JP7707936B2 - Hybrid vehicle control method - Google Patents

Description

The present invention relates to a method for controlling a hybrid vehicle, and in particular to a method for controlling a hybrid vehicle equipped with an engine and a rotating electric machine.

Hybrid vehicles are known that stop or start the engine while traveling. In such hybrid vehicles, when there is a request to start the engine, a start control may be performed in which a clutch provided in the drive system is engaged to drive a rotating electric machine and crank the engine.

Patent Document 1 discloses a hybrid vehicle in which a clutch is provided between the engine and the motor, and clutch engagement pressure is supplied from a control valve provided in a line pressure circuit through which a mechanical pump discharges hydraulic fluid, and which is characterized by having a start control unit that executes start control to start the engine by engaging the first clutch and inputting torque from the motor to the engine when an engine start request is made during EV driving driven by the motor, and a start determination unit included in the start control unit that calculates a transmission input torque, which is an input torque to the automatic transmission, and executes start control when this transmission input torque exceeds a set input torque that is preset based on the hydraulic fluid pressure.

Patent No. 5888429

In controlling hybrid vehicles, it is desirable to expand the EV driving range in which EV driving can be performed with the engine stopped and the vehicle running using only the rotating electric machine as a driving force source. For example, the maximum motor torque may be set for the torque output from the rotating electric machine during EV driving so that a torque sufficient to start the stopped engine can be output. However, with the technology described in Patent Document 1, once the maximum motor torque and the cranking torque required for cranking the engine are determined, the engine start determination torque (EV driving range) is uniquely determined, which causes a problem in that the EV driving range becomes narrower depending on the setting of the maximum motor torque.

The present invention has been made to solve these problems, and aims to provide a control method for a hybrid vehicle that can expand the EV driving range.

The control method for a hybrid vehicle according to one embodiment is a control method for a hybrid vehicle equipped with an engine and a rotating electric machine, and includes the steps of: calculating a basic maximum motor torque determined by the rotation speed of the rotating electric machine and the input voltage of an inverter that drives the rotating electric machine; calculating a temporary increase torque that can temporarily increase the maximum motor torque of the rotating electric machine before cranking the engine; setting the motor torque obtained by adding the temporary increase torque to the basic maximum motor torque as the maximum motor torque during engine cranking; and calculating an engine start determination torque used for engine start determination based on the set maximum motor torque during cranking.

The present invention provides a method for controlling a hybrid vehicle that can expand the EV driving range.

1 is a configuration diagram showing a hybrid vehicle according to a first embodiment; 4 is a flowchart showing a control method for a hybrid vehicle according to the first embodiment. FIG. 13 is a diagram illustrating a map for calculating MTb. 1 is a graph illustrating an estimated temperature and an upper limit temperature of a target component. 11 is a flowchart illustrating in detail the process (step S20) of determining whether or not temporary upload is possible. FIG. 13 is a diagram illustrating a table for calculating MTup. 11 is a flowchart illustrating details of a process (step S80) for calculating an actual maximum motor torque MTmax. FIG. 11 is a configuration diagram showing another embodiment of a hybrid vehicle.

First embodiment
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In order to clarify the description, the following description and drawings are appropriately simplified. What is shown in the drawings is only a part of the whole, and in reality, many other configurations that are not shown are included. Furthermore, in the following description, the same or equivalent elements are given the same reference numerals, and duplicated descriptions are omitted.

First, the system configuration of a hybrid vehicle 100 according to this embodiment will be described with reference to FIG. 1. FIG. 1 is a configuration diagram showing a hybrid vehicle according to the first embodiment. FIG. 1 shows a schematic configuration of the main parts of the hybrid vehicle 100, with the left side showing the state during EV driving and the right side showing the state during engine start processing (cranking) when transitioning from EV driving to HEV driving. The engine start processing is the processing from when a request to start engine 1 is made to start engine 1 until the start of engine 1 is completed.

