JP2023073076A - Hybrid vehicle - Google Patents

Abstract

To provide a technique for sufficiently heating a catalyst prior to start-up of an engine in response to a transition to a HV travel mode from an EV travel mode.SOLUTION: A hybrid vehicle includes an engine and a traveling motor, a battery for supplying power to the motor, a catalyst for purifying exhaust air of the engine, a catalyst heater for heating the catalyst, a first control device for controlling the engine and the motor, and a second control device for controlling the catalyst heater. The first control device is transited to a HV travel mode, when an output voltage of the battery is lower than a predetermined voltage threshold during execution of an EV travel mode. The second control device integrates a charge/discharge current of the battery with time while weighting the charge/discharge current according to a predetermined index, during execution of the EV travel mode, and starts energization to the catalyst heater when the integrated value exceeds a predetermined determination threshold. The predetermined index is at least one of magnitude of the charge/discharge current, a temperature of a battery, an internal resistance of the battery, and a charging rate of the battery.SELECTED DRAWING: Figure 3

Description

The technology disclosed in this specification relates to hybrid vehicles.

Patent Literature 1 describes a hybrid vehicle. A hybrid vehicle includes an engine, a motor for running, a battery that supplies electric power to the motor, a catalyst that purifies exhaust gas from the engine, a catalyst heater, and a control device. When the charging rate of the battery falls below the lower limit of charge, the control device shifts from the EV driving mode in which the vehicle is driven by the motor while the engine is stopped to the HV driving mode in which the vehicle is driven by the engine and/or the motor while the engine is running. In addition, during execution of the EV driving mode, the control device determines that the charging rate of the battery falls below a predetermined threshold value (for example, a value obtained by adding a predetermined value to the lower limit of charge) and the outputtable electric power of the battery is When the sum of the electric power consumed by energizing the catalyst heater and the electric power required to drive the vehicle according to the user's request falls below the sum, energization of the catalyst heater is started.

According to the above configuration, energization of the catalyst heater can be started prior to transition from the EV running mode to the HV running mode. As a result, the catalyst can be heated in advance before the engine is started with the transition to the HV running mode. Furthermore, since sufficient electric power is retained in the battery even after the catalyst heater is energized, it is possible to suppress or avoid a decrease in drivability when shifting from the EV running mode to the HV running mode. .

JP 2013-141893 A

In a hybrid vehicle, the voltage of the battery may drop sharply due to, for example, the occurrence of polarization depending on the history of use of the vehicle and environmental conditions. When the charging rate of the battery is estimated based on the battery voltage, there is a possibility that the EV running mode will be unexpectedly switched to the HV running mode due to a sudden drop in the battery voltage. In this case, the engine may be started when the EV running mode is switched to the HV running mode in a state in which the heating of the catalyst by the catalyst heater is not performed or is insufficient.

In view of the above circumstances, the present specification provides a technique for sufficiently heating the catalyst prior to starting the engine associated with the transition from the EV running mode to the HV running mode.

The technology disclosed in this specification is embodied in a hybrid vehicle. This hybrid vehicle controls an engine and a motor for running, a battery that supplies power to the motor, a catalyst that purifies exhaust gas from the engine, a catalyst heater that heats the catalyst, and controls the engine and the motor. A first controller and a second controller for controlling the catalyst heater are provided. When the output voltage of the battery falls below a predetermined voltage threshold during execution of an EV running mode in which the motor runs while the engine is stopped, the first control device operates the engine while operating the engine. and/or shift to the HV running mode in which the vehicle runs with the motor. The second control device accumulates the charge/discharge current of the battery over time while weighting it according to a predetermined index during execution of the EV running mode, and when the accumulated value exceeds a predetermined judgment threshold, Power supply to the catalyst heater is started. The predetermined index is at least one of the magnitude of the charging/discharging current, the temperature of the battery, the internal resistance of the battery, and the charging rate of the battery.

