JP2005299538A - Variable valve operating device for internal combustion engine - Google Patents

Abstract

The present invention provides a variable valve operating apparatus in which a valve closing timing can be made larger than a valve opening timing by a single rocker arm mechanism, and variation in operation among cylinders can be easily adjusted.
A rocker arm mechanism 19 that opens and closes a valve 5 includes a first arm 25 that is swingably supported by a rocker shaft 11 and a first arm 25 that is driven by a cam 15 and swings around the rocker shaft side as a fulcrum. A third arm 45 that is swingably provided on the two arms 35 and the support shaft 13 disposed in the vicinity of the rocker shaft and drives the first arm by changing the cam phase by the posture change caused by the fulcrum movement of the second arm. And a variable mechanism 44 for displacing the fulcrum of the second arm, and the cam phase is variable by a single rocker arm mechanism. In addition, holding members 70a and 70b for holding the intake and exhaust rocker shafts 11 and 12 and the support shaft and modularizing the rocker arm mechanism are provided, and the rocker arm mechanism is fixed to the cylinder head 1 by the holding member. The configuration makes it easier to adjust the variation between cylinders.
[Selection] Figure 1

Description

  The present invention relates to a variable valve operating apparatus for an internal combustion engine that can vary the drive phase of an intake or exhaust valve.

  Many engines (internal combustion engines) installed in automobiles are equipped with variable valve gears for reasons such as engine exhaust gas countermeasures and fuel consumption reduction, and the intake and exhaust valve phases ( The opening / closing timing is changed.

Such a variable valve device has a reciprocating cam structure in which the phase of the cam formed on the camshaft is temporarily replaced with a reciprocating cam in which a base circle section and a lift section are continuous. Many of the same structures employ a rocker arm mechanism that changes the ratio of the base circle section and lift section replaced with a reciprocating cam, and the ratio is changed according to the driving state of the vehicle ( For example, see Patent Document 1).
Japanese Patent No. 3245492

  Engines are required to reduce pumping loss in order to reduce fuel consumption.

  By the way, considering the reduction of pumping loss, when changing the phase of the intake valve, it is desirable to make the valve opening timing almost the same and to change the phase (open / close timing) (intake air is sucked into the cylinder without loss) By creating a situation to be).

  However, the variable valve device disclosed in Patent Document 1 simply replaces the cam phase of the camshaft with a reciprocating cam, so that the obtained cam phase can be varied while the maximum lift amount is almost uniform. The timing and valve closing timing change.

  Therefore, in an engine equipped with such a reciprocating variable valve device, a variable valve device having a different system is used. Specifically, the cam itself is displaced in the advance or retard direction by hydraulic pressure. In combination with the variable valve system of the system, the phase of the intake valve is varied so that the valve opening timings are substantially aligned, thereby reducing the pumping loss.

  However, if the phase of the valve is varied with the help of such a variable valve system, it is necessary to correctly control both variable systems simultaneously in order to use a plurality of variable valve systems. In addition, there is a problem that since the phase variable amount needs to be increased, the responsiveness and the variable amount are insufficient, and there is a possibility that sufficient fuel consumption cannot be improved.

  In addition, the variable valve device disclosed in Patent Document 1 uses a structure in which each component of the variable valve device is assembled to each part of the cylinder header in turn. Since the load is applied, the adjustment of the operation variation between the cylinders is forced, and the adjustment work is difficult.

  Accordingly, an object of the present invention is to provide a variable valve operating apparatus for an internal combustion engine in which the valve closing timing can be made larger than the valve opening timing by a single rocker arm mechanism, and the variation in operation among cylinders can be easily adjusted. It is in.

  In order to achieve the above object, the rocker arm mechanism that is driven by a cam formed on the camshaft to open and close the intake or exhaust valve is supported by the rocker shaft so as to be swingable. A first arm that can be driven by a cam, a second arm that is driven by a cam and swings around the rocker shaft side as a fulcrum, and a support shaft that is disposed in the vicinity of the rocker shaft. In order to displace the contact position between the cam and the third arm that drives the first arm by changing the phase of the cam by the posture change caused by the movement of the fulcrum of the second arm in response to the displacement, forward and backward in the moving direction of the cam. In addition to a variable mechanism that displaces the fulcrum on the rocker shaft side of the two arms, the cam phase can be varied with the valve opening timing almost aligned, and the intake and exhaust rocker shafts Has a holding member for modularizing a rocker arm mechanism to hold the support shaft and, was configured to rocker arm mechanism in the holding member is fixed to the cylinder head.

  According to the second aspect of the present invention, in addition to the above object, the holding member includes an extending portion extending from one side of the intake or exhaust side rocker shaft to the side edge side of the cylinder head so that stable installation can be performed. By adopting a configuration having the above, the end portion of the extension portion and the other point away from the end portion are fixed to the cylinder head.

  According to a third aspect of the present invention, in addition to the above object, the rocker shaft supporting the first arm is rotationally displaced to displace the fulcrum of the second arm, and the rocker shaft can be easily and smoothly moved. The extending part of the holding member is fixed after the opposite end of the holding member is positioned on the cylinder head so that it can be assembled in a rotating state.

