MXPA06008552A - Engine - Google Patents

Abstract

An engine, wherein an intake valve openably driven by an intake side valve system having an intake side camshaft and an exhaust valve openably driven by an exhaust side valve system having an exhaust side camshaft are disposed in a cylinder head forming a part of an engine body. The intake side camshaft (30) is disposed at a position such that the distance thereof from a combustion chamber (17) is larger than that in the case of the exhaust side camshaft (35) along the axis (C) of the cylinder of the engine body (11) to position the intake side camshaft higher than the exhaust side camshaft (35). Thus, the exhaust side valve system can be efficiently lubricated and cooled by easily using a lubricating oil, used for lubricating and cooling the intake side valve system, for the exhaust side valve system.

Description

MOTOR FIELD OF THE INVENTION The present invention relates to an engine in w an intake valve driven by opening and closing operations is provided by an intake valve operation device having an intake camshaft and an exhaust valve driven for opening and closing operations by an exhaust valve operating device having an exhaust camshaft in a cylinder head forming a portion of a motor body.

TECHNICAL BACKGROUND Such an engine is known from Document 1 of Patent, for example. Patent Document 1: Japanese Patent Application Laid-Open No. 2004-52708.

DESCRIPTION OF THE INVENTION PROBLEM TO BE RESOLVED BY THE INVENTION The lubrication and cooling of an exhaust valve operation device must be performed under thermally severe conditions as compared to the lubrication and cooling of an intake valve operation device. If lubricating oil can be used for an exhaust valve operating device after it is used for lubrication and cooling of an intake valve operation device at a comparatively low temperature, lubrication and cooling of the exhaust valve operating device perform efficiently. In the engine described in Japanese Patent Application Laid-Open above No. 2004-52708, however, the intake camshaft of the intake valve operation device and the exhaust camshaft of the operation device of Exhaust valve are placed in the same position in the direction along the cylinder axis of the engine body and, therefore, it is difficult to use lubricating oil for the lubrication and cooling of the exhaust valve operation device after using it for the lubrication of the intake camshaft. In view of the circumstances described above, it is an object of the present invention to provide a motor in w the lubricating oil can be easily used for an exhaust valve operation device after it is used to lubricate and cool an operating device. of intake valve to allow lubrication and cooling of exhaust valve operation device with efficiency. To achieve the above-described object, according to a first feature of the present invention, there is provided an engine having a cylinder head that forms a portion of a motor body and is provided with an impulse intake valve for opening operations and closing by means of an intake valve operation device having an intake camshaft and an exhaust valve operated for opening and closing operations by an intake valve operation device having an exhaust camshaft, characterized because the intake camshaft is placed in a higher position than the exhaust camshaft by increasing the distance between the intake camshaft and a combustion chamber along a cylinder axis of the engine body with relationship to the distance between the exhaust camshaft and the combustion chamber. According to a second feature of the present invention in addition to the arrangement of the first feature, a motor is provided, wherein the intake valve operation device has a variable lift mechanism capable of changing the amount of opening elevation of the valve. valve of the intake valve, and the exhaust valve operation device has the exhaust camshaft and an exhaust rocker arm linked and connected to the exhaust valve to oscillate by pushing the exhaust camshaft. According to a third feature of the present invention in addition to the arrangement of the first feature, a motor is provided, wherein the motor body is positioned in such a position that the cylinder axis is inclined towards the exhaust valve operating device. According to a fourth feature of the present invention in addition to the arrangement of the first feature, a motor is provided, wherein the direction of rotation of the intake camshaft is set so that the intake camshaft rotates as it moves towards up on the side where the intake camshaft confronts the exhaust valve operation device. According to a fifth feature of the present invention in addition to the disposition of the second feature, there is provided an engine, wherein the intake valve operation device includes the intake camshaft having a valve operating cam. admission, an intake rocker arm having a cam contact portion contacting the intake valve operation cam, the rocker arm is linked and connected to the intake valve to apply a force to the intake valve. admission in the valve opening direction, and the variable lift mechanism, and the variable lift mechanism has a first link arm having one end thereof rotatably connected to the arm of the inlet rocker arm and the other end supported on rotating shape in a fixed position in the motor body through a fixed support shaft, and a second articulation arm which has one end thereof connected in a rotatable manner to the arm of the intake rocker and the other end supported rotatably in a mobile support shaft that is capable of traveling. According to a sixth feature of the present invention in addition to the arrangement according to the fifth feature, a motor is provided, wherein the fixed support shaft and the mobile support shaft are placed within a portion for connection and connection from the rocker arm for intake valve to the intake valve, and a portion of the exhaust valve operating device for oscillatingly supporting the rocker arm that is placed outside a portion for connection and connection of the rocker arm of exhaust and the exhaust valve.

According to a seventh feature of the present invention in addition to the arrangement according to the sixth feature, an engine is provided, wherein a spark plug cylinder inclined to get closer to the exhaust valve operation device in a closer position an upper end thereof is mounted on the cylinder head when placed between the intake valve operating device and the exhaust valve operating device.

