JP2016136015A - Vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle control device which can quickly restart an engine when a restart of the engine is requested during a stop operation period of the engine.SOLUTION: A vehicle control device 6 comprises: a torque control part 61 which lowers a rotation number of an engine 2 by making an MG 3 generate torque in a negative direction when a restart of the engine 2 is requested during a stop operation period of the engine 2; and an engine control part 62 which inverts a rotation direction of the engine 2 after the lowering of the rotation number of the engine 2 by making the MG 3 generate the torque in the negative direction in a torque control part 61, and when a piston of a cylinder in an expansion stroke reaches a prescribed position, restarts the engine 2 by injecting fuel into the cylinder and igniting the fuel. When the rotation number of the engine 2 is lowered to a first rotation number or below, the torque control part 61 releases the generation of the torque in the negative direction by the MG 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle control device.

2. Description of the Related Art Conventionally, there is known an engine start control device that switches a start mode in accordance with the number of revolutions of the engine when a restart request for the engine is made during an engine stop operation period (see, for example, Patent Document 1). .
In the engine start control device described in Patent Document 1, when the engine speed is greater than or equal to a predetermined threshold value, torque is generated in the forward direction (the same direction as the engine rotation direction) by the starter motor. Restart. On the other hand, when the engine speed is less than a predetermined threshold, the engine start control device generates torque in the negative direction that prevents the engine from rotating by the starter motor, completely stops the engine, and restarts the engine. After positioning to the position, restart again.

JP 2004-124878 A

  However, in the engine start control device described in Patent Document 1, when the engine speed is less than a predetermined threshold, the engine is completely stopped before the engine is restarted, and the restart position is set. Is positioned. For this reason, there is a problem that it takes a long time to restart the engine and it cannot be restarted quickly.

  The present invention has been made in view of the above, and provides a vehicle control device capable of quickly restarting an engine when there is a request for restarting the engine during an engine stop operation period. For the purpose.

  In order to solve the above-described problems and achieve the object, a vehicle control device according to the present invention is mounted on a vehicle including an engine and a torque generation unit that generates a negative torque that prevents rotation of the engine, A vehicle control device for controlling the operation of the vehicle, wherein when the engine is requested to be restarted during a stop operation period of the engine, the torque generation unit generates the torque in the negative direction. A torque control unit for reducing the engine speed, and the torque control unit causing the torque generating unit to generate the torque in the negative direction so that the engine speed decreases and then the engine rotation direction is reversed. In addition, when the piston of the cylinder in the expansion stroke reaches a predetermined position, the engine is controlled by injecting and igniting fuel into the cylinder and restarting the engine. And a part, the torque control unit, when the rotational speed of the engine becomes a first rotational speed below and cancels the generation of the negative direction of torque by the torque generating unit.

The vehicle control device according to the present invention generates a negative torque (brake to the engine) to reduce the rotational speed of the engine when there is a restart request of the engine during the stop operation period of the engine. . Then, after the vehicle control device reduces the rotational speed of the engine, the rotational direction of the engine is reversed, and the piston of the cylinder in the expansion stroke reaches a predetermined position (for example, near the top dead center). Sometimes fuel is injected and ignited into the cylinder to restart the engine. That is, the vehicle control device restarts the engine before completely stopping the engine. For this reason, the engine can be restarted quickly.
In particular, the cylinder in the expansion stroke during the reverse rotation operation of the engine is compressed by the reverse rotation operation. For this reason, sufficient torque can be obtained by injecting and igniting the fuel into the cylinder, and the engine can be reliably restarted.
By the way, for example, when a negative torque is continuously generated even if the rotational direction of the engine is reversed, the generation of the negative torque causes the piston of the cylinder in the expansion stroke to move to a predetermined position (for example, It takes time to reach the vicinity of the top dead center).
The vehicle control device according to the present invention cancels the generation of torque in the negative direction when the rotational speed of the engine becomes equal to or lower than the first rotational speed. For this reason, as compared with the configuration in which negative torque is continuously generated, the piston of the cylinder in the expansion stroke can be made to reach a predetermined position (for example, near the top dead center) in a short time during the reverse rotation operation of the engine. it can.
From the above, the vehicle control device according to the present invention has an effect that the engine can be restarted quickly and reliably.

