JP3541597B2 - Engine intake port - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement in an intake port of an engine. More specifically, the present invention relates to a shape of a helical port capable of generating a strong swirl having a swirl ratio exceeding 6 as an intake port of a diesel engine.
[0002]
[Prior art]
In the case of a direct-injection diesel engine, swirl is actively used to promote mixing of the injected fuel and air to enhance the combustibility. Swirl is the swirling airflow that occurs around the cylinder axis throughout the intake stroke of the engine, and the intake port plays an important role in its generation. Of these, a helical port that forms a downstream end portion of the port in a spiral shape and generates a swirling flow around the axis of the intake valve when the intake air passes therethrough is often employed. The helical port is composed of a throat portion opening to the ceiling surface of the combustion chamber, a spiral swirl passage portion (scroll portion) communicating with the throat portion from above, and a straight passage portion on the upstream side thereof.
[0003]
Japanese Patent Laid-Open Publication No. Sho 59-12123 discloses that a spiral shape on a plan view of an intake port is defined so as to achieve both enhancement of swirl and improvement of volumetric efficiency. Changing the height of the opening changes the swirl generation ability. Therefore, even if only the spiral shape on the plan view of the helical port is specified, it is difficult to achieve both high swirl and high volumetric efficiency at the same time.
[0004]
In order to improve this point, in the helical port, the height of the throat opening is determined by changing the swirl ratio required for engine performance, the opening diameter of the cylinder, the stroke of the piston, the cross-sectional area of the starting position of the swirl passage, and the swirl passage. Strong swirl with swirl ratio exceeding 6 by defining as a function of the angle of descent of intake air in the section, the opening diameter of the throat section, and the angle between the flow center of gravity of the throat opening and the optimum outflow position with respect to the center of the throat. Is also available (JP-A-8-244982).
[0005]
[Problems to be solved by the invention]
However, when the height of the throat opening is set low in order to obtain a high swirl ratio, the lower end surface of the valve guide boss forming the ceiling wall of the throat is also lowered, so that the length of the valve guide is increased. In a four-valve direct-injection diesel engine, a helical type and a tangential type are often used in combination as a swirl port. In this case, since the lower end surface of the valve guide boss is set at a relatively high position in the tangential port, the length of the valve guide differs from that of the helical port where the height of the throat opening is low. For this reason, valve guides having different lengths are required, which causes a problem of increasing parts costs and equipment costs.
[0006]
The present invention has been made in view of such a problem, and enables the valve guide of the tangential port and the valve guide of the helical port to be shared.
[0008]
[Means for Solving the Problems]
According to a first aspect of the present invention, in an engine having a tangential port and a helical port for each cylinder as a swirl port to a cylinder, a valve guide is mounted so that a peripheral portion of the helical port is left as a partition wall at a lower end surface of a valve guide boss. A concave portion for increasing the diameter of the hole is formed, and the bottom surface of the concave portion is set at substantially the same height as the lower end surface of the valve guide boss of the tangential port.
[0009]
In the second invention, the recess in the first invention is formed by a mold or machining.
[0010]
According to the third invention, in an engine having a tangential port and a helical port for each cylinder as a swirl port to the cylinder, the lower end surface of the valve guide boss of the helical port is substantially the same as the lower end surface of the valve guide boss of the tangential port. Height is set, and a partition wall is formed along a communication portion between the throat portion of the helical port and the swirl passage portion.
[0011]
In a fourth aspect based on the first or third aspect , the peripheral portion of the partition wall is formed at the edge by machining.
[0013]
[Action]
In the first invention, when the height of the throat opening of the helical port is set low in order to obtain a high swirl ratio, the lower end surface of the valve guide boss of the helical port is also lowered, but the bottom surface of the concave portion leaving the peripheral portion as a partition wall Accordingly, a mounting surface having substantially the same height as the lower end surface of the valve guide boss of the tangential port is secured, so that the same valve guide as the tangential port can be used as the valve guide of the helical port.
[0014]
In the second invention, since the concave portion is limited around the mounting hole of the valve guide, it can be easily formed even by machining.
[0015]
According to the third aspect, in order to obtain a high swirl ratio, the height of the throat opening of the helical port is set lower by the partition. Since the lower end surface of the helical port valve guide boss is substantially the same height as the lower end surface of the tangential port valve guide boss, the same valve guide as the tangential port can be used as the helical port valve guide.
