JP6354152B2 - Control device and control method for plug-in hybrid vehicle - Google Patents

Description

  The present invention relates to a control device and a control method for a hybrid vehicle having an engine and a motor as a drive source of the vehicle, and more particularly, a plug-in hybrid vehicle capable of charging a battery with an external power source.

  As one of hybrid vehicles having an engine and a motor as drive sources, a plug-in hybrid vehicle that can charge a battery with an external power source such as a commercial power source is known.

  In such a plug-in hybrid vehicle, for example, as disclosed in Patent Document 1, when traveling starts with the battery sufficiently charged by an external power source, the battery charge amount (SOC value) is a predetermined value. Until the level drops, traveling using a motor is basically performed in a so-called CD (Charge Depleting) mode. Thereafter, when the charge amount is reduced to a predetermined level, a so-called CS (Charge Sustain) mode is shifted to a traveling mode in which the engine and the motor are used together so as to maintain the charge amount at a predetermined level.

  Since the CD mode is an operation mode that allows a decrease in the battery charge amount, traveling is basically performed by the motor as described above, and the engine is stopped. However, if the requested output exceeds the motor output limit due to an acceleration request by the driver during driving in the CD mode, the engine is temporarily driven and the engine torque is adjusted so as to compensate for the shortage with respect to the requested output. Be controlled.

JP 2013-129312 A

  During the plug-in hybrid vehicle, particularly in the CD mode, the engine is not continuously operated, and a relatively short time operation is sometimes performed. Therefore, the temperature of the engine and its catalyst device is low. In many cases, the deterioration of HC that increases at the time of engine cold start, particularly HC (so-called tail pipe HC) that is finally discharged to the outside through a catalytic device tends to be a problem.

  Although the temperature rise of the catalytic device depends on the engine load, the required output required for the drive system including the engine and the motor varies in various ways depending on the driver's accelerator operation, so the engine load is constant. However, the mode of change is also various. Therefore, the catalyst activation is relatively fast compared to the increase in HC discharged from the engine, and compared to the increase in HC discharged from the engine, compared with the case where the HC released to the outside is at a sufficiently low level. Thus, there is a large variation between the case where catalyst activation is delayed and the amount of HC emission to the outside increases.

  Therefore, in the case where the engine load fluctuates according to the required output as in the prior art, in order to reliably reduce the amount of HC emissions to the outside, a catalyst device or the like must be configured with a sufficient allowance. There are problems associated with complication of catalyst devices and cost increase.

  In Patent Document 1, the rotational speed and torque of the engine are controlled along the optimum fuel efficiency operation line. However, the rotational speed and torque change when the required output changes.

The present invention includes an engine and a motor as a drive source for a vehicle, a plug that can run using only the engine and the motor and can run only by the motor, and can be charged to a battery by an external power source. A control device or control method for an in-hybrid vehicle,
After the start of travel, the motor travels and the engine is temporarily operated in accordance with the required output until the battery drops to a predetermined charge state, and the engine torque follows the required output. controlled constant by selectively switched according to the operating conditions of the vehicle to the target torque in the target torque of the plurality of stages without, changing in response to a request and outputs the output of the motor, is characterized in that Yes.

  That is, the vehicle basically runs only by the motor until the battery is reduced to a predetermined charged state, but when the required output increases due to the driver's acceleration operation or the like, the engine is started and temporarily operated. At this time, the torque of the engine is controlled to be constant, and the output of the motor is variably controlled so as to match the change in the required output accompanying the accelerator operation, for example.

  Thus, by making the engine torque constant during temporary operation, characteristics such as a temperature rise of the catalyst device can be stably obtained, and the amount of HC discharged to the outside is always stable.

  According to the present invention, the configuration and various settings of the catalyst device for exhaust purification can be targeted for a specific operating point of the engine, and the deterioration of the HC emission amount at the start of the engine can be efficiently performed. It can be suppressed well and stably.