  In the vehicle control device according to the present invention, in the above invention, the torque control unit generates the torque in the negative direction by the torque generation unit when the rotation speed of the engine becomes 0 and the rotation direction of the engine is reversed. Is preferably released. For this reason, while shortening the time until the engine reversely rotates due to the generation of the negative direction torque, the generation of the negative direction torque is canceled when the engine speed reaches zero, thereby causing the expansion stroke. The piston of a certain cylinder can reach a predetermined position (for example, near the top dead center) in a short time.

In the vehicle control device according to the present invention, in the above invention, when the engine restart request is made during the engine stop operation period, the torque control unit is in a compression process immediately before the restart request. If the rotational speed of the engine when the piston reaches top dead center is equal to or higher than the second rotational speed, the torque generating unit generates the torque in the negative direction, and if the rotational speed is less than the second rotational speed, It is preferable not to generate the torque in the negative direction in the torque generator.
By the way, if the rotational speed of the engine is low when the piston of the cylinder in the compression process reaches top dead center immediately before the restart request, the engine may stop without performing reverse rotation.
In the vehicle control device according to the present invention, when there is an engine restart request during the engine stop operation period, the cylinder control piston in the compression process immediately before the restart request reaches the top dead center. If the engine speed is equal to or higher than the second speed, negative torque is generated. If the engine speed is lower than the second speed, negative torque is not generated. For this reason, it can prevent that an engine stops without performing reverse rotation operation, and can aim at the effect mentioned above suitably.

  According to the vehicle control device of the present invention, there is an effect that the engine can be restarted quickly when there is a request for restarting the engine during the stop operation period of the engine.

FIG. 1 is a diagram schematically showing a configuration of a vehicle according to Embodiment 1 of the present invention. FIG. 2 is a flowchart showing an example of the operation of the vehicle control device shown in FIG. FIG. 3 is a time chart showing the behavior of the engine speed and the crank angle by the operation of the vehicle control device shown in FIG. FIG. 4 is a flowchart illustrating an example of the operation of the vehicle control device according to the second embodiment of the present invention. FIG. 5 is a time chart showing the behavior of the engine speed and the crank angle by the vehicle control device shown in FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings. The present invention is not limited to the embodiments described below. Furthermore, the same code | symbol is attached | subjected to the same part in description of drawing.

(Embodiment 1)
[Schematic configuration of the vehicle]
FIG. 1 is a diagram schematically showing a configuration of a vehicle 1 according to Embodiment 1 of the present invention.
The vehicle 1 is a one-motor type hybrid vehicle, and can be switched to normal driving using a power source of an engine or a motor, or inertia driving (hereinafter referred to as free-run driving) that stops the engine and does not use the power source. To do. As shown in FIG. 1, the vehicle 1 includes an engine (ENG) 2, a motor / generator (MG) 3, a clutch 4, a stepped transmission (T / M) 5, and a vehicle control device 6. Prepare.

Under the control of the vehicle control device 6, the engine 2 converts the combustion energy of the fuel combusted in the cylinder into the rotational energy of the output shaft 2a and outputs it. In the first embodiment, the engine 2 includes a plurality of cylinders, and each cylinder is configured by a multi-cylinder engine that performs a combustion cycle including intake, compression, expansion, and exhaust strokes with a predetermined phase difference. Yes.
Here, as shown in FIG. 1, a pulley 7a is provided at one end of the output shaft 2a of the engine 2 so as to be integrally rotatable.

MG3 is a permanent magnet type AC synchronous electric motor.
Here, as shown in FIG. 1, the pulley 7b is provided in the rotating shaft of MG3 so that integral rotation is possible. Further, the pulley 7 b is connected to the pulley 7 a through the transmission belt 8. That is, the rotation shaft of MG 3 is connected to the output shaft 2 a of the engine 2 via the pulleys 7 a and 7 b and the transmission belt 8.
The MG 3 is driven via the inverter 10 according to the motor drive power supplied from the battery 9 under the control of the vehicle control device 6, and the motor torque is applied to the output shaft 2 a of the engine 2 to thereby apply the vehicle 1. As a power source. In addition, the MG 3 applies a load to the output shaft 2a of the engine 2 under the control of the vehicle control device 6 and generates negative torque (brake to the engine 2) that prevents rotation of the output shaft 2a. It also has a function as a torque generator. Furthermore, MG3 also has a function as a generator. When MG 3 functions as a generator, the generated power is stored in battery 9 via inverter 10.
As shown in FIG. 1, the rotating shaft of the MG 3 and the output shaft 2 a of the engine 2 are connected to an auxiliary machine 11 such as a power steering pump or an air conditioner compressor via pulleys 7 a to 7 c and a transmission belt 8. Are connected.

