JP2018100013A - Hybrid vehicle - Google Patents

Abstract

At least one embodiment of the present invention delays the voltage value of a driving battery from dropping to an engine starting voltage during traveling in an electric traveling mode when an EV priority switch is turned on in a hybrid vehicle. The purpose is to delay the timing from EV travel to engine start. An electric travel mode cancel control unit 43 that cancels the electric travel mode and drives the engine cancels switching from the electric travel mode to the hybrid travel mode when the voltage of the driving battery drops below a first predetermined value. Unit 51 and a release delay unit 53 that delays the reduction to the first predetermined value when the voltage of the driving battery drops to a second predetermined value higher than the first predetermined value. When the voltage of the driving battery decreases to the second predetermined value, the voltage value of the driving battery is delayed by suppressing the current value to the predetermined current value. [Selection] Figure 3

Description

  The present disclosure relates to a hybrid vehicle, and more particularly to switching control between an electric travel mode and a hybrid travel mode.

A hybrid vehicle including an internal combustion engine (engine) and an electric motor (motor) as a driving source for traveling is attracting attention as an environment-friendly vehicle.
In a hybrid vehicle, in order to reduce fuel consumption of the engine and from the viewpoint of quietness, it is desirable to suppress driving by engine driving and give priority to motor driving by electric power supplied from a driving battery as much as possible.

Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2009-143563) is provided with an EV priority switch so that a user can request switching between the EV priority mode and the HV (hybrid) mode. It is disclosed that “priority” in the EV priority mode basically means that the engine is stopped and the vehicle is driven using only the motor generator without maintaining the SOC of the power storage device at a predetermined target value. (Paragraph 0047 of Patent Document 1).
When the switch to the HV mode is requested by the travel mode switching request switch in the EV priority mode, when the SOC of the power storage device is lower than the threshold value Sth1, the travel mode is switched to the HV mode and the HV mode The SOC is controlled in the vicinity of the SOC at the time of the request for switching to, and when the SOC is equal to or greater than the threshold value Sth1, the EV priority mode is maintained. Further, it is shown that when the SOC reaches a threshold value Sth2 smaller than the threshold value Sth1, the running mode is forcibly switched to the HV mode.

  Patent Document 2 (Japanese Patent Laid-Open No. 2013-154652) discloses a first traveling mode that uses only power generated by an electric motor driven by electric power from a driving battery, power generated by the electric motor, and internal combustion engine. In a hybrid vehicle that travels in any one of the second travel modes using the generated power, when the charge rate of the drive battery is equal to or lower than the first threshold, the second travel mode is changed from the first travel mode to the second travel mode. Switching to a running mode is disclosed. Furthermore, it is shown that the first threshold value is set to increase as the degree of deterioration of the driving battery increases.

JP 2009-143563 A JP2013-154652A

As described above, Patent Document 1 and Patent Document 2 disclose switching to a hybrid travel mode that uses engine power when the SOC (State of Charge) of the drive battery drops below a predetermined value. .
However, there is no disclosure about delaying the switching timing from EV traveling by an electric motor to hybrid traveling using engine power. In particular, when the voltage of the driving battery is reduced to a predetermined value or less and the EV priority mode is switched to the hybrid driving by the engine driving, the control for delaying the reduction to the predetermined value as much as possible is disclosed. It has not been.

  Further, as one of the conditions for starting the engine during traveling in the EV priority mode, the voltage of the driving battery is reduced to a predetermined value or less. This voltage drop of the driving battery cannot be recognized by the driver and causes the engine to start unexpectedly. For this reason, it is desirable to suppress the unexpected engine start by delaying the decrease to the predetermined voltage as much as possible.

  Accordingly, in view of the above technical problem, in at least one embodiment of the present invention, in the hybrid vehicle, the voltage value of the driving battery is changed to the engine start voltage while the EV priority switch is turned on and the vehicle is traveling in the electric travel mode. The object is to delay the decrease and delay the timing from EV traveling to engine start, to reduce the fuel consumption of the engine by the EV traveling and to keep quietness.