  According to a fourth aspect of the present invention, in addition to the above object, the third arm is configured so that the valve closing timing is changed more greatly than the valve opening timing so that the valve opening / closing timing and the valve lift amount can be varied continuously. Has a transmission surface portion in contact with the first arm to drive the first arm, and the transmission surface portion is provided with a conversion portion that changes the distance from the center of the support shaft, so that the displacement of the contact position is changed. As a result of the change in the posture of the second arm, the distance from the support shaft to the transmission surface is changed so that the phase of the cam transmitted to the first arm changes continuously with the valve lift amount of the intake or exhaust valve.

  According to the first aspect of the present invention, a simple single rocker arm mechanism that combines the first to third arms has a valve closing timing larger than the valve opening timing, which has an effect of reducing pumping loss. Variable.

  In addition, the rocker arm mechanism that changes the cam phase uses a structure in which the common intake and exhaust rocker shafts and the support shafts to which the parts of the rocker arm mechanism are assembled are held by a holding member and modularized. The adjustment of the operation timing between the cylinders can be easily performed with no load on the valve side before the cylinder head is assembled.

  According to the second aspect of the invention, in addition to the above effects, the holding member has a wide span and is fixed to the cylinder head, so that the variable valve apparatus can be installed with high stability.

  According to the third aspect of the present invention, in addition to the above effect, when the rocker shaft is pivotally displaced to displace the fulcrum of the second arm, the rocker shaft can be easily and smoothly rotated. Can be attached.

  According to the fourth aspect of the present invention, in addition to the above-described effect, the valve lift can be continuously varied with the valve closing timing varied more greatly than the valve opening timing.

[One Embodiment]
Hereinafter, the present invention will be described based on an embodiment shown in FIGS.

  FIG. 1 is a plan view of a cylinder head 1 of an internal combustion engine, for example, a reciprocating gasoline engine in which a plurality of cylinders (not shown) are arranged in series, and FIGS. 2 to 5 show different side sectional views of the cylinder head 1. . A combustion chamber 2 is formed on the lower surface of the cylinder head 1 along the longitudinal direction according to the arrangement of the cylinders as shown in FIG. For example, two (a pair) of intake ports 3 and exhaust ports 4 (only one side is shown) are provided for each combustion chamber 2. In addition, an intake valve 5 (configured by a reciprocating valve) for opening and closing the intake port 3 and an exhaust valve 6 (configured by a reciprocating valve) for opening and closing the exhaust port 4 are assembled to the upper portion of the cylinder head 1. Yes. Note that the plurality of intake valves 5 and the plurality of exhaust valves 6 are each of a normally closed type that is urged by a valve spring 7 in the closing direction. A valve system for driving a plurality of intake valves 5 and a plurality of exhaust valves 6, for example, a SOHC type valve system 8 is mounted on the upper portion of the cylinder head 1. FIG. 6 shows an exploded perspective view of the valve system 8.

  The valve system 8 will be described. In FIG. 1 to FIG. Reference numeral 11 denotes an upper side (one side in the cylinder head width direction) sandwiching the camshaft 10 and a pivotable intake-side rocker shaft disposed substantially parallel to the camshaft 10. Reference numeral 12 denotes the camshaft 10 on the opposite side. The exhaust-side rocker shaft 13 disposed substantially in parallel is a support shaft (corresponding to the support shaft of the present application) disposed substantially parallel to the camshaft 10, for example, at an upper point between the rocker shaft 11 and the rocker shaft 12. ). The camshaft 10 is a component that is rotationally driven along the arrow direction in FIG. 2 by the crank output of the engine. The camshaft 10 is formed with an intake cam 15 (one) and an exhaust cam 16 (two) for each combustion chamber 2. Specifically, the intake cam 15 is formed in a shaft portion which is a central point in the overhead of the combustion chamber 2, and the exhaust cam 16 is formed in both side portions sandwiching the intake cam 15 (FIG. 1). Only shown). Each part of this camshaft 10, for example, both axial ends, the shaft part between the cam groups between the cylinders, and the like are erected on the upper surface part corresponding to the above-mentioned parts of the cylinder head 1 as shown in FIGS. It is rotatably supported by a wall-like support base 17 extending in the cylinder head width direction. Reference numeral 17 a denotes a bearing portion formed at the center of the wall portion of the support base 17 that supports the camshaft 10.

  Among these, the rocker shaft 12 on the exhaust side has a pair of rocker arms 18 (only one side is shown) for each exhaust cam 16 (for each exhaust valve 6) and for each exhaust valve 6 as shown in FIGS. (Not shown) are rotatably provided. Each of these rocker arms 18 has a portion that is rotatably supported by the rocker shaft 12 as shown in FIGS. 1, 2, and 6, for example, a rocker shaft support boss 22. A roller member 23 serving as an abutment is rotatably provided at the end (one end) on the sandwiched camshaft 10 side, and the exhaust valve 6 is driven at the opposite end (the other end). A structure having a portion, for example, an adjusting screw portion 24 is used. 2 and 3, the roller member 23 of each rocker arm 18 is in rolling contact with the cam surface of the exhaust cam 16, and the opposite adjustment screw portion 27 protrudes from the upper portion of the cylinder head 1, respectively. It is arranged at the upper end (valve stem end) of the exhaust valve 6.

