JP2003301723A - Intake air device of spark ignition engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively increase a flow speed of intake air at low speed operation time of an engine, and to effectively reduce flow resistance of the intake air at high speed operation time. <P>SOLUTION: This intake device has an intake port 7 having the downstream end opening in a combustion chamber, an intake valve 9 arranged in a throat part 73 of this intake port 7, and a shutter valve 17 for deflecting a flow of the intake air by blocking up a part of a peripheral part of the intake port 7 in a low speed area of an engine. A cross-sectional shape of the intake port 7 positioned on the upstream side of the throat part 63 is formed so as to become relatively smaller than the other in the opening area of an opening part positioned in either one of the upper wall 7a side or the lower wall 7b side more than the vertical center line of the opening part. The opening part having the small opening area is formed in an eccentric shape of positioning the passage center on the outer side more than a gravity center position of the whole opening part of the intake port 7. The shutter valve 17 is arranged on the opening part side having the large opening area, and is constituted so as to open-close this part. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake port whose downstream end opens into a combustion chamber, an intake valve which opens and closes this intake port, and a part of the peripheral portion of the intake port which is closed in a low engine speed region. The present invention relates to an intake device for a spark ignition type engine having a shutter valve that deflects the flow of intake air.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Unexamined Patent Publication No. 2001-173.
As disclosed in Japanese Patent No. 513, a throttle portion that reduces the opening area of the downstream side portion of the intake port as compared with the upstream side portion is provided, and a tumble flow is generated by the intake flow introduced into the combustion chamber. In an intake system for an engine, by tilting the central axis of the inner peripheral surface of the valve seat mounted at the inlet of the combustion chamber of the intake port with respect to the central axis of the outer peripheral surface along the flow path of the intake port, The intake flow supplied through the intake port is smoothly introduced into the combustion chamber along the guide surface of the valve seat.

[0003]

When the throttle portion for reducing the opening area of the downstream side portion of the intake port as compared with the upstream side portion is provided as described above, the throttle portion is provided in the throttle portion during low speed operation of the engine. Since the flow velocity of intake air can be increased, there is an advantage that the combustibility can be improved by strengthening the tumble flow generated in the combustion chamber and promoting stratification of the air-fuel mixture. On the other hand, since the ventilation resistance of the intake air in the throttle portion is large, there is a problem that the intake air amount is insufficient and the combustibility is easily deteriorated at the time of high-speed operation of the engine in which the required intake air amount and the fuel injection amount are large.

In order to increase the strength of the tumble flow during low speed operation of the engine and to supply a large amount of intake air into the combustion chamber during high speed operation, it is disclosed in, for example, Japanese Patent Laid-Open No. 2001-55925. As described above, a partition wall that divides the intake port into an upper port portion and a lower port portion and a tumble control valve that adjusts the tumble flow generated in the combustion chamber are provided. By closing the lower port with a control valve, etc., to speed up the flow rate of intake air and increase the strength of the tumble flow, and during uniform combustion operation with a high engine speed, hold the tumble control valve in the neutral position. , The ventilation resistance of intake air is made as small as possible.

However, even if the tumble control valve is held in the neutral position during high speed operation of the engine as described above,
There is a problem in that it is difficult to secure a sufficient intake amount because the flow of intake air is blocked by the partition wall having a predetermined length.

The present invention has been made in view of the above points, and it is possible to effectively increase the flow velocity of intake air during low-speed operation of the engine and effectively reduce the ventilation resistance of intake air during high-speed operation. It is an object of the present invention to provide a spark ignition type engine intake device that can be used.

[0007]

The invention according to claim 1 is
An intake port whose downstream end opens into the combustion chamber, an intake valve that opens and closes this intake port, and a shutter valve that deflects the flow of intake air by closing a part of the periphery of the intake port in the low engine speed region. In the spark ignition engine, the upper wall of the intake port, which is located closer to the center of the combustion chamber, is provided so that a part of the valve guide wall that supports the intake valve projects into the intake port. The cross-sectional shape of the intake port located on the upstream side relative to the vertical centerline of the opening is such that the opening area of the opening located on either the upper wall side or the lower wall side is relatively larger than the other. An opening with a small opening area and an eccentric shape whose center of passage is located on the outer side of the center of gravity of the entire opening of the intake port and with a large opening area By disposing the shutter valve, which is constituted to open and close the part.

According to the above construction, when the engine is in the operating region of high rotation, the shutter valve is opened, so that a large amount of intake air smoothly flows into the combustion chamber and the engine rotates at low rotation speed. When in the driving range of
By closing the shutter valve, the flow of intake air is deflected to either the upper wall side or the lower wall side to accelerate the flow velocity of the intake air and to be guided to the passage center side. As a result, swirling along the inner surface of the side wall portion from either one of the upper wall side or the lower wall side, the intake air flows into the combustion chamber while bypassing the installation portion of the intake valve, and a proper tumble flow is generated. It will be.

According to a second aspect of the present invention, in the spark ignition engine intake system according to the first aspect, when viewed from a direction orthogonal to a longitudinal section of the intake port along the cylinder axis, the valve guide installation portion is upstream. The axial line of the intake port located on the lower side is formed substantially straight, and the opening area of the lower wall side opening located on the outer peripheral side of the combustion chamber of the intake port is the upper wall side opening located on the combustion chamber center side. The cross section of the intake port is formed to be relatively smaller than the above.

