JPS608457A - Intake manifold - Google Patents

Abstract

PURPOSE:To improve distribution of an EGR gas to each cylinder and aim at improvement in output, by communicating meeting portions of an intake manifold with each other through a first balance tube, communicating riser portions thereof with each other through a second balance tube, and connecting an ERG gas supply passage with the second balance tube between the riser portions. CONSTITUTION:As an EGR gas supply passage 48 is provided at a center of or near a balance tube 46, an EGR gas is inclined to flow into intake manifolds 22 and 23 to the same extent, and simultaneously an unbalance area of flow rate upon full opening of a throttle valve is narrowed, thereby improving distribution to each cylinder. Further, as pulsation of suction air has been already damped by a balance tube 57 in the position of the balance tube 46, it is possible to reduce influence of such a pulsation to distribution of the EGR gas inducted to the balance tube 46 or air for compensation of an air-fuel ratio. Accordingly, distribution of the EGR gas to each cylinder may be improved thereby to improve an engine output.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-cylinder internal combustion $1 intake manifold with variable venturi multiple carburetors.

In a variable venturi type carburetor, it is desirable to suppress pulsation in order to prevent pulsations that occur in the intake manifold in synchronization with the intake timing from being transmitted to the carburetor part and causing the variable venturi to flap.

In order to suppress pulsation, it is effective to cause the pulsations of cylinders with different phase differences to interfere with each other so that the peaks and troughs of pressure fluctuations cancel each other out. It is effective to communicate the intake passages of the cylinders with balance tubes.

This is an example of an intake manifold for a multi-cylinder internal combustion engine equipped with fixed venturi-type multiple carburetors.As shown in FIG. There are some that suppress pulsation. However, in the example of FIG. 1, since the intake manifolds 1 were communicated at the riser section 3, the intake air easily flows from one intake manifold to the other through the balance tube 2, and as shown in FIG. As shown, there was a problem in that the intake air MA and B passing through each carburetor became unbalanced, especially in the high speed range, leading to deterioration in air-fuel mixture distribution and a decrease in output.

Although this is an example connected to a side draft type carburetor, there is also one in which all branch ports 5 of the intake manifold 4 are communicated through a balance tube 6, as shown in FIG.

However, if all the branch ports 1 to 5 are communicated, as shown in FIG.
When connected, the torque and output of β decreases by about 5% compared to , and since the balance tube 6 is excreted onto the branch boat 5, the height increases, making it difficult to use in a downdraft type. There was a problem.

That is, the suppression of pulsation using the balance tube communication structure has the problems of flow imbalance and output reduction, which are difficult to achieve at the same time. In order to solve this problem, the present applicant proposed an intake manifold 7 connected to a variable venturi type carburetor, as shown in FIG. A new intake manifold 7 has been proposed in which the intake manifold 7 is communicated with a tube 10 and the riser portion 11 is also communicated with another balance tube 12. With the intake manifold 7 having such a structure, as will be described later, it is possible to effectively suppress pulsation transmitted to the variable venturi, suppress the flow imbalance between the carburetors, and prevent a decrease in output.

The present invention further develops the structure of the novel intake manifold as shown in FIG. The object of the present invention is to provide an intake manifold structure that provides good operation to the EGR system.

In the intake manifold of the present invention that achieves this object, each intake manifold connected to each carburetor of the variable venturi type multiple carburetor is communicated by a first balance tube at a portion directly below the carburetor. In addition, the EGR gas supply passage is connected to the first balance tube at a position remote from the exhaust gas generator through a second balance tube. In the EGR gas supply passage,
A feedbank passage for air for air-fuel ratio compensation may also be connected.

In such an intake manifold that is connected to an EGR system, an EGR gas supply passage is connected to the center of the first balance tube, thereby improving EGR or air distribution. Further, since the pulsation is attenuated by the second balance tube, the EGR gas introduced into the Ml balance tube is less affected by the intake pulsation.