The clutch 4 is, for example, a friction engagement type clutch device, and is hydraulically controlled by the hydraulic control device 12 under the control of the vehicle control device 6 according to the operation of a clutch pedal (not shown) by the driver. Is engaged or released. Then, the clutch 4 switches to a transmission state in which engine torque is transmitted between the output shaft 2a of the engine 2 and the input shaft of the stepped transmission 5, or a cut-off state in which the engine torque is cut off.
The stepped transmission 5 has an input shaft connected to the output shaft 2 a of the engine 2 via the clutch 4, and an output shaft connected to the left and right drive wheels 14 via the differential gear 13. The stepped transmission 5 executes a shift corresponding to the shift position of the shift lever in accordance with the operation of the shift lever (not shown) by the driver. That is, in the first embodiment, the stepped transmission 5 is a manual transmission.

The vehicle control device 6 is configured by using an electronic control unit (ECU) having a computer, and controls the operation of each part of the vehicle 1 based on signals from various sensors mounted on the vehicle 1.
Here, as the various sensors, as shown in FIG. 1, an engine speed sensor 15 for detecting the speed of the crankshaft connected to the output shaft 2a of the engine 2 (hereinafter referred to as engine speed), The crank angle sensor 16 for detecting the rotational position of the crankshaft (hereinafter referred to as the crank angle), the vehicle speed sensor 17 for detecting the vehicle speed of the vehicle 1, the respective operation amounts of the accelerator pedal, the brake pedal, and the clutch pedal by the driver, respectively. Examples of the accelerator pedal sensor 18, the brake pedal sensor 19, and the clutch pedal sensor 20 that are detected can be given.
Hereinafter, the main part of the present invention will be mainly described as the configuration (function) of the vehicle control device 6. In FIG. 1, only the main part of the present invention is illustrated as the configuration of the vehicle control device 6.

[Configuration of vehicle control device]
As shown in FIG. 1, the vehicle control device 6 includes a torque control unit 61 and an engine control unit 62.
The torque control unit 61 short-circuits the switching element in the inverter 10 when the vehicle 1 is in free-running and there is a request to restart the engine 2 during the stop operation period of the engine 2. Due to the short circuit of the switching element, a reflux current flows in the MG 3 and a load is applied to the output shaft 2 a of the engine 2. That is, the torque control unit 61 causes the MG 3 to function as the torque generation unit according to the present invention in the above case.
Note that a technique for applying a load to the output shaft 2a of the engine 2 by a short circuit of the switching element in the inverter 10 is a known technique (see, for example, JP 2012-202407 A).

Here, free-running means that the respective operation amounts of the accelerator pedal, the brake pedal, and the clutch pedal detected by the sensors 17 to 19 when the vehicle 1 is running are less than a predetermined threshold value (each This means that the vehicle 1 is set to the following state at the time when the pedal is not depressed (OFF) (when the engine 2 is requested to stop).
Specifically, the vehicle control device 6 switches the clutch 4 to the disengaged state via the hydraulic control device 12 when recognizing that each pedal is OFF. As a result, the connection between the engine 2 and the stepped transmission 5 is released, and the power transmission from the power source is cut off and the drive wheels 14 become free. Further, the vehicle control device 6 stops the injection and ignition of the fuel in each cylinder of the engine 2 to stop the engine 2.
The stop operation period of the engine 2 is a state in which fuel injection and ignition in each cylinder of the engine 2 are stopped after the engine 2 is requested to stop, and the engine speed is reduced.

