JPS60162017A - Intake device for engine - Google Patents

Abstract

PURPOSE:To prevent the shock of the changeover from the low-load run of an engine to its high-load run, by curving the second-intake-port-side wall of an auxiliary intake passage, from a second intake port toward a first intake port, to maintain the swirling performance of the engine in its low-load run. CONSTITUTION:The upstream opening 13a of an auxiliary intake passage 13 is located at the bottom of an intake passage 8 upstream to a shutoff valve 12, while the downstream opening 13b of the passage 13 is located upstream to the downstream end 9a of a partition wall 9. The auxiliary intake passage 13 is slowly curved across a center line l. The second-intake-port-side wall 13c of the auxiliary intake passage 13 is curved from a second intake port 5 toward a first intake port 4. The upstream opening 13a of the auxiliary intake passage 13 is provided at a common passage portion, in which the intake passage 8 is not ramified, to have a large open area. The cross-sectional area of the passage 13 is thus enlarged to prevent the shock of the changeover from the low-load run of an engine to its high-load run.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is directed to an engine intake system, in particular, to open a plurality of intake ports such as two ports into a combustion chamber of the engine, and to open the same to each intake port. This invention relates to a type of intake device equipped with an intake valve that opens and closes.

(Prior art) Conventionally, in a reciprocating engine, two intake ports with approximately equal opening areas are opened in accordance with each combustion chamber to ensure a large opening area, and a The intake passage formed at The intake structure of engines designed to increase output is well known.

Such a two-point intake structure is advantageous in that it can achieve high output during high-load operation, but on the other hand, during low-load operation with a small amount of intake air, the intake flow velocity weakens and combustibility deteriorates. However, it has disadvantages in terms of fuel efficiency and emissions.

In order to eliminate this drawback, a low-load intake passage and a high-load intake passage with a shutter valve interposed are connected to the two intake ports in 1. When the engine is operating at low load, the shutter valve is closed. It is known that air is taken only from the low-load intake passage (for example, see Japanese Patent Laid-Open No. 56-44419).

However, such measures are not necessarily effective as low-load countermeasures. In other words, the opening area of the two intake ports was originally designed to be maximized in order to achieve high output, so even if only one intake port is used, during extremely low load operation where the amount of intake air is small, the opening area will be reduced. is still too large to effectively improve the intake air flow velocity, making it impossible to effectively form the swirl that is essential for improving combustibility.

It seems that this problem can be solved by narrowing down the passage area of the low-load intake passage, as disclosed in Japanese Patent Application Laid-open No. 11S (1986-146), but in that case,
If you do not increase the passage area of the high-load intake passage too much, you will be able to achieve the original purpose of increasing output, but if you actually increase the passage area, the difference between the passage area of the low-load intake passage and The balance becomes large, causing a so-called switching shock when switching from low load to high load, which opens the low-load intake passage, and at high loads, intake air concentrates in the high-load intake passage where there is less intake resistance. In reality, there is a contradiction in that an effective intake passage area cannot be secured to achieve high output. Furthermore, for the purpose of achieving high output, the boat connection part of the intake passage is formed along the axial direction of the combustion chamber, as described above, so that by increasing the intake air velocity, a high-velocity flow flows inside the combustion chamber. Even if J is generated as an effective swirl along the circumferential direction of the combustion chamber,
! ! , not done. Therefore, there is a problem in that the intake air flow is attenuated early in the compression stroke.

On the other hand, if you try to increase the flow velocity and restrict the low-load intake passage too much, the load range that can be covered will be limited. It is also necessary to supply intake air from the In that case, the two intake ports are formed opposite to each other with respect to the horizontal center line of the combustion chamber, so that the intake air flow taken in from the low-load intake boat and the intake flow taken in from the high-load intake boat are different. If the swirls collide with each other, the swirl is further weakened, if not eliminated, making it difficult to ensure good combustibility due to the swirl.

As shown in Figure 1 above, narrowing down the low-load intake passage and the intake port connected to it not only contradicts the purpose of achieving high output, but also causes various new problems. do.

The present applicant has discovered that the two-intake point system, which aims to increase engine output, is effective in improving combustibility within the combustion chamber during low-load operation of the engine without substantially changing the two-intake point system. Japanese Patent Application No. 58-176,776 has already proposed an engine intake system having an intake structure that generates a swirl.

The proposed invention relates to an intake system for an engine in which a plurality of intake ports are respectively opened into combustion chambers of an engine, and each intake port is opened and closed by an intake valve. An on-off valve is disposed inside the engine, and the on-off valve is closed during low-load operation and opened during high-load operation. Mo”-
The basic feature is that an auxiliary intake passage is provided, which branches off from the bottom of the air intake passage, is connected to any one of the intake boats, and is smaller in area than the intake passage.

