Hybrid vehicle control device

Abstract

To enable a hybrid vehicle to appropriately make transition to avoidance travel through preventing a restart process of a stalled engine to be repeated.SOLUTION: A hybrid vehicle control device is to control a hybrid vehicle comprising an engine capable of outputting power for traveling, an electric motor capable of outputting power for traveling, and a battery exchanging electric power with the electric motor. The hybrid vehicle control device: determines whether or not a rotation speed of the engine becomes less than a predetermined stall rotation speed; counts the number of times that the rotation speed of the engine is determined to be less than the predetermined stall rotation speed; and causes the hybrid vehicle to perform avoidance travel with the power output only from the electric motor when the counted number of times becomes equal to or larger than a predetermined threshold.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a control device for a hybrid vehicle including an engine and an electric motor capable of outputting driving power respectively.

Background Art

[0002] Conventionally, as a hybrid vehicle including an internal combustion engine, an electric generator, and a battery, when the internal combustion engine has stalled and stopped operating, and a special operation different from the normal driving operation is performed by the driver and an emergency operation signal is output, there is known a control device that causes the hybrid vehicle to perform a retreat running using only the power from the electric generator (see, for example, Patent Document 1). In such a hybrid vehicle, the emergency operation signal is output when the driver performs a stepping operation of the accelerator pedal a preset number of times within a preset time, or when the driver performs a switching operation of the shift lever of the transmission a preset number of times within a preset time.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above conventional hybrid vehicle, even in an emergency, unless the driver performs the above special operation and an emergency operation signal is output, a retreat running that outputs power only from the electric generator is not started. For this reason, in the above conventional hybrid vehicle, even if some abnormality occurs that hinders the restart of the stalled internal combustion engine, the restart process of the internal combustion engine continues to be repeatedly executed, and there is a risk that the vehicle may become inoperable.

[0005] Therefore, the main object of the present disclosure is to suppress the repeated execution of the restart process of a stalled engine and appropriately shift a hybrid vehicle to evacuation driving.

Means for Solving the Problems

[0006] In a control device for a hybrid vehicle including an engine capable of outputting driving power for traveling, an electric motor capable of outputting driving power for traveling, and a battery that exchanges electric power with the electric motor, it is determined whether the rotational speed of the engine has become less than a predetermined stall rotational speed, and the number of times the rotational speed is determined to be less than the stall rotational speed is counted. When the number of times becomes equal to or more than a predetermined threshold value, the hybrid vehicle is caused to perform evacuation driving only by the power from the electric motor.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0008] Next, modes for carrying out the invention of the present disclosure will be described with reference to the drawings.

[0009] FIG. 1 is a schematic configuration diagram showing a hybrid vehicle 1 controlled by the control device of the present disclosure. The hybrid vehicle 1 shown in the figure includes an engine (internal combustion engine) 2, a motor generator MG, a power transmission device 3, a hydraulic clutch K0, a high-voltage battery (high-voltage power storage device) 4, a low-voltage battery (low-voltage power storage device) 5 as an auxiliary battery, and a power control unit (hereinafter referred to as "PCU") 6 that drives the motor generator MG. Further, the hybrid vehicle 1 includes an engine electronic control unit (hereinafter referred to as "EGECU") 20 that controls the engine 2, a transmission electronic control unit (hereinafter referred to as "TMECU") 30 that controls the power transmission device 3, a motor electronic control unit (hereinafter referred to as "MGECU") 60 that controls the PCU 6, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 70 that comprehensively controls the hybrid vehicle 1 by exchanging information with the EGECU 20, the TMECU 30, and the MGECU 60.

[0010] The engine 2 is a multi-cylinder gasoline engine (for example, a V-type 6-cylinder engine) that converts the reciprocating motion of a piston accompanying the combustion of a mixture of gasoline (hydrocarbon-based fuel) and air in a plurality of combustion chambers (cylinders) into the rotational motion of a crankshaft (output shaft) CS, and includes an electronically controlled throttle valve, a plurality of intake valves and exhaust valves, a variable valve mechanism, a plurality of fuel injection valves, a plurality of spark plugs, an exhaust purification device, etc. (all are omitted in the figure). Further, as shown in FIG. 1, the engine 2 includes a starter (engine starting device) ST mainly used for cranking the engine 2 in an extremely low temperature environment and an alternator A driven by the engine 2 to generate electric power. The crankshaft CS of such an engine 2 is connected to the input member of a damper mechanism D (for example, a flywheel damper).