The restart request for the engine 2 is recognized at the following time.
Specifically, the torque control unit 61 determines whether any of the operation amounts of the accelerator pedal, the brake pedal, or the clutch pedal detected by the sensors 17 to 19 during the stop operation period of the engine 2 is a predetermined threshold value. When the above is reached (when any of the pedals is depressed (ON)), it is recognized that a restart request for the engine 2 has been made.

The torque control unit 61 cancels the generation of torque in the negative direction by the MG 3 when the engine speed detected by the engine speed sensor 15 is equal to or lower than the first speed (first threshold). To do.
In the first embodiment, the torque control unit 61 cancels the generation of torque in the negative direction by the MG 3 when the engine speed detected by the engine speed sensor 15 becomes “0”. That is, in the first embodiment, the first rotational speed described above is “0”.

The engine control unit 62 causes the torque control unit 61 to generate a negative torque in the MG 3, so that the rotation speed of the output shaft 2 a of the engine 2 is reversed. When the piston of the cylinder in the expansion stroke among the cylinders reaches a predetermined position (in the first embodiment, near the top dead center), fuel injection and ignition in the cylinder are started and the engine 2 is restarted. Let
Here, when the engine speed detected by the engine speed sensor 15 shifts from positive to negative, the engine control unit 62 reverses the rotation direction of the output shaft 2a of the engine 2 (from the normal rotation direction to the reverse rotation direction). Recognizing that Further, the engine control unit 62 recognizes that the piston of the cylinder in the above-described expansion stroke has reached the vicinity of the top dead center based on the crank angle detected by the crank angle sensor 16.

[Operation of vehicle control device]
Next, the operation of the vehicle control device 6 described above will be described.
In the following, the operation in which the vehicle 1 is switched from the normal travel to the free-run travel and the engine 2 is restarted during the stop operation period of the engine 2 will be mainly described. The control flow shown below is repeatedly executed at predetermined time intervals during the stop operation period of the engine 2 when the vehicle 1 is switched to free-running.
FIG. 2 is a flowchart showing an example of the operation of the vehicle control device 6.
First, the torque control unit 61 determines whether or not there is a restart request for the engine 2 (step S1).

When it is determined that there is no restart request for the engine 2 (step S1: No), the vehicle control device 6 causes the crank angle when the engine 2 is completely stopped to be a target stop crank angle suitable for starting. Then, stop position control is performed (step S2). Thereafter, the vehicle control device 6 ends this control flow.
Specifically, the vehicle control device 6 calculates the rotational behavior of the output shaft 2a of the engine 2 (hereinafter referred to as a target trajectory) until the crank angle of the engine 2 stops at the target stop crank angle. The vehicle control device 6 performs stop position control for controlling the load applied to the rotation shaft 2a of the engine 2 by the MG 3 so that the rotation behavior of the output shaft 2a of the engine 2 (the behavior of the engine speed) follows the target trajectory. Run.
The stop position control is a known technique (see, for example, JP 2008-215230 A).
On the other hand, when it is determined that the restart request for the engine 2 has been made (step S1: Yes), the torque control unit 61 is detected by the engine speed sensor 15 when the restart request for the engine 2 is made. It is determined whether or not the engine speed is equal to or lower than a third speed (third threshold value) (step S3).

When it is determined that the engine speed exceeds the third speed (step S3: No), the vehicle control device 6 determines the engine 2 based on the crank angle detected by the crank angle sensor 16. Of each cylinder, the fuel in the cylinder in the compression process is injected and ignited, and the engine 2 is restarted (returning independently) (step S4). Thereafter, the vehicle control device 6 ends this control flow.
On the other hand, when it is determined that the engine speed is equal to or lower than the third speed (step S3: Yes), the torque control unit 61 causes the MG3 to generate negative torque (step S5).

After step S5, the vehicle control device 6 (the torque control unit 61 and the engine control unit 62) reverses the rotation direction of the output shaft 2a of the engine 2 (the engine speed detected by the engine speed sensor 15 is normal). Whether or not it has shifted from negative to negative (becomes equal to or lower than the first rotation speed “0”) is constantly monitored (step S6).
When it is determined that the rotation direction of the output shaft 2a of the engine 2 has been reversed (step S6: Yes), the torque control unit 61 cancels the generation of torque in the negative direction by the MG 3 (step S7).

