JP2022132871A - Control device of hybrid vehicle - Google Patents

Abstract

To provide a control device of a hybrid vehicle improved in low temperature startability.SOLUTION: A control device of a hybrid vehicle is provided with a motor on a power transmission path between an engine and wheels, is provided with a clutch between the engine and the motor on the power transmission path and is provided with an automatic transmission between the motor on the power transmission path and the wheels. The control device of a hybrid vehicle is equipped with a determining portion that determines whether or not the engine and the motor are being driven and the clutch is in an engaged state, an obtaining portion that obtains the temperature of lubricant in at least one of the motor, the clutch, and the automatic transmission when the determining portion makes a positive determination, and a correcting portion that, when the temperature of the lubricant is less than a threshold value, corrects so as to increase the output torque of at least one of the engine and the motor as compared with a case where the temperature of the lubricant is the threshold or more.SELECTED DRAWING: Figure 3

Description

The present invention relates to a hybrid vehicle control device.

A motor is provided on the power transmission path between the engine and the wheels, a clutch is provided between the engine and the motor on the power transmission path, and an automatic transmission is provided between the motor and the wheels on the power transmission path. A hybrid vehicle is known (see, for example, Patent Document 1).

JP 2012-091571 A

When the hybrid vehicle is started, the clutch is engaged after the engine and the motor are started, the engine and the motor are connected, and the rotation speeds of the engine and the motor are maintained at, for example, the target idle rotation speed. Here, during low-temperature starting, the temperature of lubricating oil for the clutch, motor, and automatic transmission decreases, the viscosity increases, and the friction torque increases. Therefore, when the engine and motor are started and the clutch is engaged at low temperature start, the increase in friction torque cannot be compensated for by the output torque of the engine and motor, and the rotational speed of the engine and motor increases. There is a possibility that the idling speed will be lower than the target idling speed. In this way, the low temperature startability may be degraded.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a control device for a hybrid vehicle with improved low-temperature startability.

A motor is provided on a power transmission path between an engine and wheels, a clutch is provided between the engine and the motor on the power transmission path, and the motor and the wheels are provided on the power transmission path. and a determination unit that determines whether the engine and the motor are in operation and the clutch is in an engaged state, and a positive determination by the determination unit an obtaining unit that obtains the temperature of at least one of the lubricating oil of the motor, the clutch, and the automatic transmission when a determination is made; and a correction unit that corrects the output torque of at least one of the engine and the motor to increase more than the threshold value or more.

According to the present invention, it is possible to provide a control device for a hybrid vehicle with improved low-temperature startability.

FIG. 1 is a schematic configuration diagram of a hybrid vehicle. FIG. 2 is a timing chart showing transitions in engine speed, motor speed, and hydraulic pressure supplied to the K0 clutch in a comparative example. FIG. 3 is a flowchart showing an example of output torque increase control executed by the ECU. FIG. 4 is an example of a map that defines torque increase amounts according to oil temperature. FIG. 5 is a timing chart showing changes in engine speed, motor speed, oil pressure supplied to the K0 clutch, and torque increase amount in this embodiment.

[Schematic configuration of hybrid vehicle]
FIG. 1 is a schematic configuration diagram of a hybrid vehicle. The hybrid vehicle is equipped with an engine 10 and a motor 15 as driving sources for running. 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 .

The transmission unit 11 is provided with a K0 clutch 14 and a motor 15 . A motor 15 is installed in the transmission unit 11 so as to be positioned on a power transmission path from the engine 10 to the wheels 13 . K0 clutch 14 is provided between engine 10 and motor 15 on the same power transmission path. The K0 clutch 14 is supplied with hydraulic pressure and becomes engaged to connect power transmission between the engine 10 and the motor 15 . The K0 clutch 14 is opened in response to the stoppage of hydraulic pressure supply, and cuts off power transmission between the engine 10 and the motor 15 .

Motor 15 is connected to vehicle battery 16 via inverter 17 . The motor 15 functions as a motor that generates driving force for the vehicle in response to power supply from the vehicle-mounted battery 16, and also generates electric power to charge the vehicle-mounted battery 16 in accordance with power transmission from the engine 10 and the wheels 13. It also functions as a machine. Electric power exchanged between the motor 15 and the vehicle-mounted battery 16 is regulated by the inverter 17 .

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 gear stages. In the transmission unit 11, the automatic transmission 19 is provided between the motor 15 and the wheels 13 on the power transmission path. A motor 15 and an automatic transmission 19 are connected via a torque converter 18 . The torque converter 18 is provided with a lockup clutch 20 that is engaged by being supplied with hydraulic pressure to directly connect the motor 15 and the automatic transmission 19 .

