Abstract:
An air intake apparatus for an internal combustion engine includes an intake manifold adapted for being connected to an engine head, the intake manifold including therein an intake passage through which a stream of fuel-air mixture passes and a receiving portion formed at an inner circumferential surface of the intake passage, the receiving portion being at a downstream side of stream of fuel-air mixture; a valve open/close mechanism including a cartridge made of resin, an open/close valve accommodated in the cartridge, and a shaft for rotating the open/close valve, the cartridge defining a first clearance with the receiving portion and defining a second clearance with the engine head; and a first elastic member arranged between the engine head and the cartridge of the valve opening/closing mechanism for elastically retaining the cartridge in an upstream direction of the stream of fuel-air mixture.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 U.S.C. §119 to Japanese Patent Application 2008-162961, filed on Jun. 23, 2008, the entire content of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to an air intake apparatus for an internal combustion engine. 
     BACKGROUND 
     From a perspective of a weight reduction of a petrol engine for a vehicle and from a perspective of increases of thermal insulating properties and design flexibility of the petrol engine, an intake manifold distributing air sucked by the engine into cylinders has been mainly made of resin instead of metal such as aluminum alloy in recent years. However, when a resin is applied as a material of the intake manifold, the form accuracy tends to deteriorate because warpage or shrinkage of the resin is unavoidable, compared to an intake manifold made of metal. 
     For example, a four-cylinder engine includes an intake manifold having four air intake passages. Further, the air intake manifold includes an air intake apparatus controlling an air intake volume and a flow rate or direction of air sucked into the air intake passages when needed. The air intake apparatus includes open/close valves opened and closed by a shaft in the respective air intake passages in accordance with rotation of the shaft. Opening of the open/close valve is controlled by an actuator so that an appropriate combustion condition is obtained depending on driving states of a vehicle. 
     For example, an air intake apparatus for an internal combustion engine described in JP2006-233907A (hereinafter referred to as Patent document 1) includes a plurality of resin control units serving as a valve opening/closing mechanism. Each of the control units is arranged in a receiving portion of an intake manifold attached to a cylinder head, thereby opening and closing each air intake passage of the intake manifold. The control unit includes a housing (cartridge) and an open/close valve rotatably supported in the housing. The housing of the control unit is inserted in the receiving portion of the intake manifold while having a predetermined clearance defined between an outer surface of the housing and the receiving portion. Accordingly, the housing is retained to the intake manifold via elastic members. 
     However, according to the Patent document 1, when the intake manifold is expanded due to heat or deformed due to a dimensional change caused by water absorption, the housing of the control unit is deformed via the elastic members. Accordingly, the housing may be cracked and damaged due to stress generated by the deformation of the control unit. When the housing is deformed, scoring or scratches of the open/close valve arranged in the housing occurs, so hat a bearing of the shaft is not precisely aligned to a desired position. Consequently, when the open/close valve is opened and closed by the shaft in accordance with the rotation of the shaft, a slide resistance of the open/close valve and abrasions of the bearing may incase. Moreover, when a clearance between the housing and the open/close valve is increased, a seal performance of the open/close valve may deteriorate when the open/close valve is in a fully closed state. 
     In addition, when the cylinder head and the housing make contact with each other, stress is generated in the housing. Accordingly, the housing may be cracked and damaged. Additionally, when a clearance for preventing the stress is established between the cylinder head and the housing, the housing is moved in the clearance during an activation of the engine. As a result, an abnormal noise may occur and durability of the control unit may deteriorate. 
     A need thus exists for an air intake apparatus for an internal combustion engine, which is not susceptible to the drawback mentioned above. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the present invention, an air intake apparatus for an internal combustion engine includes an intake manifold adapted for being connected to an engine head, the intake manifold including therein an intake passage through which a stream of fuel-air mixture passes and a receiving portion formed at an inner circumferential surface of the intake passage, the receiving portion being at a downstream side of the stream of fuel-air mixture; a valve open/close mechanism including a cartridge made of resin, an open/close valve accommodated in the cartridge, and a shaft for rotating the open/close valve, the cartridge defining a first clearance with the receiving portion and defining a second clearance with the engine head; and a first elastic member arranged between the engine head and the cartridge of the valve opening/closing mechanism for elastically retaining the cartridge in an upstream direction of the stream of fuel-air mixture. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description considered with the reference to the accompanying drawings, wherein: 
         FIG. 1  is an enlarged cross-sectional view of an air intake apparatus for an internal combustion engine according to a first embodiment of the present invention; 
         FIG. 2  is an enlarged cross-sectional view of an air intake apparatus for an internal combustion engine according to a second embodiment of the present invention; and 
         FIG. 3  is an enlarged cross-sectional view of an air intake apparatus for an internal combustion engine according to a third embodiment of the present invention. 