BRIEF DESCRIPTION OF THE DRAWINGS Configuration explanatory drawing which shows the system configuration | structure of the plug-in hybrid vehicle which concerns on this invention. The flowchart of a reference example. The time chart which shows changes, such as an engine torque by this reference example. The flowchart of 1st Example. The time chart which shows changes, such as engine torque by this 1st example. The flowchart of another reference example. The time chart which shows changes, such as an engine torque by this reference example. The time chart which shows an example of the behavior of the comparative example from which an engine torque changes according to a request | requirement output. The time chart which similarly shows the other example of the behavior of a comparative example.

  FIG. 1 is an explanatory diagram showing a system configuration of an FR (front engine / rear drive) type hybrid vehicle as an example of a plug-in hybrid vehicle to which the present invention is applied.

  This hybrid vehicle includes an engine 1 and a motor generator 2 as a vehicle drive source, and a stepped or continuously variable automatic transmission 3 as a speed change mechanism. A first clutch 8 is interposed between the engine 1 and the motor generator 2, and a second clutch 9 is interposed between the motor generator 2 and the transmission 3.

  The engine 1 is composed of, for example, a gasoline engine, and performs start control and stop control based on a control command from an engine control module (ECM) 11, and performs throttle valve opening control, fuel injection amount control, and the like. Is called. A catalyst device 7 made of, for example, a three-way catalyst is interposed in the exhaust passage 6 of the engine 1 for exhaust purification.

  The first clutch 8 provided between the output shaft of the engine 1 and the rotor of the motor generator 2 couples the engine 1 to the motor generator 2 or connects the engine 1 to the motor generator according to the selected travel mode. The engagement / release is controlled by a first clutch hydraulic pressure generated by a hydraulic unit (not shown) based on a control command from the hybrid control module (HCM) 10.

  The motor generator 2 is composed of, for example, a three-phase AC synchronous motor generator, and is connected to a traveling battery 24 via an inverter (not shown). The motor generator 2 receives a power supply from the battery 24 via an inverter and outputs a positive torque based on a control command from the motor controller (MC) 13 and absorbs the torque. Both the regenerative operation of generating power and charging the battery 24 via the inverter is performed.

  The second clutch 9 provided between the rotor of the motor generator 2 and the input shaft of the transmission 3 transmits power between the vehicle drive source including the engine 1 and the motor generator 2 and the drive wheels 5 (rear wheels). Transmission and disconnection are performed, and engagement / release is controlled by a second clutch hydraulic pressure generated by a hydraulic unit (not shown) based on a control command from an automatic transmission control unit (ATCU) 14. In particular, the second clutch 9 can be brought into a slip engagement state in which power is transmitted with slip by variable control of the transmission torque capacity, and enables smooth start in a configuration without a torque converter. At the same time, the realization of creep running is being attempted.

  Here, the second clutch 9 is not actually a single friction element. For example, an appropriate friction clutch or friction brake corresponding to each gear stage included in the automatic transmission 3 is used as the second clutch 9. Is done. Of course, a separate independent friction clutch may be provided as the second clutch 9.

  The output shaft of the automatic transmission 3 is connected to the drive wheels 5 via the final reduction mechanism 4.

  The battery 24 has a configuration in which a large number of cells made of a chargeable / dischargeable secondary battery, for example, a lithium ion battery, are accommodated in a pack case. The battery controller (BC) 12 monitors the discharge and charge of each cell. It is controlled. The battery 24 includes a charging circuit 27 connected to an external power source 25 such as a commercial power source via a connector 26, and charging by the external power source 25 is possible via the charging circuit 27.

  The control system for the plug-in hybrid vehicle is composed mainly of the hybrid control module 10, engine control module 11, battery controller 12, motor controller 13 and automatic transmission control unit 14 described above. They are connected via CAN communication lines 15 that can be mutually connected. Various sensors such as an engine speed sensor 16, an air-fuel ratio sensor 17, an accelerator opening sensor 18, a throttle opening sensor 19, a water temperature sensor 20, a battery temperature sensor 21, a vehicle speed sensor 22, an exhaust temperature sensor 23, and the like are used. The detection signals of these sensors are input to each controller such as the hybrid control module 10 individually or via the CAN communication line 15.

