JP3360127B2 - Engine intake air control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake air amount control device for an engine.

[0002]

2. Description of the Related Art In an engine, an effective compression ratio is made smaller than an effective expansion ratio by setting an intake valve closing timing to a late intake closing later than a normal setting or an intake valve closing timing to an early intake closing earlier than a normal setting. Attempts have been made to improve fuel efficiency. The engine described in Japanese Patent Application Laid-Open No. 63-239312 has a valve timing that is set to a late intake closing. In this case, the engine is provided with a supercharger, and the decrease in the charging efficiency caused by the late closing of the intake air is supercharged. To make up for it.

[0003]

When the valve timing of the engine is set to the late intake closing or the early intake closing as described above, the decrease in the charging efficiency can be compensated for by supercharging as described above. Further, in such an engine in which the valve timing is set to the late intake closing or the early intake closing, the amount of air at the time of starting (at the time of cranking) tends to be insufficient, and particularly at the time of cold starting, the mechanical resistance is large. Sometimes the problem of the engine not running occurs. Therefore, in such an engine, it is conceivable to supply air sufficiently into the cylinder by performing supercharging even at the time of starting. However, if supercharging is actually performed at the start of an engine with the intake late-closed or the intake early-closed as described above, the cranking itself becomes easy, but the startability deteriorates. Is newly generated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has been made in consideration of the above-described problems. The purpose is to prevent the deterioration of.

[0005]

In order to improve fuel efficiency, the intake is closed late or the intake is closed early, and when a supercharging device is provided to perform supercharging even at the time of starting, the turbocharger is used for supercharging. During the ranking, the pressure in the intake passage is high, so that when the intake valve is opened, the flow velocity of the air flowing into the cylinder is large, so that the fuel is scattered and the scattered fuel adheres to the ignition plug. This is particularly remarkable in an engine that performs control to increase the amount of air using an ISC (idle speed control) bypass passage in order to improve the rotational speed after starting. The present invention is based on the finding that the cause of the deterioration of the startability is due to the adhesion of the fuel to the spark plug due to the scattering of the fuel, and the valve timing for making the effective compression ratio smaller than the effective expansion ratio An engine having a set intake / exhaust valve device, a supercharging device, and an engine including supercharging control means for controlling the supercharging device so as to perform supercharging in a predetermined operation region including the time of starting the engine . En
A starting intake air amount suppressing means for suppressing an increase in the intake air amount in a region until the gin rotational speed reaches the set rotational speed ,
When the engine temperature is low, the set rotation speed is the engine temperature.
The above problem was solved by configuring the intake air amount control device so that the intake air amount control device was set to the high rotation side when the degree was high .

The starting intake air amount suppressing means is, for example, a throttle.
Start by limiting the amount of bypass air that bypasses the throttle valve
At times, an increase in the amount of intake air is suppressed.

[0007]

According to the present invention, in an engine in which the effective compression ratio is set to a valve timing that is smaller than the effective expansion ratio as the intake late closing or the intake early closing and the supercharging is performed even at the start, In the region where supercharging is performed, the increase in the intake air amount is suppressed by limiting the bypass air amount and the like. As a result, a rise in pressure in the intake passage due to supercharging at the time of starting is suppressed, whereby a rise in the flow velocity of air flowing into the cylinder at the beginning of the opening operation of the intake valve is suppressed, and adhesion of fuel to the spark plug due to scattering of fuel is suppressed. Is prevented.

Further, the intake air amount suppression region at the time of starting is defined by the engine speed, and when the set engine speed is low, the engine speed is set to be higher than when the engine temperature is high. As a result, at low temperatures, where fuel adhesion is particularly prominent because the engine temperature is low and the amount of fuel increase is large, the increase in intake air volume at startup is sufficiently suppressed to prevent fuel scattering. On the other hand,
When the engine temperature is high and the rate of fuel increase is small, fuel adhesion is not so noticeable.At high temperatures, the suppression area for the amount of intake air is limited, and the rotational speed after startup increases. Get better.

[0009]

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

FIG. 1 is an overall system diagram of an embodiment of the present invention. The engine 1 of this embodiment is a V-type multi-cylinder, and the independent intake passages 2a and 2b of the cylinders in the left and right banks are formed so as to branch from surge tanks 3A and 3B which are independent for each bank. In addition, each surge tank 3A, 3B
Is connected to one upstream intake passage 5 connected to the air cleaner 4 via branch passages 6A and 6B, respectively. An air flow sensor 7 is disposed downstream of the air cleaner 4 in the upstream intake passage 5, a resonator 8 is provided downstream thereof, a throttle valve 9 is provided downstream of the resonator 8, and a mechanical valve is further downstream thereof. Feeder 1
0 is set. Further, a supercharger bypass passage 11 that communicates between the upstream side of the supercharger 10 and the downstream side of the supercharger 10 of the upstream side intake passage 5 so as to bypass the mechanical supercharger 10 with respect to the upstream side intake passage 5 is provided. A bypass valve (AB) provided with a diaphragm type actuator 12 in the middle of the passage
V) 13 is installed.

