Hybrid vehicle control device

Abstract

To provide a control device of a hybrid vehicle that can avoid a situation where an engine cannot be started after the vehicle starts travelling.SOLUTION: A control device of a hybrid vehicle comprises: an engine 2; a high-voltage system that drives a motor generator 3 for driving; and an activation control part 101 that executes an engine start-up determination of determining whether the engine 2 is in a state where start-up of the engine is highly likely to be impossible or not, on the basis of a state of a hybrid vehicle 1, executes HEV activation processing for starting the engine 2 to activate the high-voltage system, when a determined result of the start-up of the engine shows that the engine 2 is in the state where start-up of the engine is highly likely to be impossible, and executes EV activation processing for activating the high-voltage system while stopping the engine 2, when the determined result of the start-up of the engine shows that the engine 2 is not in the state where start-up of the engine is highly likely to be impossible.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 describes a control method for a hybrid vehicle, which includes a step of detecting various state quantities of the vehicle, and a step of starting the system in EV mode, which does not start the engine, if the EV mode prohibition condition is not met.

[0003] In such hybrid vehicles, after the system is started in EV mode and the vehicle starts running, the engine is started when a request to start the engine is made. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-213781 Summary of the Invention [Problem to be solved by the invention]

[0005] However, there is a problem that even if a request to start the engine is made, depending on the state of the hybrid vehicle, the engine may not be able to start.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a control device for a hybrid vehicle that can avoid a situation in which the engine cannot be started after the vehicle has started to travel. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a control device for a hybrid vehicle that includes an engine and a high-voltage system that drives a drive motor generator, and that runs using at least one of the engine and the drive motor generator as a drive source, the control device further including a start-up control unit that executes an initial system start-up process for the hybrid vehicle system, the start-up control unit being configured to determine whether or not the engine is in a state where it is highly likely that it will be unable to start, based on the state of the hybrid vehicle. and a soak time determination for determining whether the soak time is less than a predetermined time. When it is determined that the engine is highly likely to be unable to start as a result of the engine start determination, Or, if it is determined that the soak time is not less than the predetermined time as a result of the soak time determination. executes an HEV start process for starting the engine and activating the high voltage system, and determines as a result of the engine start determination that the engine is not in a state where there is a high possibility that it will become unable to start. and, as a result of the soak time determination, it is determined that the soak time is less than a predetermined time. If this occurs, the EV startup process is executed to start up the high voltage system while the engine is stopped. [Effects of the Invention]

[0008] In this way, according to the present invention, it is possible to avoid a situation in which the engine becomes unable to start after the vehicle has started to move. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram of an inverter for a hybrid vehicle according to an embodiment of the present invention. [Figure 3] FIG. 3 is a flowchart showing the procedure of the initial system startup process of the control device for a hybrid vehicle according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] A control device for a hybrid vehicle according to one embodiment of the present invention is a control device for a hybrid vehicle that has an engine and a high-voltage system that drives a drive motor generator, and that runs using at least one of the engine and the drive motor generator as a drive source, and is equipped with a startup control unit that executes an initial system startup process for the hybrid vehicle system, and the startup control unit is configured to execute an engine start determination that determines whether the engine is in a state where there is a high possibility that it will be unable to start based on the state of the hybrid vehicle, and if the result of the engine start determination determines that there is a high possibility that the engine will be unable to start, execute an HEV startup process that starts the engine and starts the high-voltage system, and if the result of the engine start determination determines that there is not a high possibility that the engine will be unable to start, execute an EV startup process that starts the high-voltage system while keeping the engine stopped.

[0011] As a result, the control device for a hybrid vehicle according to one embodiment of the present invention can avoid a situation in which the engine cannot be started after the vehicle has started to travel. [Example]

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A control device for a hybrid vehicle according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0013] In FIG. 1, a hybrid vehicle 1 according to one embodiment of the present invention includes an engine 2, a drive motor generator 3, a transmission 4, a differential 5, drive wheels 6, and an ECU (Electronic Control Unit) 10.

[0014] The engine 2 is formed with a plurality of cylinders. In this embodiment, the engine 2 is configured so that each cylinder undergoes a series of four strokes, which are an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke.

[0015] An ISG (Integrated Starter Generator) 20 serving as an engine starting device is connected to the engine 2. The ISG 20 is a motor generator connected to the crankshaft of the engine 2 via a belt member such as a belt 21. The ISG 20 functions as an electric motor that rotates when supplied with electric power to drive the engine 2, and also functions as a generator that converts the rotational force input from the crankshaft into electric power.

