JP2019156102A - Hybrid vehicle drive control system - Google Patents

Abstract

To provide a hybrid vehicle which can travel using an electric motor as much as possible.SOLUTION: A hybrid vehicle drive control system comprises: an electric motor 4 and an engine 3 for a vehicle drive source; a battery 5; charging rate detection means 24; travel mode selection means 10A which selects any of a motor travel mode for traveling using the electric motor 4, a hybrid travel mode for traveling using the electric motor 4 and the engine 3, and an engine travel mode for traveling using the engine 3, based on a driving state of the vehicle and the charging rate, and which selects the engine travel mode when at least, the charging rate becomes less than a charging rate lower limit value; and priority mode selection means 23 capable of setting a motor travel priority mode. The travel mode selection means switches the charging rate lower limit from a normal value to a motor travel priority value lower than the normal value and selects the travel mode, when the motor travel priority mode is selected.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hybrid vehicle drive control system suitable for use in a plug-in hybrid.

  The hybrid vehicle includes an electric motor and an engine (internal combustion engine) as a drive source, and a hybrid that travels using both the motor travel mode (EV travel mode) that travels using only the electric motor and the electric motor and engine. There are a travel mode (HEV travel mode) and an engine travel mode in which the vehicle travels using only the engine. These modes are selected mainly according to the driving state of the vehicle defined by the required torque to the drive source and the vehicle speed, and the state of charge (SOC) of the battery for the power source of the electric motor.

  In general, the motor travel mode is selected when the required torque and the vehicle speed are relatively low, and the hybrid travel mode is selected when the required torque and the vehicle speed increase. However, since the battery deteriorates when the charging rate decreases excessively, a lower limit value of the SOC that permits the use of the battery is set, and if the SOC decreases below the lower limit value, engine startability is secured and the battery is protected. Therefore, an engine running mode that does not use an electric motor is selected.

  As described above, if the SOC is not less than the lower limit value, the HEV driving mode is selected when the required torque or the vehicle speed increases. However, in the hybrid vehicle, from the viewpoint of reducing exhaust gas, improving fuel consumption, and reducing driving noise. I want to be able to select an EV driving mode that uses the engine as little as possible. In this regard, Patent Document 1 describes a technique for preferentially selecting an EV traveling mode while suppressing a required torque during acceleration during active cruise control.

JP 2017-114290 A

  By the way, as described above, in a hybrid vehicle, it is desirable to reduce the frequency of use of the engine by using an electric motor as much as possible. In particular, users of plug-in hybrid vehicles (PHEV) are increasingly demanding to use EV travel as much as possible without using the engine as much as possible.

  These users regard the engine running as a “disappointment” as a more “disappointing feeling” and drive by suppressing the accelerator operation or using the heater to prevent the engine from starting as much as possible when driving in the EV driving mode. It is devised so that the required torque to the power source is suppressed and switching to the HEV traveling mode is not performed.

  However, if the SOC becomes less than the lower limit value, the engine must be used even if the required torque is reduced, so that a user who wants to use EV driving as much as possible is given a "disappointment". become.

  The present invention has been made by paying attention to such a problem, and an object of the present invention is to provide a hybrid vehicle drive control system that enables a hybrid vehicle to travel using an electric motor as much as possible.

  (1) A hybrid vehicle drive control system according to the present case includes an electric motor and an engine provided as a vehicle drive source, a battery provided as a power source of the electric motor, and a charge rate detection for detecting a charge rate of the battery. Means, a motor travel mode in which the vehicle travels using only the electric motor based on the driving state of the vehicle and the charging rate, and the vehicle travels using both the electric motor and the engine. Driving in which a hybrid driving mode is selected and an engine driving mode in which only the engine is used are selected, and the engine driving mode is selected at least when the charging rate is less than a charging rate lower limit value. A drive control system for a hybrid vehicle comprising mode selection means, and a travel mode using the electric motor. Priority mode selection means capable of setting a motor driving priority mode for preferentially selecting the driving mode, and when the motor driving priority mode is selected, the driving mode selection means changes the charging rate lower limit value from the normal value to the normal value. The driving mode is selected by switching to a motor driving priority value lower than the value.

