Hybrid vehicle control device

Abstract

To provide a control device of a hybrid vehicle which can highly accurately perform control during a stop of an engine without impairing the restartability of the engine.SOLUTION: A control device for performing processing for controlling a hybrid vehicle comprises an engine, a power generation motor to which an output of the engine is transmitted, and a battery for accumulating power generated by the power generation motor. The control device performs fuel supply stop control for stopping fuel supply to the engine when a prescribed engine stop condition is satisfied, and stop position adjustment control for stopping a crankshaft of the engine at a prescribed position by a drive force of the power generation motor. When engine cooling water is within a prescribed range during the execution of the stop position adjustment control, the control device performs ignition stop control for stopping the ignition of an ignition plug of the engine. When a prescribed time elapses after a start of the ignition stop control, the control device performs ignition restart control for restarting the ignition of the ignition plug even if a temperature of the engine cooling water is within a prescribed range.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] In a hybrid vehicle equipped with an engine and a motor, when a predetermined condition is satisfied, a control for stopping the engine is executed. When stopping the engine, a fuel supply stop control (fuel cut) that stops the supply of fuel to the engine, an ignition stop control (ignition cut) that stops the ignition of the engine's spark plugs, etc. are executed. When stopping the engine, a stop position adjustment control may be executed that uses the driving force of the motor to stop the engine crankshaft at a predetermined position (predetermined rotation angle). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-97071 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-32383 [Patent Document 3] JP 2018-34750 A Summary of the Invention [Problem to be solved by the invention]

[0004] When stopping the engine, if residual fuel remaining in the engine burns, the engine may output unintended torque. Such engine torque caused by the combustion of residual fuel can reduce the accuracy of the stop position adjustment control. While it is possible to execute ignition stop control to suppress the effects of the combustion of residual fuel, executing ignition stop control can cause a drop in engine temperature and potentially worsen the restartability of the engine.

[0005] An object of the present invention is to provide a control device for a hybrid vehicle that can execute control with high precision when the engine is stopped without impairing the restartability of the engine. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, one embodiment of the present invention is a control device that executes processing to control a hybrid vehicle having an engine, a generator motor to which the output of the engine is transmitted, and a battery that stores the electricity generated by the generator motor, and when a predetermined engine stop condition is met, executes fuel supply stop control that stops the supply of fuel to the engine, and stop position adjustment control that stops the engine crankshaft at a predetermined position using the driving force of the generator motor, and is characterized in that when the stop position adjustment control is executed, if the engine coolant is within a predetermined range, it executes ignition stop control that stops ignition of the engine's spark plug, and executes ignition restart control that restarts ignition of the spark plug when a predetermined time has elapsed after the start of the ignition stop control.

[0007] According to the above configuration, when the stop position adjustment control is executed, if the coolant temperature is within a predetermined range, fuel supply to the engine is stopped and ignition of the spark plug is stopped. This makes it possible to suppress the generation of unintended engine torque due to the combustion of residual fuel and improve the accuracy of the stop position adjustment control. Furthermore, when a predetermined time has elapsed since ignition was stopped, ignition is resumed regardless of the coolant temperature. This makes it possible to suppress an excessive drop in engine temperature due to ignition stop and improve the restartability of the engine.

[0008] In the above configuration, the predetermined time may be a time until the engine rotates a predetermined number of cycles.

[0009] According to the above configuration, the timing to restart ignition can be determined according to the actual operating conditions of the engine after the ignition stop control. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a control device for a hybrid vehicle that can execute control with high precision when the engine is stopped without impairing the restartability of the engine. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating an example of a system configuration of a hybrid vehicle according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of a functional configuration of the ECU according to the embodiment. [Figure 3] FIG. 3 is a flowchart illustrating an example of a process performed by the ECU when the engine is stopped according to the embodiment. [Figure 4] FIG. 4 is a diagram showing an example of a time series change in engine speed when the engine is stopped in a comparative example. [Figure 5] FIG. 5 is a diagram showing an example of a time series change in the engine rotation rate when the engine is stopped in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The configuration of the embodiment described below and the actions and effects brought about by the configuration are merely examples, and the present invention is not limited to the following description.

