JP2011190757A - Variable valve device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the need for a particularly high hydraulic pressure in changing valve action characteristics and also the need for valves and the like which control the high hydraulic pressure in a variable valve device of an internal combustion engine in which at least one of a plurality of rocker arms which is disposed so as to be respectively abutted to and adjacent to a plurality of cams is connected to and operates with an engine valve, and the connection and disconnection of each rocker arm are switched to each other by a valve action characteristics changing means. <P>SOLUTION: The valve action characteristics changing means 60 is provided with a plurality of connection pins 63, 64, 65 and 66 which are abutted to each other and fitted in respective rocker arms 32, 33, 34 and 35, and shift arms 67, 68 and 69 which are respectively abutted to and engaged with the axial outer ends of the connection pins 63, 64, 65 and 66 at the both ends in the array direction to form pairs, and thereby can interlockingly be moved, wherein the connection pins 63, 64, 65 and 66 at the both ends in the array direction alternatively project from the rocker arms 32, 33, 34 and 35 responding to the connection and disconnection of the rocker arms 32, 33, 34 and 35. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides a camshaft in which a plurality of cams having different cam profiles are provided, and a camshaft that is capable of swinging around an axis parallel to the camshaft while abutting the cams individually. The operation characteristics of the engine valve are changed by switching the connection and release of a plurality of rocker arms that are adjacent to each other in the direction parallel to the axis of the engine and that are linked and connected to at least one of the engine valves and the rocker arms adjacent to each other. The present invention relates to a variable valve operating apparatus for an internal combustion engine comprising a changeable valve operating characteristic changing means.

  Axial movement of connecting pins that are slidably fitted to the rocker arms and connected to and disengaged from a plurality of rocker arms that are arranged adjacent to each other so as to individually follow cams of different cam profiles. Patent Document 1 discloses a variable valve operating apparatus for an internal combustion engine that changes the operating characteristics of an engine valve that is linked to and connected to at least one of the rocker arms.

JP 2002-303109 A

  The valve operating characteristic changing means of the variable valve operating device disclosed in Patent Document 1 includes a plurality of connecting pins that come into contact with each other and are slidably fitted to a rocker arm. By connecting the rocker arms, the connection and release of the rocker arms are switched by moving the connecting pins in the axial direction by controlling the oil pressure. However, such a valve operating characteristic changing means requires a high oil pressure different from the oil pressure required for lubricating the internal combustion engine and valves for controlling the oil pressure, so that originally no high oil pressure is required. In an internal combustion engine, for example, an internal combustion engine having a rolling bearing type crankshaft or a small internal combustion engine, a dedicated hydraulic power source or a hydraulic pressure from the hydraulic power source is controlled in order to constitute a valve operating characteristic changing means. Equipped with a control valve or the like that was difficult to achieve due to cost and space constraints.

  The present invention has been made in view of such circumstances, and does not require a particularly high hydraulic pressure when changing valve operating characteristics, and does not require valves or the like for controlling the high hydraulic pressure. The purpose is to provide.

  In order to achieve the above object, the present invention provides a camshaft provided with a plurality of cams having different cam profiles, and swings around an axis parallel to the camshaft by individually contacting the cams. A plurality of rocker arms which are arranged adjacent to each other in a direction parallel to the axis of the camshaft and at least one of which is linked and connected to the engine valve, and connection and release of the rocker arms adjacent to each other are switched. In the variable valve operating apparatus for an internal combustion engine, the valve operating characteristic changing unit is configured to switch connection and disconnection of a plurality of rocker arms. A plurality of connecting pins that are brought into contact with each other and fitted to each rocker arm while allowing the rocker arms to slide in the arrangement direction And a shift arm that makes a pair so as to abut and engage with the outer ends in the axial direction of the connecting pins at both ends in the arrangement direction of the connecting pins and is movable in conjunction with the arrangement direction of the rocker arms. The connection pins at both ends in the arrangement direction among the connection pins that are in contact with each other are selected according to the connection and release of the plurality of rocker arms from the rocker arm to which the connection pins at the both ends are fitted. The first feature is that the axial length of each of the connecting pins is set so as to protrude in the direction.

  According to the present invention, in addition to the configuration of the first feature, each of the rocker arms has a cylindrical support shaft that rotatably supports a roller that is in rolling contact with a plurality of cams provided on the camshaft. The second feature is that the connecting pins are slidably fitted into the support shafts.

