JP7279320B2 - hybrid vehicle - Google Patents

Description

The present invention relates to a hybrid vehicle including an engine and a motor configured to transmit rotation to the engine via a belt.

A hybrid vehicle such as a hybrid vehicle is equipped with an engine and a motor used for running and driving, and the power of the motor is transmitted to the engine via a belt in order to assist the rotation of the engine. There is However, when the vehicle is running only by the power of the motor, if the required torque increases due to a demand for acceleration or the like, the load on the motor increases, and typically the load on the belt also increases. If such a heavy load on the belt continues, there is a risk that the belt will slip and that the belt will deteriorate.

Therefore, various techniques for suppressing the slip of the belt (hereinafter referred to as "belt slip suppression technology") have been proposed. One example of belt slip suppression technology is to limit the load torque of a generator to an internal combustion engine such as an engine to a value at which the belt does not slip. Then, in one example of such belt slip suppression technology, when limiting the load torque of the generator, the output shortage of the generator caused by the limit of the load torque is calculated, and further, power generation is performed according to the output shortage. It increases the rpm of the machine. (For example, see Patent Document 1.)

JP-A-2006-27598

However, when one example of the belt slip suppression technology is applied to a belt that transmits the power of the motor of a hybrid vehicle to the engine, and the torque of the motor is simply limited to suppress the slip of the belt, the driving of the engine is stopped. In a motor drive mode in which the vehicle travels by driving the motor in a state, a so-called EV (Electric Vehicle) mode, there is a possibility that the actual drive torque of the hybrid vehicle cannot be obtained in accordance with the driver's request, for example, the driver's request torque. be.

In addition, in a hybrid vehicle that switches between the motor drive mode and the engine drive mode in which the engine is driven, the number of rotations of the motor is reduced according to the amount of output shortage of the motor, as in the belt slip suppression technology described above. If it is increased, it becomes extremely difficult to efficiently set a state in which belt slippage is suppressed and the output shortage of the motor is compensated for, in consideration of the state of the belt, switching between the motor drive mode and the engine drive mode, and the like. Therefore, the feeling of acceleration of the hybrid vehicle may be lost, and the driver may feel uncomfortable with the operation. That is, drivability may deteriorate.

In view of such circumstances, in a hybrid vehicle, it is necessary to efficiently obtain an actual drive torque that meets the driver's request while efficiently suppressing belt slippage, and to efficiently prevent deterioration in drivability. is desired. Concomitantly, in hybrid vehicles, it is desirable to prevent belt deterioration.

In order to solve the above-described problems, a hybrid vehicle according to one aspect is a hybrid vehicle including an engine and a motor configured to assist rotation of the engine via a belt, Control the driving of the engine and the driving of the motor so as to switch between a motor driving mode in which driving is performed using the motor while driving of the engine is stopped and an engine driving mode in which driving is performed using the driving of the engine. and a torque setting unit configured to set a limit torque, which is a threshold value for limiting the torque output from the motor in order to prevent the belt from slipping. , the limit torque is set smaller as the rotational speed of the engine increases, and the drive control unit resumes driving the engine when the required drive torque is larger than the limit torque during the motor drive mode. , the mode is switched to the engine drive mode and the switching to the motor drive mode is prohibited.

In the hybrid vehicle according to one aspect, it is possible to efficiently obtain an actual drive torque that meets the driver's request while efficiently suppressing belt slippage, thereby efficiently preventing deterioration in drivability. Additionally, in a hybrid vehicle, deterioration of the belt can be prevented.

1 is a configuration diagram schematically showing a drive mechanism of a hybrid vehicle according to this embodiment; FIG. 1 is a configuration diagram schematically showing a hybrid ECU, an engine ECU, and a motor ECU of a hybrid vehicle according to the present embodiment; FIG. It is an example of a map used for setting a limit torque and a permission torque in the hybrid vehicle according to the present embodiment. 4 is a flowchart showing an example of drive control of the hybrid vehicle according to the present embodiment;

A hybrid vehicle according to this embodiment will be described. It should be noted that such a hybrid vehicle is preferably a hybrid vehicle. However, the hybrid vehicle may be other than the hybrid vehicle, for example, the hybrid vehicle may be a hybrid motorcycle or the like. Also, in this application, the term "motor" is defined to include an electric motor and a generator-motor, that is, a motor-generator.

