Hybrid vehicle

Abstract

To suppress a relative increase in input power of a power storage device when an engine is started during traveling.SOLUTION: A hybrid vehicle includes: an engine; a first motor; a planetary gear connected to the first motor, the engine, and a drive shaft connected to drive wheels; a second motor connected to the drive shaft; a power storage device connected to the first motor and the second motor via a power line; and a control device for controlling the engine, the first motor, and the second motor so that the vehicle travels with intermittent operation of the engine. When a start condition is satisfied during traveling, and the engine is started with cranking of the engine by the first motor, and when a temperature of the first motor is lower than a predetermined temperature, the control device controls the first motor while setting a smaller value than when the temperature of the first motor is equal to or higher than the predetermined temperature in a torque command of the first motor.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to hybrid vehicles. [Background technology]

[0002] A hybrid vehicle has been proposed in the past (see, for example, Patent Document 1). In this hybrid vehicle, when starting the engine by cranking the engine using the first motor, the first motor is controlled to output a relatively large first torque until the engine speed reaches a torque reduction start speed. Once the engine speed reaches the torque reduction start speed, the first motor is controlled to output a second torque smaller than the first torque. In this case, the torque reduction start speed is set based on whether the crank angle at the start of engine startup is within a predetermined crank angle range. This suppresses vibrations during engine startup. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-106598 Summary of the Invention [Problem to be solved by the invention]

[0004] In a hybrid vehicle having the above-described hardware configuration, when a start condition is met while the vehicle is running and the engine is started by cranking the engine using the first motor, the first motor is regeneratively driven in the initial stage of engine cranking and then powered thereafter. In light of this, it is necessary to start the engine while protecting the power storage device. It is generally known that when the temperature of the first motor is low, the magnet torque is larger for the same torque command, and thus the actual torque is larger, compared to when the temperature of the first motor is high. Due to this characteristic, if the first motor is controlled by setting the same torque command value for the first motor regardless of the temperature of the first motor, the generated power due to regenerative driving of the first motor in the initial stage of engine cranking when the temperature of the first motor is low may be relatively large, resulting in a relatively large input power to the power storage device.

[0005] The hybrid vehicle of the present disclosure has a primary object to prevent the input power of the power storage device from becoming relatively large when the engine is started while the vehicle is running. [Means for solving the problem]

[0006] The hybrid vehicle of the present disclosure employs the following measures to achieve the above-mentioned main object.

[0007] The hybrid vehicle of the present disclosure is The engine and a first motor; a planetary gear connected to the first motor, the engine, and a drive shaft connected to a drive wheel; and a second motor connected to the drive shaft. an electric storage device connected to the first motor and the second motor via a power line; a control device that controls the engine, the first motor, and the second motor so that the vehicle travels with intermittent operation of the engine; A hybrid vehicle comprising: When a start condition is satisfied during running and the engine is started with cranking of the engine by the first motor, when the temperature of the first motor is below a predetermined temperature, the control device controls the first motor by setting a smaller value as a torque command for the first motor compared to when the temperature of the first motor is equal to or higher than the predetermined temperature. The gist of this is as follows.

[0008] In the hybrid vehicle disclosed herein, when a start condition is met during driving and the engine is started by cranking the engine using the first motor, if the temperature of the first motor is below a predetermined temperature, the torque command for the first motor is set to a value that is smaller than when the temperature of the first motor is equal to or higher than the predetermined temperature, and the first motor is controlled accordingly. This prevents the actual torque of the first motor from increasing when the temperature of the first motor is below the predetermined temperature compared to when the temperature of the first motor is equal to or higher than the predetermined temperature. Therefore, when the temperature of the first motor is below the predetermined temperature, the generated power due to regenerative driving of the first motor is prevented from increasing relatively at the beginning of engine cranking, and the input power of the power storage device is prevented from increasing relatively. Here, the temperature of the first motor may be the temperature of the permanent magnets of the first motor, the temperature of the coils of the first motor, or the temperature of the lubricating oil that lubricates the first motor.

