JP2007246010A - Controller for hybrid electric car - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the controller of a hybrid electric car for maintaining satisfactory driving performance of a vehicle by transmitting proper driving force or braking force to a driving wheel, even when a failure occurs in a motor output system. <P>SOLUTION: This controller of a hybrid electric car is provided with an engine output system for making an engine 2 generate and output driving force and a motor output system for making a motor 6 generate and output driving force, and the driving force output by each system can be transmitted to a driving wheel 16. A speed change map, to be used when the failure of the motor output system is detected among speed change maps for controlling an automatic transmission 8 for transmitting the driving force of the engine 2 to be output from the engine output system to the driving wheel 16, is configured so that downshift can be performed relatively early, and upshift can be performed later, according to the change in the driving conditions of a vehicle, in comparison with the speed change map to be used, when failure of the motor output system is not detected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for a hybrid electric vehicle, and more particularly to a control device for a hybrid electric vehicle capable of transmitting an engine driving force and an electric motor driving force to driving wheels of a vehicle.

Conventionally, an engine and an electric motor are mounted on a vehicle, and an engine output system that generates and outputs driving force to the engine and an electric motor output system that generates and outputs driving force to the motor are output from both systems. A so-called parallel type hybrid electric vehicle has been developed and put into practical use, which can transmit the driving force to be transmitted to the driving wheels of the vehicle.
As such a parallel type hybrid electric vehicle, a clutch for mechanically connecting and disconnecting an engine and an automatic transmission is provided, and a rotating shaft of an electric motor is connected between an output shaft of the clutch and an input shaft of the automatic transmission. For example, Patent Document 1 proposes.

In a hybrid electric vehicle as disclosed in Patent Document 1, the clutch is disengaged when starting the vehicle, the motor is operated by supplying power from the battery, and the vehicle is started only by the driving force of the motor. During traveling, the clutch is connected so that the driving force of the engine and the driving force of the electric motor can be transmitted to the driving wheels via the transmission.
When it is possible to drive the vehicle using both the driving force of the engine and the driving force of the electric motor in this way, the torque necessary for driving the vehicle is appropriately distributed between the engine and the electric motor, and the distributed torque is obtained. The vehicle travels by transmitting the driving force of the engine and the driving force of the motor operated by the motor to the driving wheels via the transmission. At this time, the gear position of the automatic transmission and the clutch engagement / disengagement state are appropriately controlled according to the running state of the vehicle.

In addition, when the vehicle decelerates, the electric motor is operated to generate a regenerative braking force to obtain a braking force necessary to decelerate the vehicle, and energy is recovered by converting the braking energy into electric power and charging the battery. I am doing so.
JP-A-5-176405

In such a hybrid electric vehicle, when a failure occurs in an electric motor, an inverter, or a battery constituting the electric motor output system, power supply from the battery to the electric motor is cut off, and the engine driving force output by the engine output system It is conceivable that the vehicle travels only with this.
However, in this case, since the driving force of the electric motor output from the electric motor output system cannot be used, the driving force transmitted to the driving wheels is insufficient, and good vehicle running performance cannot be ensured. There is a problem.

Further, since the regenerative braking force by the motor output system cannot be used even when the vehicle is decelerated, there is a problem that the braking force transmitted to the drive wheels is insufficient and the vehicle cannot be decelerated properly. .
The present invention has been made in view of such problems, and an object of the present invention is to ensure that proper driving force and braking force are transmitted to the drive wheels even when a failure occurs in the motor output system. Another object of the present invention is to provide a control apparatus for a hybrid electric vehicle capable of maintaining good vehicle driving performance.

  In order to achieve the above object, a control apparatus for a hybrid electric vehicle according to the present invention includes an engine output system that generates a driving force in an engine and outputs the driving force of the engine, and a motor driving force that generates the driving force of the motor. And a motor output system that outputs a driving force, wherein the driving force output from each system can be transmitted to driving wheels of the vehicle. An automatic transmission that transmits the driving force of the engine output from the system to the drive wheels, a failure detection means that detects a failure of the motor output system, and a change in the driving state of the vehicle based on a predetermined shift map. Accordingly, the shift stage of the automatic transmission is controlled to be switched, and a failure of the motor output system is detected by the failure detection means. In this case, a downshift corresponding to a change in the driving state of the vehicle is performed earlier than the shift map used when no failure of the motor output system is detected by the failure detection means, and the vehicle And a control means for controlling the automatic transmission using a shift map in which an upshift according to a change in the driving state is performed late.

  According to the hybrid electric vehicle control device configured as described above, when the motor output system is normal, the engine driving force output from the engine output system and the motor driving force output from the motor output system are Can be transmitted to the drive wheels and the vehicle travels, and the automatic transmission is appropriately shifted up and down in accordance with changes in the driving state of the vehicle.

  On the other hand, when a failure is detected in the motor output system, the automatic transmission is downshifted earlier in response to a change in the driving state of the vehicle, compared to when no failure is detected in the motor output system. The shift is performed late, and the driving force of the engine output from the engine output system is transmitted to the drive wheels via the automatic transmission.

