JP2021054135A - Control method and control device for hybrid vehicle - Google Patents

Abstract

To provide a control method for a hybrid vehicle which exhibits a power performance responding to a driving force demand with a good response while suppressing fuel consumption in an engine when a mode transition request from an EV mode to an HEV mode is made.SOLUTION: In a control method for a hybrid vehicle which performs mode transition control between an EV mode and an HEV mode, if there is a transition request to the HEV mode during selection of the EV mode in which operation of the engine 1 is stopped, engine start is begun to put the engine 1 in autonomous operation. After beginning of the engine start, when an engine rotation speed Ne reaches a fuel cut starting rotation speed Ne (F/C) which is set according to a target motor rotation speed tNm, a fuel cut to the engine 1 is started. After starting of the fuel cut, when a fuel cut timer value T (F/C) set according to the target motor rotation speed tNm elapses, the fuel cut is returned to fuel injection.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control method and a control device for a hybrid vehicle in which an engine and a motor are mounted as a driving drive source for traveling.

Conventionally, it is a drive control device for a hybrid vehicle having an ISG (Integrated Starter Generator) for starting an engine, and is equipped with an ECM (Engine Control Module) capable of executing F / C (Fuel Cut Off). When the engine is restarted by the ISG during the EV mode in which the engine can be stopped and run by the driving force of the motor generator, the F / C is prohibited on condition that the F / C prohibition condition is satisfied. Vehicle drive control devices are known (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2019-1302

In Patent Document 1, when the second F / C prohibition condition is not satisfied, the execution of the F / C is permitted to suppress the engine rotation speed. It is disclosed that this reduces the difference in rotational speed between the engine rotational speed and the rotational speed of the input shaft, and allows the clutch to be smoothly connected. However, in this disclosed technology, when the engine speed is suppressed by the F / C when the engine is started from the engine stopped state during the EV driving and the engine speed is shifted to the HEV driving, only the F / C is used when the vehicle speed is low. Even if the above is performed, the engine speed cannot be suppressed well in the motor speed range. For this reason, there is a problem that the difference rotation speed between the engine rotation speed and the motor rotation speed becomes large, it takes time to engage the clutch, and the driver's acceleration request may not be met.

The present invention has been made by paying attention to the above problems, and in a mode transition request scene from EV mode to HEV mode, it exhibits power performance that responds to a driving force request with good response while suppressing fuel consumption in the engine. With the goal.

In order to achieve the above object, the present invention includes an engine and a motor mounted as a driving drive source, a clutch provided between the engine and the motor, an EV mode by releasing the clutch, and an HEV mode by engaging the clutch. It is provided with a controller that performs mode transition control between the two. In this hybrid vehicle control method, if there is a mode transition request to the HEV mode during selection of the EV mode for stopping the operation of the engine, the engine starts to start the engine independently. After starting the engine start, when the engine speed that increases in rotation reaches the fuel cut start speed set according to the motor speed, the fuel cut to the engine is started. After starting the fuel cut, when the fuel cut timer time set according to the motor rotation speed elapses, the fuel cut returns to the fuel injection. When the engine speed after returning to fuel injection is in a rotation-synchronized state with the motor speed and the clutch engagement is completed, the mode transitions to the HEV mode.

Since the above-mentioned solution is adopted, in the mode transition request scene from the EV mode to the HEV mode, it is possible to exhibit the power performance that responds to the driving force request with good response while suppressing the fuel consumption in the engine.

FIG. 5 is an overall system diagram showing a drive system and a control system of an FF hybrid vehicle to which the control method and control device of the first embodiment are applied. It is a flowchart which shows the flow of the mode transition process from EV mode to HEV mode executed by the controller group of the FF hybrid vehicle. It is a mode transition map diagram which shows an example of the mode transition map of EV mode and HEV mode. It is a fuel cut start rotation speed map diagram which shows the map which determines the fuel cut start rotation speed with respect to the target motor rotation speed. It is a fuel cut timer time map diagram which shows the map which determines the fuel cut timer time with respect to the target motor rotation speed. It is an engine speed characteristic diagram which shows the engine speed characteristic when the fuel cut control of Example 1 is executed. It is a characteristic diagram which shows the experimental result of the relationship of the relation | rotation speed difference to the engine run-up apex with respect to the fuel cut start rotation speed. It is a characteristic diagram which shows the experimental result of the relationship of the rotation speed difference from the apex of the engine up to the return rotation speed when the engine is blown up and lowered with respect to the fuel cut timer time. It is a time chart which shows each characteristic in the start scene with a mode transition request from EV mode to HEV mode.

Hereinafter, a mode for implementing the control method and the control device for the hybrid vehicle of the present invention will be described with reference to the first embodiment shown in the drawings.

The control method and control device in the first embodiment are applied to an FF hybrid vehicle called a 1-motor / 2-clutch type equipped with a variator as a transmission mechanism. Hereinafter, the configuration of the first embodiment will be described separately for the “overall system configuration” and the “mode transition processing configuration”.

[Overall system configuration (Fig. 1)]
As shown in FIG. 1, the drive system of the FF hybrid vehicle includes an engine 1, a first clutch 2 (clutch), a motor generator 3 (motor), a second clutch 4, a variator 5, and a final deceleration mechanism 6. A drive shaft 7 and a drive wheel 8 are provided. That is, it has a 1-motor / 2-clutch hybrid drive system configuration in which the first clutch 2, the motor generator 3, and the second clutch 4 are arranged in series. Further, although the variator 5 is provided in the drive system, the hybrid drive system configuration is such that the torque converter mounted on the engine vehicle is removed.

The FF hybrid vehicle has a hybrid vehicle mode (hereinafter referred to as "HEV mode") in which the first clutch 2 and the second clutch 4 are engaged together as drive modes, and the first clutch 2 is released and the second clutch 4 is engaged. It has an electric vehicle mode (hereinafter, referred to as "EV mode"). Then, in the mode transition from the EV mode to the HEV mode, when the motor generator 3 is used as the starter motor to start the engine 1, the second clutch 4 is slip-engaged to suppress the engine start shock.

