JP2002221036A - Intake system for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of parts by making a throttle valve function as an intake control valve and to improve response to load variation under a low load operation condition including idling. SOLUTION: A throttle body 8 is mounted between a cylinder head 3 and an intake manifold 9. A main intake passage 13 and a sub intake passage 14 generating tumble flow are formed in the throttle body 8. In a low load operation condition in which a throttle valve 16 is fully closed, quantity of intake air supplied to a combustion chamber 5 is controlled by an ISC valve 18 mounted in an idle passage 17 to improve response to load variation. In a medium load operation area, the main intake passage 13 is maintained in a closed valve condition by a concave surface part 8b formed in the main intake passage 13 and just the sub intake passage is opened. In a heavy load operation condition, both intake passages 13, 14 are opened.

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 engine in which a throttle valve also functions as an intake control valve.

[0002]

2. Description of the Related Art Conventionally, in a low / medium load operation region including idling with a small intake air amount, a vortex such as a tumble flow and a swirl flow is generated in a combustion chamber to enhance the gas flow in the combustion chamber and improve the combustion efficiency. Techniques for improving are known.

In general, this type of intake passage branches downstream from a throttle valve into a large-diameter main intake passage and a small-diameter low-load intake passage, and is provided with an intake control valve in the main intake passage. ,
During low / medium load operation, the intake control valve closes the main intake passage and supplies intake air from the auxiliary intake passage side to the combustion chamber to generate turbulence such as tumble and swirl in the combustion chamber. I have.

However, in such a conventional intake device,
Since the intake control valve must be provided separately from the throttle valve, and a mechanism for opening and closing the intake control valve is also required, there is a problem that the number of parts is large and the structure is complicated.

[0005] For this reason, the present applicant has disclosed in Japanese Patent Application Laid-open No. Hei 8-312.
No. 358, a throttle valve is arranged near an intake port, and during low / medium load operation with a small throttle opening, the main intake passage is closed by the throttle valve and the sub intake passage is opened. At the time of large high-load operation, a technique was proposed in which both intake passages were opened to allow the throttle valve to also function as an intake control valve.

[0006]

However, according to the technology described in the above publication, the amount of intake air at the time of idling is controlled by the opening of the throttle valve. However, there is a problem that the followability to the load during the idling operation is poor, and the engine speed is likely to be unstable.

In view of the above circumstances, the present invention reduces the number of parts by using the function of an intake control valve as a throttle valve, and has the ability to follow load fluctuations during low load operation including idle operation. An object of the present invention is to provide an intake device for an engine capable of obtaining a good and stable idle rotation.

[0008]

In order to achieve the above object, an intake device for an engine according to the present invention is provided with a throttle bore near an intake port, and a throttle valve capable of fully closing the throttle bore is provided in the throttle bore. A main intake passage and a sub-intake passage for generating a vortex in the combustion chamber are disposed via a partition wall downstream of the throttle valve in the throttle bore, and a sub-intake passage is provided downstream of an idle passage bypassing the throttle valve. And an idle speed control valve is interposed in the idle passage.

In such a configuration, during idling operation with the accelerator pedal released, the throttle valve fully closes the throttle bore, and the intake air is discharged to the auxiliary intake passage through the idle passage bypassing the throttle valve. A vortex is generated in the combustion chamber by the airflow flowing from the auxiliary intake passage to the combustion chamber. When the throttle valve is gradually opened, the sub air passage opens first, and then the main intake passage opens. In the low / medium load operation area where the sub air passage opens,
A vortex is generated in the combustion chamber by the airflow flowing through the sub air passage. Also, in a high load region where both the sub air passage and the main intake passage are opened, a large amount of intake air is supplied to the combustion chamber via both air passages.

In this case, preferably, the main intake passage is provided with a concave curved surface portion for maintaining the closed state of the main intake passage in a range of a set opening angle from a fully closed state of the throttle valve. .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 5 show a first embodiment of the present invention. Here, FIG. 1 is a schematic diagram of an intake device of an engine.

Reference numeral 1 in the figure denotes an engine body, and in the figure, a four-cylinder engine is shown. As shown in FIGS.
In each cylinder, a combustion chamber 5 is formed by the cylinder block 2, the cylinder head 3, and the piston 4 of the engine body 1.

The cylinder head 3 is formed with an intake port 6 and an exhaust port 7 communicating with each combustion chamber 5.
The intake ports 6 are of a two-port type branched into two branches via a partition, and each intake port 6 is provided with an intake valve 6a. Although not shown, the exhaust port 7 is provided with an exhaust valve.