  The hybrid electric vehicle control apparatus further includes a clutch capable of interrupting a driving force transmitted from the engine output system to the automatic transmission, and a rotation speed detection means for detecting the rotation speed of the electric motor. If the failure is not detected by the failure detection means during deceleration of the vehicle, the control means sets an upper limit deceleration as a regenerative braking torque that can be generated by the electric motor according to the rotation speed detected by the rotation speed detection means. In addition to setting a torque, a required deceleration torque is set as a deceleration torque necessary for the deceleration of the vehicle. When the required deceleration torque is equal to or less than the upper limit deceleration torque, the clutch is disconnected to generate the required deceleration torque. The required output torque is greater than the upper limit deceleration torque. In this case, the engine output system and the motor output system are controlled by connecting the clutch so that the sum of the deceleration torque from the engine and the regenerative braking torque from the electric motor becomes the required deceleration torque, If the failure is detected by the failure detection means during deceleration of the vehicle, the clutch is always connected at least until the engine speed decreases to near the idle speed. ).

  According to the control apparatus for a hybrid electric vehicle configured as described above, when the motor output system is normal, the upper limit deceleration as the regenerative braking torque that can be generated by the motor according to the rotation speed of the motor when the vehicle decelerates. Set the torque and set the required deceleration torque as the deceleration torque required for vehicle deceleration. If the required deceleration torque is below the upper limit deceleration torque, the clutch is disconnected and the required deceleration torque is transmitted only by the motor output system. On the other hand, when the requested deceleration torque is larger than the upper limit deceleration torque, the engine output system and the electric motor are connected so that the sum of the deceleration torque from the engine and the regenerative braking torque from the electric motor becomes the requested deceleration torque when the clutch is connected. The output system is controlled.

  On the other hand, when a failure is detected in the motor output system, the clutch is always connected at least until the engine speed decreases to near the idle speed when the vehicle is decelerated.

  According to the control apparatus for a hybrid electric vehicle of the present invention, when a failure is detected in the motor output system, the automatic transmission according to a change in the driving state of the vehicle is compared with a case where no failure is detected in the motor output system. Because the downshift of the motor is performed early and the upshift is performed late, the drive required for driving the vehicle is possible even when the motor drive power cannot be obtained due to the failure of the motor output system. It is possible to ensure the power, maintain good running performance, and prevent the driving feeling from being lowered due to insufficient driving force.

  In addition, even when the vehicle is decelerating, if a failure is detected in the motor output system, the automatic transmission is downshifted early according to changes in the vehicle operating state. Even if it is not possible to obtain the vehicle, the vehicle can be appropriately decelerated by the braking force of the engine output system obtained through the shift stage shifted down early.

  Further, when no failure is detected in the motor output system, the engine driving force output from the engine output system can be used in combination with the engine driving force output from the engine output system. It is possible to shift up early compared to an automatic transmission of a vehicle that uses only the drive source. As a result, when the vehicle is driven using both the engine output system and the motor output system, the fuel efficiency of the engine can be improved while obtaining the driving force necessary for driving the vehicle.

  According to the control apparatus for a hybrid electric vehicle of claim 2, when a failure is detected in the motor output system, at least until the engine speed decreases to near the idle speed when the vehicle decelerates. Since the clutch is always connected, the braking force from the engine output system can be continuously transmitted to the drive wheels, and the vehicle can be decelerated appropriately.

  FIG. 1 is a block diagram of a main part of a control device for a hybrid electric vehicle 1 according to an embodiment of the present invention. An input shaft of a clutch 4 is connected to an output shaft of a diesel engine (hereinafter referred to as an engine) 2, and the output shaft of the clutch 4 is moved forward via a rotating shaft of a permanent magnet type synchronous motor (hereinafter referred to as an electric motor) 6. An input shaft of an automatic transmission (hereinafter referred to as “transmission”) 8 having five speeds (hereinafter simply referred to as “shift speed”) is connected. The output shaft of the transmission 8 is connected to the left and right drive wheels 16 via a propeller shaft 10, a differential device 12 and a drive shaft 14.

Therefore, when the clutch 4 is connected, both the output shaft of the engine 2 and the rotating shaft of the electric motor 6 can be mechanically connected to the drive wheels 16 via the transmission 8, and the clutch 4 is disconnected. Sometimes only the rotating shaft of the electric motor 6 can be mechanically connected to the drive wheels 16 via the transmission 8.
The electric motor 6 operates as a motor when the DC power stored in the battery 18 is converted into AC power by the inverter 20 and supplied thereto, and after the driving torque is shifted to an appropriate speed by the transmission 8, the driving wheel is driven. 16 is transmitted. Further, when the vehicle is decelerated, the electric motor 6 operates as a generator, and kinetic energy generated by the rotation of the drive wheels 16 is transmitted to the electric motor 6 through the transmission 8 and converted into AC power, thereby generating regenerative braking torque. Then, the AC power is converted into DC power by the inverter 20, and then charged in the battery 18. The kinetic energy generated by the rotation of the drive wheels 16 is recovered as electric energy.