  Further, the rocker shaft 11 on the intake side is provided with a rocker arm mechanism 19 for driving a plurality (a pair) of intake valves 5 for each intake cam 15. When the intake cam 15 and the exhaust cam 16 are rotated by the rocker arm mechanism 19 and the pair of rocker arms 18, a predetermined combustion cycle (for example, four cycles of an intake stroke, a compression stroke, an explosion stroke, and an exhaust stroke). The intake valve 5 and the exhaust valve 6 are opened and closed at the timing at which

  The intake side rocker arm mechanism 19 employs a variable valve gear 20. The variable valve operating device 20 will be described. The rocker arm mechanism 19 constituting the device 20 has a rocker arm 25 (first) supported on the rocker shaft 11 so as to be swingable as shown in FIGS. 1 to 3 and FIG. 1), a center rocker arm 35 driven by the intake cam 15 (corresponding to the second arm), and a swing cam 45 (corresponding to the third arm) supported swingably on the support shaft 13. A combined structure is used.

  Of these, the rocker arm 25 employs a structure in which a portion for transmitting displacement to a plurality (a pair) of intake valves 5 as shown in FIG. For example, the rocker arm 25 has a cylindrical rocker shaft support boss 26 in the center, and a pair of rocker arms having a drive portion that drives the intake valve 5, for example, an adjustment screw portion 27, on one end side of the boss 26. A structure is used in which the pieces 29 are arranged in parallel, and a roller member 30 serving as an abutting member is rotatably sandwiched between the other end portions of the rocker arm pieces 29. Reference numeral 32 denotes a short shaft for pivotally supporting the roller member 30. 2, each rocker shaft support boss 26 of the assembled rocker arm 25 is inserted into the rocker shaft 11 so as to be swingable, and the roller member 30 is directed toward the center of the cylinder head 1 and remains. The adjusting screw part 27 is arranged at the upper end (valve stem end) of the intake valve 5 protruding from the upper part of the cylinder head 1.

  2, 3, and 6, the center rocker arm 35 has a rolling contact that makes rolling contact with the cam surface of the intake cam 15, for example, a cam follower 36, and a frame that rotatably supports the cam follower 36. A substantially L-shaped member having a holder portion 37 is used. Specifically, the center rocker arm 35 is centered on the cam follower 36, the relay arm portion 38 extending in a column shape upward from the holder portion 37, specifically, between the rocker shaft 11 and the support shaft 13, and the holder portion 37. And a fulcrum arm portion 39 having a flat plate shape extending downward from a side portion of the rocker shaft portion 11a (shown in FIGS. 8 to 11) exposed between the pair of rocker arm pieces 29, and having an L shape. Is formed. At the tip (upper end surface) of the relay arm portion 38, an inclined surface 40 is formed as a relay surface that transmits displacement to the swing cam 45, for example, so that the rocker shaft 11 side is low and the support shaft 13 side is high. It is. The remaining tip of the fulcrum arm 39 is supported by the rocker shaft portion 11a. For this support, for example, as shown in FIGS. 2, 6, and 8 to 11, a structure in which a pin member 41 combined with a fulcrum arm portion 39 is assembled to the rocker shaft portion 11 a in the diameter direction (radial direction). Is used. That is, the pin member 41 uses a component having a spherical portion 41a formed at the lower end and a threaded portion 41c formed on the outer peripheral surface. The pin member 41 advances and retreats toward the distal end portion of the fulcrum arm portion 39 so as to penetrate from the installation seat 11b (for example, formed of a notch portion) formed on the upper side of the rocker shaft portion 11a to the lower side (radial direction). It is fixed to the rocker shaft portion 11a by screwing possible and by tightening the end protruding from the mounting seat 11b with a lock nut 41b. Although not shown, the through hole through which the pin member 41 of the rocker shaft portion 41c passes is formed as a screw hole. The pin end protruding from the lower end of the rocker shaft portion 11 b is supported by the fulcrum arm 39. Specifically, a hemispherical receiving portion 42 is formed on the upper surface of the distal end portion of the fulcrum arm portion 39 so as to be fitted to the spherical portion 41a protruding from the rocker shaft portion 11a so as to be rotatable (movable). Thus, when the cam follower 36 is driven by the intake cam 15 by the same support, the center rocker arm 35 has the rocker shaft 11 side as a fulcrum, that is, with the pivot portion where the spherical portion 41a and the receiving portion 42 are fitted as a fulcrum. It swings up and down.