[0016] A starter motor 22 serving as an engine starting device is connected to the engine 2. A pinion provided at the tip of the rotary shaft of the starter motor 22 meshes with a ring gear attached to the crankshaft of the engine 2, thereby transmitting the driving force of the starter motor 22 to the crankshaft. The starter motor 22 rotates when supplied with electric power, thereby driving the engine 2 to rotate.

[0017] The engine 2 is provided with a water temperature sensor 23. The water temperature sensor 23 detects the temperature of the cooling water of the engine 2 and transmits the detection result to the ECU 10.

[0018] The drive motor generator 3 functions as an electric motor driven by power supplied from a high-voltage battery 31 via an inverter 30, and as a generator that generates electricity using the reverse driving force input from the differential 5.

[0019] Under the control of the ECU 10, the inverter 30 converts DC power supplied from the high-voltage battery 31 into three-phase AC power and supplies it to the drive motor generator 3, and also converts the three-phase AC power generated by the drive motor generator 3 into DC power to charge the high-voltage battery 31. The high-voltage battery 31 is formed of a secondary battery such as a lithium-ion battery.

[0020] As shown in FIG. 2, the inverter 30 includes a smoothing capacitor 32, switching elements 51, 52, 53, 54, 55, and 56, and diodes 57, 58, 59, 60, 61, and 62.

[0021] The smoothing capacitor 32 has an anode connected to the positive electrode of the high-voltage battery 31 and a cathode connected to the negative electrode of the high-voltage battery 31, and is configured to smooth the voltage of the DC power generated between the positive and negative electrodes.

[0022] Each of the switching elements 51, 52, 53, 54, 55, and 56 is controlled by a control signal whose duty ratio is controlled by the ECU 10 so that the direction and amount of current flowing through each of the U, V, and W phases of the drive motor generator 3 becomes alternating current that changes continuously with a phase difference of 120 degrees. As a result, the stator of the drive motor generator 3 forms a rotating magnetic field, causing the rotor of the drive motor generator 3 to rotate.

[0023] Between the inverter 30 and the high-voltage battery 31, there are provided a negative side relay 12 as a main relay, a positive side relay 13 as a main relay, and a circuit in which a pre-charge relay 14 and a pre-charge resistor 15 are connected in series.

[0024] The negative side relay 12 is configured to take either a conductive state in which the negative electrode of the high-voltage battery 31 and the cathode of the smoothing capacitor 32 are electrically connected, or a non-conductive state in which the negative electrode of the high-voltage battery 31 and the cathode of the smoothing capacitor 32 are electrically disconnected, depending on the main relay drive output signal output by the ECU 10.

[0025] For example, the negative relay 12 is controlled by the ECU 10 to be in a conductive state when the drive motor generator 3 is in operation.

[0026] The positive side relay 13 is configured to take either a conductive state in which the positive electrode of the high-voltage battery 31 and the anode of the smoothing capacitor 32 are electrically connected, or a non-conductive state in which the positive electrode of the high-voltage battery 31 and the anode of the smoothing capacitor 32 are electrically disconnected, depending on the main relay drive output signal output by the ECU 10.

[0027] For example, the positive electrode relay 13 is controlled by the ECU 10 to be in a conductive state when the drive motor generator 3 is in operation.

[0028] The precharge relay 14 is configured to take one of two states, a connected state in which the precharge resistor 15 is connected in parallel to the positive side relay 13, and a disconnected state in which the precharge resistor 15 is electrically disconnected from the positive side relay 13, depending on the precharge relay drive output signal output by the ECU 10.

[0029] For example, the precharge relay 14 is controlled by the ECU 10 to be in a connected state before the drive motor generator 3 is activated, and to be in a disconnected state after the positive electrode side relay 13 is in a conductive state.

[0030] In this embodiment, the high-voltage components supplied with power from the high-voltage battery 31 and their associated components are referred to as a high-voltage system. The high-voltage system is configured to include, for example, the drive motor generator 3, the inverter 30, the high-voltage battery 31, the negative-side relay 12, the positive-side relay 13, the pre-charge relay 14, and the pre-charge resistor 15. The high-voltage system may also include an electric water pump for cooling the high-voltage components, an electric vacuum pump for ensuring negative pressure during EV driving using only the driving force of the drive motor generator 3, and the like.

[0031] The high-voltage system may include at least the drive motor generator 3, the inverter 30, the high-voltage battery 31, the negative electrode side relay 12, and the positive electrode side relay 13.