  On the other hand, the drive torque of the engine 2 is transmitted to the transmission 8 via the rotating shaft of the electric motor 6 when the clutch 4 is connected, and is transmitted to the drive wheels 16 after being shifted to an appropriate speed. It has become. Therefore, when the electric motor 6 operates as a motor when the driving torque of the engine 2 is transmitted to the driving wheels 16, the driving torque of the engine 2 and the driving torque of the electric motor 6 are respectively driven via the transmission 8. It will be transmitted to the wheel 16. That is, a part of the drive torque to be transmitted to the drive wheels 16 for driving the vehicle is supplied from the engine 2 and the remaining part is supplied from the electric motor 6.

When the charging rate (hereinafter referred to as SOC) of the battery 18 decreases and the battery 18 needs to be charged, the electric motor 6 operates as a generator, and the electric motor 6 is turned on using a part of the driving force of the engine 2. Power generation is performed by driving, and the generated AC power is converted into DC power by the inverter 20 and then the battery 18 is charged.
The vehicle ECU 22 (control means) performs connection / disconnection control of the clutch 4 and gear stage switching control of the transmission 8 in accordance with the operation state of the vehicle and the engine 2 and information from the engine ECU 24, the inverter ECU 26, and the battery ECU 28. At the same time, integrated control for appropriately driving the engine 2 and the electric motor 6 is performed in accordance with these control states and various driving states such as start, acceleration, and deceleration of the vehicle.

  When the vehicle ECU 22 performs such control, the accelerator opening sensor 32 that detects the depression amount of the accelerator pedal 30, the vehicle speed sensor 34 that detects the traveling speed of the vehicle, and the rotation that detects the rotation speed of the electric motor 6. Based on the detection result of the number sensor (rotational speed detection means) 36, the total driving torque required for traveling of the vehicle and the total deceleration torque required for deceleration of the vehicle are calculated, and the engine 2 is calculated from these total driving torque and total deceleration torque. And the torque generated by the electric motor 6 are set.

The engine ECU 24 performs various controls necessary for the operation of the engine 2 such as start / stop control of the engine 2, idle control, or regeneration control of an exhaust gas purification device (not shown), and the engine set by the vehicle ECU 22 The fuel injection amount and injection timing of the engine 2 are controlled so that the engine 2 generates the torque required for the engine 2.
On the other hand, the inverter ECU 26 controls the operation of the motor 6 by operating the motor 6 or the generator by controlling the inverter 20 based on the torque that should be generated by the motor 6 set by the vehicle ECU 22. In addition to receiving an output signal from a temperature sensor (not shown) that detects the temperature of the electric motor 6 and the inverter 20, the temperature of the electric motor 6 is sent to the vehicle ECU 22, and the operating state of the electric motor 6 and the inverter 20 is monitored. The information is sent to the vehicle ECU 22.

The battery ECU 28 detects the temperature of the battery 18, the voltage of the battery 18, the current flowing between the inverter 20 and the battery 18, obtains the SOC of the battery 18 from these detection results, and operates the battery 18. Is monitoring. Then, the obtained SOC and the operating state of the battery 18 are sent to the vehicle ECU 22 together with the detection result.
The hybrid electric vehicle 1 is configured as described above. The engine 2 and the engine ECU 24 constitute an engine output system, and the electric motor 6, the battery 18, the inverter 20, the inverter ECU 26, and the battery ECU 28 constitute an electric motor output system. Yes.

In the hybrid electric vehicle 1 configured as described above, an outline of control performed mainly by the vehicle ECU 22 in order to drive the vehicle is as follows.
First, when the vehicle is stopped and the engine 2 is stopped, and the change lever (not shown) is in the neutral position, the driver performs an operation of starting the engine 2 with a starter switch (not shown). The vehicle ECU 22 confirms that the transmission 8 is in the neutral position and that the mechanical connection between the electric motor 6 and the drive wheel 16 is cut off and the clutch 4 is connected, and then the inverter ECU 26 The drive torque of the electric motor 6 necessary for starting the engine 2 is instructed, and the engine ECU 24 is instructed to operate the engine 2.

Based on an instruction from the vehicle ECU 22, the inverter ECU 26 operates the motor 6 to generate drive torque, cranks the engine 2, and the engine ECU 24 starts supplying fuel to the engine 2, thereby starting the engine 2. Then idle driving.
In this state, when the driver operates the change lever to the drive position or the like, the vehicle ECU 22 disengages the clutch 4 and sets the shift stage of the transmission 8 to the shift stage at the start of start according to the shift map. When the driver depresses the accelerator pedal 30, the vehicle ECU 22 obtains a driving torque to be transmitted to the driving wheels 16 in order to start the vehicle according to the depression amount of the accelerator pedal 30 detected by the accelerator opening sensor 32. The output torque of the electric motor 6 is set on the basis of this driving torque and the gear stage being used in the transmission 8.

