Hybrid vehicle

Abstract

To provide a hybrid vehicle which even when an abnormality occurs in a motor, accommodates load requirement while performing retreat running.SOLUTION: A hybrid vehicle is provided with: an engine; an automatic transmission which has an input shaft to which power transmitted from the engine through a rotary shaft is input and an output shaft connected to a driving wheel; a motor connected to the rotary shaft; a battery; a relay through which the battery is connected to and disconnected from an electric power line; an inverter which is connected to the electric power line, converts electric power supplied to the electric power line and supplies the converted electric power to the motor and can supply back electromotive force of the motor to the electric power line; a load circuit connected to the electric power line; and a control device which when an abnormality occurs in the motor, controls the engine and the relay in such a manner that the relay is disconnected and the hybrid vehicle performs retreat running with power from the engine and sets rotation speed, which is higher when the load circuit requires loads than when the circuit does not require loads to a target value of rotation speed of the input shaft and controls the transmission.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, hybrid vehicles of this type have been proposed that include an engine, an automatic transmission in which an input shaft is connected to a rotating shaft connected to the output shaft of the engine via a torque converter and the output shaft is connected to drive wheels, a motor generator in which a rotor is connected to the rotating shaft, a battery, and a power control circuit (PCU) that converts the battery's power and supplies it to the motor generator (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-128280 Summary of the Invention [Problem to be solved by the invention]

[0004] In such hybrid vehicles equipped with an engine and a motor, the battery is typically connected to a power line via a relay, and the motor is driven by power supplied to the power line. If an abnormality occurs in the motor, the relay can be shut off, allowing the vehicle to run for evacuation using power from the engine. However, in hybrid vehicles equipped with a load circuit connected to the power line, if an abnormality occurs in the motor and the relay is shut off, only the back electromotive force of the motor is supplied to the power line, which may result in insufficient power being supplied to the load circuit.

[0005] The hybrid vehicle disclosed herein has the primary objective of being able to perform evacuation driving while also responding to the load demands of the load circuit connected to the power line, even if an abnormality occurs in the motor driven by an inverter connected to the battery via a power line. [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 summarized as comprising an engine, an input shaft to which power transmitted from the engine via a rotating shaft is input, and an output shaft connected to drive wheels, an automatic transmission that changes the speed of the power input to the input shaft and outputs it to the output shaft, a motor connected to the rotating shaft, a battery, a relay that connects and disconnects the battery to a power line, an inverter connected to the power line that converts the power supplied to the power line and supplies it to the motor, and is also capable of supplying the motor's back electromotive force to the power line, a load circuit connected to the power line, and a control device that, when an abnormality occurs in the motor, controls the engine and the relay to disconnect the relay and perform evacuation driving using power from the engine, and controls the transmission by setting a higher rotation speed target value for the input shaft when there is a load request from the load circuit compared to when there is no load request.

[0008] In the hybrid vehicle disclosed herein, if an abnormality occurs in the motor, the relay is shut off and the engine is controlled to perform evacuation running using power from the engine. When a load request is received from the load circuit, the transmission is controlled by setting a higher rotational speed target value for the input shaft than when there is no load request. This allows the motor to rotate at a relatively high rotational speed when there is a load request, generating sufficient back electromotive force in the motor to supply the necessary power to the load circuit. As a result, even if an abnormality occurs in the motor, evacuation running can be performed while also responding to the load request. Furthermore, the engine's power performance can be improved as a secondary benefit. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a hybrid vehicle according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram of a high-voltage system including a motor. [Figure 3] 10 is a flowchart illustrating an example of a control process when a motor abnormality occurs. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic diagram of a hybrid vehicle 20 according to this embodiment, and Fig. 2 is a schematic diagram of a high-voltage system including a motor 30. As shown in Fig. 1, the hybrid vehicle 20 according to this embodiment includes an engine 22, a motor 30, an inverter 32, a clutch K0, a power transmission device 40, a high-voltage battery 50, a low-voltage battery 55, and a main electronic control unit (hereinafter referred to as "main ECU") 70.

[0011] The engine 22 is configured as an internal combustion engine that outputs power using hydrocarbon fuel such as gasoline or diesel. A transmission shaft 35 is connected to a crankshaft 23 of the engine 22 via a clutch K0. The clutch K0 is, for example, a hydraulically driven friction clutch, and connects and disconnects the engine 22 and the transmission shaft 35. A starter motor 24 for cranking the engine 22 and an alternator 25 for generating electricity using power from the engine 22 are also connected to the crankshaft 23 of the engine 22.

