JP7626075B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device.

Vehicles are known in which an automatic transmission is arranged in part of the power transmission path between the electric motor and the drive wheels (see, for example, Patent Document 1).

JP 2014-073705 A

If the inertia phase stalls during a power-off upshift in an automatic transmission, it takes time for the inertia phase to end, resulting in a longer shift time. For this reason, it is possible to promote the inertia phase by increasing the engagement pressure of the engagement device that is controlled toward engagement during a power-off upshift. However, if the engagement pressure of the engagement device is increased, that engagement pressure may be transmitted to the output shaft of the automatic transmission, causing shift shock.

The present invention aims to provide a vehicle control device that prevents the lengthening of shift times and the occurrence of shift shocks during power-off upshifts.

The above object can be achieved by a control device for a vehicle including an electric motor and an automatic transmission that is arranged in a power transmission path between the electric motor and drive wheels and that changes gear stages by disengaging and engaging a predetermined one of a plurality of engagement devices, the control device including a determination unit that determines whether or not the progress of the inertia phase is stagnating during a power-off upshift shift by the automatic transmission, and a control unit that, when a positive determination is made by the determination unit, increases the engagement pressure of the engagement device that is controlled toward engagement during the power-off upshift shift and reduces the torque of the electric motor compared to when a negative determination is made by the determination unit.

The present invention provides a vehicle control device that prevents the lengthening of shift times and the occurrence of shift shocks during power-off upshifts.

FIG. 1 is a schematic diagram of a vehicle. FIG. 2 is a diagram showing the relationship between the gear stages established in the automatic transmission and the combinations of the operations of the engagement devices used therein. FIG. 3 is a flowchart showing an example of the shift delay suppression control executed by the ECU.

[General configuration of the vehicle]
FIG. 1 is a schematic diagram of a vehicle 1. In the vehicle 1, a K0 clutch 14, a motor 15, a torque converter 18, and an automatic transmission 19 are provided in this order in a power transmission path from an engine 10 to drive wheels 13. The vehicle 1 is a hybrid vehicle equipped with the engine 10 and the motor 15 as a driving power source. The engine 10 is, for example, a V-type 6-cylinder gasoline engine, but the number of cylinders is not limited thereto, and may be an in-line gasoline engine or a diesel engine. The motor 15 is an example of an electric motor. The K0 clutch 14, the motor 15, the torque converter 18, and the automatic transmission 19 are provided in a transmission unit 11. The transmission unit 11 and the left and right drive wheels 13 are drive-coupled via a differential 12.

The K0 clutch 14 is provided between the engine 10 and the motor 15 on the power transmission path. The K0 clutch 14 is switched between a released state, a slip state, and an engaged state depending on the supply of hydraulic pressure. In detail, when the K0 clutch 14 is in a released state, the hydraulic pressure supply causes the clutch 14 to enter a slip state or an engaged state, and the power transmission between the engine 10 and the motor 15 is connected. In addition, the K0 clutch 14 enters a released state in response to the stop of the hydraulic pressure supply, and the power transmission between the engine 10 and the motor 15 is interrupted. The slip state is a state in which the engagement element of the K0 clutch 14 on the engine 10 side and the engagement element on the motor 15 side are in sliding contact with each other with a predetermined rotational speed difference. The engaged state is a state in which both engagement elements of the K0 clutch 14 are connected and the engine 10 and the motor 15 have the same rotational speed. The released state is a state in which both engagement elements of the K0 clutch 14 are separated.

The motor 15 is connected to the battery 16 via the inverter 17. The motor 15 functions as a motor that generates driving force for the vehicle in response to power supplied from the battery 16, and also functions as a generator that generates power to charge the battery 16 in response to power transmission from the engine 10 and the drive wheels 13. The power exchanged between the motor 15 and the battery 16 is adjusted by the inverter 17.