  The plug-in hybrid vehicle configured as described above has a charge depletion (CD) mode that allows a reduction in the charge amount of the battery 24 without using the engine 1 as a running mode, and a charge amount at a predetermined level. And a CS (Charge Sustain) mode in which the engine 1 is used together. That is, it is assumed that the plug-in hybrid vehicle charges the battery 24 by the external power source 25 during parking at night, for example, and when the driving starts with the battery 24 fully charged, the charge amount of the battery 24 The CD mode is selected until the (SOC value) decreases to a predetermined level. After that, when the charge amount decreases to a predetermined level, the mode shifts to the CS mode. The battery 24 whose charge amount has been reduced to a predetermined level is charged again by the external power source 25 during night parking, for example.

  In the CD mode, the first clutch 8 is disengaged and the engine 1 is stopped, so that traveling by only the motor generator 2 (so-called EV traveling) is preferentially performed. However, when the required output exceeds the output limit of the motor generator 2 due to an acceleration request by the driver during the EV traveling only by the motor generator 2, the engine 1 is started and the engine 1 is engaged with the engagement of the first clutch 8. Traveling using both the motor generator 2 is temporarily performed. Since charging using the engine 1 is not performed during the CD mode, the charge amount of the battery 24 gradually decreases.

  In the CS mode, the first clutch 8 is engaged and traveling using the engine 1 and the motor generator 2 as drive sources is preferentially performed. Here, a motor assist travel mode, a travel power generation mode, and an engine travel mode are appropriately selected according to the required output, the SOC value of the battery 24, and the like, and the charge amount (SOC value) of the battery 24 is determined by repeated charge and discharge. Maintained at a predetermined level.

  Next, control of the engine 1 during the CD mode will be described based on FIGS. 2 and 3.

  FIG. 2 is a flowchart showing the flow of control executed during the CD mode. In step 1, it is determined whether or not the vehicle is running in EV. If it is not in EV travel, the routine is terminated. If the vehicle is traveling in EV, the process proceeds to step 2, and the required output required for the hybrid system is calculated based on the accelerator opening and the vehicle speed by the driver's operation. In step 3, it is determined whether the requested output is equal to or greater than a predetermined threshold corresponding to the output limit of the motor generator 2. The threshold value is set to a value that allows for some margin in the output limit of the motor generator 2.

  If the requested output is less than the threshold value, the process proceeds to step 4 to continue the EV traveling by only the motor generator 2.

  If the required output is greater than or equal to the threshold value, the process proceeds from step 3 to steps 5 and 6 to start the engine 1 and operate at a constant torque. In step 7, it is determined whether or not the required output has fallen below the threshold value. If it is less than the threshold value, the engine 1 is stopped in step 8 and the EV running in step 4 is resumed. Until it becomes less than the threshold value in Step 7, the operation of the engine 1 at a constant torque is continued.

  On the other hand, the output of motor generator 2 is variably controlled by another routine (not shown) so that the sum of the outputs of engine 1 and motor generator 2 satisfies the required output.

  FIG. 3 is a time chart showing changes in engine torque and the like due to the above control. From the top, in order, the vehicle speed, the engine start request indicated by ON / OFF, the required output required by the system, the motor generator 2 Changes in output, torque of the engine 1, tail pipe HC (HC concentration at the tail pipe opening end), and catalyst temperature of the catalyst device 7 are shown.

  In this example, the required output exceeds the output limit of the motor generator 2 (actually a threshold value SL with some allowance) from time t1 to time t2 in the process of changing the vehicle speed as shown in the figure. The engine 1 is operated at a constant torque. Then, the output of the motor generator 2 changes corresponding to the change in the required output, and the output corresponding to the required output is obtained by both the engine 1 and the motor generator 2.

