Hybrid vehicles

Abstract

To suppress a sense of the incongruity of a driver.SOLUTION: A hybrid vehicle, which includes a control device for controlling an engine, an automatic transmission and a motor so that a vehicle travels while switching between a hybrid travel mode of traveling using power from an engine with a clutch as an engaged state and an electric travel mode of traveling without using power from the engine with the clutch as a release state, calculates a creep torque estimation value as an estimation value of a creep torque output to an input shaft of the automatic transmission when it is assumed that the engine is operated on the basis of a cooling water temperature of the engine during traveling in the electric travel mode with vehicle speed equal to or lower than predetermined vehicle speed, and controls the motor so that the same torque as the creep torque estimation value is output from the motor.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, a hybrid vehicle of this type has been proposed that includes an engine, a continuously variable transmission connected via a clutch to a drive shaft connected to the wheels, a torque converter connected to the engine and the continuously variable transmission, and a motor connected to the drive shaft (see, for example, Patent Document 1).In this hybrid vehicle, when switching from an electric drive mode in which the clutch is released and the vehicle travels without using power from the engine to a hybrid drive mode in which the clutch is engaged and the vehicle travels using power from the engine, engagement of the clutch begins when the rotation speed of the turbine runner of the torque converter after engaging the clutch is equal to or higher than the rotation speed of the engine, thereby suppressing shock associated with clutch engagement. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-27965 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the hybrid vehicle described above, although the shock caused by clutch engagement is suppressed, it is unable to suppress the creep torque and changes in the rotation speed of the transmission input shaft when switching from electric driving mode to hybrid driving mode, which can cause discomfort to the driver.

[0005] The hybrid vehicle of the present invention aims to suppress the sense of discomfort felt by the driver. [Means for solving the problem]

[0006] A first hybrid vehicle of the present invention is a hybrid vehicle comprising an engine, a motor connected to an output shaft of the engine at least via a clutch, an automatic transmission whose output shaft is connected to wheels, a torque converter arranged between the clutch and an input shaft of the automatic transmission, and a control device that controls the engine, the automatic transmission, and the motor to run by switching between a hybrid driving mode in which the clutch is engaged and the vehicle runs using power from the engine, and an electric driving mode in which the clutch is released and the vehicle runs without using power from the engine, wherein the control device, while running in the electric driving mode at a vehicle speed below a predetermined vehicle speed, calculates a creep torque estimate value as an estimate of creep torque that will be output to the input shaft of the automatic transmission when it is assumed that the engine is operating based on the engine coolant temperature, and controls the motor so that a torque equal to the creep torque estimate value is output from the motor.

[0007] A second hybrid vehicle of the present invention is a hybrid vehicle comprising an engine, a motor connected to the output shaft of the engine via a clutch, an automatic transmission whose output shaft is connected to wheels, a torque converter having a lock-up clutch and arranged between the motor and the input shaft of the automatic transmission, and a control device that controls the engine, the automatic transmission, the clutch, the motor, and the lock-up clutch so as to switch between a hybrid driving mode in which the clutch is engaged and the vehicle runs using power from the engine, and an electric driving mode in which the clutch is released and the vehicle runs without using power from the engine, and the control device is configured such that when the lock-up clutch is released while the vehicle is running in the electric driving mode at a vehicle speed equal to or lower than a predetermined vehicle speed, the control device calculates an estimated rotation speed as an estimate of the engine rotation speed when the engine is operating based on the engine coolant temperature, and controls the automatic transmission so that the motor rotation speed is equal to the estimated rotation speed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the outline of the configuration of a hybrid vehicle 20. [Figure 2] 10 is a flowchart illustrating an example of a target value setting routine. [Figure 3] FIG. 10 is a diagram showing the outline of the configuration of a hybrid vehicle 120 according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Next, a mode for carrying out the present invention will be described using examples. [Example]