After step S7, based on the crank angle detected by the crank angle sensor 16, the engine control unit 62 determines whether the piston of the cylinder in the expansion stroke among the cylinders of the engine 2 has reached near the top dead center. Is constantly monitored (step S8). That is, in step S8, the engine control unit 62 always monitors whether or not the piston of the cylinder in the expansion stroke has reached the vicinity of the top dead center “first”.
When it is determined that the piston of the cylinder in the expansion stroke has reached the vicinity of the top dead center (step S8: Yes), the engine control unit 62 starts the fuel injection and ignition in the cylinder to start the engine 2. Restart (step S9). Thereafter, the vehicle control device 6 ends this control flow.

[Specific example of engine speed and crank angle behavior]
Next, the behavior of the engine speed and the crank angle by the operation of the vehicle control device 6 shown in FIG. 2 will be described with reference to FIG.
FIG. 3 is a time chart showing the behavior of the engine speed and the crank angle by the operation of the vehicle control device 6 shown in FIG.
In FIG. 3, a timing T <b> 1 indicates a timing at which the vehicle 1 is switched from the normal traveling to the free-run traveling and the stop operation period of the engine 2 is started.
When the stop operation period of the engine 2 starts (timing T1), the output shaft 2a of the engine 2 rotates by inertia. Therefore, after the timing T1, the engine speed gradually decreases as shown in FIG. More specifically, the engine speed temporarily drops every time the piston of each cylinder of the engine 2 reaches the top dead center (timing T2 to T4 shown in FIG. 3), and increases when it exceeds the top dead center. In such a form, for every predetermined crank angle, it decreases while repeating up and down.

Here, in FIG. 3, the timing T <b> 5 indicates the timing when the restart request for the engine 2 is made. FIG. 3 shows a case where the engine speed at the timing T5 is the third speed used for the determination in step S3 for convenience of explanation.
When there is a restart request of the engine 2 at the timing T5 (step S1: Yes), the engine speed is equal to or lower than the third speed (step S3: Yes). At this timing T5, a negative torque is generated in MG3 (step S5).
That is, when there is a restart request of the engine 2 between the timing T1 and the timing T5 (step S1: Yes), the engine speed exceeds the third speed (step S3: No). The vehicle control device 6 performs fuel injection and ignition in the cylinder in the compression process, and restarts the engine 2 (returns independently) (step S4).

After timing T5, the engine speed is further decreased as shown in FIG. 3 by generating a negative torque in MG3. Then, after the timing T4 when the piston of the cylinder in the compression process exceeds the top dead center, the piston of the cylinder in the next compression process cannot exceed the top dead center. That is, the piston of the cylinder that has entered the compression process but could not exceed the top dead center is pushed back by the compression reaction force due to the air pressure in the cylinder. For this reason, at the timing T6, the rotation direction of the output shaft 2a of the engine 2 is reversed.
Then, at the timing T6 when the rotation direction of the output shaft 2a of the engine 2 is reversed, the torque control unit 61 releases the generation of torque in the negative direction by the MG 3 (step S7).

After timing T6, the piston of the cylinder in the expansion stroke (cylinder that has finally reached the expansion stroke beyond the top dead center) is directed toward the top dead center because the rotation direction of the output shaft 2a of the engine 2 is reversed. Will rise. Then, at the timing T7 when the piston of the cylinder in the expansion stroke reaches near the top dead center, the engine control unit 62 starts fuel injection and ignition in the cylinder and restarts the engine 2 (step S9). .
That is, when the rotation direction of the output shaft 2a of the engine 2 is reversed and the air pressure in the cylinder in the expansion stroke is increased, the fuel injection and ignition in the cylinder are started, whereby the engine 2 The engine 2 is restarted by applying as much forward torque as possible to the output shaft 2a.
Here, the vicinity of the top dead center is preferably in the range of 0 ° to 60 ° when the crank angle when the piston of the cylinder in the expansion stroke reaches the top dead center is 0 °.
In FIG. 3, for convenience of explanation, the behavior of the engine speed and crank angle after timing T7 shows the behavior in a state where the engine 2 is not restarted at timing T7.

