Butterfly valve apparatus and manufacturing method of the same

A butterfly valve apparatus includes a valve body, valve discs, valve shafts, and a connecting member. The valve body has valve passages. Valve discs are respectively arranged in the valve passages. Valve shafts are supported by the valve body such that the valve shafts are aligned substantially in the axial direction of the valve shafts. The plurality of valve shafts respectively support the valve discs. The connecting member connects the valve shafts, which are adjacent to each other. The valve shafts are formed of metal. The connecting member is formed of resin. The valve shafts, which are adjacent to each other, form a gap therebetween in the axial direction of the valve shafts. The valve shafts are connected by forming the connecting member.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and incorporates herein by reference Japanese Patent Application No. 2004-310891 filed on Oct. 26, 2004.

FIELD OF THE INVENTION

The present invention relates to a butterfly valve and a manufacturing method of the butterfly valve. More particularly, the present invention relates to a butterfly valve for a variable intake apparatus of an internal combustion engine and a manufacturing method of the butterfly valve.

BACKGROUND OF THE INVENTION

A conventional variable intake apparatus variably changes a length of an intake passage in accordance with rotation speed of an internal combustion engine to enhance a torque performance of the engine. Specifically, intake air is distributed to either a main passage, which accommodates a valve disc of the butterfly valve, or a bypass passage, through which intake air bypasses the butterfly valve, in a conventional variable intake apparatus, so that the length of the intake air passage is changed in the butterfly valve apparatus.

According to JP-U-61-6648 and JP-U-59-76731, a butterfly valve apparatus includes multiple valve discs, which are respectively supported by multiple valve shafts. The valve shafts are connected with each other, so that the valve discs can be integrally rotated. Furthermore, the valve shafts are connected with each other via spring pins and blade springs, so that thermal expansion arising in the valve shafts is absorbed. Thus, the valve discs can be restricted from causing a disorder.

However, in the structures of the JP-U-61-6648 and JP-U-59-76731, the spring pins and blade springs need to be assembled to the outer peripheries of adjacent valve shafts by hands in narrow spaces between adjacent valve discs. Therefore, time needed for connecting the valve shafts may increase, and total manufacturing time of the butterfly valve may increase.

SUMMARY OF THE INVENTION

In view of the foregoing and other problems, it is an object of the present invention to produce a butterfly valve apparatus and a manufacturing method of the same, such that manufacturing time of the butterfly valve apparatus can be decreased and valve disc can be restricted from causing a disorder.

According to one aspect of the present invention, a butterfly valve apparatus includes a valve body, a plurality of valve discs, a plurality of valve shafts, and at least one connecting member. The valve body has a plurality of valve passages. The plurality of valve discs is respectively arranged in the plurality of valve passages. The plurality of valve shafts is supported by the valve body. The plurality of valve shafts is aligned substantially in an axial direction of the plurality of valve shafts. The plurality of valve shafts respectively supports the plurality of valve discs. The at least one connecting member connects the plurality of valve shafts with each other. The plurality of valve shafts is formed of metal. The at least one connecting member is formed of resin. The plurality of valve shafts includes two valve shafts that are adjacent to each other in an axial direction of the two valve shafts. The two valve shafts, which are adjacent to each other, form a gap therebetween in the axial direction of the two valve shafts. The two valve shafts are connected by forming the at least one connecting member.

A variable intake apparatus includes an intake manifold and the butterfly valve apparatus. The intake manifold has a plurality of branched passages branched from each other. Each branched passage communicates with each valve passage.

A method for manufacturing the butterfly valve apparatus includes a valve disc forming process, a valve body forming process, and a connecting member forming process. The plurality of valve discs is formed of resin in the valve disc forming process in such a manner that the plurality of valve discs is respectively supported by the plurality of the valve shafts. The valve body is formed of resin in the valve body forming process in such a manner that the valve body supports the plurality of the valve shafts. The plurality of valve shafts forms the gap therebetween in the axial direction of the plurality of valve shafts. The at least one connecting member is formed of resin in the connecting member forming process in such a manner that the at least one connecting member connects the plurality of valve shafts, which are adjacent to each other. The connecting member forming process is proceeded after substantially simultaneously proceeding with the valve disc forming process and the valve body forming process.

