Vehicle control device

Abstract

To provide a control device for a vehicle, capable of suppressing the prolongation of a shift time and the occurrence of a shift shock during power-off upshift gear change.SOLUTION: There is provided a control device for a vehicle including an electric motor and an automatic transmission which is arranged in a power transmission path between the electric motor and a drive wheel, and which changes a gear stage by disengagement or engagement of a prescribed engagement device of a plurality of engagement devices. The control device includes: a determination section which determines whether or not the progress of an inertia phase is stagnated during power-off upshift gear change by the automatic transmission; and a control section which, in a case where an affirmative determination is made by the determination section, increases the engagement pressure of the engagement device controlled toward engagement in the power-off upshift gear change and decreases the torque of the electric motor, as compared to a case where a negative determination is made by the determination section.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] 2. Description of the Related Art Vehicles are known in which an automatic transmission is disposed in a portion of a power transmission path between an electric motor and drive wheels (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-073705 A Summary of the Invention [Problem to be solved by the invention]

[0004] 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 conceivable to promote the inertia phase by increasing the engagement pressure of an engagement device that is controlled toward engagement during a power-off upshift. However, if the engagement pressure of an engagement device is increased, the engagement pressure may be transmitted to the output shaft of the automatic transmission, causing a shift shock.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a vehicle control device that suppresses the lengthening of shift time and the occurrence of shift shock during power-off upshift shifting. [Means for solving the problem]

[0006] 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 specific one of a plurality of engagement devices, the control device including a judgment unit that judges whether or not 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 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 shift and reduces the torque of the electric motor compared to when a negative judgment is made by the judgment unit. Effect of the Invention

[0007] According to the present invention, it is possible to provide a vehicle control device that suppresses the lengthening of gear shift time and the occurrence of gear shift shock during power-off upshifting. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a vehicle. [Diagram 2] 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. [Diagram 3] FIG. 3 is a flowchart showing an example of the shift delay suppression control executed by the ECU. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Vehicle outline] 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 V6 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 drivingly connected via a differential 12.

[0010] 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 to any one of a released state, a slip state, and an engaged state according to the supply of hydraulic pressure. In detail, when the K0 clutch 14 is in the released state, the K0 clutch 14 is switched to a slip state or an engaged state by the supply of hydraulic pressure, and the power transmission between the engine 10 and the motor 15 is connected. In addition, the K0 clutch 14 is switched to a released state according 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.

[0011] The motor 15 is connected to the 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 battery 16, and also functions as a generator that generates electric power to charge the battery 16 in response to power transmission from the engine 10 and the drive wheels 13. The electric power exchanged between the motor 15 and the battery 16 is adjusted by the inverter 17.

[0012] The inverter 17 is controlled by the ECU 100 described later, and converts the DC voltage from the battery 16 into an AC voltage, or converts the AC voltage from the motor 15 into a DC voltage. In the case of powering operation in which the motor 15 outputs torque, the inverter 17 converts the DC voltage of the battery 16 into an AC voltage and adjusts the power supplied to the motor 15. In the case of regenerative operation in which the motor 15 generates power, the inverter 17 converts the AC voltage from the motor 15 into a DC voltage and adjusts the power supplied to the battery 16.

[0013] The torque converter 18 is a fluid coupling having a torque amplifying function. The automatic transmission 19 is a stepped transmission that changes 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 an 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 is supplied with hydraulic pressure and is in an engaged state to directly connect the motor 15 and the automatic transmission 19. The torque converter 18 is not necessarily provided.

[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 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 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 100 is an example of a control device for the vehicle, and functionally realizes a determination unit and a control unit, which will be described later.

[0016] 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.

[0017] 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 a crankshaft of the engine 10. The motor rotation speed sensor 73 detects the rotation speed of an 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.

[0018] The ECU 100 runs the hybrid vehicle in either a motor mode or a 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 a regenerative manner and runs using only the power of the engine 10, and a mode in which the motor 15 is operated in a power running manner 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 state of charge of the battery 16, and the like.

[0019] The automatic transmission 19 has one or more planetary gear sets and multiple engagement devices, and multiple gear stages are selectively 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.

