JP2594992Y2 - Engine intake system - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake device for an engine having a siamese type intake port.
The present invention relates to an intake device for an engine having an intake port divided into three parts by a pair of left and right partitions into a central siamese-shaped main port and subports on both left and right sides thereof, and having an injector for injecting fuel into the main port.

[0002]

2. Description of the Related Art In an engine operating region, in a low load region in which the throttle opening is small and the intake air amount is correspondingly small, the mixture is generally set to be rich so as to stabilize combustion. Exhaust gas emissions tend to deteriorate. Therefore, as a measure for improving fuel efficiency and exhaust gas emission, a technique for generating a tumble flow in an intake air-fuel mixture flowing into a cylinder and a technique for stratified combustion for generating a rich air-fuel mixture near an ignition plug have been conventionally known. ing.

[0003] The generation of the tumble flow is to swirl the intake air-fuel mixture along the axial direction of the cylinder. In the latter half of the compression stroke, the tumble flow collapses to generate a strong turbulent flow. By igniting, the combustion speed is high and turbulent combustion with stable combustion can be obtained, which is effective for improving the combustion in the low and medium load region of the engine. In addition, stratified combustion ignites a rich air-fuel mixture generated in the vicinity of a spark plug and promotes combustion by flame propagation. The ignitability is good, combustion is stabilized, and lean combustion having a large air-fuel ratio as a whole is considered. This is effective for improving the fuel efficiency in the low and medium load range of the engine.

Conventionally, a tumble flow is generated in a cylinder in a low-to-medium load region of an engine, and a rich mixture is generated in the vicinity of a spark plug. An intake device has been proposed (see Japanese Patent Publication No. 4-8610). This intake device has a central Siamese-type main port that communicates with the vicinity of the center of the combustion chamber where the ignition plug is installed, inside a Siamese-type intake port that communicates with the combustion chamber through a pair of left and right intake valves. It is divided into a pair of left and right subports located on both left and right sides and communicating with the vicinity of the periphery of the combustion chamber, and an injector for injecting fuel into the main port, and the main port is opened and closed upstream of the injector with respect to the intake air. In the low load region of the engine, the main port is closed by the tumble control valve, fresh air is sucked only from the pair of left and right subports, and fuel is injected from the injector into the main port. A rich air-fuel mixture is formed near the spark plug in the combustion chamber, and a It is obtained so as to generate a table flow.

[0005]

The intake system described in Japanese Patent Publication No. 4-8610 described above is related to the relationship that the injector for injecting fuel into the main port injects fuel toward the siamese separation wall of the main port. In addition, the fuel easily adheres to the Siamese separation wall. Further, since a pair of left and right partition walls dividing the inside of the intake port into a main port and a sub port has its downstream end connected to the valve stem portion of each intake valve, the fuel injected from the injector is above-mentioned. The possibility of adhering to the end of the partition wall on the downstream side of the intake is sufficiently considered. Further, the main port and the pair of left and right sub-ports communicate with each other through a communication opening formed by a notch formed at the end of the partition wall on the intake downstream side, so that the tumble control valve closes the main port. However, there is a possibility that the intake air flows into the main port from the sub port, and the fuel spray is disturbed, and the fuel adheres to the port wall surface.

[0006] As described above, in the intake device described in the above publication, the fuel injected from the injector easily adheres to the wall surface of the intake port, and in particular, the low load of the engine in which the tumble control valve closes the main port. This tendency is large in the area. For this reason, the air-fuel ratio tends to deviate from the set value in the low load region of the engine due to the wall surface of the fuel injected from the injector, and in the transient region of the engine load in which the tumble control valve opens and closes the main port, the air-fuel ratio sharply increases. And the combustion state becomes unstable, and the exhaust gas emission deteriorates.

