Abstract:
An air intake control system is provided for an internal combustion engine of a vehicle. The control system includes an intake port of a cylinder head for an engine main body, a throttle body having a throttle valve and connected to the intake port, an electric actuator having an electric motor and arranged on the throttle body to drive open or close the throttle valve, and a connector disposed on a housing of the electric actuator in a position facing toward one axial end of a crankshaft. The connector is provided in order to connect to an outside conductor to the electric motor of the electric actuator. The resulting configuration facilitates the work to connecting the outside conductor to the connector.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2006-269405, filed Sep. 29, 2006, the entire contents of which are hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to an air intake control system (electronic throttle, DBW) for an internal Combustion engine of a vehicle, in which a throttle body having a throttle valve is connected to an intake port of a cylinder head which an engine main body is provided with, and an electric actuator having an electric motor is arranged on the throttle body to drive open or close the throttle valve. 
         [0004]    2. Description of Background Art 
         [0005]    An air intake control system in which an electronic actuator having an electric motor is mounted on a throttle body to drive open or close a throttle valve is already known, for example, from Japanese Patent No. 3536612, for example. 
         [0006]    A connector is arranged on a housing of an electric actuator to connect an outside conductor to an electric motor which an electric actuator is provided with. It is, hence, desired to permit easy connecting work of the outside connector to the connector in a state that a throttle body has been assembled on an internal combustion engine. In Japanese Patent No. 3536612 referred to in the above, however, no consideration is made about the arrangement of a connector and no disclosure is found about the arrangement of a connector. 
         [0007]    With the foregoing circumstances in view, the present invention has as an object thereof the provision of an air intake control system for an internal Combustion engine of a vehicle, which facilitates connecting work of an outside conductor to a connector of an electric actuator arranged on a throttle body. 
       SUMMARY AND OBJECTS OF THE INVENTION 
       [0008]    To achieve the above-described object, according to a first aspect of the invention, in an air intake control system for an internal Combustion engine of a vehicle, said system including an intake port of a cylinder head which an engine main body is provided with, a throttle body having a throttle valve and connected to the intake port, and an electric actuator having an electric motor and arranged on the throttle body to drive open or close the throttle valve, a connector disposed on a housing of the electric actuator to connect an outside conductor to the electric motor is arranged facing toward one axial end of a crankshaft. 
         [0009]    According to a second aspect of the invention, the engine main body is mounted on a body frame with a cylinder axis inclined forwardly and upwardly or rearwardly and upwardly along an advancing direction of the vehicle, and the throttle body is arranged lower than a top end of a head cover connected to the cylinder head. 
         [0010]    According to a third aspect of the invention, a direction of the connector is set substantially in parallel with a bottom wall of an air cleaner arranged above the electric actuator. 
         [0011]    According to a fourth aspect of the invention, the connector is disposed on the housing as a common connector for at least the electric motor and a sensor for detecting an opening of the throttle. 
         [0012]    The effects of the invention include the following: 
         [0013]    According to the first aspect of the invention, the connector of the electric actuator is directed toward the one axial end of the crankshaft. Therefore, upon performing connecting work of the outside conductor to the connector, the engine main body does not lie in the way so that the connecting work is facilitated and wiring is also facilitated. 
         [0014]    According to the second aspect of the invention, it is possible to arrange the throttle body at as low a position as possible so that the entire internal combustion engine can be constructed in a compact size. 
         [0015]    According to the third aspect of the invention, the outer conductor to be connected to the connector can be arranged at a position close to the air cleaner without any interference with the air cleaner and also in close proximity with the side of the engine main body, thereby contributing to an overall size reduction of the internal combustion engine. 
         [0016]    According to the fourth aspect of the invention, a single common connector is used for plural electric parts including at least the electric motor and the sensor. Compared with the use of plural connectors, it is possible to decrease the number of parts, and hence to achieve a cost reduction and to facilitate the wiring. 