[0013] 1 is a diagram showing an example of a system configuration of a hybrid vehicle according to an embodiment. The hybrid vehicle according to the embodiment includes an engine 1, a generator motor 2 that is driven by the engine 1 to generate electricity, a battery 3 that stores the electricity generated by the generator motor 2, and a traction motor 4 that receives electricity from the generator motor 2 and / or the battery 3 to drive drive wheels 62 of the vehicle.

[0014] The hybrid vehicle illustrated here is a so-called series hybrid vehicle in which the engine 1 is used only for generating electricity, and the driving force for driving is supplied exclusively to the drive wheels 62 from the traction motor 4. The engine 1 and the drive wheels 62 are mechanically separated, and no rotational driving force is inherently transmitted between them. In other words, the engine 1 rotates completely independently of the traction motor 4 and the drive wheels 62, and can also be stopped completely independently. Therefore, while the ignition switch (power switch or ignition key) is turned ON and the vehicle is ready to drive when the driver depresses the accelerator pedal, the engine 1 may not operate, which involves burning fuel, if the battery 3 has sufficient charge stored and the brake booster has sufficient negative pressure stored.

[0015] The crankshaft, which is the rotating shaft of the engine 1, is mechanically connected to the rotating shaft of the generator motor 2 via a gear mechanism. The driving force output by the engine 1 is input to the generator motor 2, which then generates electricity. The electricity generated by the generator motor 2 is charged into a battery 3. The electricity generated by the generator motor 2 and / or the electricity charged into the battery 3 is supplied to a traction motor 4.

[0016] The generator motor 2 also functions as an electric motor for motoring (cranking) that generates driving force (output torque) by itself to rotate the crankshaft of the engine 1. When starting the engine 1, the DC power output from the battery 3 is converted to AC power by the generator inverter 21, and the AC power is supplied to the generator motor 2. This causes the generator motor 2 to operate in power running mode, and the crankshaft of the engine 1 is rotated by the driving force of the generator motor 2. When the rotation speed of the crankshaft of the engine 1 has increased to the rotation speed required for starting by this motoring, the ignition plug of the engine 1 is ignited, and the engine 1 starts.

[0017] Furthermore, when the engine 1 is stopped, stop position adjustment control is executed to stop the crankshaft of the engine 1 at a predetermined position (predetermined rotation angle) using the driving force of the generator motor 2. The stop position adjustment control is a control for optimizing the stop positions of predetermined members such as the crank pin and piston so that the engine 1 can operate stably and efficiently when restarting the stopped engine 1.

[0018] The battery 3 is a unit that stores electric charge and may be a high-voltage secondary battery with a high energy density, such as a lithium-ion secondary battery or a nickel-metal hydride secondary battery. The battery 3 stores the electric power generated by the generator motor 2 and the traction motor 4. The battery 3 also discharges the electric power required to operate the generator motor 2 and the traction motor 4 as electric motors, and supplies the electric power required for them.

[0019] The traction motor 4 generates driving force for propelling the vehicle and inputs this driving force to the drive wheels 62 via a reduction gear 61. The traction motor 4 also generates electricity by rotating in response to the rotational force of the drive wheels 62, recovering the vehicle's kinetic energy as electrical energy. The electricity generated by this regenerative braking is charged to the battery 3. However, if the battery 3 is already fully charged and further charging is difficult, the electric power regenerated by the traction motor 4 can be supplied to the generator motor 2, which can then be operated as an electric motor to rotate the engine 1. This allows the vehicle's braking performance to be maintained while consuming excess electric power. Furthermore, since the engine 1 continues to rotate at this time, the fuel supply to the engine 1 can be temporarily stopped.

[0020] The generator inverter 21 converts AC power generated by the generator motor 2 into DC power and inputs the DC power to the battery 3 or the driving machine inverter 41. When the generator motor 2 is operated as an electric motor, the generator inverter 21 also converts DC power supplied from the battery 3 and / or the driving machine inverter 41 into AC power and inputs it to the generator motor 2.

[0021] The drive machine inverter 41 converts DC power supplied from the battery 3 and / or the generator inverter 21 into AC power and inputs it to the traction motor 4. In addition, the drive machine inverter 41 converts AC power generated by the traction motor 4 when performing regenerative braking of the vehicle into DC power and inputs it to the battery 3 or the generator inverter 21.