  Further, for example, a control motor 43 (shown only in FIG. 6) is connected to the end of the rocker shaft 11 as a control actuator. The pin member 41 shown in FIGS. 8 and 9 can be rotated and displaced in a range from a posture in which the pin member 41 is arranged in a substantially vertical direction to a posture inclined in the camshaft rotation direction shown in FIGS. 10 and 11. . That is, the fulcrum moving mechanism 44 (corresponding to the variable mechanism of the present application) constituted by the control motor 43 and the pivot support structure causes the fulcrum on the rocker shaft 11 side of the center rocker arm 35 to be in a direction intersecting the axial direction of the shaft 11. It can be moved (displaced). Using the positional shift of the center rocker arm 35 caused by this movement, the rolling contact position (contact position) of the cam follower 36 with respect to the intake cam 15 is variable as shown in FIGS. It can be displaced forward and backward in the direction of rotation.

  On the other hand, the swing cam 45 includes a cylindrical boss portion 46 that is rotatably inserted into the support shaft 13 as shown in FIGS. 2, 3, and 6, and the roller member 30 (the rocker arm 25 from the boss portion 46. ) And the displacement receiving portion 48 formed at the lower portion of the arm portion 47. Among these, a cam surface 49 extending in the vertical direction, for example, is formed at the tip of the arm portion 47 as a transmission surface portion that transmits displacement to the rocker arm 25. The cam surface 49 is in rolling contact with the outer peripheral surface of the roller member 30 of the rocker arm 25. For example, as shown in FIG. 6, in the displacement receiving portion 48, a recessed portion 51 is formed in a lower portion of the lower portion of the arm portion 47 that is directly above the camshaft 10, and the shaft 10 is placed in the recessed portion 51. , 11 and 12, and a structure in which the short shaft 52 is rotatably stored is used. More specifically, a concave portion 53 is formed in the lower portion of the short shaft 52 exposed from the opening portion of the concave portion 51, and the distal end portion of the relay arm portion 38 (center rocker arm 35) slides in the concave portion 53. It is inserted freely. A flat receiving surface 53 a that slidably receives the inclined surface 40 is formed on the bottom surface of the recess 53.

  That is, when the swing cam 45 receives the swinging displacement of the center rocker arm 35, the support shaft 13 serves as a fulcrum X, the recess 53 serves as an action point Y where a load from the center rocker arm 35 acts, and the cam surface 49 serves as the rocker arm 25. The driving force point Z is configured to periodically swing, and at the same time, the cam follower 36 is displaced from a predetermined position of the intake cam 15 in the advance angle direction or the retard angle direction (the center rocker arm 35 moves the intake cam 15). When the displacement of the swing arm 45 is caused by the displacement, the phase of the intake cam 15 is shifted in the advance direction (or the retard direction).

  The cam surface 49 is, for example, a curved surface (conversion unit of the present application) whose distance from the center of the support shaft 13 changes. For example, as shown in FIG. 2, the upper side of the cam surface 49 is formed by a base circle section α, that is, an arc surface centered on the axis of the support shaft 13 as shown in FIG. The lower part is formed by a lift section β, that is, an arc surface opposite to the arc and the arc surface opposite to the arc, for example, an arc surface similar to the cam shape of the lift area of the intake cam 15. A curved surface as an interval is used. When the cam follower 36 is displaced from the predetermined position of the intake cam 15 in the advance direction by the cam surface 49 (the fulcrum position of the center rocker arm 35 is displaced), the region of the cam surface 49 that the roller member 30 contacts changes. The ratio of the base circle section α and the lift section β where the member 30 passes is changed. Due to the change in the ratio of the sections α and β performed with the phase change in the advance direction, the opening / closing timing of the intake valve 5 is continuously varied while aligning the valve opening timing, and at the same time, the valve lift amount of the intake valve 5 Is continuously variable.

  Further, for example, a plus-shaped concave portion 55 (shown only in FIG. 6) is formed at the upper end portion of the pin member 41 as a receiving portion that receives a turning operation. The opening timing of the intake valve 5 can be adjusted for each cylinder by the concave portion 55 of the pin member 41, the screw insertion structure of the pin member 41 described above, and the nut 41b that locks the pin member 41 described above. (It is based on the screwing operation for displacing the pin member 41 in the forward direction and the backward direction with a driver tool, and the operation for unlocking and locking the nut 41b).

