Intake manifold

In an intake manifold in which air introduced from an introduction port is fed to each cylinder of an engine by use of multiple ducts which are disposed parallel, a communication space section which provides communication between the introduction port which introduces air and inlets of the ducts is provided, this communication space section is formed so as to extend in a direction in which the inlets of the ducts are arrayed, a funnel section which causes the inlets of the ducts to be arrayed on a same surface is formed in this communication space section, and this funnel section is formed from a single member only in the main body section by providing mating surfaces of the main body section and the duct component member off the funnel section.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an intake manifold for air intake which feeds engine air.

2. Description of the Related Art

There has hitherto been known an intake manifold which is provided in order to feed air to each cylinder of an engine and fabricated from multiple component members, which are formed by techniques such as welding.

Such an intake manifold is provided with multiple ducts each of which communicates with each of the cylinders. And when the intake manifold is formed form multiple divided component members, it is general practice to provide mating surfaces of the component members along the axial direction of the ducts.

A representative example of this construction is described in the Japanese Patent Laid-Open No. 7-148769, for example.

In an intake manifold described in the Japanese Patent Laid-Open No. 7-148769, ducts and space portions provided on the inlet side of the ducts are divided at mating surfaces provided along the axial direction of the ducts, and these are joined together at these mating surfaces to form an internal molded resin part. This intake manifold is constructed in such a manner that the inlets of the ducts themselves are divided at the mating surfaces.

In a case where a funnel portion is provided at the inlets of the ducts in order to make the flow of the air smooth, as in the intake manifold described in the Japanese Patent Laid-Open No. 7-148769, if the mating surfaces are provided in such a manner that the inlets of the ducts themselves are divided, the funnel portion itself is also divided.

However, it became apparent that when the intake manifold is constructed by positioning the mating surfaces in the funnel portion, even when the component members are brought into close contact with each other on the mating surfaces, the air flow becomes turbulent in these parts.

Therefore, the present invention provides an intake manifold which can smoothly introduce air into ducts without making the air flow turbulent when a funnel portion is provided at the inlets of the ducts.

SUMMARY OF THE INVENTION

To solve the above-described problem, the present invention provides an intake manifold (1) which comprises a main body section (2) and a duct component member (30) which is fabricated by integrally molding multiple tubular bodies having a sectional shape in circular arc form which are arranged parallel. The duct component member (30) is welded to a surface of the main body section (2), whereby multiple ducts (31) for feeding air to each cylinder of an engine which are arranged parallel are formed. Inlets (18) of each of the ducts (31) are disposed by being arrayed on a same surface in a funnel section (50) which is formed in a communication space section (4) which communicates with the ducts (31) to feed introduced air thereto. A surface of the funnel section (50) is formed, at each of the inlets (18) of the duct (31), by a smooth curved surface which is widened toward the communication space section (4) and this curved surface is continuously connected to an inner circumferential surface of each of the ducts (31). In this intake manifold, by providing mating surfaces of the main body section (2) and the duct component member (30) off the funnel section (50), this funnel section (50) is formed from a single member only in the main body section (2).

In the present invention, for this intake manifold (1), the funnel section (50) is formed in such a manner that an inner side portion thereof which is opposed to an outer shell side of the communication space section (4) protrudes inward from an inner wall surface of the communication space section (4) and bulges outwardly of the inlets (18) of the ducts (31).

Furthermore, in the present invention, for the intake manifold (1), the duct component member (30) is vibration welded to the main body section (2) and formed integrally therewith.

According to the present invention, because the funnel section is formed from a single member, it is possible to cause the air introduced into the intake manifold to flow smoothly from the communication space section which provides communication between the introduction port and the ducts into the ducts without making the air flow turbulent.

Also, undercuts do not occur on the inner side of the funnel section. For this reason, it is possible to perform mold stripping during molding very smoothly.

Furthermore, it is possible to substantially increase the degree of freedom in designing the inclination of the funnel section and the port length of the inlets.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1is a perspective view of an intake manifold1in an embodiment of the present invention. This intake manifold1is used to distribute the air introduced into one introduction port7and causes the air to be introduced into each cylinder of an engine. The intake manifold1is constituted by a main body section2and a duct component member30.

The main body section2is provided with an introduction pipe3which introduces air, a communication space section4which distributes the introduced air and causes the air to flow into a duct31, a duct formation section5which is formed as a duct31which causes the introduced air to circulate, and a head side flange6for connection to an engine head.

The introduction pipe3is provided in such a manner that a leading end thereof extends outward in a side part of the main body section2. This leading end of the introduction pipe3provides the introduction port7. At the leading end of the introduction pipe3which constitutes the introduction port7, there is formed a rectangular connection flange8which bulges outwardly of the introduction pipe3. This connection flange8is provided for connection to an upstream conduit which causes the air to circulate to the intake manifold1, and holes9for tightening bolts are formed at four corners of the connection flange8.

The communication space section4is formed along an end edge of the main body section2, and the side of one end of the communication space section4communicates with the introduction pipe3. Upon a surface wall surface of this communication space section4is formed part of a mating surface with which an end portion of the duct component member is to be mated, and in this part are formed four holes, which are arrayed in the direction in which the communication space section4extends. These holes provide parts which form the inlets18of the ducts31.