In the above-described hybrid vehicle, when the accumulated value accumulated over time while weighting the charge/discharge current of the battery according to a predetermined index exceeds a predetermined determination threshold value during execution of the EV driving mode, the catalyst heater is activated. is energized. The predetermined indicator here is at least one of the magnitude of charge/discharge current, battery temperature, battery internal resistance, and battery charging rate. These indices are correlated with the likelihood of polarization occurring in the battery during charging and discharging. can be grasped. Therefore, when the integrated value exceeds a predetermined determination threshold, it is predicted that the battery voltage will drop sharply thereafter. Therefore, according to the above-described configuration, it is possible to start energizing the catalyst heater before the voltage of the battery drops sharply. The catalyst can be sufficiently heated.

1 is a block diagram showing a schematic configuration of a vehicle 10; FIG. The relationship between the elapsed time from the start of discharge and the voltage of the battery 24 is shown for cases where the battery 24 is discharged with four different discharge currents. The discharge current increases in the order of Graph A, Graph B, Graph C and Graph D in FIG. FIG. 3 is a flowchart for explaining a series of processes executed by the first control device 30 and the second control device 32; FIG. 4A shows an example of the change over time of the discharge current during discharging of the battery 24. FIG. The first discharge current A1 is smaller than the second discharge current A2. FIG. 4(B) shows changes over time in the voltage of the battery 24 when discharged at each discharge current shown in FIG. 4(A). V(A1) in FIG. 4(B) corresponds to discharge at the first discharge current A1, and V(A2) in FIG. 4(B) corresponds to discharge at the second discharge current A2. corresponds to FIG. 4(C) shows an example of an integrated value obtained by weighting each discharge current shown in FIG. 4(A) with a predetermined index and integrating it over time. I(A1) in FIG. 4(C) corresponds to the integrated value I obtained by weighting the first discharge current A1 with the magnitude of the first discharge current A1 and integrating it over time. ) corresponds to the integrated value I obtained by weighting the second discharge current A2 by the magnitude of the second discharge current A2 and integrating it over time. FIG. 5A shows an example of changes over time in the charge/discharge current of the battery 24 . FIG. 5(B) shows an example of temporal change of the integrated value I calculated for the charging/discharging current of FIG. 5(A).

In an embodiment of the present technology, the second control device modifies the determination threshold according to at least one of the magnitude of the charge/discharge current, the temperature of the battery, the internal resistance of the battery, and the charging rate of the battery. good. According to such a configuration, in addition to weighting the integrated value in accordance with a predetermined index that correlates with the likelihood of polarization occurring in the battery, the predetermined determination threshold also correlates with the likelihood of polarization occurring in the battery. It can be modified according to the index. Therefore, it is possible to accurately predict that the voltage of the battery will drop rapidly.

In some of the above-described embodiments, the second control device starts energizing the catalyst heater even when the maximum power that the battery can output falls below a predetermined power threshold during execution of the EV running mode. good. The predetermined power threshold here is, for example, the sum of the power consumed by energizing the catalyst heater and the power required to meet the standards of the real driving emissions (RDE) test. may be set as According to such a configuration, it is possible to appropriately suppress the exhaust of the engine even after the EV driving mode is shifted to the HV driving mode.

A hybrid vehicle 10 (hereinafter referred to as "vehicle 10") will be described with reference to the drawings. A vehicle 10 of this embodiment belongs to an electric vehicle having a motor 20 for driving wheels 14 and 16, and is typically an electric vehicle (so-called automobile) that travels on a road surface. However, part or all of the technology described in this embodiment can be similarly applied to an electric vehicle that runs on a track. Further, the vehicle 10 is not limited to being operated by a user, and may be remotely operated by an external device or autonomously traveling.

As shown in FIG. 1, a vehicle 10 includes a vehicle body 12 and a plurality of wheels 14,16. The vehicle body 12 has a passenger compartment, which is a space for occupants. A plurality of wheels 14 , 16 are rotatably attached to the vehicle body 12 . The plurality of wheels 14 , 16 includes a pair of drive wheels 14 and a pair of driven wheels 16 . As an example, the pair of drive wheels 14 are front wheels positioned at the front of the vehicle body 12 , and the pair of driven wheels 16 are rear wheels positioned at the rear of the vehicle body 12 . A pair of driving wheels 14 are arranged coaxially with each other, and a pair of driven wheels 16 are also arranged coaxially with each other. Note that the number of wheels 14 and 16 is not limited to four. Although not particularly limited, the vehicle body 12 is made of metal such as steel or aluminum alloy.