A throttle body 8 is fixedly provided at an upstream opening end of an intake port 6 opening to the cylinder head 3, and a downstream end of an intake manifold 9 is connected to the throttle body 8, and an upstream of the intake manifold 9 is provided. It is assembled in an air chamber 10, and the upstream of the air chamber 10 is connected to an air cleaner (not shown) via an intake passage 11.

In a throttle bore 8a formed in the throttle body 8, a main intake passage 13 having a large cross-sectional area is formed on the lower side of FIG. An injector 15 faces the auxiliary intake passage 14. Partition wall 1
The upstream side of 2 is slightly bent to face almost the center of the throttle bore 8a, and a throttle valve 16 is supported at an end thereof.

As shown in FIG. 1, the throttle valves 16 provided for each cylinder are connected to each other and operate integrally. The throttle valve 16 is mechanically connected to an accelerator pedal (not shown). When the accelerator pedal is released, the throttle valve 16 uniformly closes the throttle bore 8a as shown in FIG. And still,
The throttle valves 16 may be electronically controlled throttles. In this case, the opening of each throttle valve 16 may be individually controlled by a throttle actuator.

The upstream side of the throttle valve 16 and the auxiliary intake passage 14 are communicated via an idle passage 17, and an idle speed control (ISC) valve 18 is interposed in the idle passage 17. The ISC valve 18 is connected to an actuator that operates in response to a control signal from an electronic control unit (not shown). By electronically controlling the valve opening, the ISC valve 18 is independent of the throttle valve 16 and is independent of the combustion chamber. The idle air control unit 5 adjusts the amount of air supplied to the air conditioner 5, and performs idle-up control during warm-up operation and when driving auxiliary devices such as an air conditioner, and rotation speed control during idle operation.

The throttle valve 16 is set so as to be rotatable counterclockwise in conjunction with an accelerator pedal (not shown) from the fully closed state shown in FIG. The upper half of 16 adjusts the amount of air passing through the sub intake passage 14, and the lower half adjusts the amount of air passing through the main intake passage 13.

As shown in FIG. 5, a throttle bore 8a through which the tip of the throttle valve 16 of the main intake passage 13 passes.
In the figure, a concave curved surface portion 8b having a shape along the locus of the outer periphery of the throttle valve 16 is formed in a range of a predetermined opening degree θth from the fully closed state to the medium load operation region of the throttle valve 16.

Therefore, the main intake passage 13 is kept fully closed until the tip of the throttle valve 16 passes through the concave curved surface portion 8b, that is, until the opening angle of the throttle valve 16 becomes equal to or larger than the opening degree θth. The intake air flowing through the auxiliary intake passage 14 flows into the combustion chamber 5 along the inner wall of the intake port 5,
A tumble flow is generated in the combustion chamber 5.

Next, the operation of the intake device having such a configuration will be described. In a low-load operation region including an idling operation in which an accelerator pedal (not shown) is released, as shown in FIG.
Is blocked, and the intake air is supplied to the auxiliary intake passage 14 via the idle passage 17 bypassing the throttle valve 16.

At this time, the amount of air supplied to the combustion chamber 5 is I
Controlled by the SC valve 18. An electronic control unit (not shown) sets a target idle speed during normal operation, and sets a target engine speed during warm-up operation based on, for example, a coolant temperature detected by a water temperature sensor. Is set, a target idle-up rotation speed is set. Then, the ISC is set so that the actual engine speed converges to the set target engine speed.
The valve opening of the valve 18 is feedback-controlled.

The intake air flowing through the sub-intake passage passes through the sub-intake passage 14 at a high flow rate, and flows in one direction toward one of the combustion chambers 5 along the intake port 5 as shown by an arrow in FIG.
In the present embodiment, a tumble flow turning in the cylinder axial direction is generated in the combustion chamber 5. At this time, fuel is injected from the injector 15 at a relatively late timing, mixing of the fuel injected from the injector 15 with the intake air is promoted, and good combustion can be obtained.

When an accelerator pedal (not shown) is depressed, the throttle valve 16 rotates counterclockwise in FIG. Then, as shown in FIG. 3, the upper half of the throttle valve 16 gradually opens the auxiliary intake passage 14. On the other hand, the lower half of the throttle valve 16 is closed to the extent of the opening degree θth (see FIG. 5) passing through the concave curved surface portion 8b formed in the throttle bore 8a of the main intake passage 13, so that the sub intake air is closed. At a high flow rate through passage 14,
More intake air than in the low-load operation region flows in a direction deviated to one side of the combustion chamber 5, and generates a tumble flow swirling in the cylinder axial direction in the combustion chamber 5.

As a result, during the period from the idling operation in which the throttle valve 16 is fully closed to the medium load operation region, the gas flow is strengthened by the tumble flow generated in the combustion chamber 5, and good combustion is obtained.