(2) It is preferable that a health level detection unit that detects the health level of the battery is further provided, and the motor travel priority value is variably set so as to increase as the health level decreases.
(3) Remaining capacity calculating means for calculating the remaining capacity of the battery based on the charging rate and the soundness level is further provided, and the running mode selecting means is configured to charge the battery when the remaining capacity becomes less than a capacity lower limit value. It is preferable to select the engine travel mode regardless of the rate.
(4) It further comprises temperature detection means for detecting the temperature of the battery, and the travel mode selection means is operated under other conditions (for example, the charging rate and the remaining capacity) when the battery is in a cold state where the temperature is lower than a reference temperature. Regardless of whether the engine travel mode is selected.
(5) It is preferable that the hybrid vehicle is a plug-in hybrid vehicle capable of charging the battery with an external power source.

  According to the hybrid vehicle drive control system of the present case, when the motor travel priority mode is selected, the charge mode lower limit value is switched from the normal value to the motor travel priority value lower than the normal value, so that the travel mode is selected. The driving mode using the electric motor is preferentially selected, and the driver's request can be answered.

1 is a schematic configuration diagram of a hybrid vehicle drive control system according to an embodiment. It is a graph which shows the capacity | capacitance deterioration characteristic (change with time of a full charge capacity) of a battery. It is a graph which shows the discharge characteristic (change of the battery voltage with respect to discharge capacity) of a battery. It is a conceptual diagram which shows the fluctuation characteristic of the charging rate and remaining capacity by deterioration of a battery.

Hereinafter, embodiments will be described with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment. Each configuration of the following embodiments can be implemented with various modifications without departing from the gist thereof, and can be selected or combined as appropriate.

[1. System configuration]
As shown in FIG. 1, the hybrid vehicle 1 includes a drive source 2 including an engine (internal combustion engine) 3 and an electric motor (hereinafter also simply referred to as a motor) 4, a generator 4G that generates electric power using the driving force of the engine 3, A driving battery (hereinafter also simply referred to as a battery) 5 that supplies electric power to the motor 4 and is charged by electric power generated by the generator 4G or electric power from an external power source such as a household power source; The engine 3 and the power transmission device 6 for transmitting the power generated by the motor 4 to the traveling wheels 7 are provided.

The hybrid vehicle 1 includes an engine ECU (Electronic Control Unit) 11 that controls the engine 3, a motor ECU 12 that controls the motor 4, a battery ECU 13 that controls the battery 5, and the engine ECU 11, the motor ECU 12, and the battery. And an integrated ECU 10 that controls the ECU 13. These ECUs are connected to each other so that information can be transmitted by in-vehicle CAN (Controller Area Network) communication or the like.
Moreover, the hybrid vehicle 1 is configured as a plug-in hybrid vehicle that can charge the battery 5 by an external power source 27 such as a household power source.

  The hybrid vehicle 1 uses both an EV travel mode (motor travel mode) in which the vehicle travels using only the driving force of the motor 4 and both the driving force of the motor 4 and the driving force of the engine 3 as travel modes. The vehicle has a HEV driving mode (hybrid driving mode) for driving the vehicle, and an engine driving mode for driving the vehicle using only the driving force of the engine 3, and one of these driving modes is selected and selected. The vehicle is configured to travel in the travel mode. The HEV traveling mode includes a traveling state in which the generator 4G is driven by the driving force of the engine 3 while traveling by the driving force of the motor 4.

  The integrated ECU 10 determines the EV travel mode based on the driving state of the vehicle, such as the required torque to the drive source 2 and the vehicle speed, and the state of charge (SOC) of the battery 5 when the vehicle travels (powering). And a travel mode selection unit (travel mode selection means) 10A that selects any one of the HEV travel mode and the engine travel mode. The charge rate (SOC) is defined as a value obtained by dividing the current charge amount by the full charge amount.