The hybrid vehicle 100 shown in FIG. 1 is a parallel hybrid vehicle equipped with an engine 1 and a rotating electric machine 2 as driving force sources. The hybrid vehicle 100 is equipped with an engine 1, a first clutch K0, a rotating electric machine 2, a second clutch WSC, a transmission 3, and driving wheels 4. The engine 1 is connected to the rotating electric machine 2, the second clutch WSC, the transmission 3, and driving wheels 4 via the first clutch K0. In addition, the rotating electric machine 2 is connected to the transmission 3 and driving wheels 4 via the second clutch WSC.

In other words, the rotating electric machine 2 is disposed closer to the drive wheels 4 than the engine 1. The first clutch K0 can connect and disconnect the engine 1 and the rotating electric machine 2, and the second clutch WSC can connect and disconnect the rotating electric machine 2 and the transmission 3.

The engine 1 is an internal combustion engine such as a gasoline engine or a diesel engine. The engine 1 converts the combustion energy of fuel into the rotational motion of the crankshaft 1a and outputs the motion. The engine torque, which is the output torque of the engine 1, is transmitted to the drive wheels 4 via the first clutch K0, the rotating electric machine 2, the second clutch WSC, the transmission 3, and the drive shaft 4a.

The first clutch K0 is a clutch interposed between the crankshaft 1a of the engine 1 and the rotating shaft 2a of the rotating electric machine 2. The first clutch K0 is, for example, a wet multi-plate clutch, which connects the engine 1 and the rotating electric machine 2 in an engaged state and disconnects the engine 1 and the rotating electric machine 2 in a released state.

The rotating electric machine 2 has a function as a motor (electric motor) and a function as a generator. The rotating electric machine 2 is connected to a battery provided in the hybrid vehicle 100 via an inverter provided in the hybrid vehicle 100. The rotating electric machine 2 generates driving power from electric power supplied from the battery via an inverter that drives the rotating electric machine 2, instead of or in addition to the engine 1. The rotating electric machine 2 converts the power of the engine 1 and the driven force input from the driving wheels 4 side into electric power by regeneration, and stores the electric power in the battery via the inverter. In this embodiment, the rotating electric machine 2 is a synchronous motor generator with a permanent magnet embedded in the rotor and a stator coil wound around the stator.

The second clutch WSC is a clutch interposed between the rotating electric machine 2 and the drive wheels 4. The second clutch WSC shown in FIG. 1 is provided on the input shaft 3a of the transmission 3 and is interposed between the rotating electric machine 2 and the transmission 3. The second clutch WSC is a wet multi-plate clutch that also functions as a starting clutch, for example, and connects the rotating electric machine 2 and the transmission 3 in an engaged state and disconnects the rotating electric machine 2 and the transmission 3 in a released state.

The transmission 3 is an automatic transmission, for example, a stepped automatic transmission (A/T). However, the transmission 3 is not limited to this, and may be a continuously variable automatic transmission (CVT) or the like. The output shaft 3b of the transmission 3 is connected to the drive wheels 4 via the drive shaft 4a. It is preferable that a differential mechanism is provided between the output shaft 3b of the transmission 3 and the drive shaft 4a.

The hybrid vehicle 100 is equipped with an electronic control unit (ECU) capable of executing the hybrid vehicle control method according to this embodiment. The ECU is configured to include a so-called microcomputer equipped with, for example, a CPU (Central Processing Unit), a storage device, and an input/output interface. The storage device includes a RAM (Random Access Memory) as a working memory, and a ROM (Read Only Memory) as a storage device for saving. The storage device may be a rewritable non-volatile memory or the like. The CPU reads out a program stored in the ROM, expands it into the RAM, and executes various processes according to the expanded program to execute various controls performed by the ECU.

The ECU is connected to the engine 1, the first clutch K0, the rotating electric machine 2, the second clutch WSC, the transmission 3, etc., and can control these. For example, the ECU is configured to execute output control of the engine 1, drive control of the rotating electric machine 2, shift control of the transmission 3, torque capacity control (engagement and release control) of the first clutch K0 and the second clutch WSC, etc.