The duct formation section5is a section which is formed as part of a peripheral wall of each of the ducts31, and four passages10to13are formed parallel so as to connect the communication space section4and the head side flange6which provides the side of the other end of the communication space section4.

A whole peripheral edge of the duct formation section5is enclosed with a partition14, and a portion which forms the boundary of each of the passages10to13of the duct formation section5is partitioned by partitions15to17. And in these partitions15to17are each formed grooves20at a center in the width direction thereof. Welded protrusions of the duct component member30, which will be described later, are inserted into these grooves20. On the other hand, portions10ato13awhich provide inner circumferential surfaces of the duct31positioned between these partitions15to17are formed as substantially flat surfaces.

On the other hand, in the head side flange6, in positions corresponding to end portions of the ducts31, there are formed holes which pierce through the head side flange6are formed. These holes constitute outlets19of the ducts31.

Next, a description will be given of the duct component member30which is welded to the duct formation section5of the main body section2to form the ducts31.

The duct component member30is a member in which four tubular bodies32to35having a sectional shape in circular arc form are arranged parallel and these tubular bodies are integrally molded by being connected together by a base plate36in flat plate form. InFIG. 1, the bottom end portion of the duct component member30is a portion which is connected to the communication space section4, and the top end portion is a portion which is connected to the head side flange6. Also in this duct component member30, each of the tubular bodies32to35is formed in such a manner that its shape as viewed in a plane extends substantially linearly to correspond to the duct formation section5of the main body section2.

The construction of this duct component member30is such that in the thickness direction thereof, a middle portion30ain the axial direction of the tubular bodies is formed flat without a curve, whereas both ends30b,30cin the axial direction are curved toward the main body section2side.

And at the end portion which is connected to the communication space section4, a flange37which encloses circumferences of the four tubular bodies32to35is formed. The flange37is an end portion of the above-described base plate36. This flange portion37is bent toward the outer side of the intake manifold1and formed to be inclined at an angle with respect to the middle portion of the base plate36.

Also on an end portion (the upper side ofFIG. 1) which is connected to the head side flange6, a flange38which encloses circumferences of the four tubular bodies32to35is formed. Also this flange38is an end portion of the base plate36. This flange38is bent toward the outer side of the intake manifold1and formed to be inclined at an angle with respect to the middle portion of the base plate36.

In this embodiment, though not illustrated, it is preferred that in order to prevent a positional deviation between the main body section2and the duct component member30during vibration welding, claws or ribs with which a jig holding these members during vibration welding be formed in the base plate36.

On the other hand, on a back surface of the duct component member30, as shown inFIG. 3, there is provided a welded protrusion40which is formed so as to enclose the peripheral edge of the base plate36. Furthermore, also in boundary portions of the tubular bodies32to35, welded protrusions41to43are formed along the side edges of these tubular bodies. These welded protrusions40to43are formed at a certain height from the bottom surface of the base plate36.

These welded protrusions40to43are fitted into grooves20formed in the partitions14to17of the duct formation section5of the main body section2. After the fitting of the welded protrusions40to43into the grooves20, the welded protrusions40to43are welded by frictional heat by pressing the duct component member30against the main body section2under minute vibration, whereby the duct component member30is welded to the main body section2.

FIG. 4shows the duct component member30thus constructed is welded to the main body section2. As shown inFIG. 4, in the duct31which is formed by welding the duct component member30to the main body section2, a passage is formed so as to substantially reverse the direction of the flow of air.

That is, on the inlet14side, the axial direction in which the duct31extends is formed so that an inclination angle θ1with respect to the horizontal line becomes not more than 90 degrees, and on the outlet side41, the axial direction in which the duct31extends is inclined so that an inclination angle θ2with respect to the horizontal line becomes not more than 90 degrees. For this reason, the direction of the air which flows through the duct31is changed about 180 degrees according to the inclination of the duct31.

The funnel section50having the function of arraying the inlets18of the ducts31on a same surface is formed in a part of the main body section2on the inlet18side of the duct31. As is apparent fromFIG. 4, the funnel section50formed in the main body section2is fabricated from a single member and has no joint. For this reason, the air which is introduced into the communication space section4through the introduction pipe3from the introduction port7flows smoothly into the duct31without becoming turbulent.

At the inlet18of each of the ducts, this funnel section50is formed so as to be widened outward as the funnel section50extends from the duct31toward the communication space section4. And the surface of the funnel section50is formed from a smooth curved surface and continuously connected to an inner circumferential surface of each of the ducts31. Also as is apparent fromFIG. 4, the funnel section50is formed in such a manner that a portion51of the funnel section50on the outer shell side is formed as an integral curved surface with an inner circumferential surface of the communication space section4without a seam. On the other hand, a portion52on the inner side is formed so as to protrude from the inner circumferential surface of the communication space section4and bulge outwardly of the inlet of the duct31. And a terminal end53of the funnel section50is formed substantially parallel to a mating surface60with the duct component member30.

Incidentally, because there is no undercut on the inner side, i.e., the duct31side of this funnel section50, catches and the like do not occur during the molding of the duct component member30and mold stripping can be very smoothly performed.

In addition, because the funnel section50is fabricated from a single member, it is possible to greatly increase the degree of freedom in designing the inclination of the funnel section50and the port length of the inlet18.