  1-3 and FIG. 6, 58 is a pusher for urging the arms of the rocker arm mechanism 19 in close contact, that is, for energizing the intake cam 15, the center rocker arm 35 and the swing cam 45 in close contact with each other. . The pusher 58 includes, for example, a vertical bottomed cylindrical holder portion 59 whose upper end portion is open as shown in FIGS. 2 and 3, and a lower end portion that is vertically inserted into the opening portion of the holder member 59. A bottomed cylindrical movable part 60 with a spring open, and a spring member, for example, a coil spring 61, housed between the inner bottom surface of the holder part 59 and the inner bottom surface of the movable part 60 in the holder part 59. Configured. The pusher 58 is disposed on the cylinder block 1 so as to urge the swing cam 45 upward from below. That is, the pusher 58 is formed on, for example, a rib-shaped receiving portion 67 formed so as to protrude from the outer peripheral surface of the boss portion 46 toward the side opposite to the arm portion 47 and an upper surface portion of the cylinder head 1 below the rib-shaped receiving portion 67. It is interposed between the pedestal 68. Specifically, the pusher 58 forms, for example, a mounting leg 63 extending to a lower side of the holder part 59, for example, at a part of the holder part 61 as shown in FIGS. In addition, a structure in which a C-shaped fitting portion 64 that can be fitted to the exhaust-side rocker shaft 12 is formed for the fulcrum, and a receiving seat 65 is formed in the lower stage of the installation leg 63 to receive the reaction force is used. ing. The receiving seat 65 is formed, for example, by bending the tip end portion of the installation leg 63 in a direction aligned with the lower side of the holder portion 59. Then, the pusher 58 abuts against the lower surface of the receiving portion 67 formed on the front end surface of the movable portion 60 and fits into the portion of the rocker shaft 12 directly below the receiving portion 67. In the posture in which the receiving seat 65 is placed on the lower base portion 68 of the rocker shaft 12 portion, it is interposed between the receiving portion 67 and the upper surface of the cylinder head 1. Of course, when the pusher 58 is mounted between the receiving portion 67 and the base portion 68, the movable portion 60 is pushed. And, by the compression deformation of the coil spring 61 brought about by the pushing of the movable part 60, the swing cam 45 is urged from the direction from the lower side to the upper side from the fulcrum X side so that the arms are not always separated from each other. It is in close contact (to suppress lost motion).

  The rocker arm on the intake side such as the rocker shaft 11 (intake side), rocker shaft 12 (exhaust side) and support shaft 13 of the valve train 8 such as the shaft portions between the cam groups between both ends in the axial direction. A portion adjacent to the mechanism 19 and the pair of rocker arms 18 on the exhaust side, a portion between the rocker arm mechanism 19 on the intake side and the pair of rocker arms 18 on the exhaust side, etc., as shown in FIG. It is held by holding members 70a and 70b of a kind.

  This holding structure will be described. The holding member 70a is a component suitable for holding a point where a space for fixing near the rocker shaft 11 is secured on the upper surface of the cylinder head, for example, a shaft end. The remaining holding member 70b is a part suitable for holding the shaft portion between the cylinders (between the cam groups), for example, at a point where a space for fixing cannot be secured near the rocker shaft 11.

  Among these members, the holding member 70a has a main body 72 that can be placed on the support base 17 disposed at the front-rear direction end of the cylinder head 1 as shown in FIG. On the side portion of the main body portion 72, fitting insertion portions 73 and 74 that are fitted to the ends of the rocker shafts 11 and 12 are formed. Of the fitting insertion portions 73 and 74, for example, the one-side fitting insertion portion 73 into which the end of the rocker shaft 12 on the exhaust side is fitted is formed in a cylindrical shape, and the insertion on one side into which the end of the rocker shaft 11 on the intake side is fitted. The portion 74 is formed in a bottomed cylindrical shape that rotatably houses the end of the rocker shaft 11. Further, a columnar receiving portion 75 that supports the end of the support shaft 13 from the lower side protrudes from the upper portion of the main body portion 72, for example, between the fitting insertion portions 73 and 74. The end of the support shaft 13 is fixed to the receiving portion 75 by a fastener, for example, a bolt member 76, which penetrates the support shaft 13 from above and is screwed into the receiving portion 75. With such a fixing structure and an insertion structure, the ends of the support shaft 13 and the rocker shafts 11 and 12 are held by the holding member 70a while maintaining a predetermined interval.

  Further, the holding member 70a is arranged on one side in consideration that the part where the holding member 70a is disposed is the front-rear direction end of the cylinder head 1 (part where a fixed space is easily secured on both the exhaust side and the intake side). In the fixing structure, for example, as shown in FIGS. 5 and 6, a fixing seat surface 77 a is formed on the upper surface portion of the fitting insertion portion 73, and the lower surface portion of the fitting insertion portion 73 is flush with the lower surface of the main body portion 72. A structure is used in which a surface 77b is formed and a passage 77c is formed from the fixing seat surface 77a through the rocker shaft 12 to the installation surface 77b. Further, in the structure for fixing the remaining one side, for example, as shown in FIG. 5 and FIG. 6, a boss portion 79 projecting outward in the axial direction is formed at a portion forming the bottom portion of the fitting insertion portion 74. A fixing seat surface 79 a is formed on the upper surface of the boss portion 79, an installation surface 79 b flush with the lower surface of the main body 72 is formed on the lower surface of the boss portion 79, and the space between the fixing seat surface 79 a and the installation surface 79 b is formed in the boss portion 79. A structure in which a communication path 79c is formed is used.

  As shown in FIG. 6, the holding member 70 b includes a cylindrical fitting insertion portion 81 that is slidably fitted to the intake-side rocker shaft 11 and a cylindrical fitting insertion portion 82 that is fitted to the exhaust-side rocker shaft 12. And a main body 84 formed by integrally connecting a wall-shaped receiving portion 83 that supports the support shaft 13 from below. As shown in FIG. 1, each part of the main body part 84 (insertion parts 81, 82, receiving part 83) is a part between cylinders, that is, a rocker shaft 11 part between rocker arm mechanisms 19, and a pair of rocker arms 18. The support shaft 13 is interposed between the rocker shaft 12 and the boss 46 of the swing cam 45. And the support shaft 13 part on the receiving part 83 is fixed to the receiving part 83 with the fastener which penetrates the support shaft 13 from the upper side, and is screwed in to the receiving part 83, for example, the bolt member 86, Each shaft 11-13 The intermediate portion is held by the holding member 70b while maintaining a predetermined interval.