  The inverter ECU 26 controls the inverter 20 according to the output torque of the electric motor 6 set by the vehicle ECU 22, and the DC power of the battery 18 is converted into AC power by the inverter 20 and supplied to the electric motor 6. The electric motor 6 is actuated by the supply of AC power to generate a driving force, and the driving force of the electric motor 6 is transmitted to the driving wheels 16 via the transmission 8 to start the vehicle.

  When the vehicle starts to accelerate and the rotational speed of the electric motor 6 rises to the vicinity of the idle rotational speed of the engine 2, the clutch 4 can be connected to transmit the driving force of the engine 2 to the drive wheels, and the vehicle ECU 22 further The driving torque to be transmitted to the driving wheels 16 is determined for the acceleration of the vehicle and the subsequent driving. The drive torque is appropriately distributed between the output torque of the engine 2 and the output torque of the electric motor 6 according to the gear stage being used in the transmission 8, the driving state of the vehicle, etc., and the engine ECU 24 and the inverter ECU 26 are instructed. The transmission 8 and the clutch 4 are controlled as necessary.

  The engine ECU 24 and the inverter ECU 26 receive the output torque set by the vehicle ECU 22 to control the engine 2 and the electric motor 6, respectively. When the clutch 4 is connected, the output torque of the engine 2 and the electric motor 6 is transmitted via the transmission 8. While being transmitted to the drive wheels 16, the output torque generated by the electric motor 6 is transmitted to the drive wheels 16 via the transmission 8 when the clutch 4 is disengaged, and the vehicle travels.

  Further, at this time, the vehicle ECU 22 appropriately changes the gear position of the transmission 8 according to the driving state of the vehicle such as the depression amount of the accelerator pedal 30 detected by the accelerator opening sensor 32 and the traveling speed detected by the vehicle speed sensor 34. In addition to switching control, the engine ECU 24 and the inverter ECU 26 are instructed to control the torque of the engine 2 and the electric motor 6 appropriately in accordance with the switching of the shift speed, and the connection / disconnection of the clutch 4 is controlled.

  Meanwhile, the vehicle ECU 22 monitors whether or not a failure has occurred in the motor output system based on information sent from the inverter ECU 26 and the battery ECU 28. The failure of the motor output system includes a failure of an inverter circuit (not shown) used in the inverter 20 and a failure of a cell in the battery 18, and when such a failure occurs in the motor output system. The vehicle ECU 22 instructs the inverter ECU 26 to cut off the electrical connection between the battery 18 and the inverter 20. Inverter ECU 26 controls inverter 20 in accordance with this instruction, and disconnects the electrical connection between battery 18 and inverter 20.

When the electrical connection between the battery 18 and the inverter 20 is thus cut off, the electric motor 6 does not operate as either a motor or a generator, and the driving force of the engine 2 when the clutch 4 is connected. To rotate with the engine 2.
When the electric motor 6 stops operating, it becomes impossible to transmit the driving force from the electric motor output system to the driving wheel 16. Even in such a case, the necessary driving force is transmitted to the driving wheel 16. Therefore, the vehicle ECU 22 switches the shift map used when performing the shift speed control of the transmission 8 according to the driving state of the vehicle depending on whether or not the motor output system is broken.

The shift map switching control by the vehicle ECU 22 is performed at a predetermined control cycle according to the flowchart shown in FIG.
When the shift map switching control is started, it is determined in step S1 whether or not a failure has occurred in the motor output system based on information from the inverter ECU 26 and the battery ECU 28 (failure detection means).

  If it is determined in step S1 that the motor output system has not failed, that is, the motor output system is normal, the process proceeds to step S2 to select the shift-up shift map SU1 and the shift-down shift map SD1. If it is determined that a failure has occurred in the motor output system, the process proceeds to step S3, where the shift-up shift map SU2 and the shift-down shift map SD2 are selected, and the control cycle ends.

In this way, by repeating the determination in step S1 for each control cycle, a combination of shift-up shift map SU1 and shift-down shift map SD1 or a shift is appropriately performed depending on whether or not a failure has occurred in the motor output system. A combination of the upshift map SU2 and the downshift map SD2 is selected.
These shift maps shift up and down the shift stage of the transmission 8 according to the depression amount of the accelerator pedal 30 detected by the accelerator opening sensor 32 and the travel speed detected by the vehicle speed sensor 34. Used when.

FIG. 3 shows a shift-up shift map SU1 that is selected when the motor output system is normal among these shift maps. From the second speed according to the depression amount of the accelerator pedal 30 and the traveling speed, FIG. A shift up line to 3rd speed (2 → 3), a shift up line from 3rd speed to 4th speed (3 → 4) and a shift up line from 4th speed to 5th speed (4 → 5) are set.
Therefore, when the point determined by the depression amount of the accelerator pedal 30 and the traveling speed crosses the shift-up line from the second speed to the third speed from the left to the right in the figure, the vehicle ECU 22 changes the transmission. Shift up the 8th gear from 2nd gear to 3rd gear. The same applies to the upshift line from the 3rd speed to the 4th speed and the upshift line from the 4th speed to the 5th speed, and the points determined by the depression amount of the accelerator pedal 30 and the traveling speed are shown in the figure. A corresponding upshift occurs when crossing from left to right.

