JPS6093119A - Suction device of engine - Google Patents

Abstract

PURPOSE:To produce a strong swirl in a combustion chamber over a relatively wide range of a low load running area by locating the center of the opening of an auxiliary intake air path branching from a main intake air path, in a position deviating in the direction opposite to the position where the other intake air port is located, from the center of the main intake air path. CONSTITUTION:In a low load running area where a closing valve 18 is closed, all the intake air passing through a main intake air path 11 is led from an opening 19 to an auxiliary intake air path 20, and is fed to a combustion chamber 4 from an opening 21 through the first intake air port 5, thus, a strong swirl is formed. With increasing the engine load, a closing valve 18 also begins to open when a throttle valve opens beyond its specified value. In the running area where the opening of the closing valve 18 is relatively small, since the auxiliary intake air path 20 opens only the first intake air port 5 and the opening 19 is located in a position deviating toward the second intake air port 6, the quantity of intake air supplied to the combustion chamber 4 through the first intake air port 5 becomes larger than the quantity of intake air passing through the second intake air port 6. Thus, a certain degree of swirl can be formed even in the area where the load is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine intake system, especially an engine in which a plurality of intake ports are opened in one combustion chamber, and at least one of the intake ports is connected to an engine load. The present invention relates to an engine intake system of a type that is selectively used according to the type of engine.

(Prior art) Is there a plurality of intake ports in the engine combustion chamber? It is known to use them selectively depending on the engine load. For example, Tokukai Showa S Otsu-4tlI4! ,
In the engine disclosed in the ity publication, a branch intake passage is connected to each of the warm air νJ9-to of the coil 1^1 formed in the cylinder head, and this branch intake passage is connected to a common main intake) I! It is connected to I.

One of the branch intake passages is provided with an on-off valve, and the main intake passage is provided with a throttle valve.The throttle valve and the on-off valve work together to control the opening of the throttle valve at once. The open IJ valve opens when it is opened beyond f'1. It has become so.

In other words, since the force branches 0 & 1 are controlled by on-off valves when the engine is operating at low load, intake air is supplied at a relatively high flow rate only from the other branch 1 air passage. During operation with one acid load, intake air is not supplied from both branch intake passages to ensure a high filling amount.

However, since the engine intake system described in this publication is intended to ensure sufficient intake air filling during high-load operation, the cross-sectional area of each branch intake passage is not very small. Even if only one branch intake passage is used during low-load operation, the intake flow velocity can be sufficiently increased in operating ranges where the load is very small, such as during idling.

The expansion and softening of the neck hole and intake date allows the intake air flow to be introduced almost along the axis of the combustion bank in order to ensure a high filling amount during high-load operation. Coupled with the fact that the cross section of the branched intake passage cannot be made very small, this makes it difficult to form a strong swirl within the combustion chamber during low load operation.

Unexamined Japanese Patent Publication No. 1973-. 23! f; / Publication No. 7 discloses that in an engine intake system having 7 intake ports, each intake port is opened with a small auxiliary intake passage with a cross section of i\1'I, and this auxiliary intake passage is used during low-load operation. A technique is disclosed in which a narrow high-speed intake air flow is blown from an intake passage. The engine intake system described in this publication uses the high-speed intake air that blows into the combustion chamber during low-load operation to form intense turbulence near the center of the combustion chamber and near the ignition plug. The aim is to promote stable combustion by promoting scavenging and increasing the flame propagation speed. However, in this intake system, the auxiliary intake passage exerts its full effect during operating conditions where the engine load is very low, such as idling, but in operating areas where the engine load increases even slightly, the auxiliary intake passage alone is insufficient. Since it is not possible to secure a sufficient amount of intake air, it becomes necessary to open a branch intake passage that is continuous with each intake port. When the branch intake oil passage is opened even slightly in this manner, the flow velocity of the intake air flow from the auxiliary intake passage decreases rapidly, and the turbulent flow within the combustion chamber is weakened. Therefore, this intake system cannot provide a satisfactorily stable combustion condition over a range from a region where the engine load is slightly above the idle state to a medium load region.