The hybrid vehicle 100 can selectively switch between EV driving, HEV driving, and WSC (Wet Start Clutch) driving, which are different drive modes. The EV driving mode (electric vehicle driving mode) is a driving mode in which the hybrid vehicle 100 is driven using only the power of the rotating electric machine 2 as a driving force source with the first clutch K0 in an open state. The HEV driving mode (engine-use driving mode) is a driving mode in which the hybrid vehicle 100 is driven while the first clutch K0 is in an engaged state and the engine 1 is included in the driving force source. The WSC driving mode (engine-use slip driving mode) is a driving mode in which the hybrid vehicle 100 is driven while the first clutch K0 is in an engaged state and the second clutch WSC is in a half-engaged state, and the hybrid vehicle 100 is driven while the engine 1 is included in the driving force source.

Furthermore, HEV driving includes driving using only the engine 1 as the driving force source, driving using both the engine 1 and the rotating electric machine 2 as the driving force source, and driving using the engine 1 as the driving force source while generating a reaction force in the rotating electric machine 2 through regenerative control.

When the first clutch K0 and the second clutch WSC each have a hydraulic actuator, the ECU controls the degree of engagement (torque capacity) of each of the first clutch K0 and the second clutch WSC by adjusting the supplied hydraulic pressure. In other words, by changing the torque capacity of each of the first clutch K0 and the second clutch WSC, each of the first clutch K0 and the second clutch WSC can be controlled to be in either an engaged state, a half-engaged state (slip state), or a released state.

During EV driving, the ECU controls the first clutch K0 to be in a released state and the second clutch WSC to be in an engaged state, and in this state causes the rotating electric machine 2 to output the motor torque required for EV driving. During HEV driving, the ECU controls the first clutch K0 and the second clutch WSC to be in an engaged state, and controls the engine torque of the engine 1 and the motor torque of the rotating electric machine 2 to output the engine torque and motor torque.

When switching from EV driving to HEV driving, the ECU performs start control of the engine 1. In the start control of the engine 1, the ECU performs a process of controlling the inverter so that the rotating electric machine 2 outputs a cranking torque MTcr for cranking the engine 1 via the first clutch K0. Then, when the rotation speed of the engine 1 (engine speed) reaches a predetermined rotation speed by cranking via the first clutch K0, the ECU performs a process of starting fuel injection control and ignition control of the engine 1. This completes the start of the engine 1. When switching from EV driving to HEV driving, the first clutch K0 is put into a half-engagement state to transmit the cranking torque MTcr to the engine 1, and the engine speed is gradually increased to start the engine 1.

In the hybrid vehicle control method according to this embodiment, the maximum motor torque MTmax that can be output from the rotating electric machine 2 is temporarily increased during the start-up process (cranking) of the engine 1. This makes it possible to expand the EV driving range.

In addition, in the hybrid vehicle control method according to this embodiment, if the estimated temperature of a target component that may become overheated if the maximum motor torque MTmax is temporarily increased when the engine 1 starts is expected to exceed a preset upper limit temperature of the target component, the temporary increase in the maximum motor torque MTmax is prohibited. This makes it possible to prevent damage to the component (target component) that may occur due to overheating, and to protect the component.

FIG. 2 is a flowchart showing the control method for a hybrid vehicle according to the first embodiment. As shown in FIG. 2, the processing of steps S10 to S80 in the control method for a hybrid vehicle according to this embodiment is executed by the ECU.

First, in step S10, the ECU calculates the basic maximum motor torque MTb, which is determined by the rotation speed (motor rotation speed) of the rotating electric machine 2 and the input voltage of the inverter that drives the rotating electric machine 2. The basic maximum motor torque MTb can be calculated from the motor rotation speed and the input voltage by referring to a predetermined MTb calculation map.