[0032] In Fig. 1, the transmission 4 is configured by a transmission that changes the speed of the rotation output from the engine 2 at a gear ratio corresponding to one of a plurality of gear stages and outputs the changed speed. The output shaft of the transmission 4 is connected to left and right drive wheels 6 via a differential 5. The output shaft of the drive motor generator 3 is connected to the output shaft of the transmission 4.

[0033] The gears that can be established in the transmission 4 include, for example, a driving gear set ranging from a low 1st gear to a high 5th gear, and a reverse gear set. The number of driving gear sets varies depending on the specifications of the hybrid vehicle 1, and is not limited to the above-mentioned 1st gear set to 5th gear set.

[0034] The gear shifting in the transmission 4 is performed by a shift select actuator 42 controlled by the ECU 10.

[0035] The ECU 10 switches the gear position of the transmission 4 according to the operating position of a shift lever 40 operated by the driver. The operating position of the shift lever 40 is selected from, for example, a forward driving range (D range), a motor speed limit range (B range), a reverse driving range (R range), a parking range (N range), and a parking range (P range).

[0036] The operating position of the shift lever 40 is detected by a shift position sensor 41. The shift position sensor 41 is connected to the ECU 10 and transmits the detection result to the ECU 10.

[0037] A clutch 7 is provided in the power transmission path between the engine 2 and the transmission 4. A friction clutch, for example, can be used as the clutch 7. The engine 2 and the transmission 4 are connected via the clutch 7.

[0038] The clutch 7 is operated by a clutch actuator 70 and can be switched between an engaged state in which power is transmitted between the engine 2 and the transmission 4, a released state in which power is not transmitted, and a half-clutch state in which torque is transmitted with a rotational difference. The clutch actuator 70 is connected to and controlled by the ECU 10.

[0039] The hybrid vehicle 1 includes a low-voltage battery 11. The low-voltage battery 11 is formed of, for example, a lead battery. The low-voltage battery 11 supplies power to electrical loads of the hybrid vehicle 1, such as the ISG 20, the starter motor 22, and the ECU 10.

[0040] The hybrid vehicle 1 is equipped with an accelerator pedal 90 that is operated by the driver. The amount of depression of the accelerator pedal 90 is detected by an accelerator opening sensor 91. The accelerator opening sensor 91 is connected to the ECU 10, detects the amount of depression of the accelerator pedal 90 as an accelerator opening, and transmits a signal corresponding to the accelerator opening to the ECU 10.

[0041] The ECU 10 is composed of a computer unit having a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory for storing backup data, etc., input ports, and output ports.

[0042] The ROM of the computer unit stores various constants, various maps, and the like, as well as a program for causing the computer unit to function as the ECU 10. That is, the CPU executes the program stored in the ROM using the RAM as a work area, causing the computer unit to function as the ECU 10 in this embodiment.

[0043] The hybrid vehicle 1 configured as described above runs using at least one of the engine 2 and the drive motor generator 3 as a drive source.

[0044] In this embodiment, at the initial system startup when the system of the hybrid vehicle 1 is started by operating the ignition switch, the ECU 10 determines based on the state of the hybrid vehicle 1 whether or not there is a high possibility that the engine 2 will be unable to start, and if there is a high possibility that the engine 2 will be unable to start, it performs HEV startup, which starts the engine 2 and activates the high-voltage system, and if there is no high possibility that the engine 2 will be unable to start, it performs EV startup, which starts the high-voltage system while keeping the engine 2 stopped.

[0045] Here, starting up the high-voltage system means connecting the inverter 30 and the high-voltage battery 31 so that power can be supplied to the drive motor generator 3.

[0046] For this reason, the ECU 10 includes a start control unit 101. At the initial system start-up, the start control unit 101 executes an engine start determination to determine whether or not the engine 2 is in a state where it is highly likely that it will become unable to start, based on the state of the hybrid vehicle 1.

[0047] As an engine start determination, if any of the following conditions is not met, for example, the engine 2 coolant temperature exceeds a predetermined temperature, or the voltage of the low-voltage battery 11 is higher than a predetermined voltage, it is determined that there is a high possibility that the engine 2 will be unable to start.

[0048] The start control unit 101 performs an engine water temperature determination to determine whether the coolant temperature of the engine 2 exceeds a predetermined temperature, and if the result of the engine water temperature determination indicates that the coolant temperature of the engine 2 does not exceed the predetermined temperature, it determines that there is a high possibility that the engine 2 will be unable to start.

[0049] If it is determined as a result of the engine start determination that there is a high possibility that the engine 2 will become unable to start, the start control unit 101 executes an HEV start process to start the engine 2 and start the high voltage system.

