, while the motor-generator 220 is coupled to a ring gear R of the planetary gear mechanism.
[0030] The engine 130 is controlled according to a control signal DRV received from the ECU 300. The motor-generators 210, 220 and the engine 130 are operated by the ECU 300 in a coordinated manner, so as to generate required vehicle driving force. The vehicle 100 is able to run in a so-called EV running mode, using only the driving force from the motor-generators 210, 220, while the engine 130 is being stopped.
[0031] Thus, the differential device 230, which is arranged to be coupled with the engine 130 and the motor-generators 210, 220, also functions as a continuously variable transmission.
[0032] An output shaft of the motor-generator 220 is coupled to an input shaft of the automatic transmission 250. An output shaft of the automatic transmission 250 is coupled to the drive wheels 150 via a speed reducer 140. The automatic transmission 250 is controlled according to a control signal SFT received from the ECU 300, so as to change the speed ratio between the motor-generator 220 and the drive wheels 150. In this connection, the automatic transmission 250 may be a stepwise variable transmission for which a plurality of different fixed speed ratios are set in advance, or a continuously variable transmission capable of continuously change the speed ratio.
[0033] The engaging device 240 typically takes the form of a clutch or a brake. The engaging device 240 is controlled according to a control signal SIG received from the ECU 300, so as to fix an output shaft of the engine 130 when it is placed in an engaged state. While the vehicle is running in the EV running mode, the engaging device 240 fixes the output shaft of the engine 130, so that the driving force of both of the motor-generators 210, 220 can be transmitted to the drive wheels 150. At this time, rotation of the engine 130 is suppressed, . so that a mechanical transmission loss that would be caused by rotation of the rotary shaft of the engine 130 can be reduced.
[0034] A speed sensor 180 for detecting the rotational speed of the drive wheels 150, or the vehicle speed, is provided in the vicinity of the drive wheel 150. The speed sensor 180 outputs a speed value VS thus detected, to the ECU 300. While the speed sensor 180 is located in the vicinity of the drive wheel 150 in this embodiment of FIG 1, the location of the speed sensor 180 is not limited to this, but the speed sensor 180 may be located in the vicinity of a driven wheel (not shown), or may be located in the vicinity of the output shaft of the drive-train 200. If the vehicle speed can be obtained by calculation, from the rotational speed of the motor-generator 220 and the speed ratio of the automatic transmission 250, for example, the speed sensor may be omitted.
[0035] The heat-exchange device 160 (which will also be called "warmer") includes a pipe 161 as a part of a channel through which a lubricant (ATF) for lubricating the interior of the drive-train 200 flows, and a pipe 162 as a part of a channel through which a cooling medium (e.g., a coolant) for cooling the engine 130 flows. The pipes 161, 162 are located close to each other or in contact with each other, and heat exchange takes place between the lubricant and the coolant when there is a temperature difference between the lubricant flowing through the pipe 161 and the coolant flowing through the pipe 162.
[0036] A switching valve 170 as a switching portion is provided in a portion of the pipe 161 through which the lubricant flows from the drive-train 200 into the heat-exchange device 160. The switching valve 170 is controlled according to a control signal ST received from the ECU 300, so as to be placed in a selected one of a communicating position in which the lubricant is allowed to flow from the drive-train 200 into the heat-exchange device 160, and a non-communicating position in which the lubricant is inhibited from flowing from the drive-train 200 into the heat-exchange device 160.
[0037] In the drive-train 200, a temperature sensor 260 for detecting the temperature of the lubricant is provided at around a location where the lubricant flows into the pipe 161. The temperature sensor 260 outputs the detected temperature TF of the lubricant to the ECU 300. While the temperature sensor 260 is provided inside the drive-train 200 in the embodiment of FIG. 1, the temperature sensor 260 may be provided outside the drive-train 200, more specifically, in a channel that extends from the drive-train 200 to the switching valve 170.
