Abstract:
An intake control valve of an intake device of an internal combustion engine comprises a given portion defined by an air intake passage that leads to a combustion chamber of the engine through an intake valve; a pivot shaft passing through the given portion; and a valve plate secured to the pivot shaft to pivot therewith within the given portion. The valve plate is pivotal between a close position to close the air intake passage and an open position to open the air intake passage. When the valve plate assumes the close position, the interior of the air intake passage downstream the valve plate is formed with mutually isolated first and second air flows that are separated and oriented to enhance a flow of air/fuel mixture in the combustion chamber.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates in general to intake devices of an internal combustion engine and more particularly to intake devices of a type that comprises an intake control valve installed in an intake tube of each cylinder of the engine. More specifically, the present invention is concerned with the intake device of such type that enhances a gas flow in each combustion chamber. 
         [0003]    2. Description of the Related Art 
         [0004]    As is known, for improving combustion of an internal combustion engine, more specifically, for assuring a stable combustion of a lean air/fuel mixture, it is effective to enhance a gas flow in the-combustion chamber. Swirling and tumbling effects are those that enhance the gas flow in the combustion chamber. 
         [0005]    One of intake devices of an internal combustion engine that enhances such gas flow is disclosed by Japanese Laid-open Patent Application (Tokkai) 2004-124835. In the device disclosed by the publication, a passage is provided which extends from a diametrically one part of a downstream portion of an intake port to the diametrically other part of an upstream portion of the same where a larger intake air flow is needed. With this, part of the intake air flowing along the one part of the intake port is forcedly led to the upstream other part of the same thereby to enhance the gas flow in the combustion chamber. Actually, with this measure, the tumbling effect is increased or enhanced. 
       SUMMARY OF THE INVENTION 
       [0006]    However, the measure of the publication sometimes brings about an unexpected phenomenon. That is, at the side of the intake port where part of the intake air is taken or sucked, a smaller intake air flow is inevitably carried out along the intake port. However, such smaller intake air flow tends to induce a backflow of a residual gas in the cylinder back into the intake port. The residual gas may reach the intake control valve because of creation of a lower pressure area at a portion downstream the intake control valve, which causes the intake control valve and its surrounding area to have carbon particles deposited thereon. Of course, in such case, a satisfied intake air control is not expected by the intake control valve. 
         [0007]    Accordingly, it is an object of the present invention to provide an intake device of an internal combustion engine, which is free of the above-mentioned drawbacks. 
         [0008]    According to the present invention, there is provided an intake device of an internal combustion engine, which exhibits not only enhancement of gas flow in the combustion chamber by an intake control valve but also suppression of the undesired backflow of a residual gas into the intake port. 
         [0009]    In accordance with a first aspect of the present invention, there is provided an intake device of an internal combustion engine, which comprises an air intake passage leading to a combustion chamber of the engine through an intake valve; a fuel injection valve provided in the air intake passage to inject a fuel into the air intake passage; and an intake control valve arranged in the air intake passage at a position upstream of the fuel injection valve, wherein the intake control valve comprises a given portion defined by the air intake passage a pivot shaft passing through the given portion; a valve plate secured to the pivot shaft to pivot therewith within the given portion, the valve plate being pivotal between a close position to close the air intake passage and an open position to open the air intake passage; and an arrangement that provides, when the valve plate assumes the close position, the interior of the air intake passage downstream the valve plate with mutually isolated first and second air flows that are separated and oriented to enhance a flow of air/fuel mixture in the combustion chamber. 
