JP2001020787A - Control device for internal combustion engine - Google Patents

Abstract

(57) [Problem] To provide a control device for an internal combustion engine that prevents sudden torque generation at the time of restart and does not give a shock to a vehicle body and an occupant. SOLUTION: An intake manifold air amount calculation unit 4 integrates an intake air flow rate measured by an air flow meter 2 at a timing instructed by a timer unit 3 to calculate a manifold air amount Cm. The restart required air amount calculation unit 5 calculates the outside air temperature T
The required air amount Qd required for restarting is calculated based on a and the cooling water temperature Te. The throttle opening calculator 7 calculates the throttle opening based on the manifold air amount Cm and the required air amount Qd, and controls the electronically controlled throttle 8 at the time of restart.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control apparatus for an internal combustion engine that automatically performs idle stop, and more particularly to a control apparatus for an internal combustion engine in which startability at the time of restart is improved and shock at the time of restart is reduced. Related to the device.

[0002]

2. Description of the Related Art In recent years, in order to reduce exhaust gas, reduce carbon dioxide emission, and reduce fuel consumption, an idle stop movement for stopping the engine while the vehicle is stopped has been performed. Also, in order to reduce the burden of the driver's idle stop operation during frequent stoppages due to traffic jams or traffic lights, vehicles equipped with an idle stop function that detects the idle state and automatically stops and restarts the engine have been considered. I have.

In an automobile having such an idle stop function, the time elapsed from the stop of the engine to the restart is frequently short. In order to improve the restartability of such an internal combustion engine, a first prior art described in Japanese Patent Application Laid-Open No. 7-224712 is known. According to the first prior art, in an internal combustion engine using an air flow meter equipped with a heating resistor as an intake air amount sensor, the heating resistor is energized prior to engine start, and energization is continued until a predetermined time elapses after the engine is stopped. Is what you do.

A technique for improving the restartability of an internal combustion engine provided with a variable valve timing mechanism is disclosed in Japanese Unexamined Patent Application Publication No.
A second prior art described in U.S. Pat. No. 2,610,027 is known. In the second prior art, an auxiliary power switch that is closed when a main power switch is opened is provided, and after the main power is turned off, an idle speed control valve (ISCV) is forcibly fully opened in preparation for restart. In addition, the valve timing is set to a valve overlap period suitable for starting the engine.

[0005]

However, in the above prior art, the throttle opening at the start is always set according to the engine temperature such as the cooling water temperature regardless of the state in the intake manifold. There has been a problem that a sudden torque is generated and a shock is applied to the vehicle body and the occupant.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a control device for an internal combustion engine which prevents sudden torque generation at the time of restart and does not give a shock to a vehicle body and an occupant.

[0007]

According to the first aspect of the present invention,
In order to achieve the above object, an internal combustion engine having an idle stop function for automatically stopping the engine when a predetermined idle condition is satisfied and automatically restarting the engine when a predetermined restart condition is satisfied A control device for controlling the amount of air taken by the engine, a condition estimation device for estimating a condition in the intake manifold during idle stop, and a required air amount for restarting the engine. And a degree-of-opening calculating means for calculating the degree of opening of the intake air amount control means according to the state of the inside of the manifold and the required amount of air.

According to a second aspect of the present invention, there is provided a control apparatus for an internal combustion engine according to the first aspect, wherein the above object is achieved.
The state-in-manifold state estimating means is a storage means for storing the intake-manifold-internal-pressure immediately before the idle-stop, the stored intake-manifold-internal-pressure as an initial value, and the idle-stop duration as an integration time. And calculating means for calculating.

According to a third aspect of the present invention, there is provided a control apparatus for an internal combustion engine according to the first aspect, wherein the above object is achieved.
The gist of the invention is that the manifold internal state estimating means is an intake pressure sensor provided in an intake manifold section.

According to a fourth aspect of the present invention, in order to achieve the above object, in the control apparatus for an internal combustion engine according to any one of the first to third aspects, the required air amount calculating means includes an outside air temperature and an outside air temperature. The gist is to obtain a required air amount by indexing a table stored in advance based on the engine temperature.

According to a fifth aspect of the present invention, there is provided a control apparatus for an internal combustion engine according to any one of the first to fourth aspects, wherein the intake air amount control means is an electronically controlled throttle. The gist of the invention is that the inside-manifold state estimating means integrates the air flowing from the electronic control throttle to calculate the total gas amount in the intake manifold.

