JP7298179B2 - Electric vehicle control method and electric vehicle drive system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a control method and drive system for 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 drive system is known, which is configured to drive a generator with the power of an internal combustion engine, and to operate an electric motor for traveling (hereinafter referred to as a "travel motor") with the electric power generated by the generator. ing. Patent Document 1 discloses 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 travel motor. is disclosed.

Patent Document 1 further discloses that, as a control when switching from an engine direct connection mode to a series hybrid mode using a drive motor as a drive source, while maintaining the output of the engine before switching, some of the output of the engine is transferred to the driving wheels. The ratio of electrical transmission consumed for driving the generator to that consumed for mechanical transmission was increased until 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 disengage the clutch.

WO2011/074483 (Figure 1, paragraphs 0037 and 0038)

However, according to the technique described in Patent Literature 1, maintaining the output of the engine itself during torque replacement may pose a problem. For example, after shifting to the series hybrid mode, even though you want to implement so-called EV driving, in which only the driving motor is driven without driving the engine, the engine is still running when the torque replacement is completed. Since the output is maintained, the transition to EV driving is not sufficiently smooth.

In addition, under conditions where power generation by the generator is restricted, it is not possible to increase the ratio of electrical transmission in the engine output, and switching from engine direct connection mode to series hybrid mode becomes impossible. There is A condition in which power generation by the generator is limited is that the generator produces power that is in excess of the system's required output, but the battery is already in a high state of charge, and the excess power is used to charge the battery. It is possible to exemplify the case where it is not possible to allocate Power generation by the generator is limited to avoid overcharging the battery.

In consideration 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 execution of switching between the series hybrid mode and the engine direct connection mode.

According to one aspect of the present invention, a hybrid drive system that transmits driving force to drive wheels of a vehicle is provided, the hybrid drive system including an internal combustion engine, a generator motor arranged to receive power from the internal combustion engine and generate power, a series hybrid mode having a traveling motor arranged so as to be driven by electric power generated by the generator motor, having a first clutch that connects the internal combustion engine and the drive wheels, and using the traveling motor as a drive source; A control method for an electric vehicle configured to switch between an engine direct connection mode is 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 engine direct connection mode to the series hybrid mode, the generator motor powered by the internal combustion engine does not generate power, and the total torque generated by the internal combustion engine and the generator motor is reduced. When it reaches 0 Nm or becomes below a predetermined value close to 0 Nm, the first clutch is released.

In another form, 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 transferred between the internal combustion engine and the traction motor without generating the power of the generator motor. can be achieved without generating regenerative torque. Therefore, the range of options for the method of replacing the torque is expanded, and it is possible to realize appropriate replacement according to the situation, and it is possible to switch from the engine direct connection mode to the series hybrid mode regardless of the conditions related to whether or not power generation is possible. Since the switching can be performed, it is possible to satisfactorily switch the driving mode.

FIG. 1 is a schematic diagram showing the overall configuration of an electric vehicle drive system according to one embodiment of the present invention. FIG. 2 is an explanatory diagram showing the operation in the series hybrid mode of the drive system according to the embodiment. FIG. 3 is an explanatory diagram showing the operation in the engine direct connection mode of the drive system according to the embodiment. FIG. 4 is an explanatory diagram showing driving modes corresponding to operating regions of the drive system according to the embodiment. FIG. 5 is a flow chart showing the flow of mode switching determination according to the above embodiment. FIG. 6 is a flow chart showing the overall flow of mode switching control according to the embodiment. FIG. 7 is a flowchart showing the content of processing (A) in the torque replacement phase of mode switching control according to the embodiment. FIG. 8 is an explanatory diagram showing the operation of the drive system according to one embodiment of the present invention at the time of mode switching from the engine direct connection mode to the series hybrid mode. FIG. 9 is an explanatory diagram showing the operation according to the comparative example at the time of mode switching from the engine direct connection mode to the series hybrid mode. FIG. 10 is an explanatory diagram showing the operation of the 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 flow chart showing the contents of processing in the torque replacement phase of mode switching control according to another embodiment of the present invention. FIG. 12 is a flow chart showing the flow of mode switching determination according to still another embodiment of the present invention. FIG. 13 is an explanatory diagram showing switching of driving modes (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 S for an electric vehicle (hereinafter referred to as "drive system", sometimes simply referred to as "system") S according to one embodiment of the present invention.