Here, FIG. 3 is a diagram for explaining the MTb calculation map. The MTb calculation map shown in FIG. 3 illustrates three types of MTb curves according to the input voltage of the inverter. The solid line shown in FIG. 3 is an MTb curve showing the relationship between the motor rotation speed and the basic maximum motor torque MTb when the input voltage is V1. The dashed line shown in FIG. 3 is an MTb curve showing the relationship between the motor rotation speed and the basic maximum motor torque MTb when the input voltage is V2. The two-dot dashed line shown in FIG. 3 is an MTb curve showing the relationship between the motor rotation speed and the basic maximum motor torque MTb when the input voltage is V3. Note that the input voltages V1, V2, and V3 are V1<V2<V3.

The MTb calculation map is created in advance through experiments, analysis, etc. The MTb calculation map sets the relationship between the motor speed and the basic maximum motor torque MTb for each input voltage. It is preferable that the basic maximum motor torque MTb included in the MTb calculation map is set to a motor torque that the rotating electric machine 2 can continuously output over a relatively long period of time (e.g., approximately 5 minutes or more).

The MTb calculation map is stored in a storage means such as a ROM of the ECU. In step S10, when a request to start the engine 1 is made, the ECU refers to the MTb calculation map and performs a process to derive the basic maximum motor torque MTb corresponding to the current motor rotation speed and the current input voltage.

In step S20, the ECU performs a process for determining whether or not the maximum motor torque MTmax can be temporarily increased for target components that may become overheated due to engine cranking by comparing the estimated temperature of the target components during cranking with a preset upper limit temperature of the target components. The estimated temperature and upper limit temperature will now be described with reference to FIG. 4. FIG. 4 is a graph illustrating the estimated temperature and upper limit temperature of the target components.

In this embodiment, the target components are an inverter that drives the rotating electric machine 2 and the rotating electric machine 2. Here, as the estimated temperature and upper limit temperature of the inverter, for example, the estimated temperature Twat0 and upper limit temperature Twat1 of the inverter cooling water temperature Twat, and the estimated temperature Tinv0 and upper limit temperature Tinv1 of the temperature of the inverter element (inverter element temperature Tinv) included in the inverter can be used. As the estimated temperature and upper limit temperature of the rotating electric machine 2, for example, the estimated temperature Tco0 and upper limit temperature Tco1 of the temperature of the stator coil (stator coil temperature Tco) can be used.

The upper graph in Figure 4 shows, as an example of temperature rise data, a predicted change over time in inverter element temperature Tinv associated with the engine start process. The lower graph in Figure 4 shows a predicted change over time in motor torque associated with the engine start process.

The solid line in the graph showing the change over time in inverter element temperature Tinv is the actual measured temperature during EV driving, and the dotted line is the estimated temperature Tinv0 after the engine start process begins. The solid line in the graph showing the change over time in motor torque is the actual measured motor torque during EV driving, and the dotted line shows the progress of motor torque when it is assumed that the maximum motor torque MTmax is temporarily increased during the engine start process.

If the time required to start engine 1 (start-up time from the start of engine start processing to completion of engine 1 startup) is known, it is possible to predict the change in inverter element temperature Tinv after the start of engine start processing (during engine start processing and when driving in HEV mode) from the actual measured inverter element temperature Tinv during EV driving and the inverter coolant temperature Twat, assuming that the maximum motor torque MTmax is temporarily increased during engine start-up.

Figure 4 shows an example in which the inverter element temperature Tinv rises from time P1, which is the start of the engine start process, and the estimated temperature Tinv0 reaches the upper limit temperature Tinv1 at time P2, when the vehicle switches to HEV driving as the start of the engine 1 is completed.

Similarly, if the time required to start engine 1 is known, assuming that the maximum motor torque MTmax is temporarily increased during the engine start process, it is possible to predict the change in stator coil temperature Tco after the start of the engine start process from the actual measured temperature of stator coil temperature Tco during EV driving, and it is possible to predict the change in inverter cooling water temperature Twat after the start of the engine start process from the actual measured temperature of inverter cooling water temperature Twat during EV driving.

