JP3783647B2 - Control device and control method for idle stop vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device and a control method for an idle stop vehicle that automatically stops and restarts an engine.
[0002]
[Prior art]
For example, in order to avoid exhaust gas emissions when a vehicle is temporarily stopped at an intersection, an idle stop vehicle has been conventionally used that automatically stops the engine when the vehicle stops and then automatically restarts the engine when the vehicle starts. Are known. An example of such an idle stop vehicle is disclosed in Japanese Patent Laid-Open No. 2001-234837. In this publication, an accessory driving motor is connected to the engine by a power transmission belt, and the crankshaft of the engine is driven to rotate by the accessory driving motor when the engine is automatically restarted.
[0003]
[Problems to be solved by the invention]
As described in the above publication, when the engine crankshaft is rotationally driven by a motor connected to the engine via a power transmission belt at the time of automatic engine restart, power transmission is performed each time the engine is automatically restarted. Since high tension is repeatedly applied to the belt, there is a concern that the durability of the power transmission belt is lowered and its life is shortened.
[0004]
In order to suppress the tension acting on the power transmission belt low and improve the life and durability of this power transmission belt, if the upper limit value of the maximum output torque characteristic of the motor is always kept low when the engine is automatically restarted, the engine It takes a long time to complete the automatic restart of the vehicle. For example, even if it is desired to start the vehicle immediately after the automatic restart of the engine, there is a new problem that the vehicle cannot be started immediately. There is a fear.
[0005]
The present invention has been made in view of such problems, and provides a novel idle stop vehicle control device and control method that can effectively improve the life and durability of a power transmission member such as a power transmission belt. The main purpose is to do.
[0006]
[Means for Solving the Problems]
The present invention is a control device for an idle stop vehicle that automatically stops and restarts an engine, and at least when the engine is automatically restarted, a motor that rotationally drives the crankshaft of the engine, and the crankshaft and motor of the engine And a power transmission member for connecting the motor shaft. And it has the maximum output torque change means which changes the maximum output torque characteristic of the motor at the time of the said automatic restart, It is characterized by the above-mentioned.
[0007]
And there is an immediate start request determining means for determining the presence or absence of an immediate start request for promptly starting the vehicle, and the maximum output torque changing means is compared with a case where there is no immediate start request and there is an immediate start request. The upper limit value of the maximum output torque characteristic of the motor is suppressed low. The immediate start request determination unit determines that there is an immediate start request when waiting for a right turn at an intersection, stopping on a slope, or in a traffic jam, for example. The power transmission member is typically a power transmission belt such as a V-ribbed belt wound around a crank pulley provided on the crankshaft of the engine and a motor pulley provided on the motor shaft of the motor.
[0008]
The method for controlling an idle stop vehicle according to the present invention determines whether or not the engine is automatically stopped, determines whether or not there is an automatic restart request for the engine when the automatic stop is being performed, and If there is an immediate start request for promptly starting the vehicle, the engine crank is connected via the power transmission member when there is no immediate start request and when there is no immediate start request. The upper limit value of the maximum output torque characteristic of the motor connected to the shaft is suppressed low, and the motor is driven to automatically restart the engine.
[0009]
【The invention's effect】
According to the present invention, by appropriately changing the maximum output torque characteristic of the motor at the time of automatic restart, the tension acting on the power transmission member can be reduced as necessary. Durability can be effectively improved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on illustrated embodiments. FIG. 1 is a schematic configuration diagram illustrating a control device for an idle stop vehicle according to an embodiment of the present invention. The idle stop vehicle is linked to a crankshaft 10a of the engine 10 using an engine 10 such as a gasoline engine or a diesel engine, a transmission 12 including a known torque converter 11, and a power transmission belt 14 as a power transmission member. Motor 13. The transmission 12 is a continuously variable type that decelerates the rotational driving force of the engine 10 and changes its reduction ratio steplessly and transmits it to the drive wheel side. Instead of such a continuously variable transmission 12, a multistage automatic transmission having a plurality of planetary gear mechanisms or a manual transmission may be used.
[0011]
The motor 13 is an AC motor generator, and can perform both a power running operation (drive) and a regenerative operation (power generation) by a known inverter 15 connected to a battery 16 that stores electric power. That is, when the engine is restarted, which will be described later, the motor 13 is operated in a power manner to rotate the crankshaft 10a of the engine 10, and at the time of deceleration or the like, the motor 13 is regeneratively operated as necessary to regenerate power. When the engine is started for the first time (typically when the engine is started by operating the ignition key), the engine 10 may be cranked by the motor 13 or a well-known starter separate from the motor 13 may be used. The cranking may be performed by using a motor and engaging the starter motor pinion with the ring gear of the engine 10. In any case, at the time of automatic restart from an automatic stop state, which will be described later, the crankshaft 10a of the engine 10 is rotationally driven by the motor 13 connected via the power transmission belt 14.