Then, when the accelerator pedal is further depressed and the opening of the throttle valve 16 reaches a high-load operation region equal to or larger than θth, as shown in FIG. 4, both the sub intake passage 14 and the main intake passage 13 are opened. Since the valve is opened and the intake resistance decreases accordingly, a large amount of intake air is supplied to the combustion chamber 5, and a high charging efficiency for the combustion chamber 5 is obtained. At this time, fuel is injected from the injector 15 at a relatively early timing, and the fuel and the intake air are supplied to the combustion chamber 5 in a state of being sufficiently premixed, so that the fuel is satisfactorily burned and the engine output increases.

Further, since the throttle valve 16 is disposed at a position close to the intake port 5, the throttle response is good and the acceleration performance according to the driver's intention can be obtained.

As described above, in the present embodiment, the throttle valve 16 is arranged at a position close to the intake port 5, and the throttle valve 16 is made to also have the function of the conventional intake control valve. The number of points is reduced, and the structure can be simplified.

In the low load operation region where the throttle valve 16 is fully closed, intake air is supplied to the auxiliary intake passage 14 through the idle passage 17 provided with the ISC valve 18.
Good followability to fluctuations in engine load and stable idling can be obtained.

Further, since the throttle valve 16 is disposed at a position close to the intake port 5, the throttle response is improved.

FIG. 6 is a schematic diagram showing an intake system for an engine according to a second embodiment of the present invention. In the first embodiment, the idle passages 17 are provided for each cylinder, and the ISC valves 18 are provided in the respective idle passages 17. However, in the present embodiment, the upstream of each of the idle passages 17 is provided via the collecting portion 17a. At the same time, the upstream end of the collecting portion 17a is connected to the intake passage 11 communicating upstream of the air chamber 10, and an ISC valve 18 is interposed in the collecting portion 17a.

According to the present embodiment, the engine speed during idle operation is controlled by one ISC valve 18 interposed in the collecting portion 17a, so that the control becomes easy and the number of parts is reduced. By the reduction, the cost of parts and the cost of manufacturing can be reduced.

According to the present embodiment, as shown in FIG. 6, a left main intake passage 13 and a sub intake passage 14 are formed in the throttle body 8 with a partition 12 interposed therebetween. Since each idle passage 17 communicates with the sub intake passage 14, the intake air flowing through the sub intake passage 14 is connected to one intake passage until the throttle valve 6 is fully closed or the throttle valve 6 becomes a predetermined angle θth or more. The swirl flow can be generated only in the port and swirl in the combustion chamber 5 in a direction perpendicular to the cylinder axis.

[0034]

As described above, according to the present invention,
The throttle valve also functions as an intake control valve, so the number of parts can be reduced.In addition, the throttle valve is located close to the intake port, improving throttle response and improving the driver's intention. Acceleration performance along the range can be obtained.

Further, since the downstream of the idle passage bypassing the throttle valve is opened to the auxiliary intake passage and an idle speed control valve is interposed in the idle passage, low load including idle operation when the throttle valve is fully closed is provided. Good followability to load fluctuations during operation is obtained, and stable idle rotation can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an intake device for an engine according to a first embodiment;

FIG. 2 is a longitudinal sectional view of a main part of the intake device during low load operation.

FIG. 3 is a longitudinal sectional view of a main part of the intake device during a middle load operation.

FIG. 4 is a longitudinal sectional view of the intake device during a high-load operation.

FIG. 5A is a cross-sectional plan view of the throttle body,
(B) BB cross-sectional view of (a), CC cross-sectional view of (C) and (a)

FIG. 6 is a schematic diagram of an intake device for an engine according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine main body 5 Combustion chamber 6 Intake port 8a Throttle bore 8b Concave curved surface part 13 Main intake passage 14 Sub intake passage 16 Throttle valve 17 Idle passage 18 Idle speed control valve

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F02D 9/10 F02D 9/10 H F02M 69/32 33/00 318J

Claims (2)

[Claims] A throttle bore provided in the vicinity of an intake port, a throttle valve capable of fully closing the throttle bore is provided in the throttle bore, and a vortex flows into a main intake passage and a combustion chamber downstream of the throttle valve. And a sub-intake passage that generates the air flow is disposed via a partition, and a downstream of the idle passage that bypasses the throttle valve is opened to the sub-intake passage, and an idle speed control valve is interposed in the idle passage. An intake device for an engine, characterized by: 2. The main intake passage is provided with a concave surface portion for maintaining the closed state of the main intake passage in a range of a set opening angle from a fully closed state of the throttle valve.
An intake device for an engine as described.