JP2001163087A - Start controller for idle-stop vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smooth a restart of an idle-stop vehicle in an ascent and a descent. SOLUTION: When release of a brake pedal is detected during an idle-stop state of an engine, the engine is started by a motor while continuing braking of the vehicle by a mechanical braking means, and when complete explosion of the engine is detected, the braking by the mechanical braking means is released.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling the start of an idle stop vehicle that stops an engine when the vehicle stops.

[0002]

2. Description of the Related Art In order to reduce fuel consumption and exhaust gas, a so-called idle stop vehicle is known in which the idling of an engine is stopped when the vehicle is stopped at a traffic light or the like and the engine is restarted by a motor when the vehicle starts moving.

[0003] Also, there is known a hybrid vehicle provided with an engine and a motor as a driving source for the vehicle, and running on one or both of the engine and the motor in accordance with the driving conditions (for example, Japanese Patent Application Laid-Open No. HEI 9-110572). 11-9
No. 8612).

[0004]

In order to realize an idle stop function in a hybrid vehicle, when a driver releases his / her foot from a brake pedal and depresses an accelerator pedal, the motor starts and the engine is restarted. Will do.

However, until the engine is started at the time of starting and the driving force is generated, the vehicle is started only by the driving force of the motor. In a hybrid vehicle equipped with a small-capacity motor and a battery, when starting on a slope, There is a possibility that the driving force is insufficient and the vehicle goes backward. Further, when starting on a downhill, the vehicle may be greatly accelerated due to insufficient regenerative braking force by the motor.

On the other hand, even in a hybrid vehicle equipped with a relatively large capacity motor and a battery, when the remaining capacity of the battery is small, the driving force of the motor is limited.
A similar problem may occur.

An object of the present invention is to make it possible for an idle stop vehicle to start on an uphill or downhill road smoothly.

[0008]

Means for Solving the Problems The present invention will be described with reference to FIG. 1 showing the configuration of one embodiment. (1) The invention according to claim 1 includes an engine 1 as a driving source for driving a vehicle, A motor 2 for starting the engine 1, complete explosion detecting means 10 and 16 for detecting a complete explosion of the engine 1,
Mechanical braking means 9 for mechanically braking the vehicle; brake release detecting means 17 for detecting the release state of the brake pedal 18; and when the release of the brake pedal 18 is detected when the engine 1 is in the idling stop state. And a control means 10 for starting the engine 1 by the motor 2 while continuing to brake the vehicle by the mechanical braking means 9 and releasing the braking by the mechanical braking means 9 when the complete explosion of the engine 1 is detected. (2) The start control device for an idle stop vehicle according to claim 2 detects the current flowing through the motor 2 by the complete explosion detection means 10 and 16, and completes the engine 1 when the detected current becomes smaller than a predetermined value when the engine is started. It was decided to have exploded. (3) In the start control device for an idle stop vehicle according to a third aspect, the motor 2 is directly connected to the output shaft of the engine 1, and is driven and controlled by the inverter 7 so as to function also as a vehicle driving source. .

In the section of the means for solving the above-described problem, a diagram of one embodiment is used for easy understanding of the description, but the present invention is not limited to the embodiment. .

[0010]

According to the first aspect of the present invention, when the release of the brake pedal is detected while the engine is in the idling stop state, the motor is operated by the motor while the braking by the mechanical braking means is continued. Since the engine is started and the braking by the mechanical braking means is released when the complete explosion of the engine is detected, it is possible to smoothly start from the idling stop state. For example, even if the driver releases the brake pedal on a hill start, the mechanical brake operation is maintained until the engine completely explodes to generate the driving force, so that the vehicle is prevented from reversing. Also,
Even if the driver releases the brakes when the vehicle starts moving backwards, the mechanical brakes are maintained until the engine completely explodes, preventing the vehicle from accelerating as soon as the brake pedal is released. can do. (2) According to the invention of claim 2, the current flowing to the motor is detected, and when the detected current becomes smaller than a predetermined value at the time of starting the engine, it is determined that the engine has completely exploded. The detection can be reliably performed, whereby the vehicle can be smoothly started from the idling stop state. (3) According to the third aspect of the invention, the motor is directly connected to the output shaft of the engine, and the drive is controlled by the inverter to function also as the driving source of the vehicle. The complete explosion of the engine can be detected based on the measured current, and there is no need to install a new current sensor for detecting the complete explosion of the engine. In addition, since the motor is directly connected to the engine, the engine status changes quickly and the motor current And a complete explosion of the engine can be detected quickly and reliably.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a hybrid vehicle having an engine and a motor as driving sources for driving and running with one or both of the engine and the motor according to driving conditions will be described. . Note that the present invention is not limited to a hybrid vehicle, and can be applied to all idle stop vehicles other than the hybrid vehicle.

