JP2013047062A - Hybrid vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid vehicle control device able to suppress overlapping of: a rotation inverting timing at which a torque acting on a drive shaft inverts from a negative torque to a positive torque during traveling driven only by a motor; and an internal combustion engine starting timing.SOLUTION: In a high vehicle speed region during traveling of the hybrid vehicle driven only by a second motor-generator 5, a threshold used for the determination whether the internal combustion engine 1 begins starting is changed to a value higher than a value that intends fuel consumption improvement in the internal combustion engine 1. Accordingly, when the hybrid vehicle during traveling driven only by the second motor-generator 5 is accelerated from the deceleration state, and when an output torque of the second motor-generator 5 increases following increase of required traveling power thereby causing the torque acting on the drive shaft 3 to be inverted, the traveling power does not become equal to or more than the threshold easily. Consequently, it becomes difficult to cause the starting of the internal combustion engine 1 in a stopped state.

Description

  The present invention relates to a control device for a hybrid vehicle.

  A hybrid vehicle equipped with a motor and an internal combustion engine as a prime mover travels by transmitting the output torque of the prime mover to wheels via a gear mechanism. In such a hybrid vehicle, with the intention of improving the fuel efficiency of an internal combustion engine mounted as a prime mover, the vehicle travels only by driving the motor when the travel power required by the vehicle is less than the threshold, while the travel power exceeds the threshold. When this happens, the engine is started to run by driving the internal combustion engine.

  In the hybrid vehicle described above, when the vehicle is accelerated from the deceleration state while traveling only by driving the motor, the torque acting on the drive shaft of the vehicle is increased in the direction opposite to the rotation of the wheel as the motor output torque increases. The torque (negative torque) is reversed to the torque in the same direction as the wheel rotation (positive torque). When the torque acting on the drive shaft is reversed in this way, the gears that mesh with each other in the gear mechanism rotate relative to each other by the amount of backlash, and rattling noise is generated between the gears that mesh with each other with the relative rotation. In order to suppress the rattling noise at this time, as shown in Patent Document 1, when the torque acting on the drive shaft is reversed from negative torque to positive torque while the hybrid vehicle is driven only by the motor, It has been proposed to gradually change (increase) the output torque.

  Further, as described above, when the output torque of the motor is gradually changed, if the internal combustion engine is started and the output torque of the engine increases and the positive torque acting on the drive shaft suddenly increases, a shock is caused accordingly. The gear rattling noise between the gears that are generated or mesh with each other increases. For this reason, in Patent Document 1, when the output torque of the motor is gradually changed as described above, the start of the internal combustion engine is prohibited, thereby suppressing the occurrence of shock and the increase in rattling noise described above. ing.

JP 2005-232993 A (paragraphs [0027] to [0035])

  By the way, in order to prohibit the start of the internal combustion engine as in Patent Document 1, a period in which the torque acting on the drive shaft reverses from a negative torque to a positive torque as the motor output torque increases as a period in which the prohibition should be performed. That is, it is necessary to accurately determine the period during which the motor output torque is gradually increased.

  However, it is not always possible to accurately determine such a period, and if the determination cannot be performed accurately, there is a possibility that the period during which the start of the internal combustion engine is prohibited cannot be set to an appropriate period. If the period during which the start of the internal combustion engine is prohibited cannot be an appropriate period, that is, a period in which the torque acting on the drive shaft is reversed from negative torque to positive torque, the internal combustion engine is started during that period. There is a risk. In other words, when the torque acting on the drive shaft is reversed from the negative torque to the positive torque during traveling only by driving the motor, the reversal may be overlapped with the start of the internal combustion engine.

  When the reverse of the torque acting on the drive shaft from the negative torque to the positive torque overlaps with the start of the internal combustion engine, the positive torque acting on the drive shaft due to the increase in the output torque of the engine accompanying the start of the internal combustion engine. As a result, a shock is generated, and the rattling noise between the gears meshing with each other in the gear mechanism increases.