[Outline of hybrid vehicle]
First, an outline of a hybrid vehicle will be described. As shown in FIG. 1, the hybrid vehicle has an engine 1 used for driving. The hybrid vehicle also has a motor generator 2 configured as a motor used for driving the vehicle. The hybrid vehicle also has a belt 3 that transmits rotation of the motor generator 2 to rotation of the engine 1 . The motor generator 2 can assist rotation of the engine 1 via the belt 3 . That is, the hybrid system of the hybrid vehicle according to the present embodiment is a so-called belt-driven ISG (Integrated Starter Generator) hybrid system.

Here, in the present embodiment, the case where the motor generator 2 transmits its rotation to the engine 1 will be described, but the motor generator 2 can also generate power by the rotation transmitted from the engine 1 to the motor generator 2 . However, the motor of the hybrid vehicle can be other than the motor generator. For example, the motor of the hybrid vehicle can also be an electric motor.

Such a hybrid vehicle has a hybrid ECU (Electronic Control Unit) 21 which is a hybrid control device configured to be able to control the engine 1 and the motor generator 2 . Note that the hybrid control device can be other than the hybrid ECU.

As shown in FIG. 2 , the hybrid ECU 21 has a drive control section 31 configured to control the driving of the engine 1 and the driving of the motor generator 2 . The drive control unit 31 can switch between a motor drive mode in which the vehicle is driven by the motor generator 2 while the engine 1 is stopped and an engine drive mode in which the vehicle is driven by the engine 1. Configured. In the engine drive mode, the hybrid vehicle can run using only the drive of the engine 1, and can run using the drive of the engine 1 and the drive of the motor generator 2 that assists the rotation of the engine 1. . Further, in the motor drive mode, the hybrid vehicle can run using only the drive of the motor generator 2 . The hybrid ECU 21 also has a torque setting unit 32 configured to set a limit torque E (N·m), which is a threshold value for limiting the torque output from the motor generator 2 in order to prevent the belt 3 from slipping. have

In the hybrid ECU 21, the drive control unit 31 resumes driving the engine 1 when the required drive torque T (Nm) is greater than the limit torque E set by the torque setting unit 32 during the motor drive mode. It is configured to switch to the engine drive mode and to prohibit switching to the motor drive mode. The required driving torque T is the amount of torque required to be output to at least one of the engine 1 and the motor generator 2 according to the driver's acceleration request, deceleration request, desired vehicle speed, and the like. The requested driving torque T is a so-called driver requested torque. The details of the method for calculating the required drive torque T will be described later.

The hybrid vehicle according to this embodiment may be further configured as follows. As shown in FIG. 3, the torque setting unit 32 is configured to set the limit torque E smaller as the calculated value R (%) of the slip ratio of the belt 3 increases. The details of the calculated value R of the slip ratio will be described later.

Furthermore, the torque setting unit 32 is configured to set an allowable torque F (N·m), which is a threshold for allowing torque output from the motor generator 2 . Allowable torque F is smaller than limit torque E. Further, the drive control unit 31 is configured to permit switching to the motor drive mode when the required drive torque T is smaller than the allowable torque F during the motor drive mode. In particular, the drive control unit 31 is configured to permit switching to the motor drive mode when the required drive torque T is smaller than the allowable torque F in a state where switching to the motor drive mode is prohibited. good.

The torque setting unit 32 is configured to set the limit torque E and the allowable torque F smaller as the acquired value ω1 (rpm) of the rotation speed of the engine 1 (hereinafter referred to as “engine rotation speed” as necessary) increases. It is Furthermore, the torque setting unit 32 is configured such that the higher the engine speed, the larger the difference between the limit torque E and the allowable torque F set at the same calculated value R of the slip ratio of the belt 3 .

[Details of hybrid vehicles]
The details of the hybrid vehicle will be explained. That is, the hybrid vehicle may be further configured as follows. As shown in FIG. 1, the engine 1 has an engine body 1a having a power source for driving the engine 1, and rotatable first and second engine rotation shafts 1b and 1c. The first and second engine rotation shafts 1b, 1c are connected to the engine body 1a. The first and second engine rotation shafts 1 b and 1 c are also rotatable by driving the engine 1 and rotatable by rotation transmitted from the motor generator 2 . The rotations of the first and second engine rotation shafts 1b and 1c are synchronized. The engine 1 also has an engine pulley 1d attached to the second engine rotation shaft 1c. The engine pulley 1d is configured so that the belt 3 can be hung thereon.