(Objective of the Invention) The present invention provides an intake system that can omit opening a plurality of intake ports in one combustion chamber to ensure high intake air filling during high-load operation, over a relatively wide range of low-load operation. The overall purpose is to form a strong swirl in the combustion chamber over a period of time, thereby making it possible to obtain good combustion conditions.

(Structure of the Invention) In order to achieve the above object, the present invention has the following structure 11+2. That is, the engine intake device according to the present invention has the following features:
@Ki of the number of sheets opening into the combustion chamber? - a branch intake passage connected to each of the four intake ports, a main intake passage connected to the upstream side 1 of the branch intake passage, and a main intake passage provided in the main intake iJJ passage for high-load operation. an on-off valve that opens when the on-off valve opens, and an auxiliary intake passage that branches from the main intake passage and connects to one of the intake ports through an opening provided at the bottom of the main intake passage upstream of the on-off valve; The center of the opening where the auxiliary leg passage branches from the main intake passage is located opposite to the one intake port (ill) with respect to the center of the main intake passage. According to this configuration of the present invention, in the low-load operation region where the on-off valve is closed, intake air is supplied only from the auxiliary intake passage. Since the entire intake port opens, the airflow is directed into the combustion chamber at a relatively shallow angle, that is, at an angle close to an angle with respect to the axis of the combustion chamber, and the intake airflow is directed toward the combustion chamber from only one intake port. Since it is not fed into the combustion chamber at a position that is deviated to the side with respect to the axis of the chamber, a strong turning flow, or swirl, is formed relative to the axis g of the combustion chamber.

The aforementioned Akira Uekai, t,! ;-,23! / The intake system described in Publication No. 7 has a configuration that generates swirl in the combustion chamber, and strong turbulence occurs along the solid wall of the combustion chamber, and is less likely to occur near the center, so the ignition plug is placed in the center. Based on the recognition that it is not possible to maintain good combustion in the engine that was used in the vicinity, small-diameter auxiliary intake passages were opened in each of the intake ports of the a-ga, and from these auxiliary intake passages a thin By blowing a high-speed flow symmetrically into the combustion chamber, the aim is to create severe turbulence around the center of the combustion chamber. The present invention uses such a known intake system U, which is relatively small. A strong swirl is generated within the combustion chamber by blowing the high-speed intake air into the combustion chamber in a direction that is biased against the fine details of the entire combustion chamber. In particular, in the present invention, the opening of the portion where the auxiliary intake port branches from the main intake passage is self-aligned with its center offset from the center of the main intake passage,
The direction of the bias is opposite to the direction of bias of the intake mortar to which the auxiliary intake passage is connected. Therefore, even if the intake flow from the auxiliary intake 1ffJ passage is formed toward the circumferential direction of the combustion chamber to increase the tendency for swirl to occur, there is no need to apply extreme opening force to the auxiliary intake passage. It becomes possible to form an auxiliary intake passage with low intake resistance.

(Effects of the Invention) According to the present invention, since the auxiliary intake passage used in the low-load operation region is branched from the bottom of the intake passage,
The auxiliary intake passage follows the lower side of the main [F] air passage and the auxiliary +4 evening air passage and opens into the intake port, and since this auxiliary intake passage is connected to one intake port, the low Load: Even with a relatively small amount of air pressure during IW rotation, a strong swirl can be formed in the combustion chamber, ensuring combustion stability. Furthermore, the center of the opening at the part where the auxiliary intake passage branches from the main intake passage is biased toward the center of the main +9j air passage and the opposite side of the intake port to which the auxiliary intake passage is connected. Therefore, even if the direction of the connection between the auxiliary intake passage and the first air port is oriented toward the circumferential direction of the combustion chamber to facilitate formation of swirl, it is not necessary to apply extreme bending force to the auxiliary intake passage. 1h (It is possible to form an ideal auxiliary intake passage with small interest payments.As the auxiliary intake passage branches off from the main intake passage at a biased point W as described above, the opening/closing valve In the load range where the intake airflow starts to open, the amount of intake airflow ωr that all four intake boats curve becomes uneven, and as a result, it can be expected that a certain amount of swirl will occur.