Further, in the intake device described in the above publication, a pair of left and right partitions dividing the inside of the intake port into a main port and a subport are connected to the stem guide of each intake valve at the downstream end of the intake. In addition, the passage cross-sectional area of the intake port is divided into a main port and a sub-port at a ratio of about 1: 1. For this reason, when the tumble control valve closes the main port and takes in air from only the left and right subports, an intake flow with a sufficient flow velocity cannot be obtained, and the tumble flow generated in the cylinder also becomes weak correspondingly, There was no way to generate a simple tumble flow.

Accordingly, the present invention is directed to an engine which is easy to manufacture, and which can stabilize the air-fuel ratio by preventing the air-fuel ratio from fluctuating or fluctuating due to fuel adhesion to the intake port wall surface. It is another object of the present invention to provide an intake device for an engine capable of generating a strong tumble flow in a cylinder in a low to medium load region of an engine in addition to the main object. .

[0009]

For this purpose, an intake system for an engine according to the present invention has a siamese shape which communicates with a combustion chamber through a pair of left and right intake valves. An intake port divided into three parts, a main port and a pair of subports on the left and right sides of the main port, an injector for injecting fuel into the main port, and an intake upstream of a fuel injection position of the injector only in a low-to-medium load region of the engine. And a tumble control valve that closes the main port on the side, wherein the pair of left and right partitions have a cross-sectional shape with a draft with respect to the master mold dividing surface of the casting core of the intake port. And the end on the downstream side of the intake air is directed to the left and right sides near the stem guide of each intake valve, and Njekuta is a means that it has assumed that the fuel injection in two directions along the main port of the Siamese type.

Further, an air passage for bypassing the tumble control valve to introduce a part of the intake air into the main port is added.

Further, the tumble control valve closes a pair of left and right subports only in a low to middle load region of the engine.

[0012]

In the intake system for an engine according to the present invention employing such means, a pair of left and right partition walls for partitioning a siamese-type main port and a pair of left and right subports each have an intake valve downstream end. The fuel spray injected in two directions along the siamese-type main port from the injector is difficult to adhere. In addition, since the downstream ends of the pair of left and right partitions face the left and right sides of the stem guide of each intake valve, the passage sectional area of the pair of left and right subports is smaller than the passage sectional area of the main port. Demonstrate a sufficient intake throttle effect.

[0013] Therefore, during the intake stroke in the low to medium load region of the engine in which the tumble control valve closes the main port, the fuel injected from the injector along the siamese type main port in two directions flows from the main port. While flowing into the cylinder almost without adhering to the wall,
The intake air is drawn into the cylinder symmetrically at a high flow rate through only the pair of left and right subports, and a strong tumble flow of the intake air is generated in the cylinder in a form enclosing the rich mixture. You. Therefore, in the low to medium load region of the engine, the combustion speed is high, turbulent combustion with stable combustion is reliably performed, and the combustion is improved.

On the other hand, in the intake stroke in the high load region of the engine where the tumble control valve opens the main port, a large amount of intake air is drawn into the cylinder through the main port and the left and right sub-ports, and the charging efficiency is reduced. Increase. At this time, the fuel injected in two directions from the injector along the Siamese-type main port is mixed with the intake air passing through the main port, becomes a uniform mixture, and is sucked into the cylinder. For this reason, in the high load region of the engine, uniform combustion is performed, and high output is obtained.

Here, in the case where an air passage for introducing a part of the intake air into the main port bypassing the tumble control valve is added, the tumble control valve has a low-medium load region of the engine in which the main port is closed. In the intake stroke, a part of the intake air is introduced into the main port through the air passage, and the intake air of the introduced intake air promotes atomization of fuel injected from the injector into the main port. Also, even when fuel adheres to the wall of the main port, vaporization is promoted.

Further, when the tumble control valve closes the pair of left and right subports only in the low-to-medium load region of the engine, during the suction stroke in the low-to-medium load region of the engine, the tumble control valve extends along the Siamese type main port from the injector. The fuel injected in two directions flows into the cylinder without being attached to the wall of the main port, riding on the strong intake flow passing only through the main port, and the tumble flow of the air-fuel mixture flows into the cylinder. Is generated.
Therefore, also in this case, the combustion speed is high and the turbulent combustion with stable combustion is performed to improve the combustion.

