JPS6198958A - Intake passage device of multi-cylinder engine - Google Patents

Abstract

PURPOSE:To improve a distribution characteristic of fuel, by forming a plurality of passage to be divided on the bottom surface of an intake passage part introducing a mixture in a direction distant from an engine in accordance with a number of passages in the side of a fuel supplying means, in the case of an engine equipping an intake manifold of U turn type. CONSTITUTION:An intake manifold 1, setting a twin carburetor onto a mounting flange 2, has a primary side and a secondary side port 3, 4. The intake manifold 1 in the downstream side of these ports 3, 4 has an intake passage part 8, comprising a riser part 6 and a communication path 7 extending in a horizontal direction, and a branch part 10, in which a branch passage 9a, 9b collects in the upstream end, while the branch passage 9a, 9b, branching from the branch part 10 and performing a U turn, is connected with each intake port of an engine 5. Here an intake passage device, providing a partition 21 in the intake passage part 8 in a plane containing its center line C8, thus forms a primary side passage 22 and a secondary side passage 23 to be divided in the intake passage part 8.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to improving fuel distribution in a multi-cylinder engine with a so-called U-turn intake manifold.

<Prior Art> A mixture of fuel and air is once guided away from the engine via an intake passage to a branching part, and then from the branching part to the engine via a plurality of branching passages that make U-turns in different directions. A so-called U-turn type intake system, which is configured to introduce fuel into each cylinder, is known as a means for improving fuel distribution. This is shown in Figure 6 (A), CB)
4742).

In the figure, the intake manifold 1 is connected to the carburetor mounting flange 2.
has. The carburetor (not shown) is attached to the carburetor mounting flange 2.
It is placed and fixed on top. The carburetor is a two-channel type having passages on a primary side and a secondary side, and a primary side port 3 and a secondary side port 4 that communicate with each other are connected at the upstream end of the intake manifold 1 in the direction of the cylinder row of the engine 5. are arranged in parallel.

The intake manifold 1 on the downstream side of the primary side and secondary side ports 3 and 4 is an intake passage section consisting of a riser section 6 at the bottom of the carburetor and a communication passage 7 extending from the riser section 6 in a direction horizontally away from the engine 5. 8, a branching part 10 to which the communication passage 7 is connected and the branching passage parts 9a and 9b gather at the upstream end thereof, and a branching part 10 branching from the branching part 10 and making a U-turn so that there is a cylinder row in the direction of vehicle movement. It has the branch passage section 9a extending toward the front side of the engine 5 disposed therein, and the branch passage section 9b extending toward the rear side. Branch passage section 9
a and 9b each branch into two branches and communicate with the intake ports of each cylinder.

According to this configuration, the mixture of fuel and air supplied from the carburetor passes through the primary side port 3 or through the primary side port 3 and the secondary side port 4 to the riser part 6, and then passes through the communication path in the direction away from the engine 5. 7 and reaches the branch 10.

The mixture that collides with the wall of the branching part 10 branches back and forth,
It is introduced into each cylinder via branch passages 9a and 9b.

According to this flow of the air-fuel mixture, compared to a normal intake manifold that is not a U-turn type, such as a so-called banana type or tournament type, which smoothly guides the mixture from the riser part 6 to the branch passage without leaving the engine 5, the mixture is Since the air from the riser section 6 collides with the inner wall of the branch section 10 and is guided to each branch passage section 9a, 9b, it is generally said that the U-turn type intake manifold has higher fuel distribution performance. .

<Problems to be Solved by the Invention> However, in the conventional U-turn type intake manifold, the central axis C3 of the primary side port 3, the central axis C4 of the secondary side port 4, and the central axis C8 of the intake passage portion 8 are are offset from each other, so the air mixture flow in the communication passage 7 becomes a swirling flow as shown in the figure. The flow pattern of the swirling flow of the air-fuel mixture changes depending on the engine operating condition.

On the other hand, during high-load operation of the engine with a relatively large fuel flow rate or when the engine is operated at low temperature, most of the fuel flows along the inner wall of the intake passage, forming a so-called liquid film flow, which is dragged by the air mixture flow and flows into the engine 5. Therefore, when the flow pattern of the air-fuel mixture changes depending on the operating condition as described above, the outflow pattern of fuel from the communication passage 7 to the branch part 10 changes, and the fuel flows to each branch passage part 9a, 9b. There is a risk that a difference will occur in the amount of fuel and the fuel distribution to each cylinder will deteriorate.

