JPH06299917A - Air intake device for multicylinder gasoline engine - Google Patents

Abstract

PURPOSE:To balance air-fuel ratio in mixture in each stream so as to improve combustibility irrespective of fluctuation of load of an engine. CONSTITUTION:A plural number of air intake port inlets are provided along the longitudinal direction in front and rear of one side wall of a cylinder head 1, these air intake port inlets communicate with a mixture distribution passage 4, and the mixture distribution passage 4 communicates with a carburetor 5 to constitute an air intake device of a multicylinder gasoline engine. Venturi sections 10a, 10b, 10c are provided at each air intake port inlet, and air intake introduction holes 11a, 11b, 11c in which A flow rate can be set are formed and opened in each venturi section 10a, 10b, 10c, respectively. These air intake introduction holes 11a, 11b, 11c communicate with an air intake passage 7 in the upstream of the carburetor 5, and the flow rate of air which flows into each air intake introduction hole 11a, 11b, 11c is controlled by a flow rate control valve 13 which is provided in the downstream of the carburetor 5 and operates by air pressure P.

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 a multi-cylinder gasoline engine, and more particularly to a technique for making the air-fuel ratio of a distributed air-fuel mixture supplied to each cylinder uniform.

[0002]

2. Description of the Related Art As an intake system for a multi-cylinder gasoline engine, there is a conventional one shown in FIG. 3, for example. In this intake device, a plurality of intake port inlets 3a, 3b, 3c are provided side by side along the longitudinal direction of one side surface of the cylinder head 1.
A gas mixture distribution passage 4 is communicated with the intake port inlets 3a, 3b, 3c, and a carburetor 5 is communicated with the gas mixture distribution passage 4. The air-fuel mixture inlet 6 of the air-fuel mixture distribution passage 4 is directed toward the center of the intake port inlet 3b. According to this intake device, the air-fuel mixture 7 from the carburetor 5 is diverted in the air-fuel mixture distribution passage 4 and the diverted air-fuel mixture 9a.
9b and 9c are supplied to each cylinder via the intake ports 8a, 8b and 8c.

[0003]

The above prior art has the following problems. Air-fuel mixture inlet 6 of the air-fuel mixture distribution passage 4
Is directed toward the vicinity of the center intake port inlet 3b, but the fuel oil droplets scattered from the mixture introduction port 6 fly far due to its inertial force, and jump into the farther intake port inlet 3c, while The amount of jump into the near intake port inlet 3a is small. Therefore, each intake port inlet 3a / 3
Each split air-fuel mixture 9a supplied to each cylinder via b3c
-The air-fuel ratios in 9b and 9c will be different, resulting in imbalance.

That is, as shown by the broken line in FIG. 2A, the air-fuel ratio in the shunt mixture 9c is too small (the fuel ratio is too large) in the intake port 8c where many fuel oil droplets have jumped in.
And the intake port 8a with less fuel oil drop in
In the inside, the air-fuel ratio in the split air-fuel mixture 9a becomes excessively large (fuel ratio is too small). This phenomenon, the lighter the engine,
Since the fuel oil droplets are large, they appear strongly during light load operation.

That is, the split air-fuel mixture 9c having an excessive fuel ratio
Exhaust gas containing a large amount of unburned harmful components is discharged from the cylinder to which is supplied, polluting the surrounding environment. In addition, combustion becomes insufficient in the cylinder to which the split air-fuel mixture 9a having an excessively low fuel ratio is supplied, and the output of the engine decreases. The present invention has been made in view of the above circumstances, and balances the air-fuel ratio in each shunt mixture regardless of the change in engine load.
Moreover, it is an object of the present invention to provide an intake system for a multi-cylinder gasoline engine that can improve combustibility.

[0006]

In order to solve the above-mentioned problems, the means adopted by the present invention is a plurality of intake port inlets 3a along the longitudinal direction of one side wall of the cylinder head 1.
3b and 3c are installed side by side, and these intake port inlets 3a and 3b
In the intake system for a multi-cylinder gasoline engine, which is constituted by communicating the mixture distribution passage 4 with 3c and the carburetor 5 communicating with the mixture distribution passage 4, the intake port inlets 3a
Vetchuri parts 10a, 10b, and 10 on 3b and 3c, respectively
Intake inlets 11a, 11b, 11c, each of which has a flow rate settable in each of the Vetchuri parts 10a, 10b, 10c.
And the intake air intake holes 11a
11b and 11c communicate with the upstream intake passage 7 of the carburetor 5, and the intake flow rate flowing into each of the intake introduction holes 11a, 11b, and 11c operates at the intake pressure P on the downstream side of the carburetor 5. The gist is characterized in that the flow rate is controlled by the flow rate control valve 11.

[0007]

[Operation] In the present invention, each intake port inlet 3a, 3b, 3
Each of the vetchuri parts 10a, 10b, and 10c is attached to the corresponding c, and the intake holes 11a, 11b, and 11c that can set the flow rate are formed in each of the vetchuri parts 10a, 10b, and 10c. Then, these intake air introduction holes 11a
The flow rates of 11b and 11c are preset. That is, the intake air inflow amount is set to a large amount at the portion where the fuel oil droplets scattered from the air-fuel mixture introducing port 6 are large, and the intake air inflow amount is set to a small amount at the portion where the scattered fuel oil droplets are small. As a result, as shown by the solid line in FIG. 2 (A), the air-fuel ratio in the air-fuel mixture flowing through the respective Vetchuri parts 10a, 10b, 10c is balanced.

