JPH04347338A - Intake system for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the combustion and improve the fuel consumption due to the abatement of pumping loss so sufficient enough by reducing any possible drop in a mixture temperature just before ignition. CONSTITUTION:In an engine driving area where a mixture temperature just before ignition goes down and thereby combustion is worsened because an intake control valve 11 is closed so earlier, valve closing timing is controlled to be delayed so as to get fuel cincumption minimized, while the opening of a throttle valve 13 is adated according to a valve closing timing delay value of the intake control valve 11.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for an internal combustion engine.

0002

[Prior Art] A single intake control valve that can open and close this intake pipe is provided downstream of a throttle valve in an intake pipe where each intake branch pipe connected to each cylinder joins, and each intake valve opens and closes. There is a known intake system for an internal combustion engine that controls the amount of air taken into a cylinder by opening an intake control valve for a predetermined period of time (Japanese Patent Laid-Open No. 62-276219). (see publication).

0003

In this intake system, when the intake air amount is controlled by fully opening the throttle valve and controlling the closing timing of the intake control valve,
Since throttling loss due to the throttle valve can be eliminated, pumping loss can be reduced.

However, in engine operating ranges where the amount of intake air is relatively small, the intake control valve is forced to close early, which increases the adiabatic expansion period, which reduces the actual compression period, leading to This results in a problem in that the mixture temperature in the engine decreases and combustion deteriorates. As a result, a problem arises in that fuel efficiency cannot be sufficiently improved by reducing pump loss.

[0005]

[Means for Solving the Problems] In order to solve the above problems, according to the present invention, an intake control valve capable of opening and closing the intake passage is provided in the intake passage between the throttle valve and the intake valve, and the intake valve is opened and closed. In an internal combustion engine, the amount of air taken into the cylinder is controlled by opening the intake control valve for a predetermined period and controlling the closing timing of the intake control valve. In engine operating ranges where the control valve is closed early, the air-fuel mixture temperature immediately before ignition decreases and combustion worsens, and the closing timing of the intake control valve is delayed. A control means is provided for controlling the opening degree of the throttle valve to be reduced in accordance with the amount of the throttle valve.

[0006]

[Operation] In engine operating ranges where the air-fuel mixture temperature immediately before ignition decreases and combustion deteriorates because the intake control valve is closed early, the intake control valve close timing is retarded and the intake control valve The opening degree of the throttle valve is reduced in accordance with the amount of retardation of the valve closing timing.

By retarding the closing timing of the intake control valve, it is possible to reduce the drop in air-fuel mixture temperature immediately before ignition. In addition, since the opening degree of the throttle valve is reduced according to the amount of retardation of the intake control valve closing timing,
It is possible to prevent the amount of intake air from increasing due to the retardation of the intake control valve closing timing.

[0008]

[Example] Figures 1 and 2 show one of the multi-cylinder gasoline engines.
Showing two cylinders.

Referring to FIGS. 1 and 2, 1 is a cylinder block, 2 is a cylinder head, 3 is a cylinder chamber, and 4 is a cylinder block.
is an intake port, 5 is an exhaust port, 6 is a pair of intake valves, 7
indicate a pair of exhaust valves, respectively. Intake port 4 is an intake branch pipe 8
It is connected to the surge tank 9 via. A fuel injection valve 10 for injecting fuel into the intake port 4 is arranged in the intake branch pipe 8 immediately in front of the intake port 4 . In the intake branch pipe 8 between the surge tank 9 and the fuel injection valve 10, an intake branch pipe 8 is provided.
An intake control valve 11 for opening and closing is arranged. The intake control valve 11 is driven and controlled by an actuator 12 provided below the intake control valve. A linkless throttle valve 13 is disposed within the intake pipe 14 upstream of the surge tank 9, and this linkless throttle valve 13 is driven by an actuator 15.

