JP2003293816A - Controlling device for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve power performance upon starting a vehicle. <P>SOLUTION: The controlling device applied to a hybrid vehicle having an automatic engine stopping and restarting function has a first clutch 4 positioned between the engine 1 and a motor 2, and a second clutch 5 positioned between the motor 2 and driving wheels 11. Upon starting the vehicle accompanied by the automatic restart of the engine 1, the first clutch 4 is in a substantially connected state and the second clutch 5 is in a substantially disconnected state. The engine 1 is rotated and driven by the motor 2, and when the rotation number of the engine 1 reaches a predetermined number, the engine 1 is ignited. After the engine 1 is ignited, the vehicle is started by having the motor 2 assist an engine torque in a half connected state of the predetermined connected state of the first clutch 4 and increasing the connection of the second clutch 5. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a hybrid vehicle.

[0002]

2. Description of the Related Art In a hybrid vehicle in which a clutch having a power source composed of an engine and an electric motor and transmitting and cutting off the power, and an engine and an electric motor are coaxially coupled, the clutch is the electric motor and the gear shift. When the vehicle is started, when the vehicle is started, it is necessary to disengage the clutch and raise the engine speed with an electric motor to a speed at which the engine can ignite. After the engine is ignited, the engine itself generates power to keep the engine speed further increasing, and by gradually engaging the clutch, the power is transmitted to the vehicle and a smooth start is possible. Further, when the required driving force of the vehicle is larger than the engine torque that can be generated by the engine at this time, the electric motor can assist.

[0003]

However, when a motor having a small output is mounted on a vehicle as an electric motor, the rotation speed at which the electric motor can produce the maximum torque is limited to a low rotation speed. In the hybrid vehicle configuration described above, the electric motor rotates synchronously with the engine. Therefore, when the engine speed increases to a speed at which the engine can be ignited, the electric motor cannot output the maximum torque, which improves the power performance. There is a problem not to do.

[0004]

Therefore, the invention according to claim 1 is provided with a drive source comprising an engine and a motor,
Control applied to a hybrid vehicle that automatically stops the engine if a predetermined condition is satisfied when the vehicle is stopped, and automatically restarts the engine to start the vehicle if another predetermined condition is satisfied while the engine is automatically stopped. A device, a first clutch arranged between the engine and the motor, a second clutch arranged between the motor and a drive wheel of a vehicle, and an engine for detecting a rotational speed of the engine. A hybrid vehicle having a rotation speed detecting means, the engine and the rotation shaft of the motor are connected via the first clutch, and the motor and the drive wheels are connected via the second clutch. In the control device applied to, when the vehicle is started with the automatic restart of the engine, the first clutch is substantially engaged and the second clutch is substantially disengaged. The engine is rotated by the motor, the engine ignites the engine reaches the predetermined rotational speed, after ignition of the engine, the first
The vehicle is started by increasing the engagement force of the second clutch while assisting the engine torque by the motor with the clutch in a predetermined half engagement state. As a result, the rotational speed of the motor after engine ignition can be reduced.

According to a second aspect of the invention, in the first aspect of the invention, when the first clutch is brought into a predetermined half-engaged state, the engagement force of the first clutch is determined by the rotational speed of the motor. It is characterized in that it is controlled to a predetermined low rotation speed.

According to a third aspect of the present invention, in the second aspect of the invention, the predetermined low rotation speed is in a rotation speed region close to a high torque region of the motor.

According to a fourth aspect of the present invention, in the first aspect of the invention, when the first clutch is brought into a predetermined semi-engaged state, the engagement force of the first clutch is the torque of the first clutch. It is characterized in that the transmissibility is controlled so as to reach a predetermined target value. The clutch can obtain a high torque transmission rate up to a certain input / output speed difference. Thus, the torque transmitted from the engine to the drive wheels is not significantly impaired by controlling the engaging force of the first clutch so that the torque transmission rate becomes a predetermined target value.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, when the engine is started in a predetermined semi-engaged state, the engine is in a predetermined high load state. It is characterized in that it is performed only when.

According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, a reverse torque is generated in the motor when the first clutch is brought into a predetermined half-engaged state. Is characterized by. by this,
The rotation speed of the motor decreases rapidly.

[0010]

According to the present invention, since the driving torque of the motor after engine ignition is increased by lowering the rotation speed of the motor after engine ignition, the driving force of the engine and the motor is maximized. It is possible to use the motor, and it is possible to improve the acceleration performance of the vehicle even if a motor with a small output is used.

