JP2007205299A - Cylinder head of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder head fitting to various types of cylinder heads by merely changing less number of parts. <P>SOLUTION: This cylinder head of an internal combustion engine comprises a cylinder head body 31 having intake and exhaust valves 34, 35 and valve springs 38 and a support stand part installed on the cylinder head body 31. The support stand part is formed of one of a first cam carrier 41 on which the intake and exhaust camshafts 42, 44 are rotatably supported so that the intake and exhaust cams 43, 45 of the intake and exhaust camshafts 42, 44 directly push down the intake and exhaust valves 34, 35 and a second cam carrier 61 on which the intake and exhaust camshafts 42, 44 are rotatably supported so that the intake and exhaust cams 43, 45 of the intake and exhaust camshafts 42, 44 indirectly push down the intake and exhaust valves 34, 35 through and rocker arm 71. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cylinder head of an internal combustion engine in which an engine valve urged in a valve closing direction by a valve spring is opened by a valve operating mechanism.

  A general valve mechanism in a cylinder head of an internal combustion engine is such that an engine valve (suction / exhaust valve) urged in a valve closing direction by a valve spring is directly or indirectly via a camshaft cam or a rocker arm. A configuration is adopted in which the valve is pushed down to open. That is, as a valve opening / closing mechanism for opening / closing the engine valve, a direct acting (direct hitting) valve opening / closing mechanism or a rocker arm type valve opening / closing mechanism is employed.

  In the direct-acting valve opening / closing mechanism, a valve lifter is attached to the upper end portion of the valve stem of the engine valve. When the valve lifter is pressed by the cam by the rotation of the camshaft, the engine valve is pushed down against the valve spring to open. Such a direct-acting valve opening / closing mechanism is also referred to as a valve lifter-type valve opening / closing mechanism.

  In the rocker arm type valve opening / closing mechanism, the rocker arm is disposed on the valve stem and the lash adjuster of the engine valve. When the rocker arm is pressed by the cam by the rotation of the camshaft, the rocker arm swings with the head of the lash adjuster as a fulcrum. By this swing, the engine valve is pushed down against the valve spring and opened. Among such rocker arm type valve opening / closing mechanisms, a roller arranged at a portion pressed by the rocker arm cam is called a roller arm type valve opening / closing mechanism.

  On the other hand, in recent years, it has been proposed to provide a variable valve characteristic device in the cylinder head. The variable valve characteristic device is a device that changes valve characteristics such as a maximum lift amount of an engine valve and an operating angle of a cam related to opening of the engine valve in accordance with an operating state of the internal combustion engine. When such a variable valve characteristic device is applied to, for example, an intake valve, the intake cam amount is limited by reducing the working angle of the intake cam and the maximum lift amount of the intake valve in a low rotation and low load region of the internal combustion engine. Thus, the pumping loss caused by the throttle valve opening control can be reduced, and the fuel consumption can be improved. Further, in the high rotation and high load region of the internal combustion engine, the operating angle and the maximum lift amount can be increased, and an increase in output can be ensured by improving the intake charging efficiency.

One embodiment of such a valve characteristic varying device includes a slider provided so as to be displaceable in the axial direction, and an input arm and an output arm each meshed with the outer periphery of the slider by a helical spline ( For example, see Patent Document 1). In this valve characteristic variable device, when the input arm is swung by the cam, the swing is transmitted to the output arm via the slider, and the output arm is swung. By this swinging, the engine valve is pushed down against the valve spring to open. In addition to this basic operation, when the slider is displaced in the axial direction by the actuator, the relative phase difference between the input arm and the output arm is changed by the rotation of the slider accompanying this displacement, and the operating angle and the maximum lift amount are changed. The
JP 2001-263015 A

  By the way, a cylinder head provided with a direct-acting valve opening / closing mechanism and a cylinder head provided with a rocker arm type valve opening / closing mechanism differ only in the components at the top of the cylinder head, such as a valve lifter, rocker arm, and lash adjuster. Other components such as intake / exhaust camshafts, intake / exhaust valves, valve springs and the like are common, and the configuration of the lower part of the cylinder head may also be common. Therefore, in such a case, it is desirable to adopt a configuration in which common portions can be shared regardless of whether the valve opening / closing mechanism provided in the cylinder head is a direct acting type or a rocker arm type.

  Further, in the cylinder head of the base to which the valve characteristic variable device is incorporated and the cylinder head in which the valve characteristic variable device is incorporated, other components other than the valve characteristic variable device, for example, intake / exhaust camshaft, Intake / exhaust valves, valve springs, etc. are common. Therefore, for example, when a base cylinder head that does not have a function to change valve characteristics already exists and a cylinder head to which a function to change valve characteristics is added is newly set, the former cylinder head as a base In this case, it is desirable to use a portion common to the latter cylinder head. This diversion makes it possible to suppress investment for newly adding production equipment (factories, machines, etc.).

  However, in the technique described in Patent Document 1, such a point is not considered, and two types of cylinder heads including a common part are manufactured separately. Therefore, there is room for improvement from the viewpoint of restraining investment in the manufacturing equipment described above.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to be able to cope with various types of cylinder heads only by changing fewer parts. To do.

  In the present invention, means for solving the above-described problems are configured as follows. That is, the present invention relates to a cylinder of an internal combustion engine provided with an engine valve, a valve spring that urges the engine valve in the valve closing direction, and a camshaft that drives the engine valve in the valve opening direction against the valve spring. A cylinder head main body in which the engine valve and the valve spring are assembled, and a first support base portion on which the camshaft is rotatably supported so that the cam of the camshaft directly pushes down the engine valve. And the camshaft cam is selected from a second support base that is rotatably supported so that the cam of the camshaft indirectly pushes down the engine valve via the rocker arm, and is attached to the cylinder head body. It is characterized by comprising a support base portion.

  According to the above configuration, two types of first support base and second support base are prepared in advance as support bases that constitute the cylinder head together with the cylinder head body. One of the two types of support bases is selected according to a valve opening / closing mechanism provided in the cylinder head. The cylinder head body is commonly used regardless of the valve opening / closing mechanism provided in the cylinder head. When the cylinder head is manufactured, the support base selected as described above is attached to the cylinder head body.

  Specifically, when a direct-acting type in which the cam of the camshaft directly pushes down the engine valve is employed as the valve opening / closing mechanism, the first support base is selected as the support base. On the other hand, when a rocker arm type in which the camshaft cam pushes the engine valve indirectly through the rocker arm is adopted as the valve opening / closing mechanism, the second support base is selected as the support base. It is.

  In this way, by sharing only the cylinder head body, depending on the valve opening / closing mechanism provided in the cylinder head, only one of the two types of support bases is selected and attached to the cylinder head body, thereby reducing the number of parts. The cylinder head having a direct acting valve opening / closing mechanism or the cylinder head having a rocker arm type valve opening / closing mechanism can be obtained only by changing the above. As a result, it is possible to suppress investment for newly adding cylinder head manufacturing facilities (factories, machines, etc.), and to reduce the cost of the cylinder head.

  The present invention also provides a cylinder for an internal combustion engine provided with an engine valve, a valve spring that urges the engine valve in the valve closing direction, and a camshaft that drives the engine valve in the valve opening direction against the valve spring. A cylinder head main body in which the engine valve and the valve spring are assembled, and a first support base portion on which the camshaft is rotatably supported so that the cam of the camshaft directly pushes down the engine valve. The camshaft is rotatably supported so that the camshaft cam indirectly pushes the engine valve through the rocker arm, and a valve characteristic variable device for changing the valve characteristic of the engine valve is assembled. And a support base part attached to the cylinder head body. It is characterized in that to obtain.