  Here, the alternate long and short dash line shown in FIG. 3 shows the behavior of the engine speed and the crank angle when the generation of torque in the negative direction by MG3 is continued after timing T6, unlike the first embodiment. Yes. In this way, when generation of negative torque by MG3 continues after timing T6, the piston of the cylinder in the expansion stroke reaches near the top dead center by the action of the negative torque (see FIG. 3). It will take time until the indicated timing T8).

The vehicle control device 6 according to the first embodiment described above causes the MG 3 to generate a torque in the negative direction and generate the engine speed when the engine 2 is requested to restart during the stop operation period of the engine 2. Reduce. Then, the vehicle control device 6 reduces the rotational speed of the engine 2 and then reverses the rotational direction of the output shaft 2a of the engine 2 and when the piston of the cylinder in the expansion stroke reaches near the top dead center. Then, the fuel is injected and ignited in the cylinder to restart the engine 2. That is, the vehicle control device 6 restarts the engine 2 before stopping the engine 2 completely. For this reason, the engine 2 can be restarted quickly.
In particular, the cylinder in the expansion stroke during the reverse rotation of the engine 2 (when the rotation direction of the output shaft 2a of the engine 2 is reversed) is compressed by the reverse rotation. For this reason, sufficient torque can be obtained by injecting and igniting fuel into the cylinder, and the engine 2 can be reliably restarted.
By the way, for example, when a negative torque is continuously generated in the MG 3 even when the rotation direction of the engine 2 is reversed, as shown by a one-dot chain line in FIG. It takes time until the piston of the cylinder in the expansion stroke reaches near the top dead center.
On the other hand, the vehicle control device 6 according to the first embodiment cancels the generation of torque in the negative direction by the MG 3 when the engine speed becomes zero. For this reason, compared with the configuration in which the negative torque is continuously generated in MG3, the negative torque generated by MG3 is reduced while the time until the engine 2 is reversely rotated due to the negative torque generated by MG3 is shortened. By canceling the occurrence of this, the piston of the cylinder in the expansion stroke can reach the vicinity of the top dead center in a short time.
From the above, the vehicle control device 6 according to the first embodiment has an effect that the engine 2 can be restarted quickly and reliably.

(Embodiment 2)
Next, a second embodiment of the present invention will be described.
In the following description, the same reference numerals are given to the same configurations and steps as those in the above-described first embodiment, and the detailed description thereof is omitted or simplified.
The vehicle control device 6 according to the first embodiment described above causes the MG 3 to generate negative torque when the engine speed when the engine 2 is requested to restart is equal to or lower than the third speed. It was.
On the other hand, the vehicle control device according to the second embodiment satisfies other conditions in addition to the condition that the engine speed is equal to or lower than the third speed when the engine 2 is requested to be restarted. When it is satisfied, MG3 generates a torque in the negative direction.
And the structure of the vehicle which concerns on this Embodiment 2 is the structure similar to Embodiment 1 mentioned above.
Below, only operation | movement of the vehicle control apparatus 6 which concerns on this Embodiment 2 is demonstrated.

[Operation of vehicle control device]
FIG. 4 is a flowchart showing an example of the operation of the vehicle control device 6 according to Embodiment 2 of the present invention.
As shown in FIG. 4, the operation of the vehicle control device 6 according to the second embodiment is different from the operation of the vehicle control device 6 described in the first embodiment (FIG. 2) instead of step S6. Steps S6A and S6B are added, and only steps S10 to S13 are added. Therefore, only steps S10 to S13, S6A, and S6B will be described below.

Step S10 is executed when it is determined in step S3 that the engine speed is equal to or lower than the third speed (step S3: Yes).
Specifically, in step S10, the torque control unit 61 has the engine speed at the top dead center immediately before the time when the restart request for the engine 2 is requested is equal to or higher than the second speed (second threshold). Determine whether or not.
Here, the engine speed at the top dead center means the engine speed detected by the engine speed sensor 15 each time the piston of each cylinder of the engine 2 reaches the top dead center. The engine speed at the top dead center is sequentially stored in a memory (not shown). That is, in step S10, the torque control unit 61 determines that the latest engine speed at the top dead center stored in a memory (not shown) (the engine rotation at the top dead center immediately before the restart of the engine 2 is requested). Number) is recognized, and it is determined whether or not the engine speed is equal to or higher than the second speed.