A 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 (hereinafter simply referred to as "engine") 1, an electric motor for power generation (hereinafter referred to as "generating motor") 2, and an electric motor for traveling (hereinafter referred to as "traveling motor") 3. , provided. The terms “for power generation” and “for running” here refer only to their main roles in the drive system S, and the generator motor 2 is responsible for part of driving force formation, and the drive motor 3 is used for control. It goes without saying that a part of power regeneration may be borne.

The engine 1 has its output shaft or crankshaft 11 connected to the rotating shaft 21 of the generator motor 2 via a gear train Ga consisting of a plurality of gears. Torque of the engine 1 is transmitted to the generator motor 2 at a predetermined gear ratio through the gear train Ga, and the generator motor 2 is operated. In this embodiment, the connection between the engine 1 and the generator motor 2 via the gear train Ga is permanent and cannot be cut off.

The generator motor 2 is electrically connected to the travel motor 3 and also connected to the battery 4 , and supplies electric power generated by being supplied with power from the engine 1 to the travel motor 3 or the battery 4 . do. The supply of electric power from the generator motor 2 to the travel motor 3 and the supply of electric power from the generator motor 2 to the battery 4 can be executed according to the operating state of the vehicle, the state of charge of the battery 4, and the like. FIG. 1 schematically shows electrical connections between the generator motor 2, the traction motor 3, and the battery 4 by two-dot chain lines.

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 consisting of a plurality of gears. Torque of the traveling motor 3 is transmitted to the differential 5 at a predetermined gear ratio through the gear train Gb, and further distributed to the left and right drive shafts 6, 6 via the differential 5 to rotate the drive wheels 7 and drive the vehicle. promote. In this 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, and in addition to propelling the vehicle, it receives power from the drive wheels 7 via a gear train Gb. , it is also possible to generate electricity. Electric power generated by the traction motor 3 can be supplied to the battery 4 and used to charge the battery 4 .

Furthermore, in the present embodiment, the engine 1 has the output shaft 11 connected to the ring gear of the differential 5 via a gear train Gc consisting 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 is distributed to the left and right drive shafts 6, 6 via the differential 5, thereby rotating the drive wheels 7 and propelling the vehicle. be done.

In this embodiment, clutches c1 and c2 are interposed in the gear train Gc and the gear train Gb, respectively. The connection via the gear train Gb can be cut off by clutches c1 and c2, respectively. Both of the clutches c1 and c2 may be mesh clutches, and a dog clutch can be exemplified as one applicable to the clutches c1 and c2. In this embodiment, dog clutches are employed as the clutches c1 and c2.

In a clutch (hereinafter sometimes referred to as an "engine-side clutch") c1 provided in the gear train Gc, one of the clutch elements or meshing elements rotates on the output shaft 11 of the engine 1 so as not to rotate relative to the output shaft 11. It is configured to be slidable, and engages with the other clutch element or meshing element provided on the gear arranged coaxially with the output shaft 11 to enable transmission of power through the gear train Gc.

Similarly, in the clutch c2 provided in the gear train Gb (hereinafter sometimes referred to as the "motor-side clutch"), one of the clutch elements or meshing elements is relatively non-rotatable with respect to the rotating shaft 31 of the traveling motor 3. It is configured to be slidable on the shaft 31, and engages with the other clutch element or meshing element provided on the gear arranged coaxially with the rotation shaft 31, thereby enabling transmission of power 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 a "second clutch" according to this embodiment.

