Abstract:
A valve shaft support structure is closed to improve its durability, lower its manufacturing cost and improve its quality, in which a valve shaft interposed between runners is formed as an eccentric shaft integrally formed with a valve. A valve and a valve shaft are formed in a body to support the valve. An eccentric circular protrusion is formed in a center portion of the valve shaft, and divided manifold bodies support the eccentric circular protrusion. The valve shaft and the manifold bodies are repeatedly in contact or non-contact with each other when the valve is opened or closed.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    The present application claims priority to Korean Patent Application No. 10-2008-0068200, filed on Jul. 14, 2008, the entire contents of which is incorporated herein for all purposes by this reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a valve shaft support structure, and more particularly, to a valve shaft support structure for a variable intake manifold, which can improve its durability, lower its manufacturing cost, and improve its quality, through forming of a valve shaft interposed between runners as a shaft integrally formed with a valve. 
         [0003]    An intake manifold is a system of pipes which feeds air sucked through a throttle body into combustion chambers, and serves to uniformly distribute the air to the respective combustion chambers in a multi-cylinder internal combustion engine. 
         [0004]    With the intake manifold, the engine efficiency is varied depending upon the length of a runner, through which the air passes. The length of the runner is preferably long if the engine is driven at a middle or low-speed range, while the length of the runner is preferably short if the engine is driven at a high-speed range. 
         [0005]    As an alternative proposal, a variable induction system (VIS) which varies a length and a cross section of a runner in order to optimize a length and a cross section of an intake manifold depending upon an operation region of an engine has been developed and applied to the engine. 
         [0006]    More specifically, a VIS variable intake manifold may improve the performance through the whole RPM range by opening or closing a valve of the intake manifold to effectively vary a length of the runner through various RPM ranges of an engine. 
         [0007]      FIG. 1  is a view showing a flow of air produced when a valve of a conventional VIS intake manifold is opened or closed. 
         [0008]    As shown in  FIG. 1 , when a valve  1  is opened, a flow of air is indicated by a line C 1 . While the valve  1  is closed, the flow of air is indicated by a line C 2 . 
         [0009]    In the case where the valve  1  is opened, the flow path of air is short. By contrast, in the case where the valve  1  is closed, the flow path of air is long. 
         [0010]      FIG. 2  is a view illustrating a conventional valve shaft support structure in the VIS intake manifold. 
         [0011]    The valve shaft support structure  10  includes a shaft  11  and a bush  13  assembled to the shaft  11 . The shaft  11  is interposed between runners is supported by the separate bush  13 . Since there is no means for damping vibration generated when the engine is driven, the bush  13  supporting the valve shaft  11  and a valve screw (not shown) are released from a proper position. Also, undesired clearance or play may occur between the valve shaft  11  and the bush  13  due to wearing of the valve shaft and the bush, so that the valve shaft  11  becomes loose. 
         [0012]    The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    Accordingly, various aspects of the present invention have been developed to solve the above-mentioned problems occurring in the prior art while advantages achieved by the prior art are maintained intact. 
         [0014]    One aspect of the present invention is to provide a valve shaft support structure for a variable intake manifold, which can improve its durability, lower its manufacturing cost, and improve its quality, through forming of a valve shaft interposed between runners as an eccentric shaft integrally formed with a valve so that the valve shaft comes in contact with a manifold body supporting the valve shaft at predetermined intervals when the valve is opened or closed. 
         [0015]    In order to accomplish these aspects, a valve shaft support structure is provided for a variable intake manifold, which may include at least a valve; a valve shaft integrally formed with the valve to support the valve; a circular protrusion formed substantially in a center portion of the valve shaft; and divided manifold bodies rotatably supporting the circular protrusion therebetween, wherein a portion of the circular protrusion is repeatedly positioned in one of the divided manifold bodies when the valve shaft is rotated so that direct contact of the valve shaft with the divided manifold bodies is prevented. 
