Hybrid vehicle control device

Abstract

To provide a control device of a hybrid vehicle ensuring startability even if abnormality relating to a motor is generated.SOLUTION: A control device of a hybrid vehicle is provided with a motor on a power transmission path between an engine and wheels and is provided with a clutch between the engine and the motor on the power transmission path. The control device of a hybrid vehicle is equipped with an obtaining portion that obtains engine speed, a first determining portion that determines whether or not the engine is being driven and the clutch is in either one of a slip state or an engaged state, a second determining portion that determines whether or not the engine speed drops from a target engine speed, a third determining portion that determines whether or not there is abnormality relating to the motor, and a correcting portion that, when a positive determination is made by the first, second, and third determining portions, increases the output torque of the engine as compared with the case where a positive determination is made by the first and second determining portions and a negative determination is made by the third determining portion.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] A hybrid vehicle is known in which a motor is provided on a power transmission path between an engine and wheels, and a clutch is provided between the engine and the motor on the power transmission path. In such a hybrid vehicle, if an abnormality occurs in the motor and the motor cannot be started, the clutch is released to start the engine, and then the clutch is engaged to forcibly rotate the motor by the engine, thereby starting the hybrid vehicle (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-011072 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, because the motor needs to be forcibly rotated by the engine, there is a risk that the engine speed will drop and the engine will stall when the clutch is engaged, which may result in poor startability.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a control device for a hybrid vehicle that ensures startability even when an abnormality occurs in the motor. [Means for solving the problem]

[0006] The object of the present invention is to provide a control device for a hybrid vehicle, the control device including a motor provided on a power transmission path between an engine and wheels, and a clutch provided between the engine and the motor on the power transmission path, the control device including: an acquisition unit that acquires a rotation speed of the engine; a first determination unit that determines whether the engine is in operation and whether the clutch is in either a slip state or an engaged state; Idol A second determination unit that determines whether or not the rotation speed has decreased, and a third determination unit that determines whether or not an abnormality exists regarding the motor. a correction unit that performs a correction to increase the output torque of the engine when a positive determination is made by the first and second determination units compared to when a negative determination is made by the first or second determination unit, and an increase in the output torque of the engine by the correction is When the first, second, and third determination units make a positive determination, It is better to than when the first and second determination units make a positive determination and the third determination unit makes a negative determination big, This can be achieved by a control device for a hybrid vehicle. Effect of the Invention

[0007] According to the present invention, it is possible to provide a control device for a hybrid vehicle that ensures startability even when an abnormality occurs in the motor. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle. [Diagram 2] FIG. 2 is a timing chart showing changes in the engine speed and the motor speed in the comparative example. [Diagram 3] FIG. 3 is a flowchart showing an example of the output torque increase control executed by the ECU. [Figure 4] 4A and 4B are examples of maps that define the torque increase amounts in the output torque increase corrections A and B, respectively. [Diagram 5] FIG. 5 is a timing chart showing the transition of the engine rotation speed and the motor rotation speed in this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [General configuration of hybrid vehicle] FIG. 1 is a schematic diagram of a hybrid vehicle. The hybrid vehicle is equipped with an engine 10 and a motor 15 as driving sources for traveling. The engine 10 is, for example, a gasoline engine, but may be a diesel engine. The engine 10 is provided with a starter 24 for cranking and starting the engine 10. A transmission unit 11 is provided on a power transmission path from the engine 10 to wheels 13. The transmission unit 11 and the left and right wheels 13 are drivingly connected via a differential 12.

[0010] The transmission unit 11 is provided with a K0 clutch 14 and a motor 15. In the transmission unit 11, the motor 15 is installed so as to be located on a power transmission path from the engine 10 to the wheels 13. The K0 clutch 14 is provided between the engine 10 and the motor 15 on the power transmission path. When supplied with hydraulic pressure, the K0 clutch 14 changes from a released state to a slip state and then to an engaged state, thereby connecting the power transmission between the engine 10 and the motor 15. When the supply of hydraulic pressure is stopped, the K0 clutch 14 changes to a released state and cuts off the power transmission between the engine 10 and the motor 15.