[0010] FIG. 1 is a schematic diagram illustrating the configuration of a hybrid vehicle 20 according to one embodiment of the present invention. As shown in FIG. 1 , the hybrid vehicle 20 of the embodiment includes an engine 22, a motor 30 having a rotating shaft 31 connected to a crankshaft 23 of the engine 22 via a clutch K0 and connected to an input shaft 41 of an automatic transmission 40, an inverter 32 connected to a battery 60 and driving the motor 30, the clutch K0 configured as, for example, a hydraulically driven friction clutch that connects and disconnects the crankshaft 23 and the rotating shaft 31, the automatic transmission 40, and an electronic control unit (hereinafter referred to as "ECU") 70. The automatic transmission 40 includes a torque converter 43 and an automatic transmission 45. The torque converter 43 is configured as a typical fluid transmission and includes a hydraulically driven lock-up clutch LU that connects and disconnects an input-side pump impeller connected to the rotating shaft 31 of the motor 30 and an output-side turbine runner connected to a transmission input shaft 44. The automatic transmission 45 has a plurality of forward and reverse gears and transmits power between the transmission input shaft 44 and the output shaft 42. The hydraulic pressure of the hydraulic oil supplied to the clutch K0, the automatic transmission 45, and the lock-up clutch LU is adjusted by a hydraulic control device (not shown). The engine 22, the inverter 32, and the hydraulic control device are controlled by an ECU 70. The ECU 70 is configured as a microcomputer having a CPU and input / output ports (not shown). The ECU 70 receives signals from various sensors via input ports, such as a coolant temperature Tw from a temperature sensor 22a that detects the coolant temperature of the engine 22, an engine speed Nin from an engine speed sensor 41a attached to the input shaft 41 of the automatic transmission 40, an engine speed Nmi from an engine speed sensor 44a attached to the transmission input shaft 44 of the automatic transmission 40, an engine speed Nout from an engine speed sensor 42a attached to the output shaft 42 of the automatic transmission 40, an accelerator opening Acc from an accelerator pedal position sensor 84 that detects the amount of depression of an accelerator pedal 83, a vehicle speed V from a vehicle speed sensor 87, and an on / off state Stw of a heater that heats the passenger compartment. The ECU 70 outputs control signals to the engine 22, the inverter 32, the clutch K0, and the hydraulic control device via output ports.The ECU 70 calculates the rotation speed ratio Gt of the automatic transmission 40 by dividing the rotation speed Nin from the rotation speed sensor 41a by the rotation speed Nout from the rotation speed sensor 42a.

[0011] The hybrid vehicle 20 of the embodiment configured as described above is controlled by the ECU 70 to travel in a hybrid driving mode (HV driving mode) in which the clutch K0 is engaged and the vehicle travels using power from the engine 22, or in an electric driving mode (EV driving mode) in which the clutch K0 is disengaged and the vehicle travels without using power from the engine 22. In controlling the automatic transmission 40 in the HV driving mode or the EV driving mode, the ECU 70 sets a target gear position M* of the automatic transmission 45 based on the accelerator opening Acc and the vehicle speed V, and controls the automatic transmission 45 so that the gear position M of the automatic transmission 45 matches the target gear position M*. In controlling the engine 22 and motor 30 in the HV driving mode, the ECU 70 sets the required torque Tout* required for driving (required from the output shaft 42 of the automatic transmission 40) based on the accelerator opening Acc and the vehicle speed V, sets the required torque Tout* of the output shaft 42 divided by the rotation speed ratio Gt of the automatic transmission 40 as the required torque Tin* of the input shaft 41, sets the target torque Te* of the engine 22 and the torque command Tm* of the motor 30 so that the required torque Tin* is output to the input shaft 41, controls the operation of the engine 22 so that the engine 22 operates at the target torque Te*, and controls the switching of the multiple switching elements of the inverter 32 so that the engine 22 is driven at the torque command Tm*. In controlling the motor 30 in the EV driving mode, the ECU 70 basically sets the required torque Tin* of the input shaft 41, as in the HV driving mode, sets the torque command Tm* of the motor 30 so that the required torque Tin* is output to the input shaft 41, and controls the switching of the multiple switching elements of the inverter 32 so that the motor 30 is driven by the torque command Tm*. Also, in the hybrid vehicle 20 of the embodiment, under the control of the ECU 70, when the temperature of the hydraulic oil in the hydraulic control device that controls the lock-up clutch LU is below a predetermined temperature or when sufficient hydraulic pressure cannot be ensured to control the lock-up clutch LU, the hybrid vehicle 20 travels in a motor torque converter driving mode in which the lock-up clutch LU is released and the torque of the motor 30 is transmitted to the transmission input shaft 44 via the torque converter 43.