The inverter 17 is controlled by the ECU 100 described below, and converts the DC voltage from the battery 16 to an AC voltage, or converts the AC voltage from the motor 15 to a DC voltage. In the case of power running in which the motor 15 outputs torque, the inverter 17 converts the DC voltage of the battery 16 to an AC voltage and adjusts the power supplied to the motor 15. In the case of regenerative running in which the motor 15 generates power, the inverter 17 converts the AC voltage from the motor 15 to a DC voltage and adjusts the power supplied to the battery 16.

The torque converter 18 is a fluid coupling with a torque amplification function. The automatic transmission 19 is a stepped transmission that switches the gear ratio in multiple stages by changing the gear stage. The automatic transmission 19 is provided between the motor 15 and the drive wheels 13 on the power transmission path. The motor 15 and the input shaft 19a of the automatic transmission 19 are connected via the torque converter 18. The output shaft 19b of the automatic transmission 19 is connected to the differential 12. The torque converter 18 is provided with a lock-up clutch 20 that receives hydraulic pressure, becomes engaged, and directly connects the motor 15 and the automatic transmission 19. Note that the torque converter 18 does not necessarily have to be provided.

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 the K0 clutch 14, the torque converter 18, the automatic transmission 19, and the lock-up clutch 20, as well as various hydraulic control valves for controlling the operating hydraulic pressures thereof.

The hybrid vehicle 1 is provided with an ECU (Electronic Control Unit) 100 as a control device for the vehicle. The ECU 100 is an electronic control unit that includes a calculation processing circuit that performs various calculation processes related to the vehicle's driving control, and a memory that stores control programs and data. The ECU 100 is an example of a vehicle control device, and functionally realizes a determination unit and a control unit, which will be described later.

The ECU 100 controls the operation of the engine 10 and the motor 15. Specifically, the ECU 100 controls the torque and rotation speed of the engine 10 by controlling the throttle opening, ignition timing, and fuel injection amount of the engine 10. The ECU 100 controls the rotation speed and torque of the motor 15 by controlling the inverter 17 to adjust the amount of power exchanged between the motor 15 and the battery 16. The ECU 100 also 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 100 receives signals from an ignition switch 71, a crank angle sensor 72, and motor rotation speed sensors 73, 74, and 75. The crank angle sensor 72 detects the rotation speed of the crankshaft of the engine 10. The motor rotation speed sensor 73 detects the rotation speed of the output shaft of the motor 15. The input shaft rotation speed sensor 74 detects the rotation speed of the input shaft 19a. The output shaft rotation speed sensor 75 detects the rotation speed of the output shaft 19b.

The ECU 100 runs the hybrid vehicle in either the motor mode or the hybrid mode. In the motor mode, the ECU 100 releases the K0 clutch 14 and runs the vehicle using the power of the motor 15. In the hybrid mode, the ECU 100 switches the K0 clutch 14 to an engaged state and runs the vehicle using at least the power of the engine 10. The hybrid mode includes a mode in which the motor 15 is operated in regenerative mode and runs using only the power of the engine 10, and a mode in which the motor 15 is operated in power running mode and runs using both the engine 10 and the motor 15 as a running power source. The running mode is switched based on the required driving force of the vehicle calculated from the vehicle speed and accelerator opening, the charge state of the battery 16, etc.

The automatic transmission 19 has one or more planetary gear sets and multiple engagement devices, and multiple gear stages are alternatively established by the engagement devices. The automatic transmission 19 performs so-called clutch-to-clutch shifting, in which gear shifting is performed by switching between engagement and disengagement of the engagement devices. The engagement devices are hydraulic engagement devices that transmit rotation and torque between an input shaft 19a that receives power from the engine 10 and an output shaft 19b that transmits power to the drive wheels 13.

The engagement devices are clutches C and brakes B that are engaged or released when the torque capacity, i.e., the engagement pressure, changes through pressure adjustment by a solenoid valve or the like in the hydraulic control mechanism 22. The engagement pressure is determined by the friction coefficient of the friction material of the engagement device and the hydraulic pressure pressing the friction plate. In order to transmit torque between the input shaft 19a and the output shaft 19b without causing a difference in rotational speed, an engagement pressure is required that provides the transmission torque that each engagement device needs to bear for that torque.