That is, in this invention, during low-load operation of the Ennon when the on-off valve is closed, intake air flows exclusively from the auxiliary intake passage formed at the bottom of the intake passage through the intake port to which this passage is connected at a high flow rate. Supplied to the combustion chamber of the engine.

In that case, the auxiliary intake passage is located at the bottom 11111 of the intake passage.
This naturally forms a shallow angle in line with the mating surfaces of the cylinder head and cylinder block, and the intake air flowing into the combustion chamber generates a swirl that swirls in the circumferential direction of the combustion chamber. Furthermore, during high-load operation of the engine when the on-off valve is opened, intake air is drawn in from a plurality of intake ports with high filling efficiency, and the original high output can be guaranteed.

Therefore, according to the present invention, the combustibility during low-load operation can be improved without sacrificing the original purpose of the two-intake engine system, which is to increase engine output.
Although it is possible to improve fuel efficiency and emission performance, there is still room for improvement.

One of them is the above-mentioned problem of switching shock that may occur when switching from a low load to a high load. In other words, while the on-off valve is opened from the low-load region where the auxiliary intake passage is used exclusively, when moving to the high-load region, a large amount of intake air flows into the combustion chamber from each intake boat at once, so the charging amount decreases. increases rapidly, causing a kind of torque shock.

(Objective of the Invention) The object of the present invention is to expand the low load range that can be covered with the on-off valve closed while maintaining the swirl during low-load operation. The purpose is to prevent the above-mentioned cut-off shock by ensuring a sufficient amount of intake air when the valve is closed so as to minimize the amount of intake air when the valve is closed.

(Structure of the Invention) Therefore, the present invention provides a plurality of intake boats that open into a combustion chamber, an intake passage whose branch ends are connected to each intake boat and which are branched downstream, and a branch portion of the intake passage. An on-off valve that is provided further upstream and closes at low loads and opens at high loads, and an auxiliary intake passage that branches from the on-off intake passage and is connected to one of the intake boats downstream from the on-off valve. The intake boat opening of the auxiliary intake passage is opened upstream of the branch part of the intake passage, and the passage wall on the north side of the intake boat of the auxiliary intake passage is connected to the intake port of the auxiliary intake passage. It is formed so as to be inclined from the bow 1 toward the intake port side where the auxiliary intake passage is open 1''.

With this setting, the intake boat opening of the auxiliary intake passage can be provided in the common passage before the intake passage branches, so it is possible to secure a large opening area, especially the width dimension, and the auxiliary intake A large cross-sectional area of the passage can be ensured, and the operating range that can be covered by the auxiliary intake passage can be expanded.

At the same time, as mentioned above, since the auxiliary intake passage is formed to be inclined toward the one intake port side where the auxiliary intake passage is opened, it flows down the auxiliary intake passage and from one intake boat to the combustion chamber. The intake air flow entering the combustion chamber is directed in the circumferential direction of the combustion chamber, thereby creating a strong swirl within the combustion chamber.

(Effects of the Invention) Therefore, according to the present invention, the load range that can be covered with the on-off valve closed can be expanded to the high load side while maintaining swirl performance, and the transition from low load to high load can be achieved. This makes it possible to effectively prevent the so-called switching shock at the time of switching.

(Example) Examples of the present invention will be described in more detail below.

As shown in FIG. 1, in the combustion chamber 2 of one cylinder 1 of the engine E, there is a first cylinder 2 having approximately the same diameter, which is approximately symmetrical with respect to the center line in the width direction of the cylinder block of the engine E. The second intake boats 4, 5 are opened 1], and the first intake boat 4, 5 is opened 1], and the first intake boat 4, 5 is opened 1], and the first intake boat 4, 5 is opened 1]. An air port 6.7 is opened at a position facing the second air intake boat 4.5.

1st. The intake passage 8 that supplies intake air to the second intake boats 4 and 5 gradually branches within the cylinder head (see Figure 2: ) 0). In front of the second intake boat 4.5, the branched intake passage 10.11 is divided into two by a partition wall 9 formed to protrude substantially along the center line in the width direction. They are connected to second intake boats 4 and 5, respectively. As shown in the figure, a shutter valve 2 is provided on the upstream side of the intake passage 8. 5
Although the second shunter valve 12 is not specifically shown, it closes the intake passage 8 during low load operation of the Ennon E by a well-known opening/closing control (a link mechanism connected to a throttle valve, for example), and closes the intake passage 8 during high load operation. Sometimes, the opening and closing of the intake passage 8 is controlled to open according to the load.
On the second flow side from the shutter valve 12, there is an intake passage 8.
With respect to the center line, the upstream opening 13a of the auxiliary intake passage 13 is opened at the bottom wall of the intake passage 8 by leaning toward the first intake boat 4 side. This auxiliary intake passage 13 is opened slightly upstream from the tip 9a of the partition wall 9 that partitions the branched intake passage 10°1, and has a downstream side D1311 serving as an intake port opening. By setting the downstream side passageway I11131) at such a position, it is possible to sufficiently ensure the width direction = J direction.
3 is gently curved so as to cross the width direction center line P mentioned in 1, and communicates between the upstream side opening 13a and the lower light side opening D 1313. That is, the passage wall 13c on the second intake boat 5 side of the auxiliary intake passage 1:(
Intake boat, towards the 1st side.