The operations of the engine 1, the generator motor 2, the travel motor 3 and the states of the clutches c1, c2 are electronically controlled by the controller 101. FIG. Although not limited to this, the controller 101 is composed of a microcomputer having a central processing unit (CPU), various storage units such as ROM and RAM, an input/output interface, etc., 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 operation amount 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 rotational speed Neng of the engine 1 are A signal indicating the rotation speed Nmg1 of the generator motor 2 and a signal indicating the rotation speed Nmg2 of the travel motor 3 are input to the controller 101 . For detection of various parameters, an accelerator opening sensor 201 for detecting the accelerator opening APO, a vehicle speed sensor 202 for detecting the vehicle speed VSP, and the rotation speed Neng of the engine 1 for detecting the rotation speed per unit time (hereinafter referred to as "engine rotation speed ), a generator motor rotation speed sensor 204 that detects the rotation speed Nmg1 of the generator motor 2 as the rotation speed of the generator motor, and a rotation speed Nmg2 of the travel motor 3 that is detected as the rotation speed of the travel motor. A motor speed sensor 205 is provided.

The controller 101 executes predetermined calculations based on various signals that have been input, controls the operations of the engine 1, the generator motor 2, and the travel motor 3, and also controls the states of the clutches c1 and c2.

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

2 and 3 show the operation of the drive system S according to the running mode, with FIG. 2 showing the operation in the series hybrid mode and FIG. 3 showing the operation in the engine direct connection mode. Figures 2 and 3 show the path along which power is transmitted by thick dashed lines with arrows, the arrows indicating the direction along which power is transmitted.

In the series hybrid mode, as shown in FIG. 2, the clutch c1 is released while the clutch c2 is engaged, so that the torque of the engine 1 can be transmitted to the generator motor 2 through the gear train Ga, and the torque of the travel 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 disengaged 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 generator motor 2 functions not only as a generator but also as an electric motor, it is possible to generate torque from the generator motor 2 and transmit it to the driving wheels 7 through the gear trains Ga and Gc.

In this embodiment, in the engine direct connection mode, power transmission between the travel motor 3 and the drive wheels 7 is cut off by releasing the clutch c2 on the power transmission path connecting the travel motor 3 and the drive wheels 7. , to prevent the traveling motor 3 from being rotated together with the rotation of the driving wheel 7. - 特許庁However, the clutch c2 may be engaged as well as disengaged. As a result, in addition to the torque of the engine 1, the torque of the travel motor 3 can also be transmitted to the drive wheels 7. In the engine direct connection mode, the clutch c2 may be engaged or disengaged depending on the situation.

(Control related to mode switching)
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 driving modes according to the driving range of the vehicle.

In this embodiment, a mode selection map that defines the driving mode for each operating area is created in advance and 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 other ranges. In this embodiment, the engine direct connection mode is selected in the high speed region B where the load is relatively low, and the series hybrid mode is selected in the other region A. The controller 101 refers to the mode selection map based on the vehicle speed VSP and the accelerator opening APO to determine the driving regions A and B to which the vehicle driving state belongs, and switches the driving mode according to the determination result.

Control related to switching of driving modes (hereinafter referred to as "mode switching control") will be described below. After describing the overall flow with reference to a flow chart, a more specific description will be given with reference to a time chart.

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

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

In S102, it is determined whether or not the mode is switched. Specifically, whether the operating state of the vehicle, which is determined by the accelerator opening APO and the vehicle speed VSP, has shifted from the series hybrid mode region A to the engine direct coupling mode region B among the driving regions A and B shown in FIG. Or, on the contrary, it is determined whether the region B has shifted to the region A. If there is a transition in the operating state between the operating regions A and B and the mode switching is in progress, the process proceeds to S103, and if the mode switching is not in the mode switching, the control by the current routine ends.

In S103, mode switching control is executed.