When such a phenomenon occurs, it becomes difficult to form the desired mixture ratio between each cylinder and combustion deteriorates, which inevitably leads to deterioration of exhaust properties and fuel efficiency.In addition, the output torque decreases, resulting in a worsening of the feeling of acceleration or surges. This tends to lead to deterioration in drivability, such as a decrease in Such inconveniences occur not only in carburetors having two passages, a primary side port and a secondary side port, but also in fuel supply means having a plurality of passages in general.

In view of the above-mentioned conventional disadvantages, the present invention provides a U-turn type intake passage device in which a fuel supply means having a plurality of passages is connected upstream, in which a liquid film flow led from the plurality of passages is independently guided to a branch part. It is an object of the present invention to provide an intake passage device that always has good fuel distribution performance regardless of changes in the flow pattern of the air-fuel mixture according to engine operating conditions.

Means for Solving Problems> To this end, in the present invention, in a U-turn type intake passage device in which a fuel supply means having a plurality of passages is connected upstream, an upstream end communicates with the plurality of passages and an intake passage is provided. A partition wall that stands up at least on the bottom surface of the intake passage section that guides the air in a direction away from the engine and introduces it into the branch section is provided on an extended surface of the partition wall that partitions the plurality of passages on the fuel supply means side.

As a result, the liquid film flow of the fuel passing through the intake passage is guided by the partition wall and guided through a fixed path to a predetermined location of the branch portion, without being influenced by the flow pattern of the air-fuel mixture. Therefore, the guided liquid fuel is distributed approximately equally to each branch passage.

<Example> Examples of the present invention will be described below based on the drawings. Elements similar to those of the conventional example shown in FIG. 6 are designated by the same reference numerals and their explanations will be omitted.

In the first embodiment shown in FIG.
The carburetor mounted and fixed on the carburetor mounting flange 2 of the engine 5 is a two-channel carburetor having a primary side passage and a secondary side passage arranged in parallel in the cylinder row direction of the engine 5. A partition wall 21 is provided in the intake passage section 8 within a plane including the partition wall between the passages and the center line C6 of the intake passage section 8,
Thereby, a primary side passage 22 and a secondary side passage 23 are formed separately on both sides thereof.

The partition wall 21 also serves as a partition wall between the primary port 3 and the secondary port 4 shown in FIG.
The riser section 6 is completely divided into two parts by the partition wall 21, but in the communication path 7, the partition wall stands up from the bottom surface 7a by a predetermined height, and above it, the primary and secondary side paths 22 and 23 are connected. A mutually communicating space 24 is formed. The height of the partition wall 21 in the communication path 7 gradually decreases toward the branch portion 10.

Primary and secondary side passages 22 of the intake passage section 8.
The center line C3 of 23 is aligned with the center line of the primary side passage and the secondary side passage of the corresponding carburetor, and at the outlet of the intake passage section 8, the center line C3 of the primary and secondary side passage 22, 23 is aligned with the center line of the primary side passage and the secondary side passage of the corresponding carburetor. C8 is oriented in a direction substantially perpendicular to the center line C3 of the branching portion 10. In other words, the primary and secondary side passages 22.
The relative positions of the branch portion 23 and the branch portion 10 form a substantially T-shape.

According to this configuration, intake air sent from the primary side passage in the upstream fuel supply means is independently introduced into the primary side passage partitioned by the partition wall 21 of the intake passage section 8, while the intake air is introduced into the primary side passage partitioned by the partition wall 21 of the intake passage section 8, while The passage is similarly introduced independently into the secondary side passage 23 of the intake passage section 8. Therefore, the liquid film flow of fuel that has flowed down along the intake flow hits the partition wall 21 and collects at the corners 22a and 23a formed by the partition wall 21 and the bottom surfaces of the primary and secondary side passages 22. It is guided along the lower part to the branching part 10.

On the other hand, as the fuel flow floating in the air goes downstream of the intake passage section 8, the height of the partition wall 21 decreases, and a mutually communicating space 24 is formed above the partition wall 21.
The mixture can be promoted through the upper part of the air-fuel mixture.