[0009] In the hybrid vehicle disclosed herein, the control device may set a start determination vehicle speed so that the input power of the power storage device when starting the engine while traveling is within a range of allowable input power, and the start condition may include a condition that the vehicle speed is equal to or greater than the start determination vehicle speed. In this case, as described above, when the temperature of the first motor is below a predetermined temperature, the input power of the power storage device at the beginning of engine cranking is prevented from becoming relatively large, thereby preventing the start determination vehicle speed from being set relatively low and preventing the allowable vehicle speed range for electric traveling accompanied by stopping the engine from becoming narrow.

[0010] In the hybrid vehicle of the present disclosure, when starting the engine while driving, if the temperature of the first motor is below the predetermined temperature, the control device may set the torque command to a smaller value as the temperature of the first motor decreases.

[0011] In the hybrid vehicle of the present disclosure, when starting the engine while traveling, the control device sets the torque command to increase to and maintain a first torque and then decrease when a decrease start condition is met, and the decrease start condition includes a crank angle condition that the crank angle of the engine is within a predetermined crank angle range when the vehicle speed is less than a predetermined vehicle speed, and may not include the crank angle condition when the vehicle speed is equal to or greater than the predetermined vehicle speed. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram of a hybrid vehicle 20 according to an embodiment of the present disclosure. [Figure 2] FIG. 4 is an explanatory diagram showing an example of a method for setting a cranking torque Tcr. [Figure 3] 3 is an explanatory diagram showing an example of the relationship between the rotation speeds of the rotating elements of the planetary gear 30 when starting the engine 22. FIG. [Figure 4] 10 is a flowchart showing an example of a processing routine executed by the HVECU 70. [Figure 5] FIG. 4 is an explanatory diagram showing an example of a map at low temperature. DETAILED DESCRIPTION OF THE INVENTION

[0013] A mode (embodiment) for carrying out the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic configuration diagram of a hybrid vehicle 20 according to an embodiment of the present disclosure. As shown in Fig. 1, the hybrid vehicle 20 according to the embodiment includes an engine 22, a planetary gear 30, motors MG1 and MG2, inverters 41 and 42, a battery 50, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 70.

[0014] The engine 22 is configured as an internal combustion engine that outputs power using fuel such as gasoline or diesel. A crankshaft 23 of the engine 22 is connected to a carrier 34 of the planetary gear 30. The operation of the engine 22 is controlled by an engine electronic control unit (hereinafter referred to as "engine ECU") 24.

[0015] The engine ECU 24 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. The engine ECU 24 receives signals from various sensors via its input ports. For example, the engine ECU 24 receives a crank angle θcr from a crank position sensor 23a that detects the rotational position of the crankshaft 23. The engine ECU 24 outputs various control signals via its output ports. For example, the engine ECU 24 outputs control signals to intake valves, fuel injection valves, and spark plugs (none of which are shown). The engine ECU 24 calculates the rotation speed Ne of the engine 22 based on the crank angle θcr of the crankshaft 23. The engine ECU 24 communicates with the HVECU 70.

[0016] The planetary gear 30 is configured as a single-pinion planetary gear mechanism and includes a sun gear 31 that is an external gear, a ring gear 32 that is an internal gear, a plurality of pinion gears 33 that mesh with the sun gear 31 and the ring gear 32, respectively, and a carrier 34 that supports the plurality of pinion gears 33 so that they can rotate and revolve freely. The sun gear 31 is connected to the rotor of the motor MG1. The ring gear 32 is connected to a drive shaft 37 that is connected to drive wheels 39a, 39b via a differential gear 38. As described above, the carrier 34 is connected to the crankshaft 23 of the engine 22.