[0011] The motor 15 is connected to the vehicle battery 16 via an inverter 17. The motor 15 functions as a motor that generates driving force for the vehicle in response to power supplied from the vehicle battery 16, and also functions as a generator that generates electric power to charge the vehicle battery 16 in response to power transmission from the engine 10 and the wheels 13.

[0012] The inverter 17 adjusts the power exchanged between the motor 15 and the vehicle-mounted battery 16. Specifically, the inverter 17 converts the direct current input from the vehicle-mounted battery 16 into a three-phase alternating current and outputs it to the motor 15, and also converts the three-phase alternating current input from the motor 15 into a direct current and charges the vehicle-mounted battery 16.

[0013] The transmission unit 11 is provided with a torque converter 18, which is a fluid coupling having a torque amplifying function, and a stepped automatic transmission 19 that switches the gear ratio in multiple stages by switching the gear stage. In the transmission unit 11, the automatic transmission 19 is provided between the motor 15 and the wheels 13 on the power transmission path. The motor 15 and the automatic transmission 19 are connected via the torque converter 18. The torque converter 18 is provided with a lock-up clutch 20 that is supplied with hydraulic pressure and enters an engaged state to directly connect the motor 15 and the automatic transmission 19.

[0014] The transmission unit 11 is further provided with an oil pump 21 and a hydraulic control mechanism 22. The hydraulic pressure generated by the oil pump 21 is supplied to the K0 clutch 14, the torque converter 18, the automatic transmission 19, and the lock-up clutch 20 via the hydraulic control mechanism 22. The hydraulic control mechanism 22 is provided with hydraulic circuits for each of the K0 clutch 14, the torque converter 18, the automatic transmission 19, and the lock-up clutch 20, and various hydraulic control valves for controlling the operating hydraulic pressures thereof.

[0015] The hybrid vehicle is provided with an ECU (Electronic Control Unit) 23. The ECU 23 is an electronic control unit including a calculation processing circuit that performs various calculation processes related to vehicle driving control, and a memory that stores control programs and data. The ECU 23 is an example of a control device for the hybrid vehicle, and functionally realizes an acquisition unit, a first determination unit, a second determination unit, a third determination unit, and a correction unit, which will be described in detail later.

[0016] The ECU 23 controls the operation of the engine 10 and the motor 15. For example, the ECU 23 controls the throttle opening, ignition timing, and fuel injection amount of the engine 10 to control the torque of the engine 10. The ECU 23 also controls the inverter 17 to adjust the amount of power exchanged between the motor 15 and the vehicle battery 16 to control the torque of the motor 15. Furthermore, the ECU 23 controls the operation of the K0 clutch 14, the lock-up clutch 20, and the automatic transmission 19 through the control of the hydraulic control mechanism 22. The ECU 23 receives detection signals such as an engine speed sensor 25 that detects the rotation speed of the crankshaft of the engine 10, and an accelerator pedal opening degree, which is the amount of depression of the accelerator pedal by the driver.

[0017] [Startability during evacuation driving in comparison example] For example, if a short circuit occurs in the inverter 17 that supplies power to the motor 15, the motor 15 will not operate normally. For example, if such an abnormality occurs while the hybrid vehicle is running and the engine 10 stalls, the hybrid vehicle must then be driven to an evacuation site. The startability in such a case will be described in a comparative example.

