JP5772438B2 - Electric car - Google Patents

Description

  The present invention relates to an electric vehicle. The electric vehicle in this specification includes a fuel cell vehicle and a hybrid vehicle having both a wheel driving motor and an engine.

  Electric vehicles include ordinary engine vehicles such as a high-power motor for driving wheels, a battery (main battery) that stores the power supplied to the motor, and an inverter that converts the DC power of the main battery into AC power suitable for motor driving. Many electrical devices that handle large currents. For this reason, various measures specific to electric vehicles that are not necessary for conventional engine vehicles are taken. For example, in Patent Document 1, in a hybrid vehicle, when an engine stop signal is input to the control device during traveling, the engine is forcibly stopped, so that a large current flows through the motor, and the amount of discharge of the main battery is A technique for preventing the battery life from being lowered as a result of exceeding the upper limit is disclosed.

JP 2007-216833 A

  One of the countermeasures specific to electric vehicles is a countermeasure when the driver accidentally turns off the main switch of the vehicle while traveling. Here, the main switch of the vehicle is a switch provided in the driver's seat, generally called an “ignition switch”. In the case of an electric vehicle, the main switch is an ON system and is an electric system composed of an inverter and a motor. The relay connecting the high-output main battery is closed (the electric system and the main battery are connected), and the relay is opened in the OFF state. When the main switch is turned off, the electric circuit of the control system is turned off. On the other hand, since the motor continues to rotate by inertia, a counter electromotive force is generated. Since the electric circuit is turned off, the circuit for appropriately processing the counter electromotive force does not operate, and there is a possibility that some device may be damaged by the neglected counter electromotive force. In addition, “when the main switch is turned off” means, in other words, a case where the drive system (wheel drive motor or wheel drive motor and engine) is stopped by a switch operation in the driver's seat. Is equivalent.

  One such device is an electric pump of a cooling device that cools an inverter (an inverter that supplies AC power to a wheel driving motor), and an electric pump for circulating a refrigerant. Conventionally, when the main switch of the vehicle is turned off, the power supply to the electric pump is immediately stopped. However, if the electric pump is immediately stopped when the main switch is turned off while the vehicle is running, the electric pump may be damaged for the following reason. Since the inverter operates to generate heat during traveling, the electric pump discharges a refrigerant having a corresponding flow rate. When the electric pump is stopped in this state (when power supply to the electric pump is stopped), the electric pump is reversely driven from the output shaft side by the inertial force of the refrigerant flow, and a back electromotive force is generated in the electric pump. If the magnitude of the back electromotive force exceeds the allowable value of the electric pump, the electric pump is damaged. This specification provides a technique for protecting an electric pump of an inverter cooling device when a main switch of a vehicle is accidentally turned off during traveling.

  An electric vehicle disclosed in this specification includes an inverter that supplies electric power to a motor, an electric pump that circulates a refrigerant that cools the inverter, and a controller that controls the electric pump. If the vehicle speed is not zero when the main switch of the vehicle provided in the driver's seat is turned off, the controller continues to operate the electric pump until the vehicle speed becomes zero. Note that “until the vehicle speed reaches zero” only needs to be substantially zero, and a slight vehicle speed (for example, less than 1.0 km / h) may be regarded as zero. Further, the controller is supplied with power from the battery while the vehicle speed is not zero even when the main switch is turned off.

  In the electric vehicle disclosed in this specification, when the vehicle speed is not zero, the electric pump for cooling the inverter is not immediately stopped (the power supply is not stopped) even if the main switch of the vehicle is turned off. Continue driving until zero. Since the electric pump continues to rotate by itself, no back electromotive force is generated or only a small amount is generated. This electric vehicle prevents the electric pump from being damaged when the main switch of the vehicle is accidentally turned off during traveling. As described above, the technology disclosed in this specification can also be applied to a fuel cell vehicle or a hybrid vehicle including a vehicle driving motor and an engine.