The engine 1 is a first driving drive source for an FF hybrid vehicle. When the HEV mode is selected, control is performed to share the target engine torque obtained by subtracting the target motor torque from the target driving force. Then, while the vehicle is stopped in the EV mode, it is set to an idle stop state (IS state) in which the operation of the engine 1 is stopped in order to improve the fuel efficiency performance. The engine 1 uses the motor generator 3 as a starter motor for starting the engine when the IS is removed, but the engine 1 has a starter motor (not shown), and depending on the driving scene, the engine may be started using the starter motor. good.

The first clutch 2 is a hydraulic multi-plate friction clutch interposed between the engine 1 and the motor generator 3. The first clutch 2 is an EV mode-HEV mode switching clutch that is engaged when the HEV mode is selected and released when the EV mode is selected. When the engine is started in the mode transition from the EV mode to the HEV mode, the rotation of the motor generator 3 is transmitted to the cranking shaft of the engine 1 by the engagement capacity of the first clutch 2 to perform engine cranking.

The motor generator 3 is a three-phase alternating current rotary electric machine that serves as a second traveling drive source for the FF hybrid vehicle, and exhibits a motor function and a generator function. When the HEV mode is selected, control is performed in which the target driving force is shared between the target engine torque and the target motor torque (positive torque: driving torque, negative torque: generated torque). On the other hand, when the EV mode is selected, power running control and regeneration control are performed in which all of the target driving force is shared by the motor generator 3.

The second clutch 4 is a hydraulic multi-plate friction clutch interposed between the motor generator 3 and the variator 5. The second clutch 4 has a forward / backward switching mechanism formed by a combination of a planetary gear and a friction element that switches the input rotation direction to the variator 5 between a forward rotation direction during forward travel and a reverse rotation direction during reverse travel. Therefore, the forward clutch of the forward / backward switching mechanism is referred to as the second clutch 4 during forward traveling, and the reverse brake of the forward / backward switching mechanism is referred to as the second clutch 4 during reverse traveling.

The variator 5 is a continuously variable transmission mechanism having a function of steplessly changing the gear ratio (ratio of variator input rotation to variator output rotation) by changing the belt contact diameter. The variator 5 includes a primary pulley 51, a secondary pulley 52, a belt 53 spanning a V-shaped sheave surface of the primary pulley 51, and a V-shaped sheave surface of the secondary pulley 52. Has. The gear ratio control is performed by controlling the primary pulley pressure and the secondary pulley pressure.

The final deceleration mechanism 6 has a differential gear mechanism that provides a differential function together with a reduction gear mechanism that decelerates the secondary output rotation of the secondary pulley 52. When driving by depressing the accelerator, the driving force output from the variator 5 is transmitted to the left and right drive shafts 7 and the left and right drive wheels 8. On the other hand, when traveling on the coast by releasing the accelerator foot, the rotational driving force received from the road surface by the left and right drive wheels 8 is transmitted to the drive source via the left and right drive shafts 7 and the variator 5.

As shown in FIG. 1, the control system of the FF hybrid vehicle includes a hybrid control module 10 (hybrid controller), an engine control module 12 (engine controller), a motor controller 13, a CVT control unit 14 (clutch controller), and the like. It has. The hybrid control module 10 is abbreviated as "HCM", the engine control module 12 is abbreviated as "ECM", the motor controller 13 is abbreviated as "MC", and the CVT control unit 14 is abbreviated as "CVT-CU". Further, these controller groups 10, 12, 13, and 14 are connected by a CAN communication line 15 capable of exchanging information with each other.

The hybrid control module 10 has detection information from the accelerator opening sensor 30, vehicle speed sensor 31, engine rotation sensor 32, motor rotation sensor 33, primary rotation sensor 34, secondary rotation sensor 35, oil temperature sensor 36, inhibitor switch 27, and the like. Enter. Here, the accelerator opening sensor 30 detects the accelerator opening APO. The vehicle speed sensor 31 detects the vehicle speed VSP. The engine rotation sensor 32 detects the engine speed Ne. The motor rotation sensor 33 detects the motor rotation speed Nm. The primary rotation sensor 34 detects the primary rotation speed Npri (= variator input rotation speed). The secondary rotation sensor 35 detects the secondary rotation speed Nsec. The oil temperature sensor 36 detects the temperature of the shifting hydraulic oil. The inhibitor switch 37 detects a range position selected by the driver. It should be noted that these sensors do not need to be connected to the hybrid control module 10, and may be provided separately for each of the engine control module 12, the motor controller 13, and the CVT control unit 14. When the sensors are provided separately, necessary information is exchanged via the CAN communication line 15.

The hybrid control module 10 determines the target value of each unit (engine 1, first clutch 2, motor generator 3, second clutch 4, variator 5) included in the hybrid drive system based on the target driving force, and determines the actual driving force. Etc. are integrated and controlled. In addition to the driving force control, mode transition control for mode transition between the EV mode and the HEV mode is performed. The control unit that shares the mode transition control includes a mode transition request determination unit 10a and a control command output unit 10b.

The mode transition request determination unit 10a stops the operation of the engine 1, releases the first clutch 2, and engages the second clutch 4. While selecting the EV mode, the mode to the HEV mode is set based on a predetermined mode transition schedule. Determine if there is a transition request. When the mode transition request determination unit 10a determines the mode transition request, the control command output unit 10b outputs a command to the engine control module 12 to start the engine so that the stopped engine 1 is operated independently. Then, a command to start the motor rotation speed control of the motor generator 3 is output to the motor controller 13. Further, a command to start engaging the first clutch 2 is output to the CVT control unit 14.

When the engine control module 12 receives the target engine torque from the hybrid control module 10 during the operation of the engine 1, the engine control module 12 performs engine torque control to obtain the received target engine torque. In addition, when a command to start the engine start is received from the control command output unit 10b based on the mode transition request to the HEV mode, the engine is cranked and then the engine start is started by fuel supply and ignition. Then, it has a fuel cut control unit 12a that performs fuel cut control for temporarily cutting the fuel supplied to the engine 1 (stopping the fuel supply) while the engine speed is increasing after the engine is started.

