WO2020065799A1

WO2020065799A1 - Electric vehicle control method and electric vehicle drive system

Info

Publication number: WO2020065799A1
Application number: PCT/JP2018/035811
Authority: WO
Inventors: 古閑　雅人; 隆行加賀谷; 中島　祐樹; 田中　克典
Original assignee: 日産自動車株式会社
Priority date: 2018-09-26
Filing date: 2018-09-26
Publication date: 2020-04-02

Abstract

This electric vehicle drive system includes an internal combustion engine, an electricity generation motor disposed so as to be capable of generating electricity by receiving motive power from the internal combustion engine, and a travel motor disposed so as to be capable of being driven by the electricity generated by the electricity generation motor. The electric vehicle drive system is configured such that the internal combustion engine and a driving wheel are disconnectably connected by means of a first clutch and the travel motor and the driving wheel are disconnectably connected by means of a second clutch different from the first clutch, thereby allowing switching between a series hybrid mode in which the vehicle is caused to travel by transmitting the motive power from the travel motor serving as a driving source to the driving wheel, and an engine direct-connection mode in which the vehicle is caused to travel by making at least one from among the internal combustion engine and a generator serve as a driving source and transmitting the motive power from the driving source to the driving wheel. The electric vehicle drive system engages both the first and second clutches when switching between the series hybrid mode and engine direct-connection mode, and changes, while both the first and second clutches are engaged, the proportion of internal combustion engine torque and the proportion of travel motor torque in the total vehicle driving torque to the proportion after the mode switching. When the proportion approximates to or reaches the proportion after the mode switching, the electric vehicle drive system disengages a disengagement-side clutch from among the first and second clutches.

Description

ELECTRIC VEHICLE CONTROL METHOD AND ELECTRIC VEHICLE DRIVE SYSTEM

The present invention relates to a control method and a drive system for an electric vehicle configured to be able to run by switching between a series hybrid mode and an engine direct connection mode.

There is known a series hybrid drive system configured to drive a generator by the power of an internal combustion engine and to operate an electric motor for traveling (hereinafter referred to as “traveling motor”) by electric power generated by the generator. ing. JP 2004-123060A, as such a drive system, is provided with a clutch capable of connecting and disconnecting the internal combustion engine and the drive wheels, and configured to be able to transmit the power of the internal combustion engine to the drive wheels without using a traveling motor. One is disclosed (FIG. 7).

According to the drive system disclosed in JP2004-123060A, when traveling in the engine direct connection mode in which the internal combustion engine is directly connected to the drive wheels, simply by connecting the internal combustion engine and the drive wheels via the clutch, the drive motor and the drive are driven. The connection with the wheels is not interrupted, and the traveling motor is rotated by the drive wheels. As a result, there is a problem in that the friction of the traveling motor becomes a load in propulsion of the vehicle, thereby deteriorating the efficiency of the entire system and reducing the power consumption, which is the travelable distance per unit amount of power.

An object of the present invention is to provide a control method for an electric vehicle and a drive system for an electric vehicle in consideration of the above problems.

In one aspect, an internal combustion engine includes: an internal combustion engine; a power generation motor disposed so as to be able to generate power by receiving the power of the internal combustion engine; and a traveling motor disposed so as to be driven by the electric power generated by the power generation motor. And the driving wheels are connected via a first clutch so as to be able to be connected and disconnected, while the traveling motor and the driving wheels are connected so as to be able to be connected and disconnected via a second clutch different from the first clutch. A series hybrid mode in which the power of a traveling motor is transmitted to driving wheels as a driving source to travel, and a traveling mode in which at least one of an internal combustion engine and a generator is used as a driving source and the power of the driving source is transmitted to driving wheels. And a control method for an electric vehicle configured to be able to switch between an engine direct connection mode and an engine direct connection mode. In this aspect, at the time of mode switching for switching between the series hybrid mode and the engine direct connection mode, both the first clutch and the second clutch are engaged, and while both the first and second clutches are engaged, the internal combustion engine is switched on. The ratio of each of the torque and the torque of the traveling motor to the total drive torque of the vehicle is changed toward the ratio after the mode switching, and when the ratio approaches or reaches the ratio after the mode switching, the first and the second are performed. The clutch on the release side of the two clutches is released.

In another aspect, a drive system for an electric vehicle is provided.