[0011] The EGECU 20 that controls the engine 2 includes a microcomputer having a CPU, ROM, RAM, input / output interfaces, etc. (not shown), various drive circuits, various logic ICs, etc. Further, the EGECU 20 acquires the detection values of various sensors (all not shown in the figure) such as a crank angle sensor, an air flow meter, a throttle opening sensor, an air-fuel ratio sensor, a water temperature sensor, and an accelerator pedal position sensor, and receives a command signal from the HVECU 70. Furthermore, the EGECU 20 calculates the rotational speed Ne of the engine 2 (crankshaft CS) based on the detection value of the crank angle sensor, and calculates the load factor KL based on the rotational speed Ne of the engine 2 and the intake air amount detected by the air flow meter. The EGECU 20 controls a throttle valve, a variable valve mechanism, a plurality of fuel injection valves, ignition plugs, etc. based on the detection values of various sensors, calculated values such as the rotational speed Ne, and a command signal from the HVECU 70.

[0012] The motor generator MG is a synchronous generator motor (three-phase AC motor) including a rotor in which permanent magnets are embedded and a stator around which a three-phase coil is wound, and exchanges power with the high-voltage battery 4 via the PCU 6. The motor generator MG operates as an electric motor that is driven by the power from the high-voltage battery 4 to generate drive torque, and outputs a regenerative braking torque when the hybrid vehicle 1 brakes. Further, the motor generator MG also operates as a generator that generates power using at least a part of the power from the engine 2 that is under load operation. As shown in FIG. 1, the rotor of the motor generator MG is fixed to the transmission shaft TS.

[0013] The power transmission device 3 includes a torque converter (fluid transmission device) 31 having a torque amplification function, a lock-up clutch 32, a mechanical oil pump 33, an electric oil pump 34, a transmission (automatic transmission) 35, a hydraulic control device 36 for regulating the hydraulic pressure of the working oil, and the like. The torque converter 31 includes a pump impeller connected to the transmission shaft TS via a front cover (input member), a turbine runner connected to the input shaft 35i of the transmission 35, and a stator that rectifies the flow of the working oil from the turbine runner to the pump impeller to amplify the torque. The lock-up clutch 32 is a multi-plate friction type or single-plate friction type hydraulic clutch that connects the front cover and the input shaft 35i of the transmission 35 and releases the connection between the two.

[0014] The transmission 35 is, for example, a four-speed to ten-speed multi-stage transmission including an input shaft 35i, an output shaft 35o, a plurality of planetary gears, and a plurality of clutches and brakes (shift engagement elements) respectively. The transmission 35 shifts the power transmitted to the input shaft 35i from the transmission shaft TS via either the torque converter 31 or the lock-up clutch 32 in multiple stages and outputs it to the left and right wheels (drive wheels) W via the differential gear DF and the drive shaft DS from the output shaft 35o. The hydraulic control device 36 includes a valve body in which a plurality of oil passages are formed, a plurality of regulator valves, a plurality of linear solenoid valves, and the like. The hydraulic control device 36 regulates the hydraulic pressure of the working oil (hydraulic pressure) from at least one of the mechanical oil pump 33 and the electric oil pump 34 and supplies it to the torque converter 31, the lock-up clutch 32, the clutches and brakes of the transmission 35, and the like.

[0015] The TMECU 30 that controls the power transmission device 3 includes a microcomputer having a CPU, ROM, RAM, input / output interfaces, etc. (not shown), various drive circuits, various logic ICs, etc. Further, the TMECU 30 acquires detection values of various sensors such as a shift position sensor, an accelerator pedal position sensor, an input rotation speed sensor that detects the rotation speed of the input shaft 35i, an output rotation speed sensor that detects the rotation speed of the output shaft 35o, and a vehicle speed sensor (all not shown), and receives a command signal, etc. from the HVECU 70. The TMECU 30 controls the power transmission device 3, that is, the hydraulic control device 36, based on the detection values of various sensors and the command signal, etc. from the HVECU 70.