According to the sixth aspect of the present invention, the rotation speed of the motor is rapidly reduced, so that the time for sliding the first clutch is shortened, and the thermal durability of the first clutch is improved. It is possible to reduce the transmission torque loss of one clutch.

[0012]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a system configuration of a drive system of a hybrid vehicle to which the present invention is applied.

This hybrid vehicle is provided with an engine 1 and a motor generator 2 (hereinafter referred to as a motor) as drive sources, and a transmission 3 for transmitting the power of the engine 1 and the motor 2 to drive wheels.

A first clutch 4 is arranged between the engine 1 and the motor 2, and a second clutch 4 is arranged between the motor 2 and the transmission 3.
The clutch 5 is arranged. More specifically, the engine rotating shaft 6 is connected to the motor rotating shaft 7 via the first clutch 4, and the motor rotating shaft 7 is connected to the input side rotating shaft 8 of the transmission 3 via the second clutch 5. Has been done. The output side rotation shaft 9 of the transmission 3 is connected to the drive wheels 11, 11 via a final reduction gear device 10.

The disengagement of the first clutch 4 and the second clutch 5 is controlled by an engine control unit 12 (hereinafter referred to as ECU) according to the operating state of the vehicle. A signal from a vehicle speed detection device 13 that detects the vehicle speed of the vehicle and a signal from an accelerator opening detection device 14 that detects the depression amount of the accelerator pedal are input to the ECU 12.

Further, the engine rotation shaft 6, the motor rotation shaft 7, and the input side rotation shaft 8 of the transmission 3 respectively have rotation speed sensors 15, 16, 17 for measuring the rotation speed of each rotation shaft.
The output signals from the sensors 15, 16 and 17 are also input to the ECU 12.

The motor 2 is a small motor having a small maximum output, and as shown in FIG.
It has a motor characteristic that the maximum torque is obtained at (rpm) and the motor torque gradually decreases in a higher rotational speed range (320 rpm or more).

The first clutch 4 and the second clutch 5 are controlled to be opened / closed by the ECU 12 in accordance with the driving state of the vehicle. For example, when the vehicle is stopped, the first clutch 4 is engaged while the engine 1 is operating. Then, by opening the second clutch 5, the motor 2 can generate electric power. When the engine runs, the first clutch 4 and the second clutch
By engaging with the clutch 5, the power of the motor 2 in addition to the power of the engine 1 can be transmitted to the drive wheels 11, 11. When the motor runs, the first clutch 4 is disengaged and the second clutch 5 is engaged, so that the engine 1
The power of the motor 2 can be transmitted to the drive wheels 11 and 11 without being affected by the friction.

Output signals from other than the various sensors shown in FIG. 1 are input to the ECU 12, and so-called idle stop control such as automatic engine stop and automatic restart is also performed based on these information. .

For example, when the selector lever of the transmission 3 is in the D range, the brake pedal is depressed by the driver, the vehicle speed is 0 (km / h), and the opening / closing devices such as the door and bonnet are all closed, the engine is closed. When the engine is burning, the accelerator is OFF, the brake is ON, the amount of charge of the battery (battery SOC) is a predetermined value or more, the negative pressure of the brake negative pressure booster is a predetermined value or more, the engine water temperature is a predetermined value or more, the transmission oil When a predetermined condition such that the temperature is a predetermined value or more and the hydraulic pressure of the transmission 3 is a predetermined value or more, the engine 1 is automatically stopped. The selector lever of the transmission 3 is in the D range, the brake pedal is depressed by the driver, the vehicle speed is 0 (km / h), and the opening and closing devices such as the door and bonnet are all closed. Inside, accelerator ON, brake OFF, battery charge amount below a predetermined value (battery SOC decrease), brake negative pressure booster negative pressure below a predetermined value, engine water temperature below a predetermined value, transmission 3 oil temperature below a predetermined value. When any of the predetermined conditions such as below the value is detected, the engine 1 is automatically restarted.

In the hybrid vehicle constructed as described above, the first clutch 4 and the second clutch 5 are used when the vehicle is in the idle stop state, that is, when the engine 1 is automatically stopped and the engine is automatically restarted. The open / close control will be described.

