JP2020131880A - Control method for electric vehicle and drive system of electric vehicle - Google Patents

Abstract

To more satisfactorily perform switching between a series hybrid mode and an engine direct connection mode.SOLUTION: An electric vehicle includes an internal combustion engine, a power generation motor, and a traveling motor, has a first clutch for connecting the internal combustion engine to drive wheels, and is configured to be capable of switching between a series hybrid mode and an engine direct connection mode, in which in the series hybrid mode, the first clutch is released, and in the engine direct connection mode, the first clutch is engaged. In the electric vehicle, during mode switching to switch from the engine direct connection mode to the series hybrid mode, power generation of the power generation motor using the internal combustion engine as a power source is not performed, total torque generated by the internal combustion engine and the power generation motor is reduced, and the first clutch is released when the total torque reaches 0 Nm or becomes equal to or less than a predetermined value near 0 Nm.SELECTED DRAWING: Figure 8

Description

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

A series hybrid type drive system is known in which a generator is driven by the power of an internal combustion engine, and an electric motor for traveling (hereinafter referred to as a "travel motor") is operated by the electric power generated by the generator. ing. Patent Document 1 describes such a drive system in which an internal combustion engine and drive wheels are connected via a clutch so that the power of the internal combustion engine can be transmitted to the drive wheels without a traveling motor. Is disclosed.

Patent Document 1 further states that, as a control when switching from the engine direct connection mode to the series hybrid mode using the traveling motor as the drive source, the output of the engine before the switching is maintained, and the output of the engine is transferred to the drive wheels. The ratio of the electric transmission consumed for driving the generator to the amount consumed for the mechanical transmission of the machine was increased, the mechanical transmission reached 0, and the output of the generator became equal to the output of the engine. At this point, it is disclosed to release the clutch.

International Publication No. 2011/074483 (Fig. 1, paragraphs 0037 and 0038)

However, according to the technique described in Patent Document 1, maintaining the output of the engine during torque replacement itself may be a problem. For example, after shifting to the series hybrid mode, the engine is still running when the torque replacement is completed, even though we want to carry out so-called EV driving, in which only the traveling motor is driven to drive without driving the engine. Since the output is maintained, the transition to EV driving is not performed with sufficient smoothness.

Furthermore, under the condition that the power generation by the generator is restricted, the ratio of the electric transmission portion to the output of the engine cannot be increased, and the switching from the engine direct connection mode to the series hybrid mode cannot be performed. There is. As a condition for limiting the power generation by the generator, the generator generates surplus power with respect to the required output of the system, but the battery is already in a high charge state, and the surplus power is used to charge the battery. It is possible to exemplify the case where it cannot be applied to. Power generation by the generator is restricted to avoid overcharging the battery.

In view of the above problems, it is an object of the present invention to provide an electric vehicle control method and an electric vehicle drive system that enable better switching between the series hybrid mode and the engine direct connection mode.

In one embodiment of the present invention, a hybrid drive system for transmitting driving force to the drive wheels of a vehicle is provided, and the hybrid drive system includes an internal combustion engine, a power generation motor arranged so as to be able to generate power by receiving power from the internal combustion engine, A series hybrid mode that includes a traveling motor that is arranged so as to be driveable by the electric power generated by the power generation motor, has a first clutch that connects the internal combustion engine and the drive wheels, and uses the traveling motor as a drive source. An engine direct connection mode and a control method for an electric vehicle configured to be switchable are provided. In the series hybrid mode, the first clutch is released, and in the engine direct connection mode, the first clutch is engaged. In this embodiment, when the mode is switched from the direct engine connection mode to the series hybrid mode, the power generation motor powered by the internal combustion engine does not generate power, and the total torque generated by the internal combustion engine and the power generation motor is reduced to increase the total torque. When it reaches 0 Nm or becomes a predetermined value close to 0 Nm or less, the first clutch is released.

In other forms, an electric vehicle drive system is provided.

According to the present invention, when the mode is switched from the engine direct connection mode to the series hybrid mode, the torque is replaced between the internal combustion engine and the traction motor without generating the power generation motor, in other words, the power generation motor. This makes it possible to achieve this without generating regenerative torque. Therefore, the range of options for torque replacement is expanded, and it is possible to realize appropriate replacement according to the situation, and from the engine direct connection mode to the series hybrid mode regardless of the conditions related to the possibility of power generation. Since the switching can be performed, it is possible to satisfactorily switch the traveling mode.