On the other hand, the upper limit temperature of the target component should be set to a temperature at which the target component will not overheat during engine start processing, even if the maximum motor torque MTmax is temporarily increased, taking into consideration, for example, the heat resistance temperature when the target component is mounted. In this embodiment, the upper limit temperatures Twat1, Tinv1, and Tco1 are set for the inverter cooling water temperature Twat, inverter element temperature Tinv, and stator coil temperature Tco, respectively, and the process flow for determining whether or not to temporarily increase is explained using an example in which the upper limit temperatures are compared with the corresponding estimated temperatures Twat0, Tinv0, and Tco0.

Figure 5 is a flowchart that explains in detail the process of determining whether or not a temporary upgrade is possible (step S20). As shown in Figure 5, in step S20, the ECU executes the processes of steps S21 to S25.

In step S21, the estimated temperature Twat0 of the inverter cooling water temperature Twat is compared with the upper limit temperature Twat1 of the inverter cooling water temperature Twat to determine whether the estimated temperature Twat0 is equal to or lower than the upper limit temperature Twat1. If the estimated temperature Twat0 is equal to or lower than the upper limit temperature Twat1 (Twat0≦Twat1) (step S21; YES), proceed to step S22. If the estimated temperature Twat0 exceeds the upper limit temperature Twat1 (Twat0>Twat1) (step S21; NO), proceed to step S25.

In step S22, the estimated temperature Tinv0 of the inverter element temperature Tinv is compared with the upper limit temperature Tinv1 of the inverter element temperature Tinv, and it is determined whether the estimated temperature Tinv0 is equal to or lower than the upper limit temperature Tinv1. If the estimated temperature Tinv0 is equal to or lower than the upper limit temperature Tinv1 (Tinv0≦Tinv1) (step S22; YES), proceed to step S23. If the estimated temperature Tinv0 exceeds the upper limit temperature Tinv1 (Tinv0>Tinv1) (step S22; NO), proceed to step S25.

In step S23, the estimated temperature Tco0 of the stator coil temperature Tco is compared with the upper limit temperature Tco1 of the stator coil temperature Tco to determine whether the estimated temperature Tco0 is equal to or lower than the upper limit temperature Tco1. If the estimated temperature Tco0 is equal to or lower than the upper limit temperature Tco1 (Tco0≦Tco1) (step S23; YES), proceed to step S24. If the estimated temperature Tco0 exceeds the upper limit temperature Tco1 (Tco0>Tco1) (step S23; NO), proceed to step S25.

If it is confirmed in steps S21 to S23 that the estimated temperature of each target component is equal to or lower than its respective upper limit temperature, it is determined in step S24 that the maximum motor torque MTmax can be temporarily increased, and the process proceeds to step S30. On the other hand, if it is confirmed in steps S21 to S23 that the estimated temperature of at least one target component exceeds its upper limit temperature, it is determined in step S25 that the maximum motor torque MTmax cannot be temporarily increased, and the process proceeds to step S30.

Next, in step S30, if the ECU determines that the maximum motor torque MTmax can be temporarily increased (step S30; YES), it proceeds to step S40, and if it determines that the maximum motor torque MTmax cannot be temporarily increased (step S30; NO), it proceeds to step S60.

In step S40, the ECU calculates a temporary increase torque MTup that can temporarily increase the maximum motor torque MTmax of the rotating electric machine 2 before cranking the engine 1. The temporary increase torque MTup can be calculated from the temperature of at least one target component by referring to a predetermined MTup calculation table.

For example, the case where the temporary up torque MTup is calculated from the inverter cooling water temperature Twat will be described as an example. FIG. 6 is a diagram illustrating a MTup calculation table. The MTup calculation table is created in advance through experiments, analysis, etc. The MTup calculation table sets the relationship between an arbitrary inverter cooling water temperature Twat and the temporary up torque MTup. It is preferable that the temporary up torque MTup included in the MTup calculation table is set to a motor torque that can be output by the rotating electric machine 2 only for a short period of time (e.g., approximately one minute) while the engine start process is being executed.