[0017] Each of the motors MG1 and MG2 is configured as, for example, a synchronous generator motor, and includes a rotor with a permanent magnet embedded in the rotor core and a stator with a three-phase coil wound around the stator core. As described above, the rotor of the motor MG1 is connected to the sun gear 31 of the planetary gear 30. The rotor of the motor MG2 is connected to the drive shaft 37. The inverters 41 and 42 are configured as inverter circuits having multiple switching elements. The inverters 41 and 42 are connected to the battery 50 via a power line 54. A smoothing capacitor is attached to the power line 54. The motors MG1 and MG2 are rotationally driven by a motor electronic control unit (hereinafter referred to as "motor ECU") 40 controlling the switching of the multiple switching elements of the inverters 41 and 42.

[0018] The motor ECU 40 includes a microcomputer, similar to the engine ECU 24. The motor ECU 40 receives signals from various sensors via input ports. For example, the motor ECU 40 receives rotational positions θm1 and θm2 from rotational position sensors 43 and 44, which detect the rotational positions of the rotors of the motors MG1 and MG2; phase currents Iu1, Iv1, Iw1, Iu2, Iv2, and Iw2 from current sensors, which detect the phase currents of the respective phases of the motors MG1 and MG2; and a temperature αm1 from a temperature sensor 45, which detects the temperature of the motor MG1. The temperature sensor 45 may be, for example, a sensor that detects the temperature αm1 of the permanent magnets of the motor MG1, the coils of the motor MG1, or the lubricating oil that cools the motor MG1. The motor ECU 40 outputs various control signals via output ports. For example, the motor ECU 40 outputs control signals to the inverters 41 and 42. The motor ECU 40 calculates the electrical angles θe1, θe2 and rotation speeds Nm1, Nm2 of the motors MG1, MG2 based on the rotational positions θm1, θm2 of the rotors of the motors MG1, MG2. The motor ECU 40 communicates with the HVECU .

[0019] The battery 50 is configured as, for example, a lithium ion secondary battery or a nickel-metal hydride secondary battery. As described above, the battery 50 is connected to the inverters 41 and 42 via a power line 54. The battery 50 is managed by a battery electronic control unit (hereinafter referred to as "battery ECU") 52.

[0020] The battery ECU 52 includes a microcomputer, similar to the engine ECU 24. The battery ECU 52 receives signals from various sensors via an input port. For example, the battery ECU 52 receives a voltage Vb from a voltage sensor 51v attached between the terminals of the battery 50, a current Ib from a current sensor 51i attached to the output terminals of the battery 50, and a temperature Tb from a temperature sensor 51t attached to the battery 50. The battery ECU 52 calculates the battery 50's power storage percentage SOC based on the integrated value of the battery 50's current Ib, and calculates input / output limits Win and Wout, which are the allowable input / output power of the battery 50, based on the power storage percentage SOC and the temperature Tb. The input / output limits Win and Wout are set so that their absolute values ​​decrease as the temperature Tb moves away from the allowable temperature range toward the lower side. The battery ECU 52 communicates with the HVECU 70.

[0021] The HVECU 70 includes a microcomputer, similar to the engine ECU 24. The HVECU 70 receives signals from various sensors via input ports. For example, the HVECU 70 receives a signal from a power switch 80, a shift position SP from a shift position sensor 82 that detects the operating position of a shift lever 81, an accelerator opening Acc from an accelerator pedal position sensor 84 that detects the depression amount of an accelerator pedal 83, a brake pedal position BP from a brake pedal position sensor 86 that detects the depression amount of a brake pedal 85, and a vehicle speed V from a vehicle speed sensor 87. As described above, the HVECU 70 communicates with the engine ECU 24, the motor ECU 40, and the battery ECU 52.

[0022] In the hybrid vehicle 20 of this embodiment, the engine 22 and the motors MG1 and MG2 are controlled to perform hybrid running (HV running) or electric running (EV running) through cooperative control between the HVECU 70, the engine ECU 24, and the motor ECU 38. HV running is running with the engine 22 in operation. EV running is running with the engine 22 stopped (not in operation).