FIG. 1 is a schematic view 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 the operation of the drive system according to the same embodiment in the series hybrid mode. FIG. 3 is an explanatory diagram showing the operation of the drive system according to the same embodiment in the engine direct connection mode. FIG. 4 is an explanatory diagram showing a traveling mode of the drive system according to the same embodiment according to the operating region. FIG. 5 is a flowchart showing a flow of mode switching determination according to the same embodiment. FIG. 6 is a flowchart showing the overall flow of the mode switching control according to the same embodiment. FIG. 7 is a flowchart showing the contents of the process (A) in the torque replacement phase of the mode switching control according to the same embodiment. FIG. 8 is an explanatory diagram showing the operation of the drive system according to the embodiment of the present invention when the mode is switched from the engine direct connection mode to the series hybrid mode. FIG. 9 is an explanatory diagram showing an operation according to a comparative example when the mode is switched from the engine direct connection mode to the series hybrid mode. FIG. 10 is an explanatory diagram showing an operation according to a modified example of the drive system according to the embodiment of the present invention when the mode is switched from the engine direct connection mode to the series hybrid mode. FIG. 11 is a flowchart showing the contents of processing in the torque replacement phase of the mode switching control according to another embodiment of the present invention. FIG. 12 is a flowchart showing a flow of mode switching determination according to still another embodiment of the present invention. FIG. 13 is an explanatory diagram showing switching of the traveling mode (engine direct connection permission map, engine direct connection prohibition map) according to the system state.

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

(Overall configuration of drive system)
FIG. 1 shows the overall configuration of a hybrid drive system (hereinafter, also referred to as “drive system”, sometimes simply referred to as “system”) S of an electric vehicle according to an embodiment of the present invention.

The drive system S according to the present embodiment is mounted on an electric vehicle to form a propulsion device for the vehicle. The drive system S includes an internal combustion engine (hereinafter, simply referred to as “engine”) 1, an electric motor for power generation (hereinafter, referred to as “power generation motor”) 2, and an electric motor for traveling (hereinafter, referred to as “travel motor”) 3. , Equipped with. The term "for power generation" or "for traveling" here merely refers to its main role in the drive system S, and causes the power generation motor 2 to bear a part of the driving force formation or controls the traveling motor 3. Of course, it is possible to bear a part of the power regeneration.

The output shaft or crankshaft 11 of the engine 1 is connected to the rotating shaft 21 of the power generation motor 2 via a gear train Ga composed of a plurality of gears. The torque of the engine 1 is transmitted to the power generation motor 2 at a predetermined gear ratio through the gear train Ga to operate the power generation motor 2. In the present embodiment, the connection between the engine 1 and the power generation motor 2 via the gear train Ga is permanent and cannot be cut off.

The power generation motor 2 is electrically connected to the traveling motor 3 and is also connected to the battery 4, and supplies the electric power generated by receiving the power supply from the engine 1 to the traveling motor 3 or the battery 4. To do. The supply of electric power from the power generation motor 2 to the traveling motor 3 and the supply of electric power from the power generation motor 2 to the battery 4 can be executed according to the operating state of the vehicle, the charging state of the battery 4, and the like. FIG. 1 schematically shows an electrical connection between a power generation motor 2, a traveling motor 3, and a battery 4 by an alternate long and short dash line.

The traveling motor 3 is electrically connected to the battery 4, and its rotating shaft 31 is connected to the ring gear of the differential 5 via a gear train Gb composed of 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 and 6 via the differential 5 to rotate the drive wheels 7 and rotate the vehicle. Promote. In the present embodiment, the traveling motor 3 is composed of a motor generator that can operate not only as a generator but also as an electric motor, propels the vehicle, and receives power from the drive wheels 7 via the gear train Gb. , It is also possible to generate electricity. It is possible to supply the electric power generated by the traveling motor 3 to the battery 4 and use it 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 composed of 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 distributed to the left and right drive shafts 6 and 6 via the differential 5, so that the drive wheels 7 are rotated and the vehicle is propelled. Will be done.

In the present embodiment, clutches c1 and c2 are interposed in the gear train Gc and the gear train Gb, respectively, and the engine 1 and the drive wheel 7 are connected via the gear train Gc, and the traveling motor 3 and the drive wheel 7 are connected. The connection via the gear train Gb is configured to be cut off by the clutches c1 and c2, respectively. The clutches c1 and c2 may be meshing clutches, and a dog clutch can be exemplified as applicable to the clutches c1 and c2. In the present embodiment, a dock clutch is used as the clutches c1 and c2.

In the clutch (hereinafter sometimes referred to as "engine side clutch") c1 provided in the gear train Gc, one of the clutch elements or the meshing element cannot rotate relative to the output shaft 11 of the engine 1, so that the clutch element or the meshing element cannot rotate on the output shaft 11. It is configured to be slidable, which engages with the other clutch element or meshing element provided on the gear coaxially arranged with the output shaft 11 to allow power transmission via the gear train Gc.

Similarly, in the clutch (hereinafter, may be referred to as “motor side clutch”) c2 provided in the gear train Gb, one of the clutch elements or the meshing element cannot rotate relative to the rotation shaft 31 of the traveling motor 3, and this rotation occurs. It is configured to be slidable on the shaft 31, and by engaging with the other clutch element or meshing element provided on the gear coaxially arranged with the rotating shaft 31, power can be transmitted via the gear train Gb. And.

