Control device for vehicle

Abstract

To extend an evacuation travel period in which battery-less travel is executed as evacuation travel.SOLUTION: There is provided a control device for a vehicle including: an engine; a starter for starting up the engine; a motor generator connected to the engine so as to allow power transmission; a high-voltage battery for supplying electric power to the motor generator; a relay provided between the high-voltage battery and the motor generator; and an auxiliary battery for supplying electric power to the starter. When it is determined that battery-less travel is necessary, the control device executes a transition to the battery-less travel during an idling period of the engine. When the transition to the battery-less travel fails, or the battery-less travel is stopped, the control device makes a retry of the transition to the battery-less travel. When the engine is not in an idling state at the time of the retry, the control device waits to make the retry until the engine is put into the idling state.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] Patent Document 1 discloses a control device for a vehicle equipped with a mild hybrid system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-231769 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a vehicle equipped with a mild hybrid system, it is conceivable to perform battery-less driving as an evacuation driving. However, there is a high possibility that battery-less driving will stop due to external disturbances. If battery-less driving stops unintentionally, battery-less driving will be retried, but it is expected that an upper limit will be set for the number of retries from the viewpoint of protecting parts, etc. In this case, if the possibility of stopping battery-less driving due to external disturbances and the possibility of failure in the transition to battery-less driving are not taken into consideration, the number of retries will quickly reach the upper limit, making it impossible to retry, and there is a risk that the evacuation driving period will be shortened.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to provide a vehicle control device that can extend the evacuation traveling period in which battery-less traveling is performed as evacuation traveling. [Means for solving the problem]

[0006] The present invention is a control device for a vehicle including an engine, a starter that starts the engine by cranking, a motor generator connected to the engine via a transmission device so as to transmit power, a high-voltage battery that supplies power to the motor generator, a relay provided between the high-voltage battery and the motor generator, and an auxiliary battery that supplies power to the starter, wherein when it is determined that batteryless driving is necessary in which the relay is turned off and the high-voltage battery is electrically disconnected from the motor generator, the control device performs a transition to the batteryless driving during an idle period of the engine, and if the transition to the batteryless driving cannot be made or the batteryless driving is stopped, the control device retries the transition to the batteryless driving, a predetermined upper limit is set for the number of times the retries are performed, and if the engine is not in an idle state when the retry is requested, the control device waits for the retry until the engine is in an idle state. Effect of the Invention

[0007] In the present invention, the evacuation traveling period during which battery-less traveling is performed as the evacuation traveling can be extended. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating a vehicle according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing a processing sequence and unit states of the batteryless control. [Diagram 3] FIG. 3 is a flow chart showing control before transition to battery-less running. [Figure 4] FIG. 4 is a flow chart showing control during battery-less running. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle control device according to an embodiment of the present invention will be specifically described below. Note that the present invention is not limited to the embodiment described below.

[0010] 1 is a diagram illustrating a vehicle according to an embodiment. The vehicle 1 includes an engine (ENG) 2, a power transmission (T / M) 3, a starter 4, a motor generator (MG) 5, a high-voltage battery 6, a DC-DC converter 7, an auxiliary battery 8, auxiliary equipment 9, an integrated ECU 21, an EFI-ECU 22, and an MG-ECU 23. The control device of the vehicle 1 includes the integrated ECU 21, the EFI-ECU 22, and the MG-ECU 23.

[0011] The vehicle 1 is equipped with an engine 2 and a motor generator 5 as power sources, and is a vehicle equipped with a mild hybrid system.

[0012] The engine 2 is a power source of the vehicle 1. Power output from the engine 2 is transmitted to wheels via a power transmission device 3. The power transmission device 3 includes a gear mechanism such as a transmission, and forms a power transmission path between the engine 2 and the wheels.

[0013] The starter 4 is a starter motor that starts the engine 2 by cranking. The starter 4 is driven by power supplied from an auxiliary battery 8. The shaft of the starter 4 is connected to the crankshaft of the engine 2 so as to be capable of transmitting power. When the starter 4 is driven, the shaft of the starter 4 rotates, thereby rotating the crankshaft of the engine 2, and the engine 2 starts.