FIG. 1 is a schematic diagram showing an overall configuration of a drive system for an electric vehicle according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing an operation in a series hybrid mode of the drive system according to the embodiment. FIG. 3 is an explanatory diagram showing an operation of the drive system according to the embodiment in an engine direct connection mode. FIG. 4 is an explanatory diagram showing a driving mode according to the driving area of the drive system according to the embodiment. FIG. 5 is a flowchart showing an overall flow of the mode switching control according to the embodiment. FIG. 6 is a flowchart showing the contents of a process in a torque change phase of the mode switching control according to the embodiment. FIG. 7 is an explanatory diagram showing an example of an operation by mode switching control according to one embodiment of the present invention when switching from the series hybrid mode to the engine direct connection mode. FIG. 8 is an explanatory diagram showing an operation according to a comparative example when switching from the series hybrid mode to the engine direct connection mode. FIG. 9 is an explanatory diagram showing an example of an operation by mode switching control according to one embodiment of the present invention when switching from the engine direct connection mode to the series hybrid mode. FIG. 10 is a flowchart showing the content of the processing in the torque change phase of the mode switching control according to another embodiment of the present invention. FIG. 11 is an explanatory diagram showing an example of an operation by mode switching control according to another embodiment of the present invention when switching from the series hybrid mode to the engine direct connection mode. FIG. 12 is an explanatory diagram illustrating an operation according to another comparative example when switching from the series hybrid mode to the engine direct connection mode. FIG. 13 is an explanatory diagram showing an example of an operation by mode switching control according to another embodiment of the present invention when switching from the engine direct connection mode to the series hybrid mode. FIG. 14 is an explanatory diagram showing an example of an operation by mode switching control according to still another embodiment of the present invention when switching from the series hybrid mode to the engine direct connection mode.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an overall configuration of a drive system S for an electric vehicle according to an embodiment of the present invention.

The drive system (hereinafter, simply referred to as “drive system”) S according to the present embodiment is mounted on an electric vehicle and constitutes a propulsion device of the vehicle. The drive system S includes an internal combustion engine 1, an electric motor for power generation (hereinafter, referred to as “generation motor”) 2, and an electric motor for traveling (hereinafter, referred to as “travel motor”) 3.

An internal combustion engine (hereinafter simply referred to as “engine”) 1 has an output shaft or crankshaft 11 connected to a rotating shaft 21 of a generator motor 2 via a gear train Ga composed of a plurality of gears. The torque of the engine 1 is transmitted to the generator motor 2 through the gear train Ga at a predetermined gear ratio, and the generator motor 2 is operated. In the present embodiment, the connection between the engine 1 and the generator motor 2 via the gear train Ga is permanent, that is, cannot be cut off.

The generator motor 2 is electrically connected to the traveling motor 3 and connected to the battery 4, and supplies power generated by receiving power from the engine 1 to the traveling motor 3 or the battery 4. . The supply of electric power from the generator motor 2 to the traveling motor 3 and the supply of electric power from the generator motor 2 to the battery 4 can be executed in accordance with the operating state of the vehicle, the state of charge of the battery 4, and the like. FIG. 1 schematically shows the electrical connection between the generator motor 2, the traveling motor 3, and the battery 4 by a two-dot chain line.

The traveling motor 3 is electrically connected to the battery 4, and the rotating shaft 31 is connected to a ring gear of the differential 5 via a gear train Gb including a plurality of gears. The torque of the traveling motor 3 is transmitted to the differential 5 at a predetermined gear ratio through the gear train Gb, and is further distributed to the left and right drive shafts 6 via the differential 5 to rotate the drive wheels 7 to rotate the vehicle. Promote. In the present embodiment, the traveling motor 3 is configured by a motor generator that can operate not only as a generator but also as a motor, and in addition to propulsion of the vehicle, power is supplied from the driving wheels 7 via a gear train Gb. It is also possible to receive and generate electricity. The electric power generated by the traveling motor 3 can be supplied to the battery 4 and used for charging the battery 4.

Further, in the present embodiment, the output shaft 11 of the engine 1 is connected to the ring gear of the differential 5 via a gear train Gc including a plurality of gears. The torque of the engine 1 is transmitted to the differential 5 at a predetermined gear ratio through the gear train Gc, and is distributed to the left and right drive shafts 6 via the differential 5, so that the drive wheels 7 are rotated and the vehicle is propelled. Is done.

In the present embodiment, clutches c1 and c2 are interposed in each of the gear train Gc and the gear train Gb, and the connection between the engine 1 and the drive wheels 7 via the gear train Gc and the connection between the traveling motor 3 and the drive wheels 7 are established. The connection via the gear train Gb can be disconnected by the clutches c1 and c2, respectively. Each of the clutches c1 and c2 may be an engagement type clutch, and a dog clutch can be exemplified as one applicable to the clutches c1 and c2. In the present embodiment, a dock clutch is adopted as each of the clutches c1 and c2. The clutch c1 provided in the gear train Gc on the engine 1 side constitutes the "first clutch" according to the present embodiment, and the clutch c2 provided in the gear train Gb on the traveling motor 3 side corresponds to the "first clutch" according to the present embodiment. 2 clutches.

The operation of the engine 1, the generator motor 2, the traveling motor 3 and the states of the clutches c1, c2 are electronically controlled by the controller 101. Although not limited to this, the controller 101 is constituted by a microcomputer including a central processing unit (CPU), various storage units such as ROM and RAM, and an input / output interface as an electronic control unit.

(4) Information of various parameters indicating the driving state of the vehicle is input to the controller 101. In the present embodiment, a signal indicating the amount of operation of the accelerator pedal (hereinafter, referred to as “accelerator opening”) APO by the driver, a signal indicating the traveling speed of the vehicle (hereinafter, referred to as “vehicle speed”) VSP, and the rotation speed Neng of the engine 1 are shown. A signal indicating the rotation speed Nmg1 of the generator motor 2 and a signal indicating the rotation speed Nmg2 of the traveling motor 3 are input to the controller 101. In order to detect various parameters, the accelerator opening sensor 201 for detecting the accelerator opening APO, the vehicle speed sensor 202 for detecting the vehicle speed VSP, and the rotation speed Neng of the engine 1 are referred to as the number of rotations per unit time (hereinafter referred to as “engine rotation speed”). )), A generator motor speed sensor 204 that detects the rotational speed Nmg1 of the generator motor 2 as the generator motor speed, and a travel that detects the rotational speed Nmg2 of the travel motor 3 as the travel motor speed. A motor speed sensor 205 is provided.