         [0017]    Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
           [0019]      FIG. 1  is a side view of a motorcycle; 
           [0020]      FIG. 2  is a cross-sectional view taken along line  2 - 2  of  FIG. 1 ; 
           [0021]      FIG. 3  is a vertical cross-sectional side view of an engine main body; 
           [0022]      FIG. 4  is vertical cross-sectional view of a hydraulic valve-deactivating mechanism; 
           [0023]      FIG. 5  is a perspective view of a pin holder as viewed from above; 
           [0024]      FIG. 6  is a perspective view of a pin holder as viewed from below; 
           [0025]      FIG. 7  is a perspective view of a slide pin; 
           [0026]      FIG. 8  is a transverse cross-sectional view of a throttle body on a side of a front bank; 
           [0027]      FIG. 9  is a transverse cross-sectional view of a throttle body on a side of a rear bank; and 
           [0028]      FIG. 10  is a vertical cross-sectional side view of an engine main body in a second example. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]      FIG. 1  through  FIG. 9  show a first embodiment of the invention. 
         [0030]    Referring first to  FIG. 1 , through a head pipe  11  which a body frame F of a motorcycle as a vehicle is provided with at a forward thereof, a front fork  12  with a front wheel WF rotatably supported thereon is steerably used. A steering bar  13  is connected to an upper part of the front fork  12 . Further, a rear fork  14  with a rear wheel WR rotatably supported thereon is supported rockably up and down on the body frame F. This rear fork  14  is suspended from the body frame F via a suspension means  15 . 
         [0031]    On the vehicle frame F between the front wheel WF and the rear wheel WR, an internal combustion engine EA—which is, for example, a four-cylinder V-type internal combustion engine—and a power unit P including an unillustrated transmission are mounted. To an output shaft  16  of the power unit P, the rear wheel WR is interlockingly connected via a chain transmission mechanism  17 . 
         [0032]    With reference to  FIG. 2 , the body frame F has a pair of main frames  18 , 18  parting right and left from the head pipe  11  and extending rearwardly and downwardly. These main frames  18 , 18  are curved such that they bulge out in right and left directions, respectively. An engine main body  19  of the internal combustion engine EA is disposed between the main frames  18 , 18 , and a rider&#39;s seat  20  is mounted on the body frame F such that the rider&#39;s seat is arranged rearward and above the engine main body  19 . 
         [0033]    Referring also to  FIG. 3 , the engine main body  19  is constructed as a V-type with a front bank BF and rear bank BR that form a substantially V-shape. The front and rear banks BF, BR are each provided with two cylinders arranged side by side in a direction transverse to the vehicle frame F. Lower parts of the front bank BF and rear bank BR are commonly connected to a crankcase  22  which rotatably supports a crankshaft  21  having a horizontal axis line extending at right angles to an advancing direction of the motorcycle. 
         [0034]    The front bank BF is equipped with a cylinder block  24 F defining therein a pair of cylinder bores  23 F,  23 F having a cylinder axis line CF inclined forwardly and upwardly, a cylinder head  25 F connected to the cylinder block  24 F, and a head cover  26 F connected to the cylinder head  25 F, while the rear bank BR is equipped with a cylinder block  24 R defining therein a pair of cylinder bores  23 R,  23 R having a cylinder axis line CR inclined rearwardly and upwardly, a cylinder head  25 R connected to the cylinder block  24 R, and a head cover  26 R connected to the cylinder head  25 R. Further, pistons  27  slidably fitted in the respective cylinder bores  23 F,  23 F,  23 R,  23 R of the front and rear banks BF,BR are commonly connected to the crankshaft  21  via connecting rods  28 , respectively. 
         [0035]    As illustrated in  FIG. 2 , a distance LF between the respective cylinder bores  23 F,  23 F in the front bank BF is, therefore, set greater than a distance LR between the respective cylinder bores  23 R,  23 R in the rear bank BR. 
         [0036]    Between the cylinder blocks  24 F,  24 R and the cylinder heads  25 F,  25 R in the front and rear banks BF, BR, combustion chambers  29  are formed corresponding to the respective cylinders such that head portions of the corresponding pistons  27  face the combustion chambers, respectively. Through the cylinder head  25 F of the front bank BF, intake ports  31 F and exhaust ports  32 F are formed such that they can be brought into communication with the corresponding combustion chambers  29 . The intake ports  31 F open in a rear side wall of the cylinder head  25 F such that they face a V-shaped space formed between the front bank BF and the rear bank BR, while the exhaust ports  32 F open in a front side wall of the cylinder head  25 F. Through the cylinder head  25 R of the rear bank BR, on the other hand, the intake ports  3   1 R and exhaust ports  32 R are formed such that they can be brought into communication with the corresponding combustion chambers  29 . The intake ports  31 R open in a front side wall of the cylinder head  25 R such that they face the V-shaped space, while the exhaust ports  32 R open in a rear wall of the cylinder head  25 R. 