[0014] The motor generator 5 functions as an electric motor and a generator. The motor generator 5 is connected to the engine 2 via a transmission device 10 so as to be capable of transmitting power. The transmission device 10 is a belt-type transmission device, and includes a pulley that rotates integrally with the crankshaft of the engine 2, a pulley that rotates integrally with the shaft of the motor generator 5, and a belt wound around these pulleys. The motor generator 5 starts the engine 2 via the transmission device 10. Methods for starting the engine 2 include a method for starting the engine 2 using the starter 4 alone, a method for starting the engine 2 using the motor generator 5 alone, and a method for starting the engine 2 using both the starter 4 and the motor generator 5.

[0015] The motor generator 5 is driven by electric power supplied from a high-voltage battery 6. When the power of the engine 2 is insufficient, the motor generator 5 is driven as an electric motor to supplement the power of the engine 2. When the power of the engine 2 is sufficient, the motor generator 5 is driven as a generator to store electric power in an auxiliary battery 8. The motor generator 5 is electrically connected to a DCDC converter 7. The electric power generated by the motor generator 5 is stored in the high-voltage battery 6.

[0016] The high-voltage battery 6 supplies power to the motor generator 5. The high-voltage battery 6 is composed of a secondary battery such as a lithium-ion battery. The rated voltage of the high-voltage battery 6 is 48 V. The high-voltage battery 6 is electrically connected to the motor generator 5 via an inverter 11. The high-voltage battery 6 is also electrically connected to the inverter 11 and the motor generator 5 via an SMR 12. The high-voltage system is composed of the high-voltage battery 6 and the SMR 12.

[0017] The SMR 12 is a relay provided between the high-voltage battery 6 and the inverter 11. When the SMR 12 is in the ON state, the high-voltage battery 6 and the inverter 11 are electrically connected to each other. When the SMR 12 is in the OFF state, the high-voltage battery 6 and the inverter 11 are cut off so that no current flows between them. The SMR 12 switches between the ON state and the OFF state in response to a command signal from the integrated ECU 21.

[0018] The DCDC converter 7 is a power conversion device provided between the motor generator 5 and the auxiliary battery 8. The DCDC converter 7 is electrically connected between the high-voltage power line and the low-voltage line. The DCDC converter 7 steps down the voltage of the high-voltage power line and supplies it to the low-voltage line. The DCDC converter 7 is electrically connected to the auxiliary battery 8 and the auxiliary 9 via the low-voltage line.

[0019] The auxiliary battery 8 supplies power to the starter 4. The rated voltage of the auxiliary battery 8 is 12 V. The auxiliary battery 8 is electrically connected to the starter 4, the DCDC converter 7, and the auxiliary 9 via a low-voltage line. The auxiliary battery 8 is electrically connected to the inverter 11 via the DCDC converter 7.

[0020] The integrated ECU 21 is an electronic control device that controls the high-voltage system. Signals from various sensors are input to the integrated ECU 21. The integrated ECU 21 executes various controls in response to the signals from the various sensors. The integrated ECU 21 controls the SMR 12 and also controls the DCDC converter 7. The integrated ECU 21 includes an integrated control unit that controls the high-voltage system and a converter control unit that controls the DCDC converter 7.

[0021] The integrated ECU 21 is also connected to the EFI-ECU 22 so as to be able to communicate with the EFI-ECU 22. The integrated ECU 21 and the EFI-ECU 22 are configured so as to be able to transmit and receive information between the ECUs via a CAN or direct wiring. The integrated ECU 21 can recognize the state of the engine 2, such as whether the engine 2 is in an idle state, by communicating with the EFI-ECU 22.

[0022] The EFI-ECU 22 is an electronic control device that controls the engine 2. The EFI-ECU 22 includes an engine control unit. The EFI-ECU 22 controls fuel injection and ignition timing in the engine 2. The EFI-ECU 22 executes starting control of the engine 2. In the engine starting control, when the starter 4 starts the engine 2 alone, the EFI-ECU 22 outputs a command signal to the starter 4 and performs cranking by the starter 4.