The controller 101 performs a predetermined calculation based on the input various signals to control the operations of the engine 1, the generator motor 2 and the traveling motor 3, and also controls the states of the clutches c1 and c2.

In the present embodiment, it is possible to switch the running mode between the series hybrid mode and the engine direct mode in actual running. In the series hybrid mode, the traveling motor 3 is used as a drive source of the vehicle. In the engine direct connection mode, basically, the engine 1 is used as a drive source of the vehicle.

FIGS. 2 and 3 show the operation according to the traveling mode of the drive system S. FIG. 2 shows the operation in the series hybrid mode, and FIG. 3 shows the operation in the engine direct connection mode. 2 and 3 show the path through which the power is transmitted by a thick dotted line with an arrow, and the arrow indicates the direction in which the power is transmitted.

In the series hybrid mode, as shown in FIG. 2, the clutch c1 is released, the clutch c2 is engaged, and the torque of the engine 1 can be transmitted to the generator motor 2 through the gear train Ga. Can be transmitted to the differential 5 and the drive wheels 7 through the gear train Gb.

On the other hand, in the engine direct connection mode, as shown in FIG. 3, the clutch c1 is engaged and the clutch c2 is released, so that the torque of the engine 1 can be transmitted to the differential 5 and the drive wheels 7 through the gear train Gc. Here, since the clutch c2 on the power transmission path connecting the traveling motor 3 and the driving wheel 7 is in a disconnected state, the transmission of power between the traveling motor 3 and the driving wheel 7 is blocked, and the driving wheel The traveling motor 3 is prevented from being rotated together with the rotation of the motor 7. In the engine direct connection mode, when the power generation motor 2 is configured by a motor generator, the torque of the power generation motor 2 as well as the engine 1 can be transmitted to the drive wheels 7 through the gear trains Ga and Gc.

Switching between the series hybrid mode and the engine direct connection mode is performed by switching the engagement and disengagement states of the clutches c1 and c2 based on a signal from the controller 101.

FIG. 4 shows a traveling mode according to the driving area of the vehicle.

Roughly, the direct engine mode is selected in the high-speed range, and the series hybrid mode is selected in other areas. In the present embodiment, in the high-speed region, the engine direct connection mode is selected in a region B where the load is relatively low, and the series hybrid mode is selected in the other region A. The controller 101 determines the driving regions A and B to which the driving state of the vehicle belongs based on the vehicle speed VSP and the accelerator opening APO, and switches the driving mode according to the determination result.

制御 The control relating to the switching of the traveling mode (hereinafter referred to as “mode switching control”) will be described below. After describing the overall flow with reference to a flowchart, a more specific description will be made with reference to a time chart.

FIG. 5 shows the overall flow of the mode switching control, and FIG. 6 shows the contents of the processing in the torque switching phase in the mode switching control. In the present embodiment, the controller 101 is programmed to execute the mode switching control at a predetermined cycle.

In the flowchart shown in FIG. 5, in S101, the driving state of the vehicle is read. Specifically, an accelerator opening APO, a vehicle speed VSP, an engine speed Neng, a power generation motor speed Nmg1 and a traveling motor speed Nmg2 are read as the operation states related to the mode switching control.

In S102, it is determined whether or not the mode is switched. Specifically, the operating state of the vehicle determined by accelerator opening APO and vehicle speed VSP has shifted from area A in the series hybrid mode to area B in the direct engine mode in the operating area shown in FIG. 4, or vice versa. It is determined whether or not the state has shifted from the area B to the area A. If a transition of the operating state occurs between the operating regions A and B and the mode is being switched, the process proceeds to S103. If the mode is not switched, the control by this routine is ended.

In S103, control for matching the rotational speeds of the drive element and the driven element of the clutch on the engagement side (hereinafter referred to as “rotational synchronization control”) is started. Here, the clutch on the engagement side refers to a clutch that is engaged after mode switching (in other words, is in a released state before mode switching). For example, in the case of switching from the series hybrid mode to the engine direct connection mode Corresponds to the clutch c1 provided in the gear train Gc. Then, as the rotation synchronization control in this case, a torque is generated by the generator motor 2 to increase the generator motor rotation speed Nmg1. The rotation synchronization control can also be executed by generating torque with the engine 1 instead of the power generation motor 2 or together with the power generation motor 2.

In S104, it is determined whether the rotation synchronization has been completed. This determination is made, for example, based on whether or not the difference in rotation speed between the driving element and the driven element of the clutch on the engagement side has decreased to a predetermined value, and the rotation synchronization has been completed when the difference has decreased to the predetermined value. Is determined. When the rotation synchronization is completed, the process proceeds to S105, and when not completed, the determination of S104 is repeated until the rotation synchronization is completed. The determination as to whether or not the rotation synchronization has been completed is not limited to this, and may be made based on whether or not the state in which the difference between the rotation speeds is equal to or less than a predetermined value has continued for a predetermined time.

