JP2002213279A - Start control device for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Problem] To prevent sudden start when starting an engine. SOLUTION: The driving of a motor generator is started at a timing when a brake is released, and a fuel cut is stopped when an accelerator is depressed. The throttle opening during driving by the motor generator is gradually changed by the upper limit guard value so that it does not suddenly increase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an electric motor connected to a drive shaft of an internal combustion engine, and drives the electric motor to drive the internal combustion engine in a state where the rotational force of the internal combustion engine can be transmitted to driving wheels. The present invention relates to a start control device for an internal combustion engine that controls the start of the internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, there has been known an eco-run system (economy run system) for automatically stopping an engine when a vehicle stops (idle). By using this eco-run system, unnecessary fuel consumption while the vehicle is stopped can be reduced, and exhaust gas can also be reduced.

[0003] In such an eco-run system,
When a predetermined condition is satisfied while the vehicle is stopped, the engine is stopped, and the engine is restarted when starting. For this purpose, it has a motor generator which can be connected to the output shaft of the engine, generates electric power by the motor generator when the engine is running, and starts the engine by the driving force of the motor generator when starting the engine, and at the same time, Start running. Normally, when the engine is stopped while the vehicle is stopped, turning off the brake is used as a trigger to rotate the engine with the motor generator and start running with the torque of the motor generator.

[0004] When the accelerator is depressed, the fuel cut is released, and the vehicle shifts to running on the engine.

[0005]

Here, in an automatic transmission (AT) vehicle, there is a driver who depresses a brake with a left foot and depresses an accelerator with a right foot. In the case of such a driver, when the brake is turned off,
The accelerator may already be depressed. In this case, since the fuel cut is released at the same time when the engine is rotated by the motor generator, there is a problem that the engine speed rises rapidly and the start becomes unnecessarily sudden.

[0006] In addition, even when the stepping from the brake to the accelerator is performed instantaneously, there is a possibility that the start may be suddenly similarly increased.

[0007] The present invention has been made in view of the above problems, and has as its object to provide a start control device capable of effectively preventing sudden start.

[0008]

SUMMARY OF THE INVENTION The present invention has an electric motor connected to a drive shaft of an internal combustion engine, and drives the electric motor to drive the internal combustion engine in a state where the torque of the internal combustion engine can be transmitted to driving wheels. A start detecting device for detecting depression of an accelerator pedal; and a throttle opening corresponding to the depression of an accelerator pedal during motoring by driving the electric motor. And a throttle opening control means for gradually increasing the throttle opening to the maximum.

As described above, during motoring of the internal combustion engine by the electric motor, the throttle opening is gradually changed until it reaches the throttle opening corresponding to the depression of the accelerator. Thus, when the accelerator is depressed beforehand at the start of motoring by the electric motor or when the accelerator is depressed immediately, it is possible to prevent a sudden start due to a sudden opening of the throttle.

It is preferable that the throttle opening control means changes the degree of gradually increasing the throttle opening based on the timing of depressing an accelerator pedal. Thus, in a state where the accelerator pedal is depressed early and the rotation of the internal combustion engine due to motoring has not yet increased, the throttle is rapidly opened by setting the degree of gradually increasing the throttle opening to a small value. A sudden start due to the accident can be prevented more effectively.

It is preferable that the throttle opening control means changes the degree to which the throttle opening is gradually increased based on the depression amount of an accelerator pedal.
As a result, when the driver steps on the accelerator greatly, the throttle opening changes sooner, and the driver feels less uncomfortable.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a vehicle engine system including an automatic engine stop device of the present invention.

The engine 2 is a gasoline engine,
Inject fuel directly into each cylinder. In particular, stratified combustion and homogeneous combustion can be switched according to the timing of the fuel injection. That is, by injecting fuel at a timing close to the ignition timing, a layer with a high fuel concentration can be formed in the upper part of the cylinder, stratified combustion is performed, and the fuel injection timing is advanced, so that the fuel is injected into the cylinder. The fuel can be mixed with the whole and homogeneous combustion is performed. In order to achieve homogeneous combustion, fuel may be supplied in front of the cylinder such as an intake port in the cylinder head.

The output of the engine 2 is transmitted from the crankshaft 2a to the wheels via a torque converter 4, an automatic transmission (automatic transmission) 6, and an output shaft 6b. A pulley 12 is connected to the other end of the crankshaft 2 a via an electromagnetic clutch 10.
2, pulleys 16, 18,
20 is rotated. The pulley 16 drives the power steering pump 22, the pulley 18 drives the air conditioner compressor 24, and the pulley 20
Thereby, motor generator 26 is driven. In addition,
By turning on / off the electromagnetic clutch 10, the connection between the pulley 12 and the crankshaft 2a is controlled.