As shown in FIG. 1 , vehicle 10 further includes engine 18 , motor 20 , and power distribution device 22 . The engine 18 is a heat engine, such as a gasoline engine or a diesel engine, that burns fuel to generate power. Motor 20 is, for example, a three-phase motor generator having U-phase, V-phase and W-phase. An output shaft of the engine 18 is connected to a power distribution device 22, and the power distribution device 22 is connected to each of the pair of drive wheels 14 and the motor 20. As shown in FIG. Therefore, the power output from the engine 18 is distributed to the pair of drive wheels 14 and the motor 20 by the power distribution device 22 . In other words, the engine 18 is a power source that drives the pair of drive wheels 14 and also a power source that drives the motor 20 that functions as a generator.

The motor 20 functions as a prime mover that drives the pair of drive wheels 14 and also functions as a generator. A motor 20 is connected to the pair of drive wheels 14 via a power distribution device 22 . Therefore, the motor 20 can function as a prime mover for driving the pair of drive wheels 14 together with the engine 18 . Further, the motor 20 is driven by the power of the engine 18 distributed by the power distribution device 22, so that the motor 20 can function as a generator. In addition, the vehicle 10 can regeneratively brake the pair of drive wheels 14 by causing the motor 20 to function as a generator when deceleration is required. Note that the engine 18 and the motor 20 are not limited to the pair of drive wheels 14 as long as they are configured to drive at least one of the plurality of wheels 14 and 16 .

As shown in FIG. 1 , vehicle 10 further includes battery 24 . The battery 24 is a secondary battery in which a plurality of battery cells are connected in series, and is configured to be repeatedly rechargeable with external power. The battery 24 is connected to the motor 20 , can supply driving power to the motor 20 , and can be charged by power generated by the motor 20 . Although not shown, a plurality of inverters are provided between the battery 24 and the motor 20, and power conversion can be performed between the DC power of the battery 24 and the AC power of the motor 20. . Although not particularly limited, a DC-DC converter may be further provided between the battery 24 and the motor 20 when the rated voltage of the battery 24 and the rated voltage of the motor 20 are different from each other. Although it is an example, the battery 24 is a lithium ion battery, a nickel metal hydride battery cell, or the like.

As shown in FIG. 1 , vehicle 10 further includes catalyst 26 and catalyst heater 28 . The catalyst 26 is a catalyst that purifies exhaust gas from the engine 18 . A catalyst heater 28 is a device for heating the catalyst 26 . The catalyst 26 is provided, for example, in a passage through which the exhaust gas from the engine 18 passes, and purifies the exhaust gas discharged from the engine 18 . As a result, the exhaust purified by the catalyst 26 is discharged to the atmosphere. The catalyst heater 28 is provided adjacent to the catalyst 26 and is configured to heat the catalyst 26 by generating heat from the power supplied from the battery 24 .

As shown in FIG. 1 , vehicle 10 further includes a first control device 30 and a second control device 32 . A first controller 30 is communicatively connected to the engine 18 and the motor 20 and can monitor and control their operation. A second controller 32 is communicatively connected to the catalytic heater 28 and can monitor and control its operation. For example, user operation information and vehicle information indicating the state of the vehicle 10 are input to the first control device 30 . The operation information is, for example, accelerator opening information indicating the amount of operation of the accelerator pedal by the user, and brake depression force information indicating the amount of brake operation by the user. The vehicle information is, for example, vehicle speed information indicating the speed of the vehicle 10, and battery information such as the output voltage of the battery 24, charging/discharging current, temperature, internal resistance, and charging rate. The first control device 30 controls the operation of each part of the vehicle 10 described above according to the input operation information and vehicle information. The second controller 32 can initiate energization of the catalyst heater 28 by the battery 24 . The first control device 30 and the second control device 32 are connected so as to be able to communicate with each other. Although details will be described later, the second control device 32 can identify an appropriate timing to start energizing the catalyst heater 28 based on the vehicle information transmitted from the first control device 30 .