2 is a diagram showing the relationship between the gear stages established by the automatic transmission 19 and the combination of the operation of the engagement devices used therein. "Circle" indicates an engaged state, and "blank" indicates a released state. The gear stages in the automatic transmission 19 are each established in eight forward gear stages according to the driver's accelerator operation, vehicle speed V, etc., by controlling the engagement and release of the clutches C (C1, C2, C3, C4) and the brakes B (B1, B2). In addition, when there is no need to distinguish between the clutches C and the brakes B, which are both engagement devices, they may be collectively referred to as "clutches" without any particular distinction. In addition, the engagement device that forms the high gear stage is controlled toward engagement during upshifting from the low gear stage to the high gear stage (hereinafter referred to as the engagement side clutch), and is controlled toward release during downshifting from the high gear stage to the low gear stage (hereinafter referred to as the release side clutch). The engagement device that forms the low gear stage corresponds to the release side clutch during upshifting, and corresponds to the engagement side clutch during downshifting.

[Gear shift delay suppression control]
3 is a flow chart showing an example of the shift delay suppression control executed by the ECU 100. This control is repeatedly executed at a predetermined cycle while the ignition is on. The ECU 100 judges whether or not the automatic transmission 19 is performing a power-off upshift (step S1). The power-off upshift is a shift in which an upshift occurs as the accelerator operation amount decreases. If the answer is No in step S1, this control ends.

If the answer is Yes in step S1, the ECU 100 determines whether or not the inertia phase is in progress (step S2). The inertia phase is a period during which the input shaft 19a changes to the synchronous rotation speed of the gear stage after the shift. Specifically, if the differential rotation speed between the current rotation speed of the input shaft 19a and the rotation speed of the input shaft 19a after the shift is outside a predetermined range, the inertia phase is determined to be in progress. If this differential rotation speed is within a predetermined range, the inertia phase is determined to have ended. The rotation speed of the input shaft 19a after the shift is calculated as being synchronized with the rotation speed of the output shaft 19b after the shift, and specifically, it is calculated by multiplying the rotation speed of the output shaft 19b detected by the output shaft rotation speed sensor 75 by the gear ratio (gear ratio) of the gear stage after the shift.

If the answer is Yes in step S2, it is determined whether the inertia phase is stalled (step S3). Specifically, if the rate of change in the rotation speed of the input shaft 19a detected by the input shaft rotation speed sensor 74 is within a predetermined range, it is determined that the rotation speed of the input shaft 19a does not decrease and the inertia phase is stalled. If the rate of change in the rotation speed of the input shaft 19a is outside the predetermined range, it is determined that the rotation speed of the input shaft 19a is decreasing and the inertia phase is progressing. Note that such stalling of the decrease in the rotation speed of the input shaft 19a tends to occur easily when traveling in hybrid mode with the K0 clutch 14 engaged. This is because the rotation speed of the input shaft 19a is unlikely to decrease with only the friction torque of the engine 10 while traveling in hybrid mode. Step S3 is an example of a process executed by the determination unit.

If the answer is Yes in step S3, the ECU 100 determines whether a motor torque down process is being executed to reduce the torque of the motor 15 (step S4). If the answer is No in step S4, the ECU 100 determines whether the stagnation time of the inertia phase is equal to or longer than a predetermined time (step S5). If the answer is No in step S5, the control ends.