EFFECT OF THE INVENTION According to the first characteristic of the present invention, the intake camshaft is higher in its position than the exhaust camshaft. Therefore, the lubricating oil can easily flow into the exhaust valve operating device after lubricating and cooling the intake valve operation device to a comparatively low temperature, thereby achieving efficient lubrication and cooling of the intake device. Exhaust valve operation under thermally severe conditions. According to the second feature of the present invention, the elevation of the intake valve is changed by the variable lift mechanism, thereby enabling the control of the amount of air intake without using the throttle valve. In addition, the variable lift mechanism can be effectively arranged in a space on the side of the intake valve operating device where there is a larger space than on the side of the exhaust valve operating device. According to the third feature of the present invention, the cylinder shaft of the motor body is inclined towards the exhaust valve operating device, so that the lubricating oil flows more smoothly towards the exhaust valve operation device afterwards. of lubricating and cooling the intake valve operation device, thereby achieving more efficient lubrication and cooling of the exhaust valve operating device. According to the fourth feature of the present invention, an upward splash of the lubricating oil towards the exhaust valve operating device is caused by rotation of the intake camshaft to more efficiently lubricate and cool the valve operation device. escape. According to the fifth characteristic of the present invention, the ends of the first and second articulation arms forming the variable elevation mechanism are connected rotary directly to the rocker arm, in such a way that the space in which they are disposed. two articulation arms is reduced, thereby making the intake valve operation device compact. Since the driving power is transmitted directly from the intake valve operation cam to the cam contact portion of the intake rocker arm, improved fluidity can be ensured towards the valve operating cam. According to the sixth feature of the present invention, the fixed support shaft and the mobile support shaft of the first and second articulation arms are placed within a portion for connection and connection of the intake rocker arm and the valve inlet, and a portion of the exhaust valve operating device for oscillatingly supporting the exhaust rocker arm that is positioned outside a portion for attachment and connection of the exhaust rocker arm and the exhaust valve. Therefore, it is possible to avoid mutual interference between the intake valve operating device and the exhaust valve operating device while preventing an increase in the size of the cylinder head even in a case where the angle contained between the intake valve and the outlet valve is small. According to the seventh characteristic of the present invention, the spark plug cylinder is positioned to avoid interference with the intake valve operation device and the exhaust valve operating device. This placement contributes to the effect of making the entire cylinder head more compact.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a partial longitudinal sectional view of an engine according to an embodiment of the present invention taken along line 1-1 of FIGURE 2 (Mode 1). FIGURE 2 is a sectional view taken along line 2-2 of FIGURE 1 (Modality 1). FIGURE 3 is a sectional view taken along line 3-3 of FIGURE 2 (Modality 1). FIGURE 4 is an elongated view of an essential portion of FIGURE 1 (Modality 1). FIGURE 5 is a bottom view of an inlet rocker arm seen in the direction of arrow 5 in FIGURE 4 (Mode 1). FIGURE 6 is a sectional view taken along line 6-6 of FIGURE 4 (Modality 1). FIGURE 7 is a perspective view of a variable lifting mechanism (Modality 1). FIGURE 8 is a sectional view taken along line 8-8 of FIGURE 4 (Modality 1). FIGURE 9 is a sectional view taken along line 9-9 of FIGURE 2 (Modality 1). FIGURE 10 is a perspective view seen in the direction of arrow 10 in FIGURE 9 (Modality 1).

DESCRIPTION OF NUMBERS AND REFERENCE CHARACTERISTICS 11 engine body 14 cylinder head 17 combustion chamber 20 intake valve 21 exhaust valve 28 intake valve operation device 29 intake valve operation cam 31 intake arm 32 variable lift mechanism 33 exhaust valve operation device 34 exhaust valve operation cam 35 exhaust camshaft 36 exhaust rocker arm 37 rotation direction 39 intake cam 43 exhaust rocker arm shaft 50 roller as a cam contact portion 57 inlet rocker shaft as a fixed support shaft 58 first articulation arm 59 second articulation arm 60 mobile support axle 87 spark plug cylinder C cylinder shaft E engine BEST MODE FOR CARRYING OUT THE INVENTION A mode for carrying out the present invention will be described by means of an embodiment of the present invention with reference to the accompanying drawings.