[0018] 2 is a timing chart showing the transition of the rotation speed [rpm] of the engine 10 and the rotation speed [rpm] of the motor 15 in the comparative example. For example, if a short circuit occurs in the inverter 17 during idling operation with the K0 clutch 14 engaged and the engine 10 and the motor 15 driven, the motor 15 cannot be driven and the rotation speed of the engine 10 drops together with the motor 15 (time t1). If the rotation speed of the engine 10 drops further, the engine 10 stalls and the engine 10 and the motor 15 stop (time t2). If the ignition is subsequently turned on to perform evacuation running, the K0 clutch 14 is released and the engine 10 is started by the starter 24 (time t3), and the rotation speed of the engine 10 is maintained at the target idle rotation speed (time t4). When the K0 clutch 14 subsequently slips (time t5), the motor 15 cannot start by itself, so most of the output torque of the engine 10 is consumed by the rotation of the motor 15, and the engine 10 speed drops significantly below the target idle speed. When the K0 clutch 14 subsequently engages (time t6), the engine 10 speed cannot be maintained at the target idle speed due to insufficient output torque of the engine 10, and the engine 10 may stall again. In this way, the startability during evacuation running may be degraded. Therefore, the ECU 23 of this embodiment executes the following output torque increase control.

[0019] [Output torque increase control] 3 is a flowchart showing an example of the output torque increase control executed by the ECU 23. This control is repeatedly executed while the ignition of the hybrid vehicle is on. First, the ECU 23 determines whether the engine 10 is running (step S1). The determination in step S1 can be made based on the detection value of the engine speed sensor 25.

[0020] Next, the ECU 23 determines whether the state of the K0 clutch 14 is either a slip state or an engaged state (step S2). In step S2, the ECU 23 may determine that the state of the K0 clutch 14 is either a slip state or an engaged state if the detection value of the hydraulic sensor supplied to the K0 clutch 14 is greater than a value indicating that the K0 clutch 14 is in a slip state. The processes of steps S1 and S2 are an example of the process executed by the first determination unit. If the result of either step S1 or S2 is No, the present control is terminated.

[0021] If the results of steps S1 and S2 are Yes, the ECU 23 acquires the rotation speed of the engine 10 based on the detection value of the engine rotation speed sensor 25 (step S3). The process of step S3 is an example of a process executed by an acquisition unit.

[0022] Next, the ECU 23 determines whether the rotation speed of the engine 10 has decreased from the target rotation speed (step S4). The process of step S4 is an example of a process executed by the second determination unit. If the result of step S4 is No, this control ends. For example, if the rotation speed of the engine 10 has increased above the target rotation speed, the result of step S4 is No.

[0023] If the answer is Yes in step S4, the ECU 23 determines whether or not the value of an execution flag for three-phase ON control that is executed when there is a short circuit abnormality in the inverter 17 (hereinafter referred to as an abnormality-time three-phase ON flag) is "1" (step S5). If the value of the abnormality-time three-phase ON flag is "1", it indicates that the three-phase ON control is being executed, and if the value is "0", it indicates that the three-phase ON control is not being executed.

[0024] The three-phase ON control is a control executed when a short circuit abnormality occurs in the inverter 17. Specifically, the three-phase ON control is a control in which, if the shorted arm of the inverter 17 is the upper arm, all the upper arms of the three phases are kept ON and the lower arms are kept OFF, and, if the shorted arm is the lower arm, all the lower arms of the three phases are kept ON and the upper arm is kept OFF. This makes it possible to prevent an overcurrent from flowing through the short circuit and causing the motor 15 to heat up excessively. Note that even during the execution of the three-phase ON control, the motor 15 cannot be driven independently. The process of step S5 is an example of a process executed by the third determination unit.

[0025] If the answer is Yes in step S5, the ECU 23 executes output torque increase correction A (step S6). If the answer is No in step S5, the ECU 23 executes output torque increase correction B (step S7). Both output torque increase corrections A and B are corrections that increase the output torque of the engine 10 by an amount of torque increase calculated based on a map described below, compared to when the output torque increase correction is not executed. The increase in the output torque of the engine 10 can be achieved by controlling the throttle opening, ignition timing, and fuel injection amount. The processes of steps S6 and S7 are examples of processes executed by a correction unit.