The motor generator 2 has a motor body 2a having a power source for driving the motor generator 2, and a rotatable motor rotating shaft 2b. The motor rotating shaft 2b is connected to the motor body 2a. The motor rotating shaft 2 b is rotatable by being driven by the motor generator 2 and is rotatable by the rotation transmitted from the engine 1 . The motor generator 2 further has a motor pulley 2c attached to the motor rotating shaft 2b. The motor pulley 2c is configured so that the belt 3 can be hung thereon.

Belt 3 has a tension set to be applied to engine pulley 1d and motor pulley 2c to create friction between belt 3 and engine pulley 1d and motor pulley 2c respectively. When the motor pulley 2c rotates while the belt 3 is hung on the engine pulley 1d and the motor pulley 2c, the belt 3 moves along its circumferential direction, and the engine pulley 1d rotates due to the circumferential movement of the belt 3. do.

Further, the hybrid vehicle has a pair of driving wheels 4 spaced apart from each other in the width direction of the vehicle. The hybrid vehicle has a wheel shaft 5 extending from the traveling drive wheel 4 toward the center in the vehicle width direction along the rotation axis of each traveling drive wheel 4 . Central side end portions of the pair of wheel shafts 5 in the vehicle width direction are connected to a differential gear 6 . The differential gear 6 is configured to provide a rotation difference between the pair of traveling drive wheels 4 .

The hybrid vehicle has a transmission 7 configured to change its speed reduction ratio. The hybrid vehicle also has a clutch 8 connected to the first engine rotation shaft 1 b of the engine 1 and the transmission 7 . The clutch 8 is configured to be switchable between a connected state to enable power transmission from the engine 1 to the transmission 7 and a disconnected state to block this power transmission. The transmission 7 is connected to the differential gear 6 so as to allow power from the engine 1 to be transmitted to the differential gear 6 with the clutch 8 engaged. The differential gear 6 is configured to transmit power from the transmission 7 to the driving wheels 4 through the wheel shafts 5 so as to rotate the driving wheels 4 .

Furthermore, the hybrid vehicle has a starter 9 configured to enable the engine 1 to be started. The hybrid vehicle has two batteries 10,11, namely a first battery 10,11 and a second battery 10,11. The rated voltage of the second battery 11 is preferably higher than the rated voltage of the first battery 10 . In particular, the rated voltage of the first battery 10 may be approximately 12V, ie the first battery 10 may be a 12V (volt) battery. Furthermore, the first battery 10 is preferably a 12V lead battery. In particular, the rated voltage of the second battery 11 may be approximately 48V, ie the second battery 11 may be a 48V battery. Furthermore, the second battery 11 is preferably a 48V lithium ion battery. First battery 10 is electrically connected to starter 9 . Second battery 11 is electrically connected to motor generator 2 .

The hybrid vehicle has a DC-DC converter 12 electrically connected to the first and second batteries 10,11. The DC-DC converter 12 is configured to be able to step up the voltage directed from the first battery 10 to the second battery 11 and to step down the voltage directed to the first battery 10 from the second battery 11. configured to A hybrid vehicle has electrical components 13 such as an audio system, an air conditioner, and various lamps. Such electrical components 13 are electrically connected to the first battery 10 and the DC-DC converter 12 .

Further, the hybrid vehicle has an engine ECU 22 which is an engine control device configured to be able to grasp the state of the engine 1 and control the engine 1 . The engine ECU 22 is electrically connected to the engine 1, the starter 9 and the hybrid ECU 21. The hybrid ECU 21 is configured to be able to receive information such as the state of the engine 1 from the engine ECU 22 , and is configured to be able to transmit instructions regarding the driving state of the engine 1 and the like to the engine ECU 22 .

The hybrid vehicle has a motor ECU 23 which is a motor control device configured to be able to grasp the state of the motor generator 2 and control the motor generator 2 . Motor ECU 23 is electrically connected to motor generator 2 and hybrid ECU 21 . The hybrid ECU 21 is also configured to be able to receive information such as the state of the motor generator 2 from the motor ECU 23 , and is configured to be able to transmit instructions regarding the drive state of the motor generator 2 and the like to the motor ECU 23 .