[0023] The MG-ECU 23 is an electronic control device that controls the motor generator 5. The MG-ECU 23 includes a motor control unit. The MG-ECU 23 outputs a command signal to the inverter 11 to control the driving of the motor generator 5. The inverter 11 has a plurality of switching elements that perform switching operations in response to the command signal from the MG-ECU 23. The MG-ECU 23 is connected to the integrated ECU 21 so as to be able to communicate with each other. The MG-ECU 23 and the integrated ECU 21 are configured so that information can be transmitted and received between the ECUs via a CAN or a direct line.

[0024] The vehicle 1 configured as above can perform batteryless running. Batteryless running is an evacuation running in which the SMR 12 is turned off to electrically disconnect the high voltage battery 6 from the motor generator 5, and the DCDC converter 7 continues to charge the auxiliary battery 8 with the generated energy of the motor generator 5, thereby preventing engine stall. When batteryless running fails, the power of the auxiliary battery 8 is used as a power source, and 48V is generated by boosting it with the DCDC converter 7, and batteryless running is performed again using the motor generator 5. Here, from the viewpoint of protecting the auxiliary 9, the viewpoint of protecting the boost circuit of the DCDC converter 7, and the deterioration of the reliability of the high voltage system, a limit is set on the number of retries to transition to batteryless running. Batteryless running is easily affected by disturbances, and control failure and retries are repeated. Therefore, if retries are performed indiscriminately, the upper limit number of times will be reached. Therefore, the control device of the vehicle 1 is configured to refrain from retrying in situations where a control failure of battery-less driving is expected, to cover power using only the energy of the auxiliary battery 8, and to continue battery-less driving by performing a retry in situations where a control failure does not occur.

[0025] Batteryless is a failure mode in which an abnormality occurs in the high-voltage battery 6. This failure mode includes one-pole welding of the SMR 12, loss of communication with the sub-microcomputer, and failure of the sub-microcomputer. The function lost by the batteryless is the function to grasp the state of the high-voltage battery 6. Batteryless control includes control to shut off the SMR 12. When the engine 2 is stopped, it is started by the starter 4, and power is generated by keeping the voltage of the motor generator 5 constant. The power generated by the motor generator 5 is consumed by the output of the DCDC converter 7. The characteristic of batteryless control is to balance the output of the motor generator 5 and the power consumption of the DCDC converter 7. In batteryless control, the SMR 12 is shut off, so if the balance does not match and the motor generator 5 becomes overvoltage, batteryless driving is terminated.

[0026] 2 is a diagram showing the processing sequence and unit states of the batteryless control. The processing sequence is performed in the order of battery cutoff, engine start, motor start, power generation maintenance, failure to maintain power generation, batteryless running retry, and return to power generation maintenance.

[0027] In the battery cutoff, the SMR 12 switches from the on state to the off state, and the high-voltage battery 6 is electrically disconnected. The electrically disconnected state of the high-voltage battery 6 is maintained in the processing sequence after the battery cutoff. In the engine start, cranking is performed by the starter 4. In the motor start, the power boosted by the boost operation of the DCDC converter 7 is supplied from the DCDC converter 7 to the motor generator 5, and the motor generator 5 is started. When the motor generator 5 is started, it functions as a generator. In the power generation maintenance, the motor generator 5 is maintained in a state of functioning as a generator, and the power generated by the motor generator 5 is stepped down by the DCDC converter 7 to charge the auxiliary battery 8. In the power generation maintenance failure, the power generation by the motor generator 5 ends, and each switching element of the DCDC converter 7 is in a neutral state. In the batteryless running retry, the DCDC converter 7 is operated to boost the power generation by the motor generator 5. When the motor generator 5 enters a power generating state, each switching element of the DC-DC converter 7 enters a neutral state, and the processing sequence shifts from the battery-less running retry to the power generation maintenance.

[0028] 3 is a flow chart showing control before transition to batteryless running. The control shown in FIG. 3 is control in a state before transition to batteryless running, and is executed by the integrated ECU 21.

