JPH0131017B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of an intake system for a dual intake internal combustion engine, and in particular, the secondary side throttle valve abutting part of the secondary intake passage for high loads is formed to have a small diameter, and the The present invention relates to an intake system for a dual intake internal combustion engine which prevents next valve leakage, facilitates machining, reduces machining costs, and maintains good charging efficiency in a high load range.

There is a dual-intake internal combustion engine that has a primary intake passage for bottom loads and a secondary intake passage for high loads, and has a secondary throttle valve for each cylinder.

In this engine, a secondary throttle valve is provided for each cylinder, so if intake air leakage occurs at this secondary throttle valve, so-called secondary valve leak, the intake flow rate from the primary intake passage will decrease. As a result, it becomes impossible to improve combustibility, which is the aim of dual-intake engines. In addition, the idling speed is high and unstable, which increases harmful components in the exhaust gas and worsens fuel efficiency.

In order to prevent this secondary valve leak, conventionally, the inner wall of the passage in the throttle body, which is the contact part of the secondary intake passage with the secondary throttle valve, was machined over a wide area with high precision, and the secondary throttle valve was machined with high precision. Accuracy also needs to be improved, which increases the number of processing steps and causes an increase in costs.

Furthermore, since there is a significant difference in passage cross-sectional area between the primary intake passage for bottom loads and the secondary intake passage for high loads,
There was also the problem that the output increased rapidly during so-called connection, resulting in a lack of smooth drivability.

SUMMARY OF THE INVENTION An object of the present invention was to solve the problems of the conventional art, and to improve the secondary intake passage for high loads, which has a secondary throttle valve for each cylinder.
By forming the next throttle valve contact part to have a small diameter,
The purpose is to solve the above problems.

Embodiments of the present invention will be described below based on the drawings. In the figure, 2 is a combustion chamber, 4 is a cylinder,
6 is a piston, 8 is a spark plug, 10 is an intake valve, 12
is the cylinder head, 14 is the throttle body, 1
6 is an intake manifold, 18 is a primary intake passage for bottom load, 20 is a secondary intake passage for high load, and 22 is a secondary throttle valve. The throttle body 14
The contact portion 24 of the secondary throttle valve 22 is formed to have a diameter D1 approximately equal to the diameter of the conventional secondary intake passage.
An upstream stage 26 is formed on the upstream side of 4, and a downstream stage 28 is formed on the downstream side. An intake manifold 16 is connected to the upstream stage 26, and a secondary intake passage of the intake manifold 16 is formed to have a large diameter D2.
Similarly, the secondary intake passage 20 of the cylinder head 12 communicating with the downstream stage 28 side has a large diameter D.
Form into 2. That is, only the contact portion 24 of the secondary throttle valve 22, which is the range from X1 to X2, is formed to have a small diameter.

Next, the effect will be explained.

Since the contact portion 24 of the secondary throttle valve 22 of the throttle body 14, that is, the portion sandwiched by X1 and X2, is formed to have a small diameter, the contact portion 24 on the inner surface of the passage
The precision finishing of No. 4 is good only within this range, and the machining area is reduced. Therefore, there are advantages in that processing costs are reduced, manufacturing is easy, and processing accuracy is further improved. In addition, by forming the contact portion 4 with a small diameter, the contact surface area of the valve is reduced and secondary valve leakage can be reduced.
It is possible to maintain low idling speed and stable rotation, which helps purify exhaust gas and improves fuel efficiency. Further, by forming the contact portion 24 to have a small diameter, it is possible to promote atomization of fuel in a high load region. Further, since the ventilation passages in the upstream and downstream portions of the contact portion 24 connected to the stages 26 and 28 are formed to have a large diameter D2, the filling efficiency can be maintained at a good level.

