Air intake device of internal combustion engine

An air intake device of an internal combustion engine comprises a cylinder head having therein two intake ports that are adapted to connect to a cylinder of a cylinder block; and a single partition plate that extends across both the two intake ports so that each of the two intake ports is divided into first and second air passages.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates in general to air intake devices of internal combustion engines, and more particularly to the air intake devices of a type that has two intake ports for each cylinder of a cylinder block of the internal combustion engine.

2. Description of Related Art

Laid-open Japanese Patent Application (Tokkai) 2001-193469 shows an air intake device of the above-mentioned type that is constructed to strengthen a tumbling air flow led to the cylinders of the engine. That is, in the air intake device disclosed by the publication, an elongate partition plate is installed in each intake port in a manner to extend along an axis of the intake port defining upper and lower parallel passages therein. The partition plates are integrally installed in the cylinder head upon casting of the cylinder head. Each partition plate has side edges embedded in a cylindrical wall of the intake port.

SUMMARY OF INVENTION

However, due to its inherent construction, the air intake device of the publication fails to have a satisfied stoutness with which the partition plate is fixed to the cylinder head. Furthermore, when the measures of the publication are applied to neighboring two intake ports, a difficulty arises in positioning the respective partition plates to the two intake ports. That is, if the two partition plates are arranged to lie on the same imaginary plane, a certain but not small distance should be provided between the two intake ports, which would bring about a bulky construction of the intake device.

It is therefore an object of the present invention to provide an air intake device of an internal combustion engine, which is free of the above-mentioned drawbacks.

According to a first aspect of the present invention, there is provided an air intake device of an internal combustion engine, which comprises a cylinder head having therein two intake ports that are adapted to connect to a cylinder of a cylinder block; and a single partition plate that extends across both the two intake ports so that each of the two intake ports is divided into first and second air passages.

According to a second aspect of the present invention, there is provided an air intake device an internal combustion engine, which comprises a cylinder head having therein two intake portions that are adapted to connect to a cylinder of a cylinder block and two exhaust ports that are adapted to connect to the cylinder; and a single partition plate that extends across both the two intake ports so that each of the two intake ports is divided into upper and lower air passages.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following, air intake devices embodying the present invention will be described in detail with reference to the accompanying drawings.

Referring toFIG. 1, there is shown in a sectional manner a cylinder head1which is an air intake device100of a first embodiment of the present invention. A sectional view taken along the line II—II ofFIG. 1is shown in FIG.2.

Cylinder head1is cast from an aluminum alloy or the like.

As is seen fromFIGS. 1 and 2, cylinder head1is formed with two, that is, first and second intake ports3and4for each cylinder2of a cylinder block50. Furthermore, cylinder head1is formed with two exhaust ports5for each cylinder2. Each of intake and exhaust ports3,4and5is provided with an intake or exhaust valve (not shown) that is movably held by a valve guide6or7installed in cylinder head1. That is, when pushed down, each intake or exhaust valve opens the corresponding intake or exhaust opening exposed to a combustion chamber2adefined by cylinder2above a piston (not shown).

As is seen fromFIG. 2, two intake ports3and4are arranged to extend abreast with respect to a direction “P1” of the axis of a crankshaft (not shown) keeping a certain small distance “D” therebetween. That is, two intake ports3and4are put on an imaginary plane “IP” that extends in parallel with the axis of the crankshaft.

As is seen fromFIG. 1, two intake ports3and4extend in parallel with each other from upstream ends8thereof to which an intake manifold (not shown) is connected to downstream ends9thereof which are exposed to combustion chamber2a. It is to be noted that the parallel arrangement of two intake ports3and4may be not so accurate.

As is seen fromFIG. 2, a single partition plate10of metal extends across both two intake ports3and4in such a manner that each intake port3or4is divided into an upper passage3aor4aand a lower passage3bor4bby the plate10. As is seen fromFIG. 1, partition plate10extends from upstream ends8of two intake ports3and4to a position near downstream ends9of the same.

That is, as is seen fromFIGS. 1 and 2, with provision of partition plate10, first or second intake port3or4is divided into an upper passage3aor4aand a lower passage3bor4bwhich are arranged at upper and lower portions with respect to a direction “P2” of an axis of the corresponding cylinder2.