The MTup calculation table is stored in a storage device such as the ROM of the ECU. In step S40, the ECU refers to the MTup calculation table and performs a process to derive the corresponding temporary up-torque MTup from the current inverter cooling water temperature Twat.

In step S50, the ECU sets the motor torque obtained by adding the temporary up torque MTup to the basic maximum motor torque MTb as the maximum motor torque MTmax1 during cranking (the maximum motor torque MTmax temporarily increased for calculating the engine start judgment torque MTst), as shown in the following equation (1).
MTmax1←MTb+MTup...Formula (1)
Then, proceed to step S70.

On the other hand, in step S60, the ECU sets the basic maximum motor torque MTb as the maximum motor torque MTmax1 during cranking (the maximum motor torque MTmax that has not been temporarily increased for calculating the engine start judgment torque MTst), as shown in the following equation (2).
MTmax1←MTb...Formula (2)
Then, proceed to step S70.

The maximum motor torque MTmax1 set in steps S50 and S60 is the maximum motor torque MTmax when it is assumed that the engine is in the process of starting, regardless of whether the engine is currently in the process of starting. Then, in step S70, the ECU calculates the engine start determination torque MTst used for engine 1 start determination based on the maximum motor torque MTmax1 set in step S50 or step S60.

Here, the engine start determination torque MTst is a threshold value for determining a transition from EV driving to HEV driving. The engine start determination torque MTst can be calculated by subtracting the cranking torque MTcr and the margin torque MTmar from the maximum motor torque MTmax1, as shown in the following formula (3). The margin torque MTmar is appropriately set according to the amount of change in driving force expected during the engine start process, etc.
MTst←MTmax1-MTcr-MTmar...Formula (3)
By determining the engine start determination torque MTst in this manner, it is possible to suppress a drop in driving force that may occur when the engine is started.

In step S80, the ECU calculates the actual maximum motor torque MTmax. FIG. 7 is a flowchart that explains the details of the process (step S80) for calculating the actual maximum motor torque MTmax. As shown in FIG. 7, in step S80, the ECU executes the processes of steps S81 to S84.

In step S81, it is confirmed whether the engine start process is in progress. If the engine start process is in progress (step S81; YES), the process proceeds to step S82. If the engine start process is not in progress (step S81; NO), the process proceeds to step S84.

In step S82, it is confirmed whether or not the maximum motor torque MTmax can be temporarily increased. If the maximum motor torque MTmax can be temporarily increased (step S82; YES), the process proceeds to step S83. If the maximum motor torque MTmax cannot be temporarily increased (step S82; NO), the process proceeds to step S84.

In step S83, the motor torque obtained by adding the temporary up torque MTup to the basic maximum motor torque MTb is calculated as the actual maximum motor torque MTmax (the actual maximum motor torque MTmax that has been temporarily increased). On the other hand, in step S84, the basic maximum motor torque MTb is calculated as the actual maximum motor torque MTmax (the actual maximum motor torque MTmax that has not been temporarily increased).

By using the above flow of steps S10 to S80, it is possible to determine whether or not the maximum motor torque MTmax can be temporarily increased before cranking the engine 1, and to set an appropriate maximum motor torque MTmax during cranking depending on the condition of the hybrid vehicle 100.

Furthermore, when the required torque to be output to the drive shaft 4a based on the accelerator opening and vehicle speed becomes equal to or greater than the engine start determination torque MTst, the ECU determines whether to start the engine 1, and the vehicle transitions to HEV driving, with the first clutch K0 engaged and the rotating electric machine 2 included in the driving force source.