As is clear from the above phenomenon, a liquid film fuel flow is generated that collects at the bottom of both sides of the partition wall 21, so that the primary side passage 22
Even if the flow pattern of the intake air in the secondary side passage 23 changes depending on the operating condition, the liquid film flow of the fuel does not change and flows from the approximate center of the communication passage 7 to the center of the branch portion 10 at a substantially right angle. leaks into As a result, each branch passage section 9
The amount of fuel distributed to a and 9b is approximately equal.

The length of the partition wall 21 is preferably such that it extends to the downstream end of the communication passage 7 connected to the branch portion 10, but the height of the partition wall 21 is determined from the bottom surface 7a of the intake passage portion 8 as shown in FIG. The partition wall 21 may be erected over the entire area up to the upper surface 7b, or, as shown in FIG. You may also do so.

In the embodiment shown in FIG. 3, the height of the partition wall 21 is configured to gradually decrease toward the downstream side, and substantially the same effect as in the embodiment shown in FIG. 1 is achieved.

In the embodiment shown in FIG. 3, the primary side passage and the secondary side passage of the fuel supply means and the intake passage section 8
Primary side passage 22 and secondary side passage 2
3 cannot be reliably independent because there is no partition wall at the upstream end of the intake passage section 8, but there is virtually no problem in this respect.

Another embodiment of the present invention shown in FIG.
, '9b A distribution projecting wall 31 as a distribution member is erected along the center of the bottom of these sections. The distribution projecting wall 31 extends perpendicularly to the partition wall 21, and in the embodiment shown in FIG. The liquid film flow collides with the distribution projecting wall 31 at a substantially right angle and is distributed to the front side and rear side of the engine. At this time, the distribution projecting wall 31 is connected to the branch portion 10 and the branch passage portions 9a and 9b.
Since the branched liquid film flow extends approximately at the center bottom of the branch passages 9a and 9b, it flows through the downstream ends of the branch parts 9aa and 9ab (rear side branch passage part 9).
Although b is omitted, the liquid film fuel flow is well distributed and supplied. On the other hand, the mixture of atomized fuel and air that does not form a liquid film flow flows through the space 24 above the partition wall 21 and also crosses over the distribution projection wall 31 to contact the inner wall of the branch portion 10 on the side farther from the engine 5. , where it is distributed and supplied to the rear and engine sides. Such a mixed air flow originally has good distribution properties. If the distribution projecting wall 31 is not provided as in this embodiment, the fuel liquid film flow flowing under the partition wall 21 collides with the inner wall 10a of the branch portion 10 on the side far from the engine 5, and from this The liquid film flow is divided into the front and rear sides, but since the divided liquid film flow tends to flow along one side wall of the branch passages 9a and 9b, it is shown as 9 in the figure.
This makes it difficult to flow into the ab branch passage, resulting in poor distribution. The distribution projecting wall 31 of this embodiment prevents this as described above.

The length of the distribution projecting wall 31 is determined to be the best value depending on the length, shape, etc. of each branch passage section 9a, 9b and 9aal9ab.

The distribution projecting wall 31 as the distribution member in the above embodiment does not necessarily have to be a projecting wall. In other words, it is sufficient to capture the fuel liquid film flowing along the bottom of the partition wall 21 and guide it toward the center of the bottom wall of each branch passage section 9a, 9b, so that it can be distributed as shown in FIG. It is clear that the distribution groove 32 may be formed as a member.The distribution groove 32 captures the fuel liquid film flow flowing along the partition wall 21, and
The air is guided by the air mixture flow and distributed to the front and rear sides of the engine, and is guided toward the center of the bottom of the branch passages 9a and 9b, resulting in the same effect as that of the distribution projecting wall 31.

It is preferable that the distribution means including the distribution protruding wall 31, the distribution groove 32, etc. be formed approximately at right angles to the partition wall 21. If the shape is slanted, the liquid fuel will flow through the distribution means in a direction that is easier to flow under the influence of the velocity of the liquid film fuel flow and the intake air flow. (However, if the manifold without the distribution means has a tendency to deviate in one direction due to inertia or position, the distribution can be made uniform as a whole by adjusting the angle of the distribution means in the opposite direction.) can be achieved.

) Further, as seen in each of the above embodiments, the primary side passage and the secondary side passage on the fuel supply means side, and the primary side passage 22 . The center lines of the secondary passages 23 are made to coincide with each other. As a result, the intake air flow from the fuel supply means to the intake manifold 20 flows approximately along the center line of each passage without interfering with each other in the primary side passage and the secondary side passage, so that it flows along the inner wall being dragged by this intake air flow. The liquid film flow fuel is also reliably collected at the upright portions of the partition wall 21, that is, at the corner portions 22a and 23a at the bottom of the partition wall, thereby promoting the effect of flowing the fuel substantially parallel to the bottom center of the intake passage portion 8.