When it is determined that the engine speed at the top dead center immediately before is less than the second speed (step S10: No), the vehicle control device 6 proceeds to step S6B.
On the other hand, if it is determined that the engine speed at the top dead center immediately before is greater than or equal to the second speed (step S10: Yes), the vehicle control device 6 proceeds to step S5 and returns to MG3 in the negative direction. Torque is generated.

Step S11 is executed after step S5.
Specifically, the torque control unit 61 determines that the piston of any cylinder (cylinder in the compression process) of the engine 2 is at the top dead center based on the crank angle detected by the crank angle sensor 16 in step S11. Always monitor whether it has been reached.
When it is determined that the piston has reached the top dead center (step S11: Yes), the torque control unit 61 detects the engine speed detected by the engine speed sensor 15 when the top dead center is reached. It is determined whether or not the number is equal to or greater than a second rotation number (same as the second rotation number used in the determination in step S10) (step S12).

When it is determined that the engine speed is equal to or higher than the second speed (step S12: Yes), the vehicle control device 6 proceeds to step S6A.
On the other hand, when it is determined that the engine rotational speed is less than the second rotational speed (step S12: No), the torque control unit 61 cancels generation of torque in the negative direction by MG3 (step S13). Thereafter, the vehicle control device 6 proceeds to Step S6B.

In step S6A, the vehicle control device 6 determines whether or not the rotation direction of the output shaft 2a of the engine 2 has been reversed in substantially the same manner as in step S6 described in the first embodiment.
When it is determined that the rotation direction of the output shaft 2a of the engine 2 is not reversed (step S6A: No), the vehicle control device 6 returns to step S11.
On the other hand, when it is determined that the rotation direction of the output shaft 2a of the engine 2 has been reversed (step S6A: Yes), the vehicle control device 6 proceeds to step S7 and cancels the generation of torque in the negative direction by the MG3. .

In step S6B, the vehicle control device 6 constantly monitors whether or not the rotation direction of the output shaft 2a of the engine 2 has been reversed, as in step S6 described in the first embodiment.
When it is determined that the rotation direction of the output shaft 2a of the engine 2 has been reversed (step S6B: Yes), the vehicle control device 6 proceeds to step S8, and the piston of the cylinder in the expansion stroke is at top dead center. It always monitors whether it has reached the vicinity.

[Specific example of engine speed and crank angle behavior]
Next, the behavior of the engine speed and the crank angle by the operation of the vehicle control device 6 shown in FIG. 4 will be described with reference to FIG.
FIG. 5 is a time chart showing the behavior of the engine speed and the crank angle by the operation of the vehicle control device 6 shown in FIG.
Here, the timings T1 to T4 shown in FIG. 5 are the same as the timings T1 to T4 shown in FIG. The behavior of the engine speed and crank angle from timing T1 to T4 indicated by the solid line in FIG. 5 is the same as the behavior of engine speed and crank angle from timing T1 to T4 indicated by the solid line in FIG. . Further, the timings T6 and T7 shown in FIG. 5 are the same as the timings T6 and T7 shown in FIG. 3, and the timing at which the rotation direction of the output shaft 2a of the engine 2 is reversed and the piston of the cylinder in the expansion stroke is increased. The timing at which the vicinity of the dead center is reached (timing for restarting the engine 2) is shown. In FIG. 5, for convenience of explanation, the behaviors of the engine speed and the crank angle after the timing T <b> 7 show behaviors when the engine 2 is not restarted.

  In FIG. 5, for convenience of explanation, the timing T4 is the timing when the piston reaches top dead center immediately before the time point when the restart of the engine 2 used for the determination in step S10 is requested, or the determination in step S11. The timing at which the piston of any cylinder (cylinder in the compression process) of the engine 2 used in FIG. FIG. 5 shows the case where the engine speed at the timing T4 is less than the second speed (step S10: No, step S12: No).