[0026] 4A and 4B are examples of maps that define the torque increase amount in output torque increase corrections A and B, respectively. In FIG. 4A and FIG. 4B, the horizontal axis indicates the change in the rotation speed of engine 10 per unit time [rpm / msec], and the vertical axis indicates the torque increase amount [N·m]. FIG. 4A and FIG. 4B also show the torque increase amount in the case of rotation speed shortages β1 and β2, which are values ​​obtained by subtracting the rotation speed of engine 10 from the target rotation speed. The rotation speed shortage β1 is a value greater than zero. The rotation speed shortage β2 is a value greater than the rotation speed shortage β1.

[0027] Although the maps of Figures 4A and 4B only show two cases of the insufficient rotation speed, β1 and β2, in reality, the torque increase amount is specified for each insufficient rotation speed. In detail, the maps of Figures 4A and 4B specify that when the amount of change in the rotation speed of the engine 10 is a constant negative value, the torque increase amount increases as the insufficient rotation speed increases. Here, when the amount of change in the rotation speed of the engine 10 is a negative value, it indicates that the rotation speed of the engine 10 is decreasing. When the amount of change in the rotation speed of the engine 10 is a positive value, it indicates that the rotation speed of the engine 10 is increasing. When the amount of change in the rotation speed of the engine 10 is zero, it indicates that the rotation speed of the engine 10 is constant.

[0028] 4A and 4B, the greater the insufficient rotation speed, the greater the torque increase amount, and the greater the decrease in the rotation speed of the engine 10, the greater the torque increase amount. This is because the greater the insufficient rotation speed and the greater the decrease in the rotation speed of the engine 10, the greater the torque required to increase the rotation speed of the engine 10 to the target rotation speed.

[0029] Moreover, under the condition that the amount of decrease in the number of revolutions of the engine 10 is the same and the number of revolutions that is insufficient is also the same, the output torque increase correction A has a larger torque increase amount than the output torque increase correction B. The output torque increase correction A is a correction that increases the output torque of the engine 10 during execution of the three-phase ON control that is executed when an abnormality occurs in which the motor 15 cannot be driven alone. In contrast, the output torque increase correction B is a correction that increases the output torque of the engine 10 when no abnormality occurs in the motor 15, as will be described in detail later. During execution of the three-phase ON control, the motor 15 needs to be forcibly rotated by the engine 10, and the output torque increase correction A is specified to have a larger torque increase amount than the output torque increase correction B by that amount. As a result, even when an abnormality occurs in the motor 15, the output torque of the engine 10 can be increased without being excessive or insufficient with respect to the required torque, and startability is ensured.

[0030] The output torque increase correction B is determined mainly in consideration of the decrease in the output torque of the motor 15 during low-temperature start. During low-temperature start, the temperature of the lubricating oil used in the K0 clutch 14, the motor 15, and the automatic transmission 19 is low, so the viscosity is high, and the friction torque of these increases. As a result, when the output torque of the motor 15 decreases below the desired output torque and the K0 clutch 14 enters a slip state, the engine 10 cannot compensate for the decrease in the output torque of the motor 15, and the rotation speed of the engine 10 may decrease below the target idle rotation speed. In order to avoid such a decrease in the rotation speed of the engine 10, the output torque increase correction B is executed. As a result, even during low-temperature start, the output torque of the engine 10 can be increased without being excessive or insufficient with respect to the required torque, and startability is ensured.

[0031] [Startability during evacuation driving in this embodiment] Next, the startability during evacuation running of the hybrid vehicle in this embodiment will be described. Fig. 5 is a timing chart showing the rotation speed of the engine 10 and the rotation speed of the motor 15 in this embodiment. In the timing chart of Fig. 5, a case will be described as an example in which a short circuit abnormality of the inverter 17 is detected and three-phase ON control is started after evacuation running is started and the K0 clutch 14 is engaged. Also, Fig. 5 corresponds to Fig. 2, and since it is the same as Fig. 2 up to time t5, overlapping explanations will be omitted.

