JPS6196127A - Intake device of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent liquid fuel from attachment to an ignition plug by providing an ascending grade portion on the way of a branched path portion facing the ignition plug while forming the intermediate portion of the other branched path facing an exhaust valve at a lower position than the ascending grade portion. CONSTITUTION:An intake port 11 has a branched path portion 11A reaching an intake valve 3A opposed to an intake valve 5 and a branched path portion 11B reaching an intake valve 3B opposed to an ignition plug 6. Then, the branched path 11A is gradually lowered from a port inlet portion 13 to communicate to a combustion chamber 2. On the other hand, the branched path portion 11B is formed with an ascending grade portion 15 having the bottom surface inclined upward from an inlet portion 13 to the proximity of a branched portion 12 and the downstream side of the branched point 12 inclined steeply so that said path 11B is opened to the combustion chamber 2 with the downstream side of the branched point 12 being steeply inclined to give the directional property approximating to the perpendicurarlity along an intake valve stem to the center line. Thus, liquid fuel never flows into the branched path portion 11B so that the ignition plug 6 is prevented from attachment of the liquid fuel.

Description

Detailed Description of the Invention (Industrial Application Field) This invention relates to an intake passage for an internal combustion engine, and more specifically, to an improvement in the shape of an intake port of a multi-valve reciprocating internal combustion engine having a plurality of intake valves per cylinder. Regarding.

(Japanese technology) cylinder perforation for the purpose of improving suction efficiency and output characteristics)
Internal combustion engines equipped with two intake valves are being adopted in general passenger cars, but what about when high-speed performance is not required and FC is not required? It is considered that the number of exhaust valves is one in order to balance the power supply, and therefore, there are some models that adopt a three-valve structure with three intake and exhaust valves in total.

One example of this type of three-valve engine is the one shown in FIG.

This is a 7 dollar combustion chamber part 2 to Schilling as shown.
Two intake valves 3A13B having substantially the same diameter as each other are provided, and a so-called siamic-shaped intake port 4 having corresponding passages i4A and 4B branched from the middle is formed.

By the way, in a configuration in which the two intake valves 3A and 3B are arranged in parallel and only one exhaust valve is provided, it is preferable to place the ignition plug in the center of the combustion chamber 2 with emphasis on combustion efficiency. If this is done, the effective diameter of the exhaust valve will not be sufficient, which will be disadvantageous in terms of exhaust efficiency. Therefore, as shown in the figure, the exhaust valve 5 and the ignition plug 6 are also parallel to each other, that is, the exhaust valve 5 is located in front of one of the intake valves 3A, and the ignition valve is placed in front of the intake valve 3A. The plug 6 is located in front of the externally operated intake valve 3B. (Refer to Japanese Patent Application Laid-Open No. 59-93926.105925 for a known example of a three-valve engine.) (Problems to be Solved by the Invention) However, according to the above valve arrangement, the ignition plug 6 is connected to the suction port 4. Since the ignition plug 6 is located approximately on the extension of one of the branch passages 4B, during low-temperature operation where the fuel in the intake air is supplied in a substantially liquid state, the ignition plug 6's ? 1ffi portion is exposed to the liquid fuel flowing into the combustion chamber portion 2 via the port branch passage portion 4B. Therefore, at low temperatures, discharge is inhibited by the so-called capri, resulting in poor startability, resulting in the problem that stable idling and drivability are difficult to obtain even after starting.

The present invention has been made with the aim of solving the above-mentioned conventional problems.

(Means for solving the problem) In order to achieve the above object, this invention focuses on the fact that most of the liquid fuel flows along the lower wall surface of the intake passage and the intake port, and as described above, At least 62 intake valves and at least one exhaust valve are provided per cylinder, and an intake port having a passage section branching from the middle is formed corresponding to each of the two intake valves, and at least one In an internal combustion engine in which α powder is disposed in front of a branch passage portion and an exhaust valve is disposed in front of another branch passage portion, an ascending slope portion is provided in the middle of the branch passage portion facing the α powder, and The middle part of the branch passage part of the pond facing the exhaust valve is formed at a lower level than the upward slope part.

(Function) According to the above configuration, the fuel that enters the intake port in a liquid state at a low temperature tries to be diverted to each branch passage along the lower part of the port, but the branch passage on the ignition plug side has an upward slope along the way. In addition, the part of the branch passage on the exhaust valve side that corresponds to the upward slope part is at a lower level, in other words, the branch passage on the exhaust valve side is connected from the branch passage on the ignition plug side to the branch passage on the exhaust valve side. Since the slope slopes downward toward the exhaust valve, most of the liquid fuel is forced toward the exhaust valve side branch passage.

Furthermore, even if a certain amount of liquid fuel travels through the ignition plug side branch passage, the second branch passage will have an upward slope in the middle.
Due to this, the part just before reaching the combustion chamber is a steep slope that almost follows the intake valve stem.By changing the direction along this steep slope, the velocity component is mainly in the vertical direction. After the fuel flow enters the combustion chamber, it does not proceed in the direction of the σ powder.

