JP2020111276A - Control device for vehicle - Google Patents

Abstract

To suppress an increase in heat generation amount of a connecting/disconnecting clutch at start of an engine in a control device for a vehicle that starts the engine from a traveling mode using only an electric motor as a driving source.SOLUTION: A control device 10 is applied to a hybrid vehicle. The control device 10 includes a vehicle control section 11 performing traveling mode change processing for starting an engine 91 while controlling a connecting/disconnecting clutch 81 toward engagement, when a vehicle is traveled by using an electric motor 82 with the connecting/disconnecting clutch 81 disengaged. The control device 10 includes a differential rotation determination section that allows starting of the engine 91 in the traveling mode change processing when rotational frequency of the electric motor 82 is larger than an engine start determination value. The control device 10 includes a determination value setting section 13 that sets the engine start determination value to a smaller value when a lock-up clutch 84 of a torque converter 83 is in a disengagement state, compared to when it is in a direct engagement state.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vehicle control device.

Patent Document 1 discloses a control device for a hybrid vehicle. In a hybrid vehicle, an electric motor, an engine, a connecting/disconnecting clutch provided between the electric motor and the engine, and a torque converter are provided on a power transmission path to the drive wheels. The torque converter is provided with a lockup clutch capable of directly connecting the input shaft and the output shaft of the torque converter. According to the control device disclosed in Patent Document 1, when the engine is started from the state where the vehicle is traveling with only the electric motor as the drive source, the lock-up clutch slips and the disconnecting clutch slips. The ignition starts the engine.

JP, 2014-73705, A

When the engine is started like the control device disclosed in Patent Document 1, the larger the difference between the rotation speed of the electric motor and the rotation speed of the engine, the larger the amount of heat generation in the disconnecting clutch. Here, the increasing speed of the rotation speed of the electric motor when the connecting/disconnecting clutch is in the released state changes according to the state of the lockup clutch. Specifically, when the lockup clutch is in the disengaged state, the rotation speed of the electric motor is likely to increase early. Therefore, when the engine is started while slipping the engagement/disengagement clutch when the lock-up clutch is in the released state, the amount of heat generated in the engagement/disengagement clutch is large due to the large difference between the rotation speed of the electric motor and the rotation speed of the engine. There is a risk of becoming. In the control device disclosed in Patent Document 1, it is premised that the lockup clutch is in the slipping state, and the case where the lockup clutch is in the releasing state is not considered.

A vehicle control device for solving the above-mentioned problems includes an engine of a vehicle, an electric motor provided on a power transmission path between the engine and drive wheels of the vehicle, the engine in the power transmission path, and the engine. The present invention is applied to a hybrid vehicle including a connection/disconnection clutch provided between an electric motor and a torque converter that is arranged between the electric motor and the drive wheels in the power transmission path and has a lockup clutch. A vehicle control unit that executes a travel mode changing process for starting the engine while controlling the engagement/disengagement clutch toward engagement when the vehicle is traveling by the electric motor with the engagement/disengagement clutch released. A rotation speed of the electric motor is larger than an engine start determination value, a differential rotation determination unit that allows the engine to start in the traveling mode change process, and the engine start when the lockup clutch is in a released state. The gist is to provide a determination value setting unit that sets a determination value smaller than the engine start determination value when the lockup clutch is in the direct engagement state.

According to the above configuration, when the lockup clutch is in the released state and the rotation speed of the electric motor tends to increase, that is, when the difference between the rotation speed of the electric motor and the rotation speed of the engine tends to increase, the lockup clutch is The engine start determination value is set smaller than that in the direct connection state. Therefore, when the lockup clutch is in the disengaged state, when the difference between the rotation speed of the electric motor and the rotation speed of the engine is smaller than when the lockup clutch is in the direct connection state, the engine start is permitted and the connection/disconnection is made. Clutch slip begins. As a result, it is possible to suppress an increase in the heat generation amount of the connecting/disconnecting clutch in the traveling mode changing process when the lockup clutch is in the released state.