  This shift-up shift map SU1 is used in combination with the shift map of an automatic transmission that is applied to a vehicle that uses only the engine as a drive source without mounting the motor because the output torque of the motor 6 is used together. Therefore, the shift up is performed early. As a result, when the vehicle is driven by using the engine 2 and the electric motor 6 in combination, the fuel efficiency of the engine 2 can be improved while obtaining a driving force necessary for driving the vehicle.

Further, as shown in FIG. 3, when the motor output system is normal, the lowest gear position is the second speed, and when the vehicle starts, the vehicle starts starting with the second gear position.
On the other hand, FIG. 4 shows a shift-up shift map SU2 that is selected when a failure is detected in the motor output system. Depending on the amount of depression of the accelerator pedal 30 and the traveling speed, the first to second shift maps are shown. Shift-up line to 1st speed (1 → 2) Shift-up line from 2nd to 3rd speed (2 → 3) Shift-up line from 3rd speed to 4th speed (3 → 4) and 4th speed to 5th speed Shift-up lines (4 → 5) are set as indicated by solid lines in the figure.

  Even when this map is used, the upshift is performed in the same manner as in the upshift map SU1, but as shown in FIG. 4, the upshift map SU2 includes the upshift map SU1. There is no upshift line from 1st to 2nd. That is, when a failure occurs in the motor output system, the lowest gear is set to the first speed, and when the vehicle is started, the vehicle is started with the gear set as the first speed.

  Further, in the drawing, each shift-up line of the shift-up shift map SU1 is indicated by a dotted line. In contrast to these shift-up lines, the corresponding shift-up lines of the shift-up shift map SU2 are all the same accelerator pedal 30. Upshifting is performed at a higher speed with respect to the amount of stepping on. That is, when the shift-up shift map SU2 is used, the shift-up according to the change in the driving state of the vehicle is performed later than when the shift-up shift map SU1 is used.

FIG. 5 shows a shift-down shift map SD1 that is selected when the motor output system is normal. A shift-down line from the fifth speed to the fourth speed according to the depression amount of the accelerator pedal 30 and the traveling speed. (4 ← 5) A downshift line (3 ← 4) from the fourth speed to the third speed and a downshift line (2 ← 3) from the third speed to the second speed are set.
Therefore, when the point determined by the depression amount of the accelerator pedal 30 and the traveling speed crosses the downshift line from the 5th speed to the 4th speed from the right side to the left side in the figure, the vehicle ECU 22 changes the transmission. Shift down the 8th gear from 5th gear to 4th gear. The same applies to the downshift line from the 4th speed to the 3rd speed and the downshift line from the 3rd speed to the 2nd speed. The points determined by the amount of depression of the accelerator pedal 30 and the traveling speed indicate the respective downshift lines. A corresponding downshift occurs when crossing from right to left.

Further, when the motor output system is normal, the downshift is performed only up to the second speed as shown in FIG. 5, and as described above, the start of the vehicle is started with the second gear position when the next vehicle starts. .
On the other hand, FIG. 6 shows a shift-down shift map SD2 that is selected when a failure occurs in the motor output system. Depending on the depression amount of the accelerator pedal 30 and the traveling speed, the fifth to fourth speeds are shown. Downshift line (4 ← 5) downshift line from 4th gear to 3rd gear (3 ← 4) downshift line from 3rd gear to 2nd gear (2 ← 3) and 2nd gear to 1st gear The downshift line (1 ← 2) is set as indicated by the solid line in the figure.

  Even when this map is used, the downshift is performed in the same manner as in the downshift map SD1, but as shown in FIG. 6, the downshift map SD2 includes the downshift map SD1. There is no shift down line from 2nd gear to 1st gear. Therefore, when a failure occurs in the motor output system, downshifting is performed to the first speed as the traveling speed decreases, and as described above, when the next vehicle starts, the vehicle starts starting with the first gear position. .

  In the drawing, each downshift line of the downshift map SD1 is indicated by a dotted line, but the corresponding downshift line of the downshift map SD2 is the same accelerator pedal 30 with respect to these upshift lines. The shift down is performed at a higher speed with respect to the amount of stepping on. That is, when the downshift map SD2 is used, the downshift according to the change in the driving state of the vehicle is performed earlier than when the downshift map SD1 is used.

By selecting and using each shift map set in this way, the driving force is transmitted to the drive wheels 16 as follows.
When the motor output system is normal and the shift-up shift map SU1 and the shift-down shift map SD1 are selected by the shift map switching control, the driver starts the vehicle as described above. The vehicle ECU 22 disengages the clutch 4 and sets the speed of the transmission 8 to the second speed according to the selected shift map. Then, the output torque of the electric motor 6 when the shift speed is the second speed is set from the driving torque to be transmitted to the driving wheel 16 set by the vehicle ECU 22 according to the depression amount of the accelerator pedal 30, and the set driving of the electric motor 6 is set. The inverter ECU 26 controls the inverter 20 according to the torque, whereby the driving force of the electric motor 6 is transmitted to the driving wheels 16 through the transmission 8 and the vehicle starts.