FIG. 3 shows a perspective view of the intake control valve 11. Referring to FIG. 3, the intake control valve 11 includes a valve body 11a,
Upper and lower disc-shaped parts 11b and 11c are formed at the upper and lower ends of the valve body 11a, respectively, and a valve shaft 11d extends downward from the lower disc-shaped part 11c and is connected to the actuator 12 (see FIG. 1). It is equipped with

FIG. 4 shows the open position (indicated by a solid line in the figure) and the closed position (indicated by a chain line in the figure) of the valve body 11a of the intake control valve 11. The cross-sectional shape of the valve body 11a is formed to gradually taper from the center toward both ends.

5 and 6, the actuator 12
The structure and operation of Referring to FIG. 5, the actuator 12 includes a rotatable cylindrical magnetic pole 12a connected to a valve shaft 11d (see FIG. 3), and first and second magnetic poles arranged on opposite sides of the cylindrical magnetic pole 12a. 12b,
12c, and third and fourth magnetic poles 1 disposed on opposite sides of the cylindrical magnetic pole 12a and spaced apart by 90 degrees from the first and second magnetic poles 12b and 12c, respectively.
2d and 12e. First, second, third, and fourth magnetic poles 12b, 12c, 1
2d and 12e are magnetized by energizing the coils, and the first magnetic pole 12b is always magnetized to the north pole and the second magnetic pole 12c is always magnetized to the south pole. The cylindrical magnetic pole 12a is S as shown in the figure.
It is magnetized into poles and north poles. When the intake control valve 11 is open, the third magnetic pole 12d is magnetized to the S pole, and the fourth magnetic pole 12e is magnetized to the N pole. As a result, the cylindrical magnetic pole 12
a, the N pole of the cylindrical magnetic pole 12a is the second and third magnetic pole 1
It stands still between 2c and 12d.

On the other hand, when the intake control valve 11 is closed, the third magnetic pole 12d becomes the N pole and the fourth magnetic pole 12d becomes the N pole, as shown in FIG.
The magnetic pole 12e is magnetized to the S pole. As a result, the cylindrical magnetic pole 12a rotates by 90 degrees clockwise in the figure, and comes to rest with the N pole of the cylindrical magnetic pole 12a positioned between the second and fourth magnetic poles 12c and 12e.

Referring again to FIG. 1, the electronic control unit 20 is comprised of a digital computer, which includes a ROM (Read Only Memory) 22, a RAM (Random Access Memory) 23, and a RAM (Random Access Memory) 23, which are interconnected by a bidirectional bus 21.
It includes a CPU (microprocessor) 24, an input port 25, and an output port 26.

A crank angle sensor 30 that generates an output pulse every time the crankshaft rotates a predetermined crank angle is connected to the input port 25. The engine speed is calculated based on the output pulse of the crank angle sensor 30. Also,
Amount of depression of the accelerator pedal 15 (hereinafter referred to as "accelerator opening degree")
An accelerator pedal sensor 31 is connected to the input port 25 via an AD converter 27.

On the other hand, the output port 26 is connected to the actuators 12 and 15 via corresponding drive circuits 28 and 29, respectively.

Next, control of the intake control valve 11 will be explained with reference to FIG. For example, the crank angle θ is set to 0 at compression top dead center, and increases toward the right in FIG. In FIG. 7, the throttle valve 13 is fully open, and the intake control valve 1
1 shows a case where the intake air amount is controlled by controlling only 1.

The intake control valve 11 is opened at θ1 before the intake valve 6 is opened, and closed at θ2. Here, θ1 is a fixed value, and θ2
increases as the engine load increases. In addition,
θ1 may be changed according to an increase in load. Since air flows into the cylinder chamber 3 only during the period when both the intake valve 6 and the intake control valve 11 are open, air can be supplied into the cylinder chamber 3 by controlling the closing timing θ2 of the intake control valve 11. The amount of air used can be controlled. By doing so, it is possible to eliminate the throttling loss caused by the throttle valve, thereby reducing the pumping loss.

However, in engine operating ranges where the amount of intake air is relatively small, the intake control valve is forced to close early, so the adiabatic expansion period increases, which reduces the actual compression period, leading to This results in a problem in that the mixture temperature in the engine decreases and combustion deteriorates. As a result, a problem arises in that fuel efficiency cannot be sufficiently improved by reducing pump loss.