  Thus, during the temporary operation of the engine 1 during the CD mode, the engine 1 is operated at a constant torque, so that the temperature of the catalyst device 7 in the exhaust passage 6 rises in the expected manner. That is, the temperature rise of the catalyst can be obtained in a relatively stable manner regardless of the level of the required output or the mode of change. Accordingly, the HC discharged from the engine 1 at a time when the engine is not warmed up is quickly purified in the catalyst device 7, and finally the HC discharged as the tail pipe HC is reduced. In particular, such a relatively low HC emission characteristic can always be obtained stably.

  8 and 9 show time charts in the case where the torque of the engine 1 is changed as the required output changes as a comparative example. The example of FIG. 8 differs from the example of FIG. 9 in the manner of change in the required output. In the example of FIG. 8, since the catalyst temperature has risen relatively early, it is finally discharged to the outside. There are relatively few tail pipes HC. However, in the example of FIG. 9, the catalyst temperature rises relatively slowly due to the relationship with the operating conditions of the engine 1, and as a result, the tail pipe HC that is finally discharged to the outside increases.

  As described above, when the torque of the engine 1 is changed following the required output, the catalyst temperature rises and the timing of catalyst activation is unstable, and the HC generation amount of the engine 1 is not constant. The tail pipe HC may deteriorate.

On the other hand, in the reference examples described with reference to FIGS. 2 and 3, since the amount of HC generated and the catalyst activation in the engine 1 are always obtained with stable characteristics, it is possible to stably obtain a state where the tail pipe HC is small. it can.

Next, FIGS. 4 and 5 show a first embodiment of the present invention in which the torque of the engine 1 is maintained at a plurality of levels. FIG. 4 is a flowchart showing the flow of control executed during the CD mode, and steps 1 to 5, 7, and 8 are not particularly different from the comparative example described above. That is, in step 1, it is determined whether or not EV traveling is in progress. If it is not in EV travel, the routine is terminated. If the vehicle is traveling in EV, the process proceeds to step 2, and the required output required for the hybrid system is calculated based on the accelerator opening and the vehicle speed by the driver's operation. In step 3, it is determined whether the requested output is equal to or greater than a predetermined threshold corresponding to the output limit of the motor generator 2. If the requested output is less than the threshold value, the process proceeds to step 4 to continue the EV traveling by only the motor generator 2.

  If the requested output is greater than or equal to the threshold value, the process proceeds from step 3 to step 5 and the engine 1 is started. In the next steps 9 to 11, the magnitude of the required acceleration for the vehicle speed is determined in four stages. That is, in step 9, whether the required acceleration is greater than or equal to the first threshold, in step 10, whether the requested acceleration is greater than or equal to the second threshold, and in step 11, whether the requested acceleration is greater than or equal to the third threshold. Whether or not is determined. Each threshold has a relationship of “first threshold <second threshold <third threshold”. If the requested acceleration is less than the first threshold value, the process proceeds from step 9 to step 12, the target torque of the engine 1 is set to the first target torque, and the engine 1 is operated at a constant torque. If the requested acceleration is greater than or equal to the first threshold and less than the second threshold, the process proceeds from step 10 to step 13, the target torque of the engine 1 is set to the second target torque, and the engine 1 is operated at a constant torque. If the required acceleration is greater than or equal to the second threshold value and less than the third threshold value, the process proceeds from step 11 to step 14, the target torque of the engine 1 is set to the third target torque, and the engine 1 is operated at a constant torque. If the requested acceleration is equal to or greater than the third threshold value, the process proceeds from step 11 to step 15 where the target torque of the engine 1 is set to the fourth target torque and the engine 1 is operated at a constant torque. Each target torque has a relationship of “first target torque <second target torque <third target torque <fourth target torque”.

