JPS60198330A - Intake device for engine - Google Patents

Abstract

PURPOSE:To achieve swirl of desired of desired strength under wide operational range and to improve the combustion performance by providing an auxiliary intake path branched from an intake path in the upstream of a gate valve while/ communicated to one intake port and enlarging the diameter of the intake port communicated with said path. CONSTITUTION:Plural intake ports 5, 6 are opened to a combustion chamber 4 while a gate valve 18 to be closed under low load operation is arranged in main intake path 11 communicatable through branch intake paths 15, 16 with respective intake port 5, 6. An opening 19 is formed through the bottom of main intake path 11 in the upstream of the gate valve 18 while an auxiliary intake path 20 is extended from said opening 19 to the underside of main intake path 11 and coupled through an opening 21 to first intake port 5. The diameter of the first intake port 5 is made larger than that of the second intake port 6 thereby the auxiliary intake path 20 to be coupled with the first intake port 5 is enlarged.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention comprises multiple intake boats for introducing intake air into the combustion chamber of an engine, and an intake passage connected to each intake boat. The present invention further relates to an engine intake system including an auxiliary intake passage connected to any one of the intake boats.

(Prior art) In order to increase the output of an engine, it is necessary to expand the intake passage area and improve the filling efficiency, but if one intake boat has a large passage area, For reasons such as the inertial weight of the intake valve becoming large and the follow-up performance becoming worse, and the strength of the combustion chamber structure being disadvantageous, it is recommended that the engine be designed to increase output by introducing intake air from two intake boats. Air intake structures have been known for some time.

Such a two-boat type intake system has the advantage of being able to introduce a large amount of intake air and obtain high output during high-load operation, but during low-load operation with less air intake, the intake flow rate decreases. This causes problems such as deterioration of ignitability and deterioration of combustibility.

In order to eliminate such disadvantages, it is known to improve the combustibility during low load operation by increasing the intake air flow velocity and forming an intake air swirl during low load operation. For example, Japanese Patent Application Laid-open No. 56-44419 discloses two intake ports opening into the combustion chamber and one port on these boats.
1. An intake system in which two intake passages branched from one intake passage are connected to each other, and one of the branched intake passages is provided with a shutter pulp that opens at high load. An iI construction is disclosed.

In this device, since the shutter pulp is closed during low load operation, intake air is introduced only from the other branch intake passage where the shutter pulp is not provided.

In this device, this prevents a decrease in the flow velocity of intake air and generates a swirl of intake air.

However, since this device is intended to ensure sufficient intake air charging during high-load operation, the intake passage introduces the intake air flow in the axial direction of the combustion chamber. Even if intake air is introduced from one intake port during low load, it is difficult to form a strong swirl within the combustion chamber. Also, in this disclosed device, there is no difference in the size of the two intake ports, so if the load increases.

In order to secure the amount of intake air, it is necessary to open the Shattano (Luso) relatively early and introduce intake air from the two intake ports.However, when the two intake ports are opened, the swirl-generating force of the intake air quickly weakens and combustion Therefore, this device cannot ensure good combustibility over a wide load operating range.

(Objective of the present invention) An object of the present invention is to provide an auxiliary intake passage that can form an intake swirl of desired strength and ensure good combustibility in a wide load operation range from low load to medium load. It is an object of the present invention to provide an intake system for an engine equipped with the following.

(Configuration of the present invention) In order to achieve the above object, the present invention is configured as follows. That is, the intake device of the present invention has a plurality of intake ports that open into the combustion chamber, an intake passage that communicates with the intake port, and an intake passage that is provided in the intake passage and is controlled in the closed direction during low-load operation and in the open direction during high-load operation. and an on-off valve that increases or decreases the passage area of the intake passage, and the on-off valve also includes an auxiliary intake passage that branches from the bottom of the upstream intake passage and communicates with one of the intake ports. ing.