Here, from a manufacturing point of view, a pair of left and right partition walls which divide the interior of the intake port into a main port and left and right subports are divided with reference to a master mold dividing surface of the casting core of the intake port. Since the cross section has a draft shape, a casting core corresponding to the pair of left and right partition walls can be formed by only slightly changing the design of the matrix. By using this casting core, the pair of left and right partitions is cast integrally with the intake port.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. In FIG. 2 showing the overall schematic structure of the engine intake device according to the first embodiment, reference numeral 1 denotes an engine main body in which a cylinder head 3 is mounted on a cylinder block 2, and a cylinder 2a of the cylinder block 2
A piston 4 is slidably fitted therein.

As shown in FIG. 1, the cylinder head 3 has a siamese-type intake port 7 and a pair of left and right exhaust valves 8a, 8b communicating with the combustion chamber 6 via a pair of left and right intake valves 5a, 5b. A siamese-type exhaust port 9 communicating with the combustion chamber 6 is formed through the combustion chamber 6, and an ignition plug 10 is installed in the center of the combustion chamber 6. An intake manifold 12 is connected to the cylinder head 3 via an injector holder 11 having an intake passage 11a continuous with the intake port 7 and an injector mounting portion 11b. As shown in FIG. 2, the injector holder 11 communicates the intake port 7 of the cylinder head 3 with the intake manifold 12, and includes a tumble control valve 15, which will be described later, in addition to the injector 11.

Here, the range extending from the downstream portion of the intake passage 11a in the injector holder 11 to substantially the entire region in the intake port 7 is defined by a pair of left and right partitions 13a and 13b and a central siamese main port 7a and the left and right main ports 7a. Divided into a pair of subports 7b and 7c on both sides,
The siamese-type main port 7a communicates with the vicinity of the center of the combustion chamber 6 through a pair of left and right intake valves 5a and 5b, and the pair of left and right subports 7b and 7c respectively communicate with the corresponding one of the intake valves 5a and 5b. It communicates near the periphery of the combustion chamber 6.

On the other hand, the injector mounting portion 11b of the injector holder 11 is connected to the left and right intake valves 5a, 5b along the siamese-shaped main port 7a.
An injector 14 for injecting fuel in the direction is provided. In addition, a tumble control valve 15 that opens and closes an inlet portion of a main port 7a divided by a pair of left and right partitions 13a and 13b is provided in an intake passage 11a of the injector holder 11.

The tumble control valve 15 is a butterfly valve type which is opened and closed by an appropriate actuator (not shown), and closes an inlet portion of the main port 7a in a low-to-medium load region according to an engine load region. In the high load region, control is performed so as to open the inlet of the main port 7a.

Here, the intake port 7 is cast by using a casting core 16 as shown in FIG. 3. In this case, the pair of left and right partition walls 13a and 13b are cast integrally. The casting core 16 has slits 16a and 16b corresponding to the partitions 13a and 13b. This casting core 16 is made up of mother dies 17a, 17 as shown in FIG.
b, the slits 16a, 16a
The cross-sectional shape of b has draft angles of the mother dies 17a and 17b. In this connection, the sectional shapes of the partition walls 13a and 13b integrally cast with the intake port 7 are shown in FIG.
As shown in the figure, the draft core has a draft angle of an angle α with respect to a plane perpendicular to the division plane P of the mother dies 17a and 17b of the casting core 16.

As shown in FIG. 5B, the sectional shape of the partition walls 13a, 13b integrally cast with the intake port 7 is cut off at a portion corresponding to the division plane P of the mother dies 17a, 17b. It may be discontinuous, in which case, the matrix 17a, which corresponds to the shape of the partition walls 13a, 13b,
The casting core 16 formed by 17b is used.