  According to the above configuration, two types of the first support base and the third support base are prepared in advance as the support base that constitutes the cylinder head together with the cylinder head body. One of the two types of support bases is selected according to the necessity of the variable function of the valve characteristic of the engine valve. The cylinder head body is commonly used regardless of whether or not the variable function of the valve characteristic of the engine valve is necessary. When the cylinder head is manufactured, the support base selected as described above is attached to the cylinder head body.

  Specifically, when the variable function of the valve characteristic is not necessary, the first support base is selected as the support base. In the cylinder head in which the first support base is attached to the cylinder head body, the engine valve is pushed down against the valve spring by the rotating camshaft to open the valve.

  On the other hand, when the variable function of the valve characteristic is required, the third support base is selected as the support base. In the cylinder head in which the third support base is attached to the cylinder head, the rotation of the camshaft is transmitted to the engine valve through the valve characteristic variable device. By this transmission, the engine valve is pushed down against the valve spring to open. Further, when the variable valve characteristic device performs the variable function of the valve characteristic, the valve characteristic of the engine valve driven by the camshaft, for example, the operating angle which is the rotation angle of the cam related to the opening of the engine valve, The maximum lift amount is changed.

  In this way, by sharing only the cylinder head main body and selecting only one of the two types of support bases according to the necessity of the variable function of the valve characteristics and attaching it to the cylinder head main body, fewer parts can be obtained. A cylinder head having a variable function of a valve characteristic can be used or a cylinder head not having the function can be changed only by changing. As a result, it is possible to suppress investment for newly adding cylinder head manufacturing facilities (factories, machines, etc.), and to reduce the cost of the cylinder head.

  Further, as the valve opening / closing mechanism, the direct acting type valve opening / closing mechanism is less expensive than the rocker arm type valve opening / closing mechanism. Therefore, when the variable function of the valve characteristic is unnecessary, a cylinder head that does not have the variable function of the valve characteristic can be manufactured at a lower cost by adopting a direct-acting valve open / close mechanism as the valve open / close mechanism. .

  The present invention also provides a cylinder for an internal combustion engine provided with an engine valve, a valve spring that urges the engine valve in the valve closing direction, and a camshaft that drives the engine valve in the valve opening direction against the valve spring. A cylinder head main body in which the engine valve and the valve spring are assembled, and a first support base portion on which the camshaft is rotatably supported so that the cam of the camshaft directly pushes down the engine valve. A second support base rotatably supported by the camshaft so that the camshaft cam indirectly pushes the engine valve through the rocker arm; and the camshaft cam via the rocker arm. The camshaft is rotatably supported so as to push down indirectly, and changes the valve characteristics of the engine valve Consists either the fit of the valve characteristic varying device is selected from the third support section assembled is characterized in that it comprises a support section attached to the cylinder head body.

  According to the above configuration, three types of first support base, second support base, and third support base are prepared in advance as support bases that constitute the cylinder head together with the cylinder head body. One of the three types of support bases is selected according to the necessity of the variable function of the valve characteristic of the engine valve and the valve opening / closing mechanism provided in the cylinder head. The cylinder head body is commonly used regardless of the necessity of the variable function of the valve characteristic of the engine valve and the valve opening / closing mechanism provided in the cylinder head. When the cylinder head is manufactured, the support base selected as described above is attached to the cylinder head body.

  In this way, while sharing the cylinder head body, depending on the necessity of the variable function of the valve characteristic of the engine valve and the valve opening / closing mechanism provided in the cylinder head, one of the three types of support bases is selected. By selecting and attaching to the cylinder head main body, various types of cylinder heads can be handled with only a few parts being changed. Thereby, the investment for newly adding cylinder head manufacturing facilities (factories, machines, etc.) can be suppressed, and as a result, the cost of the cylinder head can be reduced.

  According to the present invention, it is possible to cope with various types of cylinder heads by changing fewer parts. Therefore, an investment to newly add cylinder head manufacturing facilities (factories, machines, etc.) can be made. Therefore, the cost of the cylinder head can be reduced.

  The best mode for carrying out the present invention will be described with reference to the accompanying drawings.

  Below, the example which applied this invention to the internal combustion engine (engine) mounted in a vehicle is demonstrated.

  The engine of this example is an in-line four-cylinder gasoline engine mounted on a vehicle, and includes a cylinder block and a cylinder head.

  The cylinder block 10 has four cylinders (cylinders) 11 arranged in a row, as shown in FIGS. A piston 12 is accommodated in each cylinder 11 of the cylinder block 10 so as to be reciprocally movable. Each piston 12 is connected to a crankshaft 13 that is an output shaft via a connecting rod. Therefore, when each piston 12 reciprocates, the movement is converted into a rotational movement by the connecting rod and then transmitted to the crankshaft 13. In each cylinder 11, the space above the piston 12 is a combustion chamber 14.

  On the other hand, as the cylinder head, a cylinder head 20A as shown in FIG. 1A and a cylinder head 20B as shown in FIG. 1B are set. Hereinafter, the cylinder heads 20A and 20B will be sequentially described.

  First, the cylinder head 20A will be described with reference to FIG.

  The cylinder head 20A includes a main assembly 30 that occupies most of the cylinder head 20A, and a subassembly 40A that is selectively attached on the main assembly 30. As shown in FIG. 2, the main assembly 30 includes a cylinder head body 31 and various components assembled to the cylinder head body 31. The cylinder head body 31 has a pair of intake ports 32 forming part of the intake passage and exhaust ports 33 forming part of the exhaust passage for each cylinder 11 in the cylinder arrangement direction (left and right direction in FIG. 3). Is formed.

  The cylinder head body 31 is provided with an intake valve 34 for opening and closing each intake port 32 and an exhaust valve 35 for opening and closing each exhaust port 33 as an engine valve. A retainer 37 is mounted on the upper end of each valve stem 36 of the intake / exhaust valves 34, 35. A valve spring 38 is disposed between each retainer 37 and the cylinder head body 31 and around each valve stem 36. The intake / exhaust valves 34 and 35 are both urged by a valve spring 38 in the direction of closing the intake / exhaust ports 32 and 33 (valve closing direction, substantially upward in FIG. 2).

  On the other hand, the subassembly 40A includes a first cam carrier 41 as a first support base disposed on the upper side of the cylinder head body 31. The first cam carrier 41 is fastened to the cylinder head body 31 by fastening parts such as bolts. The first cam carrier 41 lifts the intake / exhaust valves 34 and 35 in a direction to open the intake / exhaust ports 32 and 33 (opening direction, substantially downward in FIG. 2) against the valve spring 38 and the like. For this purpose, a valve opening / closing mechanism (valve mechanism) is provided. As this valve opening / closing mechanism, a direct acting type (valve lifter type) is adopted as will be described later.

  The valve opening / closing mechanism will be described. As shown in FIGS. 2 to 4, first bearing portions 46 are provided in a plurality of locations corresponding to each cylinder 11 in the cylinder arrangement direction of the first cam carrier 41. Yes. In each first bearing portion 46, a recess 47 is formed substantially above the intake valve 34, and the intake camshaft 42 having the intake cam 43 is connected to the first bearing portion 46 and the first cam cap in the recess 47. 48 and is rotatably supported. The first cam cap 48 is fastened to the first bearing portion 46 by a bolt 49 with the shaft portion of the intake cam shaft 42 covered from above.