  The integrated ECU 10 receives detection information of the accelerator opening and the vehicle speed from an accelerator opening sensor 21 that detects the accelerator opening corresponding to the required torque to the drive source 2 and a vehicle speed sensor 22 that detects the vehicle speed. In addition, a charge rate detection unit (charge rate detection means) 24 for detecting (or calculating) the charge rate of the battery 5 is provided, and the integrated ECU 10 receives charge rate detection information (or calculation) from the charge rate detection unit 24. Information) is entered. The traveling mode selection unit 10A selects one of the traveling modes based on the input information.

  That is, in the driving mode selection unit 10A, when the charging rate is equal to or higher than the charging rate lower limit value, the EV driving mode is selected when the accelerator opening and the vehicle speed are low, and HEV is selected when the accelerator opening or the vehicle speed is high. Select the driving mode. On the other hand, when the charging rate falls below the lower limit of the charging rate, an engine running mode that does not use the motor 4 is selected in order to ensure startability of the engine 3 and protect the battery 5.

However, this system is provided with an EV priority switch (priority mode selection means) 23 capable of setting an EV priority mode for preferentially selecting an EV traveling mode, and an operation signal of the EV priority switch 23 is also input to the integrated ECU 10. Is done. When the EV priority switch 23 is turned on, the travel mode selection unit 10A sets the motor charge priority value (motor travel priority) that is lower than the normal value from the normal value (normal charge rate lower limit value). Switch to the charging rate lower limit value) and select the driving mode. Even if the EV priority switch 23 is turned on, the on operation is automatically reset to off after a predetermined time has elapsed.
In connection with this mode selection, the integrated ECU 10 further includes a health degree detection unit (health degree detection means) 25 that detects (or calculates) the health level (battery health level) of the battery 5 and the temperature of the battery 5 (battery). Detection signals are input from temperature detection units (temperature detection means) 26 that detect (or calculate) (temperature).

  The charging rate lower limit value is provided with a normal value (for example, 30%) and a motor driving priority value (for example, 20%) lower than this, and is normal unless the EV priority switch 23 is turned on. The travel mode is determined using the value, and if the EV priority switch 23 is turned on, the travel mode is determined using the motor travel priority value. Therefore, if the EV priority switch 23 is off, the engine running mode in which the motor 4 is not used is always selected when the charging rate is below the normal value. However, if the EV priority switch 23 is on, the charging rate is below the normal value. Even if it is equal to or greater than the motor travel priority value, the EV travel mode using only the motor 4 is selected.

  By the way, the reason why the lower limit value of the charging rate is conventionally set is to secure the startability of the engine 3 and to protect the battery 5, and if the lower limit value of the charging rate is lowered, the startability of the engine 3 is reduced. It is also considered that securing and protection of the battery 5 cannot be achieved. Regarding this point, the conventional charge rate lower limit value is set with a certain margin, and in this system, the motor driving priority value in which the charge rate lower limit value is lowered within the range of this margin is used. Since the time during which the ON operation of the EV priority switch 23 is valid is also limited, there is no problem in ensuring startability of the engine 3 and protecting the battery 5.

Here, the reason why the lower limit of the charging rate of the battery 5 is set with a certain margin will be described.
First, reference is made to FIG. 2 showing a general battery capacity deterioration characteristic. In FIG. 2, the horizontal axis indicates the battery charge / discharge time (charge / discharge cycle), and the vertical axis indicates the remaining capacity of the battery (corresponding to the state of health (SOH) described later), that is, The ratio of the full charge amount that decreases with the lapse of charge / discharge time when the full charge amount at the time of a new article is taken as 100% is taken. As shown in FIG. 2, the battery 5 has a characteristic that its capacity deteriorates as the charge / discharge time (charge / discharge cycle) increases.

Reference is now made to FIG. 3 showing the discharge characteristics of a typical battery. In FIG. 3, the horizontal axis represents the discharge capacity in one discharge cycle of the battery, and the vertical axis represents the battery voltage corresponding to the discharge capacity. In addition, the solid line indicates the characteristics when new, and the two-dot chain line indicates a case where deterioration due to use of the battery occurs. As shown in FIG. 3, in any case, even if the discharge proceeds, the voltage decreases slightly for a while, but the voltage rapidly decreases as the discharge further proceeds.
This characteristic is that when the battery is deteriorated, the discharge capacity at which the voltage at the time of discharge rapidly decreases is faster than when the battery is new.