As shown in FIG. 1, the ends of the partition walls 13a and 13b on the downstream side of the intake are spread out near the stem guides 18a and 18b of the intake valves 5a and 5b, respectively, toward the left and right sides. The fuel injected from the injector 14 in two directions along the siamese-shaped main port 7a is unlikely to adhere. In addition, the ends of the partition walls 13a and 13b on the downstream side of the intake air are provided in FIG.
As shown in FIG. 5, acute-angle cutouts 13c and 13d are formed with the center portion corresponding to the division plane P as the tip and directed toward the intake upstream side, and the fuel is injected from the injector 14 in two directions along the Siamese-type main port 7a. It is difficult for the fuel to adhere. The above notch 13
c and 13d are inclined at an angle β with respect to the vertical plane so that the upper edge 13e of the lower edge 13e descends toward the intake downstream side.
By inclining at an angle γ with respect to the horizontal plane so that f advances toward the downstream side of the intake air, the attached fuel is easily dropped into the combustion chamber 6.

On the other hand, as described above, since the downstream ends of the partition walls 13a and 13b are widened in the vicinity of the stem guides 18a and 18b to the right and left sides, the passages of the pair of left and right subports 7b and 7c are provided. The cross-sectional area is smaller than the cross-sectional area of the passage of the main port 7a, so that a sufficient intake throttle effect can be exhibited. In this case, assuming that the passage cross-sectional area of the siamese-type main port 7a is S1, and the total passage cross-sectional area of the left and right subports 7b and 7c is S2, S2 / S1 is 0.6 <(S2 / S1) <1.0. Is preferably set in the range of, for example, S2 /
S1 is set to 0.7.

Next, the operation of the thus-configured engine intake device according to the first embodiment will be described.
In the low and medium load range of the engine, the tumble control valve 15
Closes the main port 7a of the intake port 7,
In the intake stroke of the engine in which the pair of left and right intake valves 5a and 5b open and the piston 4 descends, the intake manifold 1
2 is symmetrically drawn into the cylinder 2a from near the periphery of the combustion chamber 6 at a high flow velocity only through the pair of left and right subports 7b and 7c. And cylinder 2
A high-speed intake air flow sucked symmetrically into the cylinder a collides with the top surface of the piston 4 and reverses upward, so that a strong tumble flow as shown in FIG. 1 is generated in the cylinder 2a. You. On the other hand, fuel injected from the injector 14 in two directions along the siamese-shaped main port 7a is separated from the separation wall 3a and the partition walls 13a, 13a of the main port 7a.
The fuel gas flows into the vicinity of the central portion of the combustion chamber 6 almost without adhering to the wall surface of the main port 7a including the fuel gas b and the like, and is wrapped in the above-mentioned tumble flow to generate a rich mixture near the ignition plug 10.

The rich mixture thus generated is wrapped in the tumble flow of the intake air and stays near the spark plug 10 even in the compression stroke of the engine. The rich mixture near 10 also becomes turbulent. Then, by igniting the turbulent rich mixture directly by the ignition plug 10, stable turbulent combustion with a high combustion speed is reliably performed. Accordingly, lean combustion is possible in the low-medium load region of the engine, and improvement in combustion such as improvement in thermal efficiency and fuel efficiency can be achieved.

On the other hand, in the high load range of the engine, the tumble control valve 15 opens the main port 7a of the intake port 7, so that the pair of left and right intake valves 5a and 5b is opened, and the piston 4 descends. In this case, a large amount of intake air from the intake manifold 12 is sucked into the cylinder 2a through the main port 7a and the pair of left and right subports 7b and 7c, thereby increasing the charging efficiency. that time,
Siamese type main port 7 from injector 14
The fuel injected in two directions along the line a
The mixed gas is mixed with the intake air passing through a and becomes a uniform mixture, and is sucked into the cylinder 2a almost without adhering to the wall surface of the main port 7a. Therefore, in the high load region of the engine, uniform combustion is performed, and high output is obtained.

As described above, in the first embodiment, it is extremely rare that the fuel injected from the injector 14 into the main port 7a adheres to the wall surface of the main port 7a. Hardly go out of order,
Also, when the tumble control valve 15 opens and closes in the transition region between the high load region and the high load region, the ratio between the passage cross-sectional area of the main port 7a and the total passage cross-sectional area of the left and right sub-ports is made appropriate. The air-fuel ratio does not fluctuate rapidly.
Accordingly, the air-fuel ratio is stabilized, and the combustion state is thereby stabilized, and the exhaust gas emission is maintained satisfactorily.