As described above, when the motor output system is normal, the vehicle is started by the electric motor 6 with the speed of the transmission 8 set to the second speed, so that the vehicle can be started smoothly.
When the vehicle starts to accelerate and the rotational speed of the electric motor 6 rises to the vicinity of the idle rotational speed of the engine 2, the clutch 4 can be connected to transmit the driving force of the engine 2 to the drive wheels, and the vehicle ECU 22 further The driving torque to be transmitted to the driving wheels 16 is determined for the acceleration of the vehicle and the subsequent driving. Then, a required torque to be output from the engine 2 and the electric motor 6 is obtained from the drive torque according to the gear stage being used in the transmission 8, and the required torque is obtained from the engine 2 side and the electric motor 6 side according to the driving state of the vehicle. Appropriately.

  Further, when the vehicle travels in this way, the vehicle ECU 22 determines the depression amount of the accelerator pedal 30 and the vehicle speed detected by the accelerator opening sensor 32 based on the selected shift-up shift map SU1 and shift-down shift map SD1. The shift stage of the transmission 8 is shifted up or down according to the change in the traveling speed detected by the sensor 34, and the clutch 4 is controlled as necessary.

That is, when the point determined by the amount of depression of the accelerator pedal 30 and the traveling speed crosses the shift-up line of the shift-up shift map SU1 shown in FIG. 3 as described above, the upshift is performed, and the downshift shown in FIG. A downshift is performed when crossing the downshift line of the shift map SD1.
Therefore, when the vehicle starts and accelerates, the speed of the transmission 8 is sequentially shifted up as the traveling speed increases, but the speed at the time of starting the vehicle is 2nd as described above. As a result, smooth acceleration can be performed by reducing the number of upshifts up to the fifth speed compared to the case where the shift stage at the start is the first speed.

On the other hand, when a failure is detected in the motor output system and the shift-up shift map SU2 and the shift-down shift map SD2 are selected by the shift map switching control, the driver starts the vehicle as described above. When this is done, the vehicle ECU 22 disengages the clutch 4 and sets the gear position of the transmission 8 to the first speed according to the selected shift map.
At this time, since the electric motor 6 does not operate, the vehicle ECU 22 instructs the engine ECU 24 to output a torque corresponding to the depression amount of the accelerator pedal 30 from the engine 2 and controls the clutch 4 by half clutch. In response to an instruction from the vehicle ECU 22, the engine ECU 24 controls the engine 2 to output torque corresponding to the amount of depression of the accelerator pedal 30 detected by the accelerator opening sensor 32 and the rotational speed of the engine 2. The driving force of the engine 2 is transmitted to the drive wheels 16 via the transmission 8 via the clutch 4 in the clutch state, whereby the vehicle starts.

Although no driving force is transmitted from the electric motor 6 to the driving wheel 16, the gear stage used in the transmission 8 at this time is the first speed, and therefore the driving force necessary for starting the vehicle is transmitted to the driving wheel 16. Therefore, it is possible to prevent a decrease in driving performance and driving feeling due to insufficient driving force when starting the vehicle.
When the vehicle starts and accelerates, the rotational speed of the electric motor 6 rises to near the idle rotational speed of the engine 2 and the clutch 4 is completely connected, the vehicle ECU 22 drives the drive wheels 16 for further acceleration of the vehicle and subsequent travel. The driving torque to be transmitted to is determined. Then, a required torque to be output from the engine 2 is obtained from the drive torque in accordance with the gear stage being used in the transmission 8, and the engine ECU 24 is instructed to output the required torque by the engine 2.

Further, the vehicle ECU 22 responds to changes in the amount of depression of the accelerator pedal 30 detected by the accelerator opening sensor 32 and changes in travel speed detected by the vehicle speed sensor 34 based on the selected shift-up shift map SU2 and shift-down shift map SD2. Thus, the gear stage of the transmission 8 is shifted up or down, and the clutch 4 is controlled as necessary.
That is, when the point determined by the amount of depression of the accelerator pedal 30 and the traveling speed crosses the shift-up line of the shift-up shift map SU2 shown in FIG. 4 as described above, the shift-up is performed, and the shift-down shown in FIG. A downshift is performed when crossing the downshift line of the shift map SD2.

  At this time, the shift-up shift map SU2 and the shift-down shift map SD2 are slower than the shift-up shift map SU1 and the shift-down shift map SD1 with respect to changes in the depression amount and travel speed of the accelerator pedal 30. For this reason, a shift up is performed and a shift down is performed early. Accordingly, even if the driving force 16 is not obtained from the electric motor 6 and the driving wheels 16 are driven only by the driving force of the engine 2, the driving force does not become insufficient. A decrease can be prevented.