In S105, a command to engage the clutch is output to the clutch on the engagement side. When the clutches c1 and c2 convert the operation of an actuator (for example, a servo-type electric motor) into movement of a driving element or a driven element via a link mechanism including a cam and a lever, the clutch c1, c2 On the other hand, a command to operate in the direction to engage the clutch is output.

In S106, it is determined whether the engagement of the clutch has been completed. This determination can be made, for example, based on whether or not the actuators of the clutches c1 and c2 (specifically, the movable parts thereof) have reached a target position at the time of engagement. When the engagement of the clutch is completed, the process proceeds to S201 of the flowchart shown in FIG. 6 to execute the process in the torque transfer phase, and when not completed, the determination of S106 is repeated until the completion.

In S107, it is determined that the switching of the traveling mode has been completed, and thereafter, the processing of this routine is ended.

移 Moving to the flowchart of FIG. 6, in S201, a command to release the clutch on the release side is output. For example, a command to operate the clutches c1 and c2 in a direction to release the clutch is output. Here, the release-side clutch means a clutch that is released after the mode switching (in other words, is in a state of being engaged before the mode switching). For example, in the case of switching from the series hybrid mode to the engine direct connection mode Corresponds to the clutch c2 provided in the gear train Gb.

In S202, control for changing the torque between the driving source before the mode switching and the driving source after the mode switching is started between these driving sources. For convenience of explanation, this will be described at the time of switching from the series hybrid mode to the engine direct connection mode. To change the torque, the torque of the traveling motor 3 which is the driving source before the mode switching is reduced, and the mode is changed accordingly. This is embodied as control for increasing the torque of the engine 1, which is the drive source after switching.

In S203, it is determined whether the release of the clutch has been completed. This determination can be made, for example, based on whether or not the actuators (specifically, the movable parts thereof) of the clutches c1 and c2 have reached a target position at the time of disengagement. When the release of the clutch is completed, the process returns to the flowchart of FIG. 5, and when the release is not completed, the determination in S203 is repeated until the release is completed.

移 Move to the explanation based on the time chart. 7 and 9 show the operation of the drive unit S by the mode switching control according to the present embodiment. FIG. 7 shows the operation at the time of switching from the series hybrid mode to the engine direct connection mode, and FIG. Operations at the time of switching to the series hybrid mode are shown respectively. FIG. 8 shows an operation according to a comparative example when switching from the series hybrid mode to the engine direct mode. 7 to 9 show, among the rotation speed N and the torque Trq, those of the engine 1 by a solid line, those of the generator motor 2 by a dotted line, those of the traveling motor 3 by a two-dot chain line, and the output of the drive system S. That is, the rotation speed and torque of the drive shaft 6 are indicated by a particularly thick solid line.

At the time of switching from the series hybrid mode to the engine direct connection mode (FIG. 7), after determining that the mode is being switched (time t11), the rotation synchronization control for the clutch c1, which is the engagement side clutch, is started (rotation synchronization phase Psyn). ). Specifically, a torque Trqmg1 is generated by the power generation motor 2 to increase the rotation speed Nmg1 of the power generation motor and the rotation speed (engine speed) Neng of the engine 1 which is the driving source after the mode switching, and the rotation speed Nmg1 of the power generation motor Nmg1. Closer to the output rotation speed Nout corresponding to the rotation speed of the drive shaft 6. The state in which the difference ΔN (= Nout−Nmg1) between the output rotation speed Nout and the power generation motor rotation speed Nmg1 decreases to a predetermined value or the rotation speed difference ΔN is equal to or less than a predetermined value for a predetermined period of time. If continued (time t21), it is determined that the rotation synchronization has been completed, and the process shifts to the clutch engagement phase Pegm to engage the clutch c1. When the engagement of the clutch c1 is completed (time t31), the process proceeds to the torque replacement phase Pswt. Here, from the rotation synchronization phase Psyn to the clutch engagement phase Pegm, the state in which the clutch c2 as the disengagement side clutch is engaged is maintained, and in the torque change phase Pswt, the state in which both the clutches c1 and c2 are engaged is formed. Is done. In the present embodiment, a command to release the clutch c2 is output at the same time as the transition to the torque change phase Pswt (time t31). In the torque replacement phase Pswt, the torque Trqeng of the engine 1 is increased while the torque Trqmg2 of the traveling motor 3 is decreased while the torque applied to the drive shaft 6, that is, the total drive torque Trqttl of the vehicle is kept constant. Then, it is determined that the torque switching has been completed when the torque Trqeng of the engine 1 matches the total drive torque Trqttl or the torque Trqmg2 of the traveling motor 3 has decreased to 0 (time t41), and the clutch c2 After release, the mode switching control ends (time 51).