Moving on to the flowchart shown in FIG. Determine whether or not there is If it is the switching to the series hybrid mode, the process proceeds to S202, and if it is not the switching to the series hybrid mode but the switching from the series hybrid mode to the engine direct connection mode, the control by this routine ends. In FIG. 4, the arrows a1 to a4 show how the operating state shifts from region B in the engine direct connection mode to region A in the series hybrid mode.

In S202, control (hereinafter referred to as "rotation synchronization control") is started to match the rotational speeds of the drive element and the driven element of the engagement-side clutch. Here, the engagement-side clutch is a clutch that is engaged after mode switching, and in switching from the engine direct connection mode to the series hybrid mode, the clutch provided in the gear train Gb (that is, the motor side clutch) c2 corresponds. . As rotation synchronization control in this case, torque is generated by the travel motor 3 to increase the travel motor rotation speed Nmg2.

In S203, it is determined whether or not rotation synchronization has been completed. This determination is made, for example, by determining whether or not the difference in rotational speed between the driving element and the driven element of the clutch c2 has decreased to a predetermined value. . If the rotation synchronization is completed, the process proceeds to S204, and if not completed, the determination of S203 is repeated.

In S204, a command to engage the motor-side clutch c2, which is the clutch on the engagement side, is output. If the clutches c1, c2 convert the motion of an actuator (for example, a servo-type electric motor) into movement of a driving element or a driven element via a link mechanism consisting of cams, levers, etc. On the other hand, it outputs a command to operate in the direction to engage the clutch.

In S205, it is determined whether or not the engagement of the clutch c2 has been completed. This determination can be made, for example, by determining whether or not the actuators (specifically, the movable portions thereof) of the clutches c1 and c2 have reached the target position for engagement. If the engagement of the clutch c2 is completed, the processing of the torque replacement phase is executed, so the process proceeds to S301 of 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 driving mode has been completed, and then the control by the current routine ends.

Moving on to the flow chart shown in FIG. 7, in S301, the control for switching the torque between the drive source before mode switching and the drive source after mode switching is started. In the present embodiment, when switching from the engine direct connection mode to the series hybrid mode, the generator motor 2 whose power source is the engine 1 does not generate power, and the total torque generated by the engine 1 and the generator motor 2 is reduced toward 0 Nm. Let In other words, "no power generation by the generator motor 2" means that the generator motor 2 does not generate regenerative torque. Including cases where neither is performed. When the generator motor 2 is caused to perform power running, the battery 2 is discharged. 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 the torque of the generator motor 2 is maintained at 0 Nm, and the traveling motor 3 is reduced accordingly. increase the torque of Furthermore, if torque is generated not only by the engine 1 but also by the generator motor 2 before the mode switching, the total torque generated by the engine 1 and the generator motor 2 is reduced, and the torque of the traveling motor 3 is reduced accordingly. to increase To reduce the total torque, it is possible to simultaneously reduce the torque of the engine 1 and the torque of the generator motor 2 towards 0 Nm.

In S302, it is determined whether or not the replacement of the torque has been completed. For example, it is determined whether or not the total torque generated by the engine 1 and the generator motor 2 has reached 0 Nm, and if it has reached 0 Nm, it is determined that the torque replacement has been completed. If the torque replacement is completed, the process proceeds to S303, and if not completed, the determination of S302 is repeated. Determination of whether or not the torque replacement is completed is not limited to this, but by determining whether or not the total torque has become a predetermined value close to 0 Nm (but greater than 0 Nm) or less. is also possible. When the total torque becomes equal to or less than this predetermined value, it is determined that the torque replacement has been completed.

In S303, a command to release the clutch on the release side is output. For example, a command is output to the actuators of the clutches c1 and c2 to move the clutches in the direction of disengagement. Here, the release-side clutch refers to a clutch that is released after mode switching, and in 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 clutch c1 has been released. This determination can be made, for example, by determining whether or not the actuators of the clutches c1 and c2 (more specifically, their movable portions) have reached the target positions for disengagement. If the release of the clutch c1 is completed, the flow returns to the flowchart shown in FIG. 6, and if not completed, the determination of S304 is repeated.