[0016]
In the fourth aspect , the partition is formed by casting. However, by machining the peripheral portion of the partition, the height accuracy of the partition is improved. In addition, since the control of the flow direction of the intake air works well at the edge of the partition wall, the swirl generation efficiency can be improved.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
1 and 2, a helical port 2 and a tangential port 3 are connected to a cylinder 1. These ports 2 and 3 are formed so as to open to one side wall of the cylinder head and extend toward the cylinder 1. Although not shown, two exhaust ports are connected to the cylinder 1. A fuel injection valve faces the center of the cylinder 1. When fuel is injected from the injection valve, the fuel mixes with air taken into the cylinder 1 and ignites and burns while being compressed by the piston.
[0018]
The helical port 2 includes a straight passage section 30, a swirl passage section 20, and a throat section 10. The throat portion 10 is formed in a cylindrical shape that opens to the lower surface of the cylinder head, and communicates with the swirl passage portion 20 through a throat opening 10a at the upper portion thereof. The swirl passage portion 20 connects the straight passage portion 30 and the throat portion 10 and is spirally curved. An intake valve (not shown) is arranged on the center line P of the throat portion 10, and is slidably supported by the valve guide 4 via its shaft portion. The valve guide 4 is fitted into the mounting hole 6a of the valve guide boss 6 by press fitting.
[0019]
The tangential port 3 is formed so that its downstream side is substantially parallel to a tangent line of the cylinder 1 in a plan view. An intake valve (not shown) is arranged on the center line Q of the port opening 3a on the cylinder 1 side, and is slidably supported by the valve guide 5 via its shaft. The valve guide 5 is fitted into a mounting hole 9a of the valve guide boss 9.
[0020]
In the helical port 2, the height of the throat opening 10a is set low so as to obtain a high swirl ratio. The tangential port 3 is set at a position where the lower end surface of the valve guide boss 9 is relatively high. Therefore, the lower end surface of the valve guide boss 6 of the helical port is lower than the lower end surface of the valve guide boss 9 of the tangential port 3.
[0021]
In order to match the mounting surfaces of the valve guides 4 and 5 while keeping the height of the throat opening 10a low, a concave portion 7 is provided on the lower end surface of the valve guide boss 6 of the helical port 2 to increase the diameter of the mounting hole 6a. . The concave portion 7 is formed by casting or machining, and its bottom surface is set to be substantially the same height as the lower end surface of the valve guide boss 9 of the tangential port 3 with the valve guide 4 mounting surface. The valve guide boss 6 is left around the recess 7 to form a partition wall 8 that keeps the height of the throat opening 10a low.
[0022]
The valve guide 4 of the helical port 2 has the same length as the valve guide 5 of the tangential port 3. The valve guide 4 is shorter than the length of the valve guide boss 6, and its lower end is retracted into the recess 7. In the tangential port 3, the amount of protrusion of the valve guide 5 from the lower end surface of the valve guide boss 9 is set to be large, while in the helical port 2, the amount of protrusion of the valve guide 4 to the concave portion 7 is set to be small. The amount of depression of the recess 7 can be minimized.
[0023]
With such a configuration, the valve guide 5 of the tangential port 3 and the valve guide 5 of the helical port 2 are shared parts having the same length. Since only one type is required, such as a driving machine and a parts feeder, equipment costs can be reduced. Further, since the valve guide 4 of the helical port 2 is shortened, the sliding friction of the valve is reduced, so that the durability and the fuel consumption are improved.
[0024]
From the viewpoint of sharing parts, it is conceivable that the length of the valve guide 5 of the tangential port 3 is adjusted to the length of the valve guide 4 of the helical port 2. In other words, the longer valve guide 4 may be shared, but in that case, the amount of protrusion of the valve guide 5 to the tangential port 3 becomes large, so that the port flow coefficient and the swirl ratio tend to be reduced. In other words, these shortcomings can be avoided by sharing the shorter one.
[0025]
In FIG. 3, the effect of the concave portion 7 on the flow of intake air to the throat portion 10 will be described. In order to obtain a high swirl ratio, it is necessary to concentrate the flow of the intake air flowing into the throat portion 10 from the swirl passage portion 20 toward the side wall of the throat portion 10 and reduce the flow A toward the center of the throat portion 10. In the case of FIG. 1A, there is a partition wall 8 between the swirl passage section 20 and the throat section 10, and a concave portion 7 is formed inside the partition wall 8, so that a negative pressure that draws intake air toward the center side of the throat section 10 is hardly generated. . For this reason, the flow A that tends to occur in the case of FIG. 2B is reduced, and swirl can be efficiently generated.