Therefore, in this embodiment, in the engine operating region where the air-fuel mixture temperature immediately before ignition decreases and combustion deteriorates because the intake control valve is closed early, the intake air control valve is adjusted to minimize the fuel consumption. The closing timing of the control valve is retarded, and the opening degree of the throttle valve is reduced in accordance with the amount of retardation of the closing timing of the intake control valve.

FIG. 8 shows region I, which is an engine operating region in which the air-fuel mixture temperature immediately before ignition decreases and combustion deteriorates because the intake control valve 11 is closed early, and the engine speed Ne and the accelerator opening are It is shown based on the degree θA. Within this region I, the intake control valve closing timing and throttle valve opening are controlled to minimize fuel consumption. That is, the intake control valve closing timing is retarded, and at the same time, the throttle valve opening degree is reduced in accordance with the amount of retardation of the intake control valve closing timing.

In region II above region I, the throttle valve 13 is fully opened, and the intake control valve closing timing is controlled in this state.

FIG. 9 shows the intake control valve closing timing θ2 and the throttle valve opening θ so that the engine speed and engine load are constant in the engine operating state in region I of FIG.
It shows the change in fuel efficiency when T is changed.

Referring to FIG. 9, the intake control valve closing timing θ
2 and throttle valve opening θT, such as θ2a and θT1, fuel consumption can be minimized. This is due to the following reasons.

That is, the throttle valve opening θT is set to θT1
If it is made larger, the pump loss can be reduced, but the intake control valve closing timing θ2 becomes earlier, which worsens combustion and ultimately increases fuel consumption.

On the other hand, if the intake control valve closing timing θ is made later than θ2a in order to improve combustion, the throttle valve opening θT
As a result, pump loss increases, resulting in increased fuel consumption.

Therefore, in the engine operating region (region I) where the air-fuel mixture temperature immediately before ignition decreases and combustion deteriorates because the intake control valve 11 is closed early, the intake control valve closing timing θ2 is throttled. By retarding the closing timing of the intake control valve to θ2a from the closing timing of the intake control valve when the valve is fully open, and correspondingly reducing the throttle valve opening θT from fully open to θT1 so that the amount of intake air is constant, Fuel consumption can be minimized.

That is, by retarding the intake control valve closing timing θ2, it is possible to reduce the drop in the air-fuel mixture temperature immediately before ignition and improve combustion, and it is possible to sufficiently improve fuel efficiency by reducing pump loss. can.

Furthermore, since the opening degree of the throttle valve is reduced in accordance with the amount of retardation of the intake control valve closing timing, the engine output does not increase due to the retardation of the intake control valve closing timing.

FIG. 10 shows an example in which the intake control valve closing timing θ2 and the throttle valve opening θT are changed so that the engine speed and the engine load are constant in the engine operating state on the boundary line L in FIG. This shows the change in fuel consumption over time.

When the engine operating state is on the boundary line L, the fuel consumption is at its minimum when the throttle valve opening θT is fully open. Therefore, in this case, the throttle valve opening θT is fully opened and the intake air amount is controlled by controlling the intake control valve closing timing θ2.

[0032] Even when the engine operating state is within Region II, the fuel consumption is minimized when the throttle valve opening θT is fully open, so the throttle valve opening θT is set fully open and the intake control valve closing timing is controlled. The amount of intake air is controlled by

FIG. 11 shows a routine for calculating the intake control valve closing timing θ2 and the throttle valve opening θT. This routine is executed by an interrupt at every fixed crank angle.

Referring to FIG. 11, first, in step 40, it is determined whether the engine operating state is within region I of FIG. When it is determined that the engine operating state is within region I, step 4
1, the intake control valve closing timing θ2 is determined from map 1.

The relationship between the accelerator opening degree θA and the engine speed Ne in map 1 and the intake control valve closing timing θ2 is as shown by the solid line in FIGS. 12 and 13. In FIGS. 12 and 13, the dashed line indicates the intake control valve closing timing when the throttle valve is fully open for comparison, and the intake control valve closing timing is retarded compared to when the throttle valve is fully open. I know that there is.