[0012]
The power transmission belt 14 is a well-known V-ribbed belt formed using, for example, a rubber material or a resin material. The power transmission belt 14 is a crank pulley 10b provided at the tip of the crankshaft 10a of the engine 10 and the tip of the motor shaft 13a of the motor 13. Is wound around a motor pulley 16b provided on the engine 10 and transmits power between at least the engine 10 and the motor 13. Although not shown, the power transmission belt 14 may be wound around an auxiliary machine such as an air compressor or a water pump, or another auxiliary belt wound around the auxiliary machine may be used as an engine. Or you may make it wind around a motor.
[0013]
As various sensors for setting / detecting a vehicle driving state, a brake stroke sensor 21 for detecting the depression amount of a brake pedal, a slope sensor 22 for detecting a vehicle gradient, that is, a slope of the ground, and a left / right turn of the vehicle are set / displayed. Turn signal (direction indicator) 23, a space sensor 24 for detecting the distance between the following vehicle (or the preceding vehicle), a water temperature sensor 25 for detecting the cooling water temperature of the engine 10, the engine 10 and the continuously variable transmission 12 An oil temperature sensor 26 for detecting the oil temperature of the oil is provided. These sensor setting / detection signals are input to a vehicle control unit 30 that controls the operation of the entire vehicle. The vehicle control unit 30 outputs control signals to the engine control unit 31 that controls the fuel injection timing and ignition timing of the engine 10, the battery controller 32 that monitors the storage amount, voltage, current, etc. of the battery 16, and the inverter 15. Signals are input and output by being connected to a motor controller 33 that controls the operation of the motor 13. Each of these control units and controllers is a microcomputer system provided with an I / O interface, CPU, ROM, RAM, etc., and has predetermined functions as will be described later by executing a program stored on the ROM. Realize.
[0014]
FIG. 2 is a flowchart showing the flow of the automatic restart control of the engine 10 according to the present embodiment, and is repeatedly executed by the vehicle control unit 30 and the engine control unit 31, for example, every predetermined time (for example, every 10 ms). In S (step) 1, it is determined whether or not the engine 10 is automatically stopped, specifically, whether or not a flag indicating that automatic stop is set. This automatic stop process is executed by another routine (not shown). For example, when all of the conditions such as the vehicle speed is zero, the charged amount (SOC) of the battery 16 is greater than a predetermined value, and the brake pedal is depressed, the engine is satisfied. Is automatically stopped and its flag is set.
[0015]
If it is determined in S1 that the automatic stop is being performed, the process proceeds to S2, and it is determined whether or not there is an automatic restart request of the engine, specifically, whether or not an automatic restart request flag is set. Typically, an automatic restart request flag is set on the condition that the depression of the brake pedal is released based on the brake stroke sensor 21.
[0016]
If it is determined in S2 that there is an engine automatic restart request, the process proceeds to S3, and it is determined whether or not there is an immediate start request, specifically, whether an immediate start request flag is set (immediate start request determination means). FIG. 3 shows an example of a subroutine for setting an immediate start request flag in S3. In S11, based on the setting state of the turn signal 23 or the like, it is determined whether or not it is waiting for a right turn at a left-hand traffic intersection. In the case of right-hand traffic, it is determined whether it is waiting for a left turn. In S12, based on the detection signal of the slope sensor 22 or the like, it is determined whether or not the vehicle is in a situation where the vehicle should be advanced quickly without moving backward, such as when stopping on a steep climb. In S13, based on the detection signal of the space sensor 24, etc., it is determined whether there is a situation in which the distance between the vehicle and the rear vehicle (or the front vehicle) is short due to traffic jams and the vehicle should start following the front vehicle quickly. If any of S11, S12, and S13 is affirmed, it is determined that there is a request to start the vehicle quickly in a short time, and the process proceeds to S14, and an immediate start request flag is set. If all the determinations in S11, S12, and S13 are negative, the process proceeds to S15, where there is no immediate vehicle start request, and the vehicle is allowed to start relatively slowly, and the immediate start request flag is reset (released). . In this embodiment, the presence / absence of the vehicle immediate start request is determined based on the three requirements S11 to 13. However, the present invention is not limited to this, and the immediate start request is determined based on one or more requirements including other requirements. The presence or absence may be determined.
[0017]
Referring to FIG. 2 again, when there is no immediate start request, the determination in S3 is denied and the process proceeds to S4, where the upper limit value of the maximum output torque characteristic of the motor 13 is limited to a low value (maximum output torque changing means). In other words, when there is an immediate start request, the maximum output torque of the motor 13 is not limited at all. FIG. 4 simply shows the maximum output torque characteristic of the motor 13. The solid line (a) in the figure corresponds to the characteristic when the upper limit value of the maximum output torque characteristic is not limited, that is, when there is an immediate start request, and the broken line (b) indicates the upper limit value of the maximum output torque characteristic. This corresponds to a characteristic in which the predetermined upper limit value T0, which is lower by a predetermined amount ΔT than in the case of not limiting, is suppressed, that is, there is no immediate start request. This upper limit value T0 (or reduction amount ΔT) is set in advance in consideration of the tension acting on the power transmission belt 14 and the time required for the complete explosion of the engine 10 (start of the vehicle).