  If the vehicle speed is not zero when the main switch of the vehicle is turned off during traveling, it is only necessary to avoid damage caused by the counter electromotive force. Therefore, it is not necessary to continue operating the electric pump at the same rotational speed as before. If the vehicle speed is not zero when the main switch is turned off, the controller may change the rotational speed of the pump to a lower rotational speed (and a non-zero rotational speed) than immediately before the main switch is turned off. Is preferred. Or it is also suitable for a controller to reduce the rotation speed of a pump gradually to a predetermined rotation speed lower limit. In any case, the electric pump is not unnecessarily rotated at a high speed.

If the driver notices after the main switch of the vehicle is temporarily turned off during traveling, it may be turned on again. In preparation for such a case, if the vehicle speed is not zero when the main switch is turned off and the main switch is turned on again while continuing the operation of the electric pump after the main switch is turned off Return to the pump control before the main switch is turned off .

It is a block diagram of the cooling device of a hybrid vehicle. It is a flowchart of the process which a controller performs. It is a flowchart of the process which the controller of 2nd Example performs.

  (First Embodiment) FIG. 1 is a block diagram of a cooling apparatus 100 for a hybrid vehicle according to an embodiment. The cooling device 100 is mounted on a hybrid vehicle including a wheel driving motor 18 and an engine 14. The motor 18 is disposed in a case of the drive train 15 together with a power distributor (not shown). The power distributor is a gear set that distributes / combines the output of the motor 18 and the output of the engine 14 and transmits them to the axle. The inverter 7 converts DC power of a battery (not shown) into AC power and supplies it to the motor 18. The inverter 7 also has a function of converting regenerative power (AC power) generated by the motor 18 during braking into DC power suitable for charging the battery.

  The cooling device 100 cools the inverter 7 and the motor 18. The cooling device 100 cools the inverter 7 and the motor 18 by circulating the refrigerant in the refrigerant flow path 2 that goes around the inverter 7, the motor 18 (oil cooler 9), the reserve tank 8, and the radiator 6. Strictly speaking, in the hybrid vehicle of this embodiment, the refrigerant of the cooling device 100 does not directly cool the motor 18. The drive train 15 incorporating the motor 18 is provided with a unique refrigerant flow path 16 and a pump 17 using oil as a refrigerant. The refrigerant of the cooling device 100 takes the heat of the oil by the oil cooler 9. The cooled oil cools the motor 18. That is, the refrigerant of the cooling device 100 indirectly cools the motor 18 via another refrigerant (oil). The refrigerant is, for example, LLC. LLC (Long Life Coolant) is a refrigerant commonly referred to as a radiator liquid, and is an antifreeze liquid such as ethylene glycol.

  The radiator 6 cools the refrigerant by the air received while the vehicle is traveling. The reserve tank 8 is a tank that temporarily stores the refrigerant circulating in the refrigerant flow path 2. In addition to the above, the refrigerant flow path 2 is provided with a pump 10 for circulating the refrigerant. The pump 10 is an electric pump that operates on battery power. The pump 10 is provided with a rotation speed sensor 4 for measuring the rotation speed. Further, a temperature sensor 3 that measures the temperature of the refrigerant flowing through the refrigerant flow path 2 is provided in the vicinity of the pump 10.

The pump 10 is controlled by the controller 12. Usually, the controller 12 controls the pump 10 according to the temperature of the refrigerant measured by the temperature sensor 3. The controller 12 drives the pump 10 in a stronger operation mode (high refrigerant discharge capability) as the refrigerant temperature is higher. In this embodiment, the operation mode of the pump 10 is divided into the following five stages. The operation mode becomes stronger in the order of (5) to (1) (the refrigerant discharge capacity becomes higher).
(1) Super Hi
(2) Hi
(3) Mid
(4) Lo
(5) Super Lo

  The controller 12 receives a signal indicating that the main switch 26 of the vehicle has been turned off from the HV controller 24 which is a host controller. The HV controller 24 is based on information such as vehicle speed, refrigerant temperature, battery state of charge (SOC: State Of Charge), and the like. Value) and the state of the main switch 26 is transmitted.