According to the above construction, the intake air smoothly flows along the axis of the intake port, and when the engine is in the low speed operation region, the intake flow deflected to the lower wall side by the shutter valve is generated. By being guided to the center of the passage, the intake air swirls along the inner surface of the side wall portion from the lower wall side, bypasses the installation portion of the intake valve, and flows into the combustion chamber.

According to a third aspect of the present invention, in the intake system for a spark ignition type engine according to the second aspect, there is provided a pair of intake ports having a downstream end opening into the combustion chamber, and the combustion chamber outer peripheral side between the intake ports. In addition to the injector, a spark plug is placed on the center side of the combustion chamber between both intake ports, and the opening on the lower wall side of the intake port is located at the center of gravity of the entire opening of the intake port. Also has an eccentric shape located on the opposite side of the adjacent intake port.

According to the above structure, the injector is effectively utilized by utilizing the space formed on the lower wall side between the intake ports while preventing the injector from interfering with the installation portion of the spark plug and the intake valve. It becomes possible to dispose at an appropriate position.

According to a fourth aspect of the present invention, in the spark ignition engine intake system according to the third aspect, the opening on the upper wall side of the intake port is formed into a substantially rectangular shape.
The opening on the lower wall side is formed in a substantially triangular shape with a downward constriction.

According to the above construction, a space for arranging the injector is formed on the lower wall side between the intake ports, and when the engine is in the low rotation speed operating region, the upper part formed in a substantially rectangular shape is formed. By closing the opening on the wall side by the shutter valve, the flow of intake air is deflected to the opening on the lower wall side formed in a substantially triangular shape, and then while the intake air is swirling along the inner surface of the side wall, It bypasses the installation part of the intake valve and flows into the combustion chamber.

The invention according to claim 5 is the above-mentioned claims 1 to 4.
The spark-ignition engine intake device according to any one of claims 1 to 5, further comprising a pair of intake ports having a downstream end opening into the combustion chamber, and a common portion branched from a single intake passage toward the pair of intake ports. At the same time, when viewed from a direction orthogonal to the longitudinal section of the intake port along the cylinder axis, the intake port from the installation portion of the valve guide to the common portion is formed in a substantially straight shape.

According to the above construction, the intake air smoothly flows from the common portion through the intake port, and when the engine is in a low rotation operating region, the intake flow deflected to the lower wall side by the shutter valve. Is guided to the passage center side of the opening portion on the lower wall side, so that the intake air swirls along the inner surface of the side wall portion from the lower wall side and bypasses the installation portion of the intake valve and flows into the combustion chamber. It will be.

According to a sixth aspect of the invention, in the intake system for a spark ignition type engine according to the fifth aspect, the shutter valve installation portion and the common portion are provided in the intake manifold, and the intake port is longitudinally cut along the cylinder axis. The intake manifold and the intake port formed in the cylinder head are connected in a substantially straight shape when viewed in a direction orthogonal to the plane.

According to the above construction, when the engine is in the low rotation speed operation region, the intake manifold provided with the common portion and the like can be effectively used to increase the flow velocity of the intake air, and The turning can be effectively promoted.

According to a seventh aspect of the present invention, in the spark ignition engine intake device according to any one of the second to sixth aspects, a pair of intake ports having a downstream end opening into the combustion chamber,
A common portion branched from a single intake passage toward the pair of intake ports is provided, and a shutter valve is provided at a downstream end portion of the common portion, and a portion directly upstream of the throat portion to the common portion. The opening portion of the intake passage on the upper wall side is formed in a substantially rectangular shape, and the opening portion on the lower wall side is formed in a substantially triangular shape with a downward constriction.

According to the above construction, the swirling of the intake flow is effectively promoted in accordance with the outward vector generated when the intake flow reaches the common portion from the single intake passage.

[0021]

1 and 2 show an embodiment of an intake system for an engine according to the present invention. In these figures, reference numeral 1 denotes an engine main body which is composed of a cylinder block 2, a cylinder head 3 and the like and has a plurality of cylinders. A piston 4 is fitted into each cylinder of the engine body 1, and a combustion chamber 5 is formed between the top surface of the piston 4 and the lower surface of the cylinder head 3. A cavity 6 is provided on the top surface of the piston 4.

The cylinder head 3 is formed with two intake ports 7 and 7 opening to the combustion chamber 5 and two exhaust ports 8 and 8 facing each other, and both intake ports 7 and 7 are provided. In addition, intake valves 9 and 9 and exhaust valves 10 and 10 for opening and closing the exhaust ports 8 and 8, an ignition plug 11, and an injector 12 are provided. The injector 12 is arranged at the peripheral portion of the combustion chamber 5, and is configured to directly inject fuel into the combustion chamber 5 from this position. Further, the spark plug 11 is arranged between the intake ports 7 and 7 on the center side of the combustion chamber, that is, on a substantially central portion of the upper surface of the combustion chamber 5.

The intake ports 7 and 7 are formed independently of each other, and as shown in FIG. 3, when viewed from a direction orthogonal to the vertical cross section of the intake port 7, that is, the cylinder axis 2A extending in the vertical direction. When viewed from a direction orthogonal to the longitudinal cross section of the intake port 7, the upstream side is the cylinder head 3
Is formed on the upper side of the combustion chamber 5, and the downstream side thereof is formed to extend obliquely downward toward the combustion chamber 5, and the downstream ends of the intake ports 7, 7 are open to the ceiling portion of the combustion chamber 5.