The clutch provided in the gear train Gc on the engine 1 side, that is, the engine side clutch c1, constitutes the "first clutch" according to the present embodiment, and the clutch provided in the gear train Gb on the traveling motor 3 side, that is, the motor. The side clutch c2 constitutes the "second clutch" according to the present embodiment.

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

(Basic configuration of control system)
Information on 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 by the driver (hereinafter referred to as "accelerator opening") APO, a signal indicating the running speed of the vehicle (hereinafter referred to as "vehicle speed") VSP, and the rotation speed Neng of the engine 1 are used. A signal indicating, a signal indicating the rotation speed Nmg1 of the power generation motor 2, and a signal indicating the rotation speed Nmg2 of the traveling motor 3 are input to the controller 101. Then, in order to detect various parameters, the accelerator opening sensor 201 that detects the accelerator opening APO, the vehicle speed sensor 202 that detects the vehicle speed VSP, and the rotation speed Neng of the engine 1 are set to the rotation speed per unit time (hereinafter, "engine rotation speed"). ”), The engine speed sensor 203 that detects the rotation speed Nmg1 of the power generation motor 2 as the power generation motor speed sensor 204, and the travel speed Nmg2 that detects the rotation speed Nmg2 of the travel motor 3 as the travel speed. A motor rotation speed sensor 205 is provided.

The controller 101 executes predetermined calculations based on various input signals to control the operations of the engine 1, the power generation motor 2, and the traveling motor 3, and also controls the states of the clutches c1 and c2.

(Basic operation of drive system)
In the present embodiment, it is possible to switch the driving mode between the series hybrid mode and the engine direct connection mode during actual driving. In the series hybrid mode, the traveling motor 3 is used as the drive source of the vehicle, and in the engine direct connection mode, the engine 1 is basically used as the drive source of the vehicle.

2 and 3 show the operation of the drive system S according to the traveling mode, 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 power is transmitted by a thick dotted line with an arrow, and the arrow indicates the direction in which power is transmitted.

In the series hybrid mode, as shown in FIG. 2, while the clutch c1 is released, the clutch c2 is engaged so that the torque of the engine 1 can be transmitted to the power generation motor 2 through the gear train Ga and the torque of the traveling motor 3. 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 while 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. When the power generation motor 2 has not only the function of a generator but also the function of an electric motor, it is possible to generate torque by the power generation motor 2 and transmit the torque to the drive wheels 7 through the gear trains Ga and Gc.

In the present embodiment, in the engine direct connection mode, the transmission of power between the traveling motor 3 and the driving wheels 7 is cut off by releasing the clutch c2 on the power transmission path connecting the traveling motor 3 and the driving wheels 7. , It is avoided that the traveling motor 3 is rotated with the rotation of the drive wheels 7. However, the clutch c2 may be engaged as well as released. As a result, in addition to the torque of the engine 1, the torque of the traveling motor 3 can be transmitted to the drive wheels 7. In the case of the engine direct connection mode, the clutch c2 may be engaged or released depending on the situation.

(Control related to mode switching)
Switching between the series hybrid mode and the engine direct connection mode is executed by switching the engagement and disengagement states of the clutches c1 and c2 based on the signal from the controller 101.

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

In the present embodiment, a mode selection map in which the driving mode for each driving area is defined is created in advance, and this is stored in the controller 101. Roughly speaking, the engine direct connection mode is selected in the high speed range, and the series hybrid mode is selected in the other areas. In the present embodiment, the engine direct connection mode is selected in the high-speed region B in which the load is relatively low, and the series hybrid mode is selected in the other regions A. The controller 101 refers to the mode selection map based on the vehicle speed VSP and the accelerator opening APO, determines the driving areas A and B to which the driving state of the vehicle belongs, and switches the traveling mode according to the determination result.

The control related to the switching of the traveling mode (hereinafter referred to as “mode switching control”) will be described below. After explaining the overall flow with reference to the flowchart, a more specific explanation will be given with reference to the time chart.

FIG. 5 shows the flow of the process of determining whether or not to execute the mode switching control (hereinafter referred to as “mode switching determination”), and FIG. 6 shows the mode switching control at the time of switching from the engine direct connection mode to the series hybrid mode. It shows the overall flow of. FIG. 7 shows the content of the process (A) in the torque replacement phase in the mode switching control. In the present embodiment, the controller 101 is programmed to execute the mode switching determination at a predetermined cycle and execute the mode switching control when the mode is switched.

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

In S102, it is determined whether or not the mode is switched. Specifically, has the driving state of the vehicle determined by the accelerator opening APO and the vehicle speed VSP shifted from the area A in the series hybrid mode to the area B in the engine direct connection mode among the driving areas A and B shown in FIG. Or conversely, it is determined whether or not the area B has moved to the area A. If the operation state shifts between the operation areas A and B and the mode is switched, the process proceeds to S103, and if the mode is not switched, the control by the current routine ends.