[0012] Next, the operation of the hybrid vehicle 20 of the embodiment configured as described above will be described. Fig. 2 is a flowchart showing an example of a target value setting routine executed by the ECU 70. This routine is executed while the vehicle is traveling in the EV traveling mode with the accelerator opening Acc at a value of 0 and the vehicle speed V at or below a predetermined vehicle speed Vref (a value obtained by converting the minimum rotation speed at which the engine 22 can be stably operated into a vehicle speed, such as 10 km / h).

[0013] When this routine is executed, the ECU 70 inputs the vehicle speed V detected by the vehicle speed sensor 87, the coolant temperature Tw detected by the temperature sensor 22a, and the heating state Stw (on or off) (step S100), and sets the self-sustaining (idling) speed Nidl of the engine 22 based on the coolant temperature Tw and the heating state Stw (step S110). The self-sustaining speed Nidl is set to be higher when the coolant temperature Tw is low than when it is high, and higher when the heating is on than when it is off. Note that in step S110, the self-sustaining speed Nidl may be set based only on the coolant temperature Tw. Next, it is determined whether the current mode is the motor torque converter operation mode (step S120). If the current mode is not the motor torque converter operation mode, the ECU 70 calculates a torque estimate (estimated creep torque) Tc as an estimate of the creep torque output to the transmission input shaft 44 when the engine 22 is operating independently (in operation) (step S130). In estimating the torque estimated value Tc, the rotation speed Nmi from the rotation speed sensor 44a is divided by the rotation speed Nin of the input shaft 41, i.e., the self-sustaining rotation speed Nidl, to calculate the speed ratio e (=Nmi / Nidl). Then, the torque capacity coefficient C and the torque ratio t corresponding to the calculated speed ratio e are derived from a performance curve of the torque converter 43 that indicates the relationship between the torque ratio t (the value obtained by dividing the torque T2 output to the transmission input shaft 44 by the torque T1 output to the input shaft 41), the torque capacity coefficient (the value obtained by dividing the torque T1 output to the input shaft 41 by the square of the rotation speed Nmi of the input shaft 41), and the speed ratio (the value obtained by dividing the rotation speed from the rotation speed sensor 44a by the rotation speed of the input shaft 41). Then, the torque capacity coefficient C and the torque ratio t that correspond to the calculated speed ratio e are calculated using the derived torque capacity coefficient C and the self-sustaining rotation speed Nidl. 2), and calculates torque T2 (= T1·t) output to transmission input shaft 44 using torque ratio t and torque T1, and sets torque T2 to torque estimate value Tc. Next, ECU 70 sets the calculated torque estimate value Tc as torque command Tm* for motor 30 (step S140), and ends this routine. Having set torque command Tm* in this manner, ECU 70 drives motor 30 with torque command Tm*. Now, because accelerator opening Acc is 0 and vehicle speed V is equal to or less than predetermined vehicle speed Vref, when the vehicle transitions to HV driving mode, engine 22 operates autonomously (idling), and torque estimate value Tc is output to transmission input shaft 44. In this embodiment, because motor 30 outputs torque equal to torque estimate value Tc during EV driving, it is possible to suppress torque fluctuations in transmission input shaft 44 after transitioning to HV driving mode, thereby suppressing any discomfort felt by the driver. If the motor torque converter driving mode is selected in step S120, the estimated rotation speed (the self-sustaining rotation speed Nidl) is set as the target rotation speed Nm* of the motor 30 as an estimate of the rotation speed of the engine 22 when the engine 22 is assumed to be operating (step S150). The target gear M* of the automatic transmission 45 is set using the vehicle speed V and the target rotation speed Nm* so that the rotation speed of the motor 30 (the rotation speed Nin of the input shaft 41) becomes the target rotation speed Nm* (step S160), and the routine ends. After setting the target gear M* in this manner, the ECU 70 controls the hydraulic control device of the automatic transmission 45 so that the gear M of the automatic transmission 45 becomes the target gear M*. As described above, when the vehicle transitions to driving in the HV driving mode, the engine 22 operates self-sustainingly. In the embodiment, during EV driving, the rotation speed of the motor 30 is set to the self-sustaining rotation speed Nidl and the rotation speed Nmi of the transmission input shaft 44 is set to the self-sustaining rotation speed Nidl, so that changes in the rotation speed of the transmission input shaft 44 after transitioning to driving in HV driving mode can be suppressed, and discomfort felt by the driver can be suppressed.