         [0016]    Receiving spaces of different size may be formed at a joint portion of each divided intake manifold body and the circular protrusion is positioned in the receiving spaces. 
         [0017]    The circular protrusion may comprise a concentric portion and a protruding portion extending from the concentric portion, the concentric portion being concentric with the valve shaft and the protruding portion formed in an eccentric shape. The protruding portion may be formed substantially along a half circumference of the valve shaft. An inner diameter of the concentric portion and the protruding portion is the same as the outer diameter of the valve shaft, and an outer diameter of the protruding portion is gradually increased in the eccentric shape fro 
         [0018]    m an outer diameter of the concentric portion. 
         [0019]    The valve may be made of plastic. 
         [0020]    The valve shaft may be made of stainless steel. 
         [0021]    The circular protrusion may be formed by overmolding rubber on the valve shaft. 
         [0022]    In another aspect, a valve shaft support structure for a variable intake manifold, may include at least a valve; a valve shaft integrally formed with the valve to support the valve; a circular protrusion formed substantially in a center portion of the valve shaft; and divided manifold bodies rotatably supporting the circular protrusion therebetween, wherein a portion of the circular protrusion is repeatedly positioned in one of the divided manifold bodies when the valve shaft is rotated so that direct contact of the valve shaft with the divided manifold bodies is prevented, wherein receiving spaces of different size are formed at a joint portion of each divided intake manifold body and the circular protrusion is positioned in the receiving spaces, and wherein the circular protrusion comprises a concentric portion and a protruding portion extending from the concentric portion, the concentric portion being concentric with the valve shaft in a predetermined distance from the valve shaft and the protruding portion formed in an eccentric shape by gradually increasing an outer diameter of the protruding portion. 
         [0023]    The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  is a view showing a flow of air produced when a valve of a conventional VIS intake manifold is opened or closed. 
           [0025]      FIG. 2  is a view illustrating a conventional valve shaft support structure for a VIS intake manifold. 
           [0026]      FIGS. 3A ,  3 B,  3 C,  3 D, AND  3 F are views illustrating an exemplary valve shaft support structure according to various aspects of the present invention. 
           [0027]      FIGS. 4A and 4B  are views illustrating a cross-sectional state of the valve shaft support structure in  FIG. 3B . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
         [0029]    A valve shaft support structure according to an exemplary embodiment of the present invention will now be described in detail with reference to  FIGS. 3 to 4 . 
         [0030]      FIGS. 3A to 3F  are views illustrating a valve shaft support structure according to an exemplary embodiment of the present invention. 
         [0031]      FIG. 3A  is a perspective view illustrating an exemplary a housing that accommodates a plurality of intake manifolds therein.  FIG. 3B  is a cross-sectional view taken along line B-B in  FIG. 3A .  FIGS. 3C and 3D  are detail views of the valve shaft in  FIG. 3B .  FIG. 3E  is a cross-sectional view illustrating a circular protrusion formed on the valve shaft according to an exemplary embodiment of the present invention.  FIG. 3F  is a view illustrating the state in which two separate manifold bodies are joined to each other to form a receiving space of different size. 
         [0032]    Referring to  FIGS. 3A to 3F , the valve shaft support structure according to an exemplary embodiment of the present invention includes valves  31  and a valve shaft  33  which are formed integrally at the valves  31 , and an O-shaped circular protrusion  35  formed in a center portion of the valve shaft  33  positioned between the valves  31 . The circular protrusion  35  is supported by intake manifold bodies  51  and  53 , and is rotated therein. 
         [0033]    An intake manifold body supporting the circular protrusion  35  of the valve shaft  33  is divided into two bodies  51  and  53 , as shown in  FIG. 3F . Receiving spaces S 1  and S 2  formed by joining two manifold bodies  51  and  53  are formed in different sizes having different radii. 