  According to the present invention, in addition to the configuration of the first feature, the plurality of rocker arms have an axis parallel to the camshaft and are slidable on a rocker shaft supported on the engine body so as to be able to slide in the axial direction. A third feature is that the shift arm is movably supported and is linked and coupled to the rocker shaft so as to operate together with the rocker shaft.

  According to the present invention, in addition to the configuration of the first feature, a lost motion is provided in a power transmission path of a shift drive unit that is linked and coupled to the shift arm so as to move the shift arm in the arrangement direction of the rocker arms. A fourth feature is that a mechanism is interposed.

  According to the present invention, in addition to the configuration of the fourth feature, one of the pair of shift arms can be moved in the arrangement direction of the rocker arms and fixed to a moving body connected to the shift driving means. When the moving body moves between the other shift arm and the one shift arm or the engine body, the other shift arm moves to the side where the pressing force is applied to the connecting pin. A fifth feature is that a lost motion spring is provided for allowing the other shift arm to follow the movement of the arm.

  In order to achieve the above object, the present invention provides a plurality of intake side cams and exhaust side cams each having a different cam profile, and a single camshaft that is disposed in common for the intake and exhaust valves. , Each of the plurality of intake-side cams individually contacting and swinging around an axis parallel to the camshaft while being arranged adjacent to each other in a direction parallel to the camshaft axis and at least one of the intake-side cams A plurality of intake-side rocker arms that are linked to and connected to the valve and a plurality of the exhaust-side cams individually abutting and swinging around an axis parallel to the camshaft while being parallel to the axis of the camshaft A plurality of exhaust-side rocker arms that are arranged adjacent to each other and that are linked and connected to an exhaust valve, and the intake-side and In a variable valve operating apparatus for an internal combustion engine, comprising: a valve operating characteristic changing unit capable of changing an operating characteristic of the intake valve and the exhaust valve by switching connection and release of an air side rocker arm; The plurality of intake-side rocker arms can be slid in the arrangement direction of the intake-side rocker arms by switching the connection and release of the intake-side rocker arms, and a plurality of the intake-side rocker arms are brought into contact with each other and fitted to the intake-side rocker arms. The exhaust side rocker arm and the exhaust side rocker arm can be slid in the arrangement direction of the exhaust side rocker arms so as to switch the connection and release of the plurality of exhaust side rocker arms. A plurality of exhaust side connection pins to be fitted and a first end that contacts and engages an outer end of the intake side connection pin at one end in the arrangement direction of the plurality of intake side connection pins. The shift arm contacts and engages with the outer end of the intake side connection pin at the other end of the plurality of intake side connection pins in the arrangement direction, and is outside the exhaust side connection pin at one end of the plurality of exhaust side connection pins in the arrangement direction. A second shift arm that contacts and engages with the end; and a third shift arm that contacts and engages with the outer end of the exhaust side connection pin at the other end in the arrangement direction of the plurality of exhaust side connection pins. Of the intake side and exhaust side connection pins that are in contact with each other, the intake side and exhaust side connection pins at both ends in the arrangement direction are fitted with the intake side and exhaust side connection pins at both ends thereof. The axial lengths of the respective connecting pins are set so as to selectively protrude from the intake side and exhaust side rocker arms that are connected to and disconnected from the intake side and exhaust side rocker arms. 1st to 3rd shift door A sixth feature is that the engine is interlocked and connected so as to move in association with the arrangement direction of the intake side and exhaust side rocker arms.

  According to the present invention, in addition to the configuration of the sixth feature, shift drive means having a lost motion mechanism interposed in the power transmission path moves the second shift arm in the arrangement direction of the intake side and exhaust side rocker arms. In this way, the first and third shift arms are connected to the second shift arm, and the first and third shift arms are moved between the first and third shift arms and the second shift arm or the engine body. A seventh feature is that a lost motion spring for following the arm is provided.

  In addition to the configuration of the sixth or seventh feature, the present invention connects the intake side rocker arms and the exhaust side rocker arms, and the operating positions for releasing the connection between the intake side rocker arms and the exhaust side rocker arms. An eighth feature is that a shift holding mechanism that elastically holds the operating position of the second shift arm movable between the operating positions is provided.