         FIG. 4  is an enlarged cross-sectional view of an air intake apparatus for an internal combustion engine according to a fourth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention will be explained with reference to the illustrations of the figures as follows.  FIG. 1  is an exploded cross-sectional view of an air intake apparatus  1  for an internal combustion engine according to a first embodiment. The air intake apparatus  1  includes a valve opening/closing mechanism  10 , an intake manifold  20 , and an elastic member (fist elastic member)  30 . The valve opening/closing mechanism  10  is arranged within the intake manifold  20 . Further, the valve opening/closing mechanism  10  includes a cartridge  11  made of resin, an open/close valve  12  arranged within the cartridge  11 , and a shaft  13  rotating the open/close valve  12  to open and close. The cartridge  11  includes a flange  14 . The intake manifold  20  is attached to an engine head  2  with a fastening member such as a bolt. The intake manifold  20  includes an air intake passage  21  and a receiving portion  22 . The intake manifold  20  is attached to the engine head  2 . The intake manifold  20  includes the receiving portion  22  in an inner circumferential surface of the air intake passage  21  in a downstream direction of a flow of air sucked into the air intake passage  21  of the intake manifold  20 . The elastic member  30  is arranged between the engine head  2  and the cartridge  11  of the valve opening/closing mechanism  10 . The elastic member  30  elastically retains the flange  14  of the cartridge  11  in an upstream direction of the flow of the sucked air in the air intake passage  21  of the intake manifold  20 . An approximately  1 -millimeter clearance (first clearance)  24  is established between an outer circumferential surface  15  of the cartridge  11  and an inner circumferential surface  23  of the receiving portion  22 . An approximately 3-millimeter clearance (second clearance)  25  is established between the engine head  2  and the flange  14 . 
     When an engine is activated, air for combustion of the engine is sucked into the intake manifold  20  and flows from the upstream direction to the downstream direction of the sucked air in the air intake passage  21 . At this time, the shaft  13  is rotated in response to a signal transmitted from an engine control unit, thereby opening and closing the open/close valve  12  of the valve opening/closing mechanism  10 . Accordingly, the flow of the sucked air is controlled. The intake manifold  20  and the engine head  2  are deformed due to thermal expansion or the like in accordance with the activation (combustion) of the engine. However, the deformation of the intake manifold  20  is tolerated by means of the clearance  24 . In addition, the deformation of the engine head  2  is tolerated by the elastic member  30  arranged in the clearance  25 . Accordingly, the valve opening/closing mechanism  10  is free from being deformed. 
     In the air intake apparatus  1  of the first embodiment, the clearance  24  by which the deformation of the intake manifold  20  is tolerated, is arranged between the outer circumferential surface  15  of the cartridge  11  and the inner circumferential surface  23  of the receiving portion  22 . Further, the clearance  25  is arranged between the engine head  2  and the flange  14 . The flange  14  is elastically retained by the elastic member  30  in the upstream direction of the flow of the sucked air in the air intake passage  21 , so that the deformation of the intake manifold  20  is tolerated by means of the clearance  24 . Accordingly, a clearance  16  defined between the cartridge  11  and the open/close valve  12  and a bearing  17  of the shaft  13  are not affected by the deformation of the intake manifold  20 . Consequently, scoring or scratches of the open/close valve  12  is prevented. Further, a slide resistance of the shaft  13  opening and closing the open/close valve  12  and abrasions of the bearing  17  of the shaft  13  are prevented from increasing. Thus, an appropriate seal performance of the open/close valve  12  is obtained when the open/close valve  12  is opened and closed. In addition, the deformation of the engine head  2  is tolerated by an elastic force of the elastic member  30  arranged in the clearance  25 , so that the flange  14  does not make contact with the engine head  2 . Accordingly, an excessive stress is prevented from acting on the flange  14 . Consequently, the flange  14  is prevented from being cracked and damaged. Moreover, the flange  14  is elastically retained in the upstream direction of the flow of the sucked air in the air intake passage  21 , thereby being prevented from moving in the clearance  25  during the activation of the engine. Consequently, the occurrence of an abnormal noise during the activation of the engine is reduced. As a result, the endurance of the valve opening/closing mechanism  10  is prevented from deteriorating. 