[0023] In HV traveling, the HVECU 70 first sets a required torque Td* for traveling (required of the drive shaft 37) based on the accelerator opening Acc and the vehicle speed V, and then sets a required power Pd* for traveling based on the set required torque Td* and the rotation speed Nd of the drive shaft 37 (rotation speed Nm2 of the motor MG2). Next, the HVECU 70 sets a required power Pe* for the engine 22 based on the required power Pd* and a required charge / discharge power Pb* based on the power storage rate SOC of the battery 50, and then sets a target rotation speed Ne* and target torque Te* for the engine 22 and torque commands Tm1* and Tm2* for the motors MG1 and MG2 so that the required power Pe* is output from the engine 22 and the required torque Td* is output to the drive shaft 37 within the input / output limits Win and Wout of the battery 50. The engine ECU 24 transmits the target rotation speed Ne* and target torque Te* of the engine 22 to the engine ECU 24, and also transmits torque commands Tm1* and Tm2* of the motors MG1 and MG2 to the motor ECU 40. The engine ECU 24 performs operation control (intake air amount control, fuel injection control, ignition control, etc.) of the engine 22 so that the engine 22 operates based on the target rotation speed Ne* and the target torque Te*. The motor ECU 40 controls the inverters 41 and 42 so that the motors MG1 and MG2 are driven based on the torque commands Tm1* and Tm2*.

[0024] In HV driving, when the stop conditions for engine 22 are met, such as when vehicle speed V is less than threshold Vref1, required torque Td* is less than threshold Tdref, and required power Pd* is less than threshold Pdref, engine 22 is stopped and the vehicle transitions to EV driving.

[0025] In EV driving, the HVECU 70 first sets the required torque Td* in the same way as in HV driving. Next, the HVECU 70 sets the torque command Tm1* for the motor MG1 to a value of 0, and sets the torque command Tm2* for the motor MG2 to the required torque Td* so that the required torque Td* is output to the drive shaft 37 within the input / output limits Win and Wout of the battery 50. The HVECU 70 then transmits the torque commands Tm1* and Tm2* for the motors MG1 and MG2 to the motor ECU 40. The motor ECU 40 controls the inverters 41 and 42 so that the motors MG1 and MG2 are driven by the torque commands Tm1* and Tm2*.

[0026] In EV driving, when a start condition for the engine 22 is met, such as when the vehicle speed V reaches or exceeds a threshold Vref1 (start determination vehicle speed), when the required torque Td* reaches or exceeds a threshold Tdref, or when the required power Pd* calculated in the same manner as in HV driving reaches or exceeds a threshold Pdref, the engine 22 is started by cranking the engine 22 using the motor MG1, and the vehicle transitions to HV driving. When starting the engine 22, the motor MG1 (inverter 41) is controlled by setting a cranking torque Tcr for cranking the engine 22 as the torque command Tm1* for the motor MG1. When the rotation speed Ne of the engine 22 reaches or exceeds a threshold Nsteg, fuel injection control, ignition control, and the like for the engine 22 are initiated. The motor MG2 (inverter 42) is controlled by setting a torque command Tm2* so that the required torque Td* is output to the drive shaft 37 within the input / output limits Win and Wout of the battery 50.

[0027] Here, the cranking torque Tcr can be set, for example, as follows. FIG. 2 is an explanatory diagram showing an example of a method for setting the cranking torque Tcr. In the example of FIG. 2, when a start condition for the engine 22 is met (time t1), the cranking torque Tcr is increased from a value of 0 to a relatively large first torque Tcr1 by rate processing and maintained at that value. This allows the rotation speed Ne of the engine 22 to increase quickly and quickly pass through a resonance band (for example, approximately 400 rpm to 600 rpm). Then, when a decrease start condition is met (time t2), the cranking torque Tcr is decreased from the first torque Tcr1 to a smaller second torque Tcr2 and maintained at that value. This makes it possible to suppress power consumption of the motor MG1. The decrease start condition includes a rotation speed condition in which the rotation speed Ne of the engine 22 is equal to or greater than a rotation speed Nstmg that is slightly higher than the resonance band. Furthermore, when the rotation speed Ne of the engine 22 reaches or exceeds the threshold value Nsteg (time t3), the cranking torque Tcr is reduced from the second torque Tcr to a value of 0, and when the engine 22 completely explodes and the start-up of the engine 22 is completed, the torque from the engine 22 is used to generate electricity by the motor MG1.