Referring to FIG. 12, θ2 is increased as θA increases. This is to increase the amount of intake air as the load increases.

Referring to FIG. 13, θ2 is increased as Ne increases. This is to ensure a predetermined intake valve opening time even if Ne increases.

Referring again to FIG. 11, θT is determined from map 2 in step 42. The relationship between the accelerator opening θA and the engine speed Ne in map 2 and the throttle valve opening θT is as shown in FIGS. 14 and 15.

Referring to FIG. 14, as θA increases, θT also increases. FIG. 15 shows a case where the load is constant. θT also increases as Ne increases. This is Ne
This is because combustion becomes more stable as the amount increases, so increasing the throttle valve opening can reduce pump loss.

θ2 obtained from map 1 and θT obtained from map 2 correspond to the fuel efficiency minimum point shown in FIG. In FIG. 11, if it is determined in step 40 that it is region II, the process proceeds to step 43 and θ2 is determined from map 3.

The relationship between the accelerator opening degree θA and the engine speed Ne in map 3 and the intake control valve closing timing θ2 is as shown in FIGS. 16 and 17. Referring to FIG. 16, θ2 increases as θA increases, and becomes constant at the intake valve closing timing θIC. Referring to FIG. 17, θ
2 increases as Ne increases, and the intake valve closing timing θ
It becomes constant at IC.

At step 44 in FIG. 11, θT is fully opened. Based on θ2 and θT determined based on this routine, the intake control valve and the throttle valve are controlled by another routine (not shown).

[0043]

Effects of the Invention: Combustion can be improved by reducing the drop in air-fuel mixture temperature just before ignition, and fuel efficiency can be sufficiently improved by reducing pump loss. Furthermore, since the opening degree of the throttle valve is reduced in accordance with the amount of retardation of the intake control valve closing timing, the engine output does not increase due to the retardation of the intake control valve closing timing.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an internal combustion engine equipped with an intake system of the present invention.

FIG. 2 is a plan cross-sectional view of FIG. 1;

FIG. 3 is a perspective view of the intake control valve.

FIG. 4 is a diagram showing the open and closed positions of the valve body of the intake control valve.

FIG. 5 is a diagram showing the actuator when the intake control valve is opened.

FIG. 6 is a diagram showing the actuator when the intake control valve is closed.

FIG. 7 is a diagram showing control of the intake control valve.

FIG. 8 is a diagram showing a combustion deterioration region (region I).

[Fig. 9] Intake control valve closing timing θ2 in region I
FIG. 2 is a diagram showing the relationship between throttle valve opening θT and fuel efficiency.

[Fig. 10] Intake control valve closing timing θ on boundary line L
2 is a diagram showing the relationship between throttle valve opening θT and fuel efficiency.

FIG. 11 is a flowchart for calculating θ2 and θT.

FIG. 12 is a diagram showing the relationship between θA and θ2 in map 1.

FIG. 13 is a diagram showing the relationship between Ne and θ2 in Map 1.

FIG. 14 is a diagram showing the relationship between θA and θT in map 2.

FIG. 15 is a diagram showing the relationship between Ne and θT in Map 2.

16 is a diagram showing the relationship between θA and θ2 in map 3. FIG.

FIG. 17 is a diagram showing the relationship between Ne and θ2 in Map 3.

[Explanation of symbols]

3...Cylinder chamber 6...Intake valve 11...Intake control valve 13...Throttle valve

Claims (1)

[Claims] Claim 1: An intake control valve capable of opening and closing the intake passage is provided in the intake passage between a throttle valve and an intake valve, and the intake control valve is operated at a predetermined time during a period in which the intake valve is open. In an internal combustion engine, the amount of air taken into the cylinder is controlled by opening the intake control valve for a period of time and controlling the closing timing of the intake control valve.
The closing timing of the intake control valve is retarded and the intake control valve is closed in an engine operating region where the air-fuel mixture temperature immediately before ignition decreases and combustion deteriorates because the intake control valve is closed early. An intake system for an internal combustion engine, comprising a control means for controlling an opening degree of the throttle valve to be reduced in accordance with a valve timing retard amount.