MODE 1 FIGURES 1 to 10 show one embodiment of the present invention. Referring to FIGURE 1, a motor body 11 of an in-line multiple cylinder E engine comprises a cylinder block 13 in which cylinder bores 12 are provided, a cylinder head 14 attached to an upper face of the block 13. of cylinders, and a head cover 15 attached to an upper face of the cylinder head 14. Pistons 16 are slidably fitted in the cylinder bores 12. The combustion chambers 17 confronting the upper parts of the pistons 16 are formed between the cylinder block 13 and the cylinder head 14. The cylinder head 14 is equipped with intake ports 18 and exhaust ports 19 which can communicate with the combustion chambers 17. Each of the intake ports 18 is opened and closed by a pair of intake valves 20 while each of the exhaust ports 19 is opened and closed by a pair of exhaust valves 21. Valve springs 23 are provided to bias the intake valves 20 in the direction of valve closure between the cylinder head 14 and the spring seats 22 provided at upper ends of the rods 20a of the intake valves 20. In addition, valve springs 25 are provided for diverting the exhaust valves 21 in the direction of valve closure between the cylinder head 14 and the spring seats 24 provided at upper ends of the rods 21a of the exhaust valves 21. An intake valve operation device 28 that drives the intake valves 20 for opening and closing operations includes an intake cam shaft 30 having intake valve operation cams 29 in a one-to-one relationship with the cylinders., the inlet rocker arms 31 which oscillate by pushing the intake valve operation cams 29 and each is linked and connected in common to a pair of intake valves 20 in each cylinder, and the variable lift mechanisms 32 provided in a one-to-one relationship with the cylinders. An exhaust valve operating device 33 that drives the exhaust valves 21 for opening and closing operations includes an exhaust camshaft 35 having exhaust valve operation cams 34 in a one-to-one relationship with the cylinders , and the exhaust rocker arms 36 that oscillate by pushing the exhaust valve operation cams 34 and each of which is linked and connected in common to a pair of exhaust valves 21 in each cylinder. The position of the motor body 11 is established by being inclined towards the side of the exhaust valve operation device 33 in such a way that the angle? between a cylinder C axis and a vertical VL line is 20 degrees, for example. Referring also to FIGURES 2 and 3, the upper retainers 38 are secured to the cylinder head 14, the two upper retainers 38 are disposed on opposite sides of each cylinder. The covers 39 and 40 forming the intake cam retainers 41 and the escape cam retainers 42 in association with the upper retainers 38 are secured to the upper retainers 38 from above. Accordingly, the intake camshaft 30 is rotatably supported between the upper retainers 38 and the covers 39 forming the intake cam retainers 39 while the exhaust camshaft 35 is rotatably supported between the upper retainers 38 and the caps 40. forming the escape cam retainers 42 in association with each other. The upper surface of each upper retainer 38 is interposed in such a way that the distance between the portion supporting the intake camshaft 30 and the combustion chamber 17 is larger than the distance between the portion supporting the camshaft 35 of exhaust and the combustion chamber 17. In this way, the intake camshaft 30 is arranged in a higher position than the exhaust camshaft 35 by increasing the distance between the intake camshaft 30 and the combustion chamber 17 along the C axis. of the cylinder of the motor body 11 relative to that between the exhaust camshaft 35 and the combustion chamber 17. The intake camshaft 30 and the exhaust camshaft 35 are driven and rotated by driving power transmitted from a crankshaft (not shown) in a reduction ratio of 1/2. The rotation direction 37 of the intake camshaft 30 is set such that the intake camshaft 30 rotates as it moves upwardly on the side where the intake camshaft 30 confronts the exhaust valve operation device 33. . The direction of rotation of the intake camshaft 30 is indicated in a clockwise direction in FIGURE 1. Each exhaust rocker arm 36 is supported in an oscillated manner at one end on a rocker shaft 43 Exhaust having an axis parallel to the exhaust camshaft 35 and supported on the upper retainer 38. A pair of screws 44 pusher-valves that are joined at the upper ends of the rods 21a of the pair of exhaust valves 21 are screwed into the exhaust rocker arm 36 at the other end thereof so that their forward positions / Retraction are adjustable. A shaft 45 parallel to the exhaust rocker shaft 36 is provided in an intermediate portion of the exhaust rocker arm 36. A roller 47 contacting the exhaust valve operation cam 34 in a rolling contact shape is supported axially on the exhaust rocker arm 36 with a roller bearing 46 interposed between the roller 47 and the shaft 45.