The schematic diagram which shows one Embodiment of the control apparatus of a vehicle, and the vehicle which the same control apparatus controls. The flowchart which shows the process routine of the start determination process which the same control apparatus implements during implementation of a driving mode change process. The flowchart which shows the process routine of the determination value setting process which the same control device implements. The timing chart at the time of performing a driving mode change process in the control apparatus. The timing chart at the time of performing a driving mode change process in the control apparatus.

Hereinafter, a control device 10 as one embodiment of a vehicle control device will be described with reference to FIGS. 1 to 5.
FIG. 1 shows a control device 10 and a vehicle 90 that is a control target of the control device 10. The vehicle 90 is a hybrid vehicle that includes an engine 91 and an electric motor 82 as drive sources. The vehicle 90 includes a transmission unit 80 in a power transmission path from the engine 91 to the drive wheels 72. The transmission unit 80 and the drive wheels 72 are connected via a differential 71.

The transmission unit 80 includes an electric motor 82. The electric motor 82 is located on the power transmission path from the engine 91 to the drive wheels 72. The electric motor 82 is connected to a power source via an inverter. The electric motor 82 functions as a driving source that generates driving force for the vehicle by supplying electric power from a power source. Further, the electric motor 82 can also function as a generator that generates electric power by power transmission from the engine 91 or the drive wheels 72.

The transmission unit 80 includes a connection/disconnection clutch 81. The connecting/disconnecting clutch 81 is located between the engine 91 and the electric motor 82 on the power transmission path. The connecting/disconnecting clutch 81 is operated by the hydraulic pressure supplied from the hydraulic control mechanism 86 included in the transmission unit 80. When the engagement/disengagement clutch 81 is engaged, the crankshaft 92, which is the output shaft of the engine 91, is connected to the rotor of the electric motor 82. When the connecting/disconnecting clutch 81 is released, the crankshaft 92 and the rotor of the electric motor 82 are separated.

The transmission unit 80 includes a torque converter 83 and an automatic transmission 85. The automatic transmission 85 is located closer to the drive wheels 72 than the electric motor 82 on the power transmission path. The automatic transmission 85 is connected to the electric motor 82 via the torque converter 83.

The torque converter 83 includes a pump impeller 83A on the input side and a turbine liner 83B on the output side. The pump impeller 83A rotates integrally with the input shaft to which the power from the engine 91 and the electric motor 82 is input. The turbine liner 83B rotates integrally with the output shaft connected to the automatic transmission 85. In the torque converter 83, torque is transmitted via a fluid between the pump impeller 83A and the turbine liner 83B.

Further, the torque converter 83 includes a lock-up clutch 84 that can directly connect the pump impeller 83A and the turbine liner 83B to rotate them integrally. The lockup clutch 84 is operated by the hydraulic pressure supplied from the hydraulic control mechanism 86. The operating states of the lockup clutch 84 include a direct connection state, a released state, and a slip state. The direct connection state is a state in which the pump impeller 83A and the turbine liner 83B are directly connected via the lockup clutch 84. The released state is a state in which the lockup clutch 84 is released. The slip state is a state in which the lockup clutch 84 is slipping. In the slip state, the flex lockup control is performed to control the slip amount of the lockup clutch 84. The control device 10 performs the flex lockup control.

The mode of torque transmission by the torque converter 83 is switched depending on the state of the lockup clutch 84. When the lock-up clutch 84 is in the direct connection state, the pump impeller 83A and the turbine liner 83B rotate integrally to transmit torque from the input shaft to the output shaft. When the lockup clutch 84 is in the disengaged state, the amount of torque transmission through the lockup clutch 84 becomes “0”, and the torque is transmitted between the pump impeller 83A and the turbine liner 83B through the fluid, whereby the input shaft is transmitted. Torque is transmitted from the motor to the output shaft. When the lockup clutch 84 is in the slip state, the amount of torque transmitted through the lockup clutch 84 is adjusted by the flex lockup control. Specifically, when the slip amount is small, the difference between the rotation speed of the pump impeller 83A and the rotation speed of the turbine liner 83B tends to be small, and when the slip amount is large, the rotation speed of the pump impeller 83A and the turbine liner 83B. The difference from the number of rotations of is likely to be large.