  In each first bearing portion 46, a recess 51 is formed substantially above the exhaust valve 35, and the exhaust camshaft 44 having the exhaust cam 45 is connected to the first bearing portion 46 and the first in the recess 51. The cam cap 52 is rotatably supported. The first cam cap 52 is fastened to the first bearing portion 46 by a bolt 53 with the shaft portion of the exhaust camshaft 44 covered from above. Note that one end portion (left end portion in FIG. 3) of each of the intake / exhaust cam shafts 42 and 44 is rotatably supported by a first cam cap 54 and a first bearing portion 46 common to them. Yes.

  Sprockets are respectively attached to the end portions of the intake / exhaust camshafts 42 and 44 and the crankshaft 13 on the first cam cap 52 side, and the timing chain 15 is stretched around these sprockets. Therefore, when the crankshaft 13 rotates, the rotation is transmitted to the intake / exhaust camshafts 42 and 44 via the sprockets and the timing chain 15. In place of the sprocket and the timing chain 15, a timing pulley and a timing belt may be used.

  In order to transmit the rotation of the intake / exhaust camshafts 42, 44 to the intake / exhaust valves 34, 35, a valve lifter 55 is assembled to the upper end of each valve stem 36 of the intake / exhaust valves 34, 35. Each valve lifter 55 is disposed below the intake / exhaust cams 43, 45. When the intake / exhaust cam shafts 42, 44 rotate, the valve lifter 55 is pressed by the intake / exhaust cams 43, 45, whereby the intake / exhaust valves 34, 35 are pushed down. By this depression, the intake / exhaust ports 32 and 33 are opened (opened state). As described above, the valve opening / closing mechanism provided in the cylinder head 20A is of the direct acting type (valve lifter type), and the valve opening / closing mechanism is disposed in the subassembly 40A.

  A fuel injection valve for injecting fuel is attached to the intake passage corresponding to each cylinder 11. The fuel injected by the fuel injection valve is mixed with the intake air introduced into the combustion chamber 14 through the intake port 32 and becomes an air-fuel mixture. Note that the fuel may be directly injected into the combustion chamber 14 from the fuel injection valve without using the intake port 32.

  A spark plug 39 is attached to the cylinder head body 31 corresponding to each cylinder 11. The air-fuel mixture described above is ignited by the electric spark of the spark plug 39 and explodes / combusts. The piston 12 is reciprocated by the high-temperature and high-pressure combustion gas generated at this time, the crankshaft 13 is rotated, and the driving force (output torque) of the engine is obtained. The combustion gas is discharged to the exhaust passage through the exhaust port 33.

  In the cylinder head 20A, as shown in FIG. 4, the first cam carrier 41 described above and various components such as a valve opening / closing mechanism incorporated therein (intake / exhaust cam shafts 42, 44, first cam cap 48). , 52, 54, bolts 49, 53, etc.) constitute a sub-assembly 40A. Further, as shown in FIG. 5, a main assembly 30 is constituted by the cylinder head body 31 and various parts (intake / exhaust valves 34, 35, retainer 37, valve spring 38, etc.) incorporated therein.

  Next, the cylinder head 20B will be described with reference to FIG. 1B and FIGS.

  The cylinder head 20 </ b> B includes a main assembly 30 that occupies most of the cylinder head 20 </ b> B and a sub-assembly 40 </ b> B that is selectively attached on the main assembly 30. A major difference from the cylinder head 20A described above is that in the cylinder head 20B, the subassembly 40B is attached to the cylinder head body 31 instead of the subassembly 40A. As the main assembly 30, one having the same configuration as that in the cylinder head 20A is used.

  As shown in FIGS. 6 to 8, the sub assembly 40 </ b> B includes a second cam carrier 61 serving as a second support base disposed on the upper side of the cylinder head body 31. The second cam carrier 61 is fastened to the cylinder head body 31 by fastening parts such as bolts. The second cam carrier 61 lifts the intake / exhaust valves 34, 35 in a direction (opening direction, substantially downward in FIG. 6) to open the intake / exhaust ports 32, 33 against the valve spring 38 and the like. A valve opening / closing mechanism is provided. As this valve opening / closing mechanism, a rocker arm type (roller arm type) is employed, which is different from the above-described sub assembly 40A. The subassembly 40B has substantially the same configuration as the subassembly 40A described above except for the valve opening / closing mechanism.

  The valve opening / closing mechanism will be described. As shown in FIGS. 6 to 8, the second cam carrier 61 is arranged in the cylinder arrangement direction (the left-right direction in FIG. 7), and a plurality of locations corresponding to the respective cylinders 11 include the second A bearing portion 62 is provided. The structure for supporting the intake / exhaust camshafts 42 and 44 is substantially the same as that of the above-described subassembly 40A. Specifically, in each second bearing portion 62, concave portions 63 and 66 are formed substantially above the intake / exhaust valves 34 and 35. An intake camshaft 42 having an intake cam 43 is rotatably supported by a second bearing portion 62 and a second cam cap 64 in a recess 63. The second cam cap 64 is fastened to the second bearing portion 62 by a bolt 65 with the shaft portion of the intake camshaft 42 covered from above. The exhaust cam shaft 44 having the exhaust cam 45 is rotatably supported by the second bearing portion 62 and the second cam cap 67 in the recess 66. The second cam cap 67 is fastened to the second bearing portion 62 by a bolt 68 with the shaft portion of the exhaust camshaft 44 covered from above. Note that one end portion (left end portion in FIG. 7) of each of the intake / exhaust cam shafts 42 and 44 is rotatably supported by a second cam cap 69 and a second bearing portion 62 common to them. Yes.

  In the sub-assembly 40B, the rotation of the intake / exhaust cam shafts 42, 44 is transmitted between the intake / exhaust cams 43, 45 and the upper ends of the valve stems 36 in order to transmit the rotation of the intake / exhaust cam shafts 42, 44 to the intake / exhaust valves 34, 35. The rocker arm 71 having the roller 72 is disposed so as to be swingable. Each roller 72 is disposed below the intake / exhaust cams 43 and 45. One end of each rocker arm 71 is positioned immediately above the intake / exhaust valves 34 and 35, and the other end is positioned directly above the lash adjuster 73.

  The lash adjuster 73 has a known structure in which the plunger 73b in the body 73a slides up and down by the compression reaction force and hydraulic pressure of the plunger spring, and the body 73a is fixed to the second cam carrier 61. Specifically, the body 73 a of the lash adjuster 73 is fixed to a protruding portion 62 a formed at the lower portion of the second bearing portion 62. The protruding portion 62 a is provided at a position of the second bearing portion 62 between the intake camshaft 42 and the exhaust camshaft 44, and protrudes toward the center side of the cylinder 11. The second bearing portion 62 of the second cam carrier 61 is different from the first bearing portion 46 of the first cam carrier 41 described above in that the protruding portion 62a for supporting the lash adjuster 73 is formed. Different.