[0038] Similarly, in the engine 130, a temperature sensor 135 for detecting the temperature of the coolant is provided at around a location where the coolant flows into the pipe 162. The temperature sensor 135 outputs the detected temperature TW of the coolant to the ECU 300. The temperature sensor 135 may also be provided outside the erigine 130, more specifically, in a channel that extends from the engine 130 to the heat-exchange device 160.
[0039] The ECU 300 includes a CPU (Central Processing Unit), a storage device and input and output buffers, all of which are not shown in FIG. 1, and is configured to receive signals from respective sensors, etc. and transmit control signals to respective devices, so as to control the vehicle 100 and respective devices. The control of the vehicle 100 and its devices is not limited to processing by software, but may be implemented by dedicated hardware (electronic circuits).
[0040] The ECU 300 receives detected values of the voltage VB, current IB and temperature IB from the power storage device 110. The ECU 300 calculates the state of charge (which will also be called "SOC") of the power storage device 110, based on these pieces of information.
[0041] The ECU 300 receives the rotational speed NE of the engine 130 from the engine 130. The ECU 300 also receives the rotational speeds NM1, NM2 and temperatures TM1, TM2 of the respective motor-generators 210, 220.
[0042] The ECU 300 receives a signal ACC indicative of an accelerator pedal position from the accelerator pedal 190, and calculates required power based on the signal ACC. The ECU 300 also calculates torque to be produced by the engine 130 and the motor-generators 210, 220.
[0043] Also, the ECU 300 receives a signal POS indicative of a shift position from a shift lever 195, and controls the engine 130, motor-generators 210, 220, and the automatic transmission 250, based on the signal POS.
[0044] While one control device is provided as the ECU 300 in the embodiment of FIG 1 , individual control devices for respective functions or respective devices to be controlled, such as a control device for the PCU 120 and a control device for the power storage device 110, may be provided.
[0045] It is desirable for the hybrid vehicle having the internal combustion engine and rotary electric machines as drive sources to run in the EV running mode using only the driving force of the motor-generators while the engine is being stopped, on as many occasions as possible, in view of improvement of the fuel economy and reduction of emissions. However, when the SOC of the power storage device is reduced, or when high power or output is required, such as when the vehicle runs on an uphill or is accelerated, the vehicle may be required to run in the HV running mode in which the driving force of the engine is used as well.
[0046] When the running mode of the vehicle is switched from the EV running mode to the HV running mode, and the engine is started while the temperature of the engine body is low, as in the case where the vehicle has been kept running in the EV running mode for a long period of time, the engine may be operated with relatively low combustion efficiency until it is warmed up, and may also be operated with poor emissions.
[0047] Thus, in this embodiment, when the running mode is switched from the EV running mode to the HV running mode, warm-up control for warming up the engine early is executed by warming the engine coolant by use of heat of the lubricant of the drive-train including the motor-generators. With this control, reduction of the combustion efficiency and deterioration of the emissions are suppressed.
[0048] FIG. 2 is a functional block diagram useful for explaining the warm-up control executed by the ECU 300 in this embodiment. Respective functional blocks illustrated in the functional block diagram of FIG 2 are implemented by the ECU 300, through hardware or software processing.
[0049] Referring to FIG 1 and FIG 2, the ECU 300 includes an SOC calculating unit 310, determining unit 320, engine controller 330, valve controller 340, motor controller 350, and a transmission controller 360.
[0050] The SOC calculating unit 310 receives the voltage VB, current IB, and temperature TB from the power storage device 110, and calculates the SOC based on these pieces of information. The SOC calculating unit 310 outputs the calculated SOC to the determining unit 320. [0051] The determining unit 320 receives the coolant temperature TW of the engine 130, the temperature TF of the lubricant of the drive-train 200, the temperatures TM1, TM2 of the respective motor-generators 210, 220, the accelerator pedal position signal ACC from the accelerator pedal 190, and the shift position signal POS from the shift lever 195, in addition to the SOC from the SOC calculating unit 310. Also, the determining unit 320 receives the rotational speeds NRMl, NRM2 of the motor-generators 210, 220, and the rotational speed NE of the engine 130. Furthermore, the determining unit 320 receives the vehicle speed VS from the speed sensor 180.