The actuator 12 has an atmosphere chamber 12b and an operating negative pressure chamber 12c partitioned by a diaphragm 12a.
A valve shaft of the bypass valve 13 is connected to the side 2b, and a spring 14 is disposed on the side of the operation negative pressure chamber 12c so as to constantly bias the diaphragm 12a in the valve closing direction. Further, an operation negative pressure introduction passage 15 for introducing an operation negative pressure into the operation negative pressure chamber 12c of the actuator 12 is provided, and an upstream of the operation negative pressure introduction passage 15 from a negative pressure source (vacuum pump) not shown. A first duty solenoid valve 16A for controlling the introduction of a negative pressure and a second duty solenoid valve 16B for controlling the introduction of the atmospheric pressure upstream of the throttle from the resonator are arranged.

Further, intercoolers 17A and 17B are provided in branch passages 6A and 6B connected to the inlet sides of the surge tanks 3A and 3B, respectively. Then, the supercharger bypass passage 11, which bypasses the mechanical supercharger 10, branches off from the downstream side of the bypass valve 13, and the branch passages 6A,
Intercooler bypass passages 18A and 18B communicating with the downstream side of the intercoolers 17A and 17B of the 6B are provided. In the vicinity, an intercooler bypass valve 19 for switching the flow of the bypass air between the intercoolers 17A and 17B and the intercooler bypass passages 18A and 18B is provided.
The intercooler bypass valve 19 is driven to be opened and closed by a diaphragm type actuator 20,
It is configured to normally open and close when a negative pressure is introduced into the actuator 20 via the three-way solenoid valve 21.

When the engine load is low, the bypass valve 13 provided in the turbocharger bypass passage 11 is opened, and the intercooler bypass valve 19 is opened. At this time,
The air from the air cleaner 4 bypasses the mechanical supercharger 10 and further bypasses the intercoolers 17A, 17B to flow to the surge tanks 3A, 3B of each bank. When the engine is under a high load, the bypass valve 13 is closed, and the intercooler bypass valve 19 is closed. At this time, the air that has entered from the air cleaner 4 flows into the mechanical supercharger 10, is pressurized, and is sent to the surge tanks 3A, 3B of each bank through the intercoolers 17A, 17B.

A first and second two throttle bypass passages 2 are provided in the upstream intake passage 5 so as to bypass the throttle valve 9 and communicate the resonator 8 and the upstream of the supercharger 10.
2, 23 are provided. In the first throttle bypass passage 22, a duty-controlled solenoid air valve (ISC valve) 24 and a wax-type air valve 25 that opens when the engine coolant temperature is low and closes at a set temperature (for example, 80 ° C.) or more are provided. A bypass air control valve 26 arranged in parallel is provided. The second throttle bypass passage 23 has an idle-up solenoid valve 2 that opens when an air conditioner, power steering, or the like operates.
7 are provided.

In each cylinder of the engine 1, an intake valve 29 and an exhaust valve 30 are provided in each combustion chamber 28, and an ignition device 31 and a fuel injection valve for supplying fuel to the independent intake passages 2A and 2B are provided. 32 are provided.

The engine 1 has an engine control unit 33 composed of a microcomputer. Various signals such as an engine speed signal, an engine water temperature signal, a boost pressure signal, a throttle opening signal, a starter switch signal and the like are input in addition to the intake air amount signal from the air flow sensor 7, and the fuel injection amount and the ignition timing Is performed, ABV control is performed by the first and second duty solenoid valves 16A and 16B, and the three-way solenoid valve 21 is controlled.
ISC valve 24, idle up solenoid valve 27
Are performed.

The valve timing of the engine 1 is 70 ° after the bottom dead center when the intake valve closing timing is the crank angle,
The intake late closing setting is set so that the effective compression ratio is smaller than the effective expansion ratio.

The ABV (bypass valve) 13 basically has an intake pressure (boost pressure) of -200 m as shown in FIG.
It is controlled to be gradually closed at mHg or more and fully closed at +200 mmHg. Further, the ABV 13 is forcibly closed at cold start regardless of the intake pressure.

FIG. 3 is a flowchart for executing the ABV control. This flowchart is performed in steps S101 to S10.
When starting, various signals are read in S101. Then, in S102, the intake pressure P becomes-
Checking whether the pressure is 200 mmHg or more, the intake pressure P is -2.
If it is not less than 00 mmHg, the routine proceeds to S103, where normal ABV control is performed based on a characteristic map using the engine speed and the throttle opening as parameters.

In S102, the intake pressure P is -200 mmHg
If it is lower, the process proceeds to S104, and it is determined whether or not the engine water temperature is cold, for example, at 0 ° C. or less. If it is cold, it is determined whether or not the starter switch is ON in S105,
If the starter switch is ON, it is further determined in S106 whether or not the engine speed Ne is lower than a predetermined speed Nk as the complete explosion determination speed. And S10
If all of the determinations in 4 to S106 are YES, S107
Then, ABV is fully closed.

In S102, the intake pressure P becomes -200 m.
If it is determined that the pressure is lower than mHg, and if the determination in any of S104 to S106 is NO, A is determined in S108.
Open BV.