  By holding the intermediate portions of the shafts 11 to 13 by the holding member 70b and holding the ends of the shafts 11 to 13 by the holding member 70a described above, the rocker arm mechanism 19 (variable valve gear 20 as shown in FIG. 7). Of course, the parts of the valve operating system 8 mounted on the cylinder head 1 including the rocker arm mechanism 19 are modularized into one structure X.

  In addition, the holding member 70b takes into account that the portion where the holding member 70b is disposed is in the middle in the front-rear direction of the cylinder head 1 (for example, either the intake side or the exhaust side is fixed due to the influence of the cylinder, the water jacket, etc.) In consideration of the cylinder head structure in which it is difficult to secure a fixed space near the intake-side rocker shaft 11, the exhaust-side fixed structure includes, for example, FIG. As shown in FIG. 6, a fixing seat surface 87a is formed on the upper surface portion of the fitting insertion portion 81, an installation surface 87b is formed below the fitting insertion portions 81 and 82, and the rocker shaft 12 is further extended from the fixing seat surface 87a. The structure which formed the channel | path 87c which reaches to the installation surface 87b through is used. For example, as shown in FIGS. 4 and 6, the remaining intake side fixing structure is separated from the side edge side (one side in the width direction) of the cylinder head 1 avoiding the periphery of the rocker shaft 12 that cannot be fixed, for example, away from the rocker shaft 12. A structure is used in which the seating surface 1a formed near the side edge of the cylinder head 1 can be fixed. Specifically, in the fixing structure, an extension portion 88 extending toward the seating surface 1 a is formed on the side portion of the fitting insertion portion 81 that is one side of the main body portion 84, and an end portion of the extension portion 88 is formed. A structure in which a fixing through-hole 89 is formed along the vertical direction is used.

  Using such a fixing structure, the structure X is fixed to the upper surface of the cylinder head 1 as shown in FIG. That is, in the structure X, as shown in FIGS. 4 and 5, each holding member 70 a is placed on the set surface 17 b formed on the upper surface of the support base 17 disposed on both sides in the front-rear direction of the cylinder head 1. After each holding member 70b is placed on the set surface 17b or the seating surface 1a formed on the upper surface of the support base 17 disposed in the middle in the front-rear direction of the cylinder head 1, the seating surface 77a of each holding member 70a is placed. 79a, the bolt member 90 is screwed into the set surface 17b of the support base 17, the bolt member 90 is screwed from the fixing seat surface 87a of each holding member 70b to the set surface 17b of the support base 17, and a through hole 89 is further inserted. The bolt member 90 is screwed into the seat surface 1a so as to be fixed to the upper surface of the cylinder head 1 while avoiding the right side of the intake side rocker shaft 11.

  Further, as shown in FIG. 1, initial positioning when the structure X is mounted on the cylinder head 1 is performed on the lower portion of the fitting insertion portion 82 of each holding member 70 b and the upper surface portion of the support base 17 corresponding thereto. A positioning knock pin portion 92 is formed. When the ends of the extending portions 88 of the holding members 70a and 70b are fixed, the holding members 70a and 70b are fixed after being positioned by the knock pin portion 92 at a point away from the extending portion 88.

  2 denotes a spark plug (a device for igniting the air-fuel mixture in the combustion chamber 2) attached to the cylinder head 1 between the rocker arm pieces 29 and 29 on the intake side.

  Next, the operation of the variable valve operating apparatus 20 configured as described above will be described.

  First, the movement of the rocker arm mechanism 19 accompanying opening and closing of the intake valve 5 will be described. It is assumed that the camshaft 10 is rotating (in the direction of the arrow) as shown in FIG.

  At this time, as shown in FIG. 2, the cam follower 36 of the center rocker arm 35 receives the intake cam 15 disposed between the rocker arm pieces 29 and is driven according to the cam profile of the cam 15. Then, the center rocker arm 35 is swung in the vertical direction with the pivot portion on the rocker shaft 11 side as a fulcrum. This swinging displacement is transmitted to the swing cam 45 directly above the center rocker arm 35.

  Here, one end portion of the swing cam 45 is swingably supported by the support shaft 13, and the other end portion is in rolling contact with the roller member 30 of the rocker arm 25. From this state, the inclined surface 40 at the tip of the relay arm portion 38 is received by the receiving surface 53a formed on the rotatable short shaft 52 at the bottom. As a result, the swing cam 45 repeats the behavior of being pushed up or lowered by the inclined surface 40 while sliding on the inclined surface 40. By swinging the swing cam 45, the cam surface 49 is driven in the vertical direction.