After starting the engine start, the fuel cut control unit 12a starts the engine 1 when the engine speed Ne, which increases in rotation speed, reaches the fuel cut start speed Ne (F / C) set according to the target motor speed tNm. Start the fuel cut to (stop the supply of fuel to the engine 1). Then, after starting the fuel cut, when the fuel cut timer value T (F / C) set according to the target motor rotation speed tNm elapses, the control is performed to return from the fuel cut to the fuel injection. When the engine start control is started based on the mode transition request to the HEV mode, the fuel cut of the engine 1 is prohibited when the prohibition condition that the target motor rotation speed tNm is higher than the upper limit rotation speed Nm (max) is satisfied. Will be done.

The motor controller 13 is a motor torque control unit 13a and a motor rotation speed that control the operating points (motor torque, motor rotation speed) of the motor generator 3 by a control command to the inverter 16 provided between the battery 17 and the motor generator 3. It has a control unit 13b. Here, the inverter 16 has a function of converting the battery current into a three-phase AC during motor power running and converting the three-phase AC into a battery current during motor regeneration.

When the motor torque control unit 13a receives the target motor torque from the hybrid control module 10 during EV traveling or HEV traveling, the motor torque control unit 13a performs motor torque control to obtain the received target motor torque. When the motor rotation speed control unit 13b receives a command from the control command output unit 10b to start the motor rotation speed control of the motor generator 3 based on the mode transition request to the HEV mode, the motor rotation speed control unit shifts from the motor torque control to the motor rotation speed control. To do. In the motor rotation speed control, the actual motor rotation speed is controlled to converge to the target motor rotation speed (= primary rotation speed Npri + clutch slip rotation speed), and a difference rotation corresponding to the clutch slip rotation speed is generated to cause the second clutch 4 Slip fasten. Then, when the slip engagement state of the second clutch 4 is maintained in the mode transition section from the completion of the engagement of the first clutch 2 to the mode transition to the HEV mode and the mode transition to the HEV mode, the motor torque is changed from the motor rotation speed control. Control to return to control.

The CVT control unit 14 controls a gear ratio control unit 14a that controls the variator 5 by a command output to a control valve unit 19 provided between the hydraulic source 18 and the hydraulic unit, and controls the first clutch 2 and the second clutch 4. The clutch control unit 14b is provided. Here, the control valve unit 19 includes a primary pressure solenoid 20, a secondary pressure solenoid 21, a first clutch pressure solenoid 22, and a second clutch pressure solenoid 23 as hydraulic control actuators.

When the gear ratio control unit 14a receives the target primary rotation speed tNpri from the hybrid control module 10, the gear ratio control unit 14a calculates the target gear ratio based on the vehicle speed VSP at that time. Then, a hydraulic control command having a relationship between the primary pressure Ppri and the secondary pressure Psec to obtain the calculated target gear ratio is output to the primary pressure solenoid 20 and the secondary pressure solenoid 21.

When the clutch control unit 14b receives a command from the control command output unit 10b to start engaging the first clutch 2 based on the mode transition request to the HEV mode, the clutch control unit 14b outputs an initial pressure command prompting hydraulic oil filling, and then outputs a target. The first clutch pressure is controlled to output the first clutch pressure command PCL1 (C) for obtaining the first clutch engagement pressure. By this first clutch pressure control, when the engine speed Ne after the engine 1 returns from the fuel cut to the fuel injection is in a rotation-synchronized state with the motor speed Nm, the engagement of the first clutch 2 is completed. Then, when the engagement of the first clutch 2 is completed, the control for maintaining the engagement of the first clutch 2 is performed regardless of the change in the clutch input torque. The second clutch pressure of the second clutch 4 is controlled so that the transmission torque of the second clutch 4 is the fastening torque at which the driver's required torque (= target drive torque or target coast torque) is obtained.

[Mode transition processing configuration (FIGS. 2 to 5)]
FIG. 2 shows the flow of the mode transition process from the EV mode to the HEV mode executed by the controllers groups 10, 12, 13, and 14 of the FF hybrid vehicle. Hereinafter, each step in FIG. 2 will be described. This mode transition process is an idle stop state in which the operation of the engine 1 is stopped while the vehicle is stopped, and starts when the EV mode is selected, that is, when the IS is stopped in preparation for the next start.

In step S1, it is determined whether or not there is a mode transition request from the EV mode to the HEV mode following the start. If YES (with mode transition request), the process proceeds to step S2, and if NO (without mode transition request), the determination in step S1 is repeated.

Here, as shown in an example of the mode transition map of FIG. 3, it is assumed that the driving point (APO, VSP) moves from the A point to the B point by the accelerator sudden depression operation while the vehicle is stopped at the time of starting. In this case, when the operating point (APO, VSP) crosses the mode switching line from EV to HEV, a mode transition request from the EV mode to the HEV mode is output at the timing of the crossed point C.

In step S2, following the determination that there is a mode transition request in S1, the engagement of the first clutch 2 by the output of the initial pressure command is started, and the process proceeds to step S3.

In step S3, following the start of engagement of the first clutch 2 in S2, the control of the motor generator 3 is switched from the motor torque control to the motor rotation speed control, and the motor rotation speed control for slip-engaging the second clutch 4 is started. Then, the process proceeds to step S4.

In step S4, following the start of the motor rotation speed control in S3, it is determined whether or not the engine rotation speed Ne has reached the engine start rotation speed Ne (s). If YES (reaching the engine starting speed Ne (s)), the process proceeds to step S5, and if NO (not reaching the engine starting speed Ne (s)), the determination in step S4 is repeated.

Here, the "engine starting speed Ne (s)" refers to fuel injection when the motor generator 3 is used as a starter motor and the engine 1 is cranked by engaging the first clutch 2 to increase the engine speed Ne. Set to the engine speed range where ignition is possible.

In step S5, following the determination that the engine start speed Ne (s) has been reached in S4, the engine start for autonomous operation of the engine 1 is started by starting fuel injection and ignition to the engine 1, and the process proceeds to step S6. ..