The hybrid vehicle further includes a battery ECU 24 that is a battery monitoring device configured to be able to grasp the states of the first and second batteries 10 and 11 . In other words, the battery ECU 24 is configured to be able to monitor input/output to the first and second batteries 10 and 11 . The battery ECU 24 is electrically connected to the first and second batteries 10 and 11, the hybrid ECU 21, and the motor ECU 23. The hybrid ECU 21 and the motor ECU 23 adjust the inputs and outputs of the first and second batteries 10 and 11 based on the state information of the first and second batteries 10 and 11 obtained from the battery ECU 24. can be controlled.

Each of the hybrid ECU 21, the engine ECU 22, the motor ECU 23, and the battery ECU includes electronic components such as a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory, input interface, and output interface. and an electric circuit in which such electronic components are arranged. Further, it is preferable that the ROM stores a program for functioning the ECUs 21 to 24 including the ROM. Further, the ROM preferably stores various constants, various maps, and the like used for various calculations.

[Details of hybrid ECU]
Details of the hybrid ECU 21 will be further described. As shown in FIG. 2, the hybrid ECU 21 has an engine rotation speed acquiring section 33 configured to acquire the engine rotation speed. In the hybrid ECU 21, an engine rotation speed acquisition unit 33 provides an acquired value ω1 of the engine rotation speed. In particular, the engine rotation speed acquisition unit 33 is preferably capable of acquiring the engine rotation speed from the engine 1 via the engine ECU 22 .

The hybrid ECU 21 has a motor rotation speed acquisition unit 34 configured to acquire the rotation speed of the motor generator 2 (hereinafter referred to as "motor rotation speed" as necessary). In the hybrid ECU 21, the motor rotation speed acquisition unit 34 provides the acquired value ω2 (rpm) of the motor rotation speed. In particular, the motor rotation speed acquisition unit 34 preferably acquires the motor rotation speed from the motor generator 2 via the motor ECU 23 .

Here, in the hybrid vehicle, the belt 3 may slip on at least one of the engine pulley 1d and the motor pulley 2c. Therefore, the hybrid ECU 21 has a slip ratio calculator 35 configured to calculate the slip ratio of the belt 3 based on the acquired value ω1 of the engine rotation speed and the acquired value ω2 of the motor rotation speed. Note that the rotation speed of the engine 1 corresponds to the rotation speed of the first and second rotating shafts 1b and 1c. Also, the rotational speeds of the first and second rotating shafts 1b and 1c are substantially the same. The rotation speed of the motor generator 2 corresponds to the rotation speed of the second engine rotating shaft 1c.

In the hybrid ECU 21, a calculated value R (%) of the slip ratio is provided by the slip ratio calculator 35. FIG. The calculated value R (%) of the slip ratio can be obtained by the following (Equation 1) based on the obtained value ω1 of the engine rotation speed and the obtained value ω2 of the motor rotation speed.

R=(|ω2−ω1|/ω2)×100 (Formula 1)

In calculating the limit and permission torques E and F in the torque setting unit 32, as shown in FIG. A map determined based on the relationship (hereinafter referred to as "torque setting map") is used. The torque setting map is preferably stored in the ROM of the hybrid ECU 21 . However, the torque setting map can also be stored outside the ROM of the hybrid ECU.

Specifically, in the torque setting map of FIG. 3, the horizontal axis is set to indicate the acquired value ω1 of the engine speed, and the vertical axis is set to indicate the limit and allowable torques E and F, respectively. ing. Further, a plurality of limit torque setting lines M1, M2, M2, M2, M2, M2, M1, M2, M2, M1, M2, M1, M2, M1, M2, M1, M2, M1, M2, M1, M2, M1, M2, M2, M2, M2, M1, M2, M2, M2, M2, M2, M2, etc., which define the relationship between the obtained value ω1 of the engine speed and the limit torque E so as to correspond to a plurality of calculated values R1, R2, R3, . . . of the slip ratio. M3, . . . (indicated by solid lines) are set. A plurality of allowable torque setting lines N1, N2, N3, N3, N2, N3, . . . . (indicated by a dashed line) are set. In such a torque setting map, it is possible to obtain the limit and allowable torques E and F corresponding to the obtained value ω1 of the slip ratio R and the engine rotation speed.