The main switch 26 is a so-called ignition switch provided in the driver's seat. The main switch 26 is a rotary type and can take the following four stages.
(1) OFF: The vehicle system is in a completely stopped state (however, power is supplied to devices that require constant energization, such as watches and security systems).
(2) ACC-ON (Ready-OFF): so-called accessory-on, in which power is supplied to audio, headlights, air conditioners, etc. (however, if these devices are switched off, Device does not work). Note that a relay (system main relay) that connects the main battery to the inverter remains open, and no electric power is supplied to the traveling drive system.
(3) Ready-ON: a state where the system main relay is closed (a state where the main battery and the electric system of the travel drive system are connected). In this state, electric power is supplied to the inverter (however, electric power is not supplied to the motor unless the switching element in the inverter operates).
(4) Cell-Start: This is a so-called cell start state, where the cell motor is driven to rotate the engine. When the driver releases his hand in the Cell-Start state, the main switch 26 returns to the Read-ON state due to the reaction force of the spring.

  If the accelerator is depressed when the main switch 26 is in the “Ready-ON” state, the controller 12 drives the motor 18 and / or the engine 14 according to the accelerator opening. While the motor 18 and / or the engine 14 is being driven, the controller 12 controls the pump 10 according to the refrigerant temperature as described above.

  When the controller 12 receives from the host HV controller 24 a signal indicating that the main switch 26 has been turned off, the controller 12 executes the processing of the flowchart shown in FIG. Here, “the main switch 26 has been turned off” means that, in the four-stage switch state described above, from (3) Ready-On to (1) OFF or (2) ACC-ON ( It means that it has switched to (Ready-OFF).

  Processing executed by the controller 12 will be described along the flowchart of FIG. When receiving a signal indicating that the main switch 26 is turned off from the HV controller 24, the controller 12 checks whether or not the vehicle speed is zero (S2). A signal from the vehicle speed sensor 22 is sent to the controller 12 (see FIG. 1). When the vehicle speed is zero (S2: YES), that is, when the vehicle is stopped, the controller 12 immediately stops the pump 10 (S7). Here, stopping the pump 10 means stopping the power supply to the pump 10.

  If the vehicle speed is not zero when the signal indicating the main switch OFF is received (S2: NO), the controller 12 lowers the operation mode of the pump 10 from the previous operation mode (S3). For example, when the operation mode when the main switch 26 is turned off is “Super Hi”, the controller 12 changes the operation mode to “Hi” in Step S3. For example, when the operation mode when the main switch 26 is turned off is “Mid”, the controller 12 changes the operation mode to “Lo” in step S3. If the operation mode immediately before the main switch 26 is turned off is “Super Lo”, there is no further weak operation mode. In that case, the controller 12 maintains the operation mode as “Super Lo”. . That is, the controller 12 can set the pump 10 to any one of a plurality of operation modes having different refrigerant discharge forces. If the vehicle speed is not zero when the main switch 26 is turned off, the operation mode is decreased by one step. . However, if the operation mode when the vehicle speed is not zero when the main switch 26 is turned off is the lowest operation mode, the operation mode is maintained.

  After the operation mode of the pump 10 is lowered by one step, the controller 12 monitors whether or not a signal indicating that the main switch 26 is turned on again is received until the vehicle speed becomes zero (S4, S5: NO). ). A signal indicating that the main switch 26 is turned on again is also sent from the HV controller 24. When the controller 12 receives a signal indicating that the main switch 26 is turned on again before the vehicle speed becomes zero, the controller 12 returns to the normal pump control mode (S4: YES, S6). In other words, the controller 12 returns to the pump operation mode when the main switch is turned off.

  On the other hand, when the vehicle speed becomes zero without the main switch 26 being turned ON again (S5: YES), the controller 12 stops the pump 10 (stops the power supply to the pump 10) and ends the process. (S7).

  As described above, the hybrid vehicle of the first embodiment immediately stops the pump 10 if the vehicle speed is zero when the main switch 26 is turned OFF, and continues the operation of the pump 10 otherwise. By providing such a process, when the main switch 26 is accidentally turned OFF during traveling, the pump 10 is reversely driven by the inertial force of the refrigerant, thereby preventing the pump 10 from being damaged. .