In the above structure and method, the plurality of valve discs supported by the plurality of valve shafts can be restricted from causing a malfunction due to misalignment, which is caused by thermal expansion and thermal shrinkage, with respect to the plurality of valve passages. Furthermore, time needed for connecting the plurality of valve shafts can be reduced compared with conventional structures, in which plurality of valve shafts are connected with each other using spring pins or blade springs. Thus, manufacturing time for the butterfly valve apparatus and the variable intake apparatus can be reduced.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

First Embodiment

As shown inFIGS. 1A,1B,2, and3, a variable intake apparatus10is mounted in an air intake system, through which intake air is supplied to a V-eight engine of a vehicle, for example. The variable intake apparatus10includes an intake manifold12and a butterfly valve20.

The intake manifold12includes a surge tank14, a low-revolution passage16, and a high-revolution passage18. The surge tank14communicates with a passage downstream of a throttle valve in the intake passage, through which intake air passes after flowing through an air cleaner.

Eight of the low-revolution passages16and eight of the high-revolution passages18are provided corresponding to the number of cylinders of the engine. The low-revolution passages16and the high-revolution passages18construct branched passages of the intake manifold12. Each upstream end of the low-revolution passage16communicates with the surge tank14. Each downstream end of the low-revolution passage16communicates with corresponding cylinder of the engine.

Eight of valve passages30of the butterfly valve apparatus20respectively communicate with the surge tank14. Each upstream end of the high-revolution passage18communicates with corresponding valve passage30. Each downstream end of the high-revolution passage18communicates with a midway of corresponding low-revolution passage16.

As shown inFIGS. 2,4, the butterfly valve apparatus20is constructed of a valve body22, valve shafts24, valve discs26, connecting members28, and the like.

The valve body22is formed of resin. The intake manifold12accommodates the valve body22therein, such that the intake manifold12is fixed to the valve body22. The valve body22includes the valve passages30, which are respectively formed in substantially cylindrical shapes. Four of the valve passages30are drawn up in two lines. The upstream end of each valve passage30communicates with the surge tank14. The downstream end of each valve passage30communicates with corresponding high-revolution passage18. Eight of the valve shafts24are respectively formed of metal to be in a substantially round bar shape. Each valve shaft24is supported by metallic bearings32in the valve body22, such that the valve shaft24passes through corresponding valve passage30. Each valve disc26is formed of resin to be in a disc-shape. The valve disc26is arranged in corresponding valve passage30. Each valve disc26is secured to corresponding valve shaft24passing through the valve passage30. Four valve shafts24respectively pass through four valve passages30arranged to be substantially in one row. The four valve shafts24are substantially coaxially arranged in the axial direction thereof. The four valve shafts24, which are adjacent to each other, are connected via the connecting member28therebetween. Thereby, the four valve discs26are supported by the four valve shafts24, so that the four valve shafts24and the four valve discs26are integrally rotatable.

Next, a connecting structure of the valve shafts24and the connecting members28is described.

As shown inFIG. 1, each end of the valve shafts24has a coupling portion34. The coupling portion34has a crosssectional face, which is substantially perpendicular to the axis of the valve shaft24. The crosssectional face of the coupling portion34is in a substantially semicircular shape. Each coupling portion34has a flat face36, which forms a chord of the semicircular cross section of the coupling portion34. The coupling portions34of the valve shafts24, which are adjacent to each other, engage with each other along the radial direction thereof, such that the flat faces36contact face to face with each other.

The coupling portions34, which are adjacent to each other, form a gap38therebetween in the axial direction thereof. Each flat face36of the coupling portion34is substantially in parallel with the axis of the valve shaft24. The outer peripheries of the valve shafts24, which are adjacent to each other, are covered with the connecting member28, which is formed of resin, so that the adjacent valve shafts24are connected with each other. The resinous material forming the connecting member28is interposed in the gap38formed between the adjacent valve shafts24, so that connecting strength between the adjacent connecting members28is enhanced. The resinous material forming the connecting member28may be selected as appropriate. For example, the resinous material of the connecting member28may be selected from generally known materials, such as polyamide, being reasonably elastic.