  If the voltage is discharged to a point where the voltage suddenly drops, for example, it becomes difficult to generate a high voltage required when starting the engine, for example, and it greatly promotes deterioration of the battery. For this reason, it is necessary not to discharge the battery to a region where the voltage suddenly drops, that is, not to use the battery.

  Reference is now made to FIG. 4 showing the concept of fluctuation characteristics between the charge rate and the remaining capacity due to general battery deterioration. In FIG. 4, the charging rate and remaining capacity of the battery when new are shown on the left, and the charging rate and remaining capacity of the battery deteriorated due to use are shown on the right. Further, the height of each cylinder indicates the charging rate, and the volume of each cylinder indicates the remaining capacity. As shown in FIG. 4, it can be seen that as the battery deteriorates, the charging rate increases even with the same remaining capacity.

  As shown in FIG. 2, the value of the charge capacity (full charge capacity) when the charge rate is 100%, which is the remaining capacity of the battery (that is, the soundness level), decreases with the deterioration of the battery. Since the remaining capacity of the battery can be calculated by charging rate × soundness, if the value of soundness decreases due to deterioration, the charging rate is increased to ensure the same remaining capacity as when new.

  To start the engine 3, a certain amount of electric power is required. From this point of view, the engine 3 can be started without any trouble with a remaining capacity of 20% when it is new, but the engine 3 can be started when it is deteriorated unless it has a higher charge rate (for example, 30% shown in FIG. 4) than when it is new. It becomes impossible to start without trouble.

  Since the conventional battery charge rate lower limit value is uniformly used both when it is new and deteriorated, the battery charge rate lower limit value has a certain margin so that the engine 3 can be started without any problem even when it deteriorates. It is set with.

  In this system, the margin of the lower limit of the charging rate is used, but naturally, ensuring startability of the engine 3 when the battery is deteriorated is also taken into consideration. In other words, in this system, the lower the capacity remaining rate (health level) of the battery 5 is variably set so that the motor traveling priority value of the charging rate lower limit value increases. Therefore, the remaining capacity of the battery 5 is ensured even when the battery is deteriorated, and the startability of the engine 3 is ensured.

  In the present system, the integrated ECU 10 is provided with a remaining capacity calculation unit (remaining capacity calculation means) 10B that calculates the remaining capacity of the battery 5 based on the charging rate and the soundness level. When the remaining capacity falls below a preset capacity lower limit value, the engine running mode is selected regardless of the charging rate. Therefore, the remaining capacity of the battery 5 is more reliably ensured even when the battery is deteriorated, and the startability of the engine 3 is further ensured.

  Furthermore, in the present system, the traveling mode selection unit 10A selects the engine traveling mode when the battery 5 is cold when the temperature of the battery 5 is lower than a preset reference temperature (for example, −10 ° C.). That is, when the battery is cold, the reaction in the battery 5 becomes dull and it becomes difficult to generate a sufficient voltage. Therefore, traveling using the motor 4 places a heavy burden on the battery 5 and promotes deterioration of the battery 5. Therefore, an engine running mode that does not use the motor 4 is selected to protect the battery 5.

[Action and effect]
Since the hybrid vehicle drive control system according to the present embodiment is configured as described above, the following operations and effects can be obtained.
That is, in the present system, when the motor travel priority mode is selected, the travel mode is selected by switching the lower limit value of the charging rate from the normal value to the motor travel priority value lower than this, so the travel mode using the motor 4 is selected. This makes it possible to answer the demands of drivers who want to prioritize motor travel.

  Further, in this system, the motor driving priority value is variably set so as to increase as the battery soundness level decreases, that is, close to the normal value of the charging rate lower limit value. The remaining capacity of the battery 5 is secured and the startability of the engine 3 is secured. Further, deterioration of the battery 5 is also suppressed.