The intake port 7 is provided with a valve shaft 9 of an intake valve 9.
A part (lower end) of the valve guide 13 that slidably supports a is provided so as to project to a predetermined position of the upper wall 7a located on the center side of the combustion chamber 5. Further, in the above vertical cross section, the intake port 7 is
The upstream side 71 and the downstream side 72 of the installation part of the
A throat portion 73 is provided at the most downstream portion of the intake port 7, that is, at a portion immediately upstream of the valve seat 14 while being divided into the areas. On the upstream side 71 of the intake port 7, a guide wall 13a is formed on the upper wall 7a, the projection amount of which gradually increases toward the installation portion of the valve guide 13.

At least the upstream side portion 7 of the intake port 7
The axis 7A in 1 is formed in a substantially straight shape. The inclination angle of the upper wall 7a of the intake port 7 with respect to the cylinder axis 2A of the downstream side portion 72 of the valve guide installation portion is the largest in the upstream portion 72a of the downstream side portion 72 (sleeping), and this upstream portion It is formed so as to gradually decrease (stand) from 72a toward the throat portion 73 on the downstream side, and the inclination angle of the downstream side portion 72 with respect to the cylinder axis 2A is the same as that of the upstream side 71 of the valve guide installation portion. The upstream portion 72a is large with respect to the inclination angle,
It is smaller in the downstream portion 72b near the throat portion 73.

The lower wall 7b of the intake port 7 is
Cylinder axis 2A on the upstream side 71 of the valve guide installation part
Is formed in a substantially straight shape so that the inclination angle with respect to the downstream side portion 72 is larger than that of the downstream side portion 72, and a corner portion is formed at a connection portion between the downstream side portion 72 and the throat portion 73 in the lower wall 7b. 74 are formed. Furthermore, the inclination angle of the lower wall 7b in the downstream side portion 72 of the valve guide installation portion is such that the intersection P between the extension line 72B and the bottom surface of the umbrella portion of the intake valve 9 in the maximum lift state (maximum open state) is It is set so as to be located closer to the center side (exhaust port 8 side) of the combustion chamber 5 than the axis 9A of the valve 9.

Further, a cross section of the intake port 7 located upstream of the throat portion 73 (the axis 7 of the intake port 7 is shown.
As shown in FIGS. 4 (a) and 4 (b), the shape of the cross section orthogonal to A is lower wall 7b than the vertical center line (horizontal line passing through the center of the maximum vertical width) C of the horizontal cross section. Side opening area is smaller than the opening area on the upper wall 7a side, and the passage center (center of gravity of the lower wall side opening) Ob of the opening located on the lower wall 7b side has a center of gravity O of the entire opening. It is formed so as to be located on the outer side, that is, on the side opposite to the installation portion of the adjacent intake port 7.

Specifically, the opening on the upper wall 7a side of the vertical centerline C is formed in a substantially rectangular shape, and the opening on the lower wall 7b side of the vertical centerline C is substantially narrowed. By being formed in a triangular shape, the opening area on the lower wall 7b side with respect to the vertical center line C of the cross section is configured to be smaller than the opening area on the upper wall 7a side. Also,
The opening located on the lower wall 7b side is formed by forming the opening on the lower wall 7b side of the vertical center line C into a substantially right-angled triangular shape with the side portion on the adjacent intake port 7 side as the hypotenuse. The passage center Ob is formed in an eccentric shape located on the opposite side to the installation portion of the adjoining intake port 7, so that the intake port 7 has a substantially pentagonal cross-sectional shape.

Further, the axial area of the intake valve 9 is subtracted from the effective passage area of the intake port 7 shown in FIG. 4A, that is, the passage opening area of the intake port 7 at the downstream side 72 of the installation portion of the valve guide 13. The intake port 7 is formed such that the area of the intake port 7 is larger than the effective passage area of the intake port 7 shown in FIG. 4B, that is, the area of the opening of the intake port 7 on the upstream side 71 of the installation portion of the valve guide 13. Has been done.

The state of change of the effective passage area is shown in FIG. 5, and the effective passage area of the intake port 7 is from the upstream side of the intake port 7 to the starting end portion α of the guide wall 13a. It is formed to be substantially constant (in the illustrated example, it is formed to decrease slightly toward the downstream side). Further, between the starting end portion α of the guide wall 13a and the terminating end portion (the installation portion of the valve guide 13) β, the effective passage area gradually decreases toward the downstream side, and the installation portion (β) of the valve guide 13 is formed. The effective passage area on the downstream side is larger than that on the upstream side.

A mounting hole for an injector 12 extending obliquely downward in the combustion chamber 5 is formed on the outer peripheral side of the combustion chamber between the intake ports 7 and 7, and the injector 12 mounted in this mounting hole is slanted from the injector 12. In the downward direction, that is, during the stratified charge combustion operation of the engine described later, as shown in FIG.
The fuel is injected toward the tumble flow T generated in the combustion chamber 5.

An intake manifold 15 is connected to one side of the engine body 1, and the intake manifold 15 is connected to the intake manifold 15.
As shown in FIG. 2, a single intake passage 15 is provided downstream of
A common part 16 is provided to branch a toward the both intake ports 7, 7. Further, as shown in FIG. 3, the intake manifold 15 and the intake port 7 are connected in a substantially straight shape when viewed from a direction orthogonal to a longitudinal section of the intake port 7 along the cylinder axis 2A.