  The present invention has been made in view of such circumstances, and its purpose is that when the torque acting on the drive shaft reverses from negative torque to positive torque during traveling by only driving the motor, the inversion and internal combustion An object of the present invention is to provide a control device for a hybrid vehicle that can prevent the start of the engine from overlapping.

  According to the first aspect of the present invention, when the output torque of the motor and the internal combustion engine mounted on the hybrid vehicle as the prime mover is transmitted to the wheels via the gear mechanism, the hybrid vehicle travels thereby. When the traveling power required by the hybrid vehicle is less than the threshold, traveling is performed only by driving the motor. On the other hand, when the traveling power exceeds the threshold, the engine is started to travel by driving the internal combustion engine. The Here, the threshold value is variably set by the setting means based on the vehicle speed so as to realize improvement in fuel consumption of the internal combustion engine. However, when the threshold value is variably set based on the vehicle speed in this way, the threshold value tends to be small in the high vehicle speed region. Due to this, the following situation may occur while the hybrid vehicle is traveling only by driving the motor in the high vehicle speed region.

  In other words, when a hybrid vehicle that is running only by driving the motor is accelerated from the deceleration state, the output torque of the motor increases as the required running power increases, and the running power becomes equal to or greater than the threshold value and is stopped. The internal combustion engine at is started. In this case, the torque acting on the drive shaft of the hybrid vehicle is reversed from the torque in the direction opposite to the rotation of the wheel (negative torque) to the torque in the same direction as the rotation of the wheel (positive torque) due to the increase in the output torque of the motor. The period during which the inversion is performed overlaps the start of the internal combustion engine. As a result, when the torque acting on the drive shaft reverses from the negative torque to the positive torque, the output torque of the engine suddenly increases as the internal combustion engine starts, and the positive torque acting on the drive shaft also increases rapidly. And since the positive torque which acts on a drive shaft increases suddenly in this way, a shock arises or the rattling sound of the gears which mutually mesh in a gear mechanism will become large.

  In order to cope with such a problem, in the first aspect of the invention, in the high vehicle speed range, the threshold value is changed to a value larger than the value variably set by the setting means. In this way, by changing the threshold value to a large value in the high vehicle speed region, problems such as the occurrence of shock and increase in rattling noise occur during the traveling of the hybrid vehicle only by driving the motor in the high vehicle speed region. This can be suppressed. More specifically, when a hybrid vehicle that is running only by driving a motor is accelerated from a deceleration state, when the output torque of the motor increases with an increase in required running power, the running power is less likely to exceed a threshold value. For this reason, the internal combustion engine that is stopped at that time is less likely to start. In this case, when the torque acting on the drive shaft of the hybrid vehicle is reversed from the negative torque to the positive torque due to the increase in the output torque of the motor, the overlap of the period during which the reversal is performed and the start of the internal combustion engine is suppressed. Incidentally, it is not necessary to discriminate the above period when suppressing the overlap of the period in which the torque acting on the drive shaft reverses and the start of the internal combustion engine in this way, so that such discrimination cannot be performed accurately. As a result, the above period and the start of the internal combustion engine do not overlap. Then, by suppressing the overlap between the period and the start of the internal combustion engine, it is possible to suppress a sudden increase in the output torque of the internal combustion engine with the start of the internal combustion engine when the torque is reversed, and thus act on the drive shaft. A sudden increase in positive torque can also be suppressed. Therefore, it is possible to suppress the occurrence of the shock and the increase of the rattling noise due to a rapid increase in the positive torque acting on the drive shaft.

  Further, when the threshold value is variably set based on the vehicle speed so as to improve the fuel consumption of the internal combustion engine, the threshold value is variable based on the vehicle speed so that the threshold value decreases as the vehicle speed increases. Will be set. At this time, it is preferable to change the threshold value based on the vehicle speed through the changing means so that the threshold value becomes larger as the vehicle speed becomes higher in the high vehicle speed region. This is because the higher the vehicle speed, the more likely the required driving power tends to increase when accelerating the hybrid vehicle that is running only by driving the motor from the deceleration state. Even under such a tendency, the driving power exceeds the threshold value. This is because it is effective to make the threshold variable as described above according to the vehicle speed.