[0028] 3 is an explanatory diagram showing an example of the relationship between the rotational speeds of the rotating elements of the planetary gear 30 when starting the engine 22. In the diagram, the S-axis represents the rotational speed of the sun gear 31, which is the rotational speed Nm1 of the motor MG1; the C-axis represents the rotational speed of the carrier 34, which is the rotational speed Ne of the engine 22; and the R-axis represents the rotational speed of the ring gear 32, which is the rotational speed Nd of the drive shaft 37 (the rotational speed Nm2 of the motor MG2). In the diagram, the solid line represents the nomogram when the engine 22 begins to start, and the dashed line represents the nomogram when the engine 22 has finished starting. As can be seen from FIG. 3, the motor MG1 is regeneratively driven at the beginning of cranking the engine 22, and is power-driven after the rotational speed Ne of the motor MG1 crosses the value 0. Note that the higher the vehicle speed V (the rotation speed Nd of the drive shaft 36), the smaller (more negative) the rotation speed Nm1 of the motor MG1 when starting the engine 22, and therefore the greater the power generated by regenerative driving of the motor MG1 at the beginning of cranking the engine 22, and the greater the input power to the battery 50. In light of this, the threshold value Vref1 (start determination vehicle speed) described above is set so that the input power to the battery 50 when starting the engine 22 while traveling is within the range of the input limit Win. As described above, the input limit Win of the battery 50 is set so that its absolute value decreases as the temperature Tb of the battery 50 moves away from the allowable temperature range toward the lower side, and therefore the threshold value Vref1 (start determination vehicle speed) is also set so that it decreases as the temperature Tb decreases.

[0029] Next, the operation of the hybrid vehicle 20 of this embodiment, particularly the process for setting the first torque Tcr1 and the decrease start condition, will be described. Fig. 4 is a flowchart showing an example of a processing routine executed by the HVECU 70. This routine is executed when a start condition for the engine 22 is met while the hybrid vehicle 20 is running in EV mode.

[0030] 4 is executed, the HVECU 70 first inputs the temperature αm1 of the motor MG1 and the vehicle speed V (step S100). Here, the temperature αm1 of the motor MG1 is detected by the temperature sensor 45 and input by communication from the motor ECU 40. The vehicle speed V is detected by the vehicle speed sensor 87 and input.

[0031] Next, it is determined whether the temperature αm1 of the motor MG1 is less than a threshold value αm1ref (step S110). Here, the threshold value αm1ref is used to determine whether the actual torque Tm1 of the motor MG1 can be somewhat larger than the torque command Tm1*. As the threshold value αm1ref, for example, a temperature of approximately 0°C to -30°C is used. The torque of the motor MG1 is composed of magnet torque and reluctance torque, and the inventors have confirmed through extensive research that, for the motor MG1, the lower the temperature αm1 is, the larger the magnet torque and therefore the larger the actual torque Tm1 is, for the same torque command Tm1*. The processing of step S110 is based on this.

[0032] If it is determined that the temperature αm1 of the motor MG1 is equal to or greater than the threshold αm1ref, it is determined that the actual torque Tm1 of the motor MG1 will not be significantly larger than the torque command Tm1*, and a predetermined value Tcr11 is set as the first torque Tcr1 (step S120), and the process proceeds to step S140. On the other hand, if it is determined that the temperature αm1 of the motor MG1 is less than the threshold αm1ref, it is determined that the actual torque Tm1 of the motor MG1 may be somewhat larger than the torque command Tm1*, and a predetermined torque Tcr12 smaller than the predetermined value Tcr11 is set as the first torque Tcr1 (step S130), and the process proceeds to step S140.