A battery 30 for a high-voltage power supply (for example, 36 V) is connected to the motor generator 26 via an inverter 28. The motor generator 26 functions as either a motor or a generator by switching control of the inverter 28.

When functioning as a motor (drive mode)
The power from the high voltage battery 30 is converted into a predetermined AC current by the inverter 28 and
6 to drive the motor generator 26. The driving force of the motor generator 26 is transmitted to the crankshaft 2a of the engine 2 via the pulleys 20 and 12, and the engine 2
6 is rotated.

On the other hand, when functioning as a generator (power generation mode), the rotation of the engine 2 is transmitted to the motor generator 26 via the pulleys 12 and 20. Then, the rotation of the motor generator 26 passes through the inverter 28,
The power is converted into DC power and supplied to the battery 30, and the battery 30 is charged.

When the motor generator 26 is in the drive mode, the output torque is controlled by the switching of the inverter 28, and when the motor generator 26 is in the power generation mode, the power generation amount is controlled by the switching of the inverter 28. You.

A battery 30 for a low-voltage power supply (for example, 12 V) is connected to a battery 30 via a DC / DC converter 32.
4 is connected, and the power of the battery 30 is DC / DC
The voltage is converted to a predetermined low voltage by the converter 32 and the battery 34 is charged. The output of the battery 34 is used as a power source for various devices mounted on the vehicle. The electric hydraulic pump for controlling the automatic transmission 6 is driven by a high voltage from the battery 30. A starter 36 is provided for cold start of the engine.

An intake pipe 2b which is an intake path to the engine 2
Is provided with a throttle valve 2c for adjusting the intake air amount. The opening of this throttle valve is adjusted by a throttle valve motor 2d. This opening control is performed, for example, in accordance with the depression amount of the accelerator pedal 39 detected by the accelerator opening sensor 39a.
Further, the accelerator pedal 39 has an idle switch 3 for detecting a state in which the accelerator pedal 39 is not depressed.
9b is also provided. The opening of the throttle valve 2c is detected by a throttle opening sensor 40.

In addition to the above-described accelerator opening sensor 39a, idle switch 39b, throttle opening sensor 40, and brake switch, a vehicle speed sensor, an output shaft rotation speed sensor for detecting the rotation speed of the output shaft of the automatic transmission 6, and the automatic transmission 6 Shift position sensor for detecting the shift position of the vehicle, engine speed sensor for detecting the engine speed, eco-run switch for instructing the driver to execute the eco-run system, air conditioner switch for air conditioner, water temperature sensor for detecting engine coolant temperature, battery The voltages at 30, 34 and other detected values are input to an electronic control unit (ECU) 46. EC
The U46 is mainly configured by a microcomputer, and performs various data processing according to a program written in an internal ROM. Then, based on the processing result, driving of the throttle valve motor 2d, turning on / off of the electromagnetic clutch 10, switching of the inverter 28, starter 36, power steering pump 22, air conditioner compressor 24, fuel injection by the fuel injection valve 50, and other Controls actuators, etc.

The operation at the time of restarting the engine in such a system will be described with reference to FIG.

First, it is determined whether a restart request has been issued (S1). This judgment is made with the variable ecmdo ≠ 4 and the variable ecomode
= 4. Where the variable ecode
Is a variable indicating the state of the eco-run in the current situation, and is determined from the current sensor output and the like. ecomod
e = 4 indicates a state in which the engine is started. on the other hand,
In the processing of this flowchart, there is a processing of ecmdo = ecomode (S18 described later), and ecmdo indicates the state of the previous eco-run. So, ecmdo ≠ 4 and eco
The fact that mode = 4 indicates that the ecode has changed to 4 for the first time, and it can be detected that there has been a request to restart the engine.

If the determination in S1 is YES, a variable ctaupg which is a counter indicating the restart elapsed time used in the control described later is cleared to 0 (S2). That is, this time is the time of the start of counting.

If NO in S1 and if the process in S2 is completed, it is determined whether or not a flag xtaupg indicating whether or not the throttle upper limit guard process is being executed is OFF (S3). If this flag xtaupg is off, the initial value t_taupg of the throttle upper limit guard is set to the target throttle opening t_t.
Atgt is set (S4). S4 is a process when the upper limit guard process is not being performed. At this time, the throttle target opening degree t_tatgt is a value learned as the throttle fully closed position.

If NO in S3 or if the process in S14 is completed, the target throttle opening (t_tatg
t) and the current throttle upper limit guard value (taupg) (ta
sub) is calculated (S5). Here, the target opening t_tatgt
Is the throttle opening determined by the amount of depression of the accelerator.