Further, each of the intake introduction holes 11a, 11b, 1
Since the flow rate of the intake air flowing into 1c is controlled by the flow rate control valve 11 operating at the intake pressure P on the downstream side of the carburetor 5, as shown by the solid line in FIG. It is properly controlled according to the load (0/4 to 4/4).
Further, the air / fuel mixture is accelerated by each of the Vetchuri parts 10a, 10b, 10c, and the atomization of the fuel is promoted.

[0009]

Since the present invention is constructed and operates as described above, it has the following effects. In the present invention, regardless of changes in engine load,
The air-fuel ratio in each split air-fuel mixture can be balanced. Since the air-fuel mixture is accelerated by each of the Vetchuri parts 10a, 10b, 10c and atomization of the fuel is promoted, the combustibility can be improved.

[0010]

Embodiments of the present invention will now be described in more detail with reference to the drawings. FIG. 1 is a perspective view of an intake system for a multi-cylinder gasoline engine according to an embodiment of the present invention. The basic structure of the intake device of the present invention is configured similarly to the conventional example.
That is, as shown in FIG. 3, a plurality of intake port inlets 3a, 3b.
3c is installed side by side, and these intake port inlets 3a, 3b, 3c
The air-fuel mixture distribution passage 4 is communicated with, and the vaporizer 5 is communicated with the air-fuel mixture distribution passage 4. In FIG. 1, reference numeral E is a multi-cylinder gasoline engine, 2 is an exhaust pipe communicating with each exhaust port (not shown), and the cylinder head 1 is assembled on a cylinder block (not shown).

The characteristic structure of the present invention will be described below. In the present invention, the intake port inlets 3a, 3b, 3c are provided.
Vetchuri parts 10a, 10b, and 10c are attached to each of them. Each of these vetchuri parts 10a, 10b, 10c
Is integrally formed with the Vetchuri block 10 fixed to one side wall of the cylinder head 1.

Each of the above-mentioned vetchuri parts 10a, 10b, 10c
As shown by the main part A in FIG. 1, the flow rate setting tool 12 has intake introduction holes 11a, 11b, 11c formed therein.
Is screwed and fixed. These flow rate setting tools 12
Are exchangeably provided, and the intake introduction holes 11a
The hole diameters of 11b and 11c can be changed appropriately. That is, the flow rates of the intake air introduction holes 11a, 11b, and 11c are set in advance, and at the place where many fuel oil droplets scattered from the air-fuel mixture introduction port 6 fly in, the intake air inflow amount is set to a large amount so that the scattered fuel oil droplets At places where you jump in less, set a smaller amount of intake air inflow. As a result, as shown by the solid line in FIG. 2 (A), each of the vetchuri parts 10a, 10b, 10c.
The air-fuel ratio in the air-fuel mixture flowing through the engine is balanced.

Each of the intake air intake holes 11a, 11b, 11c
Is communicated with the upstream intake passage 7 of the carburetor 5 on the downstream side of the air cleaner 15 via the flow control valve 13. The flow rate control valve 13 is provided for each intake introduction hole 11a.
It controls the flow rate of intake air flowing into b · 11c,
It is configured to operate at the intake pressure P on the downstream side of the carburetor 5. That is, the air supply amount is properly controlled according to the engine load (0/4 to 4/4) as shown by the solid line in FIG. 2 (B). As a result, the air-fuel ratio in each of the split air-fuel mixtures can be made uniform irrespective of changes in the engine load. Also, each of the vetchuri parts 10a, 10b, 10
The air-fuel mixture is accelerated by c, and atomization of the fuel is promoted.
Thereby, the combustibility can be improved.

In the above embodiment, each vetchuri portion 10a.
Although it has been described that the 10b and 10c are integrally formed with the Vetchuri block 10, the present invention is not limited to this, and the Vetchuri block 10 and the flow rate setting tool 12 may be modified appropriately. Does not need a lot of words.

[Brief description of drawings]

FIG. 1 is a perspective view of an intake system for a multi-cylinder gasoline engine according to an embodiment of the present invention.

FIG. 2 is a graph for explaining the operation of the present invention, where FIG. 2A shows the air-fuel ratio of the air-fuel mixture sucked from each intake port inlet, and FIG. 2B is supplied from each Vetchuri portion. Indicates the air supply amount.

FIG. 3 is a cross-sectional plan view of an intake system for a multi-cylinder gasoline engine according to a conventional example.

[Explanation of symbols]

1 ... Cylinder head, 3a / 3b / 3
c ... intake port inlet, 4 ... mixed mood flow passage,
5 ... Vaporizer, 7 ... Vaporizer 5 upstream intake passage,
10a, 10b, 10c ... Vetchuri section, 11a, 11
b · 11c ... Intake inlet hole, 13 ... Flow control valve, P ... Intake pressure on the downstream side of the carburetor.

Claims (1)

[Claims] 1. A plurality of intake port inlets (3a), (3b), (3) along a longitudinal direction of one side wall of a cylinder head (1).
c) is installed side by side, and these intake port inlets (3a), (3b),
In the intake system for a multi-cylinder gasoline engine, which is constituted by connecting the mixture distribution passage (4) to (3c) and the carburetor (5) to the mixture distribution passage (4), the intake port inlets ( 3a), (3b), and (3c) are provided with vetchuri parts (10a), (10b), and (10c), respectively, and the intake air of which the flow rate can be set for each vetchuri part (10a), (10b), and (10c) The introduction holes (11a), (11b), (11c) are formed by opening, and the intake introduction holes (11a),
(11b) and (11c) communicate with the upstream intake passage (7) of the carburetor (5), and the intake flow rate flowing into each of the intake introduction holes (11a), (11b) and (11c) is An intake system for a multi-cylinder gasoline engine, characterized in that the flow rate is controlled by a flow rate control valve (13) operating at an intake pressure (P) on the downstream side of the carburetor (5).