[0033] In this way, when the temperature αm1 of the motor MG1 is below the threshold αm1ref, the cranking torque Tcr, i.e., the torque command Tm1*, is set by reducing the first torque Tcr1 compared to when the temperature αm1 of the motor MG1 is equal to or greater than the threshold αm1ref. This prevents the actual torque Tm1 of the motor MG1 from becoming larger when the temperature αm1 of the motor MG1 is below the threshold αm1ref compared to when the temperature αm1 of the motor MG1 is equal to or greater than the threshold αm1ref. Therefore, when the temperature αm1 of the motor MG1 is below the threshold αm1ref, the generated power due to regenerative driving of the motor MG1 is prevented from becoming relatively large at the beginning of cranking of the engine 22, particularly when the first torque Tcr1 is set to the cranking torque Tcr, i.e., the torque command Tm1*, and the input power of the battery 50 is prevented from becoming relatively large. As a result, when the temperature αm1 of the motor MG1 is below the threshold αm1ref, the threshold Vref1 (start-up determination vehicle speed) is prevented from being set relatively low, preventing the allowable vehicle speed range for EV driving from becoming narrow.

[0034] After the first torque Tcr1 is set in step S120 or step S130, it is determined whether the vehicle speed V is equal to or greater than a threshold value Vref2 (step S140). The threshold value Vref2 is used to determine whether vibrations occurring when the cranking torque Tcr is reduced from the first torque Tcr1 are likely to be lost in road noise. The threshold value Vref2 is set within a range less than the threshold value Vref1 (start determination vehicle speed), and is, for example, approximately several tens of km / h.

[0035] If the vehicle speed V is determined to be less than the threshold value Vref2, it is determined that any vibrations that occur when the cranking torque Tcr is reduced from the first torque Tcr1 are unlikely to be lost as road noise. Therefore, the reduction start condition is set to include a crank angle condition in which the crank angle θcr is within a predetermined crank angle range (step S150), and the routine ends. In this case, the reduction start condition includes the crank angle condition and the above-mentioned engine speed condition as an AND condition. The predetermined crank angle range is determined in advance through experiments, analysis, machine learning, etc., so that the maximum vibrations that occur when the cranking torque Tcr is reduced from the first torque Tcr1 are within an allowable vibration range. By using such a reduction start condition, it is possible to suppress the occurrence of relatively large vibrations when the cranking torque Tcr is reduced from the first torque Tcr1.

[0036] On the other hand, when the vehicle speed V is determined to be equal to or greater than the threshold value Vref2, it is determined that vibrations occurring when the cranking torque Tcr is reduced from the first torque Tcr1 are likely to be lost as road noise. Therefore, the decrease start condition is set so as not to include the crank angle condition (step S150), and the routine is terminated. This prevents the time until the decrease start condition is satisfied from becoming longer than when the decrease start condition includes the crank angle condition. This prevents the cranking torque Tcr from remaining at the first torque Tcr1 for a longer period of time, and prevents the motor MG1 from maintaining a relatively high level of power (either generated power or consumed power, depending on the rotational speed of the motor MG1). Note that, as the vehicle speed V (rotational speed Nd of the drive shaft 36) increases, the rotational speed Nm1 of the motor MG1 at the start of starting the engine 22 decreases (becomes more negative), making it easier to regeneratively drive the motor MG1 when the cranking torque Tcr is maintained at the first torque Tcr1. By preventing the duration of time when the power (especially the generated power) of motor MG1 remains relatively high, it is possible to set the threshold value Vref1 (start-up determination vehicle speed) higher, thereby expanding the allowable vehicle speed range for EV driving.