First control device 30 can selectively execute the EV running mode and the HV running mode. Specifically, the first control device 30 is configured to shift to the HV running mode when the output voltage of the battery 24 falls below a predetermined voltage threshold VS during execution of the EV running mode. Here, the EV driving mode is a driving mode in which the engine 18 is stopped and the motor 20 is used for driving. On the other hand, the HV travel mode is a travel mode in which the vehicle travels with the engine 18 and/or the motor 20 while the engine 18 is being operated. Note that the predetermined voltage threshold VS may be empirically set based on the past travel history or the like, or may be uniformly set based on the type of the battery 24 mounted on the vehicle 10 or the like.

In the vehicle 10 of this embodiment, as shown in FIG. 2, the voltage of the battery 24 may drop suddenly due to the occurrence of polarization or the like depending on the history of use of the vehicle 10 and environmental conditions. FIG. 2 shows the relationship between the elapsed time from the start of discharge and the voltage of the battery 24 when the battery 24 is discharged with four different discharge currents. The discharge current increases in the order of . The time required for the voltage of the battery 24 to drop from the first voltage V1 to the second voltage V2 becomes significantly shorter as the discharge current increases (that is, TD<TC<TB<TA). Due to the rapid drop in the voltage of the battery 24 in this way, there is a risk that the EV running mode will be switched to the HV running mode unexpectedly. In this case, the engine 18 may be started when the EV running mode is switched to the HV running mode while the catalyst heater 28 is not heating the catalyst 26 sufficiently or heating the catalyst 26 insufficiently.

Regarding the above point, the first control device 30 and the second control device 32 are configured to execute the series of processes shown in FIG. Thereby, the second control device 32 can specify an appropriate timing to start energizing the catalyst heater 28 . A series of processes executed by the first control device 30 and the second control device 32 will be described below with reference to FIGS.

As shown in FIG. 3, first, the second control device 32 determines whether or not the first control device 30 is executing the EV driving mode (step S10). In addition to the vehicle information input to the first control device 30 , the second control device 32 can acquire from the first control device 30 the running mode being executed by the first control device 30 . In the case of YES in step S10, the second control device 32 accumulates the charge/discharge current of the battery 24 over time while weighting it according to a predetermined index (step S12). On the other hand, if NO in step S10, the second control device 32 terminates the series of processes.

Details of the processing in step S12 will be described with reference to FIG. For convenience of explanation, the case where the battery 24 is discharged with each of the first discharge current A1 and the second discharge current A2 will be compared. The first discharge current A1 in FIG. 4A is smaller than the second discharge current A2. For example, the first discharge current A1 is 100A and the second discharge current A2 is 200A. As shown in FIG. 4B, the larger the discharge current, the shorter the time required for the voltage of the battery 24 to decrease by the predetermined voltage width ΔV. In other words, since the magnitude of the charge/discharge current correlates with the likelihood of polarization occurring in the battery 24 during charge/discharge, each charge/discharge current is weighted by the magnitude of the charge/discharge current and integrated over time. Based on the integrated value I (see FIG. 4C), it is possible to objectively grasp the degree of progress of polarization at that time. In this embodiment, the integrated value I is calculated after weighting (that is, correction) such that the larger the discharge current of the battery 24, the larger the discharge current value. As a result, even if the amount of electric power discharged from the battery 24 (that is, the simple integrated value of the discharge current) is the same, the integrated value I calculated when a large current is discharged in a short time is calculated. becomes larger. Note that the charge/discharge current of the battery 24 is an index that takes positive and negative values, and the discharge current when the battery 24 is discharged is represented by a positive value, and the charge current when the battery 24 is charged is represented by a negative value. is represented by Therefore, while the battery 24 is being charged, the integrated value I is subtracted according to the magnitude of the charging current. The charge/discharge current of the battery 24 is configured to be transmitted from the first control device 30 to the second control device 32 as described above. When the weighted integrated value I exceeds the predetermined determination threshold value X, it is predicted that the voltage of the battery 24 will drop sharply thereafter.