Note that the intake manifold connected to each carburetor is connected by two balance tubes, so it has the same effect as the carburetor shown in Figure 5, that is, suppresses pulsation transmitted to the variable venturi, and suppresses each carburetor. Naturally, the effects of suppressing the flow imbalance between the devices and preventing the output from decreasing can be obtained.

Hereinafter, preferred embodiments of the intake manifold of the present invention will be described with reference to the drawings.

6 and 7 illustrate an intake manifold according to one embodiment of the present invention. The figure shows an example of the intake manifold of a four-cylinder engine equipped with a down and raft variable bench lily type twin carburetor. In the figure, reference numeral 21 indicates the entire intake manifold, and reference numerals 22 and 23 indicate the constituent parts of the intake manifold that are connected to the respective carburetors 24 and 25 of the 2M type carburetor. Intake manifold 22.23
are of the same shape, and are located directly below the downdraft variable venturi type carburetor 24.25.
The riser section 26. which changes the flow from the engine at right angles to the engine side.
27, two collecting parts 28.2 extending almost horizontally from the riser part 26.27 toward the engine side, and collecting parts 28.29.
branch ports 32, 33, 34, and 35 that extend downstream from the branch sections 30, 31 toward each cylinder independently of each other. . Branch boat 32 of intake manifold 21.
33, 34, and 35 are connected to respective intake boats 37 formed in the cylinder head 36, and connected to the #1 cylinder, #2 cylinder, #3 cylinder, and #4 cylinder, respectively, via intake valves.

Branch boat 32.33.34.3 of intake manifold 21
The branch boats 32 and 33 at the back of No.
．． 35 (The carburetor 25 is responsible for most of the intake air and fuel supply.

The branch boats 32 and 33 are separated from the branch part 30, spread apart from each other as they go downstream, and then curve toward the engine side and extend parallel to each other, communicating with the intake boat 37 of the cylinder head 36. are doing. Similarly,
The branch boats 34 and 35 are separated from the branch part 31 and spread apart from each other as they go downstream, and then curve toward the engine side and extend parallel to each other to reach the intake boat 37 of the cylinder head 36. It's communicating.

Above the riser section 26.27 is a throttle valve 38 for each of the carburetors 24.25.

The carburetors 24 and 25 are variable venturi type carburetors, and the structure itself is known, but the negative pressure generated in the three venturi parts is inside the suction piston 41 and the case 40.
The position of the suction piston 41, that is, the opening area of the three venturi parts, is determined by the balance with the suction spring 42. A needle 43 is fixed to the suction piston 41, and the amount of fuel is controlled by the diameter of the needle. Note that 44 is a vent for communicating the float chamber 45 of the variable venturi carburetor 40 with the atmosphere to keep the pressure of the float chamber 45 constant.

The intake manifolds 22.23 connected to the respective carburetors 24.25 constituting the dual carburetor are communicated by a first balance tube 46 at each riser portion 26.27.

The first balance tube 46 extends horizontally through the side wall of the riser section 26,27.

The intake manifold 22.23 is therefore the carburetor 24.2.
5, the first balance tube 46 communicates with the first balance tube 46.

In addition, each of the vaporizers 24 configuring the dual vaporizer.
The intake manifold 22.23 connected to the carburetor 2
4.25 and communicated by a second balance tube 47. In the illustrated example, the second balance tube 47 interconnects the branches 30.31 of each intake manifold 22.23. The communication part of the second balance tube 47 is not limited to the branch part 30.31, but is connected to any one of the plurality of branch boats connected to each carburetor 24.25, that is, the carburetor 24. For example, the branch boat 33 connected to the #2 cylinder and the branch boat 34.3 connected to the carburetor 25.
Any one of the branch boats, for example, the branch boat 34 connected to the #3 cylinder, may be communicated with each other through a second balance tube 47. In the illustrated example, the second balance tube 47 is provided between the side walls of the branch 30.31 and extends horizontally in a straight line.