[0023] The start accompanied by the automatic restart of the engine causes a heavy load.
In the case of advance, as shown in FIGS. 3 to 5, the second clutch 5
Is released (input / output speed ratio R2 = 0 of the second clutch 5)
The first clutch 4 is engaged in the state (input / output of the first clutch 4
Speed ratio R1 = 1) (t = t ₀), By motor 2
The rotation speed at which the gin rotation speed can be ignited (50 in this embodiment)
0 rpm) and ignite the engine 1 (t =
t₁).

When the engine 1 ignites, the first clutch 4
To reduce the engagement force of the first clutch 4 to a predetermined semi-engaged state (half-clutch state).
Gradually increase the fastening force of. In detail, engine 1
When is ignited, the input / output speed ratio R1 of the first clutch 4 is decreased so that the input / output speed ratio R1 becomes a predetermined target value P,
The first clutch 4 is brought into a predetermined half-engaged state, and the input / output speed ratio R2 of the second clutch 5 is gradually increased.

Here, the input / output speed ratio R1 is the engine speed.
Number of rotations N of rolling shaft 6_{1 in}And the rotation speed N of the motor rotating shaft 7_{1 out}
And R1 = (N_{1 out}/ N
_{1 in}). And the input / output speed ratio R2 is
Number of rotations N of the rotary shaft 7_{2 in}And rotation of the input side rotary shaft 8 of the transmission 3.
Number of turns N_{2 out}And R2 = (N
_{2 out}/ N_{2 in}). N_{1 out}And N_{2 in}Is the motor rotation axis
Since the number of rotations is 7, the values are the same.

The clutch characteristics of the first clutch 4 and the second clutch 5 are as shown in FIG. 6, and the target value P of the input / output speed ratio R1 of the first clutch 4 is the first clutch 4
Is set to a position where the torque transmission rate of is close to 100% (half clutch state).

As described above, when the engaging force of the first clutch 4 (input / output speed ratio R1) is reduced and the engaging force of the second clutch 5 (input / output speed ratio R2) is gradually increased, the engine rotating shaft 6 is rotated. And a rotation speed difference occurs between the motor rotation shaft 7 and the input side rotation shaft 8 of the transmission 3. That is, the engine speed> the motor speed> the rotation speed of the input side rotating shaft, and the motor speed decreases with respect to the engine speed after engine ignition (t ₁ <t <t ₃ ).

When the engagement force (input / output speed ratio R2) of the second clutch 5 increases and the difference in rotational speed between the motor rotating shaft 7 and the input side rotating shaft 8 of the transmission 3 disappears, the second clutch 5 is released. Fasten (t = t ₃ ). When the second clutch 5 is engaged, the engaging force (input / output speed ratio R1) of the first clutch 4 in a predetermined semi-engaged state is gradually increased (t ₄ <t <t ₅ ),
When there is no difference in the number of revolutions between the engine rotary shaft 6 and the motor rotary shaft 7, the first clutch 4 is engaged (t = t ₅ ).

It should be noted that the determination as to whether or not the high load start is
It is determined whether the vehicle speed is below the specified value, the accelerator opening is above the specified value, and the engine speed is below the specified value.

On the other hand, when the start accompanied by the automatic engine restart is other than the high load start, the first clutch 4 is engaged with the second clutch 5 opened, and the motor 2 raises the engine 1 to a predetermined rotational speed. After that, the engine 1 is ignited, and after the engine is ignited, the second clutch 5 is gradually engaged while the first clutch 4 is engaged to drive the drive wheels 11, 1.
Power is transmitted to 1.

7 and 8 are flowcharts showing the flow of control at the time of starting a high load accompanied by automatic engine restart.

In step 1, it is determined whether or not there is an acceleration request. If there is an acceleration request, the process proceeds to step 2, and if there is no acceleration request, the process ends.

In step 2, it is determined whether the engine is stopped, that is, whether the engine 1 is in the ignited state. If the engine is stopped, the process proceeds to step 3 in which the engine is operating, that is, the engine 1 is ignited. If so, go to step 10.

In step 3, it is judged whether or not the first clutch 4 is engaged. If the first clutch 4 is engaged, the process proceeds to step 5. If the first clutch 4 is released, the process proceeds to step 4 and the first clutch 4
After concluding, proceed to step 5.

In step 5, it is judged whether or not the second clutch 5 is disengaged. If the second clutch 5 is disengaged, the process proceeds to step 7. When the second clutch 5 is engaged, the routine proceeds to step 6, where after the second clutch 5 is released, the routine proceeds to step 7.