When viewed from a direction orthogonal to the longitudinal section of the intake port 7 along the cylinder axis 2A, the axis 7A is substantially at least from the installation portion of the valve guide 13 of the intake port 7 to the common portion 16. It is formed in a straight shape (see FIG. 3). Further, the common part 16
7 has a substantially rectangular cross-sectional shape, the opening on the upper wall 16a side is formed in a substantially rectangular shape, and the opening on the lower wall 16b side is tapered as shown in FIG. By being formed in a substantially triangular shape, the opening area on the lower wall 16b side with respect to the vertical center line of the cross section is configured to be smaller than the opening area on the upper wall 16a side.

At the downstream end of the common portion 16, that is, immediately upstream of the intake port 7 formed in the cylinder head 3, there is provided a shutter valve 17 for deflecting the flow of intake air toward the lower wall 16a of the opening passage. Has been. As shown in FIG. 7A, the shutter valve 17 is installed so that the opening on the upper wall 16a side of the common portion 16 can be closed and corresponds to the opening on the lower wall 16b side of the common portion 16. Has a notch.

The shutter valve 16, the intake manifold 15, and the intake port 7 constitute a tumble strength adjusting means for generating the tumble flow T in the combustion chamber 5 and adjusting the strength thereof. In particular,
When the drive shaft 17a of the shutter valve 17 is rotationally driven by an actuator (not shown) to close the opening on the upper wall 16a side of the common portion 16 with the shutter valve 17, the effective passage area is narrowed and the flow velocity of the intake air is reduced. By increasing the speed, the strength of the tumble flow T generated in the combustion chamber 5 is increased. Further, as shown in FIG. 7B, when the shutter valve 17 is moved to the open state to increase the effective passage area of the common portion 16, the flow velocity of the intake air becomes slow, so that the strength of the tumble flow T is increased. It is being weakened.

The fuel injection amount from the injector 12 is controlled by an ECU (engine control unit) (not shown) according to the operating state of the engine. That is,
The fuel injection amount is controlled according to the engine load, the engine speed, and the like, and the compression stroke injection is performed to inject the fuel in the compression stroke in order to distribute the air-fuel mixture around the spark plug 11 in a stratified combustion state. The fuel injection mode of the injector 12 is changed to the intake stroke injection in which the fuel is injected in the intake stroke in order to diffuse the air-fuel mixture into the entire chamber 5 and make a uniform combustion state. Further, the intake air amount adjusting means such as the shutter valve 16 and an electric throttle (a throttle valve operated by an electric actuator) (not shown) are controlled by the ECU according to an operating state.

FIG. 8 shows a control map of the fuel injection mode and the air-fuel ratio set with the horizontal axis representing the engine speed Ne and the vertical axis representing the average effective pressure Pe corresponding to the engine load. In this figure, a region below a predetermined load and below a predetermined rotational speed is defined as a stratified combustion region S, in which compression stroke injection is performed and the air-fuel ratio is, for example, A / F.
= About 40, which is significantly leaner than the theoretical air-fuel ratio. On the other hand, a region extending from the higher load side than the predetermined load and the higher rotation side than the predetermined rotation speed is defined as the uniform combustion region K,
The intake stroke injection is performed in this region K, and the air-fuel ratio is set to a substantially stoichiometric air-fuel ratio or thereby rich (λ ≦ 1), for example, A / F = 13 to 14.7.

In the uniform combustion region K, the shutter valve 17 is fully opened in order to reduce the ventilation resistance of intake air, and in the stratified combustion region S, the shutter valve 17 is opened as the engine load and the engine speed decrease. The flow of intake air is changed to the closed state, and the flow of intake air is reduced to the lower wall 7b
By deflecting to the side, control is executed to gradually increase the flow velocity of intake air and increase the tumble strength.

In the above-described structure, in the stratified charge combustion region S on the low load and low rotation side, the fuel is injected in the compression stroke from the injector 12 arranged at the periphery of the combustion chamber 5, and the air-fuel mixture is generated around the spark plug 11. By stratifying so as to be unevenly distributed, it is possible to ignite and burn with a significantly lean air-fuel ratio. Further, in the uniform combustion region K on the high load and high rotation side, the fuel is injected in the intake stroke and the air-fuel mixture is diffused throughout the combustion chamber 5, so that the air-fuel ratio becomes substantially stoichiometric or slightly rich. Ignition and combustion of the air-fuel mixture will be performed with the value set.

As described above, the fuel injection form and the air-fuel ratio can be changed according to the operating condition of the engine. Correspondingly, in the stratified combustion region S, the lower the engine speed is,
By driving the shutter valve 17 in the closing direction,
The strength of the tumble flow T will be increased. Therefore, as shown in FIG. 6, in a state where the energy of the fuel spray Fa injected from the injector 12 and the energy of the tumble flow T are properly balanced, they collide in the combustion chamber 5 and atomize the fuel. Is promoted and the fuel spray Fa is decelerated by the tumble flow T and is mixed with air, and this air-fuel mixture is wound up upward and drifts around the spark plug 11. The air-fuel mixture will be appropriately stratified around it.