         [0010]    In accordance with a second aspect of the present invention, there is provided an intake device of an internal combustion engine, which comprises an air intake passage leading to a combustion chamber of the engine through an intake valve; a fuel injection valve provided in the air intake passage to inject a fuel into the air intake passage; a throttle valve installed in the air intake passage upstream of the fuel injection valve to control the amount of air led to the combustion chamber; a control unit that controls operation of the fuel injection valve and the throttle valve in accordance with an operation condition of the engine; and an intake control valve arranged in the air intake passage between the throttle valve and the fuel injection valve, wherein the intake control valve comprises a rectangular parallelepiped given portion defined by the air intake passage; a pivot shaft passing through the given portion, the pivot shaft being controlled by the control unit; a rectangular valve plate secured to the pivot shaft to pivot therewith within the given portion, the rectangular valve plate being pivotal between a close position to close the air intake passage and an open position to open the air intake passage; and an upper side open portion that is provided when the valve plate assumes the close position, the upper side open portion being a given cut formed in an upper right half portion of the valve plate; and a lower side open portion that is provided when the valve plate assumes the close position, the lower side open portion being an open portion provided at an opposite position of the given cut with respect to an axial center line of the air intake passage, wherein a flow passage sectional area of the lower side open portion is smaller than that of the upper side open portion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Other objects and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings, in which: 
           [0012]      FIG. 1  is a diagrammatic system view of an internal combustion engine to which the present invention is practically applied; 
           [0013]      FIG. 2A  is a schematically illustrated intake device of a first embodiment of the present invention under a condition wherein an intake control valve is closed; 
           [0014]      FIG. 2B  is a schematic view taken from the direction of an arrow “Y” of  FIG. 2A ; 
           [0015]      FIG. 2C  is a sectional view taken along the line “Z-Z” of  FIG. 2B , showing an arrangement of a pivot shaft to which a valve plate of the intake control valve is secured; 
           [0016]      FIG. 2D  is a view similar to  FIG. 2C , but showing a modification of the arrangement of the pivot shaft; 
           [0017]      FIG. 3  is a view similar to  FIG. 1 , but showing advantageous operation of the intake device of the first embodiment of the present invention; 
           [0018]      FIGS. 4A to 4D  are views similar to  FIG. 2B , but showing first, second, third and fourth modifications of the intake device of the first embodiment of the present invention; 
           [0019]      FIGS. 5A to 5E  are views also similar to  FIG. 2B , but showing fifth, sixth, seventh, eighth and ninth modifications of the intake device of the first embodiment of the present invention; 
           [0020]      FIG. 6A  is a view similar to  FIG. 2A , but showing an intake device of a second embodiment of the present invention; 
           [0021]      FIG. 6B  is a view similar to  FIG. 6A , but showing advantageous operation of the intake device of the second embodiment of the present invention; and 
           [0022]      FIG. 7  is a view similar to  FIG. 6A , but showing a modification of the intake device of the second embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0023]    In the following, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
         [0024]    For ease of understanding, various directional terms, such as upper, lower, right, left, upward and the like are used in the description. However, such terms are to be understood with respect to only a drawing or drawings on which a corresponding part or portion is shown. Furthermore, throughout the description, substantially same parts or elements are denoted by the same numerals. 
         [0025]    Referring to  FIG. 1 , there is schematically shown an internal combustion engine to which a first embodiment of the present invention is practically applied. 
         [0026]    In the drawing, denoted by numeral  1  is an internal combustion engine. Under operation of the engine  1 , air is led into an air cleaner  2  to be cleaned. Air is then led to an electronically controlled throttle valve  4 . Before reaching throttle valve  4 , a flow rate of air is measured by an air flow meter  3 . As will be described in detail hereinafter, a flow rate of air led to the engine  1  is controlled by throttle valve  4 . Air is then led to each intake tube  6  through an intake collector  5 . Each intake tube  6  has an electronically controlled fuel injection valve  7  from which a fuel is injected to mix with the air to form an air/fuel mixture that is led into a combustion chamber  9  through an intake valve  8 . 
         [0027]    Upon reaching combustion chamber  9 , the air/fuel mixture is ignited by an ignition plug  10  and burnt. A combustion gas (viz., exhaust gas) thus produced in combustion chamber  9  is discharged to an exhaust passage  12  through an exhaust valve  11 . Thereafter, the exhaust gas is purified by an exhaust gas purifying device, viz., catalytic converter (not shown), mounted in exhaust passage  12  and discharged to open air. 