In S103, the mode switching control is executed.

Moving on to the flowchart shown in FIG. 6, in S201, whether or not the switching of the driving mode is the switching from the engine direct connection mode to the series hybrid mode, in other words, the transition of the operating region is the transition from the region B to the region A. Determine if it exists. In the case of switching to the series hybrid mode, the process proceeds to S202, and in the case of switching from the series hybrid mode to the engine direct connection mode instead of switching to the series hybrid mode, the control by this routine is terminated. FIG. 4 shows how the operating state shifts from the region B in the engine direct connection mode to the region A in the series hybrid mode by arrows a1 to a4.

In S202, control (hereinafter referred to as “rotational synchronization control”) for matching the rotational speeds of the driving element and the driven element with respect to the clutch on the engaging side is started. Here, the clutch on the engagement side means a clutch that is engaged after the mode is switched, and when switching from the engine direct connection mode to the series hybrid mode, the clutch (that is, the motor side clutch) c2 provided in the gear train Gb corresponds to the clutch. .. Then, as the rotation synchronization control in this case, torque is generated by the traveling motor 3 to increase the traveling motor rotation speed Nmg2.

In S203, it is determined whether or not the rotation synchronization is completed. This determination is performed, for example, depending on whether or not the difference in rotational speed between the driving element and the driven element of the clutch c2 is reduced to a predetermined value, and it is determined that the rotation synchronization is completed when the difference is reduced to a predetermined value. .. If the rotation synchronization is completed, the process proceeds to S204, and if it is not completed, the determination in S203 is repeated.

In S204, a command for engaging the motor-side clutch c2, which is the engagement-side clutch, is output. When the clutches c1 and c2 convert the operation of an actuator (for example, a servo type electric motor) into the movement of a driving element or a driven element via a link mechanism including a cam and a lever, the actuator is used. On the other hand, a command to operate in the direction of engaging the clutch is output.

In S205, it is determined whether or not the engagement of the clutch c2 is completed. This determination can be made, for example, by whether or not the actuators of the clutches c1 and c2 (specifically, the movable portion thereof) have reached the target position at the time of engagement. When the engagement of the clutch c2 is completed, the process of the torque replacement phase is executed, so the process proceeds to S301 in the flowchart shown in FIG. 7, and if not completed, the determination of S205 is repeated.

In S206, it is determined that the switching of the traveling mode is completed, and then the control by the current routine is terminated.

Moving on to the flowchart shown in FIG. 7, in S301, control for switching torque between the drive source before the mode switching and the drive source after the mode switching is started. In the present embodiment, when switching from the engine direct connection mode to the series hybrid mode, the power generation motor 2 using the engine 1 as a power source does not generate power, and the total torque generated by the engine 1 and the power generation motor 2 is reduced toward 0 Nm. Let me. In other words, "does not generate power from the power generation motor 2" means that the power generation motor 2 does not generate regenerative torque. In addition to the case where the power generation motor 2 performs power running, the power generation and power running of the power generation motor 2 Including the case where neither is performed. When the power generation motor 2 is forced to run, the battery 2 discharges the power. Specifically, when the driving force is generated only by the engine 1 before the mode switching, the torque of the engine 1 is reduced while maintaining the torque of the power generation motor 2 at 0 Nm, and the traveling motor 3 responds accordingly. To increase the torque of. Further, when the torque is generated by the power generation motor 2 in addition to the engine 1 before the mode switching, the total torque generated by the engine 1 and the power generation motor 2 is reduced, and the torque of the traveling motor 3 is correspondingly reduced. To increase. In order to reduce the total torque, it is possible to simultaneously reduce the torque of the engine 1 and the torque of the power generation motor 2 toward 0 Nm.

In S302, it is determined whether or not the torque replacement is completed. For example, it is determined whether or not the total torque generated by the engine 1 and the power generation motor 2 has reached 0 Nm, and when it reaches 0 Nm, it is determined that the torque replacement has been completed. When the torque replacement is completed, the process proceeds to S303, and when the torque replacement is not completed, the determination of S302 is repeated. The determination of whether or not the torque replacement is completed is not limited to this, and is based on determining whether or not the total torque is equal to or less than a predetermined value close to 0 Nm (however, larger than 0 Nm). It is also possible. When the total torque is equal to or less than this predetermined value, it is determined that the torque replacement is completed.

In S303, a command to release the clutch on the release side is output. For example, a command for operating the actuators of the clutches c1 and c2 in the direction of releasing the clutch is output. Here, the clutch on the release side means a clutch that is released after the mode is switched, and when switching from the engine direct connection mode to the series hybrid mode, the clutch provided in the gear train Gc (that is, the engine side clutch) c1 corresponds. ..

In S304, it is determined whether or not the release of the clutch c1 is completed. This determination can be made, for example, by whether or not the actuators of the clutches c1 and c2 (specifically, their movable parts) have reached the target position at the time of release. When the release of the clutch c1 is completed, the process returns to the flowchart shown in FIG. 6, and if it is not completed, the determination of S304 is repeated.

