JPH0693868A - Intake system for engine - Google Patents

Abstract

PURPOSE:To improve the combustion efficiency by producing powerful tumble in an engine combustion chamber. CONSTITUTION:Two suction ports 5 are communicated with a combustion chamber 4. An auxiliary suction port 14 is opposed to a place between suction valves 7 for two suction ports 5 and open to the tangent line of tumble FA which is produced in the combustion chamber 4. A compressor 15 is connected to the auxiliary suction port 14. With the lowering of a piston 3, mixture flows through the suction port 5 into the combustion chamber 4 to produce the tumble FA. A suction flow FC in the direction of cancelling a tumble flow is produced at the place between two suction valves 7. Gas G is blown from the nozzle 14a of the auxiliary suction port 14 by the compressor 15 to force the direction of the suction flow FC to the tangent line of the tumble FA, so that the collision of the suction flow FC with the tumble FA is prevented to produce the powerful tumble.

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 tumble is generated in a combustion chamber to improve combustibility.

[0002]

2. Description of the Related Art Generally, it is known that combustibility is improved by generating a swirl in an air-fuel mixture in a combustion chamber of an engine. Therefore, various techniques for generating a swirl in the combustion chamber have been conventionally proposed. For example, JP-A-57
In Japanese Patent Laid-Open No. 198315, an auxiliary intake port is opened in the intake port, and a mixture is pressurized and supplied from the auxiliary intake port to generate a horizontal swirl (swirl) in the combustion chamber. The device is described.

Further, there is an intake device in which a swirl flow is generated in the combustion chamber by the intake flow from the intake port.

An example of this type of intake device will be described below with reference to FIG. FIG. 7 shows a cylinder head portion of the engine, where 1 is a cylinder block, 2 is a cylinder head, 3 is a piston, and 4 is a combustion chamber. The cylinder head 2 is provided with an intake port 5 and an exhaust port 6 that communicate with the inside of the combustion chamber 4. As shown in FIG. 8, two intake ports 5 and two exhaust ports 6 are arranged in parallel, each intake port 5 is provided with an intake valve 7, and each exhaust port 6 is provided with an exhaust valve 8. Has been. 8 shows the intake / exhaust valve 7 for the combustion chamber 4,
8 shows an arrangement of 8. The intake port 5 is laid at an angle close to a right angle with respect to the axial direction of the cylinder and extends in a substantially straight line. In the figure, 9 and 10 are valve springs, 11 and 12 are camshafts, and 13 is a spark plug.

With this configuration, the intake flow supplied from the fuel supply device (not shown) such as the fuel injection device or the carburetor and flowing into the combustion chamber 4 through the intake port 5 is the intake valve 7 in FIG. Since the flow on the upper part A side becomes stronger than that on the lower part B side, the intake flow on the upper part A side of the intake valve 7 becomes a tangential flow of the vortex and the clockwise vertical vortex flow F in the combustion chamber 4. Generate _A (Tumble). Then, the occurrence of this tumble improves the combustibility of the air-fuel mixture, thereby improving the engine output.

[0006]

However, in the above-mentioned conventional intake device, as shown in FIG. 9, a tumble flow is generated in a portion C (see FIG. 8) sandwiched between the lower portions B of the two intake valves 5. There is a problem that a strong intake air flow F _C occurs in the opposite direction, and this intake air flow F _C collides with the vortex flow F _A to weaken the tumble.

The present invention has been made in view of the above points, and an object thereof is to provide an intake system capable of generating a strong tumble in a combustion chamber of an engine.

[0008]

In order to solve the above-mentioned problems, the present invention makes two intake ports arranged in parallel communicate with a combustion chamber, and a tumble is generated in the combustion chamber by the intake flow of the intake port. In the intake device of the engine, a sub-injection device that injects gas toward between the intake valves that open and close the two intake ports located in the combustion chamber and directs the intake flow between the intake valves in the tangential direction of the tumble. It is characterized by having an intake port.

[0009]

With this structure, a strong tumble can be generated by injecting gas from the auxiliary intake port and directing the intake flow in the direction of canceling the tumble generated between the two intake valves in the tangential direction of the tumble. it can.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. In this embodiment, the same members as those of the conventional intake device shown in FIGS. 7 and 8 are designated by the same reference numerals, and only different portions will be described in detail.