As described above, the opening on the upper wall 7a side of the vertical centerline C of the cross section of the intake port 7 is formed in a substantially rectangular shape, and the opening on the lower wall 7b side of the vertical centerline C is formed. Since the opening area of the opening portion on the lower wall side 7b side is formed to be relatively smaller than that on the upper wall 7b side by forming the lower constriction into a substantially triangular shape, a stratified charge combustion operation with low load and low rotation is performed. At this time, by closing the shutter valve 17 and deflecting the intake air flow N toward the lower wall 7b side, the intake air flow N can be concentrated in the opening portion on the lower wall side and the flow speed can be effectively increased. Therefore, the combustion chamber 5
It is possible to effectively increase the strength of the tumble flow T generated in the inside, and to prevent the tumble flow T from disappearing early so that the tumble flow T can remain until the latter half of the compression stroke. It is possible to promote stratification of the air-fuel mixture and effectively improve combustion stability.

The center of the passage (the center of gravity of the lower wall side opening) Ob of the opening portion of the intake port 7 on the side of the lower wall 7b whose opening area is smaller than the position of the center of gravity O of the entire opening portion of the intake port 7 is located. Also, since the shutter valve 17 is arranged on the opening side (upper wall 7a side) having an eccentric shape located on the outer side and having a large opening area, the shutter valve 17 is configured to open and close. 2 is deflected toward the lower wall 7b side and, at the same time, the main flow of the intake flow N is guided to the passage center Ob side, so that the intake flow N is changed as shown in FIG. A vector N1 that displaces outward is generated. Then, as shown in FIG. 9, while the intake flow N swirls along the inner surface of the side wall portion from the lower wall 7b side in accordance with the vector N1, the main flow (N2) of the intake flow N is the installation portion of the intake valve 9. Will be bypassed and will flow into the combustion chamber 5. Therefore, during the stratified combustion operation of the engine, it is prevented that the flow velocity of the intake air is weakened due to the collision of the intake air flow N with the valve shaft of the intake valve 9, the spark plug 11, etc. Tumble style T
Will be generated.

On the other hand, in the uniform combustion region K of high load and high rotation, the shutter valve 17 is opened, so that the ventilation resistance of the intake air in the intake port 7 is suppressed to a small value to allow the intake air to flow smoothly. Therefore, it is possible to secure a sufficient amount of intake air introduced into the combustion chamber 5.

Further, in the above embodiment, the cylinder axis 2
The axial line 7A of the intake port 7 in the upstream side portion 71 of the installation portion of the valve guide 13 is formed in a substantially straight shape as viewed from a direction orthogonal to the vertical cross section of the intake port 7 along B. Since the cross-sectional shape of the intake port 7 is formed so that the opening area of the opening on the lower wall 7b side located on the outer peripheral side of the combustion chamber is relatively smaller than that of the opening on the upper wall 7a side, the engine stratified combustion operation is performed. At this time, by closing the shutter valve 17 arranged on the upper wall 7a side, the intake flow N deflected downward of the intake port 7 can be smoothly flowed along the lower wall portion 7b. .

The axis 7A may be gently curved to the extent that a large turbulent intake air flow does not occur in the intake port 7. Further, regarding the cross-sectional shape of the intake port 7 located upstream of the throat portion 73, the opening area of the opening located on the upper wall 7a side with respect to the vertical centerline C has a larger opening area than the lower wall 7b side. The shutter valve 17 may be used to open and close the opening on the side of the lower wall 7b.

In the above embodiment, in the engine provided with the pair of intake ports 7, 7 having the downstream end opened into the combustion chamber 5, the injector 12 is arranged on the outer peripheral side of the combustion chamber between the intake ports 7, 7. At the same time, the spark plug 11 is disposed on the center side of the combustion chamber between the intake ports 7 and 7,
The opening located on the lower wall 7b side of the
Has an eccentric shape that is located on the opposite side of the intake port 7 adjacent to the position of the center of gravity O of the entire opening, without causing the problem that the injector 12 interferes with the installation portion of the ignition plug 11 and the intake valve 9, Both intake ports 7,7
By effectively utilizing the space formed on the lower wall side 7b between them, the injector 12 can be disposed in this portion. Therefore, during the stratified charge combustion operation, the injector 1 is not impaired without impairing the above-mentioned effect of increasing the strength of the tumble flow T by deflecting the flow of intake air toward the lower wall 7b.
There is an advantage that 2 can be arranged at an appropriate position.

In particular, as shown in the above embodiment, the opening of the intake port 7 on the side of the upper wall 7a is formed in a substantially rectangular shape, and the opening on the side of the lower wall 7b is formed in a substantially triangular shape with a downward constriction. In this case, both intake ports 7,
Since a space for disposing the injector 12 can be formed on the side of the lower wall 7b between the injectors 7, the injector 12 can be compactly arranged in the state where the injector 12 is close to the intake ports 7, 7. Then, when the engine is in the low rotation speed operation region, the opening portion on the side of the upper wall 7b formed in the substantially rectangular shape is closed by the shutter valve 17, and the intake flow is formed in the lower wall 7b formed in the substantially triangular shape. By deflecting to the side opening, the flow velocity of the intake air can be effectively increased, and the intake flow can be efficiently swirled along the inner surface of the side wall portion of the intake port 7.

Further, as shown in the above embodiment, a pair of intake ports 7, 7 whose downstream ends are opened into the combustion chamber 5 and a single intake passage 15a are directed toward the pair of intake ports 7, 7. In the spark ignition type engine having the common portion 16 that branches, the intake port 7 along the cylinder axis 2A
When viewed from the direction orthogonal to the vertical cross section of the intake port 7, when the installation portion of the valve guide 13 of the intake port 7 to the common portion 15 is formed in a substantially straight shape, the intake air is introduced from the common portion 16 along the intake port 7. And the intake air flow deflected to the lower wall 7b side by the shutter valve when the engine is in the low rotation speed operation region, the passage center O of the opening on the lower wall 7b side
By guiding to the b side, the intake air can be effectively swirled from the lower wall 7 side along the inner surface of the side wall portion.