In the present embodiment, when the torque replacement is completed and the torque applied to the input shaft of the engine-side clutch c1 (that is, the on-shaft torque) reaches a predetermined value close to 0 Nm or 0 Nm, a release command for the clutch c1 is output. It was decided to. However, before the torque replacement is completed, in other words, before the shaft torque of the engine side clutch c1 reaches 0 Nm or a predetermined value, a release command is output in advance and the shaft torque reaches 0 Nm or a predetermined value. It is also possible to configure the clutch c1 to be released at that time. Such a mechanism is realized by, for example, interposing a means (for example, a spring) for urging the clutch elements of the dog clutch in a direction in which they are separated from each other when the dog clutch is adopted as the clutch c1. It is possible.

Let's move on to the explanation using the time chart. FIG. 8 shows the operation of the drive unit S at the time of switching from the engine direct connection mode to the series hybrid mode by the mode switching control according to the present embodiment. FIG. 8 (the same applies to FIGS. 9 and 10 described later) shows the rotation speed N and the torque Trq of the engine 1 by the solid line, the power generation motor 2 by the alternate long and short dash line, and the traveling motor 3. Are shown by dotted lines.

In the time chart shown in FIG. 8, after it is determined that the mode is being switched from the engine direct connection mode to the series hybrid mode (time t11), the rotation synchronization control for the motor side clutch c2 is started (rotation synchronization phase Psin), and the traveling motor 3 The torque Trqmg2 is generated to increase the traveling motor rotation speed Nmg2, and bring this closer to the output rotation speed Nout corresponding to the rotation speed of the drive shaft 6. When the difference ΔN (= Nut-Nmg2) between the output rotation speed Nut and the traveling motor rotation speed Nmg2 decreases to a predetermined value (time t21), it is assumed that the rotation synchronization is completed, and the clutch engagement phase Pegm is entered and the motor The side clutch c2 is engaged. In the clutch engagement phase Pegm, the torque Trqmg2 of the traveling motor 3 is reduced to 0. When the engagement of the motor-side clutch c2 is completed (time t31), the torque replacement phase Pswt is entered, and the torque transmitted to the drive wheels 7 through the engine-side clutch c1 is reduced, while the torque transmitted to the drive wheels 7 is reduced accordingly. Increases the torque transmitted to the drive wheels 7. Specifically, while reducing the total torque (= Trqeng + Trqmg1) generated by the engine 1 and the power generation motor 2 at a predetermined reduction rate ΔTdec, the torque Trqmg2 of the traveling motor 3 is reduced at a predetermined increase rate ΔTinc according to the reduction rate ΔTdec. Increase. In the present embodiment, both the torque Trqeng of the engine 1 and the torque Trqmg1 of the power generation motor 2 are simultaneously reduced toward 0. Then, after the total torque reaches 0, the engine 1 is shifted to an operation in which the torque Trqeng is 0 Nm (hereinafter referred to as “0 Nm operation”), and the torque Trqmg1 output by the power generation motor 2 is set to 0 Nm. In the present embodiment, the decrease rate ΔTdec of the total torque and the increase rate ΔTinc of the motor torque Trqmg2 are set to equal values. Then, when the total torque reaches 0, it is determined that the torque replacement is completed (time t41), a command to release the engine side clutch c1 is output, and the mode is switched after waiting for the engine side clutch c1 to be released. The control ends (time t51).

In the present embodiment, after the total torque reaches 0 Nm, the engine 1 is shifted to 0 Nm operation, the torque Trqmg1 output by the power generation motor 2 is set to 0 Nm, and after the engine side clutch c1 is released, the engine 1 and the power generation motor 2 are released. It was decided to stop the rotation of the engine (Neng = 0, Nmg1 = 0), but not limited to this, after the total torque reaches 0 Nm, the engine 1 is shifted to idle operation, and even after the engine side clutch c1 is released. The engine 1 and the power generation motor 2 may each maintain a rotation speed corresponding to idling.

FIG. 9 shows an operation according to a comparative example when switching from the engine direct connection mode to the series hybrid mode. In the comparative example, when the torque replacement phase Pswt is entered after the motor side clutch c2 is engaged, the torque Trqeng of the engine 1 is maintained at the torque before the mode switching, while the regenerative torque Trqmg1 (<0) is maintained by the power generation motor 2. To bring the total torque close to 0. It is assumed that the torque replacement is completed when the absolute value of the regenerative torque (= | Trqmg1 |) becomes equal to the engine torque Trqeng (time t41), and the release of the engine side clutch c1 is started. When the torque capacity of the engine-side clutch c1 decreases, the engine torque Trqeng decreases as the engine speed Neng increases, and the regenerative torque Trqmg1 of the power generation motor 2 also decreases (time t51).