[0052] The determining unit 320 calculates the user-requested power based on the accelerator pedal position signal ACC. Also, the determining unit 320 calculates torque command values TRMl, TRM2, TRE of the motor-generators 210, 220 and the engine 130, using the rotational speeds NRMl, NRM2, NE of the motor-generators 210, 220 and the engine 130, and the current speed ratio of the automatic transmission 250. The determining unit 320 outputs the calculated torque command value TRE to the engine controller 330, and outputs the torque command values TRMl, TRM2 to the motor controller 350.
[0053] The engine controller 330 produces a control signal DRV including information, such as the fuel injection amount and the ignition timing, according to the torque command value TRE, and controls the engine 130 according to the control signal DRV. The motor controller 350 produces control signals PWC, PWT1, PWI2 of the converter 121 and the inverters 122, 123, and controls the converter 121 and the inverters 122, 123, according to the control signals PWC, PWI1, PWI2.
[0054] The determining unit 320 sets the speed ratio of the automatic transmission 250, based on the shift position signal POS and the vehicle speed VS, and outputs a signal RNG indicative of the speed ratio to the transmission controller 360. The transmission controller 360 produces a signal SFT and controls the automatic transmission 250, according to the signal RNG.
[0055] The determining unit 320 determines whether heat exchange needs to be effected in the heat-exchange device 160, based on the received temperatures TW, TF, TM1, TM2, and outputs a signal OPN for opening or closing the switching valve 170 to the valve controller 340. The valve controller 340 produces a control signal ST and controls the switching valve 170, according to the signal OPN.
[0056] FIG. 3 is a flowchart useful for explaining details of a warm-up control routine executed by the ECU 300 in this embodiment. Control routines illustrated in the flowcharts of FIG 3, and FIG. 6 and FIG. 7 (which will be described later) are implemented by calling programs stored in advance in the ECU 300 from a main routine, and executing each of the programs at given intervals of time. It is also possible to implement operations in a part of steps in each flowchart, by constructing dedicated hardware (electronic circuit).
[0057] Referring to FIG. 1 and FIG 3, when the vehicle 100 runs in the EV running mode using only the driving force of the motor-generator 220, while the engine 130 is being stopped, the ECU 300 determines in step (which will be abbreviated to "S") 100 whether the temperature TW of the coolant of the engine 130 is higher than a given reference temperature Tl based on which it is determined whether the engine 130 needs to be warmed up.
[0058] If the coolant temperature TW is higher than the reference temperature Tl (TW>T1) (YES in SI 00), the engine 130 has already been sufficiently warmed up, and does not need to be warmed up by use of the heat-exchange device 160. Therefore, the ECU 300 proceeds to SI 70 to place the switching valve 170 in a closed position, so as to place the heat-exchange device 160 in a non-activated state.
[0059] If the coolant temperature TW is equal to or lower than the reference temperature Tl (TW<T1) (NO in SI 00), the ECU 300 determines that the engine 130 needs to be warmed up by use of the heat-exchange device 160, and proceeds to SI 10. In SI 10, the ECU 300 determines whether the temperature TM2 of the motor-generator 220 (MG2) is higher than a reference temperature T2. The reference temperature T2 is a reference value based on which it is determined whether the motor-generator has been warmed up to a temperature level high enough to warm the coolant.
[0060] If the motor temperature TM2 is equal to or lower than the reference temperature T2 (TM2<T2) (NO in SI 10), the motor-generator has not be sufficiently warmed up; therefore, the ECU 300 proceeds to SI 70 to place the heat-exchange device 160 in the non-activated state.
[0061] If the motor temperature TM2 is higher than the reference temperature T2 (TM2>T2) (YES in SI 10), on the other hand, the ECU 300 proceeds to SI 20 to determine whether the lubricant temperature TF is higher than a reference temperature T3. Here, T3 is higher than Tl .