         [0037]    Between the cylinder head  25 F and head cover  26 F in the front bank BF, a valve actuator  35 F is accommodated to drive open or close intake valves  33 F and exhaust valves  34 F arranged corresponding to the respective cylinders in the cylinder head  25 F such that the intake valves and exhaust valves can be operated open or close. Between the cylinder head  25 R and head cover  26 R in the rear bank BR, on the other hand, a valve actuator  35 R is accommodated to drive open or close intake valves  33 R and exhaust valves  34 R arranged corresponding to the respective cylinders in the cylinder head  25 R such that the intake valves and exhaust valves can be operated open or close. 
         [0038]    The valve actuators  35 F,  35 R are, therefore, provided with camshafts  36 ,  36  to which rotary power is transmitted at a reduction ratio of 1/2 from the crankshaft  21  via corresponding unillustrated timing transmitting devices; valve lifters  38  interposed between intake-side valve cams  37  arranged on the camshafts  36 ,  36  and the intake valves  33 F,  33 F,  33 R,  33 R and slidably fitted in the cylinder heads  25 F,  25 R, respectively; and rocker arms  40  arranged between exhaust-side valve cams  39  disposed on the camshaft  36 ,  36  and exhaust valves  34 F,  34 F,  34 R,  34 R such that the rocker arms  40  can be rocked by exhaust-side valve cams  39 , respectively. 
         [0039]    It is to be noted that the valve actuator  35 F for all the cylinders in the front bank BF is constructed to operate full time during an operation of the engine while the valve actuator  35 R for all the cylinders in the rear bank BR is constructed to be able to take a cylinder-deactivating state. 
         [0040]    In  FIG. 4 , the valve actuator  35 R in the rear bank BR is provided with a hydraulic valve-deactivating mechanism  43 . This hydraulic valve-deactivating mechanism  43  is equipped with a pin holder  44  slidably fitted in a valve lifter  38 , a slide pin  46  forming a hydraulic chamber  45  between itself and an inner wall of the valve lifter  38  and slidably fitted in the pin holder  44 , a return spring  47  arranged between the slide pin  46  and the pin holder  44  to produce spring force that biases the slide pin  46  in a direction to reduce the volume of the hydraulic chamber  45 , and a stopper pin  48  arranged between the pin holder  44  and the slide pin  46  to prevent the slide pin  46  from turning about its axis line. 
         [0041]    Referring to  FIG. 5  and  FIG. 6  in combination, the pin holder  44  is integrally equipped with a ring portion  44   a  slidably fitted in the valve lifer  38  and a bridge portion  44   b  connecting together diametrically-opposite two points on an inner circumference of the ring portion  44   a  along one diametric line. Between the inner circumference of the ring portion  44   a  and respective side walls of the bridge portion  44   b , excess metal is cut away to achieve a weight reduction. 
         [0042]    On an outer circumference of the pin holder  44 , specifically on an outer circumference of the ring portion  44   a , an annular groove  49  is formed. Formed through the bridge portion  44   b  of the pin holder  44  is a bottomed slide hole  50 , which has an axis line extending along the one diametric line of the ring portion  44   a , in other words, extending at right angles to an axis line of the valve lifter  38 , is open at one end thereof in the annular groove  49 , and is closed at an opposite end thereof. The bridge portion  44   b  is provided at a central lower part thereof with an insertion opening  52  such that its inner end opens in the slide hole  50 . The insertion opening  52  allows a free end portion of a valve stem  51  of an intake valve  33 R to extend therethrough when the intake valve  33 R is biased in a valve-closing direction by a valve spring  42 . In a central upper part of the bridge portion  44   b , on the other hand, an extension hole  53  with the slide hole  50  located between itself and the insertion hole  52  is formed coaxially with the insertion hole  52  such that the extension hole  53  can accommodate the free end portion of the valve stem  51  of the intake valve  33 R. 
         [0043]    At a part facing a closed end of the valve lifter  38 , the bridge portion  44   b  of the pin holder  44  is integrally provided with a receiving cylindrical portion  54  which is coaxial with an axis line of the extension hole  53 , and a portion of a disk-shaped shim  55 , which closes an end portion of the extension hole  53  on the side of the closed end of the valve lifter  38 , is fitted in the receiving cylindrical portion  54 . Moreover, the inner wall of the closed end of the valve lifter  38  is integrally provided at a central part thereof with a raised portion  56  which is in contact with the shim  55 . 