In the vehicle 90, the traveling mode can be changed by switching between the EV traveling mode in which only the electric motor 82 is used as a drive source and the engine traveling mode in which the power of the engine 91 is transmitted to the drive wheels 72. In the EV traveling mode, the connection/disconnection clutch 81 is released and the engine 91 is not driven. The change of the driving mode is performed by the control device 10 of the vehicle 90.

The control device 10 controls the engine 91, the electric motor 82, and the hydraulic control mechanism 86. The control device 10 includes a vehicle control unit 11, a differential rotation determination unit 12, and a determination value setting unit 13 as functional units.

The vehicle control unit 11 changes the traveling mode of the vehicle 90 by executing the traveling mode changing process according to the increase in the required drive amount of the vehicle 90. When the start of the engine 91 is permitted during the execution of the traveling mode changing process, the EV traveling mode is changed to the engine traveling mode. When the traveling mode of the vehicle 90 is changed from the EV traveling mode to the engine traveling mode, the vehicle control unit 11 operates the engagement/disengagement clutch 81 in a direction to be engaged. Then, the vehicle control unit 11 slips the connection/disconnection clutch 81 and rotates the crankshaft 92 to start ignition of the engine 91 and start the engine 91. When the engagement/disengagement clutch 81 is completed, the electric motor 82 and the engine 91 are synchronized with each other.

Based on the difference between the MG rotation speed Nm that is the rotation speed of the electric motor 82 and the ENG rotation speed Ne that is the rotation speed of the engine 91, the differential rotation determination unit 12 starts the engine 91 during the running mode change process. A start determination process is performed to determine whether to permit. Hereinafter, the magnitude of the difference between the MG rotation speed Nm and the ENG rotation speed Ne may be referred to as “differential rotation”.

The determination value setting unit 13 performs a determination value setting process that sets the value of the ENG startup determination value Nkth used in the startup determination process according to the state of the lockup clutch 84.
The start determination process performed by the differential rotation determination unit 12 will be described with reference to FIG. This processing routine is repeatedly executed after the running mode change processing is started until the engine 91 is started.

When this processing routine is executed, first, in step S101, it is determined whether or not the MG rotational speed Nm is larger than the ENG start determination value Nkth. Here, before the start of the engine 91 is started, the ENG rotation speed Ne is “0”. Therefore, the MG rotation speed Nm at this time is equal to the difference between the rotation speed of the electric motor 82 and the rotation speed of the engine 91. Further, the ENG start determination value Nkth is a value for determining whether or not the start of the engine 91 may be started in the traveling mode changing process. The ENG start determination value Nkth is set by the determination value setting unit 13 as described later.

If the MG rotational speed Nm is equal to or lower than the ENG start determination value Nkth (S101: NO), this processing routine is once ended. On the other hand, when the MG rotation speed Nm is larger than the ENG start determination value Nkth (S101: YES), the process proceeds to step S102. In step S102, starting of the engine 91 is permitted. That is, in the differential rotation determination unit 12, the difference between the MG rotation speed Nm that is the rotation speed of the electric motor 82 and the ENG rotation speed Ne that is the rotation speed of the engine 91 is larger than the ENG start determination value Nkth as the engine start determination value. At some times, starting of the engine 91 in the traveling mode changing process is permitted. When the start of the engine 91 is permitted in step S102, this processing routine ends.

Next, with reference to FIG. 3, a judgment value setting process executed by the judgment value setting unit 13 will be described. This processing routine is repeatedly executed every predetermined period.
When this processing routine is executed, first in step S201, it is determined whether or not the lockup clutch 84 is in the direct engagement state. When the lockup clutch 84 is in the direct connection state (S201: YES), the process proceeds to step S202. In step S202, the first determination value Nkth1 is set as the ENG start determination value Nkth. Then, this processing routine is ended.