  In addition, as the setting means and the changing means, it is conceivable to employ the invention according to claim 3. In this case, as the setting means, one that sets the threshold value by referring to a map based on the vehicle speed when the vehicle speed is lower than the high vehicle speed region is adopted. Further, as the changing means, when the vehicle speed is in the high vehicle speed region, it is assumed that the threshold value is set by the setting means based on the vehicle speed by setting the threshold value with reference to a map based on the vehicle speed. A value that is larger than the threshold value in this case is employed.

1 is a schematic diagram illustrating a configuration of a hybrid vehicle to which a control device of the present embodiment is applied. The graph which shows the change of the threshold value with respect to the change of a vehicle speed. The flowchart which shows the starting procedure of the internal combustion engine in the driving | running | working of the hybrid vehicle only by the drive of a 2nd motor generator.

Hereinafter, an embodiment in which the present invention is embodied in a control device for a hybrid vehicle in which an internal combustion engine and a motor are mounted as a prime mover will be described with reference to FIGS.
In the hybrid vehicle shown in FIG. 1, the power output from the internal combustion engine 1 is transmitted to the drive shaft 3 of the vehicle via a counter gear 12 and a final gear 13 by a power split gear mechanism 2 including a planetary gear or the like. And the power transmitted to the first motor generator 4. Further, the power output from the second motor generator 5 is transmitted to the drive shaft 3 of the hybrid vehicle via a reduction gear mechanism 14 including a planetary gear, the counter gear 12, and the final gear 13. When the wheels 11 connected to the drive shaft 3 are rotated by the transmission of power to the drive shaft 3, the hybrid vehicle travels. The power split gear mechanism 2, the reduction gear mechanism 14, the counter gear 12, and the final gear 13 function as a gear mechanism for transmitting the output torque of the prime mover in the hybrid vehicle to the drive shaft 3 and the wheels 11.

  The first motor generator 4 functions mainly as a generator, but also functions as a motor depending on the operating state of the hybrid vehicle such as when the internal combustion engine 1 is started. The second motor generator 5 mainly functions as a motor, but also functions as a generator depending on the operating state of the vehicle such as when the hybrid vehicle is decelerated. The hybrid vehicle is provided with an inverter 7 that controls input / output of electric power between the battery 6 and the first and second motor generators 4, 5. The inverter 7 supplies, for example, electric power obtained by the first motor generator 4 that functions mainly as a generator to the battery 6 to charge the battery 6, and also functions as a second motor that mainly functions as a motor. Electric power is supplied from the battery 6 to the motor generator 5.

  The hybrid vehicle is provided with an electronic control unit 15 that controls various devices mounted on the vehicle. The electronic control unit 15 includes a CPU that executes arithmetic processing related to the control of the various devices, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores the arithmetic results of the CPU, and the like. It has input / output ports for inputting and outputting signals between them. An input port of the electronic control unit 15 includes an accelerator position sensor 9 that detects an operation amount (accelerator operation amount) of an accelerator pedal 8 that is operated by a driver of the hybrid vehicle, and a vehicle speed sensor that detects a vehicle speed of the hybrid vehicle. Signals from various sensors such as 10 are input. On the other hand, in the output port of the electronic control unit 15, drive circuits for various devices for operating the internal combustion engine 1, drive circuit for the first motor generator 4, drive circuit for the second motor generator 5, and drive circuit for the inverter 7. Etc. are connected.