In this embodiment, when the torque replacement is completed and the torque applied to the input shaft of the engine-side clutch c1 (that is, the torque on the shaft) reaches 0 Nm or a predetermined value close to 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 so that the shaft torque reaches 0 Nm or a predetermined value. It is also possible to configure so that the clutch c1 is disengaged at the point in time. When a dog clutch is employed as the clutch c1, such a mechanism is implemented by, for example, interposing means (e.g., a spring) between the clutch elements of the dog clutch to urge them in a direction to separate them from each other. It is possible.

Now let's move on to explanation using a 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 this embodiment. In FIG. 8 (the same applies to FIGS. 9 and 10 to be described later), the rotational speed N and torque Trq of the engine 1 are indicated by solid lines, those of the generator motor 2 are indicated by two-dot chain lines, and those of the travel motor 3 are indicated by solid lines. are indicated by dotted lines.

In the time chart shown in FIG. 8, after it is determined that it is time to switch 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 Psyn), and the traveling motor 3 to generate a torque Trqmg2 to increase the travel motor rotation speed Nmg2 and bring it closer to the output rotation speed Nout corresponding to the rotation speed of the drive shaft 6. When the difference ΔN (=Nout−Nmg2) between the output rotation speed Nout and the traveling motor rotation speed Nmg2 has decreased to a predetermined value (time t21), it is considered that the rotation synchronization is completed, and the clutch engagement phase Pegm is started. The side clutch c2 is engaged. In the clutch engagement phase Pegm, the torque Trqmg2 of the traction motor 3 is reduced to zero. When the engagement of the motor-side clutch c2 is completed (time t31), the transition is made to the torque replacement phase Pswt, in which the torque transmitted to the driving wheels 7 through the engine-side clutch c1 is reduced, and correspondingly through the motor-side clutch c2. The torque transmitted to the drive wheels 7 is increased. Specifically, while reducing the total torque (=Trqeng+Trqmg1) generated by the engine 1 and the generator motor 2 at a predetermined decrease rate ΔTdec, the torque Trqmg2 of the traveling motor 3 is increased at a predetermined increase rate ΔTinc according to the decrease rate ΔTdec. Increase. In the present embodiment, both the torque Trqeng of the engine 1 and the torque Trqmg1 of the generator motor 2 are simultaneously reduced toward zero. After the total torque reaches 0, the engine 1 is shifted to an operation where the torque Trqeng is 0 Nm (hereinafter referred to as "0 Nm operation"), and the torque Trqmg1 output by the generator motor 2 is set to 0 Nm. In this embodiment, the rate of decrease ΔTdec of the total torque and the rate of increase ΔTinc of the motor torque Trqmg2 are set equal to each other. When the total torque reaches 0, it is determined that the torque replacement has been 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. Control ends (time t51).

In this embodiment, after the total torque reaches 0 Nm, the engine 1 is shifted to 0 Nm operation, the torque Trqmg1 output by the generator motor 2 is set to 0 Nm, and after the engine side clutch c1 is released, the engine 1 and the generator motor 2 (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 releasing the engine side clutch c1 The engine 1 and the generator motor 2 may each maintain a rotation speed corresponding to idling.

FIG. 9 shows the operation of the comparative example when switching from the engine direct connection mode to the series hybrid mode. In the comparative example, after the motor-side clutch c2 is engaged and the transition is made to the torque replacement phase Pswt, the torque Trqeng of the engine 1 is maintained at the torque before the mode switching, while the regenerative torque Trqmg1 (<0) is generated by the generator motor 2. brings the total torque close to zero. When the absolute value of the regenerative torque (=|Trqmg1|) becomes equal to the engine torque Trqeng, it is assumed that the torque replacement is completed (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 generator motor 2 also decreases (time t51).