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

First, when switching the mode from the engine direct connection mode to the series hybrid mode, the torque is replaced between the engine 1 and the traveling motor 3 without generating power from the power generation motor 2 powered by the engine 1. In other words, it can be achieved without generating a regenerative torque by the power generation motor 2. Therefore, not only the range of options for the method of simply replacing the torque is expanded, but also the appropriate replacement according to the situation can be realized. For example, when it is desired to carry out EV driving after shifting to the series hybrid mode. Since the output of the engine 1 can be extinguished by the time the torque replacement is completed (time t51 shown in FIG. 8), the transition to EV driving can be smoothly achieved.

Further, it is possible to switch from the engine direct connection mode to the series hybrid mode regardless of the conditions related to the possibility of power generation. In the case of the method of causing the power generation motor 2 to generate power to generate regenerative torque (FIG. 9), the electric power generated by this method is used to charge the battery 4, but the battery 4 is already in a high charging state. This is because if the electric power cannot be used to charge the battery 4, forcibly generating electricity may cause overcharging of the battery 4. According to the present embodiment, it is possible to switch from the engine direct connection mode to the series hybrid mode even in such a situation.

Second, when the mode is switched, the engine 1 is shifted to 0 Nm operation, and the torque output by the power generation motor is set to 0 Nm at the same time, so that the shock generated when the engine side clutch c1 is released is suppressed and smooth switching is performed. Can be realized.

Thirdly, by shifting the engine 1 to idle operation at the time of mode switching, it is possible to suppress variations in the engine torque Trqeng when releasing the engine side clutch c1 and realize smooth switching with less shock. It becomes.

(Explanation of modified example)
In the above description, when the torque is replaced, the total torque is reduced by gradually reducing the torques Trqeng and Trqmg1 generated by the engine 1 and the power generation motor 2 toward 0 Nm, respectively. The engine torque Trqeng can be reduced, for example, by reducing the intake air amount of the engine 1 by controlling the stroll valve. The torque replacement is not limited to this, and it is also possible to stop the supply of fuel to the engine 1 and output the torque equivalent to the friction of the engine 1 by the power generation motor 2.

FIG. 10 shows the operation of the drive system S in that case according to a modified example of the drive system S according to the present embodiment at the time of mode switching from the engine direct connection mode to the series hybrid mode.

In the modified example, when the torque replacement phase Pswt is entered after the motor side clutch c2 is engaged, the fuel supply to the engine 1 is stopped by a so-called fuel cut, while the torque Trqmg1 of the power generation motor 2 is before the mode switching. Although it is reduced from the torque of, the friction torque Trqeng (<0) of the engine 1 is maintained by the amount that can be canceled (time 41). Then, it is assumed that the torque replacement is completed by executing the fuel cut (time t41), and the release of the engine side clutch c1 is started. When the torque transmitted from the drive wheels 7 via the engine-side clutch c1 disappears due to the decrease in torque capacity, the rotations of both the engine 1 and the power generation motor 2 stop.

In this way, when the mode is switched from the engine direct connection mode to the series hybrid mode, the total torque generated by the engine 1 and the power generation motor 2 is quickly reduced by stopping the supply of fuel to the engine 1, and the torque is replaced. Can be completed in a short time (torque replacement phase Pswt) (time t41). Here, the friction torque of the engine 1 has a characteristic that is substantially determined according to the rotation speed of the engine 1 and the throttle opening at that time, and the power generation motor 2 accurately outputs the torque equivalent to the friction of the engine 1. Therefore, the total torque can be brought close to 0 Nm, and the shock generated when the engine side clutch c1 is released can be suppressed.

(Explanation of other embodiments)
When replacing the torque, the replacement by shifting the engine 1 to 0 Nm operation (Fig. 8) and the replacement by stopping the fuel supply to the engine 1 (Fig. 10) should be switched according to the situation. It may be. As a situation in this case, it can be exemplified that the driving mode is switched in a hurry, specifically, the driving mode switching is caused by the accelerator operation by the driver.

FIG. 11 shows the contents of processing in the torque replacement phase of the mode switching control according to another embodiment of the present invention.

In the flowchart shown in FIG. 11, in S401, the accelerator opening APO is read.

In S402, the amount of change ΔAPO per unit time of the accelerator opening APO is calculated, and it is determined whether or not this amount of change ΔAPO is larger than the predetermined amount ΔAPO1. If the amount of change ΔAPO is larger than the predetermined amount ΔAPO1, the process proceeds to S403, and if it is smaller than the predetermined amount ΔAPO1, the process proceeds to S404.

In S403, the replacement of torque by stopping the supply of fuel to the engine 1 is selected.

In S404, the torque replacement by shifting the engine 1 to 0 Nm operation is selected.

In S405 to 407, the same processing as that performed in S302 to 304 of the flowchart shown in FIG. 7 is performed.