         [0034]    For example, a semicircular receiving space S 1  formed by one manifold body  51  is larger than the semicircular receiving space  52  formed by the other manifold body  53  opposite to the receiving space S 1 . 
         [0035]    The circular protrusion  35  is formed in an eccentric shape around the valve shaft  33 , as shown in  FIG. 3E . The circular protrusion  35  comprises a concentric portion  35   c  having an outer diameter of R 1  and a protruding portion  35   a  having an outer diameter increasing from R 1  to R 2 , wherein the protruding portion  35   a  extends from the concentric portion  35   c . The radial distance of the protruding portion  35   a  is gradually increased along a half circumference of the valve shaft  33  in an exemplary embodiment. In this instance, when the circular protrusion  35  is formed, an outer diameter of the concentric portion  35   c  is R 1  but an outer diameter of the protruding portion  35   a  is changed from R 1  to R 2 . 
         [0036]    A stepped portion  35   b  is formed between the protruding portion  35   a  of increased radius R 2  along the outer circumference of the valve shaft  33  and the concentric portion  35   c  having an original radius R 1 . More specifically, when comparing a radius R 1  of the concentric portion with a radius R 2  of an eccentric portion in the circular protrusion  35 , R 1  is shorter than R 2 . 
         [0037]      FIGS. 4A and 4B  are views illustrating a cross-sectional state of the valve shaft support structure in  FIG. 3B  to show variations of a contact state between the valve shaft  33  and the manifold bodies  51  and  53  when the valve is opened or closed. 
         [0038]    Referring to  FIG. 4A  showing the opened valve, the protruding portion  35   a  of the circular protrusion  35  formed at the valve shaft  33  is positioned in the relatively larger receiving space S 1  among the receiving spaces  51  and S 2  which are formed by joining two manifold bodies  51  and  53 . Consequently, the valve shaft  33  does not fully contact with the manifold bodies  51  and  53 , so that the valve shaft  33  is detached or substantially detached from the manifold bodies  51  and  53 . 
         [0039]    Referring to  FIG. 4B  showing the closed valve, the protruding portion  35   a  of the circular protrusion  35  formed at the valve shaft  33  is positioned in the relatively smaller receiving space S 2  to maintain the contact state of the valve shaft  33  and the manifold bodies  51  and  53 . 
         [0040]    Therefore, the valve shaft  33  is formed integrally with the valve  31 , and the circular protrusion  35  is formed substantially in the center portion of the valve shaft  33 , in which the outer diameter R 1  at the concentric portion  35   c  of the circular protrusion  35  is gradually increased to R 2  to form the eccentricity at the protruding portion  35   a . The eccentricity may be formed along a half circumference of the valve shaft  33 . 
         [0041]    The manifold body contacting the circular protrusion  35  and supporting the valve shaft  33  may be divided into two parts  51  and  53 , and the receiving spaces S 1  and S 2  of different sizes are respectively formed in the manifold bodies  51  and  53  when the manifold bodies are joined to each other. Consequently, the protruding portion  35   a  of the circular protrusion  35  is moved in or out from the receiving spaces S 1  and S 2  in accordance with the rotation of the valve  31 . When the valve shaft  33  is repeatedly rotated, the manifold bodies  51  and  53  are rotated at predetermined intervals, thereby improving the durability at the joint portion. 
         [0042]    Also, there is an advantage in that deterioration of the durability is prevented due to the release of a bush mounted on the valve shaft or the loose-fit of a contact portion between the bush and the valve shaft or a separate member and the valve shaft. 
         [0043]    The valve  31  may be made of plastic, and the valve shaft  33  may be made of stainless steel. Preferably, the circular protrusion  35  is formed by overmolding rubber on the valve shaft  33  made of stainless steel. One will appreciate that other suitable materials may be used. 
         [0044]    For convenience in explanation and accurate definition in the appended claims, the terms “up” or “upper”, “down” or “lower”, “front” or “rear”, “inside”, and etc. may be used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
         [0045]    The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.