[0014] According to the hybrid vehicle 20 of the embodiment described above, when the vehicle is traveling in EV driving mode with the vehicle speed V equal to or lower than the predetermined vehicle speed Vref, the torque estimate value Tc is calculated based on the coolant temperature Tw of the engine 22, and the motor 30 is controlled so that the motor 30 outputs torque equal to the torque estimate value Tc, thereby reducing the sense of discomfort felt by the driver. Furthermore, when the lock-up clutch LU is in a disengaged state while the hybrid vehicle 20 is traveling in EV driving mode with the vehicle speed V equal to or lower than the predetermined vehicle speed Vref, the self-sustaining rotation speed Nidl is set based on the coolant temperature Tw of the engine 22, and the automatic transmission 45 is controlled so that the rotation speed of the motor 30 is equal to the self-sustaining rotation speed Nidl, thereby reducing the sense of discomfort felt by the driver.

[0015] In the embodiment, the present invention is illustrated as being applied to hybrid vehicle 20 of Fig. 1. However, as shown in Fig. 3, the present invention may also be applied to a hybrid vehicle 120 in which rotating shaft 31 of motor 30 is connected to crankshaft 23 of engine 22 via torque converter 43 and clutch K0 and rotating shaft 31 is connected to transmission input shaft 44 via clutch WSC, or to a hybrid vehicle in which rotating shaft 31 is connected to transmission input shaft 44 without the clutch WSC in hybrid vehicle 120. In this case, in the target value setting routine, steps S100, S110, S130, and S140 may be executed without executing steps S120, S150, and S160.

[0016] The above describes the form for carrying out the present invention using examples, but the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms within the scope that does not deviate from the gist of the present invention. [Explanation of symbols]

[0017] 20 hybrid vehicles, 70 electronic control units (ECUs).

Claims

[Claim 1] A hybrid vehicle comprising an engine, a motor connected to an output shaft of the engine at least via a clutch, an automatic transmission whose output shaft is connected to wheels, a torque converter having a lock-up clutch and arranged between the clutch and an input shaft of the automatic transmission, and a control device that controls the engine, the automatic transmission, and the motor to run by switching between a hybrid running mode in which the clutch is in an engaged state and the vehicle runs using power from the engine, and an electric running mode in which the clutch is in a released state and the vehicle runs without using power from the engine, The control device, while traveling in the electric travel mode at a vehicle speed equal to or lower than a predetermined vehicle speed, estimates a self-sustaining rotation speed of the engine based on a coolant temperature of the engine and an on / off state of a heating device that heats the vehicle interior, and, when the lock-up clutch is not in a disengaged state, calculates a creep torque estimate value as an estimate of creep torque that is output to the input shaft of the automatic transmission when it is assumed that the engine is operating, using the self-sustaining rotation speed, and controls the motor so that torque equal to the creep torque estimate value is output from the motor, and, when the lock-up clutch is in a disengaged state, controls the automatic transmission so that the rotation speed of the motor is equal to the self-sustaining rotation speed. Hybrid car.

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