On the other hand, in the process of step S201, when the lockup clutch 84 is not in the direct engagement state (S201: NO), the process proceeds to step S203. In step S203, it is determined whether the lockup clutch 84 is in the slip state. When the lockup clutch 84 is in the slip state (S203: YES), the process proceeds to step S204. In step S204, the second determination value Nkth2 is set as the ENG start determination value Nkth. Then, this processing routine is ended.

On the other hand, in the process of step S203, if the lockup clutch 84 is not in the slipping state (S203: NO), the process proceeds to step S205. That is, when the lockup clutch 84 is in the released state, the process proceeds to step S205. In step S205, the third determination value Nkth3 is set as the ENG start determination value Nkth. Then, this processing routine is ended.

The first to third determination values Nkth1 to 3 set as the ENG start determination value Nkth are when the difference between the MG rotational speed Nm and the ENG rotational speed Ne becomes larger than the determination value during the execution of the traveling mode changing process. When the operation of the connecting/disconnecting clutch 81 is started, the value is set to a value that can suppress an increase in the heat generation amount of the connecting/disconnecting clutch 81. The first to third determination values Nkth1 to 3 are calculated in advance by experiments or the like according to the state of the lockup clutch 84, and are stored in the determination value setting unit 13. The second determination value Nkth2 is a value smaller than the first determination value Nkth1. The third determination value Nkth3 is a value smaller than the second determination value Nkth2. Therefore, among the first to third determination values Nkth1 to 3, the first determination value Nkth1 is the largest value and the third determination value Nkth3 is the smallest value. That is, the determination value setting unit 13 sets the ENG startup determination value Nkth when the lockup clutch 84 is in the released state to be smaller than the ENG startup determination value Nkth when the lockup clutch 84 is in the direct connection state. In this way, the determination value setting process performed by the determination value setting unit 13 switches the value of the ENG start determination value Nkth based on the state of the lockup clutch 84.

The operation and effect of this embodiment will be described.
First, the travel mode changing process performed when the lockup clutch 84 is in the direct engagement state will be described with reference to FIG. In FIG. 4, the MG rotation speed Nm is shown by a solid line, and the ENG rotation speed Ne is shown by a two-dot chain line. The MG rotation speed Nm gradually increases based on the required drive amount. The ENG rotation speed Ne is "0" before the timing t2. Therefore, before the timing t2, the MG rotation speed Nm is equal to the difference between the MG rotation speed Nm and the ENG rotation speed Ne. Further, since the lockup clutch 84 is in the direct engagement state, the first determination value Nkth1 is set as the ENG start determination value Nkth by the processing of step S202 in the determination value setting processing.

When the MG rotation speed Nm becomes larger than the first determination value Nkth1 at the timing t1, the start of the engine 91 is permitted by the process of step S102 in the start determination process. When the start of the engine 91 is permitted, the vehicle control unit 11 changes the traveling mode to the engine traveling mode. The vehicle control unit 11 starts the operation of the connecting/disconnecting clutch 81 at timing t1 in order to engage the connecting/disconnecting clutch 81.

In the period from the timing t1 to the timing t2, the connection/disconnection clutch 81 is operated from the released state to the slip state. At timing t2, the connecting/disconnecting clutch 81 starts slipping. When the connecting/disconnecting clutch 81 starts slipping at timing t2, the rotation of the electric motor 82 is transmitted to the engine 91, and the ENG rotation speed Ne starts increasing. After timing t2, the vehicle control unit 11 starts ignition of the engine 91 and increases the ENG speed Ne. After timing t3, the engagement/disengagement clutch 81 is engaged, and the MG rotation speed Nm and the ENG rotation speed Ne are synchronized.