       FIG. 2  is an enlarged cross-sectional view of an air intake apparatus  40  for the internal combustion engine according to a second embodiment. In the second embodiment, same numbers are assigned to members having similar portions and functions similar to those of the first embodiment. A main different configuration and effects due to the configuration will be described as follows. 
     The air intake apparatus  40  according to the second embodiment is different from the air intake apparatus  1  of the first embodiment in that an elastic member (second elastic member)  42  is arranged between the flange  14  of a valve opening/closing mechanism  41  and the intake manifold  20 . The elastic member  42  elastically retains the flange  14  in the downstream direction of the flow of the sucked air in the air intake passage  21 . Other configurations are the same as the configurations of the valve opening/closing mechanism  10  of the first embodiment. 
     In addition to the effects of the first embodiment, both surfaces (located in the upstream and downstream directions of the flow of the sucked air in the air intake passage  21 ) of the flange  14  are elastically retained by the elastic member  30  and the elastic member  42  in the air intake apparatus  40 . Accordingly, even when the engine head  2  and the intake manifold  20  are deformed, the deformation does not affect the valve opening/closing mechanism  41  because the elastic member  30  is arranged between the engine head  2  and the cartridge  11  and the elastic member  42  is arranged between the intake manifold  20  and the cartridge  11 . Consequently, an operational failure of the valve opening/closing mechanism  41  may be prevented. 
       FIG. 3  is an enlarged cross-sectional view of an air intake apparatus  50  for the internal combustion engine according to a third embodiment. In the third embodiment, same numbers are assigned to members having similar portions and functions to those of the first embodiment. A main different configuration and effects according to the configuration will be described as follows. 
     The air intake apparatus  50  according to the third embodiment is different from the air intake apparatus  1  of the first embodiment in that a an annular groove  53  is formed in a flange  52  of a valve opening/closing mechanism  51  in the air intake apparatus  50  and that the elastic member  30  in the form of an O-ring are arranged in the groove  53 . Other configurations are the same as the configurations of the valve opening/closing mechanism  10  of the first embodiment. The groove  53  is opposition to the engine head  2 . The elastic member or O-ring  30  is larger than the groove  53  in width such that when the elastic member  30  is fitted in the groove  53  the elastic member  30  is under compression and protrudes from the groove  53  to be in fluid-tight engagement with the engine head  2 . 
     The air intake apparatus  50  according to the third embodiment is different from the air intake apparatus  1  of the first embodiment in that a an annular groove  53  is formed in a flange  52  of a valve opening/closing mechanism  51  in the air intake apparatus  50  and that the elastic member  30  in the form of an O-ring are arranged in the groove  53 . Other configurations are the same as the configurations of the valve opening/closing mechanism  10  of the first embodiment. The groove  53  is opposition to the engine head  2 . The elastic member or O-ring  30  is larger than the groove  53  in width such that when the elastic member  30  is fitted in the groove  53  the elastic member  30  is under compression and protrudes from the groove  53  to be in fluid-tight engagement with the engine head  2 . 
     In addition to the effects of the first embodiment, the deformation of the elastic member  30  in the width direction (vertical direction as seen in  FIG. 3 ) is limited by the groove  53 . Accordingly, an elastic force of the elastic member  30  in the downstream direction of the flow of the sucked air in the air intake passage  21  increases, so that the elastic member  30  is effectively compressed. In addition, when the intake manifold  20  is assembled on the engine head  2 , the elastic member  30  is prevented from protruding from the groove  53  of the flange  52 . Accordingly, an increase of a flow resistance of the sucked air in the intake manifold  20  due to the assembling failure between the intake manifold  20  and the engine head  2  and the protrusion of the elastic member  30  from the groove  53  of the flange  52  is reduced. 
     Although the case where the elastic member  30  is arranged in the groove  53  formed in the flange  52  is described in the third embodiment, a groove may be arranged in a surface of the flange  52 , which located in the upstream direction of the flow of the sucked air in the air intake passage  21 . 