[0032] When the K0 clutch 14 enters a slip state (time t5), the motor 15 cannot start by itself, so the rotation speed of the engine 10 begins to decrease from the target rotation speed, but at this time, no short circuit abnormality in the inverter 17 has been detected, so output torque increase correction B is performed. This suppresses the decrease in rotation speed of the engine 10 more than in the case shown in Figure 2. However, when the K0 clutch 14 is subsequently engaged (time t6), the torque increase amount is insufficient and the rotation speed of the engine 10 gradually decreases because the torque increase amount in output torque increase correction B is specified taking into account the cold start as described above.

[0033] When the rotation speed of the engine 10 further decreases (time t7), the torque increase amount further increases due to an increase in the insufficient rotation speed of the engine 10 relative to the target idle rotation speed, and the rotation speeds of the engine 10 and the motor 15 begin to rise, albeit gradually. At this time, when a short circuit abnormality of the inverter 17 is detected and three-phase ON control is executed (time t8), the ECU 23 executes the output torque increase correction A, the torque increase amount further increases, and the rotation speeds of the engine 10 and the motor 15 immediately rise to the target idle rotation speed. In this way, since the output torque increase correction A with a large torque increase amount is executed when a short circuit abnormality of the motor 15 is detected, the rotation speeds of the engine 10 and the motor 15 can be raised to the target rotation speeds early, and startability during evacuation running can be ensured.

[0034] In the example of Fig. 5, a case where a short circuit abnormality is detected after the start of the evacuation traveling and the three-phase ON control is executed is described as an example, but the present invention is not limited to this. For example, if a short circuit abnormality has already been detected and the three-phase ON control is executed at the start of the evacuation traveling, the output torque increase correction A is executed from the beginning of the start. In this case, when the K0 clutch 14 is in a slip state and the rotation speed of the engine 10 is reduced, the output torque of the engine 10 is corrected to be largely increased, so that the reduction in the rotation speed of the engine 10 is further suppressed.

[0035] Regarding the abnormality relating to the motor 15, a case where a short circuit abnormality occurs in the inverter 17 and the three-phase ON control is being executed has been described as an example, but the present invention is not limited to this.

[0036] In the above embodiment, the ECU 23 acquires the rotation speed of the engine 10 and the rotation speed of the motor 15 between step S2 and step S4, but this is not limited to this. For example, the ECU 23 may acquire the rotation speed of the engine 10 before step S1, or after step S1 and before step S2, or may constantly acquire the rotation speed of the engine 10 while executing each process.

[0037] In the above embodiment, a hybrid vehicle is controlled by a single ECU 23, but this is not limited to the above, and the above-mentioned control may be performed by multiple ECUs, such as an engine ECU that controls the engine 10, a motor ECU that controls the motor 15, and a clutch ECU that controls the K0 clutch 14.

[0038] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0039] 10 Engine 13 wheels 14 K0 clutch 15 Motor 23 ECU (control unit for hybrid vehicles) 25 Engine speed sensor

Claims

[Claim 1] A control device for a hybrid vehicle in which a motor is provided on a power transmission path between an engine and wheels, and a clutch is provided between the engine and the motor on the power transmission path, An acquisition unit that acquires a rotation speed of the engine; a first determination unit that determines whether the engine is running and whether the clutch is in either a slip state or an engaged state; a second determination unit that determines whether a rotation speed of the engine has decreased from a target idle rotation speed; a third determination unit that determines whether or not an abnormality exists in the motor; a correction unit that, when a positive determination is made by the first and second determination units, performs a correction to increase an output torque of the engine compared to a case where a negative determination is made by either the first or second determination unit, A control device for a hybrid vehicle, wherein the amount of increase in the output torque of the engine due to the correction is greater when the first, second, and third judgment units make positive judgments than when the first and second judgment units make positive judgments and the third judgment unit makes a negative judgment.

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