In step S6, following the self-sustaining operation of the engine by fuel injection and ignition in S5, it is determined whether or not the target motor rotation speed tNm in the motor rotation speed control at that time is equal to or less than the upper limit rotation speed Nm (max). .. If YES (tNm ≤ Nm (max)), the process proceeds to step S7, and if NO (tNm> Nm (max)), the process proceeds to step S12. In the case of motor rotation speed control, since the control response and control accuracy are high, the actual motor rotation speed Nm and the target motor rotation speed tNm are highly consistent values, and the actual motor rotation is replaced with the target motor rotation speed tNm. A few Nm may be used.

Here, the "upper limit rotation speed Nm (max)" is set in the upper limit rotation speed range (for example, about 2500 rpm) in which it is necessary to suppress and reduce the rotation blow-up of the engine 1 by cutting the fuel. Therefore, in the case of an HEV start in which the driving point (APO, VSP) moves from point A to point B in FIG. 3 due to a sudden accelerator depression operation while the vehicle is stopped, the engine starts in the low vehicle speed range. Will proceed to. On the other hand, in the case of an EV start in which the driving point (APO, VSP) moves from point A to point G in FIG. 3 due to a gentle accelerator depression operation while the vehicle is stopped, a transition request to the HEV mode is made at point H in the high vehicle speed range. Is displayed, so the process proceeds to step S12 and thereafter.

In step S7, following the determination that tNm ≤ Nm (max) in S6, the fuel cut start rotation speed Ne (F / C) and the fuel cut timer value T ( F / C) is set, and the process proceeds to step S8.

Here, as shown in FIG. 4, the "fuel cut start rotation speed Ne (F / C)" is the rotation speed range from the lower limit rotation speed Nm (min) to the upper limit rotation speed Nm (max) in the idle rotation speed range. In, the higher the target motor rotation speed tNm, the higher the rotation speed proportionally. Specifically, the fuel cut start speed Ne (F / C) is aimed at keeping the engine speed slightly higher than the target motor speed tNm (for example, tNm + (100 to 200 rpm)). To set.

As shown in FIG. 5, the "fuel cut timer value T (F / C)" is the target motor in the rotation speed range from the lower limit rotation speed Nm (min) to the upper limit rotation speed Nm (max) in the idle speed range. Set the time so that the lower the rotation speed tNm, the longer it is proportionally. Specifically, the fuel cut timer value T (F) with a duration of less than 1 second is aimed at suppressing the engine speed drop destination after the engine starts up to a level that matches or slightly falls below the target motor speed tNm. Set / C).

In step S8, following the setting of Ne (F / C) and T (F / C) in S7, the actual engine speed Ne by the engine speed sensor 32 reaches the fuel cut start speed Ne (F / C). Judge whether or not. If YES (Ne reaches Ne (F / C)), the process proceeds to step S9, and if NO (Ne does not reach Ne (F / C)), the determination in step S8 is repeated.

In step S9, following the determination that Ne in S8 has reached Ne (F / C) or T in S10 has not reached T (F / C), fuel injection to engine 1 is performed. The fuel cut to be stopped is executed, and the process proceeds to step S10. When the fuel cut is started, the timer value T indicating the duration from the start time is added (counted up).

In step S10, following the fuel cut in S9, it is determined whether or not the timer value T added from the start of the fuel cut has reached the fuel cut timer value T (F / C). If YES (T reaches T (F / C)), the process proceeds to step S11, and if NO (T does not reach T (F / C)), the process returns to step S9.

In step S11, following the determination that T in S10 has reached T (F / C), the process returns from fuel cut to fuel injection, and the process proceeds to step S12.

In step S12, following the determination that tNm> Nm (max) in S6, the return to fuel injection in S11, or the determination that Ne and Nm in S12 are not rotationally synchronized, It is determined whether or not the actual engine speed Ne and the actual motor speed Nm are rotation-synchronized (Ne = Nm). If YES (Ne and Nm are rotationally synchronized), the process proceeds to step S13, and if NO (Ne and Nm are not rotationally synchronized), the determination in step S12 is repeated.

In step S13, following the determination that Ne and Nm in S12 are rotationally synchronized, it is determined that the first clutch 2 has been engaged, and the process proceeds to step S14.

In step S14, following the completion of engagement of the first clutch 2 in S13, the mode transitions to the HEV mode, the control of the motor generator 3 shifts from the motor rotation speed control to the motor torque control, and the process proceeds to the end.

Next, "problems of background technology and problem-solving measures" will be described. Then, the "engine start-start action from idle stop" in the first embodiment will be described.

[Problems of background technology and problem-solving measures (Figs. 6 to 8)]
The background technology for starting the engine from idle stop in a hybrid vehicle is as follows. If there is a mode transition request to the HEV mode while the EV mode for stopping the engine operation is selected, the clutch engagement is started and the engine cranking is started, and the engine is started to shift to the independent operation. The engine speed rises due to the self-sustaining operation of the engine, and then when the engine speed is synchronized with the motor speed, the clutch engagement is completed, the mode transitions to the HEV mode, and the driving force of the engine and motor combined It is to start accelerating.

However, when the engine starts and starts, the motor speed is in the low speed range, so when the engine is started and shifted to independent operation, the engine speed rises to a speed range higher than the motor speed at once. .. Therefore, in order to bring the engine speed and the motor speed into a rotation-synchronized state, the load on the engine (clutch engagement load) increases due to the increase in the clutch engagement capacity, and the increase in the engine speed that has blown up is suppressed. wait. After that, the engine speed shifts from an increase to a decrease due to the rotational braking action of the clutch engagement load, and after waiting until the engine speed decreases to the motor rotation speed range, the clutch engagement is completed and the mode is set to HEV mode. It will be a transition.

For this reason, it takes time from the mode transition request to the HEV mode to the completion of clutch engagement (see the broken line characteristic F of the engine speed Ne in FIG. 9), and it is desired to quickly grasp the clutch and generate driving force when starting. , There was a problem that it was not possible to meet the driver's request.