Therefore, the ignition plug can exhibit stable ignition performance without being exposed to liquid fuel.

Next, embodiments of the present invention will be described based on the drawings. Note that substantially the same parts as in FIG. 5 are designated by the same reference numerals.

(Example) In the m1 diagram, 10 is an intake manifold old, 11 is an intake port that introduces the intake air flow from the intake manifold 10 into the Iso rlJ combustion chamber section 2, and 11A is an exhaust valve branched from the middle of the intake port 11. IIB is a branch passage section leading to the first intake valve 3A for the spark plug 6, and IIB is a branch passage section leading to the second intake valve 3B for the spark plug 6.

The two branch passage sections 11A and IIB are symmetrically branched from each other's branch point 12 on a plane, but when viewed from the side,
As shown in FIG. 2, the branch passage section 11A on the exhaust valve 5 side gradually descends from the port inlet section 13 and reaches the combustion chamber 2, whereas the branch passage section 11B on the spark plug 6 side has its bottom surface. becomes an upward slope section 15 that slopes upward from the inlet section 13 to the vicinity of the branch point 12, and the downstream side of the branch point 12 is steeply sloped, and its center line is approximately vertical along the intake valve stem 16. It opens into the combustion chamber part 2 with a characteristic.

Based on such an intake port shape, among the liquid fuel that has flowed into the intake port 11 along the bottom surface of the intake manifold old 10, the fuel that is flowing toward the spark plug side branch passage section 11B is directed toward the upward slope section. At 15, its momentum in the advancing direction is reduced, and at the same time, it is urged by gravity toward the exhaust valve side branch passage section 11A located at a lower position. Therefore, most of the liquid fuel is introduced into the exhaust valve side branch passage section 11A.

Furthermore, if liquid fuel enters the spark plug side branch passage section 11B, this fuel changes its direction in a substantially vertical direction together with the intake air flow and enters the combustion chamber section 2 and the cylinder.

Therefore, the liquid fuel does not come into direct contact with the ignition plug 6, and stable ignition performance can be guaranteed.

Needless to say, the atomized or vaporized fuel is equally divided into the two branch passages 111111A and IIB together with the intake air and enters the sill folds.

FIG. 3 shows another embodiment of the present invention, in which the side shapes of the branch passage portions 11A and IIB of the suction bow 11 are the same as in FIG. The inlet portion 13 is formed offset to the exhaust valve 5 side,
The intake manifold old 10 and the exhaust valve side branch passage section 11A are arranged in an IF-straight line. As a result, the liquid fuel from the intake manifold 10 can be introduced exclusively into the JIFpA valve side branch passage section 11A using its inertia, and the amount of liquid fuel intruding into the spark plug side branch passage section 11B can be increased. can be further reduced.

Furthermore, in each of the above embodiments, the lower edge of the opening of the spark plug side branch passage section 11B viewed from the port entrance section 13 (tI43
By forming a stepped portion 18 or a groove 19 as shown in FIGS. 4(A) and 4(B) along point 0 in the figure, the ignition plug side branch passage portion 11B is formed along the bottom surface of the port. The liquid fuel that tends to flow can be more reliably suppressed.

(Effect of R-light) As described above, according to the present invention, liquid fuel is prevented from flowing into the branch passage of the intake port facing the spark plug, and the liquid fuel adheres to the a-contact and α-ignition powder. Since this is avoided, the ignition performance of the ignition plug can be maintained at a good level.

Therefore, it is possible to improve the startability of the multi-valve internal combustion engine at low temperatures and the driving performance after starting, and to avoid deterioration in fuel efficiency and exhaust composition caused by poor ignition or irregular combustion.

Brief Description of Joints FIG. 1 is a bottom WJ diagram of one embodiment of the present invention, and FIG. 2 is a sectional view taken along A-Al1. FIG. 3 is a bottom view of the embodiment of the pond, and FIGS. 4(A) and CB) are cross-sectional views showing an example of the shape of the portion along the line B-B#a.

Figure fjS5 is a bottom view of the conventional example.

1... Schilling head, 2... Combustion chamber part, 3A, 3
B...Intake valve, 4,11...Intake bow), 4A, 4
B.

11 A, 11 B... Branch passage section of suction port, 5
...Exhaust valve, 6...Ignition plug, 15...Uphill slope section.

Patent applicant: Nissan Motor Co., Ltd. Figure 1

Claims (1)

[Claims] At least two intake valves and at least one exhaust valve are provided per cylinder, and an intake port having a passage branching from the middle corresponding to each intake valve is formed,
and an internal combustion engine in which an ignition plug is disposed in front of at least one branch passage, and an exhaust valve is disposed in front of another branch passage, wherein an upwardly sloped part is provided in the middle of the branch passage facing the ignition plug; An intake system for an internal combustion engine, characterized in that an intermediate portion of the other branch passage portion facing the exhaust valve is formed at a lower level than the upward slope portion.