同様 The same applies when switching from the direct engine mode to the series hybrid mode (FIG. 9). After it is determined that the mode is being switched (time t13), the rotation synchronization control for the clutch c2, which is the engagement side clutch, is started, and the traveling motor 3 generates the torque Trqmg2 to increase the traveling motor rotation speed Nmg2. Near the output rotation speed Nout. The state in which the difference ΔN (= Nout−Nmg2) between the output rotation speed Nout and the traveling motor rotation speed Nmg2 decreases to a predetermined value or the rotation speed difference ΔN is equal to or less than a predetermined value for a predetermined period of time. If continued (time t23), it is determined that the rotation synchronization has been completed, and the process shifts to the clutch engagement phase Pegm to engage the clutch c2. When the engagement of the clutch c2 is completed (time t33), the process proceeds to the torque replacement phase Pswt, and the torque Trqmg2 of the traveling motor 3 is increased while the total driving torque Trqttl of the vehicle is kept constant, and the torque Trqeng of the engine 1 is reduced. Let it. In the same manner as in the transition to the direct engine connection mode described above, the state in which the clutch c1 as the disengagement side clutch is engaged is maintained from the rotation synchronization phase Psyn to the clutch engagement phase Pegm. A state where both c1 and c2 are fastened is formed. At the same time as the shift to the torque transfer phase Pswt (time t33), the command to release the clutch c1 is output in the same manner as described above. Then, it is determined that the torque switching has been completed when the torque Trqmg2 of the traveling motor 3 matches the total drive torque Trqttl or the torque Trqeng of the engine 1 has decreased to 0 (time t43), and the clutch c1 After the release, the mode switching control ends (time 53).

FIG. 8 shows the operation when the engagement of the clutch c1 and the release of the clutch c2 are started simultaneously at the time of switching from the series hybrid mode to the direct engine connection mode as a comparative example.

(4) After the determination that the mode switching is being performed (time t12), the rotation synchronization for the clutch c1 and the decrease in the motor torque Trqmg2 for the purpose of releasing the clutch c2 are simultaneously started. Here, since it takes a certain time to sufficiently bring the generator motor speed Nmg1 close to the output speed Nout, the clutch c2 is released first (time t22), and subsequently the rotation synchronization is achieved (time t22). At t32), the clutch c1 is engaged (time t42).

Then, in the comparative example, in a period PRDn from the time t22 when the clutch c2 is released to the time t42 when the engagement of the clutch c1 is completed, both the clutches c1 and c2 are released, and the transmission of power to the drive wheels 7 is stopped. Since no state, that is, a so-called neutral state is formed, drivability is impaired. This is a problem that is similarly valid when switching from the engine direct connection mode to the series hybrid mode.

On the other hand, in the present embodiment, after the clutch on the engagement side is engaged, the torque is changed in a state where both the clutches c1 and c2 are engaged, and the clutch on the release side is disengaged. The drive system S is prevented from entering a neutral state throughout the switching period.

(Explanation of effects)
The drive system S for an electric vehicle according to the present embodiment is configured as described above, and effects obtained by the present embodiment will be described below.

First, a clutch c1 is interposed on a power transmission path connecting the engine 1 and the drive wheels 7 so that the connection between the engine 1 and the drive wheels 7 can be cut off. A clutch c2 is interposed on the power transmission path to be connected, so that the connection between the traveling motor 3 and the driving wheels 7 can be cut off. Thus, during traveling in the series hybrid mode, the clutch c1 is released to prevent the engine 1 and the generator motor 2 from being driven together, and during traveling in the direct engine mode, the clutch c2 is released to travel. It is possible to avoid the motor 3 from being rotated. Thus, it is possible to construct an efficient drive system S that suppresses a decrease in electric cost.

Then, at the time of mode switching, the process shifts to the torque change phase after the engagement side clutch is engaged, and the torque is changed while both clutches c1 and c2 are engaged, so that when the mode is switched, It is possible to prevent the drive system S from entering the neutral state, and to perform the switching more appropriately. Here, since the clutches c1 and c2 are both engaged when the torque is changed, the reduction of the torque on the disengagement side and the increase of the torque on the engagement side are performed by keeping the total drive torque Trqttl constant. It is possible to perform while maintaining, and it is possible to suppress deterioration of drivability, and to maintain drivability before and after mode switching.

Second, after the clutch is engaged, the torque of the drive source before the mode switching (for example, at the time of mode switching from the series hybrid mode to the engine direct mode, before the torque Trqmg2 of the traveling motor 3) decreases to zero before the mode switching. In the embodiment, at the same time that the torque of the traveling motor 3 starts to be decreased, a command to release the clutch is output to the disengagement side clutch. This makes it possible to release the clutch immediately after the torque reaches 0 on the release side, and to suppress the deterioration in efficiency due to the co-rotation.

Third, the adoption of a meshing clutch, particularly a dog clutch, for the clutches c1 and c2 makes it possible to construct a more efficient system by reducing weight while reducing costs.

(Description of Another Embodiment)
Another embodiment of the present invention will be described below.

FIG. 10 is a flowchart showing the content of the processing in the torque change phase of the mode switching control according to another embodiment of the present invention.

The configuration of the drive system S according to the present embodiment may be the same as that shown in FIG. 1, and the overall flow of the mode switching control may be the same as that shown in FIG.

In the flowchart shown in FIG. 10, in S301, a command to release the clutch on the release side is output. For example, a command to operate the clutch actuator in a direction to release the clutch is output.