[0022] The ECU (Electronic Control Unit) 0 (an example of a control device) is an information processing device that controls the engine 1, the generator motor 2, the battery 3, the traction motor 4, the generator inverter 21, and the drive machine inverter 41. The ECU 0 can be configured using, for example, a processor, a memory, an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), an input interface, an output interface, and the like. The ECU 0 illustrated here is configured by connecting multiple ECUs, such as an EFI (Electronic Fuel Injection) ECU 01, a generator ECU 02, a BMS (Battery Management System) ECU 03, a drive machine ECU 04, and an HV (Hybrid Vehicle) ECU 00, to each other so that they can communicate with each other via an electrical communication line such as a CAN (Controller Area Network). The EFI ECU 01 executes processing to control the engine 1. The generator ECU 02 executes processing to control the generator motor 2 and the generator inverter 21. The BMS ECU 03 executes processing to control the battery 3. The drive machine ECU04 executes processing for controlling the drive motor 4 and the drive machine inverter 41. The HV ECU00 is an ECU as a higher-level controller that executes processing for managing the control of the above ECUs 01 to 04.

[0023] The ECU 0 acquires vehicle information including various types of information related to the vehicle from various sensors mounted on the vehicle, and executes various processes based on the vehicle information to control the engine 1, the generator motor 2, the battery 3, the driving motor 4, the generator inverter 21, the drive machine inverter 41, etc. The vehicle information includes, for example, the accelerator opening, the shift position, the vehicle speed, the gradient of the road surface, the remaining battery charge (such as the amount of charge stored in the battery 3), the power generation capacity of the generator motor 2, the coolant temperature (the temperature of the engine coolant), etc.

[0024] The ECU 0 of this embodiment has a function to suppress problems caused by the combustion of residual fuel when the engine 1 is stopped, and to improve the accuracy, stability, etc. of various controls when the engine 1 is stopped.

[0025] 2 is a diagram showing an example of the functional configuration of the ECU 0 according to the embodiment. The ECU 0 has a motoring control unit 101, a fuel supply control unit 102, and an ignition control unit 103. These functional units 101 to 103 may be configured in cooperation with hardware elements and software elements (programs, etc.) that constitute the ECU 0. Furthermore, at least one of these functional units 101 to 103 may be configured by dedicated hardware (circuits, etc.).

[0026] The motoring control unit 101 controls motoring, which rotates the crankshaft of the engine 1 using the driving force of the generator motor 2. In this embodiment, the motoring control unit 101 executes stop position adjustment control, which stops the crankshaft of the engine 1 at a predetermined position using the driving force of the generator motor 2 when stopping the engine 1. The stop position adjustment control is control for optimizing the stop positions of predetermined members such as the crank pin and piston so that the engine 1 can operate stably and efficiently when restarting the engine 1 from a stopped state.

[0027] When predetermined engine stop conditions are satisfied as conditions for stopping the engine 1, the motoring control unit 101 executes fuel supply stop control to stop the fuel supply to the engine 1. The engine stop conditions should be set appropriately depending on the vehicle specifications and the like, and can be set based on, for example, the remaining battery charge, the driving state (accelerator opening, vehicle speed, road gradient, etc.), etc.

[0028] The ignition control unit 103 controls the ignition (for example, ignition timing, applied voltage, etc.) of the spark plug of the engine 1. The ignition control unit 103 of this embodiment executes ignition stop control and ignition restart control.

[0029] Ignition stop control is control that stops ignition of the spark plug when the temperature of the engine coolant (coolant temperature) is within a predetermined range when stop position adjustment control is being executed by the motoring control unit 101. The predetermined range is a temperature range that is set in consideration of the combustibility of residual fuel remaining in the engine 1 (for example, in the cylinder that houses the piston), and should be set appropriately depending on the structure and specifications of the engine 1, but can be, for example, a range of 20°C to 60°C.

[0030] The ignition restart control is a control that restarts ignition of the spark plug when a predetermined time has elapsed since the start of the ignition stop control during execution of the stop position adjustment control. The predetermined time is set taking into consideration the deterioration of the restartability of the engine 1 due to a temperature drop in the engine 1 caused by the ignition stop, and should be set appropriately depending on the structure and specifications of the engine 1. The predetermined time may be a fixed time that is determined in advance, or may be a time that varies depending on the situation. For example, the predetermined time may be the time until the engine 1 rotates a predetermined number of cycles. In this case, the method of counting the number of cycles is not particularly limited, but for example, in the case of a four-cycle engine, one cycle can be the period during which the four processes of intake, compression, combustion, and exhaust are completed.