FIG. 1 is a diagram showing a configuration of an embodiment. A power train of a vehicle according to one embodiment includes an engine 1, a motor 2, a transmission 3, a drive shaft 4, and a differential device 5, and is driven by the engine 1 and / or the motor 2 according to running conditions. A drive force is generated to drive the drive wheels 6 via the transmission 3, the drive shaft 4 and the differential device 5. Motor 2
Drives the engine 1 to start and generates a regenerative braking force during braking.

The illustration of a clutch or a torque converter for interrupting the driving force is omitted. Further, in this embodiment, an example in which the motor 2 is directly connected to the output shaft of the engine 1 is shown. However, the two need not necessarily be directly connected, and any configuration in which the engine 1 and the motor 2 are mechanically connected. Good. Transmission 3 is a CVT
, Or an automatic or manual stepped transmission.

The inverter 7 is a vector control inverter, which converts the DC power of the battery 8 into three-phase AC power and supplies it to the motor 2 to generate a driving force from the motor 2 and to convert the regenerative AC power of the motor 2 into DC power. The power is converted into electric power and supplied to the battery 8, and the battery 8 is charged. The brake unit 9 mechanically generates a braking force by driving a hydraulic braking mechanism of the drive wheel 6 and a driven wheel (not shown). In addition, the hydraulic braking mechanism of the drive wheel 6 and the driven wheel is connected to the brake unit 9 and is also directly connected to the brake pedal 18.
The driver operates the brake pedal 18 regardless of whether the
, The vehicle is mechanically braked by the hydraulic brake mechanism. On the other hand, even if the driver releases the brake pedal 18, the mechanical braking force acts on the vehicle when the brake unit 9 is operating.

The control unit 10 comprises a microcomputer and peripheral parts such as a memory, and controls an intake air amount control device, a fuel injection control device and an ignition timing control device (not shown) to control the rotation speed and torque of the engine 1. While controlling, the inverter 7 is controlled to control the rotation speed and the torque of the motor 2. The control unit 10 also controls the brake unit 9 to adjust the mechanical braking force.

The control unit 10 includes a vehicle speed sensor 11, an accelerator sensor 12, a water temperature sensor 13,
Engine rotation sensor 14, motor rotation sensor 1
5, motor current sensor 16, brake switch 17
Are connected. The vehicle speed sensor 11 detects the running speed of the vehicle, and the accelerator sensor 12 detects the amount of depression of the accelerator pedal. Further, a water temperature sensor 13 detects a cooling water temperature of the engine 1 and outputs
Detects the rotation speed of the engine 1. Further, the motor rotation sensor 15 detects the rotation speed of the motor 2.
The motor current sensor 16 measures a three-phase AC current of the motor 2 and detects a DC torque component current from the three-phase AC current by three-phase / two-phase conversion. This torque current is proportional to the output torque of the motor 2. The brake switch 17 is turned on when the amount of depression of the brake pedal 18 exceeds a predetermined value, and detects the depressed state and released state of the brake pedal 18.

FIG. 2 is a diagram showing a control system of the motor 2. The control unit 10 constitutes a feedback control system of the motor 2 by software of a microcomputer, and controls the rotation speed of the motor 2 and the current corresponding to the torque. This feedback control system includes a main loop that performs feedback control of the rotation speed, and a minor loop that performs feedback control of the torque current. In the main loop, the rotation speed of the motor 2 detected by the rotation sensor 15 is compared with a rotation speed command value,
The rotation speed control unit generates a torque current command value for setting the difference between the two, that is, the rotation speed deviation to zero. In the minor loop, the torque component current of the motor 2 detected by the current sensor 16 matches the torque component current command value.
The inverter 7 is controlled by the current control unit.