Furthermore, the transmission unit 11 is provided with an oil pump 21 and a hydraulic control mechanism 22 . 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 lockup clutch 20 via the hydraulic control mechanism 22, respectively. The hydraulic control mechanism 22 includes hydraulic circuits for the K0 clutch 14, the torque converter 18, the automatic transmission 19, and the lockup clutch 20, and various hydraulic control valves for controlling the operating hydraulic pressures of these circuits. It is

The hybrid vehicle is provided with an ECU (Electronic Control Unit) 23 as a control device for the vehicle. The ECU 23 is an electronic control unit that includes an arithmetic processing circuit that performs various kinds of arithmetic processing related to vehicle travel control, and a memory that stores control programs and data. The ECU 23 is an example of a hybrid vehicle control device, and functionally implements a determination unit, an acquisition unit, and a correction unit, which will be described later in detail.

The ECU 23 controls driving of the engine 10 and the motor 15 . For example, the ECU 23 performs torque control of the engine 10 by controlling the throttle opening, ignition timing, and fuel injection amount of the engine 10 . The ECU 23 also controls the inverter 17 to adjust the amount of electric power exchanged between the motor 15 and the vehicle-mounted battery 16 , thereby performing torque control of the motor 15 . Furthermore, the ECU 23 controls the driving of the K0 clutch 14 , the lockup clutch 20 and the automatic transmission 19 through the control of the hydraulic control mechanism 22 . The ECU 23 includes a crank angle sensor 25 that detects the rotation speed of the crankshaft of the engine 10, a hydraulic pressure sensor 26 that detects the hydraulic pressure supplied to the K0 clutch 14, and the temperature of lubricating oil of the automatic transmission 19 (hereinafter referred to as oil temperature and ), and other detection signals such as the accelerator pedal opening, which is the amount of depression of the accelerator pedal by the driver. The ECU 23 can grasp whether the K0 clutch 14 is in the released state or in the engaged state based on the output value of the oil pressure sensor 26 .

[Low temperature startability in comparative example]
Next, low-temperature startability of a hybrid vehicle in a comparative example will be described. FIG. 2 is a timing chart showing transitions of the rotational speed [rpm] of the engine 10, the rotational speed [rpm] of the motor 15, and the hydraulic pressure [Pa] supplied to the K0 clutch 14 in the comparative example. When the ignition of the hybrid vehicle is turned on, the starter 24 is driven to start the engine 10 (time t1), and then the motor 15 is started (time t2). When the hydraulic pressure to the K0 clutch 14 in the released state increases (time t3) and the K0 clutch 14 is engaged (time t4), the engine 10 and the motor 15 are connected, and the rotation speed of the engine 10 and the rotation speed of the motor 15 match the number of revolutions. Here, for example, when the outside temperature is 5° C. to 30° C. at the time of starting under normal temperature environment, the rotation speeds of the engine 10 and the motor 15 after the K0 clutch 14 is engaged are maintained at the target idle rotation speed.

However, at the time of starting in a low-temperature environment where the outside temperature is less than 5° C., for example, the temperature of the lubricating oil used in the K0 clutch 14, the motor 15, and the automatic transmission 19 is also low, so the viscosity is high. Torque is increasing. Therefore, at the time of cold start, after the K0 clutch 14 is engaged, the increase in friction torque cannot be compensated for by the output torque of the engine 10 and the motor 15, and the rotation speed of the engine and the motor is reduced from the target idle rotation speed. may decrease. As a result, the low-temperature startability may deteriorate, for example, the engine 10 may stall. Therefore, the ECU 23 of this embodiment executes the following output torque increase control.

[Output torque increase control]
FIG. 3 is a flow chart showing an example of the output torque increase control executed by the ECU 23. As shown in FIG. This control is repeatedly executed while the ignition of the hybrid vehicle is on. First, the ECU 23 determines whether the engine 10 and the motor 15 are being driven (step S1). Next, the ECU 23 determines whether or not the K0 clutch 14 is engaged based on the detected value of the oil pressure sensor 26 (step S2). The processing of steps S1 and S2 is an example of processing executed by the determination unit. If No in either step S1 or S2, this control is terminated.

If Yes in steps S1 and S2, the ECU 23 acquires the engine speed and oil temperature based on the detected values of the crank angle sensor 25 and the oil temperature sensor 27 (step S3). As described above, when the K0 clutch 14 is engaged, the rotation speeds of the engine 10 and the motor 15 match.

Next, the ECU 23 determines whether or not the oil temperature is less than the temperature α (step S4). The temperature α is set to a temperature at which the viscosity of the lubricating oil increases and the friction torque of the K0 clutch 14, the motor 15, and the automatic transmission 19 begins to increase. The temperature α is an example of a threshold. If No in step S4, this control ends.

If Yes in step S4, the ECU 23 executes output torque increase correction (step S5). The output torque increase correction increases the total output torque of the engine 10 and the motor 15 by the amount of torque increase calculated based on the map of FIG. Correction. Therefore, only the output torque of either the engine 10 or the motor 15 may be increased by the calculated torque increase amount. Further, the output torque of each of the engine 10 and the motor 15 may be increased so that the sum of the increase in the output torque of the engine 10 and the increase in the output torque of the motor 15 is equal to the calculated torque increase amount. good. The increase in the output torque of the engine 10 can be realized by controlling the throttle opening, ignition timing, and fuel injection amount. An increase in the output torque of the motor 15 can be realized by controlling the inverter 17 to increase the electric power supplied from the vehicle-mounted battery 16 to the motor 15 . The processing of step S5 is an example of processing executed by the correction unit.