A flow amount of intake air is controlled using the throttle valve. The intake air flows into the surge tank14in this variable intake apparatus10after passing through the throttle valve. As shown inFIG. 5, when each valve passage30is closed by corresponding valve disc26, intake air flowing into the surge tank14is supplied into corresponding cylinder of the engine though corresponding low-revolution passage16. As referred toFIG. 2, when each valve disc26opens corresponding valve passage30, intake air flowing into the surge tank14is supplied into corresponding cylinder of the engine though the valve passage30and the high-revolution passage18, in which flow resistance is smaller than flow resistance in the low-revolution passage16.

The length of the flow path of the low-revolution passage16is larger than the length of the flow path of both the valve passage30and the high-revolution passage18. Therefore, an amount of intake air respectively supplied into the cylinders changes corresponding to opening and closing the valve passages30using the valve discs26.

Next, an example of a manufacturing method of the butterfly valve apparatus20used in the variable intake apparatus10is described in reference toFIG. 6. In step S1, as shown inFIG. 7, the metallic valve shafts24, to which the bearings32are respectively assembled, are set in forming dies40, such that four of the metallic valve shafts24are arranged to be in two rows. Subsequently, the forming dies40are tightly closed. In this condition, the valve shafts24, which are axially adjacent to each other, are arranged such that the adjacent valve shafts24axially form the gap38therebetween and the flat faces36of the coupling portions34contact face to face with each other.

Next, in step S2, as shown inFIG. 8, an injection apparatus injects molten resin into the forming dies40to substantially simultaneously form the eight valve discs26and the valve body22. Specifically, the forming dies40form a first cavity42and a second cavity44at predetermined locations therein. Subsequently, molten resin is injected into the first cavity42and the second cavity44. When the molten resin injected into the first cavity42and the second cavity44is cooled to be lower than the grass-transition temperature thereof, the molten resin is solidified, and the routine proceeds to step S3.

In step S3, as shown inFIG. 9, the injection apparatus injects molten resin into the forming dies40to substantially simultaneously form six of the connecting members28. Specifically, the forming dies40form a third cavity46for forming the connecting members28at predetermined locations to surround the coupling portions34of the valve shafts24. The injection apparatus injects molten resin into the third cavity46. When the molten resin injected into the third cavity46is cooled to be lower than the grass-transition temperature thereof, the molten resin is solidified, and the forming dies40is opened. Subsequently, the butterfly apparatus20is removed from the forming dies40to be a product.

In this embodiment, each valve disc26and each valve body22are substantially simultaneously formed of resin. In this case, an amount of thermal expansion of each valve shaft24is apt to be large. However, each connecting member28is formed after the valve disc26and the valve body22are formed, so that each valve shaft24is connected after the valve shaft24is cooled to thermally shrink.

Furthermore, even in the case where the axially adjacent metallic valve shafts24thermally expand when the connecting member28is formed of resin to connect the valve shafts24, the axially adjacent metallic valve shafts24are arranged to form the gap38therebetween and the valve shafts24are cooled earlier than resin, so that the metallic valve shafts24are allowed to thermally shrink in the axial direction thereof. Thus, the valve shafts24are connected with each other in the condition where the valve shafts24sufficiently thermally shrink. That is, the valve shafts24are connected with each other in the condition where a dimensional variation of the valve passages30is absorbed by axial displacement of the valve shafts24caused by thermal shrinkage thereof. Therefore, the valve discs26supported by the valve shafts24can be restricted from causing a malfunction due to misalignment with respect to the valve passages30, for example. Furthermore, in this embodiment, the valve shafts24are connected by forming the connecting members28of resin. Therefore, time needed for connecting the valve shafts24can be reduced compared with conventional structures, in which valve shafts are connected with each other using spring pins or blade springs. Thus, manufacturing time for the butterfly valve apparatus20can be reduced, so that manufacturing time for the variable intake apparatus10can be reduced.