According to a sixth aspect of the present invention, in order to achieve the above object, in the control apparatus for an internal combustion engine according to any one of the first to fourth aspects, the intake air amount control means includes an intake valve. The gist of the invention is a valve timing control means for controlling the intake air amount by changing the opening / closing timing.

[0013]

According to the first aspect of the present invention, there is provided a control device for an internal combustion engine having an idle stop function.
Based on the state in the intake manifold during the idle stop estimated by the state estimation means in the manifold and the required air amount at the time of restarting the engine calculated by the required air amount calculation means, the opening degree calculation means operates the intake air amount control means. Since the opening degree is calculated, the opening degree of the intake air amount control means can be optimally controlled at the time of restart, preventing a sudden torque from being generated at the time of restart, and giving a shock to the vehicle body and the occupant. This has the effect of eliminating things.

According to the second aspect of the present invention, the first aspect is provided.
In addition to the effects of the described invention, the manifold internal state estimating means includes a storage means for storing an intake manifold internal pressure immediately before an idle stop, and the stored intake manifold internal pressure as an initial value, and a duration of the idle stop. And calculating means for calculating a change in the intake manifold pressure with the integral time as an integration time, so that the change in the intake manifold pressure can be calculated with high accuracy in accordance with the lapse of time after the idle stop. Can be.

According to the third aspect of the present invention, there is provided the first aspect.
In addition to the effects of the invention described in the above, since the inside-manifold state estimating means is an intake pressure sensor provided in the intake manifold section, the inside-manifold state can be accurately determined by directly measuring a pressure change in the intake manifold. Can be estimated.

According to the fourth aspect of the present invention, the first aspect is provided.
In addition to the effect of the third aspect of the invention, the required air amount calculating means obtains the required air amount by indexing a table stored in advance based on the outside air temperature and the engine temperature. The required air amount can be obtained in a short time without performing complicated calculations.

According to the invention described in claim 5, claim 1 is provided.
In addition to the effects of the invention described in claim 4, the intake air amount control means is an electronic control throttle, and the required air amount calculation means performs an integral calculation of the air flowing from the electronic control throttle to obtain an intake manifold. Since the total gas amount in the intake manifold is calculated, a change in the intake manifold internal pressure can be calculated with high accuracy in accordance with the lapse of time after the idle stop.

According to the sixth aspect of the present invention, a first aspect is provided.
In addition to the effect of the invention described in claim 4, the intake air amount control means is a valve timing control means for controlling the intake air amount by changing the opening / closing timing of the intake valve. The invention can also be applied to an internal combustion engine that controls the intake air amount by opening and closing an intake valve at an arbitrary timing.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a first embodiment of a control device for an internal combustion engine according to the present invention.

In FIG. 1, a control unit 1 includes an air flow meter 2 for detecting an intake air amount of an engine, a timer unit 3 for generating a clock signal at regular time intervals, and a timer for counting time after the engine is stopped as well as during engine operation. An intake manifold air amount calculator 4 for calculating an air amount in the intake manifold according to a time signal from the unit 3; a restart required air amount calculator 5 for calculating a required air amount at the time of restart; and a throttle opening And an electronically controlled throttle 8 disposed downstream of the air flow meter 2 to control the amount of intake air.

The air flow meter 2 preferably employs a method capable of measuring a low flow rate, for example, a hot wire type, among various types of air flow meters. The measurement signal of this air flow meter is defined as Qa.

The timer unit 3 oscillates a natural frequency using a quartz oscillator or the like, divides the natural frequency, and generates a time signal t having a fixed cycle of, for example, every 1 msec.

The intake manifold air amount calculation unit 4 calculates the air amount in the manifold which is in the intake manifold state during the operation of the engine and after the engine is stopped, and in accordance with a fixed period time signal t from the timer unit 3. , The air flow in and out of the manifold is calculated, and the calculated air value Cm is sequentially updated using the calculated value.

The restart required air amount calculating unit 5 calculates the required air amount based on the outside air temperature Ta and the cooling water temperature Te as the engine temperature.
Calculate the amount of air required for the engine to restart. Although this calculation may be performed according to an approximate calculation formula, in the present embodiment, a required air amount map 6 is provided inside the restart required air amount calculation unit 5, and two-dimensional variables of Ta and Te are used. The required air amount Qd is obtained by indexing the map.