On the other hand, as a method of suppressing an increase in the engine speed, a method of cutting fuel to cut off the fuel supply to the engine is known as described in Japanese Patent Application Laid-Open No. 2019-1302. However, when the increase in engine speed is suppressed by fuel cut, even if fuel cut control is performed with a fixed start / end timing condition when the vehicle speed is low, such as when starting the engine, the engine speed is changed to the motor speed. It cannot be suppressed well in the number range.

For example, in the case of fuel cut control in which the start / end timing condition is a fixed value, if the engine starting condition that matches the timing setting condition is deviated, the increase suppression of the engine speed becomes insufficient or the increase suppression becomes excessive. Therefore, even if fuel cut control is performed, the difference between the engine speed and the motor speed is delayed in shrinking, so it may take time to complete the clutch engagement and the driver's acceleration request may not be met. There was a problem.

In response to the above problems, the present inventor aims to give an appropriate start / end timing condition when performing fuel cut control as a variable value, and to obtain an appropriate suppression of increase in engine speed regardless of the difference in engine start status. It was verified by conducting an experiment from various angles. This verification result,
(A) Set the setting standard of the start / end timing condition when performing fuel cut control to the target motor speed (target motor speed) at which the engine speed is finally converged.
(B) The destination of the engine speed due to the fuel cut is determined by the value of the engine speed at which the fuel cut is started.
(C) The destination of the decrease in engine speed after the engine starts to blow up due to the fuel cut is determined by the duration of the fuel cut.
I focused on that point.

Based on the above points of interest, in the present disclosure, in the control method of the FF hybrid vehicle, when the EV mode for stopping the operation of the engine 1 is selected and there is a mode transition request to the HEV mode, the engine 1 is operated independently. Start the engine start. After starting the engine start, when the engine speed Ne, which increases in speed, reaches the fuel cut start speed Ne (F / C) set according to the target motor speed tNm, the fuel cut to the engine 1 is started. .. After starting the fuel cut, when the fuel cut timer value T (F / C) set according to the target motor rotation speed tNm elapses, the fuel cut returns to the fuel injection. When the engine speed Ne after returning to the fuel injection is in a rotation-synchronized state with the motor speed Nm and the engagement of the first clutch 2 is completed, the mode transitions to the HEV mode is adopted.

That is, after starting the engine start, when the engine speed Ne that increases in rotation reaches the fuel cut start speed Ne (F / C) set according to the target motor speed tNm, the fuel cut to the engine 1 is performed. It will be started. After starting the fuel cut, when the fuel cut timer value T (F / C) set according to the target motor rotation speed tNm elapses, control is performed to return from the fuel cut to the fuel injection. As for the engine speed characteristic at this time, as shown in FIG. 6, when the engine start is started at time t1, the engine speed Ne rises sharply. When the time t2 at which the engine speed Ne reaches the fuel cut start speed Ne (F / C), the fuel cut to the engine 1 is started, so that the ascending gradient of the engine speed Ne becomes gentle. Then, when the time t3 in which the fuel cut is continued by the fuel cut timer value T (F / C) is reached, the fuel injection is restored. Therefore, when the engine speed Ne rises up to the time t4 and rises to the target, the engine speed Ne starts to decrease immediately after the time t4, and the return speed (the speed range of the target motor speed tNm) starts at the time t5. )become.

Here, the relationship between the fuel cut start rotation speed Ne (F / C) and the rotation speed difference D to the top of the engine running up is as shown in the experimental result of FIG. 7, the fuel cut start rotation speed Ne (F / F /). It was found that it shows almost linear characteristics with respect to C). This means that the destination of the engine speed due to the fuel cut is determined by the value of the fuel cut start speed Ne (F / C) at which the fuel cut is started. Therefore, by setting the fuel cut start rotation speed Ne (F / C) according to the target motor rotation speed tNm, the rotation speed at which the engine rotation speed Ne is blown up is determined based on the target motor rotation speed tNm. Can be done.

As shown in the experimental results of FIG. 8, the relationship of the rotation speed difference E from the rising top to the returning rotation speed when the engine 1 blows up and drops with respect to the fuel cut timer value T (F / C) is the fuel. It was found that the amount of engine speed drop shows a characteristic that is almost linear with respect to the cut timer value T (F / C). This means that the destination of the decrease in engine speed after the engine 1 is blown up by the fuel cut is determined by the value of the fuel cut timer value T (F / C). Therefore, by setting the fuel cut timer value T (F / C) according to the target motor speed tNm, the target motor speed tNm can be set as the speed at which the engine speed drops after the engine 1 has blown up. It can be decided as a standard.

In this way, by performing fuel cut control using the fuel cut start rotation speed Ne (F / C) and the fuel cut timer value T (F / C) set according to the target motor rotation speed tNm, the engine 1 can be blown. The engine characteristics will be acquired in which the amount of decrease from the top of the engine is specified while the increase is suppressed. Therefore, when the engine start is started at time t1, the engagement of the first clutch 2 can be completed at the rotation synchronization timing at time t5. In addition, the fuel cut control suppresses the run-up of the engine 1, so that the amount of run-up fuel consumed is reduced. As a result, in the mode transition request scene from the EV mode to the HEV mode, it is possible to exhibit the power performance that responsively meets the driving force request while suppressing the fuel consumption in the engine 1.

Here, the fuel cut start rotation speed Ne (F / C) is set to a higher rotation speed as the target motor rotation speed tNm is higher (FIG. 4). That is, by setting the fuel cut start rotation speed Ne (F / C) to a higher rotation speed as the target motor rotation speed tNm is higher, as is clear from FIGS. 6 and 7, the target motor rotation speed tNm is used as a reference. It is possible to control the rotation speed difference D up to the apex by blowing up the engine speed Ne. Therefore, regardless of the height of the target motor rotation speed tNm, the fuel cut control can be performed based on the target motor rotation speed tNm and suppressing the engine rotation speed Ne to rise to the target.