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

First, when the mode is switched from the engine direct connection mode to the series hybrid mode, the torque is transferred between the engine 1 and the traveling motor 3 without generating the power of the generator motor 2 whose power source is the engine 1. , in other words, it is possible to achieve this without causing the generator motor 2 to generate regenerative torque. Therefore, it not only expands the range of options for how to simply replace the torque, but also makes it possible to implement an appropriate replacement according to the situation. , the output of the engine 1 can be lost by the time the torque replacement is completed (time t51 shown in FIG. 8), so that the transition to EV running can be achieved smoothly.

Furthermore, it is possible to switch from the engine direct connection mode to the series hybrid mode regardless of conditions related to whether or not power generation is possible. In the case of the method (FIG. 9) of causing the generator motor 2 to generate electric power and generate regenerative torque, the electric power thus generated is used to charge the battery 4, but the battery 4 is already in a highly charged state, This is because if the electric power cannot be used to charge the battery 4, the battery 4 may be overcharged if it is forced to generate power. According to this embodiment, even in such a situation, it is possible to switch from the engine direct connection mode to the series hybrid mode.

Second, at the time of mode switching, the engine 1 is shifted to 0 Nm operation, and the torque output by the generator motor is set to 0 Nm accordingly, thereby suppressing the shock that occurs when the engine-side clutch c1 is released, resulting in smooth switching. can be realized.

Third, by shifting the engine 1 to idle operation at the time of mode switching, variations in the engine torque Trqeng when disengaging the engine-side clutch c1 can be suppressed, and smooth switching with little shock can be realized. becomes.

(Explanation of modification)
In the above description, when the torque is replaced, the total torque is decreased by gradually decreasing the torques Trqeng and Trqmg1 generated by the engine 1 and the generator motor 2 toward 0 Nm. The engine torque Trqeng can be reduced by, for example, controlling the throttle valve to reduce the intake air amount of the engine 1 . Torque replacement is not limited to this, and can also be achieved by stopping the supply of fuel to the engine 1 and outputting a torque equivalent to the friction of the engine 1 from the generator motor 2 .

FIG. 10 shows, as an operation of the drive system S in that case, an operation according to a modification of the drive system S according to this embodiment at the time of mode switching from the engine direct connection mode to the series hybrid mode.

In the modified example, after the motor-side clutch c2 is engaged and the transition is made to the torque replacement phase Pswt, the supply of fuel to the engine 1 is stopped by so-called fuel cut, while the torque Trqmg1 of the generator motor 2 is reduced to Although the torque is reduced from , the friction torque Trqeng (<0) of the engine 1 is maintained by an amount that can be canceled (time 41). After the fuel cut is executed, the torque replacement is completed (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, both the engine 1 and the generator motor 2 stop rotating.

In this way, by stopping the supply of fuel to the engine 1 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 generator motor 2 is quickly reduced, and the torque is replaced. can be completed within 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 torque equivalent to the friction of the engine 1 is output accurately by the generator motor 2. is possible, the total torque can be brought close to 0 Nm, and the shock that occurs when the engine side clutch c1 is released can be suppressed.

(Description of other embodiments)
When the torque is replaced, the replacement by shifting the engine 1 to 0 Nm operation (Fig. 8) and the replacement by stopping the supply of fuel to the engine 1 (Fig. 10) are switched according to the situation. can be As a situation in this case, it is possible to exemplify a situation in which the driving mode is urgently switched, 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 mode switching control according to another embodiment of the present invention.

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

In S402, the change amount ΔAPO of the accelerator opening APO per unit time is calculated, and it is determined whether or not this change amount ΔAPO is larger than a 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, torque replacement by stopping the supply of fuel to the engine 1 is selected.