The throttle opening calculation unit 7 calculates the required air amount Cd calculated by the intake manifold air amount calculation unit 4 and the required air amount Qd calculated by the restart required air amount calculation unit 5 based on the calculated intake air amount calculation unit 4. For example, the opening degree of the electronic control throttle 8 at the time of restart is calculated with reference to a map stored in advance.

Next, referring to the flowchart of FIG.
An operation flow of the present embodiment will be described. Note that the flowchart shown in FIG. 2 is an operation for each time signal t generated by the timer unit 3, and the air flow meter 2
It may be considered as a subroutine in a case where components other than the electronic control throttle 8 are constituted by a microcomputer or the like.

First, it is determined whether or not the vehicle is idling (step 10, hereinafter, step is abbreviated as S).

Here, the idle stop will be supplementarily described. The idle stop condition for automatically stopping the engine as determined by the control device is, for example, when the engine warm-up is completed and the storage battery does not need charging, the driver releases the foot from the accelerator pedal and releases the brake pedal. This is when all the conditions such as the stepping state, the vehicle speed has become zero, and the gear position is N or D are satisfied. The control device of the internal combustion engine performs fuel injection and ignition stop when the idle stop condition is satisfied,
The engine is shut down automatically.

When the driver changes the brake pedal from the brake pedal to the accelerator pedal, the side brake is released, and if the gear position is N or D, the control device determines that the restart condition is satisfied and starts the starter motor. The engine is automatically restarted by driving and performing fuel injection and ignition.

If it is determined in S10 that the engine is not idling, the air flow rate Qa is measured by the air flow meter (S12), and the amount of air Cc flowing from the intake manifold to the cylinder is calculated (S14). Next, the previous time signal t
The previous intake manifold air volume Cm calculated in synchronization with
By adding [Qa · Δt−Cc] to (n−1), the current intake manifold air amount Cm (n) is obtained (S16), and the process returns to the main routine. here,
Δt is the time from time n-1 to time n, that is, the interval of the time signal t generated by the timer unit 3.

If it is determined in S10 that the engine is idling stop, it is determined whether a predetermined restart condition for restarting the engine is satisfied (S18). If the engine is not restarted, the engine is moved into the intake manifold. Is measured (S20), and Qa is added to the previous intake manifold air amount Cm (n-1) calculated in synchronization with the previous time signal t.
By adding Δt, the current intake manifold air amount Cm (n) is obtained (S22), the elapsed time after the idle stop is updated (S24), and the process returns to the main routine.

If it is determined in S18 that the restart condition is satisfied, the outside air temperature Ta is measured (S26), and the cooling water temperature T is measured.
e is measured (S28), and the required air amount Qd is calculated using Ta and Te (S30).

Next, the throttle opening at restart is calculated using the calculated required air amount Qd and the air amount Cm in the intake manifold calculated up to the previous time (S32),
The electronic control throttle is set to the throttle opening (S34), and the engine is started (S36).

Thus, the state of the intake manifold is calculated even after the engine is stopped, and the opening of the electronic control throttle can be controlled in accordance with the state of the intake manifold when the engine is restarted. Is generated and good restartability is ensured, and an excessive torque is not suddenly generated and does not impact the vehicle and the occupant.

FIG. 3 shows an intake air amount calculation section 4 in the intake manifold.
FIG. 3 is an explanatory diagram of an internal model of an intake system used for calculation.
In FIG. 3, an air flow meter (A
An electronic control throttle 8 is provided downstream of the FM) 2. An intake manifold section 20 is provided downstream of the electronic control throttle 8, and a cylinder section 22 is provided via an intake valve 21.

The air flow rate in the AFM section is defined as Qa [kg / h]. The pressure in the manifold section is Pm [Pa] and the volume is Vm
[M ³ ], air mass is Cm [g], temperature is Tm [°
K]. The cylinder pressure is Pc [Pa], the volume is Vc [m ³ ], the air mass is Cc [g], and the temperature is Tc
[° K], and the ratio of fresh air in the cylinder is η.

The air amount Cm (n) in the intake manifold is:
It is represented by the following equation (1).

Cm (n) = Cm (n−1) + Qa (n) · Δt−Cc (n) (1) where Qa (n) · Δt is the amount of air flowing into the manifold, Cc (n) is the amount of air flowing out of the manifold.