Further, the fuel cut timer value T (F / C) is set to a longer time as the target motor rotation speed tNm is lower (FIG. 5). That is, by setting the fuel cut timer value T (F / C) to a longer time as the target motor rotation speed tNm is lower, as shown in FIGS. 6 and 8, when the engine 1 blows up and drops, it blows up. It is possible to control the rotation speed difference E from the rising peak to the returning rotation speed. Therefore, regardless of the height of the target motor rotation speed tNm, the fuel cut control can be performed so that the drop destination of the engine rotation speed Ne is adjusted to the region of the target motor rotation speed tNm.

[Engine start-start action from idle stop (Figs. 2 and 9)]
First, the mode transition processing action from the EV mode to the HEV mode will be described based on the flowchart shown in FIG. If there is a mode transition request from the EV mode to the HEV mode in the idle stop state in which the operation of the engine 1 is stopped while the vehicle is stopped, the process proceeds to S1 → S2 → S3 → S4. In S2, the engagement control of the first clutch 2 is started by the output of the initial pressure command. In S3, the control of the motor generator 3 is switched from the motor torque control to the motor rotation speed control, and the motor rotation speed control for slip-fastening the second clutch 4 is started. In S4, after the motor generator 3 is used as a starter motor and the engine cranking is started by engaging the first clutch 2, it is determined whether or not the engine speed Ne has reached the engine starting speed Ne (s).

When it is determined in S4 that the engine speed Ne has reached the engine starting speed Ne (s), the process proceeds from S4 to S5 → S6. In S5, the engine start for autonomous operation of the engine 1 is started by the start of fuel injection and the start of ignition to the engine 1. In S6, it is determined whether or not the target motor rotation speed tNm in the motor rotation speed control at that time is equal to or less than the upper limit rotation speed Nm (max).

If it is determined in S6 that the target motor rotation speed tNm is equal to or less than the upper limit rotation speed Nm (max), the process proceeds from S6 to S7 → S8. In S7, the fuel cut start rotation speed Ne (F / C) and the fuel cut timer value T (F / C) are set according to the target motor rotation speed tNm at that time. In S8, it is determined by the engine rotation sensor 32 whether or not the actual engine rotation speed Ne has reached the fuel cut start rotation speed Ne (F / C). When it is determined in S8 that the actual engine speed Ne has reached the fuel cut start speed Ne (F / C), the process proceeds from S8 to S9 → S10. In S9, a fuel cut is executed to stop the fuel injection to the engine 1. In S10, it is determined whether or not the timer value T added from the start of the fuel cut has reached the fuel cut timer value T (F / C).

When it is determined in S10 that the timer value T has reached the fuel cut timer value T (F / C), the process proceeds from S10 to S11 → S12. In S11, the fuel cut is restored to the fuel injection. In S12, it is determined whether or not the actual engine speed Ne and the actual motor speed Nm are rotation-synchronized (Ne = Nm). When it is determined in S12 that the actual engine rotation speed Ne and the actual motor rotation speed Nm are rotationally synchronized, the process proceeds from S12 to S13 → S14 → end. In S13, it is determined that the first clutch 2 has been engaged. In S14, the mode transition to the HEV mode is performed, and the control of the motor generator 3 is shifted from the motor rotation speed control to the motor torque control.

On the other hand, if it is determined in S6 that the target motor rotation speed tNm exceeds the upper limit rotation speed Nm (max), the process proceeds from S6 to S12. Then, when it is determined in S12 that the actual engine rotation speed Ne and the actual motor rotation speed Nm are rotationally synchronized, the process proceeds from S12 to S13 → S14 → end. Proceed to S13 → S14 → end. That is, when the target motor rotation speed tNm exceeds the upper limit rotation speed Nm (max), the fuel cut control of S7 to S11 is prohibited, the first clutch 2 is engaged (S13), the mode transition to the HEV mode, and the mode transition to the HEV mode. The transition to motor torque control (S14) is performed.

Next, the engine starting / starting action from the idle stop will be described based on the time chart of FIG. 9 showing each characteristic in the starting scene where there is a mode transition request from the EV mode to the HEV mode.

If the driver performs a start operation by stepping on the accelerator at time t1 while the EV mode is stopped in the idle stop state, the IS flag is switched from ON to OFF and the IS is omitted, and a mode transition request to the HEV mode is issued. .. At the same time, at time t1, the engagement control of the first clutch 2 is started by the output of the first clutch pressure command PCL1 (C) by the initial pressure, and the motor rotation speed that converges the actual motor rotation speed Nm to the target motor rotation speed tNm. Control is started.

Then, when the engagement capacity of the first clutch 2 becomes high and the time t2 at which the cranking of the engine 1 is started with the motor generator 3 as the starter motor is reached, the engine speed Ne rises sharply. When the engine speed Ne becomes the engine start speed Ne (s) at the time t3 immediately after that, the engine start for autonomous operation of the engine 1 is started by the start of fuel injection and the start of ignition to the engine 1.

When the engine speed Ne reaches the fuel cut start speed Ne (F / C) at time t4 after the start of the engine start, the fuel cut to the engine 1 is started. When the fuel cut is started, the ascending gradient of the engine speed Ne becomes gentle, and the engine speed Ne is suppressed to rise to the target.

Then, when the duration from the time t4 reaches the time t5 when the fuel cut timer value T (F / C) is reached, the fuel cut returns to the fuel injection. When the fuel cut is continued for the fuel cut timer value T (F / C) and then returned to the fuel injection, the engine speed Ne starts to rise and starts to decrease from the peak, then converges to the return speed range and then rises again. Turn to.

Therefore, when the time t6 is reached and the engine speed Ne matches the motor speed Nm, the first clutch 2 is in a completely engaged state with no differential rotation. From this time t6, the mode transitions to the HEV mode, and the control of the motor generator 3 is switched from the motor rotation speed control to the motor torque control.

In this way, when the engine starts from the idle stop, it is defined by the fuel cut start speed Ne (F / C) and the fuel cut timer value T (F / C) in the rising range of the engine speed Ne after the engine starts. The fuel cut to be done is temporarily intervened. Therefore, as compared with the case where the fuel cut is not intervened in the rising region of the engine speed Ne after the engine is started (engine speed characteristic F in FIG. 9), the rotation synchronization is achieved with good response and the first clutch 2 is gripped at an early stage. be able to. Therefore, when the engine is started from the idle stop, the mode transitions to the HEV mode with good response to the acceleration request operation, so that the power performance that meets the driving force request of the driver can be exhibited.