[0018]
In S5, the crankshaft 10a of the engine 10 is rotationally driven by driving the motor 13 within the range of the maximum output torque as shown in FIG. Start. That is, the crankshaft 10a of the engine 10 is cranked by the motor 13, and fuel injection and ignition are started when the cylinder discrimination is completed.
[0019]
FIG. 5 is a timing chart showing the torque characteristics of the motor 13, the engine speed, and the tension of the power transmission belt 14 when the engine is automatically restarted. In FIG. 5, the solid line characteristic indicates the characteristic when the maximum output torque of the motor 13 is not limited, that is, when there is a vehicle immediate start request, and the broken line characteristic indicates the upper limit value of the maximum output torque of the motor 13. The characteristic is shown when T0 is limited, that is, when there is no vehicle immediate start request.
[0020]
As shown in the figure, when the maximum output torque characteristic of the motor 13 is not limited, the output current of the inverter 15 is set to the maximum value until the time point P1 when the engine speed reaches the target speed (typically idle speed). The motor 13 is continuously driven at the maximum output torque. On the other hand, when the upper limit value T0 of the maximum output torque characteristic of the motor 13 is set, the output current of the inverter 15 is set to a value lower than the maximum value until the engine speed reaches a predetermined value N0 (FIG. 4). In this case, the output torque of the motor 13 is suppressed to the upper limit value T0, and when the engine speed exceeds the predetermined value N0, the motor 13 is driven with the maximum output torque until the time point P1 ′ at which the target speed is reached. Therefore, when the upper limit value T0 of the maximum output torque of the motor 13 is limited, the time required for the engine speed to reach the target speed becomes longer by Δα than when the upper limit value T0 is not limited. Although this time becomes long, the maximum value of the tension acting on the power transmission belt 14 is suppressed by Δβ. For this reason, the lifetime and durability of the power transmission belt 14 are improved, and the expected performance can be maintained over a long period of time.
[0021]
As shown in the example of FIG. 5, when the engine speed is maintained at the target speed after the engine is automatically restarted, the engine speed immediately after the engine speed exceeds the target speed (immediately after the complete explosion). Since the motor 13 is temporarily switched to the regenerative operation in order to reduce the number to the target rotational speed, the belt tension is temporarily lower than the initial tension F0 that is always applied by a known auto tensioner or the like.
[0022]
As described above, in this embodiment, at the time of automatic restart from the engine automatic stop state, it is determined whether or not there is an immediate start request, and if there is an immediate start request, the maximum output torque of the motor 13 is not limited immediately. When automatic restart is performed and there is no immediate start request, the upper limit value of the maximum output torque of the motor 10 is limited and suppressed low. For this reason, it is possible to effectively improve the life and durability of the power transmission belt 14 by reducing the tension acting on the power transmission belt 14 while automatically restarting the engine 10 as necessary.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an idle stop vehicle control device according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a flow of engine automatic restart control of the embodiment.
FIG. 3 is a subroutine for determining whether or not there is a vehicle immediate start request according to the embodiment.
FIG. 4 is a characteristic diagram showing a maximum output torque characteristic of the motor of the embodiment.
FIG. 5 is a timing chart showing changes in motor torque, engine speed, and belt tension when the engine is automatically restarted in the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Engine 13 ... Motor 14 ... Power transmission belt (power transmission member)

Claims (4)

A motor that rotationally drives the crankshaft of the engine at least when the engine is automatically restarted, and a power transmission member that connects the crankshaft of the engine and the motor shaft of the motor. In a control device for an idle stop vehicle that performs automatic restart,
Maximum output torque changing means for changing the maximum output torque characteristic of the motor at the time of the automatic restart ;
An immediate start request determination means for determining whether or not there is an immediate start request for quickly starting the vehicle,
The maximum output torque changing means suppresses the upper limit value of the maximum output torque characteristic of the motor to be lower when there is no immediate start request and when there is an immediate start request . Control device. The prompt start request determination means includes at least one of a means for determining a right turn waiting at an intersection, a means for determining a stop on a hill, and a means for determining that there is a traffic jam. The control apparatus of the idle stop vehicle of 1 . The power transmission member includes a crank pulley provided on a crank shaft of the engine, according to claim 1 or 2 characterized in that it is a motor pulley and power transmission belt which is wound around the provided motor axis of the motor Control device for idle stop vehicles. Determining whether the engine is automatically stopped;
Determining whether there is an automatic engine restart request when the automatic stop is in progress;
Determining whether there is an immediate start request for quickly starting the vehicle when there is an automatic restart request; and
Suppressing the upper limit value of the maximum output torque characteristic of the motor connected to the crankshaft of the engine via the power transmission member when compared to when there is no immediate start request and when there is the immediate start request;
Driving the motor to automatically restart the engine;
A control method for an idle stop vehicle having

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