[0062] If the lubricant temperature TF is higher than the reference temperature T3 (TF>T3) (YES in SI 20), the ECU 300 determines in SI 30 whether the engine is about to be started. If the engine is about to be started (YES in SI 30), the switching valve 170 is opened so as to activate the heat-exchange device 160 in SI 40. Although not illustrated in FIG. 3, in SI 40, an electric pump (not shown) is driven to circulate the coolant of the engine 130 within the engine 130. As a result, the engine 130 is indirectly warmed via the coolant, using the heat from the lubricant.
[0063] When the engine 130 has been started (NO in SI 30), the engine 130 is warmed up through a combustion operation thereof; therefore, the ECU 300 proceeds to SI 70 to place the heat-exchange device 160 in the non-activated state.
[0064] If it is determined in SI 20 that the lubricant temperature TF is equal to or lower than the reference temperature T3 (TF<T3) (NO in SI 20), the ECU 300 determines whether the lubricant temperature TF is higher than a temperature T4 that is further lower than the reference temperature T3.
[0065] If the lubricant temperature TF is higher than the reference temperature T4 (T3>TF>T4) (YES in SI 50), the ECU 300 proceeds to S170 to place the heat-exchange device 160 in the non-activated state.
[0066] If the lubricant temperature TF is equal to or lower than the reference temperature T4 (TF<T4) (NO in SI 50), the ECU 300 proceeds to SI 60 to drive the motor-generator 210 (MGl) to generate electric power while no combustion operation is performed in the engine 130. As a result, a temperature rise of the lubricant is promoted due to heat generated by the motor-generator 210. Further, since the crankshaft of the engine 130 is rotated, warm-up of the engine 130 is promoted due to frictional heat.
[0067] In step SI 60 of this embodiment, the motor-generator 210 is driven to generate electric power, so as to crank the engine 130, as described above. However, the engaging device 240 may be engaged so as to keep the engine 130 in a stopped state, and the motor-generator 210 may be driven for power running, so that the driving force for running the vehicle is generated by both of the motor-generators 210, 220.
[0068] Also, it may be determined whether the heat-exchange device needs to be activated or not, using a map as shown in FIG. 4 or FIG. 5, for example.
[0069] With the control performed according to the routine as described above, when the hybrid vehicle having the internal combustion engine and the rotary electric machines as drive sources switches from the EV running mode to the HV running mode, the internal combustion engine can be warmed up before the engine is started. As a result, a combustion operation is less likely or unlikely to be performed in the engine in a condition where the engine temperature is low; therefore, reduction of the combustion efficiency and deterioration of emissions can be suppressed.
[0070] In the flowchart of FIG. 3 as described above, the temperature TW of the coolant and the temperature TM2 of the motor-generator 220 (MG2) are compared with the respective reference temperatures, as conditions for determining whether warm-up control is to be performed. However, in order to warm the coolant by use of the lubricant, heat exchange may be basically effected provided that the lubricant temperature TF is higher than the coolant temperature TW.
[0071] Therefore, in a first modified example, it is determined whether warm-up control using the heat-exchange device 160 is to be performed, using a temperature difference between the lubricant temperature TF and the coolant temperature TW.
[0072] FIG. 6 is a flowchart useful for explaining details of a warm-up control routine according to the first modified example of this embodiment. In FIG 6, SI 00 and SI 10 in the flowchart of FIG. 3 are replaced by SI 00 A. In FIG 6, steps that overlap those of FIG. 3 will not be repeatedly explained.
[0073] Referring to FIG. 6, when the vehicle is mnning in the EV running mode using only the driving force of the motor-generator 220, while the engine 130 is kept in a stopped state, the ECU 300 determines in S100A whether a temperature difference obtained by subtracting the coolant temperature TW of the engine 130 from the lubricant temperature TF of the drive-train 200 is larger than a given threshold value a.