As described above, in the control method and control device of the FF hybrid vehicle of the first embodiment, the effects listed below can be obtained.

(1) The engine 1 and the motor (motor generator 3) mounted as a driving drive source, the clutch (first clutch 2) provided between the engine 1 and the motor, and the EV mode and the clutch by releasing the clutch. In the control method of a hybrid vehicle including a controller (controller group 10, 12, 13, 14) that performs mode transition control with the HEV mode by engagement.
If there is a mode transition request to the HEV mode while the EV mode for stopping the operation of the engine 1 is selected, the engine start for the engine 1 to operate independently is started.
After starting the engine, when the engine speed Ne, which increases in speed, reaches the fuel cut start speed Ne (F / C) set according to the motor speed Nm (target motor speed tNm), the engine goes to engine 1. Start fuel cut,
After starting the fuel cut, when the fuel cut timer value T (F / C) set according to the motor rotation speed Nm (target motor rotation speed tNm) elapses, the fuel cut returns to the fuel injection.
When the engine speed Ne after returning to the fuel injection is in a rotation-synchronized state with the motor speed Nm and the clutch engagement is completed, the mode transitions to the HEV mode.
Therefore, in the mode transition request scene from the EV mode to the HEV mode, it is possible to provide a control method for a hybrid vehicle that exhibits power performance that responds to the driving force demand with good response while suppressing fuel consumption in the engine 1.

(2) The fuel cut start rotation speed Ne (F / C) is set to a higher rotation speed as the motor rotation speed Nm (target motor rotation speed tNm) increases.
Therefore, regardless of the height of the motor speed Nm (target motor speed tNm), the fuel cut control can be used to suppress the engine speed Ne to rise to the target by using the motor speed Nm as a reference. it can.

(3) The fuel cut timer value T (F / C) is set to a longer time as the motor rotation speed Nm (target motor rotation speed tNm) is lower.
Therefore, regardless of the height of the motor rotation speed Nm (target motor rotation speed tNm), the fuel cut control can be performed so that the drop destination of the engine rotation speed Ne is adjusted to the region of the motor rotation speed Nm.

(4) When the engine start control is started based on the mode transition request to the HEV mode, when the prohibition condition that the motor rotation speed Nm (target motor rotation speed tNm) is higher than the upper limit rotation speed Nm (max) is satisfied, Prohibit fuel cut of engine 1.
Therefore, when the motor rotation speed Nm (target motor rotation speed tNm) becomes higher than the upper limit rotation speed Nm (max) due to the increase in vehicle speed after the EV starts and there is a mode transition request to the HEV mode, the clutch (first clutch 2) ), It is possible to prevent the vehicle speed VSP from decreasing due to the decrease in engine speed due to the execution of fuel cut. That is, by prohibiting the fuel cut when the clutch (first clutch 2) is engaged, the engine speed Ne can be brought close to the motor speed Nm without hindering the increase in the engine speed Ne.

(5) A first clutch 2 as a clutch, a motor (motor generator 3), and a second clutch 4 are provided in series between the engine 1 and the drive wheels 8 of the hybrid drive system.
If there is a mode transition request to the HEV mode while selecting the EV mode, the motor rotation speed Nm is added to the output rotation speed (= primary rotation speed Npri) of the second clutch 4 and the clutch slip rotation speed is added to the target motor rotation speed. Start motor speed control with tNm,
The second clutch slip control by the motor rotation speed control is performed until the mode transitions to the HEV mode when the engagement of the first clutch 2 is completed.
Therefore, by continuing the slip control of the second clutch 4 in the transitional period of the mode transition from the EV mode to the HEV mode, good operability can be exhibited while suppressing the engine start shock and the clutch engagement shock. .. That is, by continuing the slip engagement control of the second clutch 4 in the mode transition transition period, the engine start shock and the clutch engagement shock are absorbed by the clutch slip.

(6) The engine 1 and the motor (motor generator 3) mounted as a driving drive source, the first clutch 2 provided between the engine 1 and the motor, and the second clutch provided between the motor and the drive wheel 8. 2 In a hybrid vehicle control device including a clutch 4, a hybrid controller (hybrid control module 10), an engine controller (engine control module 12), a motor controller 13, and a clutch controller (CVT control unit 14).
The hybrid controller (hybrid control module 10) is
While selecting the EV mode in which the operation of the engine 1 is stopped, the first clutch 2 is released, and the second clutch 4 is engaged, the mode transition request determination unit 10a for determining whether or not there is a mode transition request to the HEV mode, and
When the mode transition request determination unit 10a determines the mode transition request, the mode transition request determination unit 10a outputs a command to start the engine start for autonomous operation of the engine 1 to the engine controller, and issues a command to start the motor rotation speed control of the motor to the motor controller 13. It has a control command output unit 10b that outputs to the clutch controller and outputs a command to start engagement of the first clutch 2 to the clutch controller.
In the engine controller (engine control module 12), after starting the engine start, the engine rotation speed Ne that increases in rotation is set according to the motor rotation speed Nm (target motor rotation speed tNm). When the F / C is reached, the fuel cut to the engine 1 is started, and after the fuel cut is started, the fuel cut timer value T (F / C) set according to the motor rotation speed Nm (target motor rotation speed tNm) is started. ), It has a fuel cut control unit 12a that controls the return from fuel cut to fuel injection.
After starting the motor rotation speed control, the motor controller 13 controls the actual motor rotation speed Nm to the target motor rotation speed tNm, slips and engages the second clutch 4, and shifts to the motor torque control when the mode transitions to the HEV mode. It has a motor rotation speed control unit 13b for controlling, and has a motor rotation speed control unit 13b.
When the engine rotation speed Ne after returning to fuel injection is synchronized with the motor rotation speed Nm and the engagement of the first clutch 2 is completed, the clutch controller (CVT control unit 14) is affected by the change in the clutch input torque. It has a clutch control unit 14b that controls to maintain the engagement of the first clutch 2.
For this reason, in the mode transition request scene from EV mode to HEV mode, a hybrid vehicle that exhibits power performance that responds to driving force demands with good response and good drivability with suppressed shock while suppressing fuel consumption in engine 1. Control device can be provided.