(1) A hybrid vehicle according to at least one embodiment of the present invention travels by using an electric travel mode in which an electric motor is driven only by electric power from a driving battery, an engine power, and a power generated by the electric motor. In a hybrid vehicle comprising a hybrid travel mode,
When the EV priority switch requesting to prioritize the electric driving mode and the EV priority switch are turned ON and the electric driving mode is prioritized, the electric driving mode is canceled and the hybrid driving mode is set. An electric travel mode cancellation control unit that switches and drives the engine, and the electric travel mode cancellation control unit is configured to switch from the electric travel mode to the hybrid when the voltage of the driving battery decreases to a first predetermined value or less. A release unit that switches to a running mode; and a release delay unit that delays the reduction to the first predetermined value when the voltage of the driving battery drops to a second predetermined value that is higher than the first predetermined value; The release delay unit suppresses the current value to a predetermined current value when the voltage of the driving battery decreases to the second predetermined value, thereby Characterized by being configured to delay the pressure drop.

According to the above configuration (1), the EV priority switch is turned ON, and the voltage of the driving battery decreases while traveling in the electric travel mode, reaches the first predetermined value, and switches to the hybrid travel mode. When the voltage of the driving battery is reduced to a second predetermined value higher than the first predetermined value before starting the operation, the reduction to the first predetermined value is delayed, so that traveling in the electric driving mode is performed. It can be made to continue as much as possible.
As a result, fuel consumption of the engine can be suppressed, and quietness due to electric travel can be maintained. Furthermore, the frequency at which the engine is unexpectedly started without being recognized by the driver can be reduced.

(2) In some embodiments, in the configuration (1), the second predetermined value is changed according to a rate of change of battery temperature with respect to time.
According to the configuration (2), since the second predetermined value is changed according to the rate of change of the battery temperature with respect to time, battery deterioration due to an increase in the battery temperature is prevented, and it is effective for protecting the driving battery. .
The rate of change ΔT with respect to time of the battery temperature is calculated by ΔT = (current battery temperature−battery temperature at the start of electric running when the EV priority switch is turned on) / electric running duration from when the EV priority switch is turned on. Is done.

(3) In some embodiments, in the configuration (2), the second predetermined value is changed to a higher voltage value as the rate of change in temperature rises.
According to the configuration (3), the higher the rate of change in temperature, the faster the temperature rises. Therefore, from the viewpoint of battery protection, current suppression control can be performed earlier to suppress deterioration of the driving battery.

(4) In some embodiments, in any one of the configurations (1) to (3), the predetermined current value is changed according to a maximum battery temperature.
According to the configuration (4), since the maximum temperature of the battery affects the deterioration of the battery, the battery deterioration protection is controlled by controlling the predetermined current value, that is, the maximum current value to be suppressed, according to the maximum temperature. It is effective.

(5) In some embodiments, in the configuration (4), the predetermined current value is decreased as the maximum battery temperature increases.
According to the configuration (5), the suppression current value is lowered as the maximum battery temperature increases, which is effective for protection against deterioration of the driving battery.

(6) In some embodiments, in the configuration (2) or (3), the rate of change of the battery temperature with respect to time is the rate of change with respect to time in the battery cell that shows the highest temperature among the plurality of battery cells. It is characterized by being.
According to the configuration (6), since it is based on the detection data of the hottest battery cell among the plurality of battery cells, the deterioration protection of the battery (each battery cell) is reliably performed.

(7) In some embodiments, in the above configuration (4) or (5), the maximum temperature of the battery temperature is the maximum temperature of the battery cell indicating the highest temperature among the plurality of battery cells. And
According to the configuration (7), since it is based on the detection data of the hottest battery cell among the plurality of battery cells, the deterioration protection of the battery (each battery cell) is reliably performed.

  According to at least one embodiment of the present invention, in the hybrid vehicle, while the EV priority switch is turned on and traveling in the electric travel mode, the voltage value of the driving battery is delayed from dropping to the engine starting voltage, By delaying the timing from EV travel to engine start, it is possible to reduce engine fuel consumption and maintain quietness by EV travel.