  According to the present invention, in addition to the configuration of the fourth feature, the shift driving unit is configured to rotate the rotation member supported rotatably on the engine body so that the shift arm includes the shift arm along the arrangement direction of the rocker arms. It has a ninth feature that it has a cam mechanism that is converted into movement.

  According to the present invention, in addition to the ninth feature, the rotating member is an input pulley around which a drive cable is wound, and the lost member is interposed between the input pulley and the input member of the cam mechanism. A tenth feature is that a motion mechanism is provided.

  In addition to the ninth feature, the eleventh feature is that the drive mechanism of the throttle valve is connected to the rotating member so that the cam mechanism is switched at a predetermined throttle opening. And

  According to the present invention, in addition to the configuration of the first or sixth feature, a governor mechanism connected to the camshaft so as to generate axial thrust by rotation of the camshaft is linked to and connected to the shift arm. This is a twelfth feature.

  According to the present invention, in addition to the configuration of the first or sixth feature, the cam shaft is interposed between the combustion chamber and a cam holder provided in a cylinder head so as to rotatably support the cam shaft. In this way, the support plate is fixed, a pair of electromagnetic actuators are disposed on the support plate, and the link is interlocked and connected to the shift arm to be able to rotate between the first and second operating positions. A thirteenth feature is that both the electromagnetic actuators are connected so as to rotate the link.

  Further, according to the fourteenth aspect of the present invention, in addition to the thirteenth feature, a shift holding spring for holding the first and second operating positions of the link is provided between the link and the support plate. It is characterized by.

  The intake valve 25 and the exhaust valve 26 of the embodiment correspond to the engine valve of the present invention, and the intake side and exhaust side rocker shafts 42 and 43 of the embodiment correspond to the moving body of the present invention. The input pulley 71 corresponds to the rotating member of the present invention, and the third intake side lost motion springs 93 and 104 and the third exhaust side lost motion springs 94 and 105 of the embodiment correspond to the lost motion spring of the present invention.

  According to the first feature of the present invention, a plurality of connecting pins that are brought into contact with each other so as to switch connection and disconnection of a plurality of rocker arms are fitted to each rocker arm, and are arranged at both ends of the connecting pins in the arrangement direction. A pair of shift arms that make contact with and engage with the outer ends of the connecting pins in the axial direction move in conjunction with the arrangement direction of the rocker arms to drive the connecting pins in the axial direction. Therefore, high hydraulic pressure is not required to drive the connecting pin, and valves that control the high hydraulic pressure are not required, increasing the cost of internal combustion engines with rolling bearing crankshafts and small internal combustion engines. The valve operating characteristic changing means can be easily applied while avoiding the problem of securing the space and avoiding the problem.

  Further, according to the second feature of the present invention, the connecting pin is slidably fitted in a cylindrical support shaft fixed to each rocker arm so as to rotatably support the roller that is in rolling contact with the cam. Therefore, it is unnecessary to secure a dedicated space for arranging the connecting pins in the rocker arm, which can contribute to downsizing of the rocker arm.

  According to the third feature of the present invention, the rocker shaft for pivotably supporting the plurality of rocker arms is supported on the engine body so as to be slidable in the axial direction, and the shift arm is linked and coupled to the rocker shaft. Therefore, the structure for driving the shift arm is simplified, and the number of parts can be reduced.

  According to the fourth aspect of the present invention, since the shift driving means including the lost motion mechanism is linked and connected to the shift arm, the shift arm is moved until the connection pin can be moved during the closing period of the engine valve. The connection pin can be moved quickly when the engine valve is in the valve closing period.

  According to the fifth feature of the present invention, one of the pair of shift arms is fixed to a moving body connected to the shift driving means, and between the other shift arm and one shift arm or the engine body. A lost motion spring is provided to follow the other shift arm when one shift arm moves to the side where the pressing force is applied to the connecting pin from the other shift arm, so that the connecting pin is pressed by the other shift arm. When the connecting pin is moved, the shift arm is allowed to wait until the connecting pin can be moved during the closing period of the engine valve. Can be moved to.