Next, the reflection amount taupgre for calculating the gradual change amount of the opening is calculated based on the target opening t_tatgt and the elapsed time after restart ct.
It is determined from a map (table) with aupg (S6). As shown in Table 1, this map is set such that the larger the target opening (the larger the accelerator depression amount) and the longer the time elapsed from the restart, the larger the reflection amount. That is, the setting is such that the reflection amount increases as time elapses, and the reflection amount increases faster as the depression amount increases. This characteristic can be arbitrarily set according to the contents of the map.

[0029]

[Table 1]

The difference obtained in S5 is multiplied by the difference obtained in S5 (tasub.times.taupgre) to calculate the opening degree gradual change addition amount (taupgadd) (S7). Then, it is checked whether or not the throttle upper limit guard is being executed (xtaupg = ON) (S8).

If the determination in S8 is YES, that is, if the throttle is being executed, the previous throttle upper limit guard value (taupg) is set to S7.
The upper limit guard value (t_taupg) is updated by adding the gradual change addition amount (taupgadd) obtained in step (S9). Then, the obtained upper limit guard value (t_taupg) is equal to the target throttle opening (t_t
atgt) is determined (S10).

If the determination in S10 is YES, the upper limit guard can be ended, so the target throttle opening (t_tatgt) is substituted for the upper limit guard value t_taupg, and
It is determined that the upper limit guard process has been completed, and the flag xtaupg is turned off (S11).

If the determination in S8 or S10 is NO and the process in S11 is terminated, it is checked whether the fuel cut state at the time of engine stop due to idle stop has been released to shift to engine start. That is, it is determined whether the variable (xfcstpm) indicating the fuel cut state in the previous process is ON and the variable (xfcstp) in the current process is OFF (S12). By this determination, it can be determined whether the fuel cut has been turned off for the first time.

If the determination in S12 is YES, since the fuel cut has been canceled this time, the flag xtaupg is set to ON to start the throttle upper limit guard process (S13). In the case of NO in S12 and when the process of S13 is completed, the temporary upper limit guard value t_taupg calculated previously is stored as the upper limit guard value etaupg (S14).

When the process of S14 is completed, it is determined whether or not the upper limit guard of the throttle opening is actually performed (S15). That is, (i) the accelerator is fully closed and the fuel is cut off, and the elapsed time after restart is less than A seconds (for example, 2.5 seconds); (ii) the accelerator is depressed (open), and the upper limit guard is set. It is determined whether the process is being executed (the upper limit guard value has not yet caught up with the target opening degree, and the gradual change is being executed).

If the determination in S15 is YES, the target opening t_tatgt is compared with the upper limit guard value taupg to perform the upper limit guard process (S16). If the determination in S16 is YES, the upper limit guard value taupg is substituted for the target opening value t_tatgt to execute the upper limit guard process (S1).
7).

In S15 or S16, NO
When the processing of S17 is completed, the fuel cut state and the eco-run operation state are stored (S18). That is, the fuel cut state and the eco-run operation state in this process are stored as xfcstpm ← xfcstp and ecmdo ← ecomode. In this 18, the stored state is used as the previous state in the next processing.

When the upper limit guard process is performed in this manner, the target opening of the throttle is determined in S17.
t_tatgt is determined, and the actual throttle opening is controlled by the target opening t_tatgt. Therefore, when the upper limit guard process is being performed, the throttle opening is determined by the upper limit guard value t_taupg. The upper limit guard value t_taupg is equal to the reflection amount taupg determined in S6.
re gradually changes over time,
The throttle opening can be gradually changed.

The throttle target opening t_tatgt is a non-linear opening that defines the relationship between the amount of depression of the accelerator pedal and the throttle opening, a cruise control opening, and an opening from ECT that controls the throttle opening during automatic shifting. Requirements, ISC to maintain engine idling
It is updated by another process based on the opening and the like. Then, the updated value is written to the temporary RAM as t_tatgt, and the upper limit guard process of FIG. 2 is performed in that state to determine the final throttle opening.

By such processing, upper limit guard processing is performed as shown in FIG. That is, it is assumed that the engine is stopped while the vehicle is stopped with the brake depressed. When the brake is released in this state, the eco-run mode changes from the stopped ecode = 3 to the start mode ecode = 4. As a result, the electromagnetic clutch 10 is turned on and the motor generator 26
Is driven and controlled using the engine idle speed (for example, 600 rpm) as the target speed. Then, as shown in the figure, the engine speed ne increases sequentially. Then, in this example, at the engine speed of 500 rpm, the normal mode is set to the eco-run mode ecode = 1. If the fuel cut is actually stopped within the range described in the specification of the present application, there is no problem even if the mode is switched to the normal operation mode.