         [0044]    The slide pin  46  is slidably fitted in the slide hole  50  of the pin holder  44 . Between an end of the slide pin  46  and the inner wall of the valve lifter  38 , the hydraulic chamber  45  is formed in communication with the annular groove  49 . The return spring  47  is accommodated in a spring chamber  57  formed between the other end of the slide pin  46  and the closed end of the slide hole  50 . 
         [0045]    Also referring to  FIG. 7 , the slide pin  46  is provided in an axial intermediate portion thereof with a receiving hole  58  such that the receiving hole  58  can receive the free end portion of the valve stem  51 . This receiving hole  58  can extend coaxially with the insertion opening  52  and extension hole  53 . An end portion of the receiving hole  58  on the side of the insertion opening  52  opens in a flat contact wall  59 , which is formed on an outer wall of a lower portion of the slide pin  46  at a location opposite the insertion opening  52 . Accordingly, the contact wall  59  is formed relatively long along the direction of an axis line of the slide pin  46 , and the receiving hole  58  opens in the contact wall  59  at a part located on the side of the spring chamber  57 . 
         [0046]    The slide pin  46  constructed as described above axially slides such that the hydraulic force acting on the side of one end of the slide pin  46  under the hydraulic pressure in the hydraulic chamber  45  and the spring force acting on the side of the other end of the slide pin  46  by the return spring  47  balance each other. At the time of non-operation that the hydraulic pressure of the hydraulic chamber  45  is low, the slide pin  46  moves rightward as viewed in  FIG. 4  so that the free end portion of the valve stem  51 , which has inserted into the insertion opening  52 , is received in the receiving hole  58  and extension hole  53 . In an operation state that the hydraulic pressure of the hydraulic chamber  45  has arisen to a high pressure, on the other hand, the slide pin  46  moves leftward as viewed in  FIG. 4  such that the axis line of the receiving hole  58  is bought into a misalignment with those of the insertion opening  52  and extension hole  53  and the free end of the valve stem  51  is brought into contact with the contact wall  59 . 
         [0047]    When the slide pin  46  has moved to the position where the receiving hole  58  extends coaxially with the insertion opening  52  and extension hole  53 , the pin holder  44  and slide pin  46  also move together with the valve lifter  38  toward the intake valve in response to sliding of the valve lifter  38  under pressing force acting on the intake-side valve cam  37 . This, however, simply results in the reception of the free end portion of the valve stem  51  in the receiving hole  58  and extension hole  53 , and no pressing force acts in the valve-opening direction on the intake valve  33 R from the valve lifter  38  and pin holder  44  so that the intake valve  33 R remains deactivated. When the slide pin  46  has moved to the position where its contact wall  59  comes into contact with the free end portion of the valve stem  51 , on the other hand, pressing force acts in the valve-opening direction on the intake valve  33 R as a result of a movement of the pin holder  44  and slide pin  46  toward the intake valve  33 R in response to sliding of the valve lifter  38  under pressing force acting from the intake-side valve cam  37 . The intake valve  33 R is, therefore, operated open or close responsive to rotation of the intake-side valve cam  37 . 
         [0048]    When the slide pin  46  turns about its axis line within the pin holder  44 , a misalignment takes place between the axis line of the receiving hole  58  and those of the insertion opening  52  and extension hole  53 , and further, it becomes impossible to bring the free end portion of the valve stem  51  into contact with the contact wall  59 . The slide pin  46  is, therefore, prevented from turning about its axis line by the stopper pin  48 . 
         [0049]    The stopper pin  48  is fixed in fixing bores  60  arranged coaxially in the bridge portion  44   b  of the pin holder  44  such that the slide hole  50  is located at one end portion thereof between the fixing bores  60 . The stopper pin  48  extends through a slit  61  formed on one end of the slide pin  46  such that the slit  61  opens toward the hydraulic chamber  45 . The stopper pin  48  is, therefore, fixed on the pin holder  44  such that it extends through the slide pin  46  while allowing the sliding pin  46  to move in the direction of its axis line. By a contact of the stopper pin  48  with a closed inner end portion of the slit  61 , the slide pin  46  is also limited from moving toward the hydraulic chamber  45 . 