Although not shown in the drawings, at upstream portions of two intake ports3and4, there is arranged a tumbling air flow control valve (not shown) that selectively opens and closes lower passages3band4b. By closing lower passages3band4bby the tumbling air flow control valve thereby causing only upper passages3aand4aof two intake ports3and4to open, the tumbling effect applied to intake air led to the cylinder2is increased or strengthened. With this, a higher fuel efficiency is expected by the engine.

As is seen fromFIG. 2, in this first embodiment, each of first and second intake ports3and4is oval in cross section with its long axis extending in the direction “P2” of the axis of the corresponding cylinder2. Furthermore, in this first embodiment, partition plate10is located just above an imaginary plane “P3” that includes a center axis3cof first intake port3and a center axis4cof second intake port4, so that upper passage3aor4ahas a smaller sectional area than lower passage3bor4b. That is, partition plate10is poisoned nearer to upper passages3aand4athan lower passages3band4b, as shown.

In order to produce the above-mentioned cylinder head1to which the first embodiment of the present invention is applied, the following casting method is employed.

That is, as is shown inFIG. 3, a sand core unit “SCU” having a partition plate10embedded therein is prepared. That is, the sand core unit “SCU” comprises first and second sand cores11and12that are shaped to correspond to first and second intake ports3and4, and partition plate10that has laterally opposed side portions embedded in first and second sand cores11and12. Partition plate10may be constructed of duralumin having a thickness of about 1 to 2 mm. As shown, partition plate10held by sand cores11and12has opposed lateral edge parts14and15and a center narrow part16which are exposed to the outside. As is seen fromFIG. 2, upon completion of casting, these exposed parts14,15and16are embedded in the cast aluminum alloy of the cylinder head1produced.

For practically casting cylinder head1, given numbers of sand core units “SCU” are set in given positions in a sand mold, and a melted aluminum alloy is poured into cavities of the sand mold. After the aluminum alloy is cooled and thus hardened, the sand mold is broken to expose the product, viz., the cylinder head1.

In the following, advantages of the air intake device100with respect to the known air intake device disclosed by the above-mentioned Japanese publication will be described.

First, as is seen fromFIG. 2, partition plate10is supported in cylinder head1through three supporting areas of partition plate10, which are one lateral edge part14, the other lateral edge part15and center narrow part16. As is understood from the drawing, the center narrow part16is steadily embedded in a partition wall of cylinder head1by which two intake ports3and4are separated. This means that the single partition plate10is much tightly held by cylinder head1as compared with the above-mentioned known case wherein the two partition plates are respectively installed in two intake ports3and4. Furthermore, for the same reason, the distance “D” can be much reduced, which induces a compact construction of the air intake device100.

Second, upper and lower passages3aand3bof first intake port3and those4aand4bof second intake port4are can be defined by only one partition plate10. This means reduction in number of parts used and simplification of manufacturing cylinder head1. Furthermore, for the same reason, freedom in layout of partition plate10in cylinder head1is increased.

Referring toFIG. 4, there is shown a sectional view similar toFIG. 2, but showing an air intake device200of a second embodiment of the present invention.

In this embodiment200, each of first and second intake ports23and24has a circular cross section. Furthermore, a partition plate10A used extends in and along the imaginary plane “P3” that includes a center axis23cof first intake port23and a center axis24cof second intake port24. Thus, in this embodiment200, upper and lower passages23aand23bof first intake port23have the same sectional area and those24aand24bof second intake port24have the same sectional area.

Referring toFIG. 5, there is shown a sectional view similar toFIG. 2also, but showing an air intake device300of a third embodiment of the present invention.

In this embodiment300, similar to the above-mentioned first embodiment100, first and second intake ports33and34have each an oval cross section. In addition, as shown, a partition plate10B used is bent at its center narrow part16to have a generally V-shaped cross section. That is, the center narrow part16of partition plate10B is located on the imaginary plane “P3” that includes a center axis33cof first intake port33and a center axis34cof second intake port34. Furthermore, as shown, laterally opposed portions17and18of partition plate10B are inclined relative to the imaginary plane “P3”. That is, the portions17and18are inclined toward upper passages33aand34arespectively, so that upper passages33aand34ahave each a smaller sectional area than lower passages33band34b, like in the above-mentioned first embodiment100.

The entire contents of Japanese Patent Application 2002-34846 (filed Feb. 13, 2002) are incorporated herein by reference.

Although the invention has been described above with reference to the embodiments of the invention, the invention is not limited to such embodiments as described above. Various modifications and variations of such embodiments may be carried out by those skilled in the art, in light of the above description.