  The electronic control unit 15 obtains the traveling power required by the hybrid vehicle based on the driving state such as the vehicle speed and the accelerator operation amount, the power output from the internal combustion engine 1 and the second motor generator so as to obtain the obtained traveling power. The power output from 5 is controlled. Such control of the internal combustion engine 1 and the second motor generator 5 is performed in consideration of minimizing energy consumption associated with the driving thereof. For example, when the traveling power required for the hybrid vehicle is less than a threshold value, the operation of the internal combustion engine 1 is stopped while the second motor generator 5 functions as a motor in order to improve the fuel consumption of the internal combustion engine 1. The vehicle travels only by driving the second motor generator 5. On the other hand, when the required travel power exceeds a threshold value, the internal combustion engine 1 is started and the operation of the engine 1 is performed while the second motor generator 5 functions as a motor so that the travel power can be quickly obtained. Is also performed by using the second motor generator 5 and the internal combustion engine 1 together.

Next, the threshold value for determining whether to operate the internal combustion engine 1 or stop the operation will be described in detail.
The threshold value is variably set based on the vehicle speed so that the fuel efficiency of the internal combustion engine 1 can be improved. The threshold value variably set in this way gradually decreases as the vehicle speed increases, for example, as indicated by a broken line in FIG. 2, and becomes a small value in a high vehicle speed region (region of the vehicle speed V0 or more in the drawing). There is a tendency. As described above, since the threshold value is small in the high vehicle speed region, the following situation may occur while the hybrid vehicle is traveling only by driving the second motor generator 5 in the high vehicle speed region. There is.

  That is, when a hybrid vehicle that is traveling only by driving of the second motor generator 5 and is in a decelerating state is accelerated by the driver's depression of the accelerator pedal 8, the second motor generator is generated with an increase in required traveling power. As the output torque of No. 5 increases, the running power becomes equal to or greater than the threshold value, and the internal combustion engine 1 in a stopped state is started. In this case, the torque acting on the drive shaft 3 of the hybrid vehicle due to the increase in the output torque of the second motor generator 5 changes from the torque in the direction opposite to the rotation of the wheel 11 (negative torque) to the torque in the same direction as the rotation of the wheel 11 (positive torque). ) And the start of the internal combustion engine 1 overlap.

  When the torque acting on the drive shaft 3 is reversed from the negative torque to the positive torque, the gears meshing with each other in the gear mechanism (the reduction gear mechanism 14, the counter gear 12, the final gear 13, etc.) rotate relative to each other by the amount of backlash, With the relative rotation, rattling noise is generated between the gears meshing with each other. Further, if the period in which the torque acting on the drive shaft 3 is reversed and the start of the internal combustion engine 1 overlap, when the torque acting on the drive shaft 3 reverses from negative torque to positive torque, the internal combustion engine 1 As the engine starts, the output torque of the engine 1 increases rapidly, and the positive torque acting on the drive shaft 3 also increases rapidly. Then, as described above, the positive torque acting on the drive shaft 3 is suddenly increased, so that a shock is generated or the rattling noise between the gears meshing with each other in the gear mechanism is increased.

  In order to deal with such a problem, in the present embodiment, in the high vehicle speed range, the threshold value is larger than a value indicated by a broken line (a value intended to improve fuel consumption of the internal combustion engine 1), for example, a value indicated by a two-dot chain line in the figure. To be changed. Specifically, as apparent from the two-dot chain line, the threshold value is changed based on the vehicle speed so that the threshold value increases as the vehicle speed increases. In this way, by changing the threshold value to a large value in the high vehicle speed region, the above-described shock generation and rattling noise are generated during the traveling of the hybrid vehicle only by driving the second motor generator 5 in the high vehicle speed region. The occurrence of a problem such as an increase can be suppressed.

  Specifically, when the hybrid vehicle that is running only by driving the second motor generator 5 is accelerated from the deceleration state, the output torque of the second motor generator 5 increases as the required running power increases. Since the traveling power does not easily exceed the threshold value, the internal combustion engine 1 that is stopped at that time is less likely to start. In this case, when the torque acting on the drive shaft 3 of the hybrid vehicle is reversed from the negative torque to the positive torque due to the increase in the output torque of the second motor generator 5, the period of the reversal overlaps the start of the start of the internal combustion engine 1. That is suppressed. As a result, a sudden increase in the output torque of the internal combustion engine 1 at the start of the internal combustion engine 1 when the torque is reversed is suppressed, and consequently a rapid increase in the positive torque acting on the drive shaft 3 is also suppressed. Accordingly, it is possible to suppress the occurrence of the shock and the increase of the rattling noise due to a sudden increase in the positive torque acting on the drive shaft 3.