Therefore, the intake manifold 22.23 is connected to the carburetor 24.23.
25, the first balance tube 46
The second balance tube 47 communicates with the carburetor 24, 25 at a portion directly below the carburetor 24, 25 toward the engine. The sum of the passage cross-sectional area of the first balance tube 46 and the passage cross-section area of the second balance duplex 47 should be larger in terms of suppressing pulsation and preventing fuel from blowing out, but one intake manifold 22. In order to suppress the flow rate flowing from 23 to the other intake manifold 23.22, it is better to have a smaller size, and the branch boat 32.33.34.35
The cross-sectional area of any one of the passages is set to be less than or equal to the cross-sectional area of one of the passages.

Since this required passage cross-sectional area is distributed between the first balance tube 46 and the second balance tube 47, the passage cross-sectional area of the first balance tube 46 that communicates with the riser portions 26 and 27 is shown in FIG. This is much smaller than the passage cross-sectional area of the balance tube 2, which communicates only the riser portion.

An EGR gas supply passage 48 is connected to the first balance tube 46 at or near the center in the longitudinal direction. An EGR valve 4 is installed in the EGR gas supply passage 48.
9 is provided to communicate or cut off the EGR passage 50 connected to the EGR valve 49 and the EGR gas supply passage 48. The EGR valve 49 is connected to the EGR passage 50.
It is composed of a valve 51 that opens and closes the valve, a diaphragm 52 that drives the valve 51, and the like. The other end of the EGR passage 50 is connected to the exhaust system of the engine.

An air-fuel ratio compensation air feedback passage 53 is also connected to the EGR gas supply passage 48 . The other end of the feedback passage 53 is connected to an air cleaner.

This feedback path 53 may not be provided in some cases. If the feedback passage 53 is provided, the EGR
The gas supply passage 48 also serves as an air-fuel ratio compensation air supply passage.

Next, the operation of the intake manifold of the embodiment configured as described above will be explained.

First, the intake air is venturi part 39, throttle valve 38
The flow passes through the intake manifold 22.23, and the riser section 26.27 of the intake manifold 22.23 changes the direction of the flow toward the engine, and when EGR gas and air for air-fuel ratio compensation are introduced, the riser section 26.27 is given,
The flow then passes through the collecting section 28.29 and reaches the branching section 30.31, where the flow is divided into each cylinder, and passes through the branching boat 32.33.34.35 to the #1 cylinder and #1 cylinder, respectively. It flows to cylinder 2, cylinder #3, and cylinder #4. At this time, intake pressure fluctuations, that is, pulsations with mutually different phases occur in the #1 cylinder, #2 cylinder, #3 cylinder, and #4 cylinder in accordance with the intake timing.

This pulsation is transmitted via the first balance tube 46 and the second balance tube 47 to the respective carburetor 24.2.
Pressure fluctuations having different phases can be transmitted between the intake manifolds 22 and 23 connected to the intake manifold 5, and the peaks and troughs of the pressure fluctuations overlap and cancel each other out, so that pulsation is suppressed. The record of pressure fluctuation is the first balance tube 46
and the transmission of pressure waves through the second balance tube 47, and if there is a communication path through which even pressure waves can be transmitted, the flow of actual intake air in the first and second balance tubes 46, 47. Since the transfer can be made in an instant without the need for a The inside of the intake manifold 21 can communicate with each other, and pulsation can be effectively suppressed. Therefore, the pulsation transmitted to the venturi section 39 is suppressed, and the fluttering of the suction piston 41 of the venturi section 39, which tends to occur during idling, is suppressed, and the performance of the carburetor is maintained well.

On the other hand, from the perspective of flow balance, #1 cylinder, #
Since the branch boats 32 and 33 connected to the two cylinders are substantially symmetrical to each other, the flow rates of the air-fuel mixture flowing through the branch boats 32 and 33 tend to be substantially equal. Further, for the same reason, the flow rates of the mixing diagram flowing through the branch boats 34 and 35 tend to be approximately equal. By communicating this with the first and second balance tubes 46 and 47, the branch boat 32
．． 33, 34, and 35, and therefore the flow port balance between the vaporizers 24 and 25 is disrupted.