  (Second Embodiment) Next, an electric vehicle according to a second embodiment will be described. The hardware configuration of the electric vehicle of the second embodiment is the same as that of the electric vehicle (hybrid vehicle) of the first embodiment. Accordingly, in the following description, the reference numerals in FIG. 1 are used to indicate the hardware configuration. The electric vehicle of the second embodiment is different from the first embodiment in the process executed by the controller 12. FIG. 3 shows a flowchart of processing executed by the controller 12 of the hybrid vehicle of the second embodiment.

  When receiving a signal indicating that the main switch 26 is turned off from the HV controller 24, the controller 12 checks whether or not the vehicle speed is zero (S12). When the vehicle speed is zero (S12: YES), that is, when the vehicle is stopped, the controller 12 immediately stops the pump 10 (S18). When the vehicle speed is not zero when the signal indicating the main switch OFF is received (S12: NO), the controller 12 checks whether or not the rotation speed of the pump 10 is a predetermined lower limit rotation speed (S13). . When the rotation speed of the pump 10 exceeds the predetermined lower limit rotation speed (S13: NO), the controller 12 decreases the rotation speed of the pump 10 by a predetermined rotation speed (S14). An example of the lower limit rotational speed is the rotational speed of the lowest operation mode (super Lo) in the first embodiment. Further, the predetermined rotation speed is, for example, 100 [rpm]. On the other hand, when the rotation speed of the pump 10 is a predetermined lower limit rotation speed (S13: YES), the controller 12 skips step S14 and proceeds to step S15.

  While the vehicle speed is not zero (S16: NO), the controller 12 repeats the processes of steps S13 and S14 described above. That is, while the vehicle speed is not zero (S16: NO), the controller 12 decreases the rotation speed of the pump 10 by a predetermined rotation speed until the lower limit rotation speed is reached. When the controller 12 receives a signal indicating that the main switch 26 is turned on again while the vehicle speed is not zero, the controller 12 returns to the normal pump control mode (S15: YES, S17). In other words, the controller 12 returns to the pump operation mode when the main switch is turned off.

  When the vehicle speed becomes zero, that is, when the vehicle stops, the controller 12 stops the operation of the pump 10 (S16: YES, Y18).

  The hybrid vehicle of the second embodiment immediately stops the pump 10 if the vehicle speed is zero when the main switch 26 is turned off, and continues the operation of the pump 10 otherwise. While the vehicle speed is not zero, the controller 12 gradually decreases the rotational speed of the pump 10 to the lower limit rotational speed. By providing such processing, the pump 10 is prevented from being damaged when the main switch 26 is mistakenly turned off during traveling, and the pump 10 is not unnecessarily maintained at high speed.

  Points to note regarding the technology of the embodiment will be described. The electric vehicle of the example continued to drive the pump unless the vehicle speed was zero when the main switch was turned off. “Vehicle speed is zero” may be any vehicle speed that is substantially zero. For example, the electric vehicle according to the embodiment may determine that “the vehicle speed is zero” when the vehicle speed is less than 5 km / h.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: Refrigerant flow path 3: Temperature sensor 4: Rotational speed sensor 6: Radiator 7: Inverter 8: Reserve tank 9: Oil cooler 10: Pump 12: Controller 14: Engine 15: Drive train 16: Refrigerant flow path 17: Pump 18 : Motor 100: Cooling device

Claims (3)

An electric vehicle equipped with a motor for driving wheels,
An inverter for supplying power to the motor;
An electric pump for circulating a refrigerant for cooling the inverter;
A controller for controlling the electric pump;
With
When the vehicle speed is not zero when the main switch of the vehicle provided in the driver's seat is turned off, the controller continues to operate the electric pump until the vehicle speed becomes zero ,
If the vehicle speed is not zero when the main switch is turned off, and the main switch is turned on again while continuing the operation of the electric pump after the main switch is turned off, before the main switch is turned off An electric vehicle characterized by returning to the pump control.   2. The controller according to claim 1, wherein if the vehicle speed is not zero when the main switch is turned off, the controller changes the rotational speed of the electric pump to a lower rotational speed than the rotational speed immediately before the main switch is turned off. The electric vehicle described in 1.   2. The electric vehicle according to claim 1, wherein the controller gradually decreases the rotational speed of the electric pump when the vehicle speed is not zero when the main switch is turned off.

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