[0016] The clutch K0 connects and disconnects the output member of the damper mechanism D, that is, the crankshaft CS of the engine 2, and the transmission shaft TS, that is, the rotor of the motor generator MG, according to the hydraulic pressure supplied from a second hydraulic control device 37 different from the above-mentioned hydraulic control device 36. In the present embodiment, the clutch K0 is a normally open hydraulic clutch that is released as the engagement hydraulic pressure supplied from the second hydraulic control device 37 decreases and engages as the engagement hydraulic pressure increases. When the clutch K0 engages, the engine 2 (crankshaft CS) is connected to the motor generator MG via the clutch K0.

[0017] Thereby, the engine 2 is connected to the left and right wheels W via the damper mechanism D, the clutch K0, the transmission shaft TS (motor generator MG), the power transmission device 3, etc. The clutch K0 may be disposed inside the rotor of the motor generator MG or may be disposed between the damper mechanism D and the motor generator MG in the axial direction. Further, in the present embodiment, the second hydraulic control device 37 that supplies hydraulic pressure to the clutch K0 is disposed, for example, below the motor generator MG, and is controlled by the HVECU 70 to regulate the hydraulic pressure from at least one of the mechanical oil pump 33 and the electric oil pump 34 and supply and discharge hydraulic pressure to the clutch K0.

[0018] The high-voltage battery 4 is, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery having a rated output voltage of about 200 to 300 V. However, the high-voltage battery 4 may be a capacitor, or may include both a secondary battery and a capacitor. The low-voltage battery 5 is, for example, a lead-acid battery having a rated output voltage of 12 V, and is charged by the power from the alternator A or the like. The low-voltage battery 5 supplies power to auxiliary machines such as the starter ST of the engine 2, the electric oil pump 34, and the hydraulic control devices 36, 37, and electronic devices such as various ECUs.

[0019] The PCU 6 includes an inverter, a boost converter, a DC / DC converter, etc. (all not shown in the figure) for driving the motor generator MG, and is connected to the high-voltage battery 4 via the system main relay SMR and is also connected to the low-voltage battery 5. The inverter includes, for example, six transistors as switching elements and six diodes connected in parallel in the reverse direction to these transistors. The boost converter boosts the voltage from the high-voltage battery 4 and supplies it to the inverter, and also steps down the voltage from the inverter and supplies it to the high-voltage battery 4. The DC / DC converter steps down the power from the high-voltage battery 4 or the inverter and supplies it to the low-voltage system, that is, the low-voltage battery 5 and various auxiliary machines.

[0020] The MGECU 60 includes a microcomputer having a CPU, ROM, RAM, input / output interfaces, etc. (not shown), various drive circuits, various logic ICs, etc. The MGECU 60 acquires the pre-boost voltage and post-boost voltage of the boost converter, the rotational position of the rotor (transmission shaft TS) of the motor generator MG detected by a rotational position sensor (resolver, not shown), the phase current applied to the motor generator MG, etc., and receives command signals, etc. from the HVECU 70. The MGECU 60 performs switching control of the inverter and the boost converter based on these detected values, command signals from the HVECU 70, etc. Further, the MGECU 60 calculates the rotational speed Nm (rpm) of the rotor (transmission shaft TS) of the motor generator MG based on the detected value of the rotational position sensor at predetermined intervals (microscopic intervals), and calculates the angular velocity ωm and angular acceleration αm of the rotor.

[0021] The HVECU 70 includes a microcomputer having a CPU, ROM, RAM, input / output interfaces, etc. (not shown), various drive circuits, various logic ICs, etc. The HVECU 70 acquires a signal from the start switch (IG switch), the accelerator opening Acc (the amount of depression of the accelerator pedal) detected by the accelerator pedal position sensor, the vehicle speed V detected by the vehicle speed sensor, the gear ratio γ of the transmission 35 corresponding to the accelerator opening Acc and the vehicle speed V, the rotational speed Nm of the motor generator MG from the MGECU 60, etc. Further, the HVECU 70 acquires the SOC of the high-voltage battery 4, the target charge / discharge power Pb*, the allowable charge power Win, the allowable discharge power Wout, etc. calculated by the power management device (power management ECU, not shown) from the power management device. The HVECU 70 sets the target power Pe* and target rotational speed Ne* of the engine 2, command values to the power transmission device 3 (hydraulic control device 36), torque command value Tm* to the motor generator MG, etc. based on this information, and controls the clutch K0 (second hydraulic control device 37).