  Next, starting of the internal combustion engine 1 while the hybrid vehicle is traveling only by driving the second motor generator 5 will be described with reference to a flowchart of FIG. 3 showing an engine starting routine. This engine start routine is periodically executed through the electronic control unit 15 by, for example, a time interruption at predetermined time intervals.

  In this routine, it is determined whether or not the hybrid vehicle is traveling only by driving the second motor generator 5 and the operation of the internal combustion engine 1 is stopped (S101). If the determination is affirmative, the threshold value used for determining whether to start the operation of the internal combustion engine 1 or to maintain the stop of the operation is obtained with reference to a map based on the vehicle speed at that time (S102). ). In this map, the relationship between the vehicle speed and the threshold indicated by the broken line in FIG. 2 is defined in the low vehicle speed region below the vehicle speed V0, and the vehicle speed and threshold indicated by the two-dot chain line in FIG. 2 in the high vehicle speed region above the vehicle speed V0. The relationship is defined. Therefore, the threshold value obtained with reference to this map changes as shown by the solid line in FIG. 2 with respect to the change in the vehicle speed.

  The electronic control unit 15 functions as setting means for variably setting the threshold value based on the vehicle speed when the threshold value is obtained by referring to the map based on the vehicle speed in the low vehicle speed region. Further, when the electronic control unit 15 obtains a threshold value with reference to the map based on the vehicle speed in the high vehicle speed region, the threshold value is larger than a value variably set by the setting means (broken line in FIG. 2). It functions as a changing means for changing to a value (two-dot chain line in FIG. 2).

  After the threshold value is obtained as described above, it is determined whether or not the traveling power obtained from the accelerator operation amount and the vehicle speed, that is, the traveling power required for the hybrid vehicle is equal to or greater than the threshold value (S103). If the determination is negative, the operation stop of the internal combustion engine 1 is maintained (S104). On the other hand, if an affirmative determination is made in S103, the internal combustion engine 1 is started (S105). Specifically, the cranking of the internal combustion engine 1 is performed by the first motor generator 4, and the fuel injection and ignition in the internal combustion engine 1 are started to start the independent operation of the engine. As a result, the hybrid vehicle travels by using the second motor generator 5 and the internal combustion engine 1 together.

According to the embodiment described in detail above, the following effects can be obtained.
(1) In the high vehicle speed region during the travel of the hybrid vehicle only by driving the second motor generator 5, the threshold value used for determining whether to start the internal combustion engine 1 is intended to improve the fuel consumption of the internal combustion engine 1. The value is changed to a value (a value indicated by a two-dot chain line in FIG. 2) larger than a value (a value indicated by a broken line in FIG. 2). For this reason, when the hybrid vehicle that is running only by driving the second motor generator 5 is accelerated from the deceleration state, the output torque of the second motor generator 5 increases as the required running power increases. Since the traveling power does not easily exceed the threshold value, the internal combustion engine 1 that is stopped at that time is less likely to start. In this case, when the torque acting on the drive shaft 3 of the hybrid vehicle is reversed from the negative torque to the positive torque due to the increase in the output torque of the second motor generator 5, the period of the reversal overlaps the start of the start of the internal combustion engine 1. That is suppressed. Incidentally, since it is not necessary to discriminate the above period when suppressing the overlap of the period in which the torque acting on the drive shaft 3 is reversed and the start of the internal combustion engine 1 in this way, such a discrimination cannot be performed accurately. As a result, the above period and the start of the internal combustion engine 1 do not overlap. Then, by suppressing the overlap between the period and the start of the internal combustion engine 1, the output torque of the engine 1 is prevented from rapidly increasing with the start of the internal combustion engine 1 when the torque is reversed. A sudden increase in positive torque acting on the shaft 3 is also suppressed. Therefore, it is possible to suppress the occurrence of a shock due to a sudden increase in positive torque acting on the drive shaft 3 and the increase in rattling noise between gears that mesh with each other.