The port diameter of the intake port with which this auxiliary intake passage communicates is larger than the port diameter of the other intake ports, so that the passage area of the auxiliary intake passage is relatively large. The auxiliary intake passage is preferably
The auxiliary intake passage branches off from a position opposite to the intake port where the passage area is smaller than the passage area of the intake passage. In an operating range where the on-off valve is closed, intake air is supplied only from the auxiliary intake passage. in this case·
Since the auxiliary intake passage opens the lower side of the branched intake passage into a 2[8] intake boat, the intake air flow is directed into the combustion chamber at a relatively shallow angle, that is, at an angle close to perpendicular to both lines of the combustion chamber. , the intake air flow is sent into the combustion chamber from only one intake port at a position that is biased to the side with respect to the axis of the combustion chamber, creating a strong swirl flow around the axis of the combustion chamber. Form.

According to the above configuration of the present invention, the diameter of the intake port with which the auxiliary intake passage communicates is larger than the diameters of the other intake ports. Therefore, the cross-sectional area of the auxiliary intake passage can be expanded without any inconvenience, so even if the amount of intake air increases as the load increases, the desired amount of intake air can be met by supplying air only from the auxiliary intake passage. . That is, a desired amount of intake air can be ensured while effectively forming a swirl only from the auxiliary intake passage over a wide load operating range. Further, by setting the opening period of the intake valve associated with the intake valve with which the auxiliary intake passage communicates to be longer than that of other intake valves, the usable area of the auxiliary intake passage can be expanded even more efficiently.

(Effects of the present invention) According to the present invention, there is provided an intake system in which both intake ports are opened in i combustion chambers to ensure a high filling amount of intake air during high-load operation. As such, a swirl of desired strength can be obtained in a wide operating range from low-load operation to medium-load operation, and therefore stable and good combustion conditions can be obtained in this wide range.

(Description of an Embodiment) Referring to FIGS. 1 and 2, an engine E has a cylinder block 1 having a cylinder diameter and a cylinder head 2 attached to the upper part of the cylinder block 1. A piston 3 is arranged so as to be able to reciprocate in the axial direction, and forms a combustion chamber 4 within the cylinder body 1a. A first and second intake boat 5.6 and an exhaust port 7 are formed in the cylinder head 2. An intake valve 8 is attached to each of the first and second intake boats 5.6Vc, and an exhaust valve 9 is attached to the exhaust port 7. It will be done. Referring to FIG. 1, the first intake boat 5 is also formed to have a larger diameter than the second intake boat, and the cylinder center in the width direction of the cylinder block 1 @
The exhaust port 7 is arranged symmetrically with respect to tVC, and the exhaust port 7 is arranged at a position facing the second intake boat 6 across the longitudinal center line m of the cylinder glock 1.

The intake system includes a main intake passage 11 extending from the air cleaner 10.
A throttle valve 12 is disposed within the main intake passage 11. Shoulder 1 As shown in Figure 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 wall formed so that the cylinder center axis tK in the width direction of the cylinder block is approximately parallel to the main intake passage 11. 14, forming first and second branch passages 15.16 which communicate with the first and second intake boats 5.6, respectively. The exhaust port 7 is connected to the exhaust passage 17 to constitute an exhaust system. This exhaust system may have a normal configuration. The main intake passage 11 has a partition wall 1
A fuel injection valve 23 is disposed upstream of the combustion chamber 4, and fuel metered based on a signal corresponding to engine operating conditions is supplied to the combustion chamber 4. An on-off valve 18 is provided in the main intake passage ll.

For example, this on-off valve 18 is linked to the throttle valve 12Vc, and is closed in a low-load operation region where the opening degree of the throttle valve is relatively small, and is opened when the throttle valve 12 is opened beyond a predetermined opening degree. It is configured as follows. An opening 19 is formed at the bottom of the main intake passage 11 slightly upstream of the on-off valve 18, and an auxiliary intake passage 2° is formed extending from this opening 19 to 11411 below the main intake passage @11. . Auxiliary intake passage 2
o has a passage approximately comparable in diameter to the first branch passage, passes from the lower side of the main intake passage 11 to the lower side of the first branch passage construction 5, and connects the first intake port 5 with the opening 21. It is connected to the. As shown in Fig. 2, the intake port 5 opens into the combustion chamber 4 at an angle close to the axial direction of the cylinder a to ensure a high filling amount during high-load operation. Although not shown, the second intake boat 6 also has a similar shape.