[0022] In the hybrid vehicle 1 configured as described above, when the mechanical oil pump 33 and the electric oil pump 34 are not generating hydraulic pressure due to system stop (while parked), the normally open clutch K0 is released, disconnecting the connection between the engine 2 and the transmission shaft TS, i.e., the motor generator MG. Then, after the system is started, the hybrid vehicle 1 basically starts by the torque (power) from the motor generator MG output to the power transmission device 3 as the drive system via the transmission shaft TS with the clutch K0 released.

[0023] Also, while the hybrid vehicle 1 is stopped (including while parked) or while the hybrid vehicle 1 is running by the torque from the motor generator MG, the HVECU 70 determines whether or not a predetermined engine start condition is satisfied. When the HVECU 70 determines that the engine start condition is satisfied, it executes a start process in a manner corresponding to the running state of the hybrid vehicle 1 to start the engine 2 and engage the clutch K0. The start process of the engine 2 basically drives the motor generator MG with the power from the high-voltage battery 4 so as to output a cranking torque for starting the engine 2 while slipping and engaging the clutch K0. Thereby, after the start of the engine 2 is completed, while operating the engine 2 at an operating point near the optimal fuel consumption line, for example, the high-voltage battery 4 can be charged with the power generated by the motor generator MG according to the SOC of the high-voltage battery 4, or the motor generator MG can be driven with the power from the high-voltage battery 4 to output torque to the wheels W from both the engine 2 and the motor generator MG. Therefore, in the hybrid vehicle 1, it is possible to improve the fuel consumption of the engine 2 while ensuring good power performance.

[0024] Furthermore, during the operation of engine 2, the HVECU 70 determines whether or not a predetermined engine stop condition is satisfied. When the HVECU 70 determines that the engine stop condition is satisfied, it executes the operation stop process of engine 2 and releases the clutch K0. As a result, engine 2 can be intermittently stopped according to the state of the hybrid vehicle 1, improving the fuel efficiency of engine 2 and further improving the energy efficiency in the hybrid vehicle 1. After the operation of engine 2 is stopped in response to the satisfaction of the engine stop condition, the above start process (restart process) is executed in response to the satisfaction of the engine start condition, and the engine 2 is restarted again.

[0025] Also, during the operation of engine 2, the EGECU 20 performs abnormal diagnosis of components (elements) such as a crank angle sensor, an air flow meter, a throttle opening sensor, an air-fuel ratio sensor, a water temperature sensor, a fuel injection valve, an ignition plug, and a variable valve mechanism used at the start or idle control of the engine 2 at a predetermined timing. When the EGECU 20 determines that all components related to the start of engine 2 are normal by the abnormal diagnosis, it sets the engine operation stop prohibition flag F to "0". Further, when the EGECU 20 determines that an abnormality such as a failure has occurred in any of the components, it sets the engine operation stop prohibition flag F to "1" and turns on a predetermined warning light (MIL warning light) on a display screen or the like installed on an instrument panel or the like. When the engine operation stop prohibition flag F is set to "0" by the EGECU 20, the operation stop (intermittent operation) of engine 2 in response to the satisfaction of the above engine operation stop condition is permitted. On the other hand, when the engine operation stop prohibition flag F is set to "1" by the EGECU 20, the operation stop of engine 2 in response to the satisfaction of the engine operation stop condition is prohibited, and the output of drive torque (assist torque) exceeding the torque for charging the auxiliary machine by the motor generator MG is prohibited.