[0012] The operation of the engine 22 is controlled by an engine electronic control unit (hereinafter referred to as engine ECU) 26. The engine ECU 26 communicates with the main ECU 70, and transmits data relating to the state of the engine 22 to the main ECU 70 and receives control signals from the main ECU 70 as necessary.

[0013] The motor 30 is configured as, for example, a synchronous generator motor having a rotor to which a permanent magnet is attached and a stator around which a three-phase coil is wound. The rotor of the motor 30 is attached to a transmission shaft 35. As shown in FIG. 2, the inverter 32 is connected to a high-voltage battery 50 via a high-voltage power line 51. The inverter 32 has a plurality of (six) transistors T as switching elements and a plurality of (six) diodes D connected in anti-parallel to each transistor T. The motor 30 is rotationally driven by the switching of each transistor T. The motor 30 is also a generator motor, and the power generated by the motor 30 is rectified by the diodes D and supplied to the high-voltage power line 51.

[0014] The power transmission device 40 includes a torque converter 41 and an automatic transmission 44. The torque converter 41 is configured as a typical fluid transmission device with a lock-up clutch. The torque converter 41 is connected to the crankshaft 23 of the engine 22 via a clutch KO and is connected to the rotor of the motor 30. The torque converter 41 amplifies the torque of a transmission shaft 35 connected to an input shaft 42 of the automatic transmission 44, or transmits the torque directly without amplifying it. The automatic transmission 44 is connected to the input shaft 42 and an output shaft 43. The output shaft 43 is connected to a drive shaft 47 that is connected to rear wheels 49a, 49b via a rear differential gear 48. The automatic transmission 44 has multiple planetary gears and multiple hydraulically driven friction engagement elements (clutches, brakes). The automatic transmission 44 transmits power between the input shaft 42 and the output shaft 43 by engaging and disengaging the multiple friction engagement elements to form forward gears (e.g., first through sixth gears) and reverse gears.

[0015] The high-voltage battery 50 is, for example, a lithium-ion battery or a nickel-metal hydride battery having a rated voltage of 48 V, and is connected to a high-voltage power line 51 that is connected to the inverter 32. A system main relay 52 is attached to the high-voltage power line 51, and the high-voltage battery 50 can be disconnected by turning off the system main relay 52. ​​The high-voltage power line 51 is also equipped with high-voltage load circuits, such as an inverter 61 that drives a compressor 62 of an air conditioner 60 that conditions the passenger compartment 21, a DC / DC converter 54 that steps down the power of the high-voltage power line 51 and supplies it to a low-voltage power line 56, and an inverter (not shown) that supplies AC power (AC power of up to 1500 W or 2400 W) to an electrical load connected to an AC outlet equipped in the vehicle. A smoothing capacitor 53 is also attached to the high-voltage power line 51.

[0016] As shown in Fig. 1, the air conditioner 60 includes a refrigeration cycle consisting of a compressor 62, a condenser 63, an expansion valve 64, and an evaporator 65, a blower 66 that blows air cooled by heat exchange with the evaporator 65 of the refrigeration cycle to the outlet 21a of the passenger compartment 21, and an air conditioner electronic control unit (hereinafter referred to as air conditioner ECU) 68. The compressor 62 is driven by an inverter 61 connected to the high-voltage power line 51. As shown in Fig. 2, the inverter 61 has multiple transistors T similar to those of the inverter 32. The compressor 62 is driven to rotate by switching on and off the transistors T of the inverter 61. The air conditioning ECU 68 receives inputs such as a switch signal from an on / off switch 67a attached to an operation panel 67 for turning the air conditioning on and off, a set temperature T* from a set temperature switch 67b also attached to the operation panel 67 for setting the temperature inside the passenger compartment 21, and an occupant room temperature Tin from a temperature sensor 67c attached to the operation panel 67 for detecting the temperature inside the passenger compartment 21. The air conditioning ECU 68 also outputs drive signals to the compressor 62 and the blower 66. Based on the input signals, the air conditioning ECU 68 controls the drive of the compressor 62, the blower 66, etc. so that the occupant room temperature Tin becomes the set temperature T*.

[0017] The low-voltage battery 55 is a lead-acid battery having a rated voltage lower than that of the high-voltage battery 50, for example, a rated voltage of 12V, and is connected to a low-voltage power line 56 that is connected to the starter motor 24 and alternator 25.