(*Explanation of example) Referring to Figure 7 and Figure 2, engine E has cylinders 718? A cylinder block l having a cylinder block 1 and a cylinder head 2 added to the upper part of the cylinder block 1 have been completely repaired, and a piston 8 is disposed in the cylinder bore 1a so as to be able to move freely in the axial direction, and a combustion chamber 4 is formed in the cylinder bore 1a. ．． 't
thff. The cylinder head 2 has first and second intake Ft? -)5. (S and exhaust port 7 form six, mud 1
1. The second intake port 5.6 has a nascent valve 8, respectively, and the exhaust yJ? - An exhaust valve 9 is attached to the door. Referring to FIG. 1, the seventh and second intake ports 5 and 6 have approximately the same diameter and are arranged approximately symmetrically with respect to the cylinder center line in the width direction of the cylinder block l, and the exhaust port 7 is located along the longitudinal axis of the cylinder block l. Staring 2 intake boat 6 with direction center line m
It is placed in a position facing the

The intake system includes a main intake passage 11 leading from the air cleaner lO.
A throttle valve 12 is disposed within the main intake passage 11. As shown in FIG. 1, the main intake passage 11 extends into the cylinder head 2, and is formed in the vicinity of the intake port 5.6 by a partition formed substantially along the cylinder center line l with the same cylinder block width. A first intake boat 5.6 is separated by a wall 14 and opens into a second intake boat 5.6, respectively. There are 15.16 second branch passages. The exhaust port 7 is connected to the exhaust narrow passage 17 to constitute an exhaust system. This exhaust system F
iA normal configuration is sufficient. The main intake passage 11 has a partition wall 14
A fuel injection valve 28 is arranged on the mud side of the engine, and the engine operation φ
The fuel metered based on the signal corresponding to the
can be supplied to. An on-off valve 18 serves within the main intake passage 11.

This opening valve 18 is, for example, a throttle valve 12. In connection with F11, the throttle valve is closed in a low load operating range where the opening degree is relatively small, and is configured to be opened when the throttle valve 12 is opened more than a predetermined number of times. An opening 19 is formed at the bottom of the main intake passage 11 on the #L side slightly above the on-off valve 18.
An auxiliary intake mountain passage 20 is formed to extend below the main intake passage 11 from the opening 19. Auxiliary intake passage 2
0 passes under the main intake passage 11 (from the jull) below the first branch passage J5 and is connected to the first intake port 5 through the opening 21. As shown in FIG. In order to preserve the high light filling amount when the high 9 load is applied, the cylinder pore 1a17) IlIIl! Combustion phosphorus ♀4 at the corner 1t close to the direction of burning
Although not shown in the figure, the third intake port 6 also has a shape similar to that of the first. In contrast, since the auxiliary intake passage 2 (1 is open to the first intake port 5 from the lower side of the main intake passage 11 and the first branch passage 15), the combustion chamber 4
4, it will be pulled at a relatively shallow angle. Furthermore, the five intake ports are arranged biased to one side with respect to the center line J of the cylinder pore la, so that the intake air flowing from the auxiliary intake passage 20 into the combustion chamber Φ at a shallow angle is directed into the combustion chamber 4. , a strong swirling flow in the horizontal plane, ie, a swirl, occurs.

In order to facilitate the generation of this swirl, it is desirable that the shape of the sleeve assisting air passage 20 be formed in the vicinity of the opening 21 in substantially the same way as the circumferential wall of the cylinder pore la in the connecting direction. In order to obtain such a shape, it is necessary to curve the auxiliary intake passage 2(). However, as shown in FIG.
The opening 19 of the part branching from the main intake passage 11 is located on the side opposite to the first intake port 5 with respect to the center of the main intake passage 11; Therefore, even if the shape is shaped along the circumferential direction of the cylinder pore 1a in the vicinity of the opening 2, there is no need to give the auxiliary intake passage 20 an extreme bend, and as shown in FIG. The shape can be a gentle flow path with low resistance.