[0026] That is, when an abnormality (failure) occurs in any of the components related to the start-up of the engine 2, etc., when the engine 2 is restarted after the operation is stopped, for example, the engine 2 may stall due to a shortage of fuel supplied to each combustion chamber, etc., and there is a risk that the restart process of the engine 2 will be continuously and repeatedly executed. In view of this, in the hybrid vehicle 1, when a failure occurs in a component related to the start-up of the engine 2 during the operation of the engine 2, the operation stop (intermittent operation) of the engine 2 is prohibited. Also, when the engine 2 stalls due to a failure of the above components, it is preferable to quickly move the hybrid vehicle 1 to a safe place. For this reason, in the hybrid vehicle 1, in order to appropriately shift the hybrid vehicle 1 to the evacuation driving in response to the occurrence of a stall caused by an abnormality in a component related to the start-up of the engine 2, etc., the routine shown in FIG. 2 is repeatedly executed by the HVECU 70 at predetermined time intervals (micro time intervals).

[0027] At the start of the routine in FIG. 2, the HVECU 70 acquires data necessary for processing, such as the rotational speed Ne of the engine 2 from the EGECU 20 and the value of the above-described engine operation stop prohibition flag F (step S100). Next, the HVECU 70 determines whether or not the acquired rotational speed Ne of the engine 2 is less than a predetermined stall rotational speed Nestl (step S110). In the present embodiment, the stall rotational speed Nestl, which is the threshold value used in step S110, is set to about 150 rpm, for example, at which the engine 2 can be considered to have stalled. When it is determined in step S110 that the rotational speed Ne is equal to or higher than the stall rotational speed Nestl (step S110: NO), the HVECU 70 considers that the engine 2 has not stalled, and immediately ends the routine in FIG. 2 at that point without executing the processing after step S110.

[0028] Also, when it is determined in step S110 that the rotational speed Ne is less than the stall rotational speed Nestl (step S110: YES), the HVECU 70 regards that the engine 2 has stalled, and increments a counter Cestl indicating the number of occurrences of the stall of the engine 2 (step S120). Note that the counter Cestl is reset when the running of the hybrid vehicle 1 ends and the start switch is turned off, and becomes "0" when the start switch is turned on. Also, in the hybrid vehicle 1, the clutch K0 is released when the rotational speed Ne becomes less than the stall rotational speed Nestl.

[0029] After incrementing the counter Cestl in step S120, the HVECU 70 determines whether the engine stop (intermittent operation) of the engine 2 is permitted based on the value of the engine operation stop prohibition flag F acquired in step S100 (step S130). When it is determined in step S130 that the value of the engine operation stop prohibition flag F is "0" and the engine stop (intermittent operation) of the engine 2 is permitted (step S130: YES), the HVECU 70 sets a determination threshold Cref to be compared with the counter Cestl to a predetermined value C1 (step S140). In the present embodiment, the value C1 is a positive integer of about "3" to "5", for example. Also, when it is determined in step S130 that the value of the engine operation stop prohibition flag F is "1" and the engine stop (intermittent operation) of the engine 2 is prohibited (step S130: NO), the HVECU 70 sets the determination threshold Cref to be compared with the counter Cestl to a value C0 determined to be smaller than the value C1 (step S145). In the present embodiment, the value C0 is a positive integer such as "1" or "2", for example.

[0030] After the processing of step S140 or S145, the HVECU 70 determines whether the counter Cestl is equal to or greater than the determination threshold value Cref set in step S140 or S145 (step S150). If it is determined in step S150 that the counter Cestl is less than the determination threshold value Cref (step S150: NO), the HVECU 70 regards that even if the engine 2 stalls, it is a temporary stall, and without executing the processing after step S150, the routine in FIG. 2 is temporarily terminated at that point.

[0031] On the other hand, if it is determined in step S150 that the counter Cestl is equal to or greater than the determination threshold value Cref (step S150: YES), the HVECU 70 regards that there is a possibility of failure to restart the stalled engine 2 even if it attempts to restart the engine 2, and prohibits the restart (execution of the starting process) of the engine 2 (step S160). Further, the HVECU 70 turns on the MG evacuation travel flag so as to evacuate and travel the hybrid vehicle 1 only by the torque (power) from the motor generator MG, and displays a warning such as "Please stop on the shoulder and shift to the P range." on a display screen or the like installed on the instrument panel or the like (step S170), and temporarily terminates the routine in FIG. 2. After prohibiting the restart (operation) of the engine 2 in step S160 and turning on the MG evacuation travel flag in step S170, the HVECU 70 controls the PCU 6 in cooperation with the MGECU 60 so that the motor generator MG outputs the torque required for the travel of the hybrid vehicle 1 with the clutch K0 released.