According to the present embodiment, when the accelerator operation is large, that is, when the change amount ΔAPO of the accelerator opening APO is larger than the predetermined amount ΔAPO1, the total torque is quickly reduced by stopping the supply of fuel to the engine 1. When the accelerator operation is small, that is, when the change amount ΔAPO of the accelerator opening APO is smaller than the predetermined amount ΔAPO1 while the switching is completed in a short time, the engine 1 is shifted to 0 Nm operation. , It is possible to realize smooth switching with suppressed shock.

As described above, according to the present embodiment, it is possible to change the torque or switch the traveling mode by an appropriate method according to the situation.

FIG. 12 shows a flow of mode switching determination according to still another embodiment of the present invention. The controller 101 executes the mode switching determination according to the present embodiment at a predetermined cycle.

In the present embodiment, the mode selection map to be referred to when determining the driving mode for each driving area is switched according to the conditions. Specifically, the engine direct connection permission map shown in FIG. 13A and the drive are selected when there is no drive system S in a state where the power generation of the power generation motor 2 is restricted according to the conditions related to the possibility of power generation. The mode selection map is switched between the engine direct connection prohibition map shown in FIG. 6B, which is selected when the system S is in such a state. In the present embodiment, it is determined whether or not the power generation of the power generation motor 2 is in a restricted state according to the charging state SOC of the battery 4, and in the engine direct connection prohibition map, an area in which the engine direct connection mode is selected is set. Instead, the series hybrid mode is selected over the entire operating area. That is, when the power generation is restricted, the engine direct connection mode is not selected, and therefore the traveling mode is not switched.

Then, in the present embodiment, the switching of the driving mode between the engine direct connection mode and the series hybrid mode is not only due to the change in the operating state (for example, the change indicated by the arrows a1 to a4), but also due to the change in the charging state SOC. It can occur (eg, the change indicated by arrow b1). For example, during the selection of the map shown in FIG. 13 (A), the area B is where the battery 4 is being charged and the charged state SOC is sufficiently high, and the mode selection map is shown in FIG. 13 (B). When switched to the map.

In addition to the above, a case where the power generation motor 2 has excessive heat can be exemplified as a case where the power generation of the power generation motor 2 is restricted.

The engine direct connection permission map shown in FIG. 13A is the same as the mode selection map shown in FIG.

In the flowchart shown in FIG. 12, the steps for performing the same processing as the flowchart shown in FIG. 5 are designated by the same reference numerals as those in FIG.

After reading the operating state of the vehicle in S101, the charging state SOC of the battery 4 is read in S501.

In S502, it is determined whether or not the power generation of the power generation motor 2 is in a restricted state based on the read charging state SOC. Specifically, it is determined whether or not there is a risk of overcharging in further charging of the battery 4, and if there is a risk of overcharging, it is assumed that the power generation of the power generation motor 2 is restricted, S503. If the battery 4 is not in such a highly charged state, it is assumed that the power generation of the power generation motor 2 is not in a restricted state, and the process proceeds to S504.

In the present embodiment, when the engine 1 is operated at the most efficient operating point in the engine direct connection mode, and there is a surplus in the output due to the operation at the maximum efficiency point with respect to the required output of the system S. The surplus output is converted into electric power by the power generation motor 2 and used for charging the battery 4. Therefore, when the power generation of the power generation motor 2 is restricted, the operation in the engine direct connection mode is prohibited and the series hybrid mode is selected by selecting the mode switching map shown in FIG. 13 (B). .. Since there is a risk of overcharging the battery 4, in the series hybrid mode in this case, the engine 1 is not driven, and the traveling motor 3 is driven only by the electric power supplied from the battery 4.

In S503, the engine direct connection prohibition map is selected as the mode switching map.

In S504, the engine direct connection permission map is selected as the mode switching map.

Then, it is determined whether or not the mode is being switched (S102), and if the mode is being switched, the process proceeds to S103 and the mode switching control is executed. On the other hand, if it is not at the time of mode switching, the mode switching control is not executed and the control by the current routine is terminated.

When switching the driving mode due to the progress of charging of the battery 4, in other words, when switching the mode accompanying the switching from the engine direct connection permission map to the engine direct connection prohibition map, this replacement is performed by the driver. Since it is not based on the intention, it is preferable to shift the engine 1 to 0 Nm operation in order to suppress the detection by the driver as much as possible by making the switching smooth.

On the other hand, the mode switching when the power generation of the power generation motor 2 is not restricted, in other words, the torque when the mode is switched due to the change in the operating state (arrows a1 to a4) in the engine direct connection permission map. The replacement can be performed by causing the power generation motor 2 to generate power and canceling the engine torque Trqeng with the regenerative torque Trqmg1 (<0). The operation of the drive system S in this case may be the same as that shown in FIG. 8 as a comparative example.