However, regarding the second balance tube 47 that communicates with the branch portion 30.31, the throttle valve 38
The large intake flow when fully opened is at the branch part 30.31.
It has a tendency to continue flowing in the flow direction nearby, and does not try to flow into the second balance tube 47. That is, the branch part 3o of one carburetor 24 passes through the second balance duplex 47 to the other carburetor 2.
In order for the flow to flow to the branch part 31 of No. 5, the direction of the flow must be changed at the entrance to the second balance tube 47, but since the flow near the branch part 30.31 already has directionality, It is difficult to flow into the balance tube 47.

Regarding the first balance tube 46, that is, the first balance tube 46 that communicates with the riser part 26.27, the intake air that has changed its flow direction by hitting the bottom wall surface of the riser part 26.27 is Since it also flows into the balance tube 46, the first
However, since the passage cross-sectional area of the first balance tube 46 is small as shown above, the flow resistance is large, and in reality, the flow through the first balance tube 46 is large. The flow to the intake manifold on the carburetor side is small.

Comparing this with the previous example shown in Fig. 1, in the device shown in Fig. 1, the balance tube 72 is installed only in the riser section, and the balance tube 2 has a large passage cross-sectional area. The intake air that hits the riser part 3 and changes its flow in all lateral directions easily flows into the balance tube 2, and the balance tube 2 has low flow resistance.
It can easily flow into the intake manifold 1 on the side of another carburetor through the carburetor, and the balance of the flow ports between each carburetor is likely to be lost.

On the other hand, in the embodiment of the present invention in which two balance tubes are provided and the passage cross-sectional area of the first balance tube 46 that communicates with the riser portions 26 and 27 is reduced, the intake air flows from other cylinders. It is difficult for the air to flow into the intake manifold, and the balance of the flow ports between each carburetor is also difficult to lose. Therefore, imbalance in flow rates between the vaporizers is suppressed.

FIG. 8 shows the engine speed of the engine intake system with the intake manifold installed and each carburetor 24.2 in the embodiment of the present invention.
5 shows the relationship with the flow vessel. As can be seen from a comparison between the same figure and FIG. 2, in the present invention, an unbalance in the flow rate is unlikely to occur up to a high load rotation range, and even if an unbalance occurs, it is small.

When each outlet flowing through the branch boat 32, 33, 34, 35 is stably balanced, the amount of intake air into the cylinder will be increased, and therefore the engine output will also be increased. In addition, since the flow rate of intake air flowing through each carburetor 24 and 25 is stabilized, the air-fuel ratio can be maintained easily, preventing a drop in output, and preventing the mixture from becoming excessively rich or lean. This is also advantageous in terms of exhaust gas control.

In addition, the second balance tube 47 allows the branch portion 30 to
．． Even if the riser parts 26 and 27 are connected through the first balance tube 46, the decrease in output can be suppressed compared to the case where all the branch boats are connected as in the example shown in FIG. . The torque curve γ of the present invention is shown in FIG. 4, and the torque curve γ is close to the torque curve α when the branch boat is not connected (1 degree).
Regarding the introduction of air for air-fuel ratio compensation, EGR gas controlled by an EGR valve 49 is circulated from the exhaust manifold through an EGR passage 50 to the first balance tube 46 via an EGR gas supply passage 48. Ru. Also,
Air for air-fuel ratio compensation is also introduced into the first balance tube 46 via the EGR gas supply passage 48 via the air cleaner.

At this time, since the EGR gas supply passage 48 is provided at or near the center of the first balance tube 46, the tendency for the EGR gas to flow into each intake manifold 22, 23 is the same, and as shown in FIG. As shown in the figure, since the unbalanced region of the flow rate when the throttle valve is fully open is controlled, the air-fuel mixture distribution to each cylinder is improved. Note that when the throttle valve is fully open, control of EGR residue or air-fuel ratio compensation air is not performed.