As described above, the control method for a hybrid vehicle according to this embodiment is a control method for a hybrid vehicle equipped with an engine 1 and a rotating electric machine 2, and includes the steps of: calculating a basic maximum motor torque MTb determined by the rotation speed of the rotating electric machine 2 and the input voltage of an inverter that drives the rotating electric machine 2; calculating a temporary up torque MTup that can temporarily increase the maximum motor torque MTmax of the rotating electric machine 2 before cranking the engine 1; setting the motor torque obtained by adding the temporary up torque MTup to the basic maximum motor torque MTb as the maximum motor torque MTmax1 during cranking of the engine 1; and calculating an engine start determination torque MTst used for engine 1 start determination based on the set maximum motor torque MTmax1 during cranking.

According to this embodiment, the maximum motor torque MTmax is temporarily increased during cranking, and the engine start determination torque MTst is determined based on this temporarily increased maximum motor torque MTmax. Therefore, the start of the engine 1 can be delayed compared to when the engine start determination torque MTst is determined without temporarily increasing the maximum motor torque MTmax. Therefore, it is possible to expand the EV driving range in which the engine 1 is stopped.

In addition, the hybrid vehicle control method according to this embodiment includes, before the step of calculating the temporary up torque MTup, a step of determining whether or not the maximum motor torque MTmax can be temporarily increased for target components that may become overheated due to cranking of the engine 1 by comparing the estimated temperature of the target components during cranking of the engine 1 with a preset upper limit temperature of the target components, and if the estimated temperature exceeds the upper limit temperature, it is determined that the maximum motor torque cannot be temporarily increased and the basic maximum motor torque is set to the maximum motor torque MTmax1 during engine cranking, and the engine start determination torque MTst is calculated based on the set maximum motor torque MTmax1 during cranking.

According to this embodiment, the setting of the maximum motor torque MTmax is determined based on the predicted temperature of the target components during cranking, which makes it possible to suppress damage to the components that may occur due to overheating and to appropriately protect the components.

The present invention is not limited to the above embodiment, and can be modified as appropriate without departing from the spirit of the present invention. For example, the above embodiment has been described with reference to an example in which the second clutch WSC is provided on the input shaft 3a of the transmission 3, but the present invention is not limited to this. As shown in FIG. 8, the hybrid vehicle 100 may have a configuration in which the second clutch WSC is omitted. FIG. 8 is a configuration diagram showing another configuration of a hybrid vehicle. In the case of the hybrid vehicle 100 shown in FIG. 8, it is possible to selectively switch between EV driving and HEV driving.

Reference Signs List 1 Engine 1a Crankshaft 2 Rotating electric machine 2a Rotating shaft 3 Transmission 3a Input shaft 3b Output shaft 4 Drive wheels 4a Drive shaft 100 Hybrid vehicle K0 First clutch MTb Basic maximum motor torque MTcr Cranking torque MTmar Margin torque MTmax Maximum motor torque MTst Engine start determination torque Mtup Temporary up torque WSC Second clutch

Claims (1)

A control method for a hybrid vehicle having an engine and a rotating electric machine, comprising:
calculating a basic maximum motor torque determined by a rotation speed of the rotating electric machine and an input voltage of an inverter that drives the rotating electric machine;
calculating a temporary increase torque capable of temporarily increasing a maximum motor torque of the rotary electric machine before cranking of the engine;
setting a motor torque obtained by adding the temporary increase torque to the basic maximum motor torque as a maximum motor torque during cranking of the engine;
calculating an engine start determination torque used for determining whether the engine is started, based on the set maximum motor torque during cranking;
having
Before the step of calculating the temporary increase torque,
a step of determining whether or not the maximum motor torque can be temporarily increased by comparing an estimated temperature of a target component that may be overheated due to cranking of the engine with a preset upper limit temperature of the target component during cranking of the engine;
a step of determining that the maximum motor torque cannot be temporarily increased when the estimated temperature exceeds the upper limit temperature, and setting the basic maximum motor torque to a maximum motor torque during cranking of the engine;
calculating an engine start determination torque based on the set maximum motor torque during cranking;
A method for controlling a hybrid vehicle.