In step 7, it is judged whether or not the engine speed has reached a speed at which the engine 1 can be ignited.
When the engine speed reaches the ignitable speed, the process proceeds to step 8 to ignite the engine 1 and then step 1
Go to 0. If the engine speed has not reached the ignitable speed, the process proceeds to step 9, the torque of the motor 2 is increased, and the process ends.

In step 10, the engine 1 and the motor torque are controlled according to the acceleration request. In step 11, it is determined whether the accelerator opening is larger than a predetermined value, that is, the acceleration request in step 1 is a high load start request, and if the accelerator opening is smaller than the predetermined value, the process proceeds to step 12 and the accelerator is opened. When the opening degree is larger than the predetermined value, the process proceeds to step 15 (after step 15 is shown in FIG. 8).

In step 12, it is determined whether the input / output speed ratio R2 of the second clutch 5 is greater than or equal to a predetermined engagement propriety determination value, and if the input / output speed ratio R2 is greater than or equal to the predetermined engagement propriety determination value. Proceeds to step 13 to engage and end the second clutch 5, and if the input / output speed ratio R2 is less than the predetermined engagement propriety determination value, proceeds to step 14
The fastening force is increased to finish.

In step 15, it is determined whether the input / output speed ratio R2 is greater than or equal to a predetermined engagement possibility determination value. When the input / output speed ratio R2 is greater than or equal to the predetermined engagement possibility determination value,
Proceed to step 16, the second clutch 5 is engaged, and proceed to step 17.

In step 17, the input / output speed ratio R1 of the first clutch 4 is compared with the target value P to determine the input / output speed ratio R1.
Is less than or equal to the target value P, the process proceeds to step 18, and if the input / output speed ratio R1 is greater than the target value P, step 19 is performed.
Then, the engaging force of the first clutch 4 is reduced and the process ends.

In step 18, it is determined whether the input / output speed ratio R1 is equal to or more than a predetermined engagement possibility determination value. When the input / output speed ratio R1 is greater than or equal to the predetermined engagement possibility determination value,
Proceeding to step 20, the first clutch 4 is engaged and the process ends. If the input / output speed ratio R1 is less than the predetermined engagement possibility determination value, the process proceeds to step 21, the engagement force of the first clutch 4 is increased, and the process ends.

On the other hand, if it is determined in step 15 that the input / output speed ratio R2 is less than the predetermined engagement possibility determination value, the process proceeds to step 22 and the engagement force of the second clutch 5 is increased.
Go to step 23.

In step 23, the input / output speed ratio R1 is compared with the target value P. If the input / output speed ratio R1 is less than the target value P, the process proceeds to step 24 to maintain the engagement force of the first clutch 4. And finish. When the input / output speed ratio R1 is larger than the target value P, the routine proceeds to step 19, where the engagement force of the first clutch 4 is reduced and the processing is ended.

In the first embodiment, since a small motor having a small maximum output is used, the motor 2 can generate the maximum torque only at a low rotation speed (see FIG. 2). When the start accompanied by the automatic engine restart is at the time of a high load start, since the motor rotation speed is reduced and the second clutch 5 is engaged after the engine ignition, a large motor torque is applied to the drive wheels 11, 11. Can be transmitted,
The acceleration performance of the vehicle can be improved.

When the rotation speed of the motor 2 is reduced after the engine is ignited, the second clutch 5 is engaged at a lower rotation speed than in the conventional case. Therefore, when the second clutch 5 is engaged at a high rotation speed. Compared with the above, it is possible to reduce the transmission torque loss generated in the second clutch 5, and
The durability of the clutch 5 can be improved.

Further, since the target value P is set so that the torque transmission rate of the first clutch 4 becomes large, the torque transmission loss can be minimized. In this embodiment, the motor 2 is Since it has the torque characteristics shown in FIG. 2, when the motor speed is around 320 rpm,
The engagement forces of the first clutch 4 and the second clutch 5 are controlled so that the second clutch 5 is engaged.