Furthermore, at [ff1f7] of the first balance tube 46, since the pulsation has already been attenuated by the second balance tube 47, the first balance tube 46
The influence of intake pulsation on the distribution of EGR gas or air-fuel ratio compensation air introduced into the engine can be reduced. Therefore, better distribution to the cylinders is promoted.

As is clear from the above description, in the intake manifold of the present invention, the intake manifold for each carburetor is communicated with the intake manifold at a position directly below the carburetor and at a position remote from the carburetor, and also directly below the carburetor. Since the EGR gas supply passage is connected to the balance tube that communicates at the position, the present invention can improve the distribution of EGR gas to each cylinder, reduce pulsation during idling, and reduce pulsation when the throttle valve is fully opened. This provides the advantage that it is possible to effectively suppress the unbalance of the flow rate of the engine, improve the output of the engine, etc.

In the above description, the intake manifold connected to a downdraft carburetor was taken as an example, but it may also be an intake manifold connected to a side draft carburetor. The present invention is not limited to, but may be a six-cylinder intake manifold in which three branch boats are connected to each carburetor of a two-carrier type, and may also be a multiple-carrier type carburetor other than a two-carrier type. These are included in the technical idea of the present invention.

[Brief explanation of the drawing]

Figure 1 is a plan view of an intake manifold with a balance tube for a fixed venturi type multiple carburetor as a prior art. Figure 2 is the engine rotational speed in the intake manifold with balance tube for a multiple carburetor shown in Figure 1. Figure 3 shows a cross-sectional view when all intake boats are connected through a balance tube, Figure 4 shows a comparison between when a balance tube is installed and when it is not installed. A characteristic diagram of engine speed and torque. FIG. 5 is a plan view of a balance tube communication type intake manifold previously proposed by the applicant. FIG. 6 is a plan view of an intake manifold according to an embodiment of the present invention. , Fig. 7 is a sectional view of the intake manifold shown in Fig. 6 and its vicinity, Fig. 8 is a characteristic diagram of the engine rotation speed and intake flow rate of each carburetor of the engine intake system with the intake manifold shown in Fig. 6 installed, It is. 21... Intake manifold (whole) 22.23.
... Intake manifold (part) connected to each carburetor 24.25 ... Carburetor 26.27 ... Riser section 28.29 ... Collection section 30.31... Branch part 32.33.34.35... Branch boat 36.
...Cylinder head 37...Cylinder head intake port 1-38.
... Throttle valve 39 ... Venturi section 41 ... Suction piston 44 ... Vent 46 ... First balance tube 47 ...
... Second balance tube 48 ... EGR gas supply passage 49 ... EGR valve 50 ... EGR passage 53 ... Air-fuel ratio compensation air supply passage 49 ... EGR valve 50 ... EGR passage 53 ... Feedback passage Fig. 1 Fig. 2 Elegance training number N Middle mchi Fig. 3 Fig. 4 May 22nd, Commissioner of the Japan Patent Office, 1. Indication of the case, Patent Application No. 116189, filed in 1982. 2. Title of the invention: Intake manifold 3. Relationship with the person making the amendment. Patent applicant address: 1 Toyota-cho, Toda City, Aichi Prefecture. Name (320) Toyota Motor Corporation Morita Masaton Representative Masatoshi Morita 4, Agent 107 Address 1-7-5 Akasaka, Minato-ku, Tokyo @ Showa Building 6,
Target of amendment Drawing 7, contents of amendment (1) Fig. 7 of the drawing is amended to Fig. 7 attached to this written amendment. 8. 1 copy of catalog drawing of attached documents

Claims (2)

[Claims] (1) In the intake manifold of a multi-cylinder engine connected to a variable venturi type multiple carburetor, the intake manifold connected to each carburetor is connected to the carburetor through a first balance tube at a position directly below the carburetor. communicated by a second balance tube at a more distant position,
EG to the first balance tube installed directly below the carburetor.
An intake manifold characterized in that an R gas supply passage is connected to the intake manifold. (2) The intake manifold according to claim 1, wherein an air-fuel ratio compensation air feedback passage is also connected to the EGR gas supply passage.