The vehicle ECU 22 performs switching control of the shift map as described above depending on whether or not a failure has occurred in the motor output system, and also the clutch 4 when the depression of the accelerator pedal 30 is released and the vehicle decelerates. Control is also switched.
In other words, when the vehicle decelerates, as described above, the vehicle can be appropriately decelerated by the regenerative braking force of the electric motor 6. However, when a failure occurs in the motor output system, such a regenerative braking force should be used. Therefore, by switching the control of the clutch 2, proper deceleration is performed even when a failure occurs in the motor output system.

The switching control of the clutch control by the vehicle ECU 22 is performed at a predetermined control cycle according to the flowchart shown in FIG.
When the clutch control switching control is started, whether or not a failure has occurred in the motor output system based on the information from the inverter ECU 26 and the battery ECU 28 in step S11 as in step S1 of the shift map switching control in FIG. (Failure detection means).

If it is determined in step S11 that the motor output system has not failed, that is, the motor output system is normal, the process proceeds to step S12 to select the clutch control A, while the motor output system has failed. When it determines, it progresses to step S13, the clutch control B is selected, and the control period is complete | finished.
Thus, by repeating the determination in step S11 for each control cycle, the clutch control A or the clutch control B is selected depending on whether or not a failure has occurred in the motor output system.

The vehicle ECU 22 controls the engine 2 and the electric motor 6 as follows in addition to the clutch control selected in this manner when the vehicle is decelerated.
When the depression of the accelerator pedal 30 is released when the motor output system is normal, the vehicle ECU 22 determines the speed of the motor 6 detected by the speed sensor 36 and the gear stage being used in the transmission 8. A deceleration torque necessary for appropriately decelerating the vehicle is set as a required deceleration torque.

The required deceleration torque is individually set for each gear stage of the transmission 8 as indicated by a solid line in FIG. 8, and the required deceleration torque corresponding to each gear stage increases as the rotational speed of the electric motor 6 increases. It has the characteristic to do. In addition, as shown in FIG. 8, a larger required deceleration torque is set for a higher speed gear.
Further, the vehicle ECU 22 sets the upper limit value of the regenerative braking torque that can be generated by the electric motor 6 at the rotational speed of the electric motor 6 detected by the rotational speed sensor 36 as the upper limit deceleration torque. This upper limit deceleration torque is determined according to the rotational speed of the electric motor 6 according to the specifications of the electric motor 6, and has a constant value in the low rotational speed region, as shown by a dashed line in FIG. However, the motor 6 has such a characteristic that it decreases as the rotational speed of the motor 6 increases. Further, as shown in FIG. 8, the magnitude relationship of the upper limit deceleration torque is reversed at each rotation speed of N2 to N5 with respect to the required deceleration torque set corresponding to each of the second to fifth gears.

When the requested deceleration torque is larger than the upper limit deceleration torque, the requested deceleration torque cannot be obtained only by the regenerative braking torque of the electric motor 6. The required deceleration torque is obtained together with the deceleration torque due to regenerative braking of the electric motor 6.
Further, when the required deceleration torque is equal to or less than the upper limit deceleration torque, the required deceleration torque can be obtained only by the regenerative braking torque of the electric motor 6, so that the required deceleration torque can be obtained only by the regenerative braking of the electric motor 6 by cutting the clutch 4. obtain.

By performing control in this way, energy recovery during deceleration is performed using regenerative braking of the electric motor 6 as much as possible. Therefore, in the clutch control A selected when the motor output system is normal, the connection / disconnection state of the clutch 4 is controlled according to the magnitude relationship between the required deceleration torque and the upper limit deceleration torque.
On the other hand, when a failure is detected in the motor output system, if the depression of the accelerator pedal 30 is released, the regenerative braking force by the motor 6 cannot be obtained, so the vehicle ECU 22 puts the clutch 4 in a connected state, The engine ECU 24 is instructed to perform the deceleration operation of the engine 2 such as stopping the fuel supply or operating the exhaust brake when the exhaust brake is provided.

The engine ECU 24 performs the deceleration operation of the engine 2 by stopping the fuel supply or operating the exhaust brake if it has an exhaust brake in accordance with an instruction from the vehicle ECU 22.
As a result, the deceleration torque of the engine 2 is transmitted from the transmission 8 to the drive wheels 16 via the clutch 4, whereby the vehicle is decelerated. The rotational speed detected by the rotational speed sensor 36 at this time coincides with the rotational speed of the engine 2 because the clutch 4 is connected, but the traveling speed decreases as the vehicle decelerates, and is detected by the rotational speed sensor 36. When it is detected that the rotational speed of the engine 2 has decreased to the vicinity of the idle rotational speed based on the rotational speed, the vehicle ECU 22 disengages the clutch 4 so that the rotational speed of the engine 2 does not decrease below the idle rotational speed.