         [0028]    As shown, each intake tube  6  is provided with an intake control valve ICV at a position upstream fuel injection valve  7 . Intake control valve ICV is of a so-called flap type that comprises a pivot shaft  14  that is rotatably held by a lower wall portion of intake tube  6  and a valve plate  13  that is fixed at its lower end to pivot shaft  14  to pivot therewith. That is, by controlling the angle of the valve plate  13 , the flow passage area of intake tube  6  can be adjusted. 
         [0029]    It is to be noted that pivot shaft  14  is a common shaft that extends along an axis of the engine  1  and has a plurality of valve plates  13 , for respective intake tubes  6 , fixed thereto. Thus, in case of a four cylinder inline engine, four valve plates  13  are mounted to the common shaft  14  to pivot therewith. 
         [0030]    As is understood from  FIG. 2B , valve plate  13  is rectangular in shape and thus a given portion of intake tube  6  where valve plate  13  is pivotally received has a rectangular cross section. That is, the given portion has a rectangular parallelepiped shape. 
         [0031]    As is seen from  FIG. 2B , the rectangular valve plate  13  is formed at its upper right half portion with a rectangular cut  61  which serves as an upper side open portion  61  as will be described in detail hereinafter. It is to be noted that  FIG. 2B  is a view taken from the direction of the arrow “Y” of  FIG. 2A . 
         [0032]    Furthermore, as is seen from  FIGS. 2B and 2C , upon assemblage of intake control valve ICV in the rectangular parallelepiped given portion of intake tube  6 , an elongate clearance  62  is formed or defined between pivot shaft  14  and a bottom wall of the given portion of intake tube  6 . As is understood from  FIGS. 2B and 2C , the bottom wall is formed with a rounded groove that extends along pivot shaft  14  to provide the elongate clearance  62  that has a thickness of “g”. As will be described in detail hereinafter, the elongate clearance  62  serves as a lower side open portion  62 . 
         [0033]    It is now to be noted that as is seen from  FIG. 2A , when intake control valve ICV is in its full-close position, the upper side open portion  61  is positioned above an axial center line “X” of intake tube  6 , and the lower side open portion  62  is positioned below the axial center line “X”. It is further to be noted that when intake control valve ICV is in its full-open position, the rectangular valve plate  13  is neatly received in a recess  63  formed in a lower wall part of intake tube  6 . 
         [0034]    Referring to  FIG. 2D , there is shown a modification  62 ′ of the lower side open portion  62 . In this modification  62 ′, pivot shaft  14  is formed thereabout with at least one groove that constitutes the lower side open portion  62 . 
         [0035]    It is to be noted that the upper side open portion  61  functions to enhance a flow of the air/fuel mixture in combustion chamber  9 . Basically, the position and size of the upper side open portion  61  are varied for each engine. However, it has been revealed that for the enhanced gas flow in combustion chamber  9 , it is preferable to position the open portion  61  at a right upper or left upper portion of the rectangular parallelepiped given portion of intake tube  6 . 
         [0036]    It is further to be noted that the lower side open portion  62  functions to suppress or at least minimize undesired backflow of a residual gas in the cylinder back into intake tube  6  and creation of a lower pressure area at a portion downstream of intake control valve ICV when intake control valve ICV is in its closed position. 
         [0037]    Experiments and simulation carried out by the inventors have revealed that when the area of the lower side open portion  62  is about 20 to 25% of that of the upper side open portion  61 , the above-mentioned two functions show a satisfied level. 
         [0038]    Referring back to  FIG. 1 , an engine control unit ECU  20  is arranged which electronically controls throttle valve  4 , intake control valve ICV, fuel injection valve  7  and ignition plug  10  in accordance with an operation condition of engine  1  and other conditions. 
         [0039]    For such controlling, various information signals are fed to engine control unit ECU  20 , which are for example a signal from air flow meter  3  that represents an amount “Qa” of intake air, a signal from an accelerator open degree sensor (not shown) that represents an open (or depressed) degree “APO” of an accelerator pedal (not shown), a signal from a crank angle sensor (not shown) that represents an engine rotation speed “Ne” and a signal from a temperature sensor (not shown) that represents a temperature “Tw” of an engine cooling water. 