  Since the lash adjuster 73 is provided in this way, the compression reaction force of the valve spring 38 is transmitted to one end of the rocker arm 71 via the intake / exhaust valves 34 and 35 and the lash adjuster 73 is pushed up. Force is transmitted to the other end of the rocker arm 71. The rocker arm 71 is pushed up by both transmissions, and the roller 72 is in contact with the intake and exhaust cams 43 and 45. When the intake / exhaust camshafts 42 and 44 rotate, the rocker arm 71 swings downward against the valve spring 38 with the head of the plunger 73b as a fulcrum. By this swinging, the intake / exhaust valves 34 and 35 are pushed down against the valve spring 38 and the like. By this depression, the intake / exhaust ports 32 and 33 are opened (opened state). As described above, the valve opening / closing mechanism provided in the cylinder head 20B is of the rocker arm type (roller arm type), and the valve opening / closing mechanism is disposed in the subassembly 40B.

  In the cylinder head 20B, as shown in FIG. 8, the above-described second cam carrier 61 and various components such as a valve opening / closing mechanism incorporated therein (intake / exhaust camshafts 42, 44, second cam cap 64). , 67, 69, lash adjuster 73, etc.) constitute sub-assembly 40B. The main assembly 30 has the same configuration as that of the cylinder head 20A described above, and as shown in FIG. 5, the cylinder head body 31 and various components (intake / exhaust valves 34, 35, The retainer 37, the valve spring 38, etc.).

  As described above, in this example, since two types of cylinder heads 20A and 20B are configured, the valve opening / closing mechanism employed when manufacturing the cylinder heads 20A and 20B is a direct acting type or a rocker arm type. Regardless, the structure shown in FIG. 5 is commonly used as the main assembly 30 including the cylinder head body 31. On the other hand, two types of subassemblies 40A and 40B are prepared in advance, and two types of subassemblies 40A and 40B are provided depending on whether the valve opening / closing mechanism provided in the cylinder head is a direct acting type or a rocker arm type. One of 40B is selected. Then, one of the selected sub-assemblies 40A and 40B is attached to the main assembly 30.

  Specifically, when a direct-acting type is employed as the valve opening / closing mechanism, a subassembly 40A including the first cam carrier 41 shown in FIG. 4 is selected as the subassembly. A valve lifter 55 is assembled to the upper end of the valve stem 36 of each of the intake / exhaust valves 34, 35. When the subassembly 40A is properly disposed on the cylinder head body 31 of the main assembly 30 shown in FIG. 5, the intake / exhaust camshafts 42, 44 are connected to the intake / exhaust valves 34, 44, as shown in FIG. The intake / exhaust cams 43, 45 are positioned substantially above 35 and contact the corresponding valve lifter 55. In this state, when the subassembly 40A is fastened to the cylinder head body 31 of the main assembly 30 by fastening parts such as bolts, the cylinder head 20A having a direct acting valve opening / closing mechanism is obtained.

  In the engine shown in FIG. 2 in which such a cylinder head 20 </ b> A is incorporated, when the intake camshaft 42 rotates, the rotation is transmitted to the intake valve 34. By this transmission, the intake valve 34 is pushed down against the valve spring 38 to open. Similarly, when the exhaust camshaft 44 rotates, the rotation is transmitted to the exhaust valve 35. By this transmission, the exhaust valve 35 is pushed down against the valve spring 38 to open.

  On the other hand, when a rocker arm type is employed as the valve opening / closing mechanism, the subassembly 40B including the second cam carrier 61 shown in FIG. 8 is selected as the subassembly. A rocker arm 71 is stretched over the valve stem 36 of each intake / exhaust valve 34, 35 and the corresponding lash adjuster 73. When the subassembly 40B is properly arranged on the cylinder head body 31 of the main assembly 30 shown in FIG. 5, the intake / exhaust camshafts 42, 44 are connected to the intake / exhaust valves 34, 44, as shown in FIG. The suction / exhaust cams 43 and 45 are positioned substantially above the contact 35 and contact the roller 72 of the corresponding rocker arm 71. In this state, when the subassembly 40B is fastened to the cylinder head main body 31 of the main assembly 30 by fastening parts such as bolts, the cylinder head 20B having a rocker arm type valve opening / closing mechanism is obtained.

  In the engine shown in FIG. 6 in which such a cylinder head 20 </ b> B is incorporated, when the intake camshaft 42 rotates, the rotation is transmitted to the intake valve 34 via the rocker arm 71. By this transmission, the intake valve 34 is pushed down against the valve spring 38 to open. Similarly, when the exhaust camshaft 44 rotates, the rotation is transmitted to the exhaust valve 35 via the rocker arm 71. By this transmission, the exhaust valve 35 is pushed down against the valve spring 38 to open.

  Thereby, the following effects are obtained.

  That is, what is equivalent to a conventional cylinder head is divided into a cylinder head main body 31 and cam carriers (first cam carrier 41 and second cam carrier 61). The main assembly 30 is configured by assembling the intake / exhaust valves 34 and 35, the valve spring 38, and the like to the cylinder head body 31. The first cam carrier 41 is provided with a direct-acting valve opening / closing mechanism to constitute a subassembly 40A, while the second cam carrier 61 is provided with a rocker arm type valve opening / closing mechanism to constitute a subassembly 40B. . Then, while sharing the main assembly 30 including the cylinder head body 31, one of the two types of sub-assemblies 40A and 40B is selected and attached to the main assembly 30 according to the difference in the valve opening / closing mechanism employed. 20A or cylinder head 20B is manufactured.

  Therefore, by sharing the main assembly 30 as described above, it is possible to manufacture the cylinder head 20A having a direct-acting valve opening / closing mechanism by changing fewer parts. It is also possible to manufacture the cylinder head 20B having the same. As a result, it is possible to suppress the investment for newly increasing the production facilities (factories, machines, etc.) of the cylinder heads 20A and 20B, and to reduce the cost of the cylinder heads 20A and 20B.

  In the above, when the valve characteristic variable function is not provided, it has been described that the main assembly of the cylinder head is shared regardless of the difference in the valve opening / closing mechanism. The main assembly of the cylinder head can be shared depending on the necessity of such a variable function of valve characteristics. Next, this will be described with reference to FIGS.

  A difference from the above-described example is that a cylinder head 20A and a cylinder head 20C are set as cylinder heads, as shown in FIGS. 9A and 9B. The cylinder head 20C shown in FIG. 9B is a cylinder head in which a valve characteristic varying device 100 described later is incorporated in the cylinder head 20B shown in FIG. The cylinder head 20A shown in FIG. 9 (A) has the same configuration as that shown in FIG. 1 (A) of the above-described example, and includes the main assembly 30 and the subassembly 40A. As the valve opening / closing mechanism of the cylinder head 20A, a direct acting type (valve lifter type) is employed (see FIGS. 2 to 5).

  The cylinder head 20C will be described with reference to FIG. 9B and FIGS.

  The cylinder head 20 </ b> C includes a main assembly 30 that occupies most of the cylinder head 20 </ b> C, and a subassembly 40 </ b> C that is selectively mounted on the main assembly 30. A major difference from the cylinder head 20B described above is that, in the cylinder head 20C, the subassembly 40C is attached to the cylinder head body 31 as a third support base instead of the subassembly 40B. As the main assembly 30, one having the same configuration as that in the cylinder head 20A (cylinder head 20B) is used.