This exhaust valve operating device 33 is arranged in the cylinder head 14 such that the exhaust rocker arm 36 oscillatingly supporting the portion, ie the exhaust rocker arm shaft 43, is placed outside. of the portion for its connection and connection of the exhaust rocker arm 36 to the exhaust valves 21, that is, the thrust screws 44. Referring to FIGURES 4 and 5, each intake arm arm 31 has a valve connection portion 31a that is provided at its end. The pusher screws 49 which are spliced at the upper ends of the rods 20a of the pair of intake valves 20 from the top are screwed into the valve connection portion 31a such that the advance / retract positions are Adjustable The intake rocker arm 31 has at the other end a first support portion 31b and a second support portion 31c formed under the first support portion 31b continuously therewith, the first and second support portions 31b and 31c are formed as a generally U-shaped portion open on the opposite side of the intake valves 20. A roller 50 that contacts the intake valve operation cam 24 in a rolling contact shape is supported axially on the first support portion 31b of the intake arm arm 31 by a roller bearing 52 - and a first connection tree 51 The roller 50 is interposed between the opposite portions of the first support portion 31b generally U-shaped. Referring also to FIGURE 6, the intake rocker arm 31 is formed, for example, by die casting a light alloy. A thin portion 53 of a generally triangular shape for example, is formed in a central portion of an upper surface of the valve connecting portion 31a, and a pair of thin portions 54 are formed in two portions of a lower portion surface. 31a of opposite valve connection of the upper surface such that the thin portions 53 and 54 are alternately placed facing in opposite directions. The thin portions 53 and 54 are simultaneously formed at the time of the die casting of the rocker arm 31. The upper thin portion 53 has a shot in a direction such that the opening area of the thin portion 53 increases with the reach towards the upper surface of the valve connecting portion 31a, while the lower thin portions 54 have shots in the upper portion. such directions that the opening area in the thin portion 54 increases with the reach toward the bottom surface of the valve connection portion 31a. Consequently, the inclination direction of the inner surface of the thin portion 43 and the inclination direction of the inner surface of the thin portions 44 are parallel to each other and the wall portions 31d formed in the valve connection portion 31a between the 53 and 54 thin portions adjacent to each other are generally uniform in thickness. Referring also to FIGURES 7 and 8, the variable lift mechanism 32 has a first link arm 58 having one end rotatably connected to the first support portion 31b of the arm of the rocker arm 31 and the other end supported rotating in a fixed position on the motor body 11 by means of an intake rocker shaft 5 provided as a fixed support shaft, a second articulation arm 59 having one end rotatably connected to the second support portion 31c of the intake arm arm 31, a mobile support shaft 60 rotatably supporting the second articulation arm 59 at the other end, a control shaft 61 connected to the mobile support shaft 60 to enable an angular displacement of the shaft 60 of mobile support around an axis parallel to the axis of the mobile support shaft 60, and a drive motor 62 connected to the control shaft 61 to cause an angular displacement of the movable shaft 60. One end of the first articulation arm 58 is formed in such a way that it is generally U-shaped and interleaves the first support portion 31b of the intake arm arm 31 from opposite sides and is rotatably connected to the first support portion 31b by the first connecting shaft 51 that axially supports the roller 50 on the arm of the inlet rocker arm. The shaft 57 of the intake rocker arm that rotatably supports the other end of the first articulation arm 58 is supported on the upper retainers 38 secured to the cylinder head 14. One end of the second articulation arm 59 placed under the first articulation arm 58 is positioned in such a way that it is inserted into the second support portion 31c of the intake rocker arm 31 and is rotatably connected to the second support portion 31c by means of the second connection tree 63. The support projections 64 are provided in the form of projections integrally on the upper retainers 38 on opposite sides of the other end of the first articulation arm 58 to support the intake rocker shaft 57. The movement of the shaft 57 of the intake rocker arm in the axial direction at the other end of the first articulation arm 58 is limited by these support projections 64. The two intake valves 20 are biased in the valve closing direction by the valve springs 23. When the two intake valves 20 are spring-biased in the direction of valve closing, they are urged in the valve opening direction by the intake arm arm 31, the roller 50 of the intake arm arm 31 is kept in contact with the intake valve operation cam 29 by the action of the valve springs 23. However, when the intake valves 20 are in the closed state, the bending force of the valve springs 23 does not act on the intake rocker arm 31 to prevent the roller 50 from moving away from the operating cam 29. admission valve. There is a possibility that the precision of the valve lift control is reduced when the intake valves 20 are slightly open. Therefore, the intake rocker arm 31 is deflected by the rocker arm offset springs 65 spaced apart from the valve springs 23 in a direction to be put into engagement against the intake valve operation cam 29.