  (2) When the threshold value is variably set based on the vehicle speed so as to improve the fuel efficiency of the internal combustion engine 1, the threshold value is set based on the vehicle speed so that the threshold value decreases as the vehicle speed increases as shown by the broken line in FIG. It will be variably set. At this time, it is preferable to change the threshold value based on the vehicle speed as indicated by a two-dot chain line in FIG. 2 so that the threshold value increases as the vehicle speed increases in the high vehicle speed region. Here, as the vehicle speed increases, when the hybrid vehicle that is running only by driving the second motor generator 5 is accelerated from the decelerated state, the amount of accelerator operation tends to increase and the required running power tends to increase. . In order to make it difficult for the traveling power to become higher than the threshold even under such a tendency, it is effective to make the threshold variable according to the vehicle speed as described above. Therefore, the traveling power is less likely to become greater than or equal to the threshold through the above-described variable threshold according to the vehicle speed.

In addition, the said embodiment can also be changed as follows, for example.
In the high vehicle speed region, the threshold value increases as the vehicle speed increases. However, the threshold value does not necessarily have to be variable in such a manner. For example, the threshold value may be a constant value in the high vehicle speed region. However, the threshold value set to a constant value at this time is set to a value larger than a value intended to improve fuel consumption of the internal combustion engine 1 (value indicated by a broken line in FIG. 2).

  As a map for obtaining the threshold value, a first map that defines the relationship between the vehicle speed and the threshold value indicated by the broken line in FIG. 2, and a first map that defines the relationship between the vehicle speed and the threshold value indicated by the two-dot chain line in FIG. Two types of maps, two maps, may be prepared, and the threshold value may be obtained by referring to the first map in the low vehicle speed region, while the threshold value may be obtained by referring to the second map in the high vehicle speed region.

  The variable setting of the threshold value based on the vehicle speed can be realized by obtaining the threshold value by calculation based on the vehicle speed using a calculation formula.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Power split gear mechanism, 3 ... Drive shaft, 4 ... 1st motor generator, 5 ... 2nd motor generator, 6 ... Battery, 7 ... Inverter, 8 ... Accelerator pedal, 9 ... Accelerator position sensor, DESCRIPTION OF SYMBOLS 10 ... Vehicle speed sensor, 11 ... Wheel, 12 ... Counter gear, 13 ... Final gear, 14 ... Reduction gear mechanism, 15 ... Electronic control apparatus.

Claims (3)

A motor and an internal combustion engine are mounted as a prime mover, which is applied to a hybrid vehicle that travels by transmitting output torque of the prime mover to wheels via a gear mechanism, and the traveling power required by the vehicle is less than a threshold value In a control apparatus for a hybrid vehicle that sometimes travels only by driving the motor, and starts the engine to travel by driving the internal combustion engine when the traveling power exceeds a threshold value,
Setting means for variably setting the threshold value based on the vehicle speed in order to improve the fuel consumption of the internal combustion engine;
Changing means for changing the threshold value to a value larger than a value variably set by the setting means in a high vehicle speed region;
A control apparatus for a hybrid vehicle, comprising: The setting means variably sets the threshold based on the vehicle speed so that the threshold decreases as the vehicle speed increases.
The control device for a hybrid vehicle according to claim 1, wherein the changing means changes the threshold value based on the vehicle speed so that the threshold value becomes larger as the vehicle speed becomes higher. The setting means sets the threshold value with reference to a map based on the vehicle speed when the vehicle speed is lower than the high vehicle speed region,
When the changing means is a vehicle speed in the high vehicle speed region, it is assumed that the threshold is set by the setting means based on the vehicle speed by setting the threshold with reference to a map based on the vehicle speed. The control device for a hybrid vehicle according to claim 1, wherein the value is larger than a threshold value in the case.

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