[0050] If the engine start determination determines that the engine 2 is not in a state where there is a high possibility that it will become unable to start, the start control unit 101 executes an EV start process that starts the high voltage system while keeping the engine 2 stopped.

[0051] In the HEV startup process, the startup control unit 101 starts the startup of the high voltage system after the startup of the engine 2 is completed. The completion of the startup of the engine 2 is determined, for example, when the rotation speed of the engine 2 becomes higher than a predetermined rotation speed.

[0052] The start-up control unit 101 executes a soak time determination to determine whether or not a soak time, which is the time elapsed since the system of the hybrid vehicle 1 was shut down, is less than a predetermined time. If the soak time determination determines that the soak time is not less than the predetermined time, the start-up control unit 101 executes an HEV start-up process to start the engine 2 and start the high-voltage system.

[0053] If the result of the engine start determination indicates that the engine 2 is not in a state where there is a high possibility that it will be unable to start, and the result of the soak time determination indicates that the soak time is less than a predetermined time, the start control unit 101 executes an EV start process to start the high voltage system while keeping the engine 2 stopped.

[0054] The initial system startup process performed by the control device for a hybrid vehicle according to this embodiment configured as described above will be described with reference to Fig. 3. The initial system startup process described below is started when the system of the hybrid vehicle 1 is started by operating the ignition switch.

[0055] In step S1, the ECU 10 determines whether the voltage of the low-voltage battery 11 is higher than a predetermined voltage, which is a threshold value.

[0056] If the ECU 10 determines that the voltage of the low-voltage battery 11 is higher than the predetermined voltage, the ECU 10 executes the process of step S2. If the ECU 10 determines that the voltage of the low-voltage battery 11 is not higher than the predetermined voltage, the ECU 10 executes the process of step S5.

[0057] In step S2, the ECU 10 determines whether the soak time is less than a predetermined time, which is a threshold value.

[0058] If it is determined that the soak time is less than the predetermined time, the ECU 10 executes the process of step S3. If it is determined that the soak time is not less than the predetermined time, the ECU 10 executes the process of step S5.

[0059] In step S3, the ECU 10 determines whether the coolant temperature of the engine 2 exceeds a predetermined temperature threshold.

[0060] If it is determined that the coolant temperature of the engine 2 exceeds the predetermined temperature, the ECU 10 executes the process of step S4. If it is determined that the coolant temperature of the engine 2 does not exceed the predetermined temperature, the ECU 10 executes the process of step S5.

[0061] In step S4, the ECU 10 starts up the high-voltage system. After executing the process of step S4, the ECU 10 ends the initial system startup process.

[0062] In step S5, the ECU 10 starts the engine 2. After executing the process of step S5, the ECU 10 executes the process of step S6.

[0063] In step S6, the ECU 10 determines whether the starting of the engine 2 has been completed.

[0064] If it is determined that the starting of the engine 2 is completed, the ECU 10 executes the process of step S7. If it is determined that the starting of the engine 2 is not completed, the ECU 10 executes the process of step S6.

[0065] In step S7, the ECU 10 starts up the high-voltage system. After executing the process of step S7, the ECU 10 ends the initial system startup process.

[0066] In FIG. 3, the process in step S4 is the EV startup process, and the processes in steps S5 to S7 are the HEV startup process.

[0067] As described above, in this embodiment, the start control unit 101 executes an engine start determination to determine whether or not the engine 2 is in a state where there is a high possibility that it will be unable to start, based on the state of the hybrid vehicle 1. If the result of the engine start determination indicates that the engine 2 is in a state where there is a high possibility that it will be unable to start, the start control unit 101 executes an HEV start process to start the engine 2 and activate the high-voltage system. If the result of the engine start determination indicates that the engine 2 is not in a state where there is a high possibility that it will be unable to start, the start control unit 101 executes an EV start process to activate the high-voltage system while keeping the engine 2 stopped.

[0068] When it is determined that there is a high possibility that the engine 2 will become unable to start, the engine 2 is started and the high voltage system is activated, thereby preventing the engine 2 from becoming unable to start after the hybrid vehicle 1 starts. This makes it possible to prevent the hybrid vehicle 1 from becoming unable to run after it starts.

[0069] Furthermore, in the HEV startup process, the startup control unit 101 starts the startup of the high voltage system after the startup of the engine 2 is completed.

[0070] Since the start of the high voltage system begins after the engine 2 has been started, it is possible to prevent the negative side relay 12 and the positive side relay 13 from sticking when the high voltage system is started.