[0026]
4 and 5, the lower end surface of the valve guide boss 9 of the helical port 2 is set at substantially the same height as the lower end surface of the valve guide boss 9 of the tangential port 3. In order to set the height of the throat opening 10a low, a partition wall 8 is provided between the throat 10 and the swirl passage 20. The partition wall 8 is formed by a mold, and extends over the entire boundary with the swirl passage section 20.
[0027]
According to this, since the lower end surface of the valve guide boss 9 spreads flat as the ceiling wall of the throat portion 10, the accumulation of carbon and the like is reduced as compared with the concave portion 7, and the swirl generating ability can be favorably maintained. Further, since the partition wall 8 extends over the entire boundary between the swirl passage section 20 and the throat section 10, the control of the flow direction of the intake air by the partition wall 8 works well also in the X region in FIG. improves.
[0028]
In any case, it is desirable to form the edge of the partition 8 at the edge 11 by machining as shown in FIG. When the edge of the partition 8 becomes the edge 11, the controllability of the flow direction of the intake air is improved, and the swirl generation efficiency is further increased. Although the height accuracy of the partition walls 8 has a great influence on swirl generation, variations in the height of the partition walls 8 can be suppressed by machining. That is, the height accuracy of the partition wall 8 is ensured satisfactorily, and the variation of the swirl ratio between the cylinders and the engines is reduced.
[0030]
【The invention's effect】
According to the first invention, in order to obtain a high swirl ratio, while maintaining the height of the throat opening of the helical port low, by providing a recess, the valve guide of the tangential port can be used as the valve guide of the helical port. Can be shared. As a result, in addition to the reduction of component costs and equipment costs, the valve guide of the helical port is shortened, so that the effect of improving the durability and fuel efficiency is obtained by reducing the sliding friction of the valve.
[0031]
According to the second aspect , the recess is not limited to the entire lower end of the valve guide boss but to the periphery of the mounting hole of the valve guide, so that the recess can be easily formed even by machining.
[0032]
According to the third invention, in order to obtain a high swirl ratio, the lower end face of the valve guide boss of the helical port is fixed to the tangential port while maintaining the height of the throat opening of the helical port low by the partition wall. By setting the same height as the lower end face, it is possible to share both valve guides. As a result, the same effect as that of the first invention is obtained.
[0033]
According to the fourth aspect , the height accuracy of the partition wall can be improved, and the control of the flow direction of the intake air by the edge works well, so that the swirl generation efficiency can be improved.
[Brief description of the drawings]
FIG. 1 is a plan view of an intake port representing an embodiment of the present invention.
FIG. 2 is a longitudinal sectional perspective view of the intake port.
FIG. 3 is an explanatory diagram of an intake air flow to a throat portion.
FIG. 4 is a longitudinal sectional perspective view of an intake port showing another embodiment.
FIG. 5 is a plan view of the helical port.
FIG. 6 is an explanatory diagram of machining that represents another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cylinder 2 Helical port 3 Tangential port 4, 5 Valve guide 6, 9 Valve guide boss 7 Depression 8 Partition wall 10 Throat part 10a Throat opening 11 Edge 20 Swirling passage part 30 Straight passage part

Claims (4)

In an engine equipped with a tangential port and a helical port for each cylinder as a swirl port to a cylinder,
A concave portion is formed on the lower end surface of the valve guide boss of the helical port to increase the diameter of the mounting hole of the valve guide boss so as to leave its peripheral edge as a partition,
The bottom surface of the recess was set at approximately the same height as the lower end surface of the tangential port valve guide boss,
An intake port for an engine, characterized in that: The recess is formed by a mold or machining,
The intake port according to claim 1, wherein: In an engine equipped with a tangential port and a helical port for each cylinder as a swirl port to a cylinder,
Set the lower end surface of the valve guide boss of the helical port to approximately the same height as the lower end surface of the valve guide boss of the tangential port,
Forming a partition wall along the communication part between the throat part of the helical port and the swirl passage part,
The partition wall is formed at a position where the inner wall surface is enlarged with respect to the outer diameter of the valve guide of the helical port.
An intake port for an engine, characterized in that: The edge of the partition wall was formed on the edge by machining,
The intake port according to claim 1 or 3, wherein:

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