Further, by providing the upstream stage 26, the intake air is prevented from flowing along the wall surface of the intake manifold 16 at the initial stage of opening of the secondary throttle valve 22, that is, at the beginning of opening as shown by the imaginary line in FIG. First, it collides with this upstream stage 26, and then this abutting portion 2 of the throttle body 14 configured to have a small diameter collides with the upstream stage 26.
4, there is no inconvenience that a large amount of intake air passes through the secondary throttle valve 22 in the middle load range when the secondary throttle valve 22 is initially opened. For this reason, as in the past,
It is possible to prevent a sudden increase in output that occurs simultaneously with the opening of the secondary throttle valve 22, and to ensure smooth operability. In other words, the opening characteristics (permeation cross-sectional area) of the secondary throttle valve are extremely ideal due to the upstream stage 26, and smooth operability is obtained.

Furthermore, due to the presence of the upstream stage 26 and the downstream stage 28, the direction of the intake air flowing close to the passage wall is changed and small turbulence is generated, so that the effect of fuel atomization is also secondary. can be obtained.

As is clear from the above description, according to the present invention, secondary valve leakage can be prevented, idling can be maintained at low speed and stable rotation, and this is useful for cleaning exhaust gas and improving fuel efficiency. be able to. Furthermore, since the passages other than the contact portion can be configured to have a large diameter, the filling efficiency can also be improved. In addition, since the abutment part is formed with a small diameter and an upstream stage and a downstream stage are provided, it is possible to promote atomization of the fuel, and it is possible to maintain the fuel on the lean side as a whole and obtain maximum output. Combined with the improvement in combustibility due to intake swirl, fuel efficiency can be improved. Moreover, this paragraph makes the opening characteristic of the secondary side throttle valve ideally gentle, and smooth drivability can be obtained. Also 2
Since the next side valve abutment part has a narrow area, precision machining becomes easy and the machining cost can be kept low.

Note that this invention is not limited to the above embodiments,
Various modifications are possible. For example, in the above embodiment, while the secondary side throttle valve abutting portion is formed to have the same minimum passage cross-sectional area as the conventional secondary intake passage diameter, other parts of the high-load secondary intake passage are The diameter of the secondary intake passage is larger than that of the conventional secondary intake passage. The diameter is even smaller than the path diameter to prevent secondary valve leaks and further reduce the machining area.
It can also be manufactured easily and inexpensively. In this way, the atomization of the fuel can be further promoted. Furthermore, even if the diameter of the abutting portion is even smaller than that of the conventional intake passage, the distance between X1 and X2 is extremely short, so there is no risk of significantly reducing the filling efficiency.

[Brief explanation of drawings]

The drawings show one embodiment of the invention.
The figure is a front longitudinal sectional view of the main parts of an internal combustion engine, and Figure 2 is a front longitudinal cross-sectional view of the main parts of an internal combustion engine.
FIG. 18...Primary intake passage for bottom load, 20...Secondary intake passage for high load, 4...Cylinder, 22...2
Next side throttle valve, 24...Secondary side throttle valve contact part, 26
...upstream paragraph, 28...downstream paragraph.

Claims (1)

[Scope of Claims] 1. In a dual intake internal combustion engine having a primary intake passage for bottom load and a secondary intake passage for high load, and having a secondary throttle valve for each cylinder, the secondary intake passage for high load An intake system for a dual intake internal combustion engine, characterized in that a secondary throttle valve abutting portion of an intake passage is formed to have a small diameter. 2 The secondary side throttle valve abutting part is formed to have the same minimum passage cross-sectional area as the conventional secondary intake passage, and the other parts of the high-load secondary intake passage are made larger than the conventional secondary intake passage. An intake device for a dual intake internal combustion engine according to claim 1, characterized in that the intake device is formed to have a diameter. 3. The secondary intake passage for high loads is formed to have a larger diameter than the conventional secondary intake passage, and the secondary side throttle valve abutting part of this secondary intake passage is made smaller in diameter than the conventional secondary intake passage. An intake system for a dual intake internal combustion engine according to claim 1.