  As shown in FIGS. 10 to 12, the subassembly 40 </ b> C includes a third cam carrier 81 as a third support base disposed on the upper side of the cylinder head body 31. The third cam carrier 81 is fastened to the cylinder head body 31 by fastening parts such as bolts. The third cam carrier 81 lifts the intake / exhaust valves 34, 35 in a direction (opening direction, substantially downward in FIG. 10) to open the intake / exhaust ports 32, 33 against the valve spring 38 and the like. A valve opening / closing mechanism is provided. As this valve opening / closing mechanism, a rocker arm type (roller arm type) similar to that of the sub-assembly 40B described above is employed. In addition, the third cam carrier 81 is assembled with a valve characteristic varying device 100 described later.

  In the cylinder arrangement direction of the third cam carrier 81 (left and right direction in FIG. 11), the same number (here, a pair) of third bearing portions 82 is provided for each cylinder 11 at a plurality of locations corresponding to each cylinder 11. ing. In each third bearing portion 82, a recess 87 is formed substantially above the exhaust valve 35, and the exhaust camshaft 44 having the exhaust cam 45 is connected to the third bearing portion 82 and the third cam cap in this recess 87. 88 and is rotatably supported. The third cam cap 88 is fastened to the third bearing portion 82 by a bolt 89 with the shaft portion of the exhaust camshaft 44 covered from above. This point is the same as the subassembly 40B of the cylinder head 20B described above.

  On the other hand, in the cylinder head 20 </ b> C, the intake cam 43 does not directly contact the roller 72 of the rocker arm 71, but indirectly contacts the roller 72 via a valve characteristic varying device 100 described later. Therefore, the position of the intake camshaft 42 in the subassembly 40C is different from the position of the intake camshaft 42 in the subassembly 40B (see FIG. 8). That is, in the subassembly 40B, the intake camshaft 42 is positioned substantially above the upper end (roller 72) of the valve stem 36. However, in the subassembly 40C, the intake camshaft is secured in order to secure a space for incorporating the valve characteristic varying device 100. The shaft 42 is located at a position slightly away from the upper end (roller 72) of the valve stem 36 in the width direction of the third cam carrier 81 (left-right direction in FIG. 12).

  In order to arrange the intake camshaft 42 at such a location, in the subassembly 40C, a recess 83 for supporting the intake camshaft 42 is provided in each of the third bearing portions 82 of the third cam carrier 81. The second cam carrier 61 is provided at a location shifted in the width direction with respect to the concave portion 63. The intake camshaft 42 is rotatably supported by the third bearing portion 82 and the third cam cap 85 in the recess 83. The third cam cap 85 is fastened to the third bearing portion 82 by a bolt 86 with the shaft portion of the intake camshaft 42 covered from above.

  Further, in the cylinder head 20C, in order to transmit the rotation of the intake / exhaust cam shafts 42, 44 to the intake / exhaust valves 34, 35, between the intake / exhaust cams 43, 45 and the upper ends of the valve stems 36 are provided. The rocker arm 71 having the roller 72 is disposed so as to be swingable. One end of each rocker arm 71 is positioned immediately above the intake / exhaust valves 34 and 35, and the other end is positioned directly above the lash adjuster 73. The body 73 a of the lash adjuster 73 is fixed to a protruding portion 82 a formed at the lower portion of the third bearing portion 82. The roller 72 of the rocker arm 71 that transmits the rotation of the exhaust camshaft 44 to the exhaust valve 35 is disposed below the exhaust cam 45. These points are the same as those of the subassembly 40B of the cylinder head 20B. On the other hand, in the subassembly 40C, unlike the subassembly 40B, the roller 72 of the rocker arm 71 that transmits the rotation of the intake camshaft 42 to the intake valve 34 is used for the output arms 112 and 113 of the valve characteristic varying device 100 described later. It is arranged below. As described above, the valve opening / closing mechanism provided in the cylinder head 20C is of the rocker arm type (roller arm type), and the valve opening / closing mechanism is disposed in the subassembly 40C.

  Next, the variable valve characteristic device 100 incorporated in the subassembly 40C will be described.

  The variable valve characteristic device 100 is a device for changing at least one of the operating angle and the maximum lift amount of the engine valve (intake / exhaust valves 34, 35) as valve characteristics. In this example, the variable valve characteristic device 100 is used for continuously changing the operating angle and the maximum lift amount of the intake valve 34. Here, as shown in FIG. 13, the operating angle of the intake valve 34 refers to the rotation of the intake cam 43 (expressed by the crank angle in FIG. 13) from the valve opening timing IVO to the valve closing timing IVC. Angle range. The maximum lift amount is a movement amount of the intake valve 34 when the intake valve 34 is moved (lifted) to the lowermost part of the movable range when the valve is opened. These working angles and the maximum lift amount are changed in synchronization with each other by the valve characteristic varying device 100. For example, the smaller the working angle, the smaller the maximum lift amount. As the operating angle decreases, the valve opening timing IVO and the valve closing timing IVC of the intake valve 34 approach each other, the valve opening period becomes shorter, and the intake air amount per cylinder 11 decreases. Thus, the valve operating mechanism of the intake valve 34 is a variable valve operating mechanism having a function of changing valve characteristics. On the other hand, the valve characteristic varying device 100 is not provided for the valve operating mechanism of the exhaust valve 35.

  As shown in FIGS. 10 to 12, the variable valve characteristic device 100 includes an intermediate drive mechanism 110 for each cylinder 11, and a support pipe 101, a control shaft 102, and an actuator that are common to all the intermediate drive mechanisms 110. 103. The support pipe 101 is disposed so as to extend in the cylinder arrangement direction. In each third bearing portion 82, a recess 84 is formed substantially above the intake valve 34, and the support pipe 101 is sandwiched between the third bearing portion 82 and the third cam cap 85 in the recess 84. It is fixed. Therefore, the intake camshaft 42 and the support pipe 101 are supported by the third bearing portion 82 by the common third cam cap 85. Note that one end of each of the intake / exhaust camshafts 42 and 44 and the support pipe 101 (the left end in FIG. 11) is supported by a third cam cap 91 and a third bearing portion 82 common to them. ing.

  Note that the direction in which the support pipe 101 extends is referred to as an “axial direction” when it is not necessary to distinguish between them, and is referred to as an arrow X direction or an arrow Y direction when it is necessary to distinguish. An arrow X direction is a direction approaching the above-described timing chain 15 (a direction away from the actuator 103), and is a direction in which the operating angle of the intake cam 43 is reduced. An arrow Y direction is a direction away from the timing chain 15 (a direction approaching the actuator 103), and is a direction in which the operating angle is increased.

  Since the support pipe 101 is fixed to the third cam carrier 81 as described above, movement in the axial direction is restricted and rotation is also impossible. The control shaft 102 is slidably inserted into the support pipe 101. The actuator 103 includes an electric motor and a conversion mechanism that converts the rotation of the electric motor into a linear motion and transmits the linear motion to the control shaft 102. The control shaft 102 is reciprocated in the axial direction by transmission of this linear motion.

  Each intermediate drive mechanism 110 is disposed between the intake cam 43 and the intake valve 34. As shown in FIGS. 14 to 16, each mediation drive mechanism 110 includes an input arm 111 and a pair of output arms 112 and 113 arranged on both sides in the axial direction. The input arm 111 and the output arms 112 and 113 for each of the mediation drive mechanisms 110 are connected to each other at their opposite ends by fitting. Further, the input arm 111 and the output arms 112 and 113 for each intermediate drive mechanism 110 are disposed between the pair of third bearing portions 82 and 82 for each cylinder 11 in the third cam carrier 81, and extend in the axial direction. The displacement is regulated by both third bearing portions 82 and 82.