1 is an overall schematic diagram of a hybrid vehicle according to an embodiment of the present invention. It is explanatory drawing of the driving mode of a hybrid vehicle. 1 is a schematic configuration diagram of a control device for a hybrid vehicle according to an embodiment of the present invention. It is a control flowchart by the control apparatus of the hybrid vehicle which concerns on one Embodiment of this invention. It is a time chart which shows the state of control by the control apparatus of the hybrid vehicle which concerns on one Embodiment of this invention, (A) Accelerator opening degree, (B) Vehicle speed, (C) Battery output, (D) Battery voltage, (E ) Battery current, (F) maximum cell temperature, (G) engine output, and (H) vehicle output.

Several embodiments of the present invention will be described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in these embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Only.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained. On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of other constituent elements.

A hybrid vehicle control apparatus according to an embodiment of the present invention will be described with reference to FIG.
FIG. 1 shows a schematic configuration of the hybrid vehicle 1. Although FIG. 1 shows a vehicle in which motors (electric motors) 3 are arranged on the front side and the rear side, the present invention is not limited to this.

As shown in FIG. 1, the hybrid vehicle 1 includes a power source 7 including an engine 5 and a motor 3 (front motor 3A, rear motor 3B), a fuel tank 9 for storing fuel to be supplied to the engine 5, and an engine 5 A generator (generator) 11 driven by the motor 11 and a motor 3 (3A, 3B), a driving battery (battery) 13 to which power generated by the generator 11 is supplied, and an engine 5 or motor 3 (3A, 3B) driving wheels 15 (front wheels 15A, rear wheels 15B) driven by the power generated by the power and a transaxle (power transmission) that transmits the power generated by the engine 5 or the motor 3 to the traveling wheels 15. Device) 17 (front transaxle 17A, rear transaxle 17B).
The engine 5 is disposed in front of the vehicle body, and the driving battery 13 is disposed under the floor at the center of the vehicle body.

  The hybrid vehicle 1 according to the embodiment of the present invention includes a front motor ECU (Electronic Control Unit) 19 for controlling the front motor 3A and the generator 11, a rear motor ECU 21 for controlling the rear motor 3B, and an engine ECU 23 for controlling the engine 5. The battery ECU 25 for controlling the driving battery 13 is provided, and the front motor ECU 19, the rear motor ECU 21, the engine ECU 23, and the integrated ECU 27 for controlling the battery ECU 25 are further provided. These ECUs are connected by in-vehicle CAN (Controller Area Network) communication.

  Further, the hybrid vehicle 1 according to the present embodiment has, as a travel mode, an EV travel mode (electric travel mode), a series travel mode (hybrid travel mode 1), or a parallel travel mode (hybrid travel mode 2). Any one of the travel modes can be arbitrarily selected, and the vehicle is configured to travel in any one mode.

  The EV travel mode is a travel mode in which the motor 3 (3A, 3B) is driven by the electric power charged in the drive battery 13, as shown in FIG. Electric power is supplied from the driving battery 13 to the motor 3 (3A, 3B). As a result, the engine 5 is stopped and the traveling wheels 15 (front wheels 15A, rear wheels 15B) are driven using only the motor 3 (3A, 3B) as a power source (referred to as “EV traveling”).

  The series travel mode is a travel mode in which the generator 11 is driven by the engine 5 and the motor 3 (3A, 3B) is driven by the electric power generated by the generator 11, as shown in FIG. Electric power generated by the generator 11 driven by the engine 5 is supplied to the motor 3 (3A, 3B) and the driving battery 13. The engine 5 is thus operated, but the traveling wheels 15 (15A, 15B) are driven using the motor 3 (3A, 3B) as a power source (hybrid traveling mode 1).

As shown in FIG. 2C, the parallel traveling mode is a traveling mode in which the engine 5 and the motor 3 (3A, 3B) are power sources for traveling. The engine 5 and the front motor 3A drive the front wheels 15A, and the rear motor 3B drives the rear wheels 15B (hybrid travel mode 2).
Further, surplus power may be supplied from the generator 11 driven by the engine 5 to the driving battery 13.

  Further, the front transaxle 17A is provided with a clutch device 29, and connection and disconnection are controlled in accordance with switching between the series travel mode and the parallel travel mode. In the parallel travel mode, the clutch device 29 is connected. The rotation of the output shaft of the engine 5 is transmitted to the front wheel 15A. In the series travel mode, the clutch device 29 is disconnected and the rotation of the output shaft of the engine 5 is not transmitted to the front wheels 15A.