At the same acquired value ω1 of the engine speed, the limit torque E of the plurality of limit torque setting lines M1, M2, M3, . The torque E is set to be small. At the same acquired value ω1 of the engine speed, the limit torque E of the plurality of permission torque setting lines N1, N2, N3, . set to be small.

The limit torque E of each limit torque setting line M1, M2, M3, . The allowable torque F on each of the allowable torque setting lines N1, N2, N3, .

With regard to the limit torque setting lines M1, M2, M3, . . . and the allowable torque setting lines N1, N2, N3, . At the acquired value ω1 of the engine speed, the limit torque E of the limit torque setting lines M1, M2, M3, . is set. Furthermore, regarding the limit torque setting lines M1, M2, M3, . . . and the allowable torque setting lines N1, N2, N3, . The difference between the limit torque E of the limit torque setting lines M1, M2, M3, . . . and the allowable torque F of the allowable torque setting lines N1, N2, N3, . It is set to increase as the acquired value ω1 of the rotation speed increases.

In the torque setting map of FIG. 3, as an example, the first limit torque setting line M1 and the first allowable torque setting line N1 are set according to the case where the calculated value R1 of the first slip ratio is approximately 0%. Then, the second limit torque setting line M2 and the second allowable torque setting line N2 are set according to the case where the calculated value R2 of the second slip ratio is approximately 1%, and the calculated value R3 of the third slip ratio is approximately A third limit torque setting line M3 and a third permission torque setting line N3 are set according to the case of 2%.

Further, the hybrid ECU 21 has an accelerator opening acquisition section 36 configured to enable acquisition of the accelerator opening. In the hybrid ECU 21, an accelerator opening acquisition unit 36 provides an acquired value A (%) of the accelerator opening. In particular, the accelerator opening acquisition unit 36 preferably acquires the accelerator opening from the engine 1 via the engine ECU 22 .

The hybrid ECU 21 has a vehicle speed obtaining section 37 configured to obtain the vehicle speed. In the hybrid ECU 21, a vehicle speed acquisition unit 37 provides an acquired value V (km/h) of the vehicle speed. The vehicle speed acquisition unit 37 may acquire the vehicle speed from a vehicle speed sensor (not shown) or the like of the hybrid vehicle.

The hybrid ECU 21 has a required driving torque calculation section 38 configured to calculate a required driving torque T based on the acquired value A of the accelerator opening and the acquired value V of the vehicle speed. In particular, in the calculation of the required driving torque T, a map that defines the relationship between the required driving torque T, the acquired value A of the accelerator opening, and the acquired value V of the vehicle speed (hereinafter referred to as "required driving torque map ) may be used. The required drive torque map is preferably stored in the ROM of the hybrid ECU 21 . However, the required drive torque map can also be stored in a place other than the ROM of the hybrid ECU.

Further, the required driving torque T is based on the engine required driving torque T1 (N·m) required for the engine 1 and the motor required driving torque T2 (N·m) required for the motor generator 2. determined by For example, when the hybrid vehicle is set to the engine drive mode, the engine required driving torque T1 can be set to be substantially equal to the required driving torque T.

For example, when the hybrid vehicle is set to the motor drive mode, the motor required driving torque T2 can be set to be substantially equal to the required driving torque T. It should be noted that the sum of the engine and motor drive torque requirements T1 and T2 can be set substantially equal to the drive torque requirement T according to the state of the hybrid vehicle. For example, when the hybrid vehicle is in the process of switching between the engine drive mode and the motor drive mode, the total value of the engine and motor required driving torques T1 and T2 is kept substantially equal to the required driving torque T. , the engine and motor required drive torques T1 and T2 may be increased or decreased.

In the hybrid ECU 21, the drive control section 31 preferably has an engine drive execution instruction section 31a configured to instruct the engine 1 and the motor generator 2 to execute the engine drive mode via the engine ECU 22 and the motor ECU 23, respectively. The drive control unit 31 preferably has a motor drive execution instruction unit 31b configured to instruct the engine 1 and the motor generator 2 to execute the motor drive mode via the engine ECU 22 and the motor ECU 23, respectively.