The control method and control device for the hybrid vehicle of the present invention have been described above based on the first embodiment. However, the specific configuration is not limited to the first embodiment, and design changes and additions are permitted as long as the gist of the invention according to each claim is not deviated from the claims.

In Example 1, an example in which the motor generator 3 is used as a starter motor is shown. However, an example may be provided in which a starter motor is provided separately from the motor generator as a driving drive source for traveling.

In the first embodiment, an example is shown in which the control method and the control device of the present invention are provided with a variator 5 as a transmission mechanism in a hybrid drive system. However, the control method and control device of the present invention may or may not have a transmission mechanism, and the transmission mechanism is also a stepped transmission mechanism having a plurality of transmission stages other than a variator or a continuously variable transmission mechanism with an auxiliary transmission. Is also good.

In Example 1, an example of applying the control method and control device of the present invention to an FF hybrid vehicle called a 1-motor / 2-clutch type is shown. However, the type of hybrid vehicle to which the control method and control device of the present invention is applied is not limited to the 1-motor / 2-clutch type FF hybrid vehicle, and may be an FR hybrid vehicle. Further, it can be applied to hybrid vehicles of other types such as a motor assist type hybrid vehicle in which a motor is added to the drive system of an engine vehicle, a power split type hybrid vehicle using a planetary gear mechanism, and the like. In short, any hybrid electric vehicle that has an EV mode and an HEV mode and that starts the engine and engages the clutch at the time of mode transition from the EV mode to the HEV mode may be used.

1 Engine 2 1st clutch (clutch)
3 Motor generator (motor)
4 2nd clutch 5 Variator 6 Final deceleration mechanism 7 Drive shaft 8 Drive wheels 10 Hybrid control module (hybrid controller)
10a Mode transition request judgment unit 10b Control command output unit 12 Engine control module (engine controller)
12a Fuel cut control unit 13 Motor controller 13b Motor speed control unit 14 CVT control unit (clutch controller)
14b Clutch control unit 30 Accelerator opening sensor 31 Vehicle speed sensor 32 Engine rotation sensor 33 Motor rotation sensor 34 Primary rotation sensor

Claims (6)

Mode transition control is performed between an engine and a motor mounted as a driving drive source, a clutch provided between the engine and the motor, and an EV mode by releasing the clutch and an HEV mode by engaging the clutch. In the control method of a hybrid vehicle equipped with a controller to perform
When there is a mode transition request to the HEV mode during the selection of the EV mode for stopping the operation of the engine, the engine start for the engine to operate independently is started.
After starting the engine start, when the engine speed that increases in rotation reaches the fuel cut start speed set according to the motor speed, the fuel cut to the engine is started.
After starting the fuel cut, when the fuel cut timer time set according to the motor rotation speed elapses, the fuel cut returns to the fuel injection, and the fuel injection is resumed.
A control method for a hybrid vehicle, characterized in that the mode transitions to the HEV mode when the engine speed after returning to the fuel injection is in a rotation-synchronized state with the motor speed and the engagement of the clutch is completed. In the hybrid vehicle control method according to claim 1,
A control method for a hybrid vehicle, wherein the fuel cut start rotation speed is set to a higher rotation speed as the motor rotation speed is higher. In the method for controlling a hybrid vehicle according to claim 1 or 2.
A control method for a hybrid vehicle, wherein the fuel cut timer time is set to a longer time as the motor rotation speed is lower. In the method for controlling a hybrid vehicle according to any one of claims 1 to 3,
When the engine start control is started based on the mode transition request to the HEV mode, the fuel cut of the engine is prohibited when the prohibition condition that the motor rotation speed is higher than the upper limit rotation speed is satisfied. How to control a hybrid vehicle. In the method for controlling a hybrid vehicle according to any one of claims 1 to 4.
A first clutch as the clutch, the motor, and the second clutch are provided in series between the engine and the drive wheels of the hybrid drive system.
When there is a mode transition request to the HEV mode during the selection of the EV mode, the motor rotation speed is set to the target motor rotation speed obtained by adding the clutch slip rotation speed to the output rotation speed of the second clutch. Start control and
A control method for a hybrid vehicle, wherein the second clutch slip control by the motor rotation speed control is performed until the mode transitions to the HEV mode when the engagement of the first clutch is completed. An engine and a motor mounted as a driving drive source, a first clutch provided between the engine and the motor, a second clutch provided between the motor and the drive wheels, a hybrid controller, and an engine. In a hybrid vehicle control device including a controller, a motor controller, and a clutch controller,
The hybrid controller
A mode transition request determination unit that determines whether or not there is a mode transition request to the HEV mode while selecting the EV mode in which the engine operation is stopped, the first clutch is released, and the second clutch is engaged.
When the mode transition request is determined by the mode transition request determination unit, a command for starting the engine start for the engine to operate independently is output to the engine controller, and a command for starting the motor rotation speed control of the motor is given. It has a control command output unit that outputs to the motor controller and outputs a command to start engaging the first clutch to the clutch controller.
After starting the engine start, the engine controller starts fuel cut to the engine when the engine speed that increases in rotation reaches the fuel cut start speed set according to the motor speed, and the fuel It has a fuel cut control unit that controls the return from fuel cut to fuel injection when the fuel cut timer time set according to the motor rotation speed elapses after starting the cut.
After starting the motor rotation speed control, the motor controller controls the actual motor rotation speed to the target motor rotation speed, slip-engages the second clutch, and shifts to the motor torque control when the mode transitions to the HEV mode. It has a motor rotation speed control unit that controls
When the engine rotation speed after returning to the fuel injection is synchronized with the motor rotation speed and the engagement of the first clutch is completed, the clutch controller of the first clutch regardless of the change in the clutch input torque. A control device for a hybrid vehicle, which comprises a clutch control unit that controls to maintain engagement.

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