As described above, the battery ECU 25 is provided for the drive battery 13 to detect the temperature, output voltage, discharge current, and state of charge (SOC) of the drive battery 13 and detect them. Information is transmitted to the integrated ECU 27.
The battery ECU 25 is provided with a cell ECU 28 that detects the state of each cell constituting the battery. The cell ECU 28 acquires temperature information from the temperature sensor 30 provided in each cell.

  For the engine 5, an engine ECU 23 is provided, which detects various information such as the amount of fuel supplied to the combustion chamber and the supply timing representing the operating state of the engine, and transmits the detected information to the integrated ECU 27. The ECU 23 controls the amount of fuel supplied to the combustion chamber of the engine 5 and the supply timing in accordance with an instruction from the integrated ECU 27.

  A front motor ECU 19 is provided for the front motor 3A, and a rear motor ECU 21 is provided for the rear motor 3B. Torque information of each of the front motor 3A and the rear motor 3B is detected, and the detected information is transmitted to the integrated ECU 27. The front motor ECU 19 and the rear motor ECU 21 each of the front motor 3A and the rear motor 3B according to instructions from the integrated ECU 27. In order to control the output torque of the motor, inverter control of each motor is executed.

Next, the integrated ECU (control device) 27 will be described.
As shown in FIGS. 1 and 2, the integrated ECU 27 includes a signal input unit, a signal output unit, a storage unit, a calculation unit, and the like (not shown). A signal from the EV priority switch 31 is input to the signal input unit. The EV priority switch 31 is a switch operated by the driver in order to request that the EV traveling is prioritized as much as possible, that is, until a predetermined condition is satisfied.
The predetermined condition for canceling EV traveling is, for example, when the accelerator depression amount is a certain value or more, or when the SOC of the driving battery 13 is lowered to a certain value or less, the voltage value of the driving battery 13 is a certain value or less. It is various when it falls. In the present embodiment, the EV traveling is canceled when the voltage value of the driving battery 13 drops below a certain level.

  In addition, signals from a vehicle state detection sensor mounted on the vehicle, for example, a vehicle speed sensor 33, an accelerator opening sensor 35, and the like are input to the input signal unit.

  As shown in FIG. 3, the integrated ECU 27 mainly includes an EV travel mode release control unit 43, an EV travel mode control unit 45, a series travel mode control unit 47, and a parallel travel mode control unit 49.

  The EV travel mode control unit 45 further includes signals from various sensors in the vehicle operating state, information on the current, voltage, SOC, etc. of the driving battery 13 from the battery ECU 25, information such as torque from the front motor ECU 19 and the rear motor ECU 21, The engine 5 is stopped based on the engine state information from the engine ECU 23, and the engine 15 is driven so as to drive the traveling wheels 15 (front wheels 15A, rear wheels 15B) using only the motor 3 (3A, 3B) as a power source. The ECU 23, the front motor ECU 19, and the rear motor ECU 21 are instructed.

  The series travel mode control unit 47 includes signals from various sensors in the vehicle driving state, information on the current, voltage, SOC, etc. of the driving battery 13 from the battery ECU 25, information such as torque from the front motor ECU 19 and the rear motor ECU 21, Based on the engine state information from the engine ECU 23, the electric power generated by the generator 11 driven by the engine 5 is supplied to the motor 3 (3A, 3B) and the driving battery 13, and the motor 3 (3A, The engine ECU 23, the front motor ECU 19, and the rear motor ECU 21 are instructed to drive the traveling wheels 15 (15A, 15B) using 3B) as a power source.

  The parallel running mode control unit 49 is configured to output signals from various sensors in the vehicle operating state, information on the current, voltage, SOC, etc. of the driving battery 13 from the battery ECU 25, information on torque, etc. from the front motor ECU 19 and the rear motor ECU 21, The driving wheels 15 (15A, 15B) are driven by the engine 5 and the motors 3 (3A, 3B) on the basis of the information on the engine state from the engine ECU 23, and the driving battery is driven from the generator 11 driven by the engine 5. The engine ECU 23, the front motor ECU 19, and the rear motor ECU 21 are instructed to supply surplus power to 13.