If step S5 is Yes, the ECU 100 increases the engagement pressure of the on-coming clutch (step S6) and executes the motor torque down process (step S7). The increase in the engagement pressure of the on-coming clutch can be achieved by increasing the hydraulic command value supplied to the on-coming clutch by a predetermined value from the normal value. The motor torque down process can be achieved by reducing the torque required for the motor 15 by a predetermined amount. By increasing the engagement pressure of the on-coming clutch, the progress of the inertia phase can be promoted and the lengthening of the shift time can be suppressed. In addition, by reducing the torque of the motor 15, the torque transmitted to the output shaft 19b can be reduced while promoting the reduction in the rotation speed of the input shaft 19a, and the occurrence of shift shock can be suppressed. Steps S6 and S7 are an example of the process executed by the control unit.

Note that there is a time lag between when the hydraulic pressure command value for the on-coming clutch increases and when the hydraulic pressure actually supplied to the on-coming clutch increases. Taking this time lag into consideration, step S7 may be executed with a time lag after step S6 is executed. Also, when the motor 15 is in regenerative operation while traveling in hybrid mode, the inertia phase may be promoted by increasing the regenerative torque of the motor 15 through motor torque down processing. Also, when traveling in hybrid mode, if the engine 10 speed falls below the idle speed as a result of the motor torque down processing, the motor torque down processing may be stopped.

If the answer is Yes in step S4, the ECU 100 increases the torque reduction amount of the motor 15 by a predetermined amount (step S8). This further promotes the reduction in the rotation speed of the input shaft 19a while suppressing the torque transmitted to the output shaft 19b.

If the answer is No in step S3, the ECU 100 determines whether the motor torque down process is being executed (step S9). If the answer is No in step S9, the control ends. If the answer is Yes in step S9, the ECU 100 maintains the torque down amount of the motor 15 (step S10). This prevents the torque of the motor 15 from being reduced more than necessary, even after the stagnation of the inertia phase progress is resolved, and thus prevents the rotational speed of the input shaft 19a from being unnecessarily reduced. Note that the torque down amount of the motor 15 may be reduced in step S10.

If the answer is No in step S2, i.e., if the inertia phase ends and the torque phase starts, the ECU 100 determines whether the motor torque down process is being executed (step S11). If the answer is No in step S11, this control ends. If the answer is Yes in step S11, the ECU 100 gradually reduces the torque down amount of the motor 15 (step S12). In this way, when the inertia phase ends, the torque of the motor 15 can be returned to the normal value, and the variation in the deceleration rate of the vehicle 1 can be suppressed.

In the above embodiment, the execution condition for steps S6 and S7 requires that step S5 be judged as Yes, but this is not limited to this. For example, steps S6 and S7 may be executed without executing step S5. This can promote the progression of the inertia phase early. Also, in the above embodiment, the execution condition for steps S6 and S7 requires that step S4 be judged as No, but this is not limited to this. For example, motor torque down processing may be executed without executing steps S4 and S8. In this case, if the motor torque down processing is already being executed, the motor torque down processing continues at a constant torque down amount.

In the above embodiment, the vehicle 1 is controlled by a single ECU 100, but this is not limited to the above. For example, the above-mentioned control may be performed by multiple ECUs, such as an engine ECU that controls the engine 10 and a motor ECU that controls the motor 15.

The vehicle 1 in the above embodiment is a hybrid vehicle, but is not limited to this. For example, it may be an electric vehicle equipped with only a motor as a driving power source.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims.

1 Vehicle 10 Engine 13 Drive wheel 14 K0 clutch 15 Motor (electric motor)
19 Automatic transmission 19a Input shaft 19b Output shaft 100 ECU (determination unit, control unit)

Claims (1)

A control device for a vehicle including an electric motor and an automatic transmission that is disposed in a power transmission path between the electric motor and a drive wheel and changes a gear stage by disengaging and engaging a predetermined engagement device among a plurality of engagement devices,
a determination unit that determines whether or not progress of an inertia phase is stagnating during a power-off upshift by the automatic transmission;
A control device for a vehicle comprising: a control unit that, when a positive judgment is made by the judgment unit, increases the engagement pressure of the engagement device that is controlled toward engagement during the power-off upshift gear shift and reduces the torque of the electric motor compared to when a negative judgment is made by the judgment unit.

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