[0031] Figure 3 is a flowchart showing an example of the processing when the engine is stopped by the ECU0 of the embodiment. The ECU0 determines whether a predetermined engine stop condition is satisfied based on the vehicle information acquired from various sensors (S101). When the engine stop condition is not satisfied (S101: No), the ECU0 continues the fuel supply to the engine 1 and the ignition of the spark plug (S102), and ends this routine.

[0032] On the other hand, when the engine stop condition is satisfied (S101: Yes), the fuel supply control unit 102 executes fuel supply stop control to stop the fuel supply to the engine 1 (S103), and the motoring control unit 101 executes stop position adjustment control to stop the crankshaft of the engine 1 at a predetermined position by the driving force of the power generation motor 2 (S104).

[0033] Thereafter, the ignition control unit 103 determines whether the coolant temperature T is within a predetermined range (a range higher than temperature T1 and lower than temperature T2: T1 < T2) (S105). As described above, the predetermined range is a temperature range set in consideration of the combustibility of the residual fuel and should be appropriately set according to the structure and specifications of the engine 1, etc., and can be, for example, a range of 20°C to 60°C. That is, temperature T1 is the lower limit value of the predetermined range or a value in the vicinity thereof, and temperature T2 is the upper limit value of the predetermined range or a value in the vicinity thereof. When the coolant temperature T is not within the predetermined range (S105: No), the ignition control unit 103 continues the ignition of the spark plug (S106), and ends this routine. At this time, the fuel supply is stopped and the ignition continues.

[0034] On the other hand, when the coolant temperature T is within the predetermined range (S105: Yes), the ignition control unit 103 executes ignition stop control to stop the ignition of the spark plug (S107). At this time, the fuel supply is stopped and the ignition is stopped.

[0035] Thereafter, the ignition control unit 103 determines whether a predetermined time has elapsed since the start of the ignition stop control (S108). If the predetermined time has not elapsed (S108: No), the processing from step S105 onward is executed again. If the predetermined time has elapsed (S108: Yes), the ignition control unit 103 executes ignition restart control to restart ignition of the spark plug (S109) and ends this routine. At this time, the ignition restart control is executed regardless of whether the coolant temperature T is within a predetermined range.

[0036] As described above, according to this embodiment, when the stop position adjustment control is executed, if the coolant temperature is within a predetermined range, fuel supply to the engine 1 is stopped and ignition is stopped. This makes it possible to suppress combustion of the residual fuel when the coolant temperature is within the predetermined range, i.e., in a situation where the combustibility of the residual fuel is estimated to be relatively high. This makes it possible to suppress the adverse effect of unintended engine torque generated by the combustion of the residual fuel on the stop position adjustment control, thereby improving the accuracy of the stop position adjustment control. Furthermore, according to this embodiment, ignition is resumed regardless of the coolant temperature when a predetermined time has elapsed since the ignition was stopped as described above. This makes it possible to suppress an excessive temperature drop of the engine 1 due to the ignition being stopped, thereby improving the restartability of the engine 1.

[0037] Fig. 4 is a diagram showing an example of a time series change in engine speed when the engine is stopped in a comparative example. Fig. 5 is a diagram showing an example of a time series change in engine rotation rate when the engine is stopped in an embodiment.

[0038] In Figures 4 and 5, line L1 indicates the time-series change in instantaneous engine speed. Line L2 indicates the time-series change in engine speed when line L1 is subjected to a predetermined smoothing process (e.g., moving average method, etc.). Time t1 indicates the point in time when the engine stop condition is met. The FC (Fuel Cut) flag indicates the timing of execution / stop of fuel supply cut control. Here, the value of the FC flag is 0 when the fuel supply cut control is stopped, and the value of the FC flag is 1 when the fuel supply cut control is executed. The injection signal indicates the timing of fuel injection into each cylinder of the engine 1. Here, a case is illustrated in which the engine 1 is a three-cylinder engine, and fuel is injected into the first cylinder when the injection signal value is 1, fuel is injected into the second cylinder when the injection signal value is 2, and fuel is injected into the third cylinder when the injection signal value is 4. The ignition signal indicates the ignition timing of the spark plug of each cylinder of the engine 1. Here, an example is shown in which engine 1 is a three-cylinder engine, and when the value of the ignition signal is 4, the spark plug of the first cylinder is ignited, when the value of the ignition signal is 1, the spark plug of the second cylinder is ignited, and when the value of the ignition signal is 2, the spark plug of the third cylinder is ignited.