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

In S405-407, the same processing as in S302-304 in 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 fuel supply to the engine 1 is stopped to quickly reduce the total torque. and the switching is completed within a short time. , it is possible to achieve smooth switching with reduced shock.

As described above, according to the present embodiment, it is possible to achieve replacement of torque or switching of running modes by an appropriate method according to the situation.

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

In this embodiment, the mode selection map referred to when determining the driving mode for each operating region is switched according to conditions. Specifically, the engine direct connection permission map shown in FIG. The mode selection map is switched between the engine direct connection prohibition map shown in FIG. In this embodiment, whether or not the power generation of the generator motor 2 is restricted is determined according to the state of charge SOC of the battery 4, and the engine direct connection prohibition map sets a region in which the engine direct connection mode is selected. series hybrid mode is selected over the entire driving range. In other words, when power generation is restricted, the engine direct connection mode is not selected, and therefore the running mode is not switched.

In this embodiment, the driving mode is switched between the engine direct connection mode and the series hybrid mode not only by changes in the operating state (for example, changes indicated by arrows a1 to a4) but also by changes in the state of charge SOC. can occur (for example, the change indicated by arrow b1). For example, during the selection of the map shown in FIG. 13(A), the region B was in the state of charge of the battery 4, the state of charge SOC became sufficiently high, and the mode selection map was changed to that shown in FIG. 13(B). This is the case when switching to the map.

In addition to the above, the case where the generator motor 2 is in a state where the power generation of the generator motor 2 is limited can be exemplified by the case where the generator motor 2 has excessive heat.

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

In the flow chart shown in FIG. 12, steps that perform the same processing as in the flow chart shown in FIG. 5 are denoted by the same reference numerals as in FIG.

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

In S502, based on the read state of charge SOC, it is determined whether or not the power generation of the generator motor 2 is restricted. 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 determined that the power generation of the generator motor 2 is limited, and S503 If the battery 4 is not in such a high state of charge, it is determined that the power generation of the generator motor 2 is not limited, and the process proceeds to S504.

In this embodiment, when the engine direct connection mode is used, the engine 1 is operated at the most efficient operating point, and if there is a surplus in the output from operating at this maximum efficiency point with respect to the required output of the system S, , the surplus output is converted into electric power by the generator motor 2 and used to charge the battery 4 . Therefore, when the power generation of the generator motor 2 is restricted, by selecting the mode switching map shown in FIG. 13B, the operation in the engine direct connection mode is prohibited and the series hybrid mode is selected. . Since the battery 4 may be overcharged, in the series hybrid mode in this case, the engine 1 is not driven, and the traction motor 3 is driven only by 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 it is time for mode switching (S102), and if it is time for mode switching, the process advances to S103 to execute mode switching control. On the other hand, if there is no mode switching time, the control by the current routine is terminated without executing the mode switching control.

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

On the other hand, when the power generation of the generator motor 2 is not restricted, in other words, 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 torque is reduced. The replacement can be performed by causing the generator motor 2 to generate power and offsetting 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 previously shown in FIG. 8 as a comparative example.

According to this embodiment, when the system is in a state where the power generation of the generator motor 1 is restricted, the total torque of the engine 1 and the generator motor 2 is reduced without generating the generator motor 2 when switching the driving mode. By disengaging the engine-side clutch c1 by a method (referred to as "replacement of torque not based on power generation"), it is possible to avoid overcharging of the battery 4 and protect the electrical components that make up the drive system S. becomes.

In the above description, not only the engine-side clutch (first clutch) c1 connecting the internal combustion engine 1 and the driving wheels 7 but also the motor-side clutch (second clutch) c2 connecting the traveling motor 3 and the driving wheels 7 are described. However, the present invention is not limited to this, and only the engine-side clutch c1 out of the engine-side clutch c1 and the motor-side clutch c2 is provided, and the traveling motor 3 and the driving wheels 7 are directly connected without intervening the clutch. It is also possible to have a configuration in which

Although the embodiments of the present invention have been described above, the above embodiments merely show a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configurations of the above embodiments. not on purpose. Various changes and modifications can be made to the above-described embodiment within the scope of matters described in the claims.