  In step 7, it is determined whether or not the required output has fallen below the threshold value. If it is less than the threshold value, the engine 1 is stopped in step 8 and the EV running in step 4 is resumed. Until it becomes less than the threshold value in Step 7, the operation of the engine 1 at a constant torque is continued.

  On the other hand, the output of the motor generator 2 is variably controlled by another routine (not shown) so that the sum of the outputs of the engine 1 and the motor generator 2 satisfies the required output, similarly to the above-described embodiment.

FIG. 5 is a time chart showing changes in engine torque and the like according to the first embodiment. In this example, since the required output exceeds the output limit (threshold value SL) of the motor generator 2 from time t1 to time t2 in the process of changing the vehicle speed as shown in the figure, the operation of the engine 1 is temporarily stopped. Done. At this time, the initial part of the period from the time t1 to the time t2 is operated at a constant torque with the second target torque because the required acceleration is large. The operation shifts to a constant torque operation at the target torque. Then, the output of the motor generator 2 changes corresponding to the change in the required output, and the output corresponding to the required output is obtained by both the engine 1 and the motor generator 2.

Thus, during the temporary operation of the engine 1 during the CD mode, the engine 1 is operated at a constant torque along a plurality of stages of target torque, so that it is relatively stable as in the above-described reference example. As a result, the temperature of the catalyst can be increased, and the HC finally discharged as the tail pipe HC can be reliably reduced. In particular, in this embodiment, the engine 1 is not operated with an excessively large torque, and an unnecessarily large amount of exhaust gas is not generated.

In the first embodiment, multiple stages of torque are selected according to the required acceleration. However, multiple stages of torque may be selected based on other parameters such as the accelerator opening.

Then, 6 and 7, while operating the engine 1 at a constant torque of a plurality of stages, shows a reference example to perform the selection of the target torque in accordance with the temperature state of the motor generator 2 or the battery 24 ing. Although the temperature detection means of the motor generator 2 is not shown in FIG. 1, a temperature sensor (not shown) may be provided in the motor generator 2, or the temperature of the motor generator 2 is indirectly determined from other parameters. It may be estimated as follows.

FIG. 6 is a flowchart showing the flow of control executed during the CD mode, and steps 1 to 5, 7, 8, and 12 to 15 are not particularly different from those in the first embodiment. That is, in step 1, it is determined whether or not EV traveling is in progress. If it is not in EV travel, the routine is terminated. If the vehicle is traveling in EV, the process proceeds to step 2, and the required output required for the hybrid system is calculated based on the accelerator opening and the vehicle speed by the driver's operation. In step 3, it is determined whether the requested output is equal to or greater than a predetermined threshold corresponding to the output limit of the motor generator 2. If the requested output is less than the threshold value, the process proceeds to step 4 to continue the EV traveling by only the motor generator 2.

  If the requested output is greater than or equal to the threshold value, the process proceeds from step 3 to step 5 and the engine 1 is started. In the next steps 9A to 11A, the temperature state of the motor generator 2 or the battery 24 is determined in four stages. That is, in step 9A, whether the temperature of the motor generator 2 or the battery 24 is equal to or higher than the first threshold value, in step 10A, whether it is higher than the second threshold value, or in step 11A, higher than the third threshold value. Whether or not is determined. Each threshold has a relationship of “first threshold <second threshold <third threshold”. Further, each threshold value for motor generator 2 and each threshold value for battery 24 may actually be different values.

  If the temperature of the motor generator 2 or the battery 24 is lower than the first threshold value, the process proceeds from step 9A to step 12, the target torque of the engine 1 is set to the first target torque, and the engine 1 is operated at a constant torque. If the temperature of the motor generator 2 or the battery 24 is equal to or higher than the first threshold value and lower than the second threshold value, the process proceeds from step 10A to step 13, the target torque of the engine 1 is set to the second target torque, and the engine at a constant torque is set. Perform 1 operation. If the temperature of the motor generator 2 or the battery 24 is equal to or higher than the second threshold and lower than the third threshold, the process proceeds from step 11A to step 14, the target torque of the engine 1 is set to the third target torque, and the engine at a constant torque is set. Perform 1 operation. If the temperature of the motor generator 2 or the battery 24 is equal to or higher than the third threshold value, the process proceeds from step 11A to step 15, the target torque of the engine 1 is set to the fourth target torque, and the engine 1 is operated at a constant torque. Each target torque has a relationship of “first target torque <second target torque <third target torque <fourth target torque”.