Furthermore, the valve shafts24, which are axially adjacent to each other via the gaps38, may cause thermal shrinkage corresponding to variation in peripheral temperature in such a range between −40° C. and 120° C. in a condition where the variable intake apparatus10is used. However, even in this condition, thermal shrinkage can be absorbed by elastic deformation arising in the connecting members28. Thus, the valve discs26can be restricted from causing a malfunction in the condition where the variable intake apparatus10is used.

In this embodiment, the coupling portions34of the adjacent valve shafts24engage with each other in the radial direction thereof, and the coupling portions34are covered with the connecting members28. Thereby, the adjacent valve shafts24can be restricted from causing torsion with respect to each other in the condition where the variable intake apparatus10is operated. Therefore, the four valve shafts24, which are connected with each other via the connecting members28, and the four valve discs26, which are supported by the four valve shafts24, can be integrally rotated synchronously with each other.

Second to Fourth Embodiments

As shown inFIG. 10, a parallel pin60penetrates the coupling portions34of the valve shafts24, which are adjacent each other, in the radial direction of the valve shafts24in a butterfly valve apparatus50in the second embodiment.

As shown inFIG. 11, two of the valve shafts24, which are adjacent to each other, respectively have coupling portions110,120in a butterfly valve apparatus100in the third embodiment. One coupling portion110of one valve shaft24engages with the other of the coupling portion120of the other of the valve shaft24. The coupling portion110of one valve shaft24has a width across flat structure. Specifically, the coupling portion110of one valve shaft24has substantially flat outer faces112,114, which are substantially in parallel with each other. The substantially flat outer faces112,114are radially apart from each other for the width across flats thereof. Thus, the outer faces112,114of the coupling portion110respectively contact with inner peripheries122,124of the coupling portion120face to face, so that the coupling portions110,120radially engage with each other.

As shown inFIG. 12, coupling portions34of the valve shafts24respectively have flat faces160, which are inclined with respect to the axis of the valve shafts24, in a butterfly valve apparatus150in the fourth embodiment. Specifically, each flat face160is inclined to the outer side in the radial direction of the valve shaft24toward the end face of the valve shaft24(coupling portion34), in this embodiment. Alternatively, each flat face160may be radially inwardly inclined toward the end face of the valve shaft24. Thus, in the structures of this embodiment, the coupling portions34of the valve shafts24, which are adjacent to each other, radially engage with each other, such that the flat faces160contact with each other face to face.

In the above second to fourth embodiments, the metallic valve shafts24, which are axially arranged via the gap38therebetween, are connected by forming the connecting member28. Therefore, the structures of the above second to fourth embodiments can produce effects similar to the effect of the first embodiment.

Variation

The present invention is not limited to the above embodiments. For example, as shown inFIG. 13, the gap38may be axially formed between adjacent end faces of the valve shafts24, without forming the coupling portions34in the adjacent valve shafts24.

The numbers of all the passages16,18of the variable intake apparatus10, the passage30of the butterfly valve apparatus20, the valve shafts24, the valve discs26, and the connecting members28may be modified as appropriate in accordance with the number of the cylinders of the engine, for example.

The butterfly valve apparatus20may be used as at least a part of an apparatus provided to an exhaust system of the engine, in addition to or instead of the variable intake apparatus10provided to the intake system of the engine, for example.

In the above structures, the connecting member is formed of resin such that the connecting member fills the gap axially between the valve shafts, which are axially adjacent to each other. Therefore, strength of the connecting portion between the adjacent valve shafts can be enhanced.

The order of the forming processes of the valve disc, the valve body, and the connecting member may be different from the order of the above embodiment. For example, the forming processes of the valve disc, the valve body, and the connecting member may be performed in this order. Alternatively, the forming processes of the valve body and the connecting member may be simultaneously performed after finishing the forming process of the valve disc.

Various modifications and alternations may be diversely made to the above embodiments without departing from the spirit of the present invention.