It is curved at an angle.

As shown in FIG. 2, the auxiliary intake passage 13 is formed in a bottom wall 14 forming the bottom of the intake passage 8, and its downstream opening 13b is on the downstream side of the partition wall 9. It is set slightly upstream from the end 9a, that is, the branch point of the branched intake passage 10°11. Therefore, the intake air flowing down the auxiliary intake passage 13 has an Ijf ability to be distributed to both the branch intake passages 1O, 11, or the auxiliary intake passage 13 is inclined toward the first intake boat 1 side. Because it is formed by
The intake air has a directivity toward the first intake boat 4 (1), and almost the entire amount flows from the first intake boat 1 into the combustion chamber.
A and others will be doing so. The auxiliary intake passage 13 is
The first intake boat 4 is directly connected to the branch intake passage 1 () which is curved in the axial direction of the cylinder 1, and the cylinder 70
It intersects at a slight angle of inclination to the mating surface C of Nk 31 and Schilling 7D 3 (), and therefore,
It has directionality oriented in the circumferential direction of the combustion chamber 2.

1- Slightly below the upstream side of the auxiliary intake passage 13 1-113a; a shutter valve 712 for opening and closing the intake passage is provided so as to be inclined obliquely downward toward the downstream side, and the shutter valve 12 A fuel injection valve 17 can be inserted into a hole (=1 part 16a) previously provided on the upper wall 16 of the intake passage 8 located slightly downstream. In this case, the fuel injection port 18 is
It is set to be located slightly downstream of the rotating shaft 121 of the shunter pallet 712 and on the center line of the intake passage 8.

Note that the intake valve that opens and closes the first intake boat 4] 5. The intake valve that opens and closes the second intake boat 5 (not shown) and the bleed valve 10 that opens and closes the Senki boats 6 and '7 (the number is not shown). figure)
are driven to open and close by a well-known overdrive mechanism 20 at a fixed timing I91 synchronized with the rotation of the engine E.

Further, as shown in FIG. 1, the spark plug 21 is connected to the first.
2nd intake bow) 11. ．． 5 and bleed boat.

Set it in the center of the grilling chamber 2 in the part where it is not provided, more like Hyogo style.

] - With the configuration of the auxiliary intake passage 13, the passage area of the auxiliary intake passage 13 can be made sufficiently large, so the load range that can be handled with the shutter valve 12 closed can be expanded. Moreover, since the intake air flowing down through the auxiliary intake passage 13 has directivity in the circumferential direction of the combustion chamber 2, a good whirl can be maintained within the expanded load range.

Furthermore, as the load range is expanded to the high load side, the amount of intake air when the shutter valve 12 is closed can be secured, so even if the shutter valve 12 is opened and shifted to high load operation, the shutter valve 12 Increased air intake when opened! ', i'1 can be made relatively small, thereby reliably preventing so-called cutting.

Then, the shutter valve is opened and the high load link is opened.
So, first. 2nd intake boat... Necessary intake air is supplied from 1 and 5, maintaining high output of ζ, 2 boats and 1 boat, 111
do.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of a main part of the top embodiment of the present invention, and FIG. 2 is a longitudinal cross-sectional view taken along the line II--II in FIG. 1. 2... Combustion chamber, - L, 5 1st. 2nd intake boat,...Intake passage, 9...Partition wall, H),]]...Branch intake passage, 12...Shutter valve, 13...Auxiliary intake passage, (13b... downstream side, 13c...second intake boat side passage wall), 14...bottom wall, 15...intake valve. Patent applicant: Toyo Kogyo Co., Ltd.

Claims (1)

[Claims] (1) A plurality of intake boats each opened and closed by an intake valve are opened into the combustion chamber, and are opened and closed by an on-off valve that closes at low load and opens at high load, and are branched downstream of the on-off valve, and each branch end is connected to the intake boat An intake passage connected to each port and branched from an intake passage upstream of the above-mentioned on-off valve,
An auxiliary intake passage connected to any one of the intake ports is provided, and the auxiliary intake passage has an intake boat opening upstream of the intake passage branch point, and a passage wall on the other intake boat side. An intake system for an engine, characterized in that the intake port is inclined from the other intake port toward the intake boat side where the auxiliary intake passage opens.