In steps S302 to S304, control for changing the torque between the engagement side and the release side is executed. In the change of the torque according to the present embodiment, the torque transmitted to the drive wheels 7 via the release-side clutch is reduced to 0 over a predetermined time (hereinafter, referred to as “target change time”), The reduced torque is embodied as a control that compensates for the increased torque by increasing the torque transmitted to the drive wheels 7 via the clutch on the engagement side. For convenience of explanation, the case of switching from the series hybrid mode to the engine direct connection mode will be described.

In S302, a command torque Tcmd_mg2 for the traveling motor 3 is calculated. The traveling motor command torque Tcmd_mg2 is set to the smaller one of the replacement calculated torque Tcal_mg2 calculated by the following equation (1.1) and the post-switch target torque Ttrg_mg2. The post-switch target torque Ttrg_mg2 can be set based on the operating state of the vehicle, such as the accelerator opening APO and the vehicle speed VSP.

Tcal_mg2 = (Ttrg_mg2-Tcal_mg2 _n-1 ) / (tswt-t) + Tcal_mg2 _n-1 (1.1)
In the above equation (1.1), Tcal_mg2 _n-1 is the previous value of the calculated torque at the time of transfer, tswt is the target transfer time, and t is the elapsed time since the start of the transfer. is there.

In S303, the command torque Tcmd_eng for the engine 1 is calculated. The engine command torque Tcmd_eng is set to the smaller one of the replacement calculated torque Tcal_eng calculated by the following equation (1.2) and the post-switch target torque Ttrg_eng. The post-switch target torque Ttrg_eng can be set based on the driving state of the vehicle.

Tcal_eng = (Ttrg_eng−Tcal_eng _n−1 ) / (tswt−t) + Tcal_eng _n−1 (1.2)
In the above equation (1.2), Tcal_eng _n-1 is the previous value of the calculated torque at the time of replacement.

In S304, a command torque Tcmd_mg1 for the generator motor 2 is calculated. The generation motor command torque Tcmd_mg1 is set to the smaller one of the replacement calculated torque Tcal_mg1 calculated by the following equation (1.3) and the post-switch target torque Ttrg_mg1. The post-switch target torque Ttrg_mg1 can be set based on the driving state of the vehicle.

Tcal_mg1 = Ttrg_ttl − {(Tcmd_mg2 × Rmg2 + Tcmd_eng × Reng) / Reng} × Rmg1 (1.3)
In the above equation (1.3), Ttrg_ttl is a target value of the total drive torque according to the driving state of the vehicle, Rmg1 is the gear ratio of the gear train Ga, and Rmg2 is the gear ratio of the gear train Gb. Yes, Reng is the gear ratio of the gear train Gc.

That is, the above equation (1.3) means that the shortage of the total torque of the traveling motor command torque Tcmd_mg2 and the engine command torque Tcmd_eng with respect to the total drive torque target value Ttrg_ttl is set to the generation motor command torque Tcmd_mg1. I do.

On the other hand, at the time of switching from the engine direct connection mode to the series hybrid mode, the shortage of the total torque of the generation motor command torque Tcmd_mg1 and the engine command torque Tcmd_eng with respect to the command value Tcmd_ttl of the total drive torque is converted to the traveling motor command torque Tcmd_mg2. Will be set. In this case, the calculated torque at the time of replacement can be calculated by the following equations (2.1) to (2.3).

Tcal_mg1 = (Ttrg_mg1-Tcal_mg1 _n-1 ) / (tswt-t) + Tcal_mg1 _n-1 (2.1)
Tcal_eng = (Ttrg_eng−Tcal_eng _n−1 ) / (tswt−t) + Tcal_eng _n−1 (2.2)
Tcal_mg2 = {Tcmd_ttl- (Tcmd_mg1 / Rmg1 + Tcmd_eng) × Reng} / Rmg2} (2.3)
In S305, it is determined whether or not the release of the clutch has been completed. When the release of the clutch is completed, the process returns to the basic routine shown in FIG. 5. When the release is not completed, the processes of S302 to 305 are repeated until the release is completed, and the switching of the torque is continued.

In S306, the command torque for each of the engine 1, the generator motor 2, and the traveling motor 3 is set to the post-switch target torque. That is, regardless of whether or not the change of the torque is completed, when the release of the clutch is completed, the command torque is set to the respective post-switch target torque immediately after the release of the clutch.

11 and 13 show the operation of the drive unit S by the mode switching control according to the present embodiment. FIG. 11 shows the operation at the time of switching from the series hybrid mode to the direct engine mode, and FIG. Operations at the time of switching to the series hybrid mode are shown respectively. FIG. 12 shows an operation according to a comparative example when switching from the series hybrid mode to the engine direct connection mode.