The rocker deflection springs 65 are spiral torsion springs which surround the support projections 64 and are provided between the motor body 11 and the rocker arm 31. That is, the ends of the rocker bending springs 65 are engaged with the supporting projections 64 while the other ends of the rocker bending springs 65 are inserted into, and in engagement with, the first connecting shaft 51 provided as a hollow shaft that operates integrally with the arm 31 of the inlet rocker arm. A portion of the first articulation arm 58 at the other end is formed in a cylindrical conformation, with its circumference positioned to be observed from within the circumference of the rocker deviation springs 65 wound in a spiral shape, when viewed laterally. At the axially opposite ends of the other end portion of the first articulation arm 58, a plurality of projections, for example, a pair of projections 66 and 67, circumferentially spaced apart from one another, are provided to prevent the springs 65 from deviating from each other. rocker fall to the first articulation arm 58. In this way, while avoiding increasing the size of the other end portion of the first joint arm 58, the above-described drop of the rocker bending springs 65 can be avoided and the support stiffness of the other end portion of the first articulation arm 58 can be increased. The projections are kept clear of the working area of the second articulation arm 59, thereby maintaining the desired working area of the second articulation arm 59, although projections 66 and 67 are provided in the other end portion of the first articulation arm 58. . The oil jets 68 for supplying oil to an upper portion of the intake rocker arm 31 at the other end are mounted on the covers 39 in the intake camshafts 41 provided in the engine body 11. A path 69 for driving oil from an oil pump (not shown) is provided in one of a plurality of top retainers 38. Circular arc outlets 70 are formed in upper portions of the upper retainers 38 to confront the lower half of the intake camshaft 30. The path 69 communicates with one of the circular arc recesses 70. On the other hand, an oil path 71 is coaxially formed in the intake cam shaft 30. Communication holes 72 having inner ends communicating with the oil path 71 are formed in the intake camshaft 30 at positions corresponding to the intake camshafts 41 to have openings formed at their outer ends on the surface exterior of the intake camshaft 30. Lubricating oil is provided in the space between the cam carriers 41 and the intake camshaft 30 via the communication holes 72. Also, the recesses 73 are provided in the lower surfaces of the caps 39 and which form the intake cam carriers 41 in association with the upper retainers 38. The recesses 73 form a path between the bottom surfaces of the covers 39 and the top surfaces of the top retainers 38 to communicate with the recesses 70. The oil jets 68 are mounted on the covers 39 to communicate with paths 74 formed in the covers 39 for communication with the recesses 73. In this way, the oil jets 68 are mounted on the covers 39 of the intake cam carriers 46 provided on the motor body 11 to rotatably support the intake camshaft 30, thereby allowing a sufficient quantity of oil to be provided at a sufficiently high pressure from the oil jets 68 when using the oil paths for lubrication between the intake camshaft 30 and the intake camshafts 41. As well, the oil is provided from the oil jets 68 to the first hinge shaft 51 in the upper position in the first and second hinge shafts 51 and 63 by whose ends the first and second hinge arms 58 and 59 are connected to the arm 31 of the inlet rocker arm, so that the oil that has been lubricated between the first joint arm 58 and the inlet rocker arm 31 flows decently to the second articulation arm 59 in the lower position. Oil introduction holes 75 and 76 having intermediate portions confronting portions of the movable support shaft 60 and the second hinge shaft 63 are provided in the second hinge arm 59 in a direction perpendicular to a straight line connecting the axes of the the mobile support shaft 60, and the second hinge shaft 63 and the oil introduction holes 75 and 76 have an opening that confronts the first hinge shaft 51. Therefore, the oil flowing down from the first articulation arm 58 is effectively led into the space between the second articulation arm 59 and the movable support shaft 60 and the space between the second articulation arm 59 and the second articulation 63 joint. In this way, the lubrication in the inlet arm arm 31, the lubrication in the connection between the first and second hinge arms 58 and 59 and the lubrication between the second hinge arm 59 and the mobile support shaft 60 can be performed by means of a simple lubrication structure having a reduced number of component parts to ensure smooth valve operations. The control shaft 61 is a single shaft supported on the motor body 11 as a common component associated with the plurality of cylinders accommodated in line. The control shaft 61 is formed in a crankshaft configuration and has, in correspondence with each cylinder, two webs 61a placed on opposite sides of the arm of the rocker arm, bearings 61b rotatably supported on the engine body 11 and a portion 61c of articulation connecting the two souls 61a. The mobile support shaft 60 is connected to the control shaft 61 to connect each pair of webs 61a. The bearing case 61b of the control shaft 61 is rotatably supported between the upper retainer 38 connected to the cylinder head 14 of the motor body 11 and a lower retainer 77 connected to the upper retainer 38 from below. Lower retainer 77 is formed separately from cylinder head 14 and is secured to upper retainer 38. A recess 78 to allow placement of the lower retainer 77 is provided on the upper surface of the cylinder head 14. Roller bearings 79 are interposed between the upper and lower retainers 38 and 77 and the bearings 61b. The roller bearings 79 are of a dividable type as they are interposed between the upper and lower retainers 38 and 77 and the bearings 61b of the control shaft 61 having a plurality of webs 61a and the articulation portions 61c and are provided as a common component associated with the plurality of cylinders. The control shaft supporting the support shafts 80 of the control shaft projecting to the sides of the web 61a of the control shaft 61 are formed in the upper and lower retainers 38 and 77 to pass through the bearings 61a. In the upper retainers 38 and the lids 39 connected to each other to form the intake camshafts 41 in association with each other, the camshaft support projections 81 through which the intake camshaft 30 is passed is they form to project towards the inlet rocker arms 31. In the upper retainers 38, the flanges 82 for connection between the support projections 80 of the control shaft and the camshaft support projections 81 are formed integrally to project from them. The trajectories 83 for driving the oil to the roller bearings 79 are provided in the flanges 82 to provide communication with the recesses 70 in the upper surfaces of the upper retainers 38. While the exhaust valve operating device 33 is accommodated in the cylinder head 14 so that the oscillating support portion of the exhaust rocker arm 36 is positioned outside the portion for attachment and connection of the rocker arm 36 exhaust to the exhaust valves 21, the above-described inlet valve operation device 28 is accommodated in the cylinder head 14 so that the intake rocker shaft 57 and the movable support shaft 60 are placed within the portion for attachment and connection of the arm 31 of the intake rocker to the intake valve 20. In addition, a spark plug cylinder 87 into which a spark plug 86 is inserted to mount on the cylinder head 14 to face the combustion chamber 17 is provided on the cylinder head 14 between the intake valve operation device 28. and the exhaust valve operation device 33. The spark plug cylinder 87 tilts as it gets closer to the exhaust valve operating device at a position closer to its upper end. In this way, the control shaft 61 in the