Moreover, in the above embodiment, the installation portion of the shutter valve 17 and the common portion 16 are connected to the intake manifold 15.
In addition, since the intake manifold 15 and the intake port 7 formed in the cylinder head 3 are connected to each other in a substantially straight shape when viewed from a direction orthogonal to a longitudinal section of the intake port 7 along the cylinder axis 2A, When the engine is in a low rotation speed operating region, the intake manifold 15 provided with the common portion 16 and the like can be effectively used to increase the flow velocity of intake air, and the swirling of intake air can be effectively promoted. You can

In particular, as shown in the above embodiment, a pair of intake ports 7, 7 whose downstream ends open into the combustion chamber and a single intake passage 15a branch toward the pair of intake ports 7, 7. In the engine including the common portion 16, the shutter valve 17 is arranged at the downstream end portion of the common portion 16, and the upper wall 7a of the intake passage between the portion directly upstream of the throat portion 73 and the common portion 16 is provided. , 16a
Side opening is formed in a substantially rectangular shape, and the lower wall 7
Since the openings on the b and 16b sides are formed in a downwardly constricted substantially triangular shape, the intake flow according to the outward vector N1 generated when the intake flow reaches the common portion 16 from the single intake passage 15a. Since the swirling of the intake valve 9 can be further effectively promoted, it is possible to more effectively suppress the intake flow N from colliding with the upper surface of the umbrella portion of the intake valve 9 during the stratified combustion operation of the engine. .

Further, in the above embodiment, the cylinder axis 2
The inclination angle of the upper wall 7a of the intake port 7 with respect to A is greater than that of the upstream side portion 71 of the installation portion of the valve guide 13,
The downstream side portion 72 of the valve guide 13 has an upstream portion 7
2a is large and the downstream portion 72b thereof is small, and the inclination angle of the lower wall 7b of the intake port with respect to the cylinder axis 2A is smaller than that of the upstream side portion 71 of the installation portion of the valve guide 13 in the downstream side portion. Since 72 is formed to be large, the shutter valve 17 is closed as shown in FIG. 10 during the stratified charge combustion operation at low load and low rotation, so that the intake flow deflected to the lower wall 7b side of the intake port 7 is decreased. When N reaches the downstream side portion 72,
Along the lower wall 7b, the upper wall 7a side (exhaust port 8
Side) will be guided.

Therefore, while suppressing the main flow of the intake air flow N from colliding with the combustion chamber outer peripheral side portion 9b of the umbrella valve upper surface 9a of the intake valve 9, the combustion chamber center side portion 9a of the intake valve 9 upper surface of the umbrella valve portion.
Or, by introducing the intake air into the combustion chamber 5 at a predetermined angle along the upper wall 7a, an appropriate tumble flow T is generated, and the tumble flow T is prevented from disappearing at an early stage until the latter half of the compression stroke. Since the tumble flow T can remain, the stratification of the air-fuel mixture can be promoted and the combustion stability can be effectively improved.

FIG. 11 shows an example of the present invention constructed as described above.
As shown in, the intake port 7 with respect to the cylinder axis 2A
An experiment was conducted to measure the change in the ventilation resistance of the intake air in a comparative example in which the inclination angles of the upper wall and the lower wall were substantially straight, and the data shown in FIG. 12 were obtained. In the above data, the vertical axis is the flow coefficient Cf representing the ventilation resistance, and the horizontal axis is the tumble ratio Tr. The tumble ratio Tr is a value obtained by dividing a value obtained by measuring and integrating the vertical angular velocity of the intake air flow for each valve lift by the engine angular velocity.

From the above data, the shutter valve (S valve) 7
In the stratified charge combustion region in which the
As shown by the broken line, the tumble ratio Tr cannot be increased so much, whereas in the example of the present invention, the tumble ratio Tr can be made sufficiently large as shown by the solid line, and the tumble ratio Tr is higher than that of the comparative example. It was confirmed that the maximum value of Tr was increased by ΔTr1.

Further, in the above embodiment, since the intake port 7 is formed so that the effective passage area of the intake port 7 in the downstream side portion 72 of the installation portion of the valve guide 13 is larger than that in the upstream side portion thereof, the required intake air amount In addition, there is an advantage that it is possible to effectively prevent the occurrence of a situation in which the intake air amount becomes insufficient due to an increase in the intake ventilation resistance during the uniform combustion operation with a large fuel injection amount. An example of the present invention in which the effective passage area of the intake port 7 in the downstream side portion 72 is larger than that of the upstream side portion 71, and as shown in FIG. 11, the effective passage area of the intake port 7 in the downstream side portion 72 is set to the upstream side portion. An experiment was conducted to measure the change in the air intake resistance of the intake air in the comparative example having a size smaller than 71, and the data shown in FIG. 12 were obtained.

From the above data, the shutter valve (S valve) 7
In a uniform combustion region with the full open state, in the comparative example,
As indicated by the broken line of the shutter valve, the flow coefficient Cr cannot be made so small, whereas in the example of the present invention,
When the shutter valve (S valve) 7 is fully opened as shown by the solid line, the flow coefficient Cr can be sufficiently reduced, and the minimum value of the intake resistance is ΔCf as compared with the comparative example.
It was confirmed that it can be made smaller.