[0039] In the comparative example shown in FIG. 4 , the spark plug continues to fire after time t1 when the engine stop condition is satisfied, i.e., during execution of the stop position adjustment control, which stops the crankshaft of the engine 1 at a predetermined position by motoring. In this case, as shown by line L2 in FIG. 4 , when the time series change in the engine speed is viewed macroscopically, the engine speed gradually decreases over time. However, as shown by line L1 in FIG. 4 , when the time series change in the engine speed is viewed microscopically, multiple instantaneous peaks P appear, where the engine speed momentarily increases, after the fuel supply is stopped (when the stop position adjustment control is executed). This phenomenon is caused by the residual fuel remaining in each cylinder being burned by the ignition of the spark plug, and occurs particularly noticeably when the coolant temperature (temperature of the engine 1) is within the predetermined range as described above. The unintended engine torque generated by such instantaneous peaks P can reduce the accuracy of the stop position adjustment control.

[0040] On the other hand, in this embodiment, as shown in Fig. 5, after time t1 when the engine stop condition is satisfied, i.e., when the stop position adjustment control is executed, if the coolant temperature is within a predetermined range, ignition of the spark plug is stopped and resumed after a predetermined time Δt has elapsed. This control can suppress combustion of residual fuel when the stop position adjustment control is executed. Therefore, as shown by line L1 in Fig. 5, even when the time series change in engine speed is observed microscopically, a phenomenon in which the engine speed momentarily increases (instantaneous peak P on line L1 in Fig. 4) is not observed. Furthermore, by resuming ignition after the predetermined time Δt has elapsed, as described above, excessive temperature drops in the engine 1 can be suppressed, thereby improving the restartability of the engine 1.

[0041] As described above, according to this embodiment, it is possible to improve the accuracy of the stop position adjustment control without impairing the restartability of the engine 1.

[0042] In the above embodiment, a series hybrid vehicle has been described as an example, but the embodiment of the present invention can also be applied to hybrid vehicles of types other than the series type, such as so-called parallel type or split type.

[0043] The program that causes a computer (e.g., ECU0) to execute processes for realizing various functions in the control device for a hybrid vehicle according to the above-described embodiment can be provided by being recorded in an installable or executable file format on a computer-readable recording medium such as a CD (Compact Disc)-ROM, a flexible disk (FD), a CD-R (Recordable), a DVD (Digital Versatile Disk), etc. The program may also be provided or distributed via a network such as the Internet.

[0044] Although the embodiments of the present invention have been described above, the above-described embodiments are presented as examples and are not intended to limit the scope of the present invention. This novel embodiment can be embodied in various other forms. Furthermore, various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Furthermore, this embodiment is included within the scope and spirit of the invention, and is also included in the inventions and their equivalents as defined in the claims. [Explanation of symbols]

[0045] 0...ECU, 1...engine, 2...generator motor, 3...battery, 4...travel motor, 21...generator inverter, 41...drive machine inverter, 61...reduction gear, 62...drive wheels, 101...motoring control unit, 102...fuel supply control unit, 103...ignition control unit, P...instantaneous peak

Claims

[Claim 1] A control device that executes processing to control a hybrid vehicle including an engine, a power generation motor to which an output of the engine is transmitted, and a battery that stores electric power generated by the power generation motor, When a predetermined engine stop condition is satisfied, a fuel supply stop control is executed to stop the fuel supply to the engine, and a stop position adjustment control is executed to stop the crankshaft of the engine at a predetermined position by the driving force of the generator motor, When the stop position adjustment control is executed, if the engine coolant temperature is not within a predetermined range that is set taking into consideration the combustibility of the residual fuel remaining in the engine, the ignition of the spark plug is continued, and if the engine coolant temperature is within the predetermined range, the ignition stop control is executed so as to prevent an instantaneous peak in the engine speed from appearing during the period from the end of the fuel supply stop control until the execution of ignition stop control that stops ignition of the spark plug of the engine, and the ignition restart control is executed to restart ignition of the spark plug when a time has passed during which the engine has rotated a predetermined number of cycles after the start of the ignition stop control. A control device for a hybrid vehicle.

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