  In step 7, it is determined whether or not the required output has fallen below the threshold value. If it is less than the threshold value, the engine 1 is stopped in step 8 and the EV running in step 4 is resumed. Until it becomes less than the threshold value in Step 7, the operation of the engine 1 at a constant torque is continued.

  On the other hand, the output of the motor generator 2 is variably controlled by another routine (not shown) so that the sum of the outputs of the engine 1 and the motor generator 2 satisfies the required output, similarly to the above-described embodiment.

FIG. 7 is a time chart showing changes in engine torque and the like according to the above reference example. In this example, since the required output exceeds the output limit (threshold value SL) of the motor generator 2 from time t1 to time t2 in the process of changing the vehicle speed as shown in the figure, the operation of the engine 1 is temporarily stopped. Done. At this time, the temperature of the motor generator 2 or the battery 24 has already exceeded the first threshold at the time t1, and therefore the engine 1 is operated at a constant torque with the second target torque. Thereby, the output of the motor generator 2 is lowered, and the temperatures of the motor generator 2 and the battery 24 are gradually lowered. Therefore, in the middle of the period from time t1 to time t2, the operation shifts to a constant torque operation with the first target torque. Then, the output of the motor generator 2 changes corresponding to the change in the required output, and the output corresponding to the required output is obtained by both the engine 1 and the motor generator 2.

  Thus, during the temporary operation of the engine 1 during the CD mode, the engine 1 is operated at a constant torque along a plurality of stages of target torque, so that it is relatively stable as in the previous embodiment. As a result, the temperature of the catalyst can be increased, and the HC finally discharged as the tail pipe HC can be reliably reduced. In particular, when the motor generator 2 or the battery 24 becomes high temperature, the torque of the motor generator 2 is limited. However, in this embodiment, the sharing ratio on the engine 1 side increases when the motor generator 2 or the battery 24 is high temperature. It is possible to secure the required output while suppressing the pipe HC.

  Note that the present invention is not limited to the plug-in hybrid vehicle having the specific configuration shown in FIG. 1, but is any plug-in hybrid vehicle in which the output of the engine is added to the motor output during the CD mode. Any format can be applied.

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Motor generator 2
DESCRIPTION OF SYMBOLS 3 ... Automatic transmission 7 ... Catalyst apparatus 8 ... 1st clutch 9 ... 2nd clutch 10 ... Hybrid control module 11 ... Engine control module

Claims (2)

A plug-in hybrid vehicle that includes an engine and a motor as a drive source of the vehicle, can run using only the engine and the motor, can run only by the motor, and can be charged to a battery by an external power source. A control device,
After the start of travel, the motor travels and the engine is temporarily operated in accordance with the required output until the battery drops to a predetermined charge state, and the engine torque follows the required output. Without changing the output of the motor in response to the required output, by selectively switching among the target torques in a plurality of stages according to the driving conditions of the vehicle and controlling each target torque to be constant. Control device for plug-in hybrid vehicle. In a plug-in hybrid vehicle having an engine and a motor as a drive source of the vehicle, capable of traveling using only the engine and the motor, traveling only by the motor, and charging the battery by an external power source ,
After the start of travel, the motor travels and the engine is temporarily operated in accordance with the required output until the battery drops to a predetermined charge state, and the engine torque follows the required output. Without changing the output of the motor in response to the required output, by selectively switching among the target torques in a plurality of stages according to the driving conditions of the vehicle and controlling each target torque to be constant. Control method of plug-in hybrid vehicle.

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