[0074] If the temperature difference between the lubricant temperature TF and the coolant temperature TW is equal to or smaller than the threshold value a (TF-TW<a) (NO in S100A), the coolant cannot be sufficiently warmed by use of the lubricant: therefore, the ECU 300 proceeds to SI 70 to place the heat-exchange device 160 in a non-activated state.
[0075] On the other hand, if the temperature difference between the lubricant temperature TF and the coolant temperature TW is larger than the threshold value a (TF-TW>a) (YES in S100A), the ECU 300 proceeds to S120, and S120 and subsequent steps are executed in the same manner as in the case of FIG. 3, so that the engine 130 is warmed up using the heat-exchange device 160 if certain conditions are satisfied.
[0076] In the case where the control is performed according to the above-described routine of FIG. 6, too, the internal combustion engine can be warmed up before the engine is started, when the hybrid vehicle having the internal combustion engine and the rotary electric machines as drive sources switches from the EV running mode to the HV running mode.
[0077] In the above-described embodiment, when the vehicle switches from the EV running mode to the HV running mode, the engine coolant is warmed by heat transferred from the lubricant of the drive-train including the motor-generators, so that the engine is warmed up before it is started.
[0078] Meanwhile, when the engine is driven earlier than driving of the motor-generator(s), such as when the vehicle is initially started, the temperature of the engine coolant may be raised earlier than the lubricant of the drive-train, due to the combustion operation of the engine. In this case, the lubricant of the drive-train may be warmed by heat of the engine coolant, so that the viscosity of the lubricant can be reduced to a moderate viscosity, and shock that would occur upon shifting of the automatic transmission can be alleviated. At the same time, the motor-generators can be warmed up and brought into a thermally stable condition at an early opportunity.
[0079] Thus, in a second modified example, the vehicle has an arrangement of warming the lubricant using the engine coolant when the engine coolant temperature is higher than the lubricant temperature, in addition to the arrangement of warming the engine coolant using the lubricant as described above.
[0080] FIG. 7 is a flowchart useful for explaining details of a warm-up control routine according to the second modified example of this embodiment.
[0081] Referring to FIG. 1 and FIG. 7, the ECU 300 determines in S200 whether the engine 130 is driven earlier than driving of the motor-generator(s).
[0082] If the engine 130 is driven earlier than driving of the motor-generator(s)
(YES in S200), the ECU 300 proceeds to S210 to determine whether the coolant temperature TW of the engine 130 is higher than a given threshold value Tl.
[0083] If the coolant temperature TW is equal to or lower than the given threshold value Tl (TW<T1) (NO in S210), the ECU 300 determines that the engine 130 has not been sufficiently warmed up, and proceeds to S230 to place the heat-exchange device 160 in a non-activated state. Thus, the ECU 300 gives priority to warm-up of the engine 13.
[0084] If the coolant temperature TW is higher than the given threshold value Tl (TW>T1) (YES in S210), the ECU 300 proceeds to S220 to open or release the switching valve 170 and activate the heat-exchange device 160, so as to warm the lubricant using heat of the engine coolant. In this manner, the motor-generators 210, 220, the automatic transmission 250, etc. in the drive-train 200 are warmed up.
[0085] On the other hand, if the engine 130 is not driven earlier than driving of the motor-generator(s) (NO in S200), the ECU 300 proceeds to S230 to place the heat-exchange device 160 in the non-activated state.
[0086] The motor-generator is driven earlier than driving of the engine in some situations, such as a situation where the vehicle switches from the EV running mode to the HV running mode as described above. In this situation, the operations as explained above with reference to FIG. 3 and FIG. 6 may be applied to step S230 of FIG 7.
[0087] Although not illustrated in FIG 7, the heat-exchange device may be de-activated when the temperature of the lubricant is raised to a given temperature.
[0088] With the control performed according to the routine as described above, when the engine is driven earlier than driving of the motor-generator(s), and the temperature of the engine coolant is higher than that of the lubricant, the lubricant is warmed by the engine coolant, so that the drive-train can be warmed up early.