[0029] The integrated ECU 21 determines whether or not a transition to battery-less running is necessary (step S1). In step S1, it is determined whether or not an abnormality has occurred in the high-voltage battery 6. The integrated ECU 21 determines whether or not the above-mentioned failure mode has occurred. In step S1, the integrated ECU 21 determines whether or not battery-less running (evacuation running) is necessary, in which the vehicle 1 runs with the SMR 12 in the off state and the high-voltage battery 6 electrically disconnected from the motor generator 5.

[0030] If it is determined that transition to battery-less running is not necessary (step S1: No), this control routine proceeds to step S6.

[0031] When it is determined that a transition to battery-less running is necessary (step S1: Yes), the integrated ECU 21 determines whether the engine 2 is idling or not (step S2). The integrated ECU 21 determines whether the engine 2 is in an idling state or not based on information received from the EFI-ECU 22.

[0032] If it is determined that the engine 2 is idling (step S2: Yes), the integrated ECU 21 transitions to batteryless running (step S3). In step S3, the transition to batteryless running is performed while the engine 2 is idling. If the transition to batteryless running cannot be performed or if batteryless running is stopped, the integrated ECU 21 retries the transition to batteryless running in step S3. After performing the process of step S3, this control routine proceeds to step S6.

[0033] If it is determined that the engine 2 is not idling (step S2: No), the integrated ECU 21 determines whether the auxiliary voltage is low (step S4). In step S4, it is determined whether the voltage of the auxiliary battery 8 is low compared to the rated voltage. In step S4, the integrated ECU 21 determines whether the voltage of the auxiliary battery 8 is lower than 11 V, for example.

[0034] If it is determined that the auxiliary voltage is low (step S4: Yes), this control routine proceeds to step S3. When the voltage of the auxiliary battery 8 is lower than the rated voltage, the control routine proceeds to step S3 where the transition to batteryless running is retried with priority given to the possibility of generating power, since it is acceptable for the retry to fail. Since batteryless running is a fail-safe for charging the auxiliary battery 8, it is desirable to retry the transition to batteryless running when the voltage of the auxiliary battery 8 is low.

[0035] If it is determined that the auxiliary voltage has not decreased (step S4: No), the integrated ECU 21 waits for a transition to batteryless running (step S5). In step S5, the transition to batteryless running is waited for until the engine 2 is in an idle state. After the process of step S5 is performed, this control routine proceeds to step S6.

[0036] Then, the integrated ECU 21 determines whether the number of retries to transition to batteryless running is less than the upper limit (step S6). In step S6, it is determined whether the number of retries to transition to batteryless running is less than the upper limit. A predetermined upper limit is set for the number of retries. The upper limit is a number that is set in advance. For example, the upper limit is set to 10 times. In step S6, the integrated ECU 21 determines whether the number of retries is less than 10 times.

[0037] If it is determined that the number of retries to transition to battery-less running is less than the upper limit (step S6: Yes), this control routine ends.

[0038] If it is determined that the number of retries to transition to battery-less running is equal to or greater than the upper limit (step S6: No), the integrated ECU 21 terminates the high voltage system (step S7). In step S7, power generation by the motor generator 5 is stopped, and charging of the auxiliary battery 8 with the power generated by the motor generator 5 is terminated. After the processing of step S7 is performed, this control routine ends.

[0039] 4 is a flow chart showing control during battery-less running. The control shown in FIG. 4 is control that is started during battery-less running and is executed by the integrated ECU 21.

[0040] The integrated ECU 21 determines whether or not it is necessary to retry transition to batteryless running (step S11). In step S11, it is determined whether or not batteryless running has been stopped due to a control failure.

[0041] If it is determined that there is no need to retry transition to battery-less running (step S11: No), this control routine proceeds to step S16.

[0042] When it is determined that the transition to battery-less running needs to be retried (step S11: Yes), the integrated ECU 21 determines whether the engine 2 is idling (step S12). The process of step S12 is the same as the process of step S2 shown in FIG.