intake valve operation device 28 is positioned between the intake valves 20 and the spark plug cylinders 87, with outer surfaces of the articulation portions 61c confronting the spark plug cylinders 87. Gap grooves 88 to avoid interference with the spark plug cylinders 87 are formed on the outer surfaces of the articulation portions 61c. When the intake valves 20 are in the closed state, the second hinge shaft 63 connecting the second hinge arm 59 to the intake rocker arm 31 is coaxial with the bearings 61b of the control shaft 61. When the control shaft 61 oscillates on the axis of the bearings 61b, the mobile support shaft 60 moves in a circular arc of a circle at the center of which corresponds to the axis of the bearings. With reference to FIGURES 9 and 10, one of the bearings 61b of the control shaft 61 is removed from a support hole 89 provided in the cover 15 of the head. A control arm 91 is fixed on the tip of the bearing 61b and is driven by the drive motor 62 mounted on an outer wall of the cylinder head 14. That is, a nut member 93 meshes with a threaded shaft 92 rotated by the drive motor 62, and an articulation strut 95 having its end pivotally supported by a pin 94 which is connected at the other end to the arm 91 of control by pins 96. Therefore, when the driving motor 62 is operated, the nut member 93 moves along the rotating threaded shaft 92, and the control shaft 61 is oscillated about the bearing 61b by the arm 91 of control connected to the nut member 93 by the joint brace 95, thereby causing displacement of the movable support shaft 60. A rotational angle sensor 97 such as a rotary encoder is installed on an exterior wall surface of the head cover 15 with one end of a sensor arm 98 attached to the tip of a sensor shaft 97a. A guide groove 99 is formed in the control arm 91 to extend linearly in the longitudinal direction of the control arm 91, and a hinge shaft 100 mounted on the other end of the sensor arm 98 slidably fits in the groove 99 of guide. The threaded shaft 92, the nut member 93, the pin 94, the articulation strut 95, the pins 96, the control arm 91, the rotational angle sensor 97, the sensor arm 98 and the articulation shaft 100 are they house in a housing 101 mounted on the side surface of the cylinder head 14 and the cover 15 of the bolt head 102. A cover 103 covering the open end surfaces of the housing 101 is mounted on the housing 101 by the member 104 of screw. In the variable lifting mechanism 32, when the control arm 91 is rotated counterclockwise by the driving motor 62 from the position located in FIGURE 9, the control shaft 61 connected to the control arm 91 it also rotates in the counterclockwise direction to move the mobile support tree 60 downwardly. When the intake valve operation cam 29 in the intake camshaft 30 pushes the roller 50 in this state, a four-bar linkage connecting the intake rocker shaft 57, the first joint shaft 51, the second articulation shaft 63 and the mobile support shaft 60 deforms and causes the intake rocker arms 31 to swing downwardly . The pusher screws 49 with this push the rods 20a of the intake valves 20, finally opening the intake valves 20 with a low lift. When the control arm 91 is rotated to the thick line position in FIGURE 9 by the driving motor 62, the control shaft 61 connected to the control arm 91 rotates in the clockwise direction to move the shaft 60. of mobile support asing. When the intake valve operation cam 29 in the intake camshaft 30 pushes the roller 50 in this state, the four-bar stay deforms and causes the intake rocker shafts 31 to swing downwardly. The pusher screws 49 push the rods 20a of the intake valves 20 thereby finally opening the intake valves 20 with a high lift. The operation of this modality will now be described. The intake camshaft 30 is positioned higher up in the position than the exhaust camshaft 35 by increasing the distance between the intake camshaft 30 and the combustion chamber 17 along the cylinder axis C of the body. 11 of the motor relative to that between the exhaust camshaft 35 and the combustion chamber 17, thereby making it easier to cause the lubricating oil to flow to the exhaust valve operation device 33 after the lubrication and cooling of the exhaust valve. inlet valve operation device 28 maintained at a relatively low temperature, and making it possible to effectively lubricate and cool the valve of the exhaust valve operation device 33 under thermally severe conditions. The intake valve operation device 28 has the variable lift mechanism 32 capable of changing the valve opening elevation of the intake valve 20 and the exhaust valve operation device 33 has the exhaust camshaft 35 and the exhaust rocker arm 36 linked and connected to the exhaust valves 21 to be able to oscillate by pushing the exhaust camshaft 35. The elevation of the intake valves 20 is changed by the variable lift mechanism 32. In this way, the amount of air intake can be controlled without using the regulating valve. In addition, the variable lift mechanism 32 can be effectively accommodated in a space on the side of the intake valve operation device 28 where there is more space than that on the side of the exhaust valve operation device 33. The portion of the motor body 11 is set so that the cylinder axis C is inclined towards the exhaust valve operating device 33. Therefore, the lubricating oil flows efficiently to the exhaust valve operating device 33 after lubricating and cooling the intake valve operation device 28. In this way, the lubrication and cooling of the exhaust valve operation device 33 can be performed more efficiently. The rotation direction 37 of the intake camshaft 30 is set so that the intake camshaft 30 rotates as it moves upwardly on the side where the intake camshaft 30 confronts the exhaust valve operation device 33. An upward splash of the lubricating oil towards the exhaust valve operating device 33 is caused by this rotation of the intake camshaft 30 to more efficiently lubricate and cool the exhaust valve operation device 33. In the variable lift mechanism 32 for continuously changing the valve opening elevation of the intake valves 20, the ends of the first and second articulation arms 58 and 59 are connected relatively in a movable manner parallel to each other towards the intake arm arm 31 having the valve articulation portion 31a connected and connected to the pair of intake valves 20 , the other end of the first articulation arm 58 is rotatably supported by the intake rocker shaft 57 supported on the engine body 11, and the other end of the second articulation arm 59 is rotatably supported by the mobile support shaft 60 capable to move. Therefore, the elevation of the intake valves 20 can be changed alternately by reciprocating the movable support shaft 60. Also, the ends of the first and second articulation arms 58 and 59 are connected rotary directly to the arm of the intake rocker arm 31, so that the space in which the two articulation arms 58 and 59 are arranged is reduced, this mode making the valve operation device compact. Since the driving power is transmitted directly from the intake valve operation cam 29 to the roller 50 of the intake rocker arm 31, an improved flow capacity can be ensured towards the intake valve operation cam 29. Also, the intake rocker arm 31 and the first and second articulation arms 58 and 59 can be disposed substantially in the same position in the direction along the axis of the intake camshaft 30, thereby making the device compact. of intake valve operation in the direction along the intake camshaft 30. One end of the first articulation arm 58 is rotatably connected to the intake arm arm 31 via the first hinge shaft 51, and the roller 50 is supported axially on the intake arm arm 31 by the first hinge shaft 51. That is, the connection of one end of the first articulation arm 58 to the intake rocker arm 31 allows the rotation of the first articulation arm 58 and the axial support of the roller 50 in the intake rocker arm 31 are achieved by means of the first articulation shaft 51, thereby reducing the number of component parts and making