[0032] As described above, the HVECU 70 as a control device of the hybrid vehicle 1 counts the number of times it is determined that the engine speed Ne of the engine 2 has become less than a predetermined stall speed Nestl, and when a counter Cestl indicating the number of occurrences of stalling of the engine 2 becomes equal to or greater than a predetermined determination threshold Cref (value C1 or C0), the hybrid vehicle 1 is caused to perform a retreat running only by the torque (power) from the motor generator MG (steps S100 - S170). Thereby, it is possible to suppress the continuous repeated execution of the restart process of the stalled engine 2, and it becomes possible to appropriately shift to the retreat running without making the hybrid vehicle 1 unable to run.

[0033] Also, when the operation stop of the engine 2 is prohibited due to an abnormality (failure) of a component related to the start or the like of the engine 2 (step S130: NO), the HVECU 70 sets a determination threshold Cref to be compared with the counter Cestl to be smaller than when the operation stop of the engine 2 is not prohibited due to the abnormality of the component (step S130: YES, S140) (step S145). That is, when the operation stop of the engine 2 is prohibited due to an abnormality of a component related to the start or the like of the engine 2, there is a high possibility that the stalled engine 2 cannot be restarted. Based on this, by setting the determination threshold Cref to a smaller value C0 in step S145, it is possible to quickly shift the hybrid vehicle 1 to a retreat running in which torque is output only from the motor generator MG when the number of occurrences of stalling of the engine 2, that is, the counter Cestl, is smaller. Thereby, it becomes possible to favorably suppress the slippage of the hybrid vehicle 1 on an uphill road before shifting to the retreat running and the delay in releasing the lock-up clutch 32 when the hybrid vehicle 1 suddenly stops.

[0034] Furthermore, in the hybrid vehicle 1, the motor generator MG outputs cranking torque for starting the engine 2 by consuming electric power from the high-voltage battery 4 in response to a start request for the engine 2. In such a hybrid vehicle 1, when the number of times the rotational speed Ne of the engine 2 is determined to be less than the stall rotational speed Nestl, that is, when the counter Cestl becomes equal to or greater than the determination threshold value Cref, the hybrid vehicle 1 is shifted to a retreat running mode in which torque is output only from the motor generator MG, so that the SOC of the high-voltage battery 4 can be favorably suppressed from decreasing (depleting) due to repeated cranking of the engine 2 by the motor generator MG.

[0035] Also, the hybrid vehicle 1 includes a transmission 35 connected to the motor generator MG, and a clutch K0 that connects the engine 2 and the motor generator MG and releases the connection between the two. Thereby, it becomes possible to smoothly perform the retreat running of the hybrid vehicle 1 by releasing the clutch K0 and disconnecting the engine 2 from the motor generator MG.

[0036] Note that the engine 2 of the hybrid vehicle 1 may be a diesel engine, an LPG engine, a biofuel engine, or the like. Also, the hybrid vehicle 1 may be a four-wheel drive vehicle including a transfer that can distribute and transmit torque from the output shaft 35o of the transmission 35 to the differential gear DF and another differential gear. Further, the transmission 35 may be a mechanical continuously variable transmission, a dual clutch transmission, or the like. Also, a clutch for connecting and disconnecting the rotor of the motor generator MG and the transmission shaft TS may be disposed therebetween. Further, the alternator A may be omitted from the hybrid vehicle 1. Also, the functions of the EGECU 20, the TMECU 30, and the HVECU 70 may be integrated into one or two or more electronic control units.

[0037] As described above, in a control device (60, 70) for a hybrid vehicle (1) including an engine (2) capable of outputting driving power for traveling, an electric motor (MG) capable of outputting driving power for traveling, and a battery (4) that exchanges power with the electric motor (MG), it is determined whether or not the rotational speed (Ne) of the engine is less than a predetermined stall rotational speed (Nestl), and the number of times (Cestl) that the rotational speed (Ne) is determined to be less than the stall rotational speed (Nestl) is counted. When the number of times (Cestl) becomes equal to or greater than a predetermined threshold value (Cref, C1, C0), the hybrid vehicle (1) is caused to perform a retreat travel using only the power from the electric motor (MG).