         [0040]    In the following, operation of the intake device of the present invention will be described with the aid of the accompanying drawings, especially  FIGS. 1 ,  2 A to  2 C and  3 . 
         [0041]    When the engine  1  is under a low speed low load operation condition, engine control unit ECU  20  controls intake control valve ICV to take the full-close position as is shown in  FIG. 3 . 
         [0042]    Under this condition, for the reasons as mentioned hereinabove, the upper side open portion  61  and the lower side open portion  62  are provided by valve plate  13  and pivot shaft  14  respectively. Accordingly, as is seen from  FIG. 3 , during flow, the intake air is divided into upper and lower flows “A” and “B” that run through the upper and lower side open portions  61  and  62  respectively. 
         [0043]    As is described hereinabove, the area of the lower side open portion  62  is about 20 to 25% of that of the upper side open portion  61 , and thus, most of the intake air is forced to run through the upper side open portion  61  as is indicated by the arrow “A”. The intake air running through the opening  61  is accelerated and rushed into combustion chamber  9  with a certain inlet angle relative to the chamber  9  together with the injected fuel from fuel injection valve  7  (see  FIG. 1 ). With this action, enhanced swirling and tumbling effects of intake air are produced in combustion chamber  9 . 
         [0044]    While, part of the intake air runs through the lower side open portion  62  as is indicated by the arrow “B”. As is seen from the drawing of  FIG. 3 , the intake air run in the direction of arrow “B” opposes a backflow of a residual gas from the cylinder  9  as indicated by an arrow “C”, and thus the backflow of the residual gas is suppressed or at least minimized. Furthermore, at the same time, creation of undesired lower pressure area “D” at the portion downstream of intake control valve ICV is suppressed or at least minimized. 
         [0045]    Accordingly, a combustion stability of the engine  1  under a low speed low load operation is improved especially when the engine  1  is operated on a lean air/fuel mixture. Furthermore, the undesired backflow of a residual gas, which would occur when intake control valve ICV is in its close position, is suppressed or at least minimized by the air flow that has passed through the lower side open portion  62 . This means that intake control valve ICV and its surrounding area are prevented from being deposited by carbon particles. Thus, a stable intake air control is assured for a long time by intake control valve ICV. 
         [0046]    Furthermore, due to the measures mentioned hereinabove, generation of vortex of air in intake tube  6  at a position downstream intake control device ICV is minimized, which suppresses undesired backflow of the residual gas from combustion chamber  9  of engine  1  back into intake tube  6 . 
         [0047]    As has been mentioned hereinabove, in place of the lower side open portion  62  shown by  FIG. 2C , the modification  62 ′ shown in  FIG. 2D  is usable in the invention. That is, in this modification  62 ′, the groove formed about pivot shaft  14  serves as the lower side open portion  62 , and thus substantially same effect is obtained from such modification  62 ′. 
         [0048]    Referring to  FIGS. 4A ,  4 B,  4 C and  4 D, there are shown first, second, third and fourth modifications ICV- 1 , ICV- 2 , ICV- 3  and ICV- 4  of the intake control valve ICV, which are also usable in the intake device of the first embodiment of the present invention. 
         [0049]    As is seen from  FIG. 4A , in first modification ICV- 1 , the upper side open portion  61  is the same as that shown by  FIG. 2B  of the above-mentioned first embodiment. While, in this first modification ICV- 1 , the lower side open portion  62   a  is a half of the above-mentioned elongate clearance  62  in length. That is, the portion  62   a  is provided at a lower left half of valve plate  13 . More specifically, such half-sized clearance  62   a  is produced by providing a left half of the bottom wall of the rectangular parallelepiped given portion of intake tube  6  with a rounded groove. The half-sized clearance  62   a  is shown to have a thickness “g1”. In this first modification ICV- 1 , a possible undesirable phenomenon wherein due to positioning of the upper side open portion  61  at the right position, the power of backflow of the residual gas into intake tube  6  is inevitably increased is suppressed or at least minimized. If desired, the half-sized clearance  62   a  may be provided by forming a round recess about pivot shaft  14 . 