FIG. 3 is a diagram showing changes in the engine speed Ne and the motor current Ia when the motor 2 starts the engine. At the time of starting the engine, a rotation speed command value for starting the engine is given to the above-described motor control system, and a current command value for torque for matching the actual rotation speed detection value Ne to the rotation speed command value is generated. The divided current detection value Ia is controlled so as to match the torque divided current command value, and AC power is supplied to the motor 2 so that the motor 2
Starts.

The engine 1 mechanically connected to the motor 2 is driven by the motor 2 to rotate, and controls the amount of intake air.
The fuel injection control and the ignition control are performed, and the engine 1 starts. The motor 2 operates until the engine 1 generates torque and rotates by itself, that is, until the engine 1 completely explodes.
You have to drive to overcome the friction.
After the complete explosion of the engine, the engine 1 rotates by its own driving force, so that the motor 2 does not need to drive the engine 1 and the load is reduced. Therefore, the rotation speed of the motor 2 increases by an amount corresponding to the lightening of the engine load, and the deviation between the rotation speed command value and the rotation speed detection value decreases. Therefore, the current command value decreases, and as a result, the current detection value Ia also decreases. Decrease.

That is, as shown in FIG. 3, the detected current value Ia of the torque of the motor 2 at the time of starting the engine rapidly decreases when the engine speed Ne increases and the engine 1 completely explodes. Therefore, if the detected current Ia for the torque at the time of starting the engine is monitored, the complete explosion of the engine 1 can be known. In this embodiment, a threshold value Io of a torque component current for determining a complete explosion of the engine 1 is set, and when the detected torque component value Ia at the time of starting the engine becomes smaller than the threshold value Io, the engine 1 Has completely exploded,
That is, it is determined that the start has been completed.

FIG. 4 is a flowchart showing a start control program according to one embodiment. The operation of the embodiment will be described with reference to this flowchart. The CPU of the control unit 10 determines that the ignition key of the vehicle is O
When set to the N position, the control program is executed every predetermined time, for example, every 100 msec.

In step 1, a flag for giving a stop command to engine 1 and motor 2 is set (1).
It is confirmed whether or not it has been set. If it has been set, the process proceeds to step 7, and if it has been reset (0), the process proceeds to step 2. If the stop command flag has been reset, it is checked in step 2 whether the brake pedal is depressed by the brake switch 17. If the brake pedal is depressed, the process proceeds to step 3; otherwise, the process ends.

When the stop command flag for stopping the engine 1 and the motor 2 is reset and the brake pedal is depressed, the vehicle speed sensor 11 determines in step 3 that the vehicle speed is almost 0, that is, whether the vehicle is in a stopped state. Check whether or not. If the vehicle is stopped, the process proceeds to step 4, and if the vehicle is running, the process ends. When the vehicle is stopped,
In step 4, a timer for measuring the time after the vehicle is stopped is started.

In step 5, it is confirmed whether or not 3 seconds or more have elapsed since the vehicle was stopped based on the time value of the timer.
Otherwise, return to step 3 and repeat the above processing. If the brake pedal is depressed, the vehicle speed is almost 0, and more than 3 seconds have elapsed since the vehicle stopped, step 6
Then, the stop command flag is set (1), the brake flag is set (1), and the process ends. The stop command flag is referred to by a control program (not shown) for the engine 1 and the motor 2, and the engine 1 and the motor 2 are stopped in response to the setting (1) of the stop command flag, and the idle stop state is set. The brake flag is referred to by a brake control program (not shown), and the mechanical brake is operated by the brake unit 9 in response to the setting (1) of the brake flag.

If it is determined in step 1 that the stop command flag has already been set, the flow advances to step 7 to check whether the brake switch 17 has released the brake pedal. When the engine 1 and the motor 2 are stopped and in the idling stop state, and the brake pedal is not released, the processing ends.

On the other hand, when the engine 1 and the motor 2 are stopped, that is, when the brake pedal is released in the idle stop state, the routine proceeds to step 8, where the stop command flag is reset (0). The stop command flag is referred to by a control program for the engine 1 and the motor 2, and the motor 2 starts the engine 1 in response to the reset (0) of the stop command flag.