[0038] The control device for a hybrid vehicle of the present disclosure counts the number of times it is determined that the rotational speed of the engine is less than a predetermined stall rotational speed, and when the number of times becomes equal to or greater than a predetermined threshold value, causes the hybrid vehicle to perform a retreat travel using only the power from the electric motor. As a result, it is possible to suppress the restart process of the stalled engine from being continuously and repeatedly executed, and it is possible to appropriately shift to a retreat travel without making the hybrid vehicle unable to travel.

[0039] Further, when the operation stop of the engine (2) is prohibited due to an abnormality of an element related to the start of the engine (2) (step S130: NO), the control device (70) may set the threshold value (Cref) to be smaller (step S145) than when the operation stop of the engine is not prohibited due to the abnormality of the element (step S130: YES, S140).

[0040] That is, when the operation stop of the engine is prohibited due to an abnormality of an element related to the start of the engine, since there is a high possibility that the stalled engine cannot be restarted, by reducing the threshold value, it is possible to quickly shift the hybrid vehicle to a retreat travel in which power is output only from the electric motor in response to the occurrence of an engine stall.

[0041] Furthermore, the electric motor (MG) may output a cranking torque for starting the engine (2) by consuming electric power from the battery (4) in response to a starting request for the engine (2).

[0042] In such a hybrid vehicle, when the number of times it is determined that the engine speed has fallen below the stall speed reaches or exceeds a predetermined threshold, the hybrid vehicle is shifted to a retreat running mode in which power is output only from the electric motor, thereby suppressing a decrease in the SOC of the battery due to continuous and repeated cranking of the engine by the electric motor.

[0043] Further, the hybrid vehicle (1) may include a transmission (35) connected to the electric motor (MG), and a clutch (K0) that connects and disconnects the engine (2) and the electric motor (MG).

[0044] Thereby, it becomes possible to smoothly perform the retreat running of the hybrid vehicle by releasing the clutch and disconnecting the engine from the electric motor.

[0045] The invention of the present disclosure is not limited to the above embodiments, and it goes without saying that various changes can be made within the scope of the extension of the present disclosure. Furthermore, the above embodiments are merely specific forms of the invention described in the summary section of the invention, and do not limit the elements of the invention described in the summary section of the invention.

Industrial Applicability

[0046] The invention of the present disclosure can be used in the manufacturing industry of hybrid vehicles and the like.

Explanation of Signs

[0047] 1 Hybrid vehicle, 2 Engine, 20 EGECU (Engine Electronic Control Unit), 3 Power transmission device, 4 High-voltage battery, 5 Low-voltage battery, 6 Power control unit (PCU), 30 TMECU (Transmission Electronic Control Unit), 35 Transmission, 60 MGECU (Motor Electronic Control Unit), 70 HVECU (Hybrid Electronic Control Unit), K0 Clutch.

Claims

1. In a control device for a hybrid vehicle including an engine capable of outputting driving power for traveling, an electric motor capable of outputting driving power for traveling, and a battery that exchanges power with the electric motor, it is determined whether the rotational speed of the engine has become less than a predetermined stall rotational speed, the number of times the determination that the rotational speed has become less than the stall rotational speed is counted, and when the number of times has become equal to or greater than a predetermined threshold value, the hybrid vehicle is caused to perform retreat traveling using only the power from the electric motor, and when the operation stop of the engine is prohibited due to an abnormality of an element related to the start of the engine, the threshold value is made smaller than when the operation stop of the engine is not prohibited due to the abnormality of the element. A control device for a hybrid vehicle.

2. In the control device for a hybrid vehicle according to Claim 1, the electric motor outputs a cranking torque for starting the engine by consuming electric power from the battery in response to a start request of the engine. A control device for a hybrid vehicle.

3. In the control device for a hybrid vehicle according to Claim 1 or 2, the hybrid vehicle includes a transmission connected to the electric motor, and a clutch that connects the engine and the electric motor and disconnects the connection therebetween. A control device for a hybrid vehicle.

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