  The EV travel mode cancel control unit 43 cancels the EV travel mode and switches to the series travel mode (hybrid travel mode 1) or the parallel travel mode (hybrid travel mode 2) to control the driving of the engine 5.

  When the EV priority switch 31 is ON, the EV travel mode release control unit 43 reaches a predetermined voltage value V1 (first predetermined value) and decreases to a voltage lower than the voltage during the travel in the EV travel mode. Sometimes, the voltage of the release unit 51 that drives the engine 5 by switching to the series travel mode (hybrid travel mode 1) or the parallel travel mode (hybrid travel mode 2) and the driving battery 13 is higher than the predetermined voltage value V1. And a release delay unit 53 that delays the decrease to the predetermined voltage value V1 when the voltage decreases to the predetermined voltage value V2 (second predetermined value).

  In addition, the release delay unit 53 achieves this by suppressing the discharge current value output from the drive battery 13 to a predetermined constant current value lower than normal in order to delay the voltage drop of the drive battery 13. ing. As shown in FIG. 5E, the voltage is suppressed to a predetermined current value Im so that the voltage drop is delayed as shown in FIG. That is, normally, the current value that rises to maintain the output is lowered to a predetermined current value Im, thereby causing a voltage increase due to the internal resistance of the driving battery 13 and the current decrease, and further, the current consumption is reduced. The voltage drop can be delayed by being small. The predetermined current value Im means a maximum current value to be suppressed.

The integrated ECU 27 automatically selects a travel mode so that energy efficiency is high. For example, when the vehicle is traveling at a low or medium speed such as in a residential area or in a town, the EV traveling mode control unit 45 controls the driving in the EV traveling mode that travels with the electric power of the driving battery 13.
The integrated ECU 27 is one of the start conditions of the engine 5 when the accelerator is depressed or the accelerator depression amount is constant when acceleration is required or when the vehicle is traveling at a high speed during the EV traveling mode. On the basis of the decrease in the output voltage of the driving battery 13, the EV running mode release control unit 43 automatically starts the engine 5 and supplies power to the front motor 3 </ b> A, the rear motor 3 </ b> B, and the driving battery 13. The operation is switched to the series driving mode (hybrid driving mode 1) to be supplied. Further, during higher load and higher speed driving, the EV driving mode release control unit 43 automatically starts the engine 5 and uses the driving force of the engine 5 to drive, and the front motor 3A and the rear motor 3B assist. Then, the operation is switched to the parallel driving mode (hybrid driving mode 2). In the case of this parallel travel mode, the drive battery 13 may be charged.
Further, the integrated ECU 27 uses the front motor 3A and the rear motor 3B as generators during deceleration, regenerates deceleration energy, and charges the drive battery 13.

Next, the control of the EV travel mode release control unit 43 will be described with reference to the control flowchart of FIG. 4 and the control time chart of FIG.
In the flowchart of FIG. 4, first, in step S1, it is determined whether or not the EV priority mode is in effect. That is, it is determined whether or not the EV priority switch 31 is turned on by the driver's intention and the vehicle is in the EV traveling mode.

  In the case of No, the process is returned, and in the case of Yes, the process proceeds to Step S2 to update the battery temperature ΔT. That is, based on the information on the cell temperature from the cell ECU 28, the rate of change ΔT with respect to time is calculated from the temperature information of the battery cell that is at the highest temperature, and ΔT is updated every calculation cycle. The calculation of ΔT is calculated by: ΔT = (current battery cell temperature−battery temperature at the start of electric travel when the EV priority switch is turned on) / electric travel duration time from when the EV priority switch is turned on.

Next, it progresses to step S3 and the predetermined voltage value V2 (2nd predetermined value) is updated according to (DELTA) T.
The predetermined voltage value V2 is updated to a higher predetermined voltage value V2 as ΔT increases, that is, as the rate of change in temperature rises. The predetermined voltage value V2 is higher than the engine starting voltage V1, and does not become lower than the engine starting voltage V1.
For this reason, since the higher the rate of change of temperature rise, the higher the temperature is reached earlier. From the viewpoint of battery protection, the predetermined voltage value V2 is made higher and current suppression control is performed earlier to suppress deterioration of the driving battery. Can be.