Moreover, in the comparative example (FIG. 11) in which the effective passage area of the intake port 7 in the downstream side portion 72 is smaller than that in the upstream side portion 71, the shutter is released during the uniform combustion operation in which the required intake air amount and the fuel injection amount are large. Even if the valve (S valve) is set to the maximum open state, it is inevitable that the flow velocity of the intake air in the downstream portion 72 becomes high to some extent, so that there is a tendency for an overtumble state in which an unnecessarily large tumble flow T is generated. . Therefore, during the uniform combustion operation, a part of the fuel injected from the injector 12 is carried by the tumble flow T and adheres to the ceiling of the combustion chamber 5, the cylinder inner wall surface, the piston upper surface, etc. to easily become an unburned state. However, there is a problem that the amount of smoke and HC generated increases and the emission property deteriorates, and in addition to the high combustion temperature, abnormal combustion such as knocking easily occurs.

On the other hand, as in the above embodiment, the intake port 7 is formed so that the effective passage area of the intake port 7 in the downstream side portion 72 of the installation portion of the valve guide 13 is larger than that in the upstream side portion 71. In this case, during the uniform combustion operation in which the required intake air amount and the fuel injection amount are large, the downstream portion 7
Since the flow velocity of the intake air in 2 does not become excessively high, the tumble ratio Tr can be reduced by ΔTr2 as compared with the comparative example, as shown in FIG. Therefore, by preventing the occurrence of the overtumble, there is an advantage that the emission property can be maintained in a good state and the occurrence of knocking can be effectively prevented.

Moreover, as shown in FIG. 11, the downstream side portion 7
2, the effective passage area of the intake port 7 is set to the upstream side portion 71
In a comparative example in which the intake air flow rate is smaller than the above, even when the shutter valve (S valve) is set to the maximum open state during the uniform combustion operation in which the required intake air amount and the fuel injection amount are large, the flow velocity of the intake air can be significantly reduced in the downstream portion 72. Since this is not possible, there is a tendency for an overtumble state in which an unnecessarily large tumble flow T is generated. Therefore, during uniform combustion operation, the fuel spray is carried by the tumble flow T and easily adheres to the ceiling portion of the combustion chamber 5, the inner wall surface of the cylinder, the upper surface of the piston, etc., and the amount of smoke and HC generated increases, and the emission is increased. And the combustibility becomes too good due to the above-mentioned over-tumble, and knocking is likely to occur.

On the other hand, as shown in the above embodiment, the intake port 7 is formed so that the effective passage area of the intake port 7 in the downstream side portion 72 of the installation portion of the valve guide 13 is larger than that in the upstream side portion 71. In this case, the flow velocity of the intake air in the downstream portion 72 does not become excessively high during the uniform combustion operation in which the required intake air amount and the fuel injection amount are large. Therefore, the occurrence of the overtumble is prevented and the emission property is improved. There is an advantage that it can be maintained in a good state and that knocking can be effectively prevented.

Further, in the above-described embodiment, when the intake valve 9 is fully lifted, the downstream side portion 7 of the installation portion of the valve guide 13 is
2, the extension line 72B of the lower wall 7b and the intake valve 9
The inclination angle of the lower wall 7b is set so that the intersection point P with the bottom surface of the intake valve 9 is located closer to the center of the combustion chamber 5 than the axis 9A of the intake valve 9.
There is an advantage that the main flow of the intake flow N can be effectively suppressed from colliding with the upper surface of the umbrella portion of the intake valve 9.

Further, as shown in the above embodiment, the corner portion 7 is formed at the connecting portion between the downstream side portion 72 of the installation portion of the valve guide 13 and the throat portion 73 on the lower wall 7b side of the intake port 7.
When 4 is formed, during stratified combustion operation of the engine,
The intake air flow N along the lower wall 7 is disturbed to form a turbulent flow consisting of small vortexes, and the turbulent flow causes the intake air flow N to flow.
The action of guiding the above to the upper wall 7a side (the side where the exhaust port 8 is installed) is promoted. Therefore, as described above, by providing the guide portion for forming the turbulent flow including the corner portion 74 and the like at the connecting portion between the downstream side portion 72 and the throat portion 73, the main flow of the intake air flow N becomes the main flow of the intake valve 9. While suppressing the collision with the combustion chamber outer peripheral side portion 9b on the upper surface of the umbrella portion, the intake valve 9
The effect of making the appropriate tumble flow T into a substantially triangular shape is effective by inhaling the intake air into the combustion chamber 5 at a predetermined angle along the side portion 9a or the above-mentioned upper wall 7a. There is an advantage that it can be obtained.

In the above embodiment, the direct-injection type engine in which the fuel is directly injected into the combustion chamber 5 from the injector 12 arranged at the peripheral portion of the combustion chamber 5 has been described.
The present invention is also applicable to a port injection type engine configured to inject fuel into the intake port 7.