On the other hand, since the auxiliary intake passage 20 opens from the lower side of the main intake passage 11 and the first branch passage 15 to the first intake port h5, it is oriented at a relatively shallow angle with respect to the combustion chamber 41C. . Furthermore, since the first intake boat 5 is arranged to be biased to one side with respect to the center line t of the cylinder bore la, the intake air jetted into the combustion chamber 4 at a shallow angle from the auxiliary intake passage 2o is directed within the combustion chamber 4. Generates a strong swirl, that is, a strong swirl in the horizontal plane. In order to facilitate the generation of this swirl, the shape of the auxiliary intake passage 20 is formed so that it faces almost tangentially to the peripheral wall of the cylinder pore 1a near the opening 21. It is desirable to do so. In order to obtain such a shape, it is necessary to curve the auxiliary intake passage 20. However, as shown in FIG.
The side opposite to the first intake boat 5 with respect to the center of
Since it is placed closer to the intake boat 6, the opening 2
1, it is not necessary to give the auxiliary intake passage 20 an extreme curvature. A shape with less flow path resistance can be achieved.

In an operating region with a low relative load in which the on-off valve is closed, all the intake air passing through the main intake passage 11 is guided from the opening 18 to the auxiliary intake passage, and is sent into the combustion chamber from the opening 21 through the first intake port 5. It will be done. Since the auxiliary intake passage 20 is oriented in the circumferential direction of the cylinder ♂a 1a at a relatively shallow angle as described above, the intake air jetted from the auxiliary intake passage 20 into the combustion chamber 4 is directed into the combustion chamber 4. to form a strong swirl.

In this example, the first intake port 5 has a larger diameter than the second intake port 6, and accordingly, the auxiliary intake passage 20 connected to the first intake 4-beat 5 is also formed larger.

Therefore, even if the load increases to some extent and the amount of intake air increases, the total amount of intake air can be satisfied by the intake air sent from the auxiliary intake passage 20. Therefore, even in an operating range where the load is relatively increased, there is no need to open the on-off valve 18, and the swirl of intake air can be maintained in the combustion chamber, and good combustibility can be maintained.

Further, when the load increases and the throttle valve 12 is opened beyond a predetermined value, the on-off valve 18 also begins to open.

In an operating range where the opening degree of the on-off valve 18 is relatively small.

A portion of the intake air is still supplied through the auxiliary intake passage 20. In this state, the auxiliary intake passage 20 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 second intake port 6. Because of the position, the amount of intake air supplied to the combustion chamber 4 via the first intake port 5 is larger than the amount passing through the second intake port 6, and as a result, such a load causes a certain amount of swirl. Enlarged areas can also be formed.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of an engine intake system showing one embodiment of the present invention, and FIG. 2 is a vertical sectional view of an engine embodying the present invention. 1... Cylinder Glock, la... Cylinder Zea,
2...-cylinder head, 3... piston, 4...
Combustion chamber, 5.6...Intake port, 7...Exhaust port, 11...Main intake passage, 15.16-...Branch intake passage, 18...Opening/closing valve, 19...Opening, 20... Auxiliary intake passage. Figure 1

Claims (1)

[Claims] A plurality of intake boats that open into the combustion chamber, an intake passage that communicates with the intake port, and an intake passage that is provided in the intake passage and are controlled in the closed direction during low load operation and in the open direction during high load operation to reduce the passage area of the intake passage. In an engine intake system equipped with an on-off valve that increases or decreases, the intake passage branches from an intake passage upstream of the on-off valve and communicates with one of the intake boats, and has a passage area that is larger than the passage area of the intake passage. A small auxiliary intake passage is provided, and the passage area of the auxiliary intake passage is expanded by making the diameter of the intake boat with which the auxiliary intake passage communicates larger than that of the other intake boats. engine intake system.