         [0050]    A coil spring  62 , which biases the pin holder  44  toward the side that the shim  55  fixed on the pin holder  44  is brought into contact with the raised portion  56  arranged on the central part of the inner wall of the closed end of the valve lifter  38 , is arranged between the pin holder  44  and the cylinder head  25 R such that the coil spring  62  surrounds the valve stem  51  at a position where an outer circumference of the coil spring  62  is prevented from coming into contact with the inner wall of the valve lifter  38 . On the bridge portion  44   b  of the pin holder  44 , a pair of ridges  63 , 63  are integrally arranged to position an upper end portion of the coil spring  62  in a direction perpendicular to the axis line of the valve stem  51 . 
         [0051]    Moreover, both of the ridges  63 ,  63  are integrally arranged on the pin holder  44  with an extent of protrusion not greater than the wire diameter of the coil spring  62 , and are formed in the shape of circular arcs centering about the axis line of the valve stem  51 . 
         [0052]    On one of the ridges  63 ,  63 , a stepped portion  63 a is formed such that the stepped portion  63 a comes into contact with an end portion of the stopper pin  48 , said end portion being on the side of the intake valve  33 R, to prevent the stopper pin  48  from moving toward the intake valve  33 R. 
         [0053]    The slide pin  46  is provided with a communication hole  64 , which keeps the spring chamber  57  in communication with the receiving hole  58  to prevent pressurization or depressurization of the spring chamber  57  by a movement of the slide pin  46  in the axial direction thereof. The pin holder  44  is provided with a communication hole  65 , which keeps the above-described space in communication with the spring chamber  57  to prevent the pressure in the space between the pin holder  44  and the valve lifter  38  from varying by a change in temperature. 
         [0054]    The cylinder head  25 R is provided with a support bore  66  in which the valve lifter  38  is fitted to slidably support the valve lifter  38 . On an inner wall of the support bore  66 , an annular recess  67  is formed surrounding the valve lifter  38 . The valve lifter  38 , on the other hand, is provided with a communication hole  68 , which maintains the annular recess  67  in communication with the annular groove  49  of the pin holder  44  irrespective sliding movements of the valve lifter  38  in the support bore  66 . The valve lifter  38  is also provided with a release hole  69 . This release hole  69  is formed through the valve lifter  38  at such a position that, when the valve lifter  38  has moved to a highest level as shown in  FIG. 4 , the release hole  69  brings the annular recess  67  into communication with the inside of the valve lifter  38  at a level lower than the pin holder  44  but the communication with the annular recess  67  is cut off as the valve lifter  38  moves downward from the highest level depicted in  FIG. 4 . Through this release hole  69 , working oil is injected into the valve lifter  38 . 
         [0055]    Referring back to  FIG. 3  again, throttle bodies  71 F,  71 F are connected to the intake ports  32 F,  32 F in the cylinder head  25 F of the front bank BF, respectively; throttle bodies  71 R,  71 R are connected to the intake ports  32 R,  32 R in the cylinder head  25 R of the rear bank BR, respectively; and the respective throttle bodies  71 F,  71 F,  71 R,  71 F are provided with fuel injection valves  72  to inject fuel toward the intake ports  32 F,  32 F,  32 R,  32 R, respectively. The throttle bodies  71 F,  71 F on the side of the front bank BF and the throttle bodies  71 R,  71 R on the side of the rear bank BR are commonly connected to an air cleaner  73  arranged above the throttle bodies  71 F,  71 F,  71 R,  71 R. 
         [0056]    In  FIG. 8 , throttle valves  74 ,  74  in the two throttle bodies  71 F,  71 F on the side of the front bank BF are rotationally controlled together, because valve shafts  75 ,  75  on which these throttle valves  74 ,  74  are fixed are connected together by a connecting member  76 . A single electric actuator AF, which is common to both of the throttle bodies  71 F,  71 F, is fixed on one of the throttle bodies  71 F,  71 F. 
         [0057]    This electric actuator AF is constructed of an electric motor  77  having a axis line of rotation perpendicular to the valve shaft  75 , a drive pinion  79  arranged on an output shaft  78  of the electric motor  77 , a large-diameter intermediate gear  80  arranged in meshing engagement with the drive pinion  79 , a small-diameter intermediate gear  81  rotatable integrally with the large-diameter intermediate gear  80 , and a driven sector gear  82  fixed on the valve shaft  75  and arranged in meshing engagement with the small-diameter intermediate gear  81 . A housing  83  which accommodates the electric actuator AF is constructed of a housing-forming section  84  integral with the throttle body  71 F and a cover member  85  made of a synthetic resin and connected to the housing-forming section  84 . 