  A pair of support pieces 116, 116 project from the outer peripheral surface of each input arm 111, and a roller 117 is pivotally supported on both support pieces 116, 116. On the other hand, each of the output arms 112 and 113 includes a base circle 121 and a nose 122 protruding from the outer peripheral surface of the base circle 121. Each nose 122 has a cam surface 122a that curves in a concave shape.

  A power transmission slider 114 is disposed between the support pipe 101 and the input / output arms 111 to 113. The slider 114 is supported on the support pipe 101 so as to be rotatable and displaceable in the axial direction. In order to connect the slider 114 outside the support pipe 101 to the control shaft 102 in the support pipe 101 so that power can be transmitted, a circumferential groove 124 extending in the circumferential direction is formed on the inner wall of the slider 114. Further, in the support pipe 101, a long hole 125 extending in the axial direction is formed at a location sandwiched between the adjacent third bearing portions 82 and 82. A columnar locking pin 127 is disposed at a location where the circumferential groove 124 and the long hole 125 intersect, and an inner end portion thereof (a lower end portion in FIG. 13) is inserted into the pin hole 126 of the control shaft 102. . Further, a bush 128 is locked to an outer end portion (upper end portion in FIG. 13) of the locking pin 127 located in the circumferential groove 124. The bush 128 may be provided integrally with the locking pin 127.

  Therefore, as described above, the support pipe 101 is fixed to the third cam carrier 81, but as the control shaft 102 moves in the axial direction, the locking pin 127 moves in the long hole 125. The slider 114 can be displaced in the axial direction via the bush 128 and the locking pin 127. Further, since the slider 114 itself is engaged with the bush 128 and the locking pin 127 by the circumferential groove 124 extending in the circumferential direction, the axial position is determined by the bush 128 and the locking pin 127. However, it can rotate about the axis.

  In order to transmit power between the input arm 111 and the slider 114, a helical spline 111a twisted in the clockwise direction toward the one output arm 112 side is formed on the inner peripheral surface of the input arm 111. Correspondingly, a helical spline 114a that is twisted in the same direction is formed in an intermediate portion of the outer peripheral surface of the slider 114 in the axial direction, and meshed with the helical spline 111a described above.

  Further, in order to transmit power between the output arms 112 and 113 and the slider 114, the inner peripheral surfaces of the output arms 112 and 113 are opposite to the helical spline 111a of the input arm 111, that is, the input arms. Helical splines 112b and 113c that are twisted in the counterclockwise direction as the distance from 111 to the one output arm 112 side is formed. Correspondingly, helical splines 114b and 114c twisted in the same direction are formed at both ends in the axial direction of the outer peripheral surface of the slider 114, and these mesh with the helical splines 112b and 113c described above.

  Thus, the helical splines 111a and 114a and the helical splines 112b, 113c, 114b, and 114c are twisted in the opposite directions. Therefore, when the slider 114 rotates while displacing in the same direction in conjunction with the axial movement of the control shaft 102, torsional forces in opposite directions are applied to the input arm 111 and the output arms 112 and 113, respectively. Is done. As a result, the relative phase difference between the input arm 111 and the output arms 112 and 113 changes. In addition, the relative phase difference between the input / output arms 111 to 113 is determined by the slider 114 in the direction indicated by the arrow X (the working angle is changed by setting the twist direction of the helical splines (111a, 112b, 113c), (114a, 114b, 114c)). It becomes smaller as it is displaced in the direction of decreasing).

  As shown in FIGS. 17A and 17B, the roller 117 of each intermediary drive mechanism 110 is in contact with the intake cam 43 of the intake camshaft 42, and the intake cam 43 as the intake camshaft 42 rotates. Is applied to the roller 117.

  The roller 72 of each rocker arm 71 in the cylinder head body 31 is located below the base circle 121 of the output arms 112 and 113. One end (left side in FIG. 17) of the rocker arm 71 is in contact with the upper end of the valve stem 36 of the intake valve 34, and the other end (right side in FIG. 17) is the plunger of the lash adjuster 73. 73b is in contact. By these contacts, the compression reaction force of the valve spring 38 is transmitted to one end portion of the rocker arm 71 via the intake valve 34, and the push-up force of the lash adjuster 73 is transmitted to the other end portion of the rocker arm 71. . The rocker arm 71 is pushed up by both transmissions, and the roller 72 is in contact with the base circle 121 or the nose 122 of the output arms 112 and 113.

  In FIG. 14A, reference numeral 118 denotes a projecting piece provided at a location different from the support piece 116 on the outer peripheral surface of the input arm 111. Further, reference numeral 129 in the figure attaches the input arm 111 in the direction opposite to the swinging direction of the input arm 111 by the depression of the intake cam 43 (clockwise direction in FIG. 17A) through the protruding piece 118. It is a lost motion spring. In the lost motion spring 129, the roller 117 comes into contact with the base circle portion 121 and tries to rotate the rotation biasing force (the support piece 116 in the clockwise direction in FIG. 17A) due to the compression reaction force of the valve spring 38. Even when the force) becomes very small, the roller 117 is reliably pressed against the intake cam 43 to suppress a problem that the roller 117 is separated from the intake cam 43.

  In the cylinder head 20C, as shown in FIG. 12, the above-described third cam carrier 81 and various components such as a valve opening / closing mechanism incorporated therein (intake / exhaust camshafts 42, 44, third cam cap 85). , 88, 91, bolts 86, 89, lash adjuster 73, etc.) and valve characteristic varying device 100 constitute sub-assembly 40C. The main assembly 30 has the same configuration as that of the cylinder head 20A described above, and as shown in FIG. 5, the cylinder head body 31 and various components (intake / exhaust valves 34, 35, The retainer 37, the valve spring 38, etc.).

  As described above, in this example, since two types of cylinder heads 20A and 20C are respectively configured, the cylinder head main body 31 can be mounted regardless of whether or not the variable function of the valve characteristics is necessary when manufacturing the cylinder heads 20A and 20C. The main assembly 30 including the structure shown in FIG. 5 is commonly used. On the other hand, two types of subassemblies 40A and 40C are prepared in advance, and one of the two types of subassemblies 40A and 40C is selected according to the necessity of the variable function of the valve characteristics. Then, one of the selected sub-assemblies 40A and 40C is attached to the main assembly 30.

  Specifically, when the variable function of the valve characteristic is unnecessary, the subassembly 40A including the first cam carrier 41 shown in FIG. 4 is selected as the subassembly. A valve lifter 55 is assembled to the upper end of the valve stem 36 of each of the intake / exhaust valves 34, 35. When the subassembly 40A is properly disposed on the cylinder head body 31 of the main assembly 30 shown in FIG. 5, the intake / exhaust camshafts 42, 44 are connected to the intake / exhaust valves 34, 44, as shown in FIG. The intake / exhaust cams 43, 45 are positioned substantially above 35 and contact the corresponding valve lifter 55. In this state, when the sub-assembly 40A is fastened to the cylinder head body 31 of the main assembly 30 by fastening parts such as bolts, the cylinder head 20A that does not have a variable function of valve characteristics is obtained. The cylinder head 20A is a cylinder head having a direct-acting valve opening / closing mechanism.