On the other hand, the variable ctaupg for counting the elapsed time from the start mode is once cleared to 0,
Counts the passage of time and rises.

Here, if the accelerator is not depressed after releasing the brake, the fuel cut is
When the engine speed reaches almost idle speed,
Aborted. In this example, when 2500 ms has elapsed, the fuel cut is stopped and the engine is started. Up to this point, the driving force of the motor generator
The vehicle will creep. Then, since the fuel is supplied after the idling speed has already reached the idling speed and the engine is started, the starting is smooth, the running is started, and there is almost no engine starting shock.

In the case of creep running in which the accelerator is not depressed, the target throttle opening is guarded by the upper limit guard value taupg in S4 or S17 of FIG. Therefore, in this example, the target throttle opening is slightly reduced by this processing.

On the other hand, if the accelerator is depressed after releasing the brake, the determination in S12 is YES at that time.
And the flag xtaupg is turned ON. At this point, the fuel cut is stopped and the engine is started.

On the other hand, the target throttle opening is gradually changed by the processing of FIG. In other words, the target throttle opening that is input to this process immediately increases according to the accelerator depression, but is replaced by the upper limit guard value taupg that changes according to the gradually changing reflection amount taupgre, and the target throttle opening is Changes gradually. Therefore, it is possible to prevent the engine speed from rapidly increasing with the start of the engine based on a sudden change in the throttle opening.

If the accelerator is depressed before the brake is released, the target throttle opening temporarily changes to a value corresponding to the amount of depression. The idling switch is turned off in response to depression of the accelerator. Also, the signal wstp is ON because the brake is depressed
Therefore, the motor generator 26 has not started operation.

When the brake is released, the fuel cut is stopped, and the driving of the motor generator is started. Here, even if the accelerator pedal is depressed, the target throttle opening is guarded by the upper limit guard value, so it does not suddenly increase, and changes according to the reflection amount taupgre determined in the table. It increases according to the guard value.

As described above, according to the present embodiment, even if the accelerator is depressed before the brake is released, or even if the accelerator is depressed early after the brake is released, the upper limit guard value at which the target throttle opening gradually changes is maintained. It gradually changes. Therefore, it is possible to effectively prevent the engine speed from rapidly increasing when the engine is started.

[0049]

As described above, according to the present invention,
During motoring of the internal combustion engine by the electric motor, the throttle opening is gradually changed until the throttle opening corresponding to the depression of the accelerator is reached. Thus, when the accelerator is depressed beforehand at the start of motoring by the electric motor or when the accelerator is depressed immediately, it is possible to prevent a sudden start due to a sudden opening of the throttle.

Further, by changing the degree of gradually increasing the throttle opening based on the timing of depressing the accelerator pedal, the timing of depressing the accelerator pedal is earlier and the rotation of the internal combustion engine due to motoring is still increasing. When there is no throttle, by setting the degree of gradually increasing the throttle opening small, it is possible to more effectively prevent a sudden start due to a sudden opening of the throttle.

Further, by changing the degree of gradually increasing the throttle opening based on the amount of depression of the accelerator pedal, when the driver depresses the accelerator greatly, the throttle opening changes earlier. This makes the driver less uncomfortable.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an apparatus according to an embodiment.

FIG. 2 is a flowchart illustrating an operation.

FIG. 3 is a timing chart illustrating an operation.

[Explanation of symbols]

2 engine, 2b intake pipe, 2c throttle valve, 46 ECU, 50 fuel injection valve.

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Claims (3)

[Claims] 1. An internal combustion engine having an electric motor connected to a drive shaft of the internal combustion engine, wherein the internal combustion engine is started by motoring the internal combustion engine by driving the electric motor in a state where the torque of the internal combustion engine can be transmitted to driving wheels. In a start control device for an internal combustion engine to be controlled, a depression detecting means for detecting depression of an accelerator pedal; and gradually increasing the throttle opening to a throttle opening corresponding to the depression of the accelerator pedal during motoring by driving the electric motor. A start control device for an internal combustion engine, comprising: throttle opening control means. 2. The internal combustion engine according to claim 1, wherein the throttle opening control means changes the degree of gradually increasing the throttle opening based on the timing of depressing an accelerator pedal. Start guidance control device. 3. The internal combustion engine according to claim 1, wherein the throttle opening control means changes the degree of gradually increasing the throttle opening based on the amount of depression of an accelerator pedal. Engine start control.