In this embodiment, instead of or in addition to the magnitude of the charge/discharge current described above, while weighting according to at least one of the temperature of the battery 24, the internal resistance of the battery 24, and the charging rate of the battery 24, The charge/discharge current of the battery 24 can be integrated over time. The temperature of the battery 24, the internal resistance of the battery 24, and the charging rate of the battery 24 are also correlated with the likelihood of polarization occurring in the battery 24 during charging/discharging, similarly to the magnitude of the charging/discharging current. By weighting and accumulating the charging/discharging currents according to , it is possible to objectively grasp the degree of progress of polarization at that time. In this case, the integration value I may be calculated after weighting such that the charge/discharge current value increases as the temperature of the battery 24 decreases. Additionally or alternatively, the integration value I may be calculated after weighting such that the charge/discharge current value increases as the internal resistance of the battery 24 increases. Additionally or alternatively, the integration value I may be calculated after weighting such that the charging/discharging current value increases as the charging rate of the battery 24 decreases. The temperature, internal resistance, and charge rate of the battery 24 are also configured to be transmitted from the first controller 30 to the second controller 32, as previously described. Note that "at least one of the magnitude of the charge/discharge current, the temperature of the battery 24, the internal resistance of the battery 24, and the charging rate of the battery 24" in this embodiment corresponds to the "predetermined index" in the present technology. .

When the integrated value I calculated in step S12 exceeds the predetermined determination threshold value X (YES in step S14), the second control device 32 starts energizing the catalyst heater 28 from the battery 24 (step S16). At this time, the second controller 32 notifies the first controller 30 that energization of the catalyst heater 28 has started. The first control device 30 that has received the notification determines whether or not the output voltage of the battery 24 has fallen below a predetermined voltage threshold VS (step S18). In the case of YES in step S18, the first control device 30 shifts from the EV running mode to the HV running mode (step S20) and starts the engine 18. In the case of NO in step S18, the first control device 30 terminates the series of processes without shifting to the HV running mode. In this case, although not particularly limited, the first control device 30 may notify the second control device 32 of not shifting to the HV running mode (that is, continuing the EV running mode). The second control device 32 that has received the notification may keep the catalyst 26 warm by controlling the energization of the catalyst heater 28 by the battery 24 .

When the integrated value I calculated in step S12 does not exceed the predetermined determination threshold value X (NO in step S14), the second control device 32 determines whether the maximum power that the battery 24 can output is below the predetermined power threshold value. It is determined whether or not (step S22). Although not particularly limited, the maximum power that the battery 24 can output here is an estimated value determined by the temperature and charging rate of the battery 24 . Further, the predetermined power threshold is, for example, the sum of the power consumed by energizing the catalyst heater 28 and the power required to meet the standards of the real driving emissions (RDE) test. set.

Also in the case of YES in step S22, the second control device 32 starts energizing the catalyst heater 28 (step S24) and notifies the first control device 30 to that effect. When the first control device 30 determines that the output voltage of the battery 24 has fallen below the predetermined voltage threshold VS (YES in step S26), it shifts from the EV running mode to the HV running mode (step S28), and starts the engine 18. do. On the other hand, if the output voltage of the battery 24 is equal to or higher than the predetermined voltage threshold VS (NO in step S26), the first control device 30 terminates the series of processes without shifting to the HV running mode. do. Here, the processing from step S24 to step S28 is the same as the processing from step S16 to step S20. In the case of NO in step S22, the second control device 32 terminates the series of processes.

In the vehicle 10 described above, when the integrated value I that is integrated over time while weighting the charging/discharging current of the battery 24 according to a predetermined index exceeds a predetermined determination threshold value X during execution of the EV driving mode, Power supply to the catalyst heater 28 is started. The predetermined indicator here is at least one of the magnitude of the charge/discharge current, the temperature of the battery 24 , the internal resistance of the battery 24 , and the charging rate of the battery 24 . These indices correlate with the likelihood of polarization occurring in the battery 24 during charging and discharging. can be grasped. Therefore, when the integrated value I exceeds the predetermined determination threshold value X, it is predicted that the voltage of the battery 24 will drop sharply thereafter. Therefore, according to the above-described configuration, it is possible to start energizing the catalyst heater 28 before the voltage of the battery 24 drops sharply, so that the engine 18 can be started when the EV driving mode is changed to the HV driving mode. Prior to this, the catalyst 26 can be sufficiently heated.