5 is different from the second embodiment in that the engine speed at the timing T4 is less than the second speed (step S10: No, step S12: No). First, when the process proceeds to step S5 and MG3 generates a negative torque, or the process proceeds to step S13 (release of generation of negative torque by MG3) and the process proceeds to step S6A and the negative torque is generated by MG3. The behavior of the engine speed and crank angle when the generation of torque in the direction is continued is shown.
Even if the engine speed is relatively low (less than the second speed), MG3 generates negative torque or MG3 continues to generate negative torque 5, the output shaft 2a of the engine 2 stops rotating without reversing the direction of rotation thereof, as indicated by a one-dot chain line in FIG. That is, it is impossible to restart the engine 2 by starting fuel injection and ignition in the cylinder in the expansion stroke in step S9.
Therefore, in the second embodiment, when the engine speed is a relatively low engine speed (less than the second engine speed) (step S10: No, step S12: No), step S5 (negative by MG3). The process proceeds to step S6B without shifting to (generation of torque in the direction), or shifts to step S13 to cancel the generation of torque in the negative direction by MG3. Therefore, as shown by the solid line in FIG. 5, the rotation direction of the output shaft 2a of the engine 2 is reversed, and in step S9, the injection and ignition of the fuel in the cylinder in the expansion stroke is started and the engine 2 is started. Can be restarted.
Therefore, according to the vehicle control device 6 according to the second embodiment, it is possible to prevent the engine from stopping without performing the reverse rotation operation, and to appropriately achieve the same effect as the first embodiment described above. it can.

(Other embodiments)
The embodiments for carrying out the present invention have been described so far, but the present invention should not be limited only by the above-described first and second embodiments.
The vehicle 1 described in the first and second embodiments described above employs the clutch 4 and the manual transmission (stepped transmission 5). However, the present invention is not limited to this, and the clutch 4 is omitted. Instead, an automatic transmission (a stepped transmission or a continuously variable transmission) may be adopted.

  In the first and second embodiments described above, MG3 is employed as the torque generating unit according to the present invention. However, the present invention is not limited to this, and a load is applied to output shaft 2a of engine 2 to prevent rotation of output shaft 2a. Other configurations may be adopted as long as the configuration generates negative torque.

  The torque control unit 61 described in the first and second embodiments described above cancels the generation of the negative torque by the MG3 when the engine speed becomes zero after the MG3 generates the negative torque. However, the present invention is not limited to this, and if the engine speed is equal to or lower than the predetermined speed, the negative torque generated by MG3 before the engine speed becomes zero or after the engine speed becomes zero. You may cancel the occurrence.

  The control flow is not limited to the processing order in the flowcharts described in the first and second embodiments, and may be changed within a consistent range.

1 vehicle 2 engine 3 MG (torque generator)
6 Vehicle control device 61 Torque control unit 62 Engine control unit

Claims (3)

A vehicle control device that is mounted on a vehicle including an engine and a torque generation unit that generates torque in a negative direction that prevents rotation of the engine, and controls the operation of the vehicle,
A torque control unit that reduces the engine speed by causing the torque generation unit to generate the torque in the negative direction when there is a request to restart the engine during the stop operation period of the engine;
The torque control unit causes the torque generation unit to generate the torque in the negative direction, so that the rotation speed of the engine decreases, and then the piston of the cylinder in the expansion stroke is reversed. An engine control unit that, when reaching a predetermined position, injects and ignites fuel into the cylinder and restarts the engine;
The torque control unit
The vehicle control device, wherein the generation of the torque in the negative direction by the torque generator is canceled when the engine speed is equal to or lower than the first speed. The torque control unit
2. The vehicle control device according to claim 1, wherein the generation of the torque in the negative direction by the torque generation unit is canceled when the rotation speed of the engine becomes 0 and the rotation direction of the engine is reversed. The torque control unit
When there is a restart request for the engine during the stop operation period of the engine, the engine speed when the piston of the cylinder in the compression process reaches top dead center immediately before the restart request is second. The negative torque is generated in the torque generator when the rotational speed is equal to or higher than the second rotational speed, and the negative torque is not generated in the torque generator when the rotational speed is less than the second rotational speed. Item 3. The vehicle control device according to Item 1 or 2.

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