At the time of switching from the series hybrid mode to the direct engine connection mode (FIG. 11), after determining that the mode is being switched (time t14), the rotation synchronization control for the clutch c1, which is the engagement side clutch, is started (rotation synchronization phase Psyn). ). In the present embodiment, the generator motor rotation speed Nmg1 and the engine rotation speed Neng are increased by reducing the torque Trqmg1 for the regeneration by the generation motor 2, and the generation motor rotation speed Nmg1 is made closer to the output rotation speed Nout. Whether the difference ΔN (= Nout−Nmg1) between the output rotation speed Nout and the generation motor rotation speed Nmg1 decreases to a predetermined value (time t24), or the state where the rotation speed difference ΔN is equal to or smaller than a predetermined value If the operation has continued over time (time t34), it is determined that the rotation synchronization has been completed, and the process shifts to the clutch engagement phase Pegm to engage the clutch c1. In the torque change phase Pswt after the engagement of the clutch c1 is completed (time t44), the command torque Tcmd_eng for the engine 1, the power generation motor 2 and the traveling motor 3 is calculated by the above equations (1.1) to (1.3). Tcmd_mg1 and Tcmd_mg2 are calculated. In the present embodiment, the traveling motor command torque Tcmd_mg2 is reduced, and the reduced torque is supplemented by the power generation motor command torque Tcmd_mg1, so that the total drive torque does not become excessive or insufficient with respect to the target value Ttrg_ttl, and the torque is replaced. It is possible to achieve Here, if the accelerator pedal is depressed during the torque replacement phase Pswt, the target value Ttrg_ttl of the total drive torque increases accordingly (time t54), but the total drive torque becomes insufficient with respect to the target value Ttrg_ttl after the increase. The minute is eliminated by increasing the generator motor command torque Tcmd_mg1 by a torque corresponding to the shortage. Then, it is determined that the torque transfer has been completed when the target transfer time tswt has elapsed or the traveling motor command torque Tcmd_mg2 has decreased to 0 (time t64), and the mode switching is performed after the release of the clutch c2. The control ends (time 74).

同様 The same applies when switching from the engine direct mode to the series hybrid mode (FIG. 13). After it is determined that the mode is being switched (time t16), rotation synchronization control for the clutch c2, which is the clutch on the engagement side, is started, the traveling motor 3 generates a torque Trqmg2, and the traveling motor rotation speed Nmg2 is increased. Near the output rotation speed Nout. Whether the difference ΔN (= Nout−Nmg2) between the output rotation speed Nout and the traveling motor rotation speed Nmg2 decreases to a predetermined value (time t26) or the state where the rotation speed difference ΔN is equal to or less than a predetermined value If the operation continues over time (time t36), it is determined that the rotation synchronization has been completed, and the process shifts to the clutch engagement phase Pegm to engage the clutch c2. In the torque change phase Pswt after the engagement of the clutch c2 is completed (time t46), the command torque Tcmd_eng for the engine 1, the power generation motor 2 and the traveling motor 3 is calculated by the above equations (2.1) to (2.3). Tcmd_mg1 and Tcmd_mg2 are calculated. Specifically, the engine command torque Tcmd_eng is reduced, and the travel motor command torque Tcmd_mg2 is increased by the amount corresponding to the decrease. Here, when the accelerator pedal is depressed during the torque change phase Pswt, and the target value Ttrg_ttl of the total drive torque increases (time t56), the traveling motor is reduced by the shortage of the total drive torque with respect to the target value Ttrg_ttl after the increase. The command torque Tcmd_mg2 is increased. Then, when the engine command torque Tcmd_eng has decreased to 0, it is determined that the change of torque has been completed (time t66), and the mode switching control is terminated after releasing the clutch c1 (time 76).

FIG. 12 shows, as a comparative example, a case where switching from the series hybrid mode to the engine direct connection mode is performed, and when the accelerator opening APO increases in the torque switching phase Pswt, the torque is switched during the target switching time tswt. Are completed (steps t55 to t65) when the gradient of the change in the command torque Trqmg1 to the traveling motor 3 is increased in order to complete.

In the comparative example, the total value Trqttl of the command torques Trqeng, Trqmg1, and Trqmg2 does not follow the target value Ttrg_ttl of the total drive torque, as shown by a dashed line in comparison with the target value Ttrg_ttl of the total drive torque, and the total drive torque Tttl. Therefore, there is a concern that a quick response to depression of the accelerator pedal cannot be obtained, and that drivability is deteriorated.

On the other hand, according to the present embodiment, the total drive torque of the total value of the engine command torque Tcmd_eng, the generation motor command torque Tcmd_mg1, and the traveling motor command torque Tcmd_mg2 with respect to the increase in the accelerator opening APO in the torque replacement phase Pswt. Of the target value Ttrg_ttl by increasing the torque transmitted to the drive wheels 7 through the engagement-side clutch, it is possible to suppress the occurrence of the shortage, and to ensure the follow-up of torque control. In addition, deterioration of drivability can be suppressed.

Here, by increasing the torque transmitted to the drive wheels 7 through the clutch on the engagement side, one drive source that changes the command torque is used, and the controllability due to transient variations occurring in a plurality of drive sources is increased. Deterioration can be avoided.

Further, the torque corresponding to the shortage is generated by the electric motor (the power generation motor 2 when switching from the series hybrid mode to the engine direct-coupled motor), so that the response of the actual torque to the change in the command torque is ensured. Thus, higher controllability can be realized as compared with the case where the insufficient torque is generated by the engine 1.

FIG. 14 shows an example of the operation when the clutch is released before the torque change is completed (time t67), when switching from the series hybrid mode to the engine direct connection mode.