In step S4, it is determined whether or not the battery voltage of the driving battery 13 is equal to or lower than the updated predetermined voltage value V2. If no, the process returns to step S2, and if yes, the process proceeds to step S5.
In step S5, based on the information of each cell temperature from the cell ECU 28, the maximum temperature is detected from the temperature information of the battery cell having the highest temperature. In step S6, a predetermined current value Im is determined according to the maximum temperature.
The predetermined current value Im is updated so as to decrease as the maximum battery temperature increases. As described above, the predetermined current value Im, which is the suppression current value, is lowered as the maximum battery temperature increases, which is effective for protection of the deterioration of the driving battery.

In step S7, the current is suppressed by changing to the determined predetermined current value Im. In step S8, it is determined whether or not an engine start condition is satisfied. That is, it is determined whether or not the battery voltage has dropped below a predetermined voltage value V1 (first predetermined value). If it falls, it will become Yes and will progress to step S9, will switch to series driving mode (hybrid driving mode 1) or parallel driving mode (hybrid driving mode 2) mode, and engine 5 will be started.
On the other hand, if the battery voltage has not decreased to the predetermined voltage value V1 in step S8, the process returns to step S5, and steps S5 to S8 are repeated.

Next, a control time chart will be described with reference to FIG.
5A is the accelerator opening, (B) is the vehicle speed, (C) is the battery output, (D) is the battery voltage, (E) is the battery current, (F) is the maximum cell temperature, and (G) is Engine output, (H) indicates vehicle output.

As shown in FIG. 5 (A), the accelerator opening degree is increased by depressing the accelerator (accelerator pedal) at time t0 to t1 during the EV traveling mode (in the EV priority mode) when the EV priority switch 31 is turned on, and thereafter Is shown in a constant state.
As shown in FIG. 5 (B), the vehicle speed is increased under the condition that the accelerator is stepped on and the accelerator is in a constant state.
As shown in FIG. 5 (C), the battery output of the driving battery 13 increases as the accelerator is stepped on, reaches the Q point at t1, and then passes to t2 in a state where the accelerator is constant and the output is constant.

  As shown in FIG. 5D, the voltage of the driving battery 13 decreases because the electric power is consumed by EV traveling, and reaches a predetermined voltage value V2 at t2. Current suppression starts at time t2 when the voltage drops to the predetermined voltage value V2. That is, as shown in FIG. 5E, the current is suppressed to a predetermined current value Im. As a result, as shown in FIG. 5D, the slope of the voltage decrease is made gentle so that the voltage drop is delayed. That is, by lowering to the predetermined current value Im, the voltage rise R due to the internal resistance and current drop of the driving battery 13 can be brought about, and furthermore, the voltage drop can be delayed due to the small current consumption. After the voltage rise R, the voltage decreases and reaches a predetermined voltage value V1, which is an engine start voltage value, and the engine is started.

  As shown in FIG. 5E, the current increases rapidly to t1 when the accelerator is depressed, and then increases to maintain the battery output until t2. Then, as described above, it decreases to the predetermined current value Im at t2, and the predetermined current value Im is kept constant.

  As shown in FIG. 5F, the maximum cell temperature increases as the current increases. Then, after the current value is suppressed at t2, the temperature rises gently and increases due to the current suppression. The maximum cell temperature indicates a cell temperature in the highest temperature state among a plurality of cells. Based on this maximum cell temperature, the rate of change ΔT with respect to time is calculated.

As shown in FIG. 5 (G), the output of the engine 5 is lowered to the predetermined voltage value V1 that is the engine starting voltage value because the EV priority switch 31 is ON and the EV running mode is in the driver's intention. Until this occurs, the engine 5 is in a stopped state.
As shown in FIG. 5 (H), the vehicle output is based only on the output from the drive battery 13 until the engine is started at t3 because the EV priority switch 31 is ON for the driver's intention and the vehicle is in the EV travel mode. It is a vehicle output and changes according to the same tendency as the battery output in (C).