         [0050]    As is seen from  FIG. 4B , in second modification ICV- 2 , the upper side open portion  61  is the same as that of the above-mentioned first modification ICV- 1 . While, in this second modification ICV- 2 , the lower side open portion  62   b  is defined by providing a lower left wall of the rectangular parallelepiped given portion of intake tube  6  with a shallow recess. The recess is shown to have a thickness “g2”. If desired, as is indicated by a broken line in  FIG. 4B , the left wall of the rectangular parallelepiped given portion may be formed with an elongate recess  62   b ′ for the lower side open portion, that extends between upper and lower walls of the given portion as shown. 
         [0051]    Furthermore, if desired, in place of the recess  62   b , valve plate  13  may be provided at a left lower portion thereof with a cut  62  for producing the lower side open portion, as is shown in  FIG. 4C . This is the third modification ICV- 3  of the intake control valve ICV. 
         [0052]    As is seen from  FIG. 4D , in fourth modification ICV- 4  of the intake control valve ICV, an opening  62   d  is formed in a lower left portion of valve plate  13  for producing the lower side open portion  62   d.    
         [0053]    Referring to  FIGS. 5A ,  5 B,  5 C,  5 D and  5 E, there are shown fifth, sixth, seventh, eighth and ninth modifications ICV- 5 , ICV- 6 , ICV- 7 , ICV- 8  and ICV- 9  of the intake control valve ICV, which are also usable in the intake device of the first embodiment of the present invention. 
         [0054]    As is seen from these drawings, the fifth to ninth modifications ICV- 5 , ICV- 6 , ICV- 7 , ICV- 8  and ICV- 9  are of a so-called butterfly type that comprises a pivot shaft  14  that is rotatably held by a vertically middle portion of the rectangular parallelepiped given portion of intake tube  6  and a valve plate  13  that is fixed at its middle portion to pivot shaft  14  to pivot therewith. 
         [0055]    As is seen from  FIG. 5A , in fifth modification ICV- 5 , the upper side open portion  61  is the same as that shown by  FIG. 2B . While, in this fifth modification ICV- 5 , the lower side open portion is a portion  62   e  that is defined or provided between the lower end of valve plate  13  and the bottom wall of the rectangular parallelepiped given portion of intake tube  6  as shown. The lower side open portion  62   e  is shown to have a thickness of “g3” in the drawing. As is understood from the drawing, if pivot shaft  14  is arranged at a vertically middle portion of the given portion of intake tube  6 , fixing of valve plate  13  to pivot shaft  14  is so made that the length “L1” from the upper end of valve plate  13  to an axis of pivot shaft  14  is greater than “L2” from the lower end of valve plate  13  to the axis of pivot shaft  14  by a degree of the thickness “g3”. With this, such lower side open portion  62   e  is provided. 
         [0056]    As is seen from  FIG. 5B , in sixth modification ICV- 6 , the lower side open portion  62   f  is a shorter cut that is formed in a lower left part of valve plate  13 . More specifically, the open portion  62   f  extends from the left end of valve plate  13  to a laterally middle portion of the same, as shown. 
         [0057]    As is seen from  FIG. 5C , in seventh modification ICV- 7 , the lower side open portion  62   g  is defined by providing a lower left wall of the given portion of intake tube  6  with a shallow recess, like the above-mentioned second modification ICV- 2  of  FIG. 4B . 
         [0058]    As is seen form  FIG. 5D , in eighth modification ICV- 8 , the lower side open portion  62   h  is defined by a small cut  62   h  provided at the left lower portion of valve plate  13 , like the above-mentioned third modification ICV- 3  of  FIG. 4C . 
         [0059]    As is seen from  FIG. 5E , in ninth modification ICV- 9 , the lower side open portion  62 i is defined by a small opening  62 i formed in the left lower portion of valve plate  13 , like the above-mentioned fourth modification ICV- 4  of  FIG. 4D . 