[0064]

As described above, according to the present invention, the intake port whose downstream end opens into the combustion chamber, the intake valve that opens and closes the intake port, and the peripheral portion of the intake port in the low engine speed region. And a shutter valve that deflects the flow of intake air by closing the valve section, and a part of the valve guide wall that supports the intake valve projects into the intake port on the upper wall located on the center side of the combustion chamber of the intake port. In the spark ignition engine provided so that the cross-sectional shape of the intake port located upstream of the throat portion is either the upper wall side or the lower wall side of the vertical center line of the opening. Is formed so that the opening area of the opening located at is relatively smaller than the other, and the opening having a small opening area is
Since the center of the passage has an eccentric shape located outside the center of gravity, and the shutter valve is arranged on the opening side with a large opening area to open and close this portion, the engine In the rotating region, while preventing the main flow of the intake flow from colliding with the upper surface of the head portion of the intake valve, by introducing the intake air into the combustion chamber, an appropriate tumble flow is generated and stratification of the air-fuel mixture in the combustion chamber. There is an advantage that the combustion stability can be effectively improved by promoting the above.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a main part of an engine including an intake device according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of a combustion chamber and an intake system of the engine.

FIG. 3 is an explanatory view showing a vertical sectional shape of an intake port.

FIG. 4 is an explanatory view showing a cross-sectional shape of an intake port.

FIG. 5 is a graph showing a change state of an effective passage area of an intake port.

FIG. 6 is an explanatory diagram showing a fuel injection state.

FIG. 7 is an explanatory diagram showing a specific structure of a shutter valve.

FIG. 8 is a map showing a combustion region of the engine.

FIG. 9 is an explanatory diagram showing a flow state of intake air.

FIG. 10 is an explanatory diagram showing a flow state of intake air.

FIG. 11 is an explanatory diagram showing a configuration of a comparative example for the present invention.

FIG. 12 is a data diagram showing a correspondence relationship between a tumble ratio and a flow resistance.

[Explanation of symbols]

2A cylinder axis 5 Combustion chamber 7 intake port 7a Upper wall 7b Lower wall 7A Intake port axis 7B Extension of lower wall 9 intake valve 11 Spark plug 12 injectors 13 Valve guide 17 Shutter valve C upper and lower center line 71 upstream side 72 Downstream side 73 Throat

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 9/02 361 F02D 9/02 361A 9/10 9/10 A F02F 1/42 F02F 1/42 D F (72) Inventor Takayuki Yamada 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Kenya Ishii 3-1-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture F-term (reference) 3G023 AA07 AB03 AC04 AD03 AD06 AD07 3G024 AA04 AA09 AA10 AA14 DA00 DA01 DA06 DA08 3G065 CA00 HA10 HA21

Claims (7)

[Claims] 1. An intake port whose downstream end opens into a combustion chamber, an intake valve which opens and closes the intake port, and a part of the peripheral portion of the intake port is closed in a low engine speed region to deflect the flow of intake air. A spark ignition engine having a shutter valve and a valve guide wall that supports the intake valve, and a part of a valve guide wall that supports the intake valve is provided on an upper wall of the intake port that is located closer to the center of the combustion chamber. In, the cross-sectional shape of the intake port located upstream from the throat,
The opening located on either the upper wall side or the lower wall side of the upper and lower centerlines of the opening is formed to be relatively smaller than the other, and an opening having a small opening area is formed. , The eccentric shape of which the passage center is located outside the center of gravity of the entire opening of the intake port, and the shutter valve is arranged on the opening side with a large opening area to open and close this part. An intake device for a spark ignition engine, which is characterized in that 2. The axis of the intake port located upstream of the installation portion of the valve guide is formed to be substantially straight when viewed from a direction orthogonal to the longitudinal section of the intake port along the cylinder axis, and the intake port The cross section of the intake port is formed so that the opening area of the lower wall side opening located on the outer peripheral side of the combustion chamber is relatively smaller than the opening area of the upper wall side located on the center side of the combustion chamber. An intake device for a spark ignition type engine according to claim 1. 3. A pair of intake ports whose downstream ends open into the combustion chamber, an injector is arranged on the outer peripheral side of the combustion chamber between the intake ports, and an ignition plug is provided on the center side of the combustion chamber between the intake ports. It is characterized in that the opening on the lower wall side of the intake port has an eccentric shape in which the center of the passage is located on the opposite side of the adjacent intake port with respect to the center of gravity of the entire opening of the intake port. An intake system for a spark ignition type engine according to claim 2. 4. The opening of the intake port on the upper wall side is formed into a substantially rectangular shape, and the opening on the lower wall side is formed into a substantially triangular shape with a downward constriction. Intake device for spark ignition type engine. 5. A pair of intake ports each having a downstream end opening into the combustion chamber, and a common portion branching from a single intake passage toward the pair of intake ports, the intake port along the cylinder axis being provided. The spark ignition engine according to any one of claims 1 to 4, wherein a portion from the installation portion of the valve guide of the intake port to the common portion is formed in a substantially straight shape when viewed in a direction orthogonal to the vertical section. Intake device. 6. A shutter valve installation portion and a common portion are provided in the intake manifold, and the intake manifold and the cylinder head are formed when viewed from a direction orthogonal to a longitudinal section of the intake port along the cylinder axis. The intake system for a spark ignition type engine according to claim 5, wherein the intake port and the intake port are connected in a substantially straight shape. 7. A pair of intake ports having a downstream end opening into the combustion chamber, and a common part branching from a single intake passage toward the pair of intake ports, and a downstream end of the common part. A shutter valve is provided, and the opening on the upper wall side of the intake passage between the portion directly upstream of the throat portion and the common portion is formed in a substantially rectangular shape, and the opening on the lower wall side is narrowed downward. 7. The intake device for a spark ignition type engine according to claim 2, wherein the intake device is formed in a substantially triangular shape.