Further, the gas constant is R and the engine speed is N
e, manifold temperature = cylinder temperature (Pm = P
c), manifold pressure = cylinder pressure (Tm = T
Assuming that c), Cc is expressed by the following equation (2).

Cc = η · Pm · Vc / (R · Tm) / Ne (2) FIG. 4 is a signal diagram showing the calculation contents of the air amount in the intake manifold shown by the equation (1). As the input signal, the air flow rate Qa of the AFM section, the approximate air flow rate QH0,
The engine speed Ne is the cylinder volume Vc. The output signal is the manifold air amount Cm.

The approximate value QH0 of the air flow rate is determined by the engine speed Ne.
Is an approximate value of the intake air flow rate obtained from a throttle opening (not shown), and Ktrm is obtained by indexing a Ktrm map, which is a correction coefficient map, using QH0 and Ne. Then, the air flow rate measured by the AFM unit is multiplied by Ktrm,
I get the correct air flow. It is known that the characteristics of the hot-wire air flow meter used here fluctuate due to intake pulsation. To obtain as flat an open-loop air-fuel ratio control characteristic as possible, the measured value is corrected by Ktrm. It is carried out.

Next, after changing the unit of Qa, 1 msec
Is performed to obtain the amount Ca of air flowing into the manifold. On the other hand, the cylinder pressure Pc =
By multiplying by Pm, an outflow air amount Cc from the manifold is obtained. Then, Cm (n-1) is given by Ca = Qa.
By subtracting Cc from the value obtained by adding (n) · Δt, an updated manifold air amount Cm (n) is obtained.

FIG. 5 shows the throttle opening at the time of restart with respect to the time from engine stop to restart in this embodiment. For example, as shown in FIG.
When the engine is stopped, the pressure in the intake manifold is -200mmHg
If it is above, at the time of restart immediately after the stop, the throttle opening becomes 70% (0.7) of the full opening (1.0), and as the time until the restart elapses, the throttle opening at the time of restarting Becomes smaller, and at the time of restarting after about one second, the throttle opening becomes substantially constant at 0.5.

As shown in FIG. 5B, when the intake manifold internal pressure is -200 mmHg or less when the engine is stopped, the throttle opening becomes almost fully open (1.0) when the engine is restarted immediately after the stop. As the time until the restart elapses, the throttle opening at the time of restarting becomes smaller, and at the time of restarting after about 3 seconds, the throttle opening becomes approximately 0.
5 is constant.

In the present embodiment, the air amount in the intake manifold is calculated as the means for estimating the state in the intake manifold. However, the present invention is not limited to this, and an intake pressure sensor is provided in the intake manifold instead of the air flow meter. Alternatively, the air amount may be calculated from the pressure in the intake manifold, and the throttle opening may be calculated based on the calculated value and the restart-time required air amount.

In this case, the intake pressure sensor value when the engine is stopped is temporarily stored as an initial value, and the air flow rate corresponding to the difference between the atmospheric pressure, which can be regarded as substantially constant, and the intake manifold pressure leaks from the throttle valve. The amount of air in the manifold may be integrated and calculated.

FIG. 6 is a block diagram showing the configuration of a second embodiment of the control device for an internal combustion engine according to the present invention. In FIG. 6, a control device 101 includes an air flow meter 2 for detecting an intake air amount of an engine, a timer 3 for generating a clock signal at regular time intervals, and a timer 3 even after the engine is stopped as well as during engine operation. An air amount calculation unit 4 in the intake manifold that calculates the air amount in the intake manifold according to the timing signal of
A restart required air amount calculating unit 5 for calculating a required air amount at the time of restart, an intake / exhaust valve opening / closing timing calculating unit 10 for calculating the opening / closing timing of an electromagnetically driven intake / exhaust valve, and an electromagnetically driven intake / exhaust valve 11 are provided. Have.

The control device 101 of the present embodiment is applied to an internal combustion engine having an electromagnetically driven intake / exhaust valve, and is a component of the first embodiment shown in FIG. An intake / exhaust valve opening / closing timing calculator 10 and an electromagnetically driven intake / exhaust valve 11 are provided instead of the opening degree calculator 7 and the electronic control throttle 8. Other configurations are the same as those of the first embodiment, and are denoted by the same reference numerals.

In an internal combustion engine having an electromagnetically driven intake / exhaust valve, the amount of intake air can be controlled by controlling the opening / closing timing of the intake / exhaust valve. It is almost open.