FIG. 4 is an example of a map that defines torque increase amounts according to oil temperature. In FIG. 4, the horizontal axis indicates the oil temperature [° C.] and the vertical axis indicates the torque increase amount [N·m]. Further, FIG. 4 shows, as an example, the case where the engine 10 and the motor 15 rotate at high speed and low speed.

As shown in FIG. 4, regardless of whether the engine 10 and the motor 15 rotate at a high speed or a low speed, the torque increase amount increases as the oil temperature decreases below the temperature α. This is because when the oil temperature drops below the temperature α, the viscosity of the lubricating oil increases and the friction torque also increases. When the oil temperature drops below the temperature (-β), the torque increase amount becomes constant. This is because when the oil temperature drops below the temperature (-β), the viscosity of the lubricating oil becomes substantially constant and the friction torque also becomes substantially constant. Also, the higher the rotational speeds of the engine 10 and the motor 15, the greater the torque increase amount. This is because the friction torque increases as the rotation speeds of the engine 10 and the motor 15 increase. Thus, the torque increase amount defined by the map of FIG. 4 corresponds to the friction torque increase amount according to the oil temperature. FIG. 4 shows only two cases of high rotation and low rotation of the engine 10 and motor 15; , and is defined such that the higher the rotational speeds of the engine 10 and the motor 15, the greater the torque increase amount.

[Low temperature startability of the present embodiment]
Next, low-temperature startability of the hybrid vehicle in this embodiment will be described. FIG. 5 is a timing chart showing changes in the number of rotations of the engine 10, the number of rotations of the motor 15, the hydraulic pressure supplied to the K0 clutch 14, and the amount of torque increase in this embodiment. FIG. 5 corresponds to FIG. 2, and since it is the same as FIG. 2 up to time t4, redundant description will be omitted. At time t4 when it is determined that the K0 clutch 14 is engaged, the output torque increase correction is performed, thereby maintaining the rotation speeds of the engine 10 and the motor 15 at the target idle rotation speed. As a result, stalling of the engine 10 is suppressed and low-temperature startability is improved.

After time t4 in FIG. 5, the torque increase amount gradually decreases. This is because the oil temperature gradually rises due to the heat of the engine 10 and the motor 15, and the torque increase amount defined by the map in FIG. 4 gradually decreases. As described above, the friction torque decreases due to the increase in the oil temperature, but the amount of increase in torque decreases as the friction torque decreases, so the output torque can be increased just enough.

The rotation speeds of the engine 10 and the motor 15 increase according to the amount of operation of the accelerator pedal. Perform growth correction.

In the above embodiment, whether or not to execute the output torque increase correction is determined based on the temperature of the lubricating oil of the automatic transmission 19. should be used. This is because the temperatures of these lubricating oils can be regarded as substantially the same.

It is also conceivable to use the temperature of the cooling water of the engine 10 instead of the temperature of the lubricating oil so that the torque increase amount increases as the temperature of the cooling water decreases. However, there is a time lag between when the engine 10 starts and the temperature of the cooling water begins to rise and the temperature of the lubricating oil in the automatic transmission 19 and the like begins to rise due to the heat of the engine 10 and the like. Therefore, for example, even if the temperature of the cooling water rises to some extent, it is conceivable that the temperature of the lubricating oil is still low and the friction torque is large. Therefore, by using the temperature of the lubricating oil, the torque increase amount corresponding to the magnitude of the friction torque can be accurately calculated, and the output torque can be increased just enough.

In the present embodiment, the case where the hybrid vehicle is controlled by the single ECU 23 has been exemplified, but the present invention is not limited to this. For example, the engine ECU controlling the engine 10, the motor ECU controlling the motor 15, and the K0 clutch 14 are controlled. The control described above may be executed by a plurality of ECUs such as the clutch ECU.

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 can be made within the scope of the gist of the present invention described in the scope of claims. Change is possible.

REFERENCE SIGNS LIST 10 engine 13 wheel 14 K0 clutch 15 motor 19 automatic transmission 23 ECU (control device for internal combustion engine)
27 oil temperature sensor

Claims (1)

A motor is provided on a power transmission path between an engine and wheels, a clutch is provided between the engine and the motor on the power transmission path, and a clutch is provided between the motor on the power transmission path and the wheels. In a hybrid vehicle control device provided with an automatic transmission,
a determination unit that determines whether the engine and the motor are in operation and the clutch is in an engaged state;
an obtaining unit that obtains the temperature of lubricating oil for at least one of the motor, the clutch, and the automatic transmission when the determination unit makes an affirmative determination;
a correction unit that corrects so that the output torque of at least one of the engine and the motor increases when the temperature of the lubricating oil is less than the threshold value than when the temperature of the lubricating oil is equal to or higher than the threshold value. Vehicle controller.

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