In the low-load region where the on-off valve 18 is closed, all the intake air passing through the main intake channel 11 is guided from the opening 18 to the auxiliary 11 and the air passage 20, and is sent from the opening 21 to the combustion chamber via the first intake port 5. Includes 1. Kamisuke 1 Shioki passage 20 branches branch passage 1
Since the cross-sectional area is smaller than those of Nos. 5 and 16, a relatively high flow rate can be maintained even during low-load operation with a small intake brass. Furthermore, the auxiliary intake ilQ passage 20 is 81 [as described above, directed at a relatively shallow angle in the circumferential direction of the cylinder pore
4 V from the auxiliary intake passage 20 to the combustion chamber.
The warm air flowing out of the CC forms a strong swirl within the combustion chamber 4. As shown in FIG. 1, in this embodiment, the cylinder head 2 has intake and exhaust air. - The part where the cylinder block J is not formed into a J shape, i.e. the center line m in the longitudinal direction of the cylinder block J.
An ignition plug 22 is attached to a portion facing the intake boat 5, sandwiching the l)4/ intake boat 5. Therefore, the ignition plug 22 is
Since it is located on the swirl trajectory formed by the intake air flow from the auxiliary intake passage 20, fresh air-fuel mixture is reliably supplied to the vicinity of the ignition plug 22, and combustion is performed with good ignitability.

When the throttle valve 12 is opened beyond the PJrw value as the engine load increases, the on-off valve 18 also begins to open.

Once or in a relatively small operating range of the switching valve 18, a portion of the intake air is still supplied along the auxiliary intake channel 2(). In this state, the auxiliary intake passage 2° opens only to the first intake port 5, and the opening 19 where the auxiliary intake passage 20 branches from the main intake passage 11 is biased toward the first intake port 6. Since the first intake port 5 is located at
After that, the amount of intake air supplied to the combustion chamber Φ becomes larger than the amount passing through the second air boat 6, and as a result, the V
A swirl can be formed even in areas with heavy loads.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of an engine intake system showing an embodiment of the present invention, and FIG. 1 is a vertical sectional view of an engine embodying the present invention. J,... Cylinder block, 1a... Cylinder pore, 2... Cylinder head, 8... Piston, 4...
・Combustion chamber, 5.6...Intake z-1, ? ...Exhaust--
G, 11... Main@Normal passage, 15, lfl... Branch intake ]Ff] passage, 18... Opening/closing valve, 19... Opening, 2
0... Auxiliary intake passage. For procedural amendment 59.10.18 Showa year, month, day 1, Indication of case 1988 Patent Application No. 2020/15 2, Title of invention Engine intake device 3, Person making the amendment Relationship to the case Applicant 4, Agent 6, subject of amendment: Claims in the specification: Claim 1: A plurality of intake ports opening into a combustion chamber, a branch intake passage connected to each of the plurality of intake ports, and a branch intake passage connected to each of the plurality of intake ports; A main intake passage connected to the downstream side of the intake passage, an on-off valve provided in the main intake passage that opens during high-load operation, and an opening provided in the main intake passage upstream of the on-off valve. an auxiliary intake passage that branches from the main intake passage and is connected to one of the intake ports, and the opening where the auxiliary intake passage branches from the main intake passage has its center relative to the center of the main intake passage. An intake device for an engine, characterized in that it is disposed biased toward a side opposite to the side where the one intake port is located.

Claims (1)

[Claims] a plurality of intake ports opening into the combustion chamber; a branch intake passage connected to each of the intake ports; a main intake passage connected upstream (ill) of the branch intake passage; An on-off valve provided in the passage and opened during high-load operation, and an opening provided at the bottom of the main intake passage on the upstream side of the on-off valve, branching from the main intake passage and connecting to one of the two intake passages. The opening from which the auxiliary intake passage branches from the main intake passage has its center located at 81. An engine intake system characterized by uneven placement.