The operation of this embodiment is the same as that of the first embodiment, except that the opening / closing valve opening / closing timing is calculated instead of the throttle opening calculation. That is, in the first embodiment, when the calculated value of the throttle valve opening degree is fully opened, in the present embodiment, the opening and closing timing of the intake valve is opened at the timing at which the maximum intake air amount is obtained, for example, near the top dead center, Close timing near the dead center.

When the throttle valve is throttled in the first embodiment, the intake valve is controlled to close early or to close late beyond the bottom dead center in accordance with the throttle amount. By controlling the opening / closing timing of the intake valve in this manner, an optimal amount of air can always be sucked into the cylinder regardless of the time from engine stop to restart, ensuring good restartability, This prevents abrupt torque generation at the time of restart and eliminates impact on the vehicle and the occupant.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a first embodiment of a control device for an internal combustion engine according to the present invention.

FIG. 2 is a flowchart illustrating an operation of the first embodiment.

FIG. 3 is an explanatory diagram of an internal model of an intake system calculated by an intake manifold internal air amount calculation unit.

FIG. 4 is a signal diagram showing calculation contents of an air amount calculation section in the intake manifold.

FIG. 5 is a graph showing an example of a throttle opening degree with respect to an elapsed time after an engine stop.

FIG. 6 is a block diagram illustrating a configuration of a second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control device 2 air flow meter 3 timer unit 4 air amount calculation unit in intake manifold 5 required air amount calculation unit at restart 6 required air amount map 7 throttle opening degree calculation unit 8 electronic control throttle

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F02D 13/02 F02D 13/02 D 17/00 17/00 Q 41/04 330 41/04 330H 41/18 41/18 B 43/00 301 43/00 301A 301H 301K 301Z 301V 45/00 310 45/00 310B 310G (72) Inventor Ichiro Fujimori F-term in Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa ) 3G065 CA00 DA04 EA01 GA01 GA05 GA09 GA10 GA27 KA02 3G084 BA05 BA13 BA16 BA23 BA28 CA01 CA07 DA06 DA11 DA15 EA07 EA11 EB06 EB09 EB12 EC01 EC03 FA02 FA03 FA06 FA08 FA10 FA20 3G092 AA11 AC03 BA01 CB03 EB10 DA03 CB10 EC09 FA04 FA32 GA01 HA01Z HA04Z HA05Z HA06X HE08Z 3G301 JA04 JA18 KA04 KA07 KA26 KA28 LA00 LA01 LA07 MA11 MA24 NA04 NC01 NC04 ND02 ND04 NE23 PA04Z PA07Z PA10Z PE08Z PF03Z PF05Z PF07Z PF10Z PG01Z

Claims (6)

[Claims] 1. Control of an internal combustion engine having an idle stop function for automatically stopping an engine when a predetermined idle condition is satisfied and automatically restarting the engine when a predetermined restart condition is satisfied. An intake air amount control means for controlling an amount of air taken into the engine, a manifold state estimation means for estimating a state in the intake manifold during an idle stop, and a required air amount for restarting the engine A required air amount calculating means, and an opening degree calculating means for calculating an opening degree of the intake air amount controlling means in accordance with the state in the manifold and the required air amount. apparatus. 2. The manifold state estimating means includes: a storage means for storing an intake manifold pressure immediately before an idle stop; an initial value of the stored intake manifold pressure; and an idle stop duration as an integration time. The control device for an internal combustion engine according to claim 1, further comprising: calculation means for calculating an intake manifold internal pressure. 3. The control device for an internal combustion engine according to claim 1, wherein said manifold internal state estimating means is an intake pressure sensor provided in an intake manifold section. 4. The required air amount calculating means according to claim 1, wherein the required air amount calculating means obtains the required air amount by indexing a table stored in advance based on the outside air temperature and the engine temperature. The control device for an internal combustion engine according to claim 1. 5. The intake air amount control means is an electronically controlled throttle, and the manifold internal state estimation means integrates the air flowing from the electronically controlled throttle to calculate the total gas amount in the intake manifold. The control device for an internal combustion engine according to any one of claims 1 to 4, characterized in that: 6. The intake air amount control means is a valve timing control means for controlling an intake air amount by changing an opening / closing timing of an intake valve.
The control device for an internal combustion engine according to claim 4.