Although it is an example, the second control device 32 of the present embodiment weights according to at least one of the magnitude of the charging and discharging current, the temperature of the battery 24, the internal resistance of the battery 24, and the charging rate of the battery 24 The predetermined determination threshold value X for the integrated value I that is integrated may be modified. An example of correcting the determination threshold value X according to the charging rate of the battery 24 will be described with reference to FIG. FIG. 5(A) shows an example of the change over time of the charge/discharge current of the battery 24, and FIG. 5(B) shows an example of the change over time of the integrated value I calculated at that time. Although not particularly limited, in this example, the integrated value I is calculated to increase when the charge/discharge current exceeds the reference value AS, and the integrated value I decreases when the charge/discharge current falls below the reference value AS. Calculated. When the determination threshold value X is corrected according to the state of charge of the battery 24, the determination threshold value X for the integrated value I should be made smaller as the state of charge of the battery 24 is lower. That is, as shown in FIG. 5B, as the charging rate of the battery 24 decreases, the determination threshold value X for the integrated value I changes from the first determination threshold value X1 to the second determination threshold value X2 to the third determination threshold value X3. should be made smaller in the order of As a result, the smaller the charging rate of the battery 24 is, the earlier the timing at which the catalyst heater 28 is started to be energized.

Similarly, when the determination threshold value X is corrected according to the magnitude of the charge/discharge current, the determination threshold value X for the integrated value I should be made smaller as the charge/discharge current value increases. Further, when the determination threshold X is corrected according to the temperature of the battery 24, the determination threshold X for the integrated value I should be made smaller as the temperature of the battery 24 is lower. Further, when the determination threshold value X is corrected according to the internal resistance of the battery 24, the determination threshold value X for the integrated value I should be made smaller as the internal resistance of the battery 24 increases.

According to the above configuration, in addition to weighting the integrated value I in accordance with a predetermined index that correlates with the likelihood of polarization occurring in the battery 24, the predetermined judgment threshold value X is also used to determine the likelihood of polarization occurring in the battery 24. can be modified according to an index that correlates with Therefore, it is possible to accurately predict that the voltage of the battery 24 will drop rapidly.

Although several specific examples have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness either singly or in combination.

10: Vehicle 12: Vehicle Body 14: Drive Wheel 16: Driven Wheel 18: Engine 20: Motor 22: Power Distribution Device 24: Battery 26: Catalyst 28: Catalyst Heater 30: First Control Device 32: Second Control Device

Claims (3)

an engine and a motor for running;
a battery that powers the motor;
a catalyst for purifying the exhaust of the engine;
a catalyst heater that heats the catalyst;
a first control device that controls the engine and the motor;
a second controller that controls the catalyst heater;
with
When the output voltage of the battery falls below a predetermined voltage threshold during execution of an EV running mode in which the motor runs while the engine is stopped, the first control device operates the engine while operating the engine. and/or transition to an HV travel mode in which the vehicle travels with the motor,
The second control device accumulates the charge/discharge current of the battery over time while weighting it according to a predetermined index during execution of the EV running mode, and when the accumulated value exceeds a predetermined judgment threshold, starting to energize the catalyst heater;
The predetermined index is at least one of the magnitude of the charging and discharging current, the temperature of the battery, the internal resistance of the battery, and the charging rate of the battery.
hybrid car. The second control device corrects the determination threshold according to at least one of the magnitude of the charge/discharge current, the temperature of the battery, the internal resistance of the battery, and the charging rate of the battery. 1. The hybrid vehicle according to 1. 3. The second control device starts energizing the catalyst heater even when the maximum power that can be output from the battery falls below a predetermined power threshold during execution of the EV drive mode. hybrid vehicle described in .

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