         [0058]    In addition, a return spring  86  is arranged between the throttle body  71 F and the driven sector gear  82  in the housing  83 . The return spring  86  exhibits spring force in a direction that the throttle valves  74  are returned to the full-close positions, respectively. On the cover member  85 , a sensor  87  for detecting a rotated position of the valve shaft  75 , in other words, an opening of the throttle valve  74  is attached such that the sensor  87  faces an end face of the valve shaft  75 . 
         [0059]    In  FIG. 9 , the throttle bodies  71 R,  71 R on the side of the rear bank BR are individually provided with electric actuators AR, AR to control cylinder by cylinder the amount of air intake. Moreover, the throttle bodies  71 R,  71 R and electric actuators AR, AR have the same constructions as the throttle bodies  71 F,  71 F on the side of the front bank BF and the electric actuator AF, respectively. Therefore, elements corresponding to the throttle bodies  71 F,  71 F and electric actuator AF on the side of the front bank BF are illustrated only in the figure by applying the same reference numerals to the corresponding elements, and their detailed description is omitted. 
         [0060]    The cover members  85 ,  85 ,  85  in the housings  83 ,  83 ,  83  of the respective electric actuators AF, AR, AR are provided with connectors  88 ,  88 ,  88  to connect outside conductors to at least the electric motors  77 ,  77 ,  77 , respectively. In this example, the connectors  88 ,  88 ,  88 , which are common to the electric motors  77 ,  77 ,  77  and the sensors  87 , 87 , 87 , respectively, are arranged on the cover members  85 , 85 , 85  so that outside conductors can be connected to them, respectively. As shown clearly in  FIG. 3 , these connectors  88 ,  88 ,  88  are arranged such that they are located above the engine main body  19 , are directed toward an axial one end of the crankshaft  21 , and lie substantially in parallel with the bottom wall  73   a  of the air cleaner  73  disposed above the electric actuators AF, AR, AR. 
         [0061]    A description will next be made about the operation of the first example. The connectors  88 ,  88 ,  88  disposed on the housings  83 ,  83 ,  83  of the respective electric actuators AF, AR, AR—which are fixed on the throttle bodies  71 F,  71 F,  71 R,  71 R connected to the respective intake ports  32 F,  32 F,  32 R,  32 R in the cylinder heads  25 F,  25 R which the front and rear banks BF, BR in the engine main body  19  are provided with—are arranged to face the axial one end of the crankshaft  21 . Therefore, upon performing connecting work of the outside conductors to the connectors  88 ,  88 ,  88 , the engine main body  19  does not lie in the way so that the connecting work can be facilitated and the wiring can also be facilitated. 
         [0062]    Moreover, the directions of the connectors  88 ,  88 ,  88  are set substantially in parallel with the bottom wall  73   a  of the air cleaner  73  arranged above the electric actuators AF, AR, AR. The outer conductors to be connected to the respective connectors  88 ,  88 ,  88  can be arranged at a position close to the air cleaner  73  without any interference with the air cleaner  73  and also in close proximity with the side of the engine main body  19 , thereby contributing to an overall size reduction of the internal combustion engine EA. 
         [0063]    The connectors  88 ,  88 ,  88  are disposed on the housings  83 ,  83 ,  83  commonly for at least the corresponding electric motors  77 ,  77 ,  77  and sensors  87 ,  87 ,  87  for detecting openings of the respective throttle valves  74 ,  74 ,  74 . Compared with the use of plural connectors on each housing, it is possible to decrease the number of parts, and hence to achieve a cost reduction and to facilitate the wiring. 
         [0064]    Furthermore, the valve actuators  35 F for all the cylinders in the front bank BF are constructed to operate full time during operation of the engine, while the valve actuators  35 R for all the cylinders in the rear bank BR can be brought into a cylinder-deactivated state. Upon deactivating some of the plural cylinders, the cylinders in the front bank BF, which are readily exposed to running wind, are controlled to operate full time. It is, therefore, possible to improve the cooling efficiency of the internal combustion engine EA. 