  At this time, since the roller member 30 is in rolling contact with the cam surface 49, the roller member 30 is periodically pressed by the cam surface 49. In response to this pressing, the rocker arm 25 is driven (swinged) with the rocker shaft 11 as a fulcrum, and opens and closes a plurality (a pair) of intake valves 5 at a time.

  During such operation, the operation of the control motor 43 causes the rocker shaft 11 to rotate, for example, to move the fulcrum position of the center rocker arm 35 to a point where the maximum valve lift amount is secured. Then, from the displacement of the fulcrum position, the cam follower 36 of the center rocker arm 35 is displaced on the intake cam 15 as shown in FIG. 2, and the cam surface 49 of the swing cam 45 is at an angle close to vertical (base circle section α). Position it to the posture that

  As a result, the cam surface 49 has a region (ratio) where the roller members 30 come and go to provide the maximum valve lift amount, that is, the shortest base circle section α shown in FIG. 8 and the longest lift section shown in FIG. 9. set to β. Then, the intake valve 5 follows the rocker arm 25 driven by the cam surface portion formed by the narrow base circle section α and the longest lift section β, and the maximum valve lift amount as shown in the diagram of A1 in FIG. Furthermore, it is opened / closed at a desired opening / closing timing.

  From this state, when the phase of the intake cam 15 is varied, the operation of the control motor 43 causes the rocker shaft 11 to move from a position where the maximum valve lift amount is secured (position of the pin member 41 in FIGS. 8 and 9). Rotate clockwise. Thereby, the pivot part (fulcrum position) of the center rocker arm 35 is shifted to the camshaft 10 side.

  Here, the center rocker arm 35 is formed by the inclined surface 40 of the relay arm portion 38 and the receiving surface 53a of the short shaft 52 that is in surface contact with the inclined surface 40, and transmits the displacement to the swing arm 45. Since the portion that receives the cam 15 is formed by the cam follower 36 that is in rolling contact with the intake cam 15, when the displacement (displacement) is received, the center rocker arm 35 as a whole has the rolling contact position of the cam follower 36 of the intake cam 15. Displace (shift) to advance in the advance direction. Due to the change in the rolling position, the valve opening timing of the cam phase to be varied is advanced according to the variable amount of the pivot portion (fulcrum position).

  The inclined surface 40 is also displaced (slid) in the advance direction on the receiving surface 53a from the initial position in response to the movement of the fulcrum. As a result, the swing cam 45 changes to a posture in which the cam surface 49 is inclined downward as shown in FIGS. As this inclination increases, the region of the cam surface 49 where the roller members 30 come and go changes to a region where the base circle section α is gradually longer and the lift section β is gradually shorter. Then, the cam profile of the variable cam surface 49 is transmitted to the roller member 30, and the rocker arm 25 is driven to swing while the valve opening timing is advanced. Thereby, the opening / closing timing of the intake valve 5 is the minimum valve lift amount obtained by tilting the pin member 41 from the maximum valve lift amount A1 as shown in FIG. 9 according to the movement of the fulcrum position of the center rocker arm 35. Until A7, variable control is continuously performed while maintaining the valve opening timing from substantially the same valve opening timing as at the time of maximum valve lift. 10 and 11 show the state when the minimum valve lift amount A7 is set in the variable control.

  Therefore, the valve closing timing can be made larger than the valve opening timing only by a single rocker arm mechanism 19 in which the rocker arm 25, the center rocker arm 35 and the swing cam 45 are combined. Can do. In addition, the swing cam 45 has a structure in which the distance from the support shaft 13 to the cam surface 49 is changed so that the cam phase transmitted to the rocker arm 25 is continuously varied along with the valve lift amount. The opening / closing timing of the intake valve 5 and the valve lift amount can be varied simultaneously at substantially the same timing. Continuously changing the valve lift amount and opening / closing timing at almost the same timing for opening the valve allows intake air to be sucked into the cylinder while suppressing loss, and is particularly effective in reducing pumping loss. Demonstrate.

  In addition, each part of the rocker arm mechanism 19 uses the holding members 70a and 70b to hold the intake-side rocker shaft 11, the exhaust-side rocker shaft 12, and the support shaft 13 that are common parts and modularize them. Since the structure is fixed to the head 1, when adjusting the operation timing between the cylinders, there is no load from the intake / exhaust valves 5 and 6 before the cylinder head 1 is assembled as shown in FIG. Since the body X can be used as it is, adjustment is easy. Furthermore, since the holding member 70b is structured to be fixed to the cylinder head 1 with a wide span by forming the extending portion 88, the structure X can be incorporated into the cylinder head 1 with high stability.

  In particular, when the rocker shaft 11 is rotationally displaced to displace the fulcrum of the center rocker arm 35, the holding member 70 b that holds the exhaust side rocker shaft 12 and the intake side rocker shaft 11 is relative to the intake side rocker shaft 11. Since the end portion of the extending portion 88 extending to the opposite side of the exhaust side rocker shaft 12 is fixed to the cylinder head 1, the knock pin 90 that fixes the end portion of the extending portion 88 to the cylinder head 1 is the center. The displacement of the holding member 70b is smaller in the fitting insertion portion 81 that holds the intake-side rocker shaft 11 than in the fitting insertion portion 82 that holds the exhaust-side rocker shaft 12, and the displacement of the fitting insertion portion 81 is kept small. Therefore, the clearance necessary for the smooth movement of the rocker shaft 11 can be easily secured between the rocker shaft 11 and the holding member 70b. .