In the above-described embodiment, the engine rotary shaft 6, the motor rotary shaft 7, and the input-side rotary shaft 8 of the transmission 3 are rotated to measure the rotational speeds of the respective rotary shafts 6, 7, and 8, respectively. The number sensors 15, 16 and 17 are provided, but instead of the respective rotation speed sensors 15, 16 and 17, the input side torque T _1i of the first clutch 4, the output side torque T _1o of the first clutch 4, A torque detection device capable of measuring the input torque T _2i of the second clutch 5 and the output torque T _2o of the second clutch 5 is provided, and the torque transmission ratio (T _1o / T _1i ) of the first clutch 4 Torque transmission rate of clutch 5 (T
_1o / _T1i ) may be detected. That is,
After the ignition of the engine 1, when the fastening force of the first clutch 4 is reduced, the first clutch 4 may be controlled so that the torque transmission rate of the first clutch 4 becomes close to 100%.

After the engine 1 is ignited, when the engaging force of the first clutch 4 is reduced, a reverse torque is generated in the motor 2 until the input / output rotation ratio R1 of the first clutch 4 reaches the target value P. It is also possible to control so as to shorten the time (see the alternate long and short dash line in FIG. 3). The time until the input / output rotation ratio R1 of the first clutch 4 reaches the target value P depends on the friction of the motor 2 and the torque transfer rate of the second clutch 5, but by causing the motor 2 to generate reverse torque,
The time for sliding the second clutch 5 can be shortened,
It is possible to improve the thermal durability of the second clutch 5 and reduce the transmission torque loss. In this case, at the same time when the rotation speed of the motor 2 reaches the target value, a positive torque is generated in the motor 2.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a system configuration of a drive system of a hybrid vehicle to which the present invention is applied.

FIG. 2 is a correlation diagram showing a relationship between motor torque and rotation speed.

FIG. 3 is an explanatory diagram showing a time transition of a motor rotation speed when the present invention is implemented.

FIG. 4 is an explanatory diagram showing a time transition of assist torque by a motor when the present invention is implemented.

FIG. 5 is an explanatory diagram showing the operation of the first clutch and the second clutch when the control according to the present invention is applied.

FIG. 6 is an explanatory diagram showing clutch characteristics.

FIG. 7 is a flowchart showing the flow of control according to the present invention.

FIG. 8 is a flowchart showing the flow of control according to the present invention.

[Explanation of symbols]

1 ... engine 2 ... Motor generator (motor) 3 ... Transmission 4 ... 1st clutch 5 ... Second clutch 6 ... Engine rotation axis 7 ... Motor rotating shaft 8 ... Input side rotating shaft 12 ... Engine control unit (ECU)

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Claims (6)

[Claims] 1. A drive source comprising an engine and a motor, wherein the engine is automatically stopped when a predetermined condition is satisfied when the vehicle is stopped, and the engine is automatically activated when another predetermined condition is satisfied during the automatic engine stop. A control device applied to a hybrid vehicle that restarts and starts the vehicle, comprising: a first clutch disposed between the engine and the motor; and a first clutch disposed between the motor and a drive wheel of the vehicle. A second clutch, and an engine speed detecting means for detecting the speed of the engine, wherein the engine and the rotation shaft of the motor are connected via the first clutch,
In a control device applied to a hybrid vehicle in which the motor and the drive wheels are connected via the second clutch, the first clutch is in a substantially engaged state when the vehicle starts with automatic restart of the engine. The second clutch is set to a substantially disengaged state, the engine is rotationally driven by the motor, the engine is ignited when the engine reaches a predetermined rotational speed, and the first clutch is predetermined half-engaged after the engine is ignited. A control device for a hybrid vehicle, characterized in that while the engine torque is assisted by the motor as a state, the engagement force of the second clutch is increased to start the vehicle. 2. When the first clutch is brought into a predetermined half-engaged state, the engagement force of the first clutch is controlled so that the rotation speed of the motor becomes a predetermined low rotation speed. The control device for a hybrid vehicle according to claim 1. 3. The control device for a hybrid vehicle according to claim 2, wherein the predetermined low rotation speed is in a rotation speed range close to a high torque range of the motor. 4. When the first clutch is brought into a predetermined half-engaged state, the engagement force of the first clutch is controlled so that the torque transmission rate of the first clutch becomes a predetermined target value. The control device for a hybrid vehicle according to claim 1, wherein the control device is a hybrid vehicle. 5. The vehicle is started in a predetermined half-engaged state of the first clutch only when the engine is in a predetermined high load state.
5. The control device for a hybrid vehicle according to any one of items 4 to 4. 6. The control device for a hybrid vehicle according to claim 1, wherein a reverse torque is generated in the motor when the first clutch is brought into a predetermined half-engaged state.