The tumble control valve 15 of the first embodiment has a notch 15a as shown in FIG.
Alternatively, a hole 15b as shown in FIG. 7B may be formed in the peripheral portion as an air passage. Further, a bypass passage 19 of the tumble control valve 15 as shown in FIG. 8 may be provided on the wall of the injector holder 11 as an air passage. In such a case, the tumble control valve 15 is connected to the main port 7a.
During the suction stroke of the engine in the low-to-medium load region, part of the suction air is introduced into the main port 7a through the notch 15a, the hole 15b, or the bypass passage 19, and the introduced intake air flow The atomization of the fuel injected from the injector 14 into the main port 7a is promoted, and even if fuel adheres to the wall surface of the main port 7a, the vaporization of the adhered fuel is promoted.

FIG. 9 shows a double tumble control valve in which the pair of left and right subports 7b and 7c are simultaneously closed only in the low and medium load regions of the engine, instead of using the tumble control valve 15 in the first embodiment described above. The second embodiment of the present invention is provided with the same reference numerals as those of the first embodiment.

In the second embodiment, the dual tumble control valve 20 closes the pair of left and right sub-ports 7b and 7c in the intake port 7 in the low and medium load region of the engine, so that the pair of left and right intake valves 5a and 5b Is opened and the piston 4 descends, the intake air from the intake manifold 12 mixes with the fuel injected from the injector 14 and flows only through the central main port 7a near the center of the combustion chamber 6 during the intake stroke of the engine. Symmetrically from cylinder 2
a. Therefore, in this second embodiment,
A tumble flow of the air-fuel mixture is generated in the cylinder 2a. In this case also, turbulent combustion with a high combustion speed and stable combustion is performed to improve combustion.

In the second embodiment, the fuel injected in two directions along the siamese-type main port 7a from the injector 14 during the suction stroke of the engine in the low-to-medium load region is supplied to the main port as described above. Riding on a strong intake flow passing only through 7a, it flows into the cylinder 2a almost without adhering to the wall surface of the main port 7a. Therefore, also in the second embodiment, similarly to the first embodiment, the air-fuel ratio does not deviate from the set value in the low-to-medium load region, and the tumble control valve 15 in the transition region between the high-load region. The air-fuel ratio does not fluctuate abruptly when the valve is opened and closed, the air-fuel ratio is stabilized, and accordingly, the combustion state is stabilized, and the exhaust gas emission is maintained well.

[0035]

As described above, the present invention employs an injector that injects fuel in two directions along a siamese-type main port, and a pair of left and right partitions partitioning the main port are provided at the downstream end of the intake. The fuel is injected in two directions along the siamese-type main port from the injector because the basic means is to open the right and left sides of the stem guide of each intake valve to the left and right sides, respectively. Is sucked into the cylinder almost without adhering to the wall surface. Therefore, according to the present invention, it is possible to stabilize the air-fuel ratio by preventing deviation and fluctuation of the air-fuel ratio due to fuel adhesion, stabilize the combustion state, and maintain good exhaust gas emission. it can.

Further, in the present invention, since the downstream end portions of the pair of left and right partitions face the left and right sides of the stem guide of each intake valve, the passage cross-sectional area of the pair of left and right subports is equal to that of the main port. It is small compared to the passage cross-sectional area and exhibits a sufficient intake throttle effect. Therefore, according to the present invention, in the intake stroke in the low and medium load region of the engine in which the tumble control valve closes the main port, the intake air flows through the pair of left and right sub-ports at a high flow rate and symmetrically in the cylinder. Thus, a strong tumble flow can be generated in the cylinder, and the combustion speed can be increased, and turbulent combustion with stable combustion can be reliably performed to improve combustion.