  Further, by providing the push knock 92 to the mounting portion of the knock pin 90 that fixes the extending portion 88 of the holding member 70b to the cylinder head 1, the displacement of the holding member 70b itself is suppressed, so that the displacement of the intake side rocker shaft 11 is reduced. It is further suppressed.

  Even if the phase varying device is used in combination with the present invention, the amount of phase variation can be small, so that a variable response delay does not occur, and sufficient fuel consumption can be improved.

  The present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the structure in which the end portion on the intake side of the holding member is extended has been described. However, the structure is not limited to this, and the end portion on the exhaust side may be extended depending on the cylinder head structure. Good.

The top view which shows the variable valve apparatus of one Embodiment of this invention with the cylinder head which mounts the apparatus. Sectional drawing which follows the AA line in FIG. Sectional drawing which follows the BB line in FIG. Sectional drawing which follows the CC line | wire in FIG. Sectional drawing which follows the DD line | wire in FIG. The disassembled perspective view of the valve operating system of the intake / exhaust valve including the variable valve operating apparatus. The disassembled perspective view which shows the variable valve operating apparatus modularized. Sectional drawing which shows a state when the contact part of a rocker arm exists in the base circle area of the cam surface at the time of the maximum valve lift control of the variable valve apparatus. Sectional drawing which shows a state when the contact part of a rocker arm exists in the lift area of a cam surface similarly. Sectional drawing which shows a state when the contact part of a rocker arm exists in the lift area of the cam surface at the time of the minimum valve lift control of the variable valve apparatus. Sectional drawing which shows a state when the contact part of a rocker arm exists in the lift area of a cam surface similarly. The diagram which shows the performance of the variable valve operating apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 5 ... Intake valve, 6 ... Exhaust valve, 10 ... Cam shaft, 11 ... Intake side rocker shaft, 12 ... Exhaust side rocker shaft, 13 ... Support shaft (support shaft), 19 ... Rocker arm mechanism, 20 ... Variable valve Device: 25 ... Rocker arm (first arm), 35 ... Center rocker arm (second arm), 44 ... Supporting point moving mechanism (variable mechanism), 45 ... Swing cam (third arm), 49 ... Cam surface (transmission surface), 70a, 70b ... holding member, 88 ... extension part, 92 ... bush knock, X ... modularized structure, [alpha], [beta] ... base circle section, lift section (conversion part).

Claims (4)

A camshaft rotatably provided on a cylinder head of an internal combustion engine;
An intake and exhaust rocker shaft arranged in parallel with the camshaft;
A variable valve operating apparatus for an internal combustion engine having a rocker arm mechanism that is driven by a cam formed on the camshaft to open and close an intake or exhaust valve;
The rocker arm mechanism is
A first arm supported swingably on the rocker shaft and capable of driving an intake or exhaust valve;
A second arm that abuts on the cam and is driven by the cam and swings about the rocker shaft side;
The cam is provided on a support shaft disposed in the vicinity of the rocker shaft so as to be swingable. The displacement of the second arm causes a change in the posture of the second arm caused by movement of the fulcrum of the second arm. A third arm that drives the first arm with a variable phase;
A variable mechanism for displacing the fulcrum of the second arm on the rocker shaft side so as to displace the abutting position with the cam in the longitudinal direction of the cam;
A holding member that holds the intake and exhaust rocker shafts and the support shaft and modularizes the rocker arm mechanism;
The variable valve operating apparatus for an internal combustion engine, wherein the rocker arm mechanism is fixed to the cylinder head via the holding member. The holding member has an extending portion extending from one side of the intake or exhaust side rocker shaft to the side edge side of the cylinder head, and an end portion of the extending portion and the other side separated from the end portion The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein a point on the side is fixed to the cylinder head. The variable mechanism is configured to displace a fulcrum of the second arm on the rocker shaft side when the rocker shaft supporting the first arm is rotationally displaced.
The holding member has an extending portion extending from a rocker shaft side supporting the first arm to a side edge side of the cylinder head, and an end portion of the extending portion and the holding member separated from the end portion. The opposite end is fixed to the cylinder head,
The variable valve operating apparatus for an internal combustion engine according to claim 2, wherein the extending portion of the holding member is fixed after the opposite side of the holding member is positioned on the cylinder head. The third arm has a transmission surface portion in contact with the first arm to drive the first arm,
The transmission surface portion includes a conversion portion whose distance from the center of the support shaft changes,
The phase of the cam transmitted to the first arm is changed together with the valve lift amount of the valve by changing the distance from the support shaft to the transmission surface portion from the change in posture of the second arm caused by the displacement of the contact position. The variable valve operating device for an internal combustion engine according to any one of claims 1 to 3, wherein the variable valve device is continuously variable.

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