[0037] In the hybrid vehicle 20 of the present embodiment described above, when starting the engine 22 by cranking the engine 22 using the motor MG1 while the vehicle is running, the cranking torque Tcr, which increases from 0 to a first torque Tcr1, maintains the first torque Tcr1, and then decreases when a decrease start condition is met, is set as the torque command Tm1* to control the motor MG1 (inverter 41). In this case, when the temperature αm1 of the motor MG1 is below the threshold αm1ref, the first torque Tcr1 is reduced, thereby reducing the cranking torque Tcr compared to when the temperature αm1 of the motor MG1 is equal to or greater than the threshold αm1ref. This prevents the actual torque Tm1 of the motor MG1 from increasing when the temperature αm1 of the motor MG1 is equal to or greater than the threshold αm1ref. Therefore, when the temperature αm1 of the motor MG1 is below the threshold αm1ref, the generated power due to regenerative driving of the motor MG1 is prevented from increasing relatively at the beginning of cranking of the engine 22, and the input power of the battery 50 is prevented from increasing relatively. As a result, when the temperature αm1 of the motor MG1 is less than the threshold αm1ref, the threshold Vref1 (start determination vehicle speed) is prevented from being set relatively low, and the allowable vehicle speed range for EV driving can be prevented from narrowing.

[0038] Furthermore, in the hybrid vehicle 20 of this embodiment, when the vehicle speed V is below the threshold Vref2, the decrease start condition is set to include a crank angle condition, and when the vehicle speed V is equal to or greater than the threshold Vref2, the decrease start condition is set to not include a crank angle condition. This makes it possible to prevent the duration of a state in which the electric power (particularly the generated electric power) of the motor MG1 is relatively high from becoming long when the vehicle speed V is equal to or greater than the threshold Vref2. As a result, it becomes possible to further increase the threshold Vref1 (start determination vehicle speed), thereby expanding the allowable vehicle speed range for EV driving.

[0039] In the above-described embodiment, when the temperature αm1 of the motor MG1 is less than the threshold value αm1ref, the predetermined torque Tcr12 is set to the first torque Tcr1. However, this is not limiting. For example, the first torque Tcr1 may be set within a range less than the predetermined torque Tcr11 using the temperature αm1 of the motor MG1 and a low-temperature map. The low-temperature map is determined in advance as a relationship between the temperature αm1 of the motor MG1 and the first torque Tcr1 through experimentation, analysis, machine learning, or the like. In this case, the first torque Tcr1 can be set by applying the temperature αm1 of the motor MG1 to the low-temperature map and deriving the corresponding first torque Tcr1 from the low-temperature map. FIG. 5 is an explanatory diagram showing an example of the low-temperature map. As shown in FIG. 5, the first torque Tcr1 is determined to decrease as the temperature αm1 of the motor MG1 decreases within a range less than the predetermined torque Tcr1. As a result, when the temperature αm1 of the motor MG1 is below the threshold αm1ref, the actual torque Tm1 of the motor MG1 can be more appropriately prevented from increasing compared to when the temperature αm1 of the motor MG1 is equal to or greater than the threshold αm1ref. Therefore, when the temperature αm1 of the motor MG1 is below the threshold αm1ref, the generated power due to the regenerative driving of the motor MG1 can be more appropriately prevented from increasing relatively at the beginning of cranking of the engine 22, and the input power of the battery 50 can be more appropriately prevented from increasing relatively.

[0040] In the above-described embodiment, when the temperature αm1 of the motor MG1 is below the threshold value αm1ref, the cranking torque Tcr is reduced by reducing the first torque Tcr1 compared to when the temperature αm1 of the motor MG1 is equal to or greater than the threshold value αm1ref. However, this is not limiting. For example, when the temperature αm1 of the motor MG1 is equal to or greater than the threshold value αm1ref, the cranking torque Tcr may be set as shown in Fig. 2, and when the temperature αm1 of the motor MG1 is below the threshold value αm1ref, the cranking torque Tcr may be set by multiplying the cranking torque Tcr when the temperature αm1 of the motor MG1 is equal to or greater than the threshold value αm1ref by a correction coefficient kcr that is smaller than 1.