the operating valve operation device 28 more compact. In the intake valve operating device 28 having the variable lift mechanism 32 in the intake and exhaust valve operation devices 28 and 33, the intake rocker shaft 57 and the mobile support shaft 60 are placed within the portion for the connection and connection of the intake rocker arm 31 to the intake valves 20, while the portion of the exhaust valve operation device 33 for oscillatingly supporting the rocker arm 36 is positioned outside the portion for connecting and connecting the exhaust rocker arm 36 to the exhaust valves 21. Therefore, it is possible to avoid mutual interference between the intake valve operation device 28 and the exhaust valve operation device 33 while preventing an increase in the size of the cylinder head 14 where in one case the angle a content between the intake valves 20 and the exhaust valves 21 (see FIGURE 1) is set to be small in order to reduce the size of the combustion chamber 17 to obtain good combustion. The valve operation device 33 has the exhaust camshaft 35 having the exhaust valve operation cams 34, and the exhaust rocker arms 36 oscillatingly supported on the engine body 11 by the rocker shaft 43 escape to oscillate by pushing the escape valve operation cam 35 and linked and connected to the exhaust valves 21. Also, the spark plug cylinder 68 positioned between the intake valve operating device 28 and the exhaust valve operating device 33 is mounted on the cylinder head 14 when tilted to become closer to the valve operation device 33. escape in a position closer to its upper end. In this way, the spark plug cylinder 68 is positioned to avoid interference with the intake valve operation device 28 and the exhaust valve operation device 33. This placement contributes to the effect of making the entire cylinder head 14 more compact. The control shaft 61 provided in the variable elevation mechanism 32 of the intake valve operation device 28 is connected to the mobile support shaft 60 to allow angular displacement of the mobile support shaft 60 on an axis parallel to the axis of the shaft 60 of movable support and are supported on the motor body 11 on opposite sides of the arm of the inlet rocker arm. The stiffness of the support for the control shaft 61 is increased by adopting the double support structure to allow variable elevation control and the intake valves 20 to be performed accurately. The simple control shaft 61 described above is supported on the motor body 11 as a common component associated with the plurality of cylinders arranged in line. Therefore, it is possible to make the motor E compact by avoiding the increase in the number of component parts. In addition, the control shaft 61 is formed in a crankshaft configuration and has the two webs 61a positioned on opposite sides of the arm of the rocker arm 31, the bearings 61b attached perpendicular to the outer surfaces of the end portions of the base of the rocker arms. two webs 61a and rotatably supported in the motor body 11, and the articulation portion 61c connecting the two webs 61a. The mobile support shaft 60 is connected to the control shaft 61 to connect the two webs 61. Therefore, the rigidity of the driven control shaft 61 can be increased to move angularly. The bearings 61b of the control shaft 61 are rotatably supported between the upper retainers 38 connected to the cylinder head 14 of the motor body 11 and the lower retainers 77 connected to the upper retainers 38 from below. In this way, the ease with which the control shaft 61 is mounted on the motor body 11 can be improved. Further, since the lower retainers 77 separated from the cylinder head 14 are attached to the upper retainers 38, the degree of freedom with which the cylinder head 14 is designed with respect to supporting the control shaft 61 can be increased. The divisible roller bearing 79 is interposed between the upper and lower retainers 38 and 77 and the bearings 61b to improve the ease with which the control shaft 61 is mounted to the motor body 11 while reducing the loss due to friction in the portions supporting the control shaft 61. The control shaft support projections 80 projecting to the sides of the core 61a of the control shaft 61 are formed in the upper and lower retainers 38 and 77 connected to each other, and the bearings 61b passed through the projections 80 of Control shaft supports are rotatably supported between upper and lower retainers 38 and 77. Therefore, the stiffness of the support for the control shaft 61 can be further increased. The camshaft support projections 81 projecting towards the intake rocker arm 31 are formed in the upper retainers 38 in the caps 39 connected to the upper retainers 38 from above. The intake camshaft 30 is passed through the camshaft support projections 81 and rotatably supported between the upper retainers 38 in the caps 39. Therefore, it is possible to increase the rigidity of the support for the shaft 30. of intake cams while minimizing the number of component parts to support the intake camshaft 30. The flanges 82 for the connection between the support projections 80 of the control shaft and the camshaft support projections 81 are formed in the upper retainers 38 to project from there to further increase the rigidity of the supports for the shaft 61 control and the intake camshaft 30. The control shaft 61 is positioned between the intake valves 20 and the spark plug cylinders 87 provided in the cylinder head 14, with the outer surfaces of the articulation portions 61c facing the spark plug cylinders 87. The clearance grooves 88 to avoid interference with the spark plug cylinders 87 are formed on the outer surfaces of the articulation portions 61c. Therefore, the spark plug cylinders 87 can be placed closer to the intake valve operating device 28 to make the engine E compact. The intake rocker arm 31 of the intake valve operation device 28 has portions 53 and 54 The thin portions formed on the surfaces of the valve joint portion 61 opposite each other, the thin portions 53 and 54 are alternately positioned facing each other in opposite directions. Therefore, the arm of the rocker arm can be reduced in weight. The thin portions 53 and 54 are formed simultaneously at the time of the die casting of the rocker arm 31. Each of the adjacent pairs of the thin portions 53 and 54 have shots in reversed directions with each other, so that the inner surfaces of the adjacent pair of the thin portions 53 and 54 are inclined in the same direction. Therefore, the wall portions 31d formed in the intake rocker arm 31 between the thin portions 53 and 54 adjacent to each other are generally uniform in thickness. The desired stiffness of the inlet rocker arm 31 can be maintained by forming wall portions 31d generally uniform in thickness. The intake valve operation device 28 has the variable elevation mechanism 32 capable of alternately changing the elevation of the intake valves 20. Therefore, the number of component parts in the intake valve operation device 28 is comparatively large. Even in the intake valve operation device 28 having the variable lift mechanism 32 responsible for being a cause of weight increase of the intake valve operation device 28, the weight of the intake valve operation device 28 may reduce by reducing the weight of the arm of the rocker arm 31, thereby increasing the critical rotational speed. The embodiment of the present invention is as described in the foregoing. The present invention, however, is not limited to the modality described in the foregoing. Various changes in design can be made without departing from the scope of the invention described in the appended claims. For example, the embodiment has been described with respect to a case where the spark plug cylinder 87 is positioned between the intake valve operating device 28 and the exhaust valve operating device 33, the present invention can also be applied to a engine in which a fuel injection valve for directly injecting fuel into the combustion chamber 17 is positioned between the intake valve operating device 28 and the exhaust valve operating device 33.