In this case, the command torques Tcmd_eng, Tcmd_mg1, and Tcmd_mg2 for the engine 1, the power generation motor 2, and the traveling motor 3 are set to the post-switching target torques Ttrg_eng, Ttrg_mg1, and Ttrg_mg2 immediately after the clutch is released. That is, in response to accidental or sudden release of the clutch c2, which is the clutch on the disengagement side, the torque transmitted to the drive wheels 7 through the clutch c1, which is the clutch on the engagement side, is increased to match the target value after switching. It is.

This suppresses a drop in the total drive torque Trqttl due to the release-side clutch being released in a state where the torque transmitted through the clutch still remains, and increases the total drive torque Trqttl before and after the clutch is released. Thus, it is possible to suppress the deterioration of drivability due to insufficient torque.

As described above, the embodiment of the present invention has been described. However, the above embodiment is only a part of the application example of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. It is not the purpose. Various changes and modifications can be made to the above embodiment within the scope of the matters described in the claims.

Claims

An internal combustion engine,
A power generation motor arranged to be capable of generating power by receiving the power of the internal combustion engine,
A traveling motor disposed so as to be driven by the electric power generated by the power generation motor,
With
The internal combustion engine and the drive wheels are connected and disconnected via a first clutch, while the traveling motor and the drive wheels are connected and disconnected via a second clutch different from the first clutch. A series hybrid mode in which the traveling motor is used as a driving source and the power of the traveling motor is transmitted to the driving wheels to travel, and at least one of the internal combustion engine and the power generation motor is used as a driving source and the driving is performed. A control method of an electric vehicle configured to be able to switch between an engine direct connection mode in which the power of a source is transmitted to the drive wheels and the vehicle runs.
At the time of mode switching for switching between the series hybrid mode and the engine direct connection mode,
Engaging both the first clutch and the second clutch,
While both the first and second clutches are engaged, the ratio of the torque of the internal combustion engine and the torque of the traveling motor to the total driving torque of the vehicle is increased toward the ratio after the mode switching. Change
Releasing or releasing the clutch on the release side of the first and second clutches when the ratio approaches or reaches the ratio after the mode switching;
An electric vehicle control method.
It is a control method of the electric vehicle of Claim 1, Comprising:
Setting the total drive torque according to the driving state of the vehicle,
The torque of the internal combustion engine and the torque of the traveling motor are transmitted to the drive wheels via the first clutch in the torque switching phase at the time of mode switching, which changes the ratio of the total drive torque to the drive torque. A total command torque obtained by adding a command value of the torque to the drive wheel via the second clutch to a command value of the torque transmitted to the drive wheels,
An electric vehicle control method.
It is a control method of the electric vehicle of Claim 2, Comprising:
In the torque change phase, the command value of the torque transmitted to the drive wheels via the engagement-side clutch among the first and second clutches is increased with respect to the change in the total drive torque, Matching the total command torque with the total drive torque after the increase,
An electric vehicle control method.
It is a control method of the electric vehicle of Claim 3, Comprising:
When switching from the series hybrid mode to the engine direct mode, a torque corresponding to the increase in the total drive torque is generated by the power generation motor, and when switching from the engine direct mode to the series hybrid mode, the total drive torque is increased. Causing the traveling motor to generate a torque corresponding to the increased torque,
An electric vehicle control method.
The control method for an electric vehicle according to any one of claims 1 to 4, wherein
The first and second clutches are both dog clutches.
An electric vehicle control method.
It is a control method of the electric vehicle of Claim 5, Comprising:
Reducing the fastening force acting in the direction of pressing the driving element and the driven element against the disengagement side clutch before the torque of the driving source before the mode switching reaches 0,
An electric vehicle control method.
It is a control method of the electric vehicle of Claim 5 or 6, Comprising:
When the clutch on the release side is released before the ratio of the torque of the internal combustion engine and the traveling motor reaches the ratio after the mode switching, immediately after the release, the ratio of the torque is changed to the ratio after the mode switching. To match,
An electric vehicle control method.
An internal combustion engine,
A power generation motor arranged to be capable of generating power by receiving the power of the internal combustion engine,
A traveling motor disposed so as to be driven by the electric power generated by the power generation motor,
A first clutch interposed in a first power transmission path connecting the internal combustion engine and driving wheels;
A second clutch interposed in a second power transmission path different from the first power transmission path, connecting the traveling motor and the drive wheels;
A controller,
With
The controller is
A series hybrid mode in which the travel motor travels with power transmitted to the drive wheels through the second power transmission path; and at least one of the internal combustion engine and the power generation motor as a drive source, and In both the engine direct drive mode and running with power transmitted to the drive wheels through a power transmission path, set the total drive torque according to the driving state of the vehicle,
At the time of mode switching for switching between the series hybrid mode and the engine direct connection mode,
Engaging both the first clutch and the second clutch,
While both of the first and second clutches are engaged, the ratio of the torque of the internal combustion engine and the torque of the traveling motor to the total drive torque of the vehicle is increased toward the ratio after the mode switching. Change
Releasing or releasing the clutch on the release side of the first and second clutches when the ratio approaches or reaches the ratio after the mode switching;
Drive system for electric vehicles.