Next, with reference to FIG. 5, a travel mode changing process performed when the lockup clutch 84 is in the released state will be described. In FIG. 5, the MG rotational speed Nm and the ENG rotational speed Ne when the lockup clutch 84 is in the disengaged state are shown by a solid line and a chain double-dashed line, respectively. The MG rotation speed Nm gradually increases based on the required drive amount. Note that, in FIG. 5, as a comparative example, the MG rotational speed Nm when the lockup clutch 84 is in the direct engagement state is shown by a broken line. In the example shown by the solid line in which the lockup clutch 84 is in the released state, the increasing speed of the MG rotational speed Nm is higher than that in the example shown by the broken line. The ENG rotation speed Ne is "0" before the timing t12. Therefore, before the timing t12, the MG rotation speed Nm is equal to the difference between the MG rotation speed Nm and the ENG rotation speed Ne. Further, since the lockup clutch 84 is in the released state, the third determination value Nkth3, which is a value smaller than the first determination value Nkth1, is set as the ENG start determination value Nkth by the processing of step S205 in the determination value setting processing. There is.

When the MG rotational speed Nm indicated by the solid line becomes larger than the third determination value Nkth3 at the timing t11, the start of the engine 91 is permitted by the process of step S102 in the start determination process. When the start of the engine 91 is permitted, the vehicle control unit 11 changes the traveling mode to the engine traveling mode. The vehicle control unit 11 starts the operation of the connecting/disconnecting clutch 81 at timing t11 in order to engage the connecting/disconnecting clutch 81.

In the period from the timing t11 to the timing t12, the connection/disconnection clutch 81 is operated from the released state to the slip state. At timing t12, the connecting/disconnecting clutch 81 starts slipping. It should be noted that a prescribed period depending on the increasing speed of the hydraulic pressure is required from the start of operation of the connecting/disconnecting clutch 81 to the start of slipping of the connecting/disconnecting clutch 81. Therefore, the length of the period from timing t11 to timing t12 in the example of FIG. 5 is equal to the length of the period from timing t1 to timing t2 in the example of FIG. When the connecting/disconnecting clutch 81 starts slipping at the timing t12, the rotation of the electric motor 82 is transmitted to the engine 91, so that the ENG rotation speed Ne starts to increase. After timing t12, the vehicle control unit 11 starts ignition of the engine 91 and increases the ENG speed Ne. After timing t13, the engagement/disengagement clutch 81 is engaged, and the MG rotational speed Nm shown by the solid line and the ENG rotational speed Ne shown by the two-dot chain line are synchronized.

When the lockup clutch 84 is in the disengaged state as illustrated by the solid line in FIG. 5, the MG rotation speed is higher than when the lockup clutch 84 is in the directly connected state as illustrated by the broken line. The increase speed of Nm is large. According to the control device 10, when the lockup clutch 84 is in the disengaged state, the third judgment value Nkth3 smaller than the first judgment value Nkth1 set when the lockup clutch 84 is in the direct connection state is used for the traveling mode changing process. Used for. Therefore, starting of the engine 91 is permitted from the time when the MG rotational speed Nm is small, that is, the time when the differential rotation is small. As a result, it is possible to prevent the differential rotation from becoming large at the time when the connecting/disconnecting clutch 81 starts slipping even in a state where the increasing speed of the MG rotation speed Nm is large. That is, it is possible to suppress an increase in the amount of heat generated by the connecting/disconnecting clutch 81 in the traveling mode changing process when the lockup clutch 84 is in the released state.

On the other hand, when the lockup clutch 84 is in the direct engagement state, the increasing speed of the MG rotational speed Nm becomes smaller as illustrated in FIG. 4 than when it is in the disengagement state. According to the control device 10, in the traveling mode changing process that is performed when the lockup clutch 84 is in the direct connection state, the control device 10 is greater than the third determination value Nkth3 that is set when the lockup clutch 84 is in the released state. 1 judgment value Nkth1 is used. Further, in the traveling mode changing process that is performed when the lockup clutch 84 is in the slipping state, the second determination value Nkth2 that is an intermediate value between the first determination value Nkth1 and the third determination value Nkth3 is used. As a result, when the lockup clutch 84 is in the direct engagement state or the slip state, starting of the engine 91 is permitted from the time when the MG rotational speed Nm increases as compared to when the lockup clutch 84 is in the released state.