The drive control unit 31 has an engine drive switching determination unit 31c configured to determine whether or not the required drive torque T is greater than the limit torque E when the hybrid vehicle is in the motor drive mode. The drive control unit 31 instructs the engine drive execution instructing unit 31a and the motor to switch from the motor drive mode to the engine drive mode when the engine drive switching determination unit 31c determines that the required drive torque T is larger than the limit torque E. It has an engine drive switching instructing section 31d that instructs the drive execution instructing section 31b. When the engine drive switching determination unit 31c determines that the required drive torque T is greater than the limit torque E, the drive control unit 31 issues an engine drive execution instruction to prohibit switching from the engine drive mode to the motor drive mode. It further includes a motor drive switching inhibition unit 31e configured to instruct the unit 31a and the motor drive execution instructing unit 31b.

The drive control unit 31 has a motor drive switching determination unit 31f configured to determine whether or not the required drive torque T is smaller than the allowable torque F when the hybrid vehicle is in the motor drive mode. In particular, when the hybrid vehicle is in the engine drive mode and switching from the engine drive mode to the motor drive mode is prohibited by the motor drive switching prohibition unit 31e, the motor drive switching determination unit 31f determines that the required drive torque T is It may be configured to determine whether or not it is smaller than the allowable torque F. The drive control unit 31 is configured to permit switching from the engine drive mode to the motor drive mode when the motor drive switching determination unit 31f determines that the required drive torque T is smaller than the allowable torque F. It has a switching permitting section 31g. In particular, the motor drive switching permitting section 31g is configured to cancel the prohibition of switching to the motor drive mode when the required drive torque T is smaller than the permission torque F in a state in which switching to the motor drive mode is prohibited. should be.

When the motor drive switching determination unit 31f determines that the required drive torque T is smaller than the allowable torque F, the drive control unit 31 instructs the engine drive execution instructing unit 31a and the motor drive mode to switch from the engine drive mode to the motor drive mode. It further has a motor drive switching instructing section 31h that instructs the execution instructing section 31b.

Further, the torque setting unit 32 includes a limit torque setting unit 32a configured to set the limit torque E as described above and a permission torque setting unit 32b configured to set the permission torque F as described above. and

[Regarding hybrid vehicle control method]
An example of the hybrid vehicle control method according to the present embodiment will be described below. First, the hybrid vehicle is in motor drive mode (step S1). It is determined whether or not the required drive torque T is greater than the limit torque E (step S2). When the required drive torque T is equal to or less than the limit torque E (NO), the hybrid vehicle continues the motor drive mode (step S1). If the required drive torque T is greater than the limit torque E (YES), the motor drive mode is switched to the engine drive mode (step S3). Further, switching from the engine drive mode to the motor drive mode is prohibited (step S4).

It is determined whether or not the required drive torque T is smaller than the allowable torque F (step S5). If the required drive torque T is equal to or greater than the allowable torque F (NO), the hybrid vehicle continues the engine drive mode (step S3). If the required drive torque T is smaller than the allowable torque F (YES), switching from the engine drive mode to the motor drive mode is permitted (step S6). Further, the engine drive mode is switched to the motor drive mode (step S7). These steps are performed repeatedly.

As described above, in the hybrid vehicle according to the present embodiment, when the required drive torque T is greater than the limit torque E during the motor drive mode, the motor drive mode is switched to the engine drive mode so as to restart the drive of the engine 1 . Therefore, when the belt 3 is about to slip during the motor drive mode, the hybrid vehicle is switched to the engine drive mode. In this engine drive mode, the hybrid vehicle can run while efficiently obtaining the actual drive torque of the vehicle corresponding to the required drive torque T by using the drive of the engine 1 without the belt 3 . In this case, deterioration of drivability can be prevented. Therefore, in the hybrid vehicle, the slip of the belt 3 can be efficiently suppressed while the actual drive torque that meets the driver's request can be efficiently obtained, thereby preventing deterioration of drivability. Further, since switching to the motor drive mode is prohibited after switching to the engine drive mode as described above, even if the required drive torque T is not stable, the engine 1 is frequently driven and stopped. This can be efficiently prevented, the load applied to the belt 3 can be efficiently reduced by such repetition, and the deterioration of drivability can be efficiently prevented.