         [0065]    A second example of the present invention will hereinafter be described with reference to  FIG. 10 . An engine main body  91  of an inline multicylinder, for example, four-cylinder internal combustion engine EB is provided with a crankcase  92 , a cylinder block  94  defining four cylinder bores  93  arranged side by side and connected to the crankcase  92 , a cylinder head  95  connected to the cylinder block  94 , and a head cover  96  connected to the cylinder head  95 , and a cylinder axis line C of each cylinder bore  93  is inclined forwardly and upwardly. 
         [0066]    Between the cylinder block  95  and the head cover  96 , combustion chambers  98  are formed corresponding to the respective cylinders such that head portions of corresponding pistons  97  slidably fitted in the cylinder bores  93  face the combustion chambers  98 , respectively. Through the cylinder head  95 , intake ports  99  and exhaust ports  100  are formed corresponding to the respective cylinders such that they can be brought into communication with the corresponding combustion chambers  98 . The intake ports  99  open in a rear side wall of the cylinder head  95 , while the exhaust ports  100  open in a front side wall of the cylinder head  95 . 
         [0067]    Between the cylinder head  95  and the head cover  96 , a valve actuator  103  is accommodated to drive open or close intake valves  101  and exhaust valves  102  arranged corresponding to the respective cylinders such that the intake valves  101  and exhaust valves  102  can be operated open or close. The valve actuator  103  is provided with an intake-side camshaft  105  and exhaust-side camshaft  106  to which rotary power is transmitted at a reduction ratio of  1 / 2  from the crankshaft  104  rotatably supported in the crankcase  92  via an unillustrated timing transmitting device; valve lifters  108  interposed between intake-side valve cams  107  arranged on the intake-side camshaft  105  and the intake valves  101  and slidably fitted in the cylinder head  95 ; and exhaust-side valve lifters  110  interposed between exhaust-side cams  109  arranged on the exhaust-side camshaft  106  and the exhaust valves  102  and slidably fitted in the cylinder head  95 . 
         [0068]    Further, the valve actuator  103  is also provided at its parts—which among the inline four cylinders, correspond to both end cylinders along the array direction of the cylinders—with similar hydraulic valve-deactivating mechanisms (not shown) as the hydraulic valve-deactivating mechanism  43  described with reference of  FIG. 4  to  FIG. 7  of the first embodiment, and the both end cylinders along the array direction of the cylinders can be brought into a cylinder-deactivated state by closing and deactivating the intake valves  101 . 
         [0069]    Throttle bodies  71  are connected to the intake ports  99  in the cylinder head  95 ; and the respective throttle bodies  71  are provided with fuel injection valves  72  to inject fuel toward the intake ports  99 , respectively. The throttle bodies are commonly connected to an air cleaner  111  arranged above the throttle bodies  71 . 
         [0070]    Connectors  88  are disposed on housings  83  of electric actuators A fixed on the respective throttle bodies  71 , an these connectors  8  are arranged above the engine main body  91  and facing toward an axial one end of the crankshaft  104 . The directions of the connectors  88  are set substantially in parallel with a bottom wall  11  la of the air cleaner  111  arranged above the electric actuators A, and moreover, the throttle bodies  71  are arranged lower than a top end of the head cover  96 . 
         [0071]    Similar to the first example described above, the second example can also avoid lying of the engine main body in the way upon performing connecting work of outside conductors to the connectors  88 , so that the connecting work can be facilitated and wiring can also be facilitated. The outer conductors to be connected to the connectors  88  can be arranged at positions close to the air cleaner  111  without any interference with the air cleaner  111  and also in close proximity with the side of the engine main body  91 , thereby making it possible to contribute to a size reduction of the internal combustion engine EB. In addition, the entire internal combustion engine EB can be constructed in a compact size by arranging the throttle bodies  71  at as low positions as possible. 
         [0072]    As a further example of the present invention, the throttle bodies  71 F,  71 R of the first example as depicted in  FIG. 1  through  FIG. 9  may be arranged lower than top ends of the head covers  26 F,  26 R in the respective banks BF, BR. This arrangement makes it possible to arrange the throttle bodies at as low positions as possible and hence to construct the entire internal combustion engine EA in a compact size. Especially with a V-shaped internal combustion engine EA, the throttle bodies  71 F,  71 R can be effectively arranged in the space between the banks BF and BR to construct the internal combustion engine EA in a compact size. 
         [0073]    The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.