S... Hybrid drive system 1... Internal combustion 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 power to the vehicle's drive wheels,
The hybrid drive system is
an internal combustion engine;
a generator motor arranged to generate power by receiving power from the internal combustion engine;
a travel motor arranged to be driven by electric power generated by the generator motor;
with
A control method for an electric vehicle that has a first clutch that connects the internal combustion engine and the drive wheels, and is configured to be switchable between a series hybrid mode in which the drive motor is used as a drive source, and an engine direct connection mode. hand,
In the series hybrid mode, releasing the first clutch,
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,
reducing the total torque generated by the internal combustion engine and the generator motor without generating power by the generator motor powered by the internal combustion engine;
releasing the first clutch when the total torque reaches 0 Nm or becomes equal to or less than a predetermined value close to 0 Nm;
A control method for an electric vehicle. When the mode is switched, the supply of fuel to the internal combustion engine is stopped, and torque equivalent to the friction of the internal combustion engine is output by the generator motor.
The method for controlling an electric vehicle according to claim 1. When the mode is switched, the torque of the internal combustion engine is shifted to 0 Nm, and the torque output by the generator motor is set to 0 Nm.
The method for controlling an electric vehicle according to claim 1. At the time of the mode switching, after releasing the first clutch, the rotation speed of the internal combustion engine is controlled to the idle rotation speed.
The method for controlling an electric vehicle according to claim 1. At the time of mode switching due to an increase in accelerator opening,
stopping the supply of fuel to the internal combustion engine to reduce the total torque when the amount of change in the accelerator opening is greater than a predetermined amount;
If the amount of change in the accelerator opening is smaller than the predetermined amount, the torque of the internal combustion engine is shifted to 0 Nm to reduce the total torque.
The method for controlling an electric vehicle according to claim 1. determining whether the hybrid drive system is in a system state in which the power generation of the generator motor is restricted;
At the time of the mode switching, if it is determined that the system state is present, the generator motor does not generate power and the total torque is reduced , and if it is determined that the system state is not present, the torque of the internal combustion engine is offset. outputting the regenerative torque generated by the generator motor to reduce the total torque;
The control method for an electric vehicle according to any one of claims 1 to 5. when the hybrid drive system is in a system state in which power generation by the generator motor is restricted, reducing the total torque without generating power by the generator motor;
When the hybrid drive system is not in the system state, the generator motor outputs a regenerative torque that offsets the torque of the internal combustion engine to reduce the total torque.
The control method for an electric vehicle according to any one of claims 1 to 5. 8. The electric vehicle control method according to claim 6, wherein said hybrid drive system further comprises a battery arranged to store electric power generated by said generator motor,
Determining whether the system is in the state based on the state of charge of the battery;
A control method for an electric vehicle. an internal combustion engine;
a generator motor arranged to generate power by receiving power from the internal combustion engine;
a traveling motor arranged to be driven by electric power generated by the generator motor;
a first clutch interposed in a first power transmission path connecting the internal combustion engine and drive wheels;
a controller;
with
The controller is
In a series hybrid mode in which the traveling motor travels by power transmitted to the drive wheels, the first clutch is released,
In an engine direct connection mode in which at least one of the internal combustion engine and the generator motor is used as a drive source and the vehicle travels by power transmitted from the drive source to the drive wheels through the first power transmission path, the first clutch is engaged. ,
At the time of mode switching for switching from the engine direct connection mode to the series hybrid mode,
reducing the total torque generated by the internal combustion engine and the generator motor without generating power by the generator motor powered by the internal combustion engine;
releasing the first clutch when the total torque reaches 0 Nm or becomes equal to or less than a predetermined value close to 0 Nm;
Electric vehicle drive system.

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