Also, from a manufacturing viewpoint, a pair of left and right partitions dividing the inside of the intake port into a main port and a pair of left and right subports are formed on the basis of the master mold dividing surface of the casting core of the intake port. Since it has a cross-sectional shape with a draft angle, a casting core corresponding to the pair of left and right partitions can be created by only slightly changing the design of the matrix, and by using this casting core, the pair of left and right Since the partition wall can be cast integrally with the intake port, it is not necessary to form the partition wall by a separate member and mount it in the intake port, which facilitates manufacture.

Here, in the case where an air passage for bypassing the tumble control valve and introducing a part of the intake air into the main port is added, the tumble control valve has a low-medium load region of the engine in which the main port is closed. In the intake stroke, a part of the intake air is introduced into the main port through the air passage, so that the intake air of the introduced intake air atomizes the fuel injected from the injector into the main port. , And vaporization can be promoted even when fuel adheres to the wall surface of the main port.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a first embodiment of an intake device for an engine according to the present invention, showing the overall schematic structure and operation of an intake port.

FIG. 2 is a vertical cross-sectional view of the vicinity of an intake port for explaining the overall schematic structure and operation of the first embodiment.

FIG. 3 is a perspective view of a casting core of the intake port in the first embodiment.

FIG. 4 is a schematic sectional view of a matrix for molding a casting core of an intake port in the first embodiment.

FIG. 5 is a diagram showing a sectional shape of a partition wall in the first embodiment.
5A is a cross-sectional view taken along the line V-V of FIG. 5A, wherein FIG.

FIG. 6 is a sectional view showing the shape of the end of the partition wall on the downstream side of the intake air in the first embodiment.

FIGS. 7A and 7B are front views showing different modified examples of the tumble control valve in the first embodiment.

FIG. 8 is a sectional view of an injector holder showing a bypass passage added to the first embodiment.

FIG. 9 is a cross-sectional view corresponding to FIG. 1, showing the overall schematic structure of a second embodiment of the engine intake device according to the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine main body 2 Cylinder block 2a Cylinder 3 Cylinder head 3a Separation wall 4 Piston 5a, 5b Intake valve 6 Combustion chamber 7 Intake port 7a Main port 7b, 7c Subport 8a, 8b Exhaust valve 9 Exhaust port 10 Ignition plug 11 Injector holder 11a Intake Passageway 11b Injector mounting part 12 Intake manifold 13a, 13b Partition wall 13c, 13d Notch 13e Upper edge 13f Lower edge 14 Injector 15 Tumble control valve 15a Notch 15b hole 16 Casting core 16a, 16b Slit 17a, 17b Master mold 18a, 18b Stem guide 19 Bypass passage 20 Double tumble control valve

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 69/00 360 F02M 69/00 360C 69/04 69/04 R (72) Inventor Takayoshi Kawaharahata 1-chome, Nishishinjuku, Shinjuku-ku, Tokyo No. 2 Inside Fuji Heavy Industries Ltd. (56) References JP-A-55-139924 (JP, A) JP-A-63-71425 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) ) F02M 69/00 360 F02B 31/00

Claims (3)

(57) [Scope of request for utility model registration] 1. A siamese type that communicates with a combustion chamber via a pair of left and right intake valves, and is internally divided into a central siamese type main port and a pair of left and right subports by a pair of left and right partitions. An intake system for an engine, comprising: an intake port, an injector that injects fuel into the main port, and a tumble control valve that closes the main port upstream of the fuel injection position of the injector only in a low-to-medium load region of the engine. In the pair of left and right partitions, the intake port has a cross-sectional shape with a draft with reference to the mother die division surface of the casting core of the intake port,
In addition, the downstream end of the intake valve faces the left and right sides near the stem guide of each intake valve, and the injector injects fuel in two directions along the siamese-type main port. An intake device for an engine, characterized by: 2. An intake system for an engine according to claim 1, further comprising an air passage for bypassing said tumble control valve and introducing a part of intake air into said main port. 3. The intake system for an engine according to claim 1, wherein the tumble control valve closes the pair of left and right subports only in a low to middle load region of the engine.