  In the engine shown in FIG. 2 in which such a cylinder head 20 </ b> A is incorporated, when the intake camshaft 42 rotates, the rotation is transmitted to the intake valve 34. By this transmission, the intake valve 34 is pushed down against the valve spring 38 to open. Similarly, when the exhaust camshaft 44 rotates, the rotation is transmitted to the exhaust valve 35. By this transmission, the exhaust valve 35 is pushed down against the valve spring 38 to open.

  On the other hand, when the variable function of the valve characteristic is required, the subassembly 40C including the third cam carrier 81 shown in FIG. 12 is selected as the subassembly. A rocker arm 71 is stretched over the valve stem 36 of each intake / exhaust valve 34, 35 and the corresponding lash adjuster 73. When the subassembly 40C is properly disposed on the cylinder head body 31 of the main assembly 30 shown in FIG. 5, the exhaust camshaft 44 is positioned substantially above the exhaust valve 35, as shown in FIG. The exhaust cam 45 contacts the roller 72 of the corresponding rocker arm 71. Further, each mediation drive mechanism 110 of the variable valve characteristic device 100 is positioned substantially above the intake valve 34, and the base circle 121 or nose 122 of each output arm 112, 113 contacts the roller 72 of the corresponding rocker arm 71. In this state, when the subassembly 40C is fastened to the cylinder head body 31 of the main assembly 30 by fastening parts such as bolts, the cylinder head 20C having a variable function of the valve characteristics is obtained. The cylinder head 20C is a cylinder head having a rocker arm type valve opening / closing mechanism.

  In the engine shown in FIG. 10 incorporating such a cylinder head 20 </ b> C, when the exhaust camshaft 44 rotates, the rotation is transmitted to the exhaust valve 35 via the rocker arm 71. By this transmission, the exhaust valve 35 is pushed down against the valve spring 38 to open. About this point, it is the same as that of the engine in which the cylinder head 20A mentioned above was incorporated.

  Further, when the intake camshaft 42 rotates, the rotation is transmitted to the intake valve 34 through the valve characteristic varying device 100. At this time, in the variable valve characteristic device 100, if the control shaft 102 is not driven by the actuator 103, the input arm 111 swings with the control shaft 102 as a fulcrum as the intake cam 43 rotates. This swing is transmitted to the output arms 112 and 113 via the slider 114, and the output arms 112 and 113 swing. The rocker arms 71 corresponding to the swinging output arms 112 and 113 are swung, and the intake valve 34 is pushed down against the valve spring 38 to open.

  For example, FIGS. 17A and 17B show the state of the mediation drive mechanism 110 when the actuator 103 has moved the control shaft 102 in the direction indicated by the arrow Y in FIG. The slider 114 is located at the end in the arrow Y direction in the movable range. At this time, the relative phase difference between the input arm 111 and the output arms 112 and 113 is maximized, and the operating angle of the intake cam 43 is maximized.

  In particular, FIG. 17A shows a state in which the intake cam 43 is in contact with the roller 117 of the mediation drive mechanism 110 at the base circle 43a. In this state, a portion close to the nose 122 in the base circular portion 121 of both the output arms 112 and 113 is in contact with the roller 72 of the rocker arm 71. For this reason, the intake valve 34 is closed (the lift amount is “0”).

  When the intake camshaft 42 rotates in the direction indicated by the arrow, in the intermediate drive mechanism 110, the roller 117 is pushed down by the nose 43b of the intake cam 43, and the input arm 111 swings downward. This swing is transmitted to the output arms 112 and 113 via the slider 114, and the output arms 112 and 113 swing downward. As the output arms 112 and 113 swing, the cam surface 122a of the nose 122 immediately contacts the roller 72 of the rocker arm 71, and almost the entire range of the cam surface 122a is used as shown in FIG. Then, the roller 72 is pushed down. By this depression, the rocker arm 71 swings downward with the head of the plunger 73b of the lash adjuster 73 as a fulcrum, greatly depressing the intake valve 34, and greatly opening the intake valve 34. The maximum lift amount becomes the largest, and the amount of air flowing into the combustion chamber 14 from the intake port 32 becomes the maximum.

  When changing the valve characteristics, if the control shaft 102 is moved in the direction of arrow X in FIG. 11 by the actuator 103, the movement is transmitted to the slider 114 on the support pipe 101, and the slider 114 is displaced in the same direction while rotating. To do. As the slider 114 rotates, torsional forces in opposite directions are applied to the input arm 111 and the output arms 112 and 113, and as indicated by phantom lines in FIG. The relative phase difference 113 changes. This relative phase difference becomes smaller as the displacement amount of the slider 114 in the arrow X direction becomes larger.

  When the base circle portion 43 a of the intake cam 43 contacts the roller 117 of the mediation drive mechanism 110, the contact portion of the base circle portion 121 of the output arms 112 and 113 with the roller 72 of the rocker arm 71 moves away from the nose 122. For this reason, even if the output arms 112 and 113 swing, the roller 72 of the rocker arm 71 continues to contact the base circle 121 without contacting the cam surface 122a of the nose 122 for a while.

  Thereafter, the cam surface 122a pushes down the roller 72, and the rocker arm 71 is swung downward with the head of the plunger 73b of the lash adjuster 73 as a fulcrum, but the cam surface 122a is initially separated from the nose 122. The range of use becomes smaller. As a result, the rocking angle of the rocker arm 71 is reduced. Thus, the intake valve 34 opens the intake port 32 at a smaller working angle than at the maximum. As the intake valve 34 opens, the amount of air flowing into the combustion chamber 14 from the intake port 32 decreases according to the amount of displacement of the slider 114 in the arrow X direction.

  In this way, by adjusting the axial position of the slider 114 through the control shaft 102 by the actuator 103, the relative position in the axial direction of the input arm 111 and the output arms 112 and 113 with respect to the slider 114 can be changed. As shown in FIG. 13, the operating angle of the intake cam 43 and the maximum lift amount of the intake valve 34 can be continuously adjusted.

  As described above, the following effects can be obtained.

  That is, what is equivalent to a conventional cylinder head is divided into a cylinder head main body 31 and cam carriers (first cam carrier 41 and third cam carrier 81). The main assembly 30 is configured by assembling the intake / exhaust valves 34 and 35, the valve spring 38, and the like to the cylinder head body 31. The sub-assembly 40A is configured by rotatably supporting the intake / exhaust camshafts 42, 44 on the first cam carrier 41, while the third cam carrier 81 has the intake / exhaust camshafts 42, 44, etc. In addition, by incorporating the valve characteristic variable device 100, the subassembly 40C is configured. In addition, a direct-acting valve opening / closing mechanism is provided in the subassembly 40A, while a rocker arm type valve opening / closing mechanism is provided in the subassembly 40C. Then, while sharing the main assembly 30 including the cylinder head body 31, one of the two types of subassemblies 40A and 40C is selected and attached to the main assembly 30 in accordance with the necessity of the variable function of the valve characteristics. The head 20A or the cylinder head 20C is manufactured.

  Therefore, by sharing the main assembly 30 as described above, it is possible to manufacture the cylinder head 20A that does not have the variable function of the valve characteristics only by changing fewer parts, and the cylinder head 20C that includes the cylinder head 20C. You can also. As a result, it is possible to suppress investment for newly increasing the production facilities (factories, machines, etc.) of the cylinder heads 20A, 20C, and to reduce the cost of the cylinder heads 20A, 20C.