Even if the brake pedal 18 is released in step 7, the brake flag is kept set (1), and the mechanical braking of the vehicle is continued by the brake unit 9.

In step 9, the motor current sensor 16 detects the torque component current Ia of the motor 2, and in the following step 10, it is checked whether the torque component current Ia is equal to or greater than the threshold value Io. If the torque component current Ia is equal to or greater than the threshold value Io, it is determined that the engine 1 has not yet completely exploded, and the process returns to step S10.

Thereafter, when the torque component current Ia becomes smaller than the threshold value Io, it is determined that the engine 1 has completely exploded,
Proceed to step 11 to reset the brake flag (0)
I do. This brake flag is referred to by the brake control program, and the mechanical braking by the brake unit 9 is released in response to the reset (0) of the brake flag.

As described above, in a state where the vehicle is stopped and the engine 1 is idling stopped, the engine 2 is started by the motor 2 while the mechanical brake is operated even if the brake pedal is released. Then, the mechanical brake operation is maintained until the complete explosion of the engine 1 is detected due to the decrease of the torque component current Ia of the motor 2, and the torque component current Ia becomes smaller than the threshold value Io, and the complete explosion of the engine 1 occurs. Release the mechanical brake when it is detected. Thus, even if the driver releases the brake pedal, for example, on a slope start, the mechanical brake is maintained until the engine completely explodes to generate the driving force, thereby preventing the vehicle from moving backward. In addition, even if the driver releases the brakes when the vehicle starts moving backwards, the mechanical brakes are maintained until the engine completely explodes, so the vehicle accelerates greatly as soon as the brake pedal is released. Can be prevented.

The motor current sensor 16 is a sensor originally used for controlling the torque of the motor 2. In the start control of the vehicle according to the embodiment, the motor current sensor 16 detects the complete explosion of the engine 1 by using the motor current sensor 16. Therefore, it is not necessary to newly provide a sensor for detecting a complete explosion of the engine 1, and the apparatus can be configured at low cost.

In the above-described embodiment, an example in which the complete explosion of the engine 1 is detected by the torque component current Ia of the motor 2 has been described. However, in an idle stop vehicle other than the hybrid vehicle, a starter for starting the engine is used. Since the current of the motor is measured and the current of the starter motor decreases when the engine completely explodes, it may be determined that the engine has completely exploded when the current of the starter motor falls below a predetermined value. When the engine completely explodes, the engine speed rapidly increases. Therefore, the engine speed at the time of starting may be monitored, and if the speed exceeds a predetermined value, it may be determined that the engine has completely exploded.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment.

FIG. 2 is a diagram illustrating a control system of a motor.

FIG. 3 is a diagram illustrating an engine rotation speed Ne and a motor torque current Ia at the time of engine start.

FIG. 4 is a flowchart showing a start control program according to one embodiment.

[Explanation of symbols]

 Reference Signs List 1 engine 2 motor 3 transmission 4 drive shaft 5 differential device 6 drive wheel 7 inverter 8 battery 9 brake unit 10 control unit 11 vehicle speed sensor 12 accelerator sensor 13 water temperature sensor 14 engine rotation sensor 15 motor rotation sensor 16 motor current sensor 17 Brake switch 18 Brake pedal

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Claims (3)

[Claims] 1. An engine as a driving source of a vehicle, a motor for starting the engine, complete explosion detecting means for detecting a complete explosion of the engine, mechanical braking means for mechanically braking the vehicle, Brake release detection means for detecting the release state of the brake pedal; and when the release of the brake pedal is detected when the engine is in the idling stop state, the motor is used to continue braking the vehicle by the mechanical braking means. Control means for starting the engine and releasing braking by the mechanical braking means when a complete explosion of the engine is detected. 2. The start control device for an idle stop vehicle according to claim 1, wherein the complete explosion detection means detects a current flowing through the motor, and the engine detects a detected current that is smaller than a predetermined value when the engine is started. A start control device for an idle stop vehicle, which determines that the vehicle has completely exploded. 3. The start control device for an idle stop vehicle according to claim 2, wherein the motor is directly connected to an output shaft of the engine, and is driven and controlled by an inverter to function also as a vehicle driving source. Start control device for an idle stop vehicle.