In the hybrid vehicle according to the present embodiment, the torque setting unit 32 sets the limit torque E to be smaller as the calculated value R of the slip ratio of the belt 3 is larger. Therefore, the slip of the belt 3 can be efficiently suppressed. Furthermore, since the slip ratio of the belt 3 tends to increase as the deterioration of the belt 3 progresses, progress of deterioration of the belt 3 can be suppressed by such a setting.

In the hybrid vehicle according to the present embodiment, since the allowable torque F is smaller than the limit torque E, the engine 1 is frequently driven and stopped even when the required drive torque T is not stable. This can be efficiently prevented, the load applied to the belt 3 can be efficiently reduced by such repetition, and the deterioration of drivability can be efficiently prevented. Further, the drive control unit 31 prohibits switching from the engine drive mode to the motor drive mode when the required drive torque T is smaller than the allowable torque F in a state in which switching from the engine drive mode to the motor drive mode is prohibited. can be allowed. Therefore, in the hybrid vehicle, under the condition that the driving torque according to the driver's request can be efficiently obtained while the slip of the belt 3 is efficiently suppressed, the switching to the motor driving mode is prohibited. , the normal state in which switching to the motor drive mode is permitted can be restored. That is, in the hybrid vehicle, it is possible to efficiently obtain the drive torque that meets the driver's request while efficiently suppressing the slippage of the belt 3 so that the normal function can be exhibited.

In general, when the engine speed of the vehicle is high, the accelerator opening is large, and in such a transition period of accelerator operation, the required drive torque T fluctuates greatly in a short time compared to when the engine speed is low. often do. On the other hand, in the hybrid vehicle according to the present embodiment, the larger the acquired value R1 of the engine rotation speed, the difference between the limit and the allowable torques E and F set at the same calculated value R of the slip ratio of the belt 3. is set so that the limit torque E and the allowable torque F are increased. Therefore, even if the engine rotation speed increases and the required driving torque T is not stable, it is possible to efficiently prevent the engine 1 from being repeatedly driven and stopped. It is possible to efficiently reduce the load and effectively prevent deterioration of drivability.

Although the embodiments of the present invention have been described so far, the present invention is not limited to the above-described embodiments, and the present invention can be modified and changed based on its technical ideas.

DESCRIPTION OF SYMBOLS 1... Engine, 2... Motor generator (motor), 3... Belt, 31... Drive control part, 32... Torque setting part E... Limit torque, F... Permission torque, T... Request drive torque, R, R1, R2, R3 ... Calculated value of slip ratio, ω1 ... Acquired value of engine rotation speed

Claims (5)

engine and
A hybrid vehicle comprising a motor configured to assist rotation of the engine via a belt,
The driving of the engine and the driving of the motor are performed in order to switch between a motor drive mode in which the vehicle travels using the drive of the motor while the drive of the engine is stopped and an engine drive mode in which the vehicle travels using the drive of the engine. a drive controller configured to be controllable;
a torque setting unit configured to set a limit torque, which is a threshold value for limiting the torque output from the motor in order to prevent the belt from slipping,
The limit torque is set smaller as the rotational speed of the engine increases ,
The drive control unit switches to the engine drive mode so as to resume driving of the engine and prohibits switching to the motor drive mode when the required drive torque is greater than the limit torque during the motor drive mode. A hybrid vehicle configured to. The drive control unit prohibits switching to the motor drive mode when the required drive torque is greater than the limit torque during the motor drive mode, and thereafter, even if the required drive torque becomes equal to or less than the limit torque. 2. The hybrid vehicle of claim 1, configured to maintain prohibition of switching to the motor drive mode. The hybrid vehicle according to claim 1 or 2, wherein the torque setting unit is configured to set the limit torque smaller as the slip ratio of the belt increases. The torque setting unit is further configured to set an allowable torque, which is a threshold for allowing torque output from the motor,
the allowable torque is smaller than the limit torque,
4. The drive control unit according to any one of claims 1 to 3, wherein the drive control unit is configured to permit switching to the motor drive mode when the required drive torque is smaller than the allowable torque during the engine drive mode. or the hybrid vehicle according to item 1. The torque setting unit is configured to set the limit torque and the allowable torque smaller as the rotation speed of the engine increases, and at the same slip ratio of the belt as the rotation speed of the engine increases. 5. The hybrid vehicle according to claim 4, wherein the set limit torque and the set allowable torque have a large difference.

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