  As the valve opening / closing mechanism, the direct acting valve opening / closing mechanism is less expensive than the rocker arm type valve opening / closing mechanism. Therefore, as described above, when the variable function of the valve characteristic is unnecessary, a cylinder head that does not have the variable function of the valve characteristic can be made cheaper by adopting a direct-acting valve open / close mechanism as the valve open / close mechanism. Can be manufactured.

  In the above two examples, when two types of cylinder heads are set as the cylinder head, it has been described that the main assembly of the cylinder head is shared (see FIG. 1 and FIG. 9). The same applies when the cylinder head is set.

  As an example, as shown in FIG. 18, three types of cylinder heads 20A, 20B, and 20C can be set as cylinder heads. A cylinder head 20A shown in FIG. 18A has the same configuration as that shown in FIGS. 1A and 9A in the above-described example. The cylinder head 20B shown in FIG. 18B has the same configuration as that shown in FIG. A cylinder head 20C shown in FIG. 18C has the same configuration as that shown in FIG. 9B of the above-described example.

  As described above, three types of subassemblies 40A, 40B, and 40C are prepared in advance as subassemblies that constitute the cylinder head, together with the main assembly 30 that is shared by any of the cylinder heads 20A, 20B, and 20C. Then, one of the three types of subassemblies 40A, 40B, and 40C is selected according to the necessity of the variable function of the valve characteristics of the intake valve 34 and the valve opening / closing mechanism provided in the cylinder head. Any of the selected sub-assemblies 40A, 40B, and 40C is attached to the main assembly 30 shown in FIG.

  Specifically, when a variable function of the valve characteristic is necessary, the subassembly 40C shown in FIG. 12 is selected as the subassembly.

  On the other hand, when the variable function of the valve characteristic is unnecessary, the subassembly 40A shown in FIG. 4 or the subassembly 40B shown in FIG. 8 is selected as the subassembly. Here, when a direct acting type is adopted as the valve opening / closing mechanism, the sub-assembly 40A shown in FIG. 4 is selected. On the other hand, when a rocker arm type is employed as the valve opening / closing mechanism, the subassembly 40B shown in FIG. 8 is selected.

  Since the main assembly 30 is shared as described above, it is possible to cope with various types of cylinder heads 20A, 20B, and 20C by changing fewer parts. , 20C manufacturing equipment (factories, machines, etc.) can be reduced, and as a result, the cost of the cylinder heads 20A, 20B, 20C can be reduced.

  In the above example, the variable valve characteristic device 100 is provided only in the intake valve 34. However, the present invention is not limited to this, and the variable valve characteristic device 100 can be provided in the exhaust valve 35 as well. Further, the variable valve characteristic device 100 can be provided on both the intake and exhaust valves 34 and 35.

  Further, in addition to the variable valve characteristic device 100, a variable valve timing device can be provided in the cylinder head. In this case, the variable valve characteristic device can be provided in the subassembly and can be disposed between the intake camshaft 42 and its sprocket.

  In the above, an example in which the present invention is applied to a cylinder head of an in-line four-cylinder gasoline engine has been described. However, the present invention is not limited to this example. The same can be applied. Furthermore, the present invention is not limited to gasoline engines, and can be applied to cylinder heads of other internal combustion engines such as diesel engines.

It is the schematic which shows one Embodiment of the cylinder head to which this invention is applied. It is a partial longitudinal cross-sectional view of the engine in which the cylinder head of FIG. It is a top view of the engine in which the cylinder head of Drawing 1 (A) was assembled. It is a longitudinal cross-sectional view of the subassembly in FIG. FIG. 3 is a partial longitudinal sectional view of the main assembly in FIG. 2. It is a partial longitudinal cross-sectional view of the engine in which the cylinder head of FIG. 1 (B) was assembled. It is a top view of the engine in which the cylinder head of Drawing 1 (B) was assembled. It is a longitudinal cross-sectional view of the subassembly in FIG. It is the schematic which shows other embodiment of the cylinder head to which this invention is applied. FIG. 10 is a partial longitudinal sectional view of an engine in which the cylinder head of FIG. 9B is assembled. It is a top view of the engine in which the cylinder head of Drawing 9 (B) was assembled. It is a longitudinal cross-sectional view of the subassembly in FIG. It is a characteristic view which shows the change aspect of a working angle and the maximum lift amount by a valve characteristic variable apparatus. It is a perspective view which shows a mediation drive mechanism. It is a top view which shows the slider etc. of a mediation drive mechanism. It is sectional drawing which shows a mediation drive mechanism. It is operation | movement explanatory drawing of a mediation drive mechanism. It is the schematic which shows other embodiment of the cylinder head to which this invention is applied.

Explanation of symbols

10 cylinder block 11 cylinder (cylinder)
13 Crankshaft 20A, 20B, 20C Cylinder head 30 Main assembly 31 Cylinder head main body 34 Intake valve 35 Exhaust valve 38 Valve spring 40A, 40B, 40C Subassembly 41 First cam carrier 42 Intake camshaft 43 Intake cam 44 Exhaust camshaft 45 Exhaust cam 46 First bearing portion 55 Valve lifter 61 Second cam carrier 62 Second bearing portion 71 Rocker arm 72 Roller 81 Third cam carrier 82 Third bearing portion 100 Valve characteristic variable device 101 Support pipe 102 Control shaft 110 Mediation drive mechanism 111 Input Arm 111a Helical spline 112, 113 Output arm 112b, 113c Helical spline 114 Slider 114a, 114b, 114c Helicopter Calspline

Claims (3)

A cylinder head of an internal combustion engine provided with an engine valve, a valve spring that urges the engine valve in the valve closing direction, and a camshaft that drives the engine valve in the valve opening direction against the valve spring,
A cylinder head body in which the engine valve and the valve spring are assembled;
A first support base rotatably supported by the camshaft so that the camshaft cam directly pushes down the engine valve; and the camshaft cam pushes the engine valve indirectly through the rocker arm. A cylinder head for an internal combustion engine, comprising: a support base portion that is selected from a second support base portion on which a camshaft is rotatably supported, and is attached to the cylinder head body. A cylinder head of an internal combustion engine provided with an engine valve, a valve spring that urges the engine valve in the valve closing direction, and a camshaft that drives the engine valve in the valve opening direction against the valve spring,
A cylinder head body in which the engine valve and the valve spring are assembled;
A first support base rotatably supported by the camshaft so that the camshaft cam directly pushes down the engine valve; and the camshaft cam pushes the engine valve indirectly through the rocker arm. The camshaft is rotatably supported, and is selected from a third support base portion on which a valve characteristic variable device for changing the valve characteristic of the engine valve is assembled, and is attached to the cylinder head body. A cylinder head for an internal combustion engine, comprising a support base. A cylinder head of an internal combustion engine provided with an engine valve, a valve spring that urges the engine valve in the valve closing direction, and a camshaft that drives the engine valve in the valve opening direction against the valve spring,
A cylinder head body in which the engine valve and the valve spring are assembled;
A first support base rotatably supported by the camshaft so that the camshaft cam directly pushes down the engine valve; and the camshaft cam pushes the engine valve indirectly through a rocker arm. A second support base portion rotatably supported by the shaft; and the camshaft rotatably supported so that the cam of the camshaft pushes the engine valve indirectly through the rocker arm; and the valve of the engine valve A cylinder for an internal combustion engine, comprising: a support base part attached to the cylinder head body, and comprising any one selected from a third support base part to which a variable valve characteristic device for changing characteristics is assembled. head.

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