If the third determination value Nkth3 is used also in the traveling mode change process that is performed when the lockup clutch 84 is in the direct connection state or the slip state, compared to when the lockup clutch 84 is in the released state. The MG rotational speed Nm at the time when the connecting/disconnecting clutch 81 starts slipping becomes small. For example, FIG. 5 shows a broken line in which the MG rotational speed Nm reaches the third determination value Nkth3 at timing t11, as in the case of the solid line in the released state, as an example of the case where the lockup clutch 84 is in the direct connection state. ing. In the example indicated by the broken line, the MG rotational speed Nm at the timing t12 at which the connecting/disconnecting clutch 81 starts slipping if the connecting/disconnecting clutch 81 is temporarily operated from the timing t11 is smaller than that in the example indicated by the solid line. Therefore, if the third determination value Nkth3 is used as the ENG start determination value Nkth when the lockup clutch 84 is in the direct engagement state or the slip state, the slip of the connection/disconnection clutch 81 is used to determine the ENG rotation speed Ne. Hard to raise. In this regard, according to the control device 10, when the lock-up clutch 84 is in the direct engagement state or the slip state, the engine 91 is permitted to start from the time when the MG rotational speed Nm increases. As a result, the MG rotational speed Nm at the time when the connecting/disconnecting clutch 81 starts slipping can be increased.

The present embodiment can be modified and implemented as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
In the determination value setting process in the above embodiment, the second determination value Nkth2 is a constant value. The second determination value Nkth2 may be set to a value calculated as a variable value in a range smaller than the first determination value Nkth1 and larger than the third determination value Nkth3 based on the slip amount of the lockup clutch 84. For example, in the state where the connecting/disconnecting clutch 81 is released, the increasing speed of the MG rotation speed Nm tends to increase as the slip amount increases. Therefore, the larger the slip amount, the smaller the second determination value Nkth2 may be calculated.

In the traveling mode changing process in the above-described embodiment, it is determined whether the MG rotation speed Nm is larger than the ENG start determination value Nkth, and if the MG rotation speed Nm is larger than the ENG start determination value Nkth, the engine 91 is operated. I am trying to allow the start. Instead, it is determined whether the MG rotation speed Nm is larger than the value obtained by adding the ENG rotation speed Ne to the ENG start determination value Nkth, and the MG rotation speed Nm is changed to the ENG start determination value Nkth. It is also possible to permit the starting of the engine 91 when the value is larger than the value obtained by adding. That is, it may be determined whether or not the difference in rotation speed between the MG rotation speed Nm and the ENG rotation speed Ne is larger than the ENG start determination value Nkth. In this case, the value obtained by adding the ENG rotation speed Ne to the ENG start determination value Nkth corresponds to the engine start determination value.

DESCRIPTION OF SYMBOLS 10... Control device, 11... Vehicle control part, 12... Differential rotation determination part, 13... Determination value setting part, 71... Differential, 72... Drive wheel, 80... Transmission unit, 81... Disconnection clutch, 82... Electric motor, 83 ... torque converter, 83A... pump impeller, 83B... turbine liner, 84... lockup clutch, 85... automatic transmission, 86... hydraulic control mechanism, 90... vehicle, 91... engine, 92... crankshaft.

Claims (1)

The vehicle engine,
An electric motor provided on the power transmission path between the engine and the drive wheels of the vehicle,
An engagement/disengagement clutch provided between the engine and the electric motor in the power transmission path,
It is arranged between the electric motor and the drive wheels in the power transmission path, and is applied to a hybrid vehicle including a torque converter having a lockup clutch,
When the vehicle is traveling by the electric motor in a state where the connection/disconnection clutch is released, a vehicle control unit that executes a travel mode changing process for starting the engine while controlling the connection/disconnection clutch toward engagement.
A differential rotation speed determination unit that permits starting of the engine in the traveling mode change process when the rotation speed of the electric motor is higher than an engine start determination value;
A vehicle control system, comprising: a determination value setting unit configured to set the engine start determination value when the lockup clutch is in a released state to be smaller than the engine start determination value when the lockup clutch is in a direct connection state. apparatus.