In this embodiment, the idle-up solenoid valve 27 is closed at the time of starting, and the ISC valve 24 is closed until the engine speed reaches the complete explosion determination speed Nk set according to the water temperature. .

FIG. 4 is a table of the complete explosion determination rotation speed Nk set according to the water temperature. As shown here, the complete explosion determination rotation speed Nk is determined by increasing the engine water temperature from −20 ° C. to +4.
In a temperature range of 0 ° C., for example, at 500 rpm, -20 ° C.
On the lower temperature side, it is set higher, for example, 600 rpm. On the higher temperature side than + 40 ° C, ISC valve 2
The setting of the complete explosion determination rotation speed Nk is gradually reduced so as to limit the region in which 4 is closed to the low rotation side. And +80 ゜ C
In the above, the setting is such that the ISC valve 24 is not closed at all even at the time of starting.

FIG. 5 is a flowchart for executing the ISC valve control. This flowchart is from S201 to S201.
It consists of the steps of S212, and when it starts, it goes to S20
1 reads various signals. Then, in S202, it is determined whether the starter switch is ON or not. If the starter switch is ON, the complete explosion determination rotation speed Nk according to the engine coolant temperature is set in S203 using the table in FIG. Then, it is determined in S204 whether the engine speed Ne is lower than the complete explosion determination rotation speed Nk. If Ne is lower than Nk, the ISC control amount is set to 0 (zero) in S205, and the fully closed signal is set to ISC in S206. Output to valve.

If the starter switch is not ON in S202, it is determined whether or not the engine is idling in S207. If the engine is idling, the target idling speed N ₀ according to the water temperature is set in S208. Then, set the ISC basic control amount G _B corresponding to the target idle speed N ₀ in S209, it obtains the feedback correction amount G _FB based on the deviation between the actual engine speed and the target idle speed in S210, in S211 final control amount G of ISC by correcting the basic control amount G _B by the feedback correction amount G _FB
To determine. Then, in S206, an ISC control signal corresponding to the final control amount G is output to the ISC valve.

If it is determined in step S207 that the vehicle is not idling, the process proceeds to step S212, where the ISC control amount is set to a fixed value G according to the operating state, and output to the ISC valve in step S206.

Even if the starter switch is ON,
If the engine speed Ne is equal to or greater than the complete explosion determination speed Nk in the determination in S204, the ISC valve is stopped from being closed, and the process proceeds to S207 to perform normal ISC control.

In the above-described embodiment, the intake late closing is specifically described in which the intake valve closing timing is 70 ° after the bottom dead center. However, the present invention is not limited to this. Further, the valve timing may be a setting of early intake closing.

In the above embodiment, the ISC valve is forcibly closed to suppress the amount of intake air when the engine is started. However, the intake air may be adjusted by adjusting the supercharging pressure. It is also possible to control the amount.

The setting of the cold determination water temperature, the complete explosion determination rotation speed, and the like is not limited to the above embodiment.

[0031]

As described above, the present invention suppresses an increase in the air flow velocity in the early stage of the opening operation of the intake valve due to supercharging at the start of the engine with the intake late closing or the early intake closing. Further, it is possible to prevent the fuel from scattering and adhering to the ignition plug. In addition, by restricting the amount of intake air at the time of startup to a region where the lower the water temperature does not reach the set rotation speed set on the high rotation side, it is possible to prevent fuel from adhering to the ignition plug at a low temperature and at a high temperature. It is possible to ensure a good rotational speed after starting.

[Brief description of the drawings]

FIG. 1 is an overall system diagram of an embodiment of the present invention.

FIG. 2 is a characteristic diagram of ABV control according to one embodiment of the present invention.

FIG. 3 is a flowchart for executing ABV control according to one embodiment of the present invention;

FIG. 4 is a characteristic diagram of a complete explosion determination rotation speed in ISC valve control according to one embodiment of the present invention.

FIG. 5 is a flowchart for executing ISC valve control according to one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 engine 10 mechanical supercharger 13 bypass valve (ABV) 22 first throttle bypass passage 23 second throttle bypass passage 24 air valve (ISC valve) 25 air valve (wax type) 26 bypass air control valve 27 idle-up solenoid Valve 29 Intake valve 33 Engine control unit

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ identification code FI F02D 43/00 F02D 43/00 301Z 45/00 312 45/00 312Q (58) Investigated field (Int.Cl. ⁷ , DB name ) F02D 41/00-45/00 395

Claims (2)

(57) [Claims] An intake / exhaust valve device set at a valve timing for setting an effective compression ratio smaller than an effective expansion ratio, a supercharging device, and the supercharging so as to perform supercharging in a predetermined operation region including engine starting. In an engine equipped with supercharging control means for controlling the device, when the engine starts , the engine speed reaches the set speed.
A start-up intake air amount suppression means for suppressing an increase in the intake air amount in a region until the engine temperature is low.
An intake air amount control device for an engine, wherein the intake air amount control device is set to a high rotation side when the degree is high . 2. The intake air amount control of an engine according to claim 1, wherein the starting intake air amount suppressing means suppresses an increase in the intake air amount at the time of starting by limiting a bypass air amount bypassing a throttle valve. apparatus.