  According to the sixth aspect of the present invention, a plurality of intake side connection pins that are brought into contact with each other so as to switch connection and release of a plurality of intake side rocker arms are fitted to each intake side rocker arm, A plurality of exhaust-side connection pins that are brought into contact with each other so as to switch the connection and release of the exhaust-side rocker arm are fitted to each exhaust-side rocker arm, and are arranged outside the intake-side connection pin at one end in the arrangement direction of the intake-side connection pins The first shift arm is brought into contact with and engaged with the end, and the outer end of the intake side connection pin at the other end in the arrangement direction of the intake side connection pin and the outer end of the exhaust side connection pin at one end in the arrangement direction of the exhaust side connection pin The second shift arm is brought into contact with and engaged, and the third shift arm is brought into contact with and engaged with the outer end of the exhaust side connection pin at the other end in the arrangement direction of the exhaust side connection pins. Move in conjunction with the third shift arm In order to drive the intake side and exhaust side connection pins, high hydraulic pressure is not required, and valves for controlling the high hydraulic pressure are not required, and a rolling bearing type crankshaft is provided. The valve operating characteristic changing mechanism can be easily applied to an internal combustion engine or a small internal combustion engine while avoiding an increase in cost. In addition, when changing the valve operating characteristics of the intake valve and the exhaust valve, the second shift arm can be made common on the intake valve side and the exhaust valve side, thereby reducing the number of parts and simplifying the structure.

  According to the seventh feature of the present invention, since the shift driving means having the lost motion mechanism interposed in the power transmission path is connected to the second shift arm, the second shift arm is connected to the intake side or exhaust side connection pin. When moving so as to press the engine, the shift of the shift arm is made to wait until the intake side or exhaust side connecting pin can be moved during the closing period of the engine valve, and the engine valve becomes the closing period. In this case, the intake side or exhaust side connection pin can be quickly moved. Lost motion springs that cause the first and third shift arms to follow the movement of the second shift arm are provided between the first and third shift arms and the second shift arm or the engine body, respectively. Therefore, when pressing the intake side connection pin with the first shift arm to move the intake side connection pin, and when pressing the exhaust side connection pin with the third shift arm to move the exhaust side connection pin, The movement of the first and third shift arms is made to wait until the intake side and the exhaust side connection pin can be moved during the closing period of the intake valve and the exhaust valve. When this happens, the intake side and the exhaust connection pin can be moved quickly.

  According to the eighth aspect of the present invention, the second shift arm connects the intake position rocker arm and the exhaust side rocker arm to each other and the connection position of the intake side rocker arm and the exhaust side rocker arm. It moves between the operating positions, and the operating position is held elastically by the shift holding mechanism, so that the certainty of the operation can be ensured.

  According to the ninth aspect of the present invention, the shift driving means is configured to convert the rotation operation of the rotation member into the movement of the shift arm by the cam mechanism. The driving force input to the member can be easily converted into the linear movement of the shift arm, so that the shift driving means can be made compact and the reliability of the operation can be ensured.

  According to the tenth feature of the present invention, since the lost motion mechanism is provided between the input pulley that is the rotating member and the input member of the cam mechanism, the connection pin is moved during the valve closing period of the engine valve. The operation of the cam mechanism, that is, the movement of the shift arm is awaited until it becomes possible, and the connecting pin can be quickly moved when the engine valve is in the valve closing period.

  According to the eleventh feature of the present invention, since the drive mechanism of the throttle valve is connected to the rotating member, a special actuator for inputting power to the shift drive means is unnecessary, and an increase in the number of parts is avoided. At the same time, the cost can be reduced.

  According to the twelfth feature of the present invention, since the governor mechanism that generates axial thrust by the rotation of the camshaft is linked and connected to the shift arm, a special control device for controlling the drive of the shift arm is provided. As unnecessary, the valve operating characteristic changing mechanism can be reliably operated according to the operating state of the engine.

  According to the thirteenth feature of the present invention, the pair of electromagnetic actuators are disposed on the support plate fixed to the cam holder that rotatably supports the camshaft, and rotate between the first and second operating positions. Since both electromagnetic actuators are connected to the link that is linked and connected to the shift arm so as to rotate the link, the drive mechanism that drives the shift arm is compactly configured, and the operation timing of the shift arm, that is, It is possible to arbitrarily set the switching timing of the connection and release of the rocker arm, and the operating characteristics of the internal combustion engine can be expanded.

  Furthermore, according to the fourteenth feature of the present invention, a shift holding spring for holding the first and second operating positions of the link is provided between the link and the support plate, so that the narrow on the cam holder provided in the cylinder head is provided. The shift arm drive mechanism and the shift holding mechanism that elastically holds the operating position of the shift arm can be compactly arranged in the space.

FIG. 3 is a longitudinal sectional view of a main part of the internal combustion engine according to the first embodiment, and is a sectional view taken along line 1-1 of FIG. FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1 when the intake side and exhaust side rocker arms are in a disconnected state. It is a disassembled perspective view of a part of shift drive means and a valve action change mechanism. FIG. 3 is a partially cutaway plan view showing an enlarged main part of FIG. 2. FIG. 5 is a partially cutaway plan view corresponding to FIG. 4 when the intake side and exhaust side rocker arms are in a connected state. It is a figure which shows the relationship between a throttle opening and the operating amount of an input pulley. FIG. 7 is a sectional view taken along line 7-7 in FIG. FIG. 5 is a partially cutaway plan view corresponding to FIG. 4 of the second embodiment. FIG. 6 is a cross-sectional view corresponding to FIG. FIG. 6 is a cross-sectional view corresponding to FIG. It is a top view which expands and shows the principal part of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  A first embodiment of the present invention will be described with reference to FIGS. 1 to 7. First, in FIG. 1, the internal combustion engine is a small-sized one mounted on, for example, a motorcycle, and its engine body 15 A has a piston 16. A cylinder block 18 having a cylinder bore 17 in which a cylinder is slidably fitted and a combustion chamber 21 facing the top of the piston 16 are formed between the cylinder block 18 and a cylinder coupled to the cylinder block 18. A valve chamber 22 is formed between the head 19 and the cylinder head 19, and a head cover 20 </ b> A coupled to the cylinder head 19 is provided.

  The cylinder head 19 is provided with an intake port 23 that can communicate with the combustion chamber 21 and an exhaust port 24 that can communicate with the combustion chamber 21, and can communicate and block the intake port 23 and the combustion chamber 21. An intake valve 25 as an engine valve to be switched and an exhaust valve 26 as an engine valve to switch communication / blocking of the exhaust port 24 and the combustion chamber 21 are disposed in the cylinder head 19 so as to be able to open and close, The valve 25 and the exhaust valve 26 are urged in the valve closing direction by valve springs 27 and 28, respectively. A spark plug 29 is attached to the cylinder head 19 so as to face the top of the combustion chamber 21.

  Referring also to FIG. 2, the valve operating chamber 22 accommodates a valve operating device that opens and closes the intake valve 25 and the exhaust valve 26, and this valve operating device includes a camshaft 31. And first and second intake-side rocker arms 32, 33 interposed between the intake valve 25 and the camshaft 31, and first and second interposed between the exhaust valve 26 and the camshaft 31. Exhaust side rocker arms 34 and 35 are provided.

  The cylinder head 19 is fixedly provided with first and second cam holders 36 and 37 disposed at positions spaced in the direction along the axis of the camshaft 31. The intake valve 25 and the exhaust valve A single camshaft 31 common to the first and second cam holders 36 and 37 is rotatably supported by the first and second cam holders 36 and 37 so as to be disposed between the intake valve 25 and the exhaust valve 26. Of the both ends of the camshaft 31, the end projecting from the second cam holder 37 reduces the rotational power of a crankshaft (not shown) connected to the piston 16 to ½ to reduce the camshaft 31. A driven sprocket 40 that constitutes a part of the timing transmission mechanism 39 that transmits to the gear is fixed, and a cam chain 41 that constitutes a part of the timing transmission mechanism 39 is wound around the driven sprocket 40.

  The first and second intake side rocker arms 32 and 33 are intake side rocker shafts 42 that have an axis parallel to the camshaft 31 and are slidably supported in the axial direction by the first and second cam holders 36 and 37. At least one of the first and second intake side rocker arms 32, 33, in the first embodiment, the first intake side rocker arm 32 is interlocked and connected to the intake valve 25. That is, the tappet screw 44 that contacts the stem end 25a of the intake valve 25 is screwed to the first intake side rocker arm 32 so that the advance / retreat position can be adjusted. The first and second exhaust-side rocker arms 34 and 35 swing on an exhaust-side rocker shaft 43 having an axis parallel to the camshaft 31 at a position where the camshaft 31 is sandwiched between the intake-side rocker shaft 42. The first exhaust-side rocker arm 34 is linked to and