Claims (7)

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and therefore the property described in the following claims is claimed as property. CLAIMS

1. An engine comprising: a cylinder head that forms a portion of a motor body; an intake valve operation device having an intake camshaft; an inlet valve operated for opening and closing operations by the intake valve operation device, the intake valve is provided in the cylinder head; an exhaust valve operation device having an exhaust camshaft; and an exhaust valve operated for opening and closing operations by the exhaust valve operating device, the exhaust valve is provided in the cylinder head, characterized in that the intake camshaft is positioned higher in its position than the exhaust camshaft by increasing the distance between the intake camshaft and a combustion chamber along a cylinder axis (C) of the engine body relative to the distance between the exhaust camshaft and the exhaust camshaft; the combustion chamber. The motor according to claim 1, characterized in that the intake valve operation device has a variable lifting mechanism capable of changing the amount of valve opening elevation of the intake valve, and the operation device of the valve. Exhaust valve has the exhaust camshaft and the exhaust rocker arm bonded and connected to the exhaust valve to oscillate by pushing the exhaust camshaft. The motor according to claim 1, characterized in that the motor body is placed in a position such that the cylinder axis is inclined towards the valve operating device. The motor according to claim 1, characterized in that the direction of rotation of the intake camshaft is set so that the intake camshaft rotates as it moves upwardly on the side where the intake camshaft confronts the intake camshaft. Exhaust valve operation device. The engine according to claim 2, characterized in that the intake valve operation device includes the intake camshaft having an intake valve operation cam, an intake rocker arm having a portion of cam contact making contact with the intake valve operation arm, the intake rocker arm which is connected and connected to the intake valve to apply a force to the intake valve in the valve operation direction, and the variable lifting mechanism, and wherein the variable lifting mechanism has a first articulation arm having one end thereof rotatably connected to the intake rocker arm and the other end rotatably supported at a fixed position on the body of an engine a through a fixed support shaft, and a second articulation arm having one end thereof rotatably connected to the arm of Intake rocker and the other external supported rotatably in a mobile support tree able to move. The motor according to claim 5, characterized in that the fixed support shaft and the mobile support shaft are placed within a portion for the connection and connection of the intake rocker arm to the intake valve, and a portion thereof. of the exhaust valve operating device for oscillatingly supporting the exhaust rocker arm which is positioned outside a portion for its connection and connection of the exhaust rocker arm and the exhaust valve. The engine according to claim 6, characterized in that a tilted spark plug cylinder to be placed closer to the exhaust valve operating device in a position closer to an upper end thereof is mounted on the cylinder head when being placed between the intake valve operation device and the exhaust valve operation device.