Incidentally, in the embodiment shown in FIG.
It is designed to be smoothly connected to the bottom walls of parts a and 9b. Therefore, the liquid film fuel is reliably stored in the center of the distribution groove 32, and is more smoothly guided to the branch passages 9a and 9b.

In the embodiment described above, a carburetor is connected upstream of the intake passage device according to the present invention as a fuel supply means, but a type provided with a fuel injection valve, for example, a single point injection system, can have the same effect. Further, the orientation of the engine, the arrangement positions of the primary and secondary side passages, and the shape of the branch passage portion are not critical. The branch passage section may be of a U-turn type that branches from the branch section in different directions. In addition, as a conventional example, a type having a primary side port and a secondary side boat at the upstream end of the intake manifold is shown as an example, but there are also intake manifolds in which the intake passage section is not branched into the primary side and the secondary side like this. , the present invention is fully applicable to such an intake manifold. Further, in the above embodiment, the intake passage is divided into two by the partition wall and branched into two passages, the primary side passage and the secondary side passage, but it is also possible to branch into three or more plural passages.

<Effects of the Invention> As described above, according to the present invention, in an intake passage device consisting of a U-turn type intake manifold, etc., the air-fuel mixture is guided in a direction away from the engine according to the number of passages on the fuel supply means side. Since a partition wall is installed on the bottom of the passage to divide it into a plurality of passages, the fuel liquid film flow flowing through the intake passage does not flow along the inner circumferential wall of the entire intake passage, but is collected at the bottom of the partition and is divided into a plurality of passages. Since the fuel liquid film flow at the branch section is collected at a predetermined position, it can be guided and supplied to each branch passage section with good distribution. Therefore, the fuel distribution characteristics of the U-turn type intake passage device are further improved, thereby making it possible to eliminate variations in the mixture ratio between cylinders and control the mixture ratio to be uniform, thereby improving combustion. Therefore, exhaust properties and fuel efficiency are improved, and drivability such as acceleration characteristics and surge reduction is improved.

[Brief explanation of the drawing]

FIG. 1 shows a first embodiment of the present invention, FIG. 1(A) is a plan view, FIG. 1(B) is a sectional view taken along line IB-IB in FIG. 1(A), and FIG. 1(C) is a plan view. is an IC-IC sectional view of FIG. 1(B), and FIG. 2 is a cross-sectional view of FIG. 1(B) showing another embodiment of the present invention.
FIG. 3 is a diagram corresponding to FIG. 1 (B) showing still another embodiment of the present invention, FIG. 4 is a diagram showing another embodiment of the present invention, and FIG. 4 (A) is a plan view; Figure 4(B) is IVB-I as above.
VB sectional view, FIG. 5 shows still another embodiment of the present invention,
FIG. 5(A) is a partially cutaway plan view, FIG. 5(B) is a VB-VB sectional view of the same as above, and FIG. 6 is a conventional suction 5... engine 6... riser portion 7.・Communication path 8・・
・Intake passage section 9a, 9b, 9aa
, 9ab-... Branch passage section 10... Branch section
20... Intake manifold 21... Bulkhead 22.
...Primary side passage 23...Secondary side passage 22a, 23a...Corner portion 31...Distribution projecting wall 32...Distribution groove Patent applicant Nissan Motor Co., Ltd. Representative Patent attorney Fujio Sasashima No. Figure 2 Figure 4 j (B) (A') i'=VB Figure 6

Claims (2)

[Claims] (1) an intake passage portion whose upstream end communicates with a fuel supply means having a plurality of passages and whose downstream end extends in a direction away from the engine; and a branch portion connected to the downstream end of the intake passage portion;
A multi-cylinder engine comprising: a plurality of branch passages that make U-turns in different directions from the branch part; and a partition wall that stands up at least on the bottom surface of the intake passage part and partitions the plurality of passages. Intake passage device. (2) The multi-cylinder according to claim 1, wherein the branch part is a branch part having a distribution member that distributes the air-fuel mixture introduced from the intake passage to each branch passage part. Engine intake passage device.