[0020] The engaging devices are clutches C and brakes B that are engaged or released when the torque capacity, i.e., the engaging pressure, changes through pressure adjustment by a solenoid valve or the like in the hydraulic control mechanism 22. The engaging pressure is determined by the friction coefficient of the friction material of the engaging 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 engaging pressure is required that provides the amount of transmission torque that each engaging device needs to bear for that torque.

[0021] FIG. 2 is a diagram showing the relationship between the gear stages established in 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. As for the gear stages in the automatic transmission 19, each of the eight forward gear stages is established according to the driver's accelerator operation, the vehicle speed V, etc., by the respective engagement and release control 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.

[0022] [Gear shift delay suppression control] 3 is a flowchart showing an example of the shift delay suppression control executed by the ECU 100. This control is repeatedly executed at predetermined intervals while the ignition is on. The ECU 100 determines whether or not the automatic transmission 19 is performing a power-off upshift (step S1). A 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.

[0023] If the answer is Yes in step S1, the ECU 100 judges 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 judged to be in progress. If the differential rotation speed is within a predetermined range, the inertia phase is judged 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, the rotation speed 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.

[0024] If the answer is Yes in step S2, it is determined whether the inertia phase is stalled (step S3). Specifically, when 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. When 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 decreases 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 during running in the hybrid mode with the K0 clutch 14 engaged. This is because the rotation speed of the input shaft 19a is unlikely to decrease only by the friction torque of the engine 10 during running in the hybrid mode. Step S3 is an example of a process executed by the determination unit.

[0025] If the answer is Yes in step S3, the ECU 100 determines whether or not 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 or not 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, this control ends.

[0026] If the answer is Yes in step S5, the ECU 100 increases the engagement pressure of the on-coming clutch (step S6) and executes a motor torque down process (step S7). The increase in the engagement pressure of the on-coming clutch can be realized 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 realized 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 gear shift time can be suppressed. Furthermore, 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, thereby suppressing the occurrence of gear shift shock. Steps S6 and S7 are an example of the process executed by the control unit.

[0027] It should be noted 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 the hybrid mode, the regenerative torque of the motor 15 may be increased by the motor torque down process to promote the progression of the inertia phase. Also, when traveling in the hybrid mode, if the rotation speed of the engine 10 becomes equal to or lower than the idle rotation speed as a result of the motor torque down process, the motor torque down process may be stopped.

[0028] If the answer is Yes in step S4, the ECU 100 increases the torque-down amount of the motor 15 by a predetermined amount (step S8). This makes it possible to further promote the reduction in the rotation speed of the input shaft 19a while suppressing the torque transmitted to the output shaft 19b.

[0029] If the answer is No in step S3, the ECU 100 determines whether or not the motor torque down process is being executed (step S9). If the answer is No in step S9, this 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 makes it possible to prevent the torque of the motor 15 from being reduced more than necessary, even after the stagnation of the inertia phase progress is resolved, and to prevent the rotation 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.

[0030] If the answer is No in step S2, that is, if the inertia phase ends and the torque phase starts, the ECU 100 determines whether or not 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 restored to the normal value, and the variation in the deceleration rate of the vehicle 1 can be suppressed.

[0031] In the above embodiment, the execution condition for steps S6 and S7 requires that step S5 be determined as Yes, but this is not limited thereto. For example, steps S6 and S7 may be executed without executing step S5. This can promote the progress of the inertia phase at an early stage. Furthermore, in the above embodiment, the execution condition for steps S6 and S7 requires that step S4 be determined as No, but this is not limited thereto. For example, the motor torque down process may be executed without executing steps S4 and S8. In this case, if the motor torque down process is already being executed, the motor torque down process is continued at a constant torque down amount.

[0032] In the above embodiment, an example was given of a case where the vehicle 1 is controlled by a single ECU 100, but this is not limited to this, and 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.

[0033] The vehicle 1 in the above embodiment is a hybrid vehicle, but is not limited to this, and may be, for example, an electric vehicle equipped with only a motor as a driving power source.

[0034] 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]

[0035] 1 vehicle 10 Engine 13 Drive wheels 14 K0 clutch 15 Motor (electric motor) 19 Automatic transmission 19a Input shaft 19b Output shaft 100 ECU (judgment unit, control unit)

Claims

[Claim 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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