[0089] It is to be understood that the illustrated embodiment and its modified examples disclosed herein are merely exemplary in all respects, and not restrictive. The scope of the invention is not defined by the above description of the embodiment and its modified examples, but is defined by the appended claims, and is intended to include all changes within the range of the claims and equivalents thereof.

Claims

CLAIMS:
1. A vehicle comprising:
an engine;
a drive-train including a first rotary electric machine that operates as a drive source; a heat-exchange device configured to effect heat exchange between a lubricant used in the drive-train and a cooling medium used in the engine; and
a control device configured to activate the heat-exchange device so as to warm up the engine when the engine is expected to be started while the vehicle is running using driving force from the first rotary electric machine.
2. The vehicle according to claim 1 , further comprising:
a power storage device configured to supply electric power for driving the first rotary electric machine, wherein
the control device activates the heat-exchange device when a state of charge of the power storage device is lower than a given reference value.
3. The vehicle according to claim 2, wherein
when the state of charge of the power storage device is lower than the given reference value, the control device determines that the engine is expected to be started, and activates the heat-exchange device.
4. The vehicle according to claim 1, wherein
when a temperature of the first rotary electric machine is lower than a given reference temperature, the control device keeps the heat-exchange device in a non-activated state even in the case where the engine is expected to be started.
5. The vehicle according to claim 1, wherein
when a temperature of the lubricant is lower than a given reference temperature, the control device keeps the heat-exchange device in a non-activated state even in the case where the engine is expected to be started.
6. The vehicle according to claim 1, wherein
the control device activates the heat-exchange device when a temperature difference obtained by subtracting a temperature of the cooling medium from a temperature of the lubricant is larger than a predetermined threshold value.
7. The vehicle according to claim 1 , wherein:
the drive-train further includes a second rotary electric machine, and a differential device including a first rotary element, a second rotary element, and a third rotary element; the first rotary electric machine is coupled to the first rotary element, and the second rotary electric machine is coupled to the second rotary element, while the engine is coupled to the third rotary element; and
the control device drives both the first rotary electric machine and the second rotary electric machine so as to warm the lubricant when a temperature of the lubricant is lower than a given reference temperature.
8. The vehicle according to claim 7, wherein
the drive-train further includes an engaging element that suppresses rotation of the third rotary element, and a transmission provided between the second rotary element and the drive wheels.
9. The vehicle according to claim 1, wherein
when a temperature of the cooling medium is higher than a given reference temperature, and is higher than a temperature of the lubricant, the control device activates the heat-exchange device so as to warm the lubricant by use of the cooling medium.
10. The vehicle according to claim 1 , further comprising: a switching portion provided in a flow channel of the lubricant that flows into the heat-exchange device and configured to switch between a first position in which the lubricant is allowed to flow into the heat-exchange device and a second position in which the lubricant is inhibited from flowing into the heat-exchange device, wherein
the control device activates the heat-exchange device, by controlling the switching portion so as to cause the lubricant to flow into the heat-exchange device.
11. A control device for a vehicle including an engine, a drive-train including a rotary electric machine that operates as a drive source, and a heat-exchange device configured to effect heat exchange between a lubricant used in the drive-train and a cooling medium used in the engine, the control device comprising:
a determining unit configured to determine whether the engine is expected to be started while the vehicle is running using driving force from the rotary electric machine ; and
a controller configured to activate the heat-exchange device so as to warm up the engine in response to a determination that the engine is expected to be started.
12. A control method for a vehicle including an engine, a drive-train including a rotary electric machine that operates as a drive source, and a heat-exchange device configured to effect heat exchange between a lubricant used in the drive-train and a cooling medium used in the engine, the control method comprising:
determining whether the engine is expected to be started while the vehicle is running using driving force from the rotary electric machine ; and
activating the heat-exchange device so as to warm up the engine in response to a determination that the engine is expected to be started.
PCT/IB2013/002966 2012-12-26 2013-12-18 Hybrid vehicle, warm-up control device for hybrid vehicle, and warm-up control method for hybrid vehicle WO2014102600A1 (en)

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