As shown in FIG. 1, the cylinder head 2 is provided with an auxiliary intake port 14 communicating with the inside of the combustion chamber 4. The nozzle 14a of the auxiliary intake port 14 is connected to the
It is opened so as to face a portion C sandwiched between two intake valves 7 (see FIG. 2), and is provided in the tangential direction of the tumble generated in the combustion chamber 4. Here, as shown in FIG. 3, the auxiliary intake port 14 may be arranged such that the angle θ with the stem portion of the intake valve 7 is 0 ° ≦ θ ≦ 90 °.

The auxiliary intake port 14 is connected to the compressor 15, and the gas G such as air or air-fuel mixture is supplied from the nozzle 14a into the combustion chamber 4 in accordance with the intake flow flowing from the intake port 5 into the combustion chamber 4. It is designed to inject properly.

The control of the injection amount of the gas G in the auxiliary intake port 14 is performed as follows. The injection amount of the gas G of the auxiliary intake port 14 with respect to the crank rotation angle of the engine is, as shown in FIG. 5, based on the flow rate of the intake flow F _{C in} the direction of canceling the tumble, and the flow rate of the intake flow F _C is small. It is set to be small near the top dead center or the bottom dead center (where the piston speed is small), and to be increased in the middle portion where the flow rate of the intake flow F _C is large (where the piston speed is large). Further, the injection amount of the gas G of the auxiliary intake port 14 with respect to the engine speed is as shown in FIG.
The intake air-fuel mixture has a small flow rate in a low rotation speed range where combustion is likely to be unstable, and the intake air-fuel mixture has a large flow speed and combustion is stable in a high rotation speed range.

The operation of this embodiment having the above-mentioned structure will be described below.

During the intake stroke, the air-fuel mixture flows into the combustion chamber 4 through the intake port 5 as the piston 3 descends. At this time, similar to the conventional example shown in FIGS. 7 and 8,
In FIG. 1, the upper part A side of the intake valve 7 is the lower part B.
Since the flow of intake air becomes stronger than that of the intake side, the intake flow on the upper part A side of the intake valve 7 becomes a flow in the tangential direction of the vortex and a clockwise vertical vortex flow F _A (tumble) is generated in the combustion chamber 4. generate.

Further, a strong intake air flow F _{C in the} direction opposite to the tumble flow is generated at a portion C (see FIG. 2) sandwiched between the two intake valves 5. Here, as shown in FIG. 4, the auxiliary intake port 14 is changed by the compressor 15 according to the flow rate of the intake flow F _C.
The gas G injected from the nozzle 14a forcibly changes the direction of the intake flow F _C to the tangential direction of the tumble. Therefore, the intake air flow F _C can be generated a strong tumble since never vortex F _A is weakened by colliding with the vortex F _A tumble.

By thus generating a strong tumble, the combustibility in the low speed region is improved, and the engine output and the fuel consumption can be improved.

[0018]

According to the engine intake system of the present invention,
As described in detail above, a strong tumble can be generated by injecting gas from the auxiliary intake port and directing the intake flow in the direction of canceling the tumble generated between the two intake valves in the tangential direction of the tumble. . As a result, by generating a strong tumble in the combustion chamber, the combustibility in the low speed region is improved, and the excellent effect that the engine output and the fuel consumption can be improved is exhibited.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a cylinder head portion of an engine to which an embodiment of the present invention is applied.

FIG. 2 is a plan view showing the arrangement of intake and exhaust valves and auxiliary intake ports of the device of FIG.

3 is an explanatory view showing an angle between an intake valve and an auxiliary intake port of the device of FIG. 1. FIG.

FIG. 4 is an explanatory diagram showing an intake flow and a tumble generation state of the apparatus of FIG.

5 is a diagram showing the relationship between the crank rotation angle and the injection amount of gas in the auxiliary intake port of the device in FIG.

6 is a diagram showing the relationship between the engine speed and the injection amount of gas in the auxiliary intake port of the device in FIG.

FIG. 7 is a vertical sectional view of a cylinder head portion of an engine to which a conventional intake device is applied.

FIG. 8 is a plan view showing the arrangement of intake and exhaust valves and auxiliary intake ports of the device shown in FIG.

9 is an explanatory diagram showing an intake air flow and a tumble generation state of the device of FIG. 7. FIG.

[Explanation of symbols]

4 Combustion chamber 5 Intake port 7 Intake valve 14 Sub-intake port F _A Vortex (tumble) G Gas

Claims (1)

[Claims] 1. An intake system for an engine, wherein two intake ports arranged in parallel are communicated with a combustion chamber, and a tumble is generated in the combustion chamber by an intake flow of the intake port. An intake device for an engine, comprising: an auxiliary intake port that injects gas between intake valves that open and close ports, and that directs an intake flow between the intake valves in a tangential direction of the tumble.