According to this embodiment, when the power generation of the power generation motor 1 is in a system state in which the power generation is restricted, the total torque of the engine 1 and the power generation motor 2 is reduced without generating power of the power generation motor 2 when switching the traveling mode. By releasing the engine-side clutch c1 by the method of making the motor (referred to as "replacement of torque not by power generation"), it is possible to avoid overcharging of the battery 4 and protect the electrical parts constituting the drive system S. It becomes.

In the above description, not only the engine side clutch (first clutch) c1 that connects the internal combustion engine 1 and the drive wheel 7 but also the motor side clutch (second clutch) c2 that connects the traveling motor 3 and the drive wheel 7 is used. However, the case is not limited to this, and of the engine side clutch c1 and the motor side clutch c2, only the engine side clutch c1 is provided, and the traveling motor 3 and the drive wheel 7 are directly connected without a clutch. It is also possible to make the configuration.

Although the embodiment of the present invention has been described above, the above-described embodiment shows only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above-described embodiment. Not the purpose. Various changes and modifications can be made to the above embodiments within the scope of the matters described in the claims.

S ... Hybrid drive system 1 ... Internal engine 2 ... Power generation motor 3 ... Travel motor 4 ... Battery 5 ... Differential gear 6 ... Drive shaft 7 ... Drive wheel c1 ... Engine side clutch c2 ... Motor side clutch 101 ... Controller

Claims (9)

Equipped with a hybrid drive system that transmits driving force to the drive wheels of the vehicle
The hybrid drive system
With an internal combustion engine
A power generation motor arranged so as to be able to generate power by receiving the power of the internal combustion engine,
A traveling motor that can be driven by the electric power generated by the power generation motor,
With
This is a control method for an electric vehicle having a first clutch for connecting the internal combustion engine and the drive wheels, and being configured to be able to switch between a series hybrid mode in which the traveling motor is used as a drive source and a mode directly connected to the engine. hand,
In the series hybrid mode, the first clutch is released and
In the engine direct connection mode, the first clutch is engaged.
At the time of mode switching from the engine direct connection mode to the series hybrid mode,
The total torque generated by the internal combustion engine and the power generation motor is reduced without generating power from the power generation motor powered by the internal combustion engine.
When the total torque reaches 0 Nm or becomes a predetermined value close to 0 Nm or less, the first clutch is released.
How to control an electric vehicle. At the time of mode switching, the supply of fuel to the internal combustion engine is stopped, and the power generation motor outputs torque equivalent to the friction of the internal combustion engine.
The method for controlling an electric vehicle according to claim 1. At the time of the mode switching, the operation is shifted to the operation in which the torque of the internal combustion engine is set to 0 Nm, and the torque output by the power generation motor is set to 0 Nm.
The method for controlling an electric vehicle according to claim 1. At the time of the mode switching, the internal combustion engine is shifted to idle operation, and the total torque approaches 0.
The method for controlling an electric vehicle according to claim 1. At the time of mode switching due to an increase in accelerator opening,
When the amount of change in the accelerator opening is larger than a predetermined amount, the supply of fuel to the internal combustion engine is stopped to reduce the total torque.
When the amount of change in the accelerator opening is smaller than the predetermined amount, the operation is shifted to the operation in which the torque of the internal combustion engine is set to 0 Nm, and the total torque is reduced.
The method for controlling an electric vehicle according to claim 1. It is determined whether or not the hybrid drive system is in a system state in which the power generation of the power generation motor is restricted.
When it is determined that the system is in the system state at the time of mode switching, the total torque is reduced without generating power from the power generation motor.
The method for controlling an electric vehicle according to any one of claims 1 to 5. When the hybrid drive system is in a system state in which the power generation of the power generation motor is restricted, the total torque is reduced without generating power from the power generation motor.
When the hybrid drive system is not in the system state, the regenerative torque that cancels the torque of the internal combustion engine is output by the power generation motor to reduce the total torque.
The method for controlling an electric vehicle according to any one of claims 1 to 5. The method for controlling an electric vehicle according to claim 6 or 7, wherein the hybrid drive system further includes a battery arranged so as to store electric power generated by the power generation motor.
Whether or not it is in the system state is determined based on the charge state of the battery.
How to control an electric vehicle. With an internal combustion engine
A power generation motor arranged so as to be able to generate power by receiving the power of the internal combustion engine,
A traveling motor that can 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 the drive wheels,
With the controller
With
The controller
In the series hybrid mode in which the traveling motor travels by the power transmitted to the driving wheels, the first clutch is released.
In the engine direct connection mode in which at least one of the internal combustion engine and the power generation motor is used as a drive source and the drive source travels by power transmitted to the drive wheels through the first power transmission path, the first clutch is engaged. ,
At the time of mode switching from the engine direct connection mode to the series hybrid mode,
The total torque generated by the internal combustion engine and the power generation motor is reduced without generating power from the power generation motor powered by the internal combustion engine.
When the total torque reaches 0 Nm or becomes a predetermined value close to 0 Nm or less, the first clutch is released.
Drive system for electric vehicles.

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