  Further, in the present system, when the remaining capacity becomes less than the preset capacity lower limit value, the HEV traveling mode or the engine traveling mode is selected regardless of the charging rate, so that the remaining capacity of the battery 5 is maintained even when the battery 5 is deteriorated. The startability of the engine 3 is further ensured more reliably. Moreover, deterioration suppression of the battery 5 is also promoted.

Further, in this system, when the battery 5 is in a cold state where the temperature of the battery 5 is lower than a preset reference temperature (for example, −10 ° C.), the engine running mode is selected, and thus a heavy burden is placed on the cold battery 5. Can be avoided, and deterioration of the battery 5 can be suppressed.
In particular, this hybrid vehicle is a plug-in hybrid vehicle that can charge the battery 5 with an external power source, and the driver has a strong tendency to prioritize motor driving. Contribute.

[Others]
Although the embodiment has been described above, the hybrid vehicle drive control system according to the present invention can be implemented by appropriately changing the embodiment.
For example, in the above-described embodiment, the hybrid vehicle drive control system is applied to a plug-in hybrid vehicle. However, the present system is not limited to a plug-in hybrid vehicle and can be widely applied to hybrid vehicles.

  In the above embodiment, the motor driving priority value is variably set so as to increase as the soundness level decreases. However, the motor driving priority value is set to a fixed value, the soundness level is below a certain level, or the battery usage time or usage When the cycle reaches a certain level or more, the use of the motor travel priority value may be prohibited to achieve engine startability and battery protection. In this case, when the remaining capacity becomes less than the capacity lower limit value, the control of selecting the engine running mode regardless of the charging rate can be omitted.

1 Hybrid vehicle 2 Power source 3 Engine (internal combustion engine)
4 Electric Motor 4G Generator 5 Battery for Driving 6 Power Transmission Device 7 Traveling Wheel 10 Integrated ECU
10A Travel mode selection unit (travel mode selection means)
10B Remaining capacity calculation unit (remaining capacity calculation means)
11 Engine ECU
12 Motor ECU
13 Battery ECU
21 Accelerator opening sensor 22 Vehicle speed sensor 23 EV priority switch (priority mode selection means)
24 charge rate detection unit (charge rate detection means)
25 Soundness detection unit (health detection means)
26 Temperature detection part (temperature detection means)

Claims (5)

An electric motor and an engine provided as a drive source of the vehicle;
A battery provided as a power source of the electric motor;
Charging rate detecting means for detecting the charging rate of the battery;
When the vehicle is traveling, based on the driving state of the vehicle and the charging rate, a motor travel mode that travels using only the electric motor, and a hybrid travel that travels using both the electric motor and the engine. Driving mode selection means for selecting the driving mode of the engine and the driving mode of the engine that uses only the engine and selecting the driving mode of the engine when at least the charging rate is less than the charging rate lower limit value. A drive control system for a hybrid vehicle comprising:
Priority mode selection means capable of setting a motor travel priority mode that preferentially selects a travel mode using the electric motor,
When the motor travel priority mode is selected, the travel mode selection means switches the charge rate lower limit value from a normal value to a motor travel priority value lower than the normal value, and selects the travel mode. A hybrid vehicle drive control system. Further comprising health detection means for detecting the health of the battery;
2. The hybrid vehicle drive control system according to claim 1, wherein the motor travel priority value is variably set so as to increase as the soundness level decreases. Further comprising a remaining capacity calculating means for calculating a remaining capacity of the battery based on the charging rate and the soundness level;
3. The hybrid vehicle drive control system according to claim 2, wherein the travel mode selection unit selects the engine travel mode regardless of the charging rate when the remaining capacity becomes less than a capacity lower limit value. 4. Temperature detecting means for detecting the temperature of the battery,
The said driving mode selection means selects the said engine driving mode regardless of other conditions at the time of the battery cold state where the said temperature is less than reference temperature, The any one of Claims 1-3 characterized by the above-mentioned. Hybrid vehicle drive control system. The hybrid vehicle drive control system according to any one of claims 1 to 4, wherein the hybrid vehicle is a plug-in hybrid vehicle capable of charging the battery with an external power source.

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