[0018] DC / DC converter 54 is connected to high-voltage power line 51 and low-voltage power line 56. DC / DC converter 54 steps down the power on high-voltage power line 51 and supplies it to low-voltage power line 56, and steps up the power on low-voltage power line 56 and supplies it to high-voltage power line 51. DC / DC converter 54 normally steps down the power on high-voltage power line 51 and supplies it to low-voltage power line 56.

[0019] The main ECU 70 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. The main ECU 70 receives signals from various sensors via the input ports. For example, the main ECU 70 receives signals related to the status of the motor 30, the high-voltage battery 50, the low-voltage battery 55, and the powertrain 40. These signals include, for example, the rotational position θm of the motor 30 received from a rotational position sensor 30a attached to the rotor of the motor 30, the phase currents Iv and Iw of the motor 30 received from current sensors 30b attached to the respective phase coils of the motor 30, the coil temperature tm of the motor 30 received from a temperature sensor 30c attached to the stator of the motor 30, the current Ib of the high-voltage battery 50 received from a current sensor 50a attached to the output terminal of the high-voltage battery 50, the rotational speed Nin of the input shaft 42 of the automatic transmission 44 received from a rotational speed sensor 42a attached to the input shaft 42, and the rotational speed Nout of the output shaft 43 of the automatic transmission 44 received from a rotational speed sensor 43a attached to the output shaft 43 of the automatic transmission 44. The main ECU 70 calculates the rotation speed Nm of the motor 30 based on the rotation position θm of the motor 30, and calculates the charge storage percentage SOC, which is the ratio of the remaining capacity to the total capacity of the high-voltage battery 50, based on the integrated value of the current Ib of the high-voltage battery 50. The main ECU 70 also receives as input an ignition signal IG from an ignition switch 80, a shift position SP, which is the operating position of a shift lever 81, from a shift position sensor 82, an accelerator pedal position AP, which is the depression amount of an accelerator pedal 83, from an accelerator pedal position sensor 84, a brake pedal position BP, which is the depression amount of a brake pedal 85, from a brake pedal position sensor 86, and a vehicle speed V from a vehicle speed sensor 87.

[0020] The main ECU 70 outputs various control signals via an output port. For example, the main ECU 70 outputs control signals to the system main relay 52, the inverter 32, the clutch K0, and the automatic transmission 44. The main ECU 70 also communicates with the engine ECU 26 and the air conditioning ECU 68, exchanging control signals and data with them.

[0021] The operation of the hybrid vehicle 20 of this embodiment configured as described above will be described. The main ECU 70 sets the required torque Td* for driving based on the accelerator pedal position AP, the brake pedal position BP, and the vehicle speed V. Next, the main ECU 70 sets the shift points (upshift points, downshift points) of the automatic transmission 44. The main ECU 70 then controls the engine 22, the motor 30, the clutch K0, and the automatic transmission 44 so that the vehicle drives at the required torque Td* while shifting gears at the shift points. Here, the setting of the shift points (upshift points and downshift points) is basically performed based on the accelerator pedal position AP, the vehicle speed V, and the shift map (upshift lines, downshift lines). However, in this embodiment, the setting of the upshift points also takes into consideration the target rotation speed Nin*, which is a target value (limit value) for the rotation speed Nin of the input shaft 42. That is, when the rotation speed Nin of the input shaft 42 reaches an upshift point set based on the rotation speed target value Nin*, the main ECU 70 controls the automatic transmission 44 to perform an upshift in order to reduce the rotation speed Nin of the input shaft 42. This is because, since the rotor of the motor 30 is connected to the input shaft 42 of the automatic transmission 44, depending on the rotation speed Nin of the input shaft 42, there is a risk that a voltage exceeding the withstand voltage will act on the high-voltage power line 51 due to the back electromotive force generated in the motor 30, or that the coils of each phase of the motor 30 will overheat.

[0022] Next, an operation when an abnormality is detected in the motor 30 will be described. Fig. 3 is a flowchart showing an example of a motor abnormality control process executed by the main ECU 70. This process is executed when an abnormality is detected in the motor 30. Examples of abnormalities in the motor 30 include element abnormalities such as overcurrent or overheating in the switching elements of the inverter 32, and sensor abnormalities such as failure of the rotational position sensor 30a or failure of the current sensor 30b. When an abnormality is detected in the motor 30, the gate of the inverter 32 is shut off.