         [0060]    For the reasons as mentioned hereinabove, also in these first to ninth modifications ICV- 1  to ICV- 9  of intake control valve ICV, enhanced swirling and tumbling effects of intake air are expected in combustion chamber  9 , and a combustion stability of the engine  1  under a low speed low load operation is improved especially when the engine  1  is operated on a lean air/fuel mixture. Of course, the undesired backflow of a residual gas, which would occur when intake control valve is in its close position, is suppressed or at least minimized. This means that intake control valve and its surrounding area are prevented from being deposited by carbon particles, and thus, a stable intake air control is assured for a long time by the intake control valve. 
         [0061]    In the following, an intake device of a second embodiment of the present invention will be described with reference to the accompanying drawings. 
         [0062]    Referring to  FIG. 6A , there is shown an intake device of the second embodiment which is similar to that of the above-mentioned first embodiment of  FIG. 2A . 
         [0063]    As is seen from the drawing ( FIG. 6A ), the intake device of the second embodiment is substantially the same as that of the above-mentioned first embodiment of  FIG. 2A  except that in the second embodiment a curved partition wall  15  is provided in intake tube  6  at a position downstream the intake control valve ICV. Partition wall  15  has opposed side ends fixed to diametrically opposed portions of intake tube  6  respectively, and thus the intake passage downstream of intake control valve ICV is divided into upper and lower passages  6   a  and  6   b  as shown. As shown, partition wall  15  has an axially extending middle portion that extends on and along the axial center line “X” of intake tube  6 . 
         [0064]    It is to be noted that as is seen from  FIG. 6A , when intake control valve ICV is in its full-close position, the upper side open portion  61  is positioned above the axial center line “X” of intake tube  6 , and the lower side open portion  62  is positioned below the axial center line “X”. It is further to be noted that when intake control valve ICV is in its full-open position, the rectangular valve plate  13  is neatly received in the recess  63  formed in the lower wall part of intake tube  6 . 
         [0065]    Due to provision of partition wall  15 , the following advantage is further obtained in addition to the advantages possessed by the first embodiment, which will be described with reference to  FIG. 6B  in the following. 
         [0066]    That is, as is seen from  FIG. 6B , due to partition wall  15  by which upper and lower passages  6   a  and  6   b  are defined, the upper flow “A” of intake air that has passed through the upper side open portion  61  is forced to flow in only the upper passage  6   a  as is indicated by thick arrows. Thus, the upper intake air flow “A” is much accelerated and rushed into combustion chamber  9  with a much sharper inlet angle relative to the chamber  9  together with the injected fuel from fuel injection valve  7  (see  FIG. 1 ). Thus, the swirling and tumbling effects of intake air in combustion chamber  9  is much enhanced. Furthermore, as is seen from the drawing ( FIG. 6B ), the undesired backflow of a residual gas, which would occur when intake control valve ICV assumes its close position as shown, is suppressed or at least minimized by the air flow that has passed through the lower side open portion  62 . This means that intake control valve ICV and its surrounding area are prevented from being deposited by carbon particles and thus a stable intake air control is assured for a long time by intake control valve ICV. 
         [0067]    Referring to  FIG. 7 , there is shown a modification of the intake device of the second embodiment. 
         [0068]    As is understood from the drawing, in this modification, a smaller intake control valve ICV- 10  is used. More specifically, the valve plate  13 ′ employed by the intake control valve ICV- 10  is a smaller rectangular plate that is sized to close only the lower passage  6   b  when assuming its close position, as shown. That is, when intake control valve ICVB- 10  is in its close position as shown in the drawing, the upper passage  6   a  serves as the upper side open portion  61 , and the clearance between pivot shaft  14  and the bottom wall of the rectangular parallelepiped given portion of intake tube  6  serves as the lower side open portion  62 . Also in this modification, substantially same advantageous effects as those of the above-mentioned second embodiment of  FIG. 6A  are obtained. 
         [0069]    The entire contents of Japanese Patent Application 2006-102896 filed Apr. 4, 2006 are incorporated herein by reference. 
         [0070]    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.