[0041] In the above-described embodiment, the decrease start condition is set to include the crank angle condition when the vehicle speed V is less than the threshold Vref2, and is set to not include the crank angle condition when the vehicle speed V is equal to or greater than the threshold Vref2. However, the decrease start condition may be set to include the crank angle condition regardless of the vehicle speed V.

[0042] In the above-described embodiment, the hybrid vehicle 20 is provided with the battery 50 as the power storage device, but is not limited to this. For example, the hybrid vehicle 20 may be provided with a capacitor or the like as the power storage device.

[0043] In the above-described embodiment, the hybrid vehicle 20 includes the engine ECU 24, the motor ECU 40, the battery ECU 52, and the HVECU 70. However, the present invention is not limited to this. For example, at least two of the engine ECU 24, the motor ECU 40, the battery ECU 52, and the HVECU 70 may be integrated.

[0044] Although not specifically described in the above embodiment, the hybrid vehicle 20 may be configured to be rechargeable using electric power from an external power source.

[0045] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be described below. In the embodiment, the engine 22 corresponds to the "engine," the motor MG1 corresponds to the "first motor," the planetary gear 30 corresponds to the "planetary gear," the motor MG2 corresponds to the "second motor," the battery 50 corresponds to the "electricity storage device," and the engine ECU 24, the motor ECU 40, and the HVECU 70 correspond to the "control device."

[0046] The correspondence between the main elements of the embodiments and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the embodiments are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the embodiments are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0047] The above describes the forms for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0048] The present disclosure is applicable to the hybrid vehicle manufacturing industry and the like. [Explanation of symbols]

[0049] 20 hybrid vehicle, 22 engine, 23 crankshaft, 23a crank position sensor, 24 engine ECU, 30 planetary gear, 31 sun gear, 32 ring gear, 33 pinion gear, 34 carrier, 37 drive shaft, 38 differential gear, 39a, 39b drive wheels, 40 motor ECU, 41 inverter, 42 inverter, 43 rotational position sensor, 45 temperature sensor, 50 battery, 51i current sensor, 51t temperature sensor, 51v voltage sensor, 52 battery ECU, 54 power line, 70 HVECU, 80 power switch, 81 shift lever, 82 shift position sensor, 83 accelerator pedal, 84 accelerator pedal position sensor, 85 brake pedal, 86 brake pedal position sensor, 87 vehicle speed sensor.

Claims

1. The engine and a first motor; a planetary gear connected to the first motor, the engine, and a drive shaft connected to a drive wheel; a second motor connected to the drive shaft; an electric storage device connected to the first motor and the second motor via a power line; a control device that controls the engine, the first motor, and the second motor so that the vehicle travels with intermittent operation of the engine; A hybrid vehicle comprising: When a start condition is satisfied during running and the engine is started with cranking of the engine by the first motor, if the temperature of the first motor is below a predetermined temperature, the control device controls the first motor by setting a torque command for the first motor that is smaller than that when the temperature of the first motor is equal to or higher than the predetermined temperature. Hybrid car.

2. The hybrid vehicle according to claim 1, the control device sets a start determination vehicle speed so that input power of the power storage device when starting the engine while traveling falls within a range of allowable input power; The start condition includes a condition that the vehicle speed is equal to or higher than the start determination vehicle speed. Hybrid car.

3. 3. The hybrid vehicle according to claim 1 or 2, When starting the engine while the vehicle is running, if the temperature of the first motor is lower than the predetermined temperature, the control device sets the torque command to a smaller value as the temperature of the first motor decreases. Hybrid car.

4. 3. The hybrid vehicle according to claim 1 or 2, When starting the engine while the vehicle is running, the control device sets the torque command so that the torque command is increased to and maintained at a first torque and then decreased when a decrease start condition is met, the decrease start condition includes a crank angle condition that the crank angle of the engine is within a predetermined crank angle range when the vehicle speed is lower than a predetermined vehicle speed, and does not include the crank angle condition when the vehicle speed is equal to or higher than the predetermined vehicle speed. Hybrid car.

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