[0023] When the motor abnormality control process is executed, the main ECU 70 (CPU) first turns off the system main relay 52 to disconnect the high-voltage battery 50 from the high-voltage power line 51, and sends a control signal to the engine ECU 26 to drive the vehicle using the power of the engine 22 (evacuation driving), while also controlling the automatic transmission 44 (step S100). Next, the main ECU 70 determines whether a request for power consumption by the high-voltage load circuit has been made (step S102). This determination is made, for example, by determining whether air conditioning by the air conditioner 60 has been requested, whether a request for power supply by the DC / DC converter 54 to the low-voltage power line 56 has been requested, or whether a request for AC power supply to an electrical load connected to an AC outlet has been made. When the main ECU 70 determines that no power consumption is being requested by the high-voltage load circuit, it sets a target rotation speed Nin* of the input shaft 42 of the automatic transmission 44 based on the withstand voltage value of the high-voltage power line 51 and the coil temperature tm of the motor 30 (step S104). The target rotation speed Nin* is set, for example, by setting the smaller of the rotation speed determined by the withstand voltage value of the high-voltage power line 51 or the rotation speed determined by the coil temperature tm of the motor 30. The main ECU 70 then sets the rotation speed obtained by subtracting a predetermined margin from the set target rotation speed Nin* as the upshift point of the automatic transmission 44 (step S108), and ends the motor abnormality control process. As a result, the main ECU 70 controls the automatic transmission 44 so that an upshift is performed when the rotation speed Nin of the input shaft 42 reaches the upshift point.

[0024] On the other hand, when main ECU 70 determines that the high-voltage load circuit is requesting power consumption, it sets a target rotation speed Nin* for input shaft 42 of automatic transmission 44 based on a voltage value obtained by adding the amount of power consumed by the high-voltage load circuit to the withstand voltage value of high-voltage power line 51 and on the coil temperature tm of motor 30 (step S106), and then performs the processing of step S108 to terminate the motor abnormality control processing. Setting of target rotation speed Nin* is performed, for example, by setting the smaller of a rotation speed determined by the voltage value obtained by adding the amount of power consumed by the high-voltage load circuit to the withstand voltage value of high-voltage power line 51 or a rotation speed determined by the coil temperature tm of motor 30. When a power consumption is requested by the high-voltage load circuit, the target rotation speed Nin* is set to a rotation speed that is higher by the amount of power consumed by the high-voltage load circuit, so that the timing of the upshift can be delayed to rotate motor 30 at a relatively high rotation speed. As a result, even if an abnormality occurs in the motor 30 and the gate of the inverter 32 is shut off, the vehicle can be driven to safety using the power of the engine 22, and sufficient power can be supplied to the high-voltage load circuit by the back electromotive force generated by the rotation of the motor 30. Furthermore, since the crankshaft 23 is also connected to the input shaft 42 of the automatic transmission 44 and the engine 22 is also operated at a relatively high rotation speed, the power performance of the engine 22 can also be improved as a secondary effect.

[0025] In the above-described embodiment, the hybrid vehicle 20 is provided with a stepped automatic transmission 44, but it may also be provided with a continuously variable automatic transmission that can continuously change the gear ratio.

[0026] 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]

[0027] The present disclosure is applicable to the hybrid vehicle manufacturing industry and the like. [Explanation of symbols]

[0028] 20 Hybrid vehicle, 22 Engine, 30 Motor, 35 Transmission shaft, 42 Input shaft, 43 Output shaft, 44 Automatic transmission, 50 High voltage battery, 51 High voltage power line, 52 System main relay, 61 Inverter, 70 Main electronic control unit.

Claims

[Claim 1] The engine and an automatic transmission having an input shaft to which power transmitted from an engine via a rotary shaft is input and an output shaft connected to drive wheels, the automatic transmission changing the speed of the power input to the input shaft and outputting the power to the output shaft; a motor connected to the rotary shaft; A battery, a relay for connecting and disconnecting the battery and the power line; an inverter connected to the power line, capable of converting power supplied to the power line and supplying the converted power to the motor, and capable of supplying a back electromotive force of the motor to the power line; a load circuit connected to the power line; a control device that, when an abnormality occurs in the motor, controls the engine and the relay so that the relay is cut off and the vehicle travels by evacuation using power from the engine, and that, when there is a load request from the load circuit, sets a higher rotation speed as a rotation speed target value for the input shaft compared to when there is no load request, and controls the transmission; A hybrid vehicle equipped with

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