[0043] If it is determined that the engine 2 is idling (step S12: Yes), the integrated ECU 21 retries transition to batteryless running (step S13). In step S13, as a retry of transition to batteryless running, the DC-DC converter 7 is caused to perform a boost operation to attempt power generation by the motor generator 5. After the process of step S13 is performed, this control routine proceeds to step S16.

[0044] If it is determined that the engine 2 is not idling (step S12: No), the integrated ECU 21 determines whether the auxiliary voltage is low (step S14). The process of step S14 is similar to the process of step S4 shown in FIG.

[0045] If it is determined that the auxiliary voltage is decreased (step S14: Yes), this control routine proceeds to step S13. A positive determination in step S14 has the same meaning as a positive determination in step S4.

[0046] If it is determined that the auxiliary voltage has not decreased (step S14: No), the integrated ECU 21 waits for a retry of transition to batteryless running (step S15). In step S15, if the engine 2 is not in an idle state when the retry is requested, the retry of transition to batteryless running is waited for until the engine 2 is in an idle state. After the process of step S15 is performed, this control routine proceeds to step S16.

[0047] Then, the integrated ECU 21 determines whether or not the number of retries for transitioning to the batteryless running is less than the upper limit number (step S16). The process of step S16 is similar to the process of step S6 shown in FIG.

[0048] If it is determined that the number of retries to transition to battery-less running is less than the upper limit (step S16: Yes), this control routine ends.

[0049] If it is determined that the number of retries to transition to battery-less running is equal to or greater than the upper limit (step S16: No), the integrated ECU 21 terminates the high-voltage system (step S17). The process of step S17 is the same as the process of step S7 shown in Fig. 3. After the process of step S17 is performed, this control routine ends.

[0050] As described above, according to the embodiment, in a scene where a failure of the batteryless control is expected, retrying the transition to batteryless running is postponed, and power is supplied only from the energy of the auxiliary battery 8, and in a scene where the batteryless running control does not fail, the transition to batteryless running is retried, thereby making it possible to sustain batteryless running. This makes it possible to extend the evacuation running period.

[0051] 3 and step S12 shown in FIG 4 are not limited to determining whether the engine 2 is idling, and may be a determination process based on conditions such as the accelerator opening and engine speed. For example, in step S2, it may be determined whether the speed of the engine 2 is within a predetermined speed range. The integrated ECU 21 may determine whether the engine speed is greater than 0 and less than the predetermined speed.

[0052] Moreover, the process of step S4 shown in Fig. 3 and the process of step S14 shown in Fig. 4 are not limited to the process of determining a drop in the auxiliary voltage. For example, when the auxiliary voltage is low, it is acceptable for the retry to fail, so the possibility of generating power may be prioritized, and the condition for transitioning to batteryless running may be branched. This condition branch prioritizes safety. The presence or absence of this condition branch does not directly relate to the extension of the life of the batteryless control. [Explanation of symbols]

[0053] 1 vehicle 2 Engine (ENG) 3 Power transmission device (T / M) 4 Starter 5 Motor generator (MG) 6 High voltage battery 7 DC-DC Converter 8 Auxiliary Battery 9 Auxiliary Equipment 10 Transmission 11 Inverter 12 SMR 21 Integrated ECU 22 EFI-ECU 23 MG-ECU

Claims

[Claim 1] The engine, a starter that starts the engine by cranking; a motor generator connected to the engine via a transmission device so as to be capable of transmitting power; a high-voltage battery that supplies power to the motor generator; a relay provided between the high-voltage battery and the motor generator; an auxiliary battery that supplies power to the starter; A control device for a vehicle comprising: When it is determined that battery-less running is necessary, in which the relay is turned off and the vehicle is run in a state in which the high-voltage battery is electrically disconnected from the motor generator, a transition to the battery-less running is implemented during an idle period of the engine, If the transition to the battery-less running cannot be performed or if the battery-less running is stopped, the transition to the battery-less running is retried; A predetermined upper limit is set for the number of times the retry is performed, If the engine is not idle when the retry is requested, the retry waits until the engine is idle. A vehicle control device comprising:

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