According to the present embodiment described above, the EV priority switch 31 is turned ON, and the voltage of the driving battery 13 decreases while traveling in the EV traveling mode, and reaches the predetermined voltage value V1 to switch to the hybrid traveling mode. Before starting the engine, when the voltage of the driving battery 13 decreases to a predetermined voltage value V2 higher than the predetermined voltage value V1, the current (output) is suppressed and the decrease to the predetermined voltage value V1 is delayed. The driving in the EV driving mode desired by the driver can be continued as much as possible.
As a result, fuel consumption of the engine can be suppressed, and quietness due to electric travel can be maintained. Furthermore, the frequency at which the engine is unexpectedly started without being recognized by the driver can be reduced.

  Further, since the predetermined voltage value V2 that is the determination threshold value of the voltage of the driving battery 13 is changed according to the rate of change ΔT with respect to time of the battery temperature, in particular, the voltage value increases as the rate of change ΔT of the temperature rise increases. Therefore, the EV driving mode can be continued as much as possible, and from the viewpoint of battery protection, current can be suppressed early to prevent deterioration of the driving battery.

  Further, since the predetermined current value Im that decreases to the predetermined voltage value V2 and suppresses the current value is changed according to the maximum temperature of the battery (battery cell), in particular, the maximum temperature of the battery (battery cell) increases. Therefore, by controlling the current suppression value according to the maximum temperature that affects the deterioration of the battery, it is effective for protecting the deterioration of the battery.

  Further, according to the present embodiment, the rate of change ΔT with respect to time of the battery temperature, and the maximum temperature of the battery cell temperature is the rate of change ΔT in the battery cell showing the highest temperature among the plurality of battery cells, and the maximum temperature. Therefore, the deterioration protection of each battery cell can be reliably performed.

  According to at least one embodiment of the present invention, when the EV priority switch is turned on and the vehicle is traveling in the EV traveling mode, the voltage value of the driving battery is delayed from dropping to the engine starting voltage, and the EV traveling to the engine By delaying the timing to start and associating the drive battery temperature with the output suppression during EV traveling, the fuel consumption of the engine can be reduced and the quietness can be maintained. Suitable for use.

1 Hybrid vehicle 3 Motor (electric motor)
3A Front motor 3B Rear motor 5 Engine 13 Drive battery (battery)
19 Front motor ECU
21 Rear motor ECU
23 Engine ECU
25 Battery ECU
27 Integrated ECU
28 Cell ECU
30 temperature sensor 31 EV priority switch 33 vehicle speed sensor 35 accelerator opening sensor 43 EV travel mode release control unit 45 EV travel mode control unit 47 series travel mode control unit 49 parallel travel mode control unit 51 release unit 53 release delay unit

Claims (7)

In a hybrid vehicle comprising: an electric travel mode that travels by driving an electric motor only with electric power from a drive battery; and a hybrid travel mode that travels using engine power and power generated by the electric motor.
An EV priority switch that requests to prioritize the electric driving mode;
An electric travel mode release control unit that cancels the electric travel mode and switches to the hybrid travel mode to drive the engine when the EV priority switch is turned on and the electric travel mode is prioritized; The electric travel mode release control unit comprises
A release unit that switches from the electric travel mode to the hybrid travel mode when the voltage of the driving battery drops below a first predetermined value;
A release delay unit that delays the decrease to the first predetermined value when the voltage of the driving battery decreases to a second predetermined value higher than the first predetermined value;
The release delay unit is configured to delay the voltage drop of the driving battery by suppressing the current value to a predetermined current value when the voltage of the driving battery drops to the second predetermined value. A featured hybrid vehicle.   The hybrid vehicle according to claim 1, wherein the second predetermined value is changed according to a rate of change of battery temperature with respect to time.   The hybrid vehicle according to claim 2, wherein the second predetermined value is changed to a higher voltage value as the rate of change in temperature increase increases.   The hybrid vehicle according to any one of claims 1 to 3, wherein the predetermined current value is changed in accordance with a maximum battery temperature.   The hybrid vehicle according to claim 4, wherein the predetermined current value decreases as the maximum battery temperature increases.   4. The hybrid vehicle according to claim 2, wherein the rate of change of the battery temperature with respect to time is a rate of change with respect to time in a battery cell that exhibits the highest temperature among a plurality of battery cells.   6. The hybrid vehicle according to claim 4, wherein the maximum temperature of the battery temperature is a maximum temperature of a battery cell exhibiting a highest temperature among a plurality of battery cells.

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