     The air intake apparatus  60  according to the fourth embodiment illustrated in  FIG. 4  includes a second elastic member  42  arranged between a flange  52  of a valve opening/closing mechanism  61  and the intake manifold  20 , and an annular groove  53  formed in the flange  52  in which the elastic member  30  is arranged. 
     As described in the aforementioned embodiments, the deformation of the intake manifold  20  is tolerated by means of the clearance  24 , thereby not affecting the clearance  16  between the cartridge  11  and the open/close valve  12  and the bearing  17  of the shaft  13 . Accordingly, when the open/close valve  12  is opened and closed in accordance with rotation of the shaft  13 , a slide resistance of the shaft  13  and abrasions of the bearing  17  of the shaft  13  are prevented from increasing. Consequently, an appropriate seal performance of the open/close valve  12  is obtained when the open/close valve  12  is in a fully closed state. Moreover, the deformation of the engine head  2  is tolerated by an elastic force of the elastic member  30 , so that the engine head  2  and the cartridge  11  do not make contact with each other. Further, an excessive stress due to the deformation of the engine head  2  is prevented from acting on the cartridge  11 . Consequently, the occurrence of cracks and damage of the cartridge  11  is prevented. In addition, since the cartridge  11  is elastically retained by the elastic member  30  in the upstream direction of the sucked air in the air intake passage  21 , the cartridge  11  is prevented from moving in the clearance  25  during the activation of the engine. Thus, the occurrence of an abnormal noise is prevented and the durability of the valve opening/closing mechanism  10 ,  41 ,  51  may be prevented from deteriorating. 
     According to the aforementioned embodiments, the cartridge  11  includes the flange  14 ,  52  and the second clearance  25  is established between the engine head  2  and the flange  14 ,  52 . Moreover, the first elastic member  30  elastically retains the flange  14 ,  52  in the upstream direction of the flow of the sucked air in the air intake passage  21 . 
     Accordingly, the engine head  2  and the flange  14 ,  52  do not make contact with each other, so that an excessive stress due to the deformation of the engine head  2  is prevented from acting on the flange  14 ,  52 . Consequently, the occurrence of cracks and damage of the flange  14 ,  52  may be prevented. Moreover, the flange  14 ,  52  is prevented from moving in the clearance  25  during the activation of the engine. As a result, the occurrence of an abnormal noise is reduced, so that the durability of the valve opening/closing mechanism  10 ,  41 ,  51  may be prevented from deteriorating. 
     According to the aforementioned embodiments, the second elastic member  42  is arranged between the flange  14  and the intake manifold  20 . The second elastic member  42  elastically retains the flange  14  in the downstream direction of the flow of the sucked air in the air intake passage  21 . 
     Accordingly, the both surfaces (located in the upstream and downstream directions of the flow of the sucked air in the air intake passage  21 ) of the flange  14  are elastically retained by the elastic member  30  and the elastic member  42 . Even when the engine head  2  and the intake manifold  20  are deformed, the above-mentioned deformation does not affect the valve opening/closing mechanism  41  because the elastic member  30  is arranged between the engine head  2  and the cartridge  11  and the elastic member  42  is arranged between the intake manifold  20  and the cartridge  11 . Consequently, the operating failure of the valve opening/closing mechanism  41  may be prevented. 
     According to the aforementioned embodiments, the groove  53  is formed in the flange  52 , and at least one of the first elastic member  30  and the second elastic member  42  is arranged in the groove  53  of the flange  52 . 
     Accordingly, the deformation of the elastic member  30  or the elastic member  42  in the width direction is limited by the groove  53 . Consequently, an elastic force in the downstream direction or the upstream direction of the sucked air in the air intake passage  21  increases, compared to the case where the elastic member  30  is arranged on a surface of the flange  14 . As a result, the elastic member  30  or the elastic member  42  may be effectively compressed. In addition, when the intake manifold  20  is assembled on the engine head  2 , the elastic member  30  or the elastic member  42  may be prevented from protruding from the groove  53  of the flange  52 . Thus, an increase of a flow resistance of the sucked air in the air intake passage  21  due to the assembling failure between the engine head  2  and the intake manifold  20  and the protrusion of the elastic member  30  or the elastic member  42  from the groove  53  of the flange  52  is reduced. 
     The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.