Thus, in the clutch control B that is selected when a failure is detected in the motor output system, the clutch 4 is always connected until the rotational speed of the engine 2 decreases to the vicinity of the idle rotation, and the deceleration torque of the engine 2 The vehicle is decelerated.
As a result, even when a failure occurs in the motor output system and the regenerative braking force of the motor 6 cannot be used, the use of the shift down shift map SD2 in which the early downshift is performed as described above is combined. Thus, the deceleration torque required for proper deceleration of the vehicle can be continuously transmitted to the drive wheels 16, and the vehicle can be decelerated satisfactorily.

Although the description of the control apparatus for a hybrid electric vehicle according to one embodiment of the present invention is finished above, the present invention is not limited to the above embodiment.
For example, in the above embodiment, the gear stage at the start of the vehicle when a failure is detected in the motor output system is set to the first speed, and the gear stage at the start of the vehicle when the motor output system is normal is set to the second speed. The gear stage at the time of vehicle start in each case is not limited to this, and the gear stage at the time of vehicle start is set according to the specification of the vehicle, and the motor output is higher than the gear stage when the motor output system is normal. What is necessary is just to make it the speed stage when a failure is detected in the system be on the low speed side.

  Furthermore, in the above embodiment, the electric motor 6 is arranged between the clutch 4 and the transmission 8. However, the arrangement of the electric motor 6 is not limited to this, and for example, between the engine 2 and the clutch 4. Similar effects can be obtained as long as the hybrid electric vehicle can transmit the driving force of the engine 2 and the driving force of the electric motor 6 to the drive wheels 16 such as a hybrid electric vehicle in which the electric motor 6 is disposed.

In the above embodiment, the transmission 8 is an automatic transmission with five forward speeds. However, the number of shift speeds and the type of automatic transmission are not limited to this, and may be a continuously variable transmission or the like. .
Furthermore, in the above embodiment, the rotation speed of the electric motor 6 detected by the rotation speed sensor 36 is used. However, the output rotation speed of the transmission 8 is detected and converted into the rotation speed of the electric motor 6 using the gear ratio. Alternatively, the rotational speed of the electric motor 6 may be obtained from an amount that changes according to the rotational speed of the electric motor 6.

  In the above embodiment, the engine 2 is a diesel engine, but the engine type is not limited to this, and a gasoline engine or the like may be used.

1 is an overall configuration diagram of a hybrid electric vehicle according to an embodiment of the present invention. 3 is a flowchart of shift map switching control performed by the hybrid electric vehicle control device of FIG. 1. FIG. 6 is a diagram showing a shift-up shift map SU1. FIG. 6 is a diagram showing a shift-up shift map SU2. It is a figure which shows shift map SD1 for a downshift. It is a figure which shows shift map SD2 for a downshift. FIG. 2 is a flowchart of clutch control switching control performed by the hybrid electric vehicle control device of FIG. 1. FIG. It is a figure which shows the relationship between the upper limit deceleration torque of an electric motor, and a request | requirement deceleration torque.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hybrid electric vehicle 2 Engine 4 Clutch 6 Electric motor 8 Automatic transmission 16 Drive wheel 18 Battery 20 Inverter 22 Vehicle ECU (failure detection means, control means)
26 Inverter ECU
28 Battery ECU
36 Rotational speed sensor (Rotational speed detection means)

Claims (2)

An engine output system that generates driving force in the engine and outputs the driving force of the engine, and a motor output system that generates driving force in the motor and outputs the driving force of the motor, are output from the respective systems. In a control apparatus for a hybrid electric vehicle that can transmit the drive force to the drive wheels of the vehicle,
An automatic transmission having a plurality of forward shift stages and transmitting the driving force of the engine output from the engine output system to the driving wheels;
A failure detection means for detecting a failure of the motor output system;
Based on a predetermined shift map, the shift stage of the automatic transmission is switch-controlled according to a change in the driving state of the vehicle, and when a failure of the motor output system is detected by the failure detection means, the failure detection means Compared with the shift map used when no failure of the motor output system is detected, a downshift is performed earlier according to a change in the driving state of the vehicle, and an increase according to a change in the driving state of the vehicle is performed. A control device for a hybrid electric vehicle, comprising: a control unit that controls the automatic transmission using a shift map in which shifting is performed late. A clutch capable of interrupting a driving force transmitted from the engine output system to the automatic transmission;
A rotation speed detecting means for detecting the rotation speed of the electric motor;
If the failure is not detected by the failure detection means during deceleration of the vehicle, the control means sets an upper limit deceleration as a regenerative braking torque that can be generated by the electric motor according to the rotation speed detected by the rotation speed detection means. In addition to setting a torque, a required deceleration torque is set as a deceleration torque necessary for the deceleration of the vehicle. When the required deceleration torque is equal to or less than the upper limit deceleration torque, the clutch is disconnected to generate the required deceleration torque. When the required deceleration torque is greater than the upper limit deceleration torque, the clutch is connected and the sum of the deceleration torque from the engine and the regenerative braking torque from the motor is Controlling the engine output system and the motor output system to be torque, 2. If the failure is detected by the failure detection means during deceleration of the vehicle, the clutch is always connected at least until the engine speed decreases to near the idle speed. The control apparatus of the hybrid electric vehicle described in 1.

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