[0071] When the engine 2 is cranked, the voltage of the low-voltage battery 11 drops, causing a drop in the power supply voltage of the ECU 10. If the high-voltage system starts to start up at this time, the drop in the power supply voltage of the ECU 10 causes chattering in the main relay drive output signal output from the ECU 10. At this time, arc heat is generated in the negative side relay 12 and the positive side relay 13, which may cause the negative side relay 12 and the positive side relay 13 to stick.

[0072] Furthermore, if the soak time determination determines that the soak time is not less than a predetermined time, the start-up control unit 101 executes an HEV start-up process to start the engine 2 and start the high-voltage system, and if the engine start-up determination determines that the engine 2 is not in a state where there is a high possibility that it will become unable to start and the soak time determination determines that the soak time is less than a predetermined time, the start-up control unit 101 executes an EV start-up process to start the high-voltage system while keeping the engine 2 stopped.

[0073] This allows the user to temporarily shut down the system of the hybrid vehicle 1 for a break or the like, and then avoid the hassle of starting the engine when the system of the hybrid vehicle 1 is to be started again.

[0074] In addition, the start-up control unit 101 performs an engine water temperature determination to determine whether the coolant temperature of the engine 2 exceeds a predetermined temperature. If the result of the engine water temperature determination indicates that the coolant temperature of the engine 2 is equal to or lower than the predetermined temperature, the start-up control unit 101 performs an HEV start-up process. If the result of the engine water temperature determination indicates that the coolant temperature of the engine 2 exceeds the predetermined temperature, the start-up control unit 101 performs an EV start-up process.

[0075] When it is determined that the cooling water temperature of engine 2 is below a predetermined temperature, the HEV is started, so that starting of engine 2 by ISG20 after EV start is guaranteed, and quiet starting of engine 2 after EV start can be ensured.

[0076] If the engine 2 is started by the ISG 20 in a low-temperature environment, there is a possibility that the belt 21 will break. To prevent the belt 21 from breaking, if the engine 2 coolant temperature is below a predetermined temperature, the engine 2 is started by the starter motor 22, rather than by the ISG 20. In such a case, if the EV is started, it is not possible to ensure quiet starting of the engine 2 after the EV is started. Note that when the system is started for the first time, the system is started in response to a start request from the user, so the starting noise of the engine 2 is relatively innocuous.

[0077] In this embodiment, a configuration in which the output shaft of the drive motor generator 3 and the output shaft of the transmission 4 are connected is shown, but this is not limited to this, and the same can be implemented in any hybrid vehicle that has an EV mode in which the vehicle runs only on the power output by the drive motor generator 3, and an HEV mode in which the engine 2 is started and the vehicle runs on the power output by the engine 2 and the drive motor generator 3.

[0078] In this embodiment, an example has been described in which the ECU 10 performs various determinations and calculations based on various sensor information, but this is not limited to this. The hybrid vehicle 1 may be provided with a communication unit capable of communicating with an external device such as an external server, and various determinations and calculations may be performed by the external device based on the detection information of the various sensors transmitted from the communication unit. The determination results and calculation results may be received by the communication unit, and various controls may be performed using the received determination results and calculation results.

[0079] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0080] 1 Hybrid vehicle 2 engines 3. Drive motor generator 10 ECU 11 Low voltage battery 12 Negative relay (main relay) 13 Positive relay (main relay) 20 ISG (engine starting device, motor generator) 21 Belt (belt component) 22 Starter motor (engine starting device) 23 Water temperature sensor 30 inverters 31 High Voltage Battery 101 Start control unit

Claims

[Claim 1] The vehicle is equipped with an engine and a high-voltage system that drives a drive motor generator, A control device for a hybrid vehicle that runs using at least one of the engine and the drive motor generator as a drive source, a startup control unit that executes an initial system startup process for the hybrid vehicle; The start control unit performs an engine start determination to determine whether the engine is in a state where there is a high possibility that it will be unable to start, and a soak time determination to determine whether the soak time is less than a predetermined time, based on the state of the hybrid vehicle; if the result of the engine start determination determines that the engine is in a state where there is a high possibility that it will be unable to start, or if the result of the soak time determination determines that the soak time is not less than the predetermined time, the start control unit performs an HEV start process to start the engine and activate the high-voltage system; and if the result of the engine start determination determines that the engine is not in a state where there is a high possibility that it will be unable to start, and the result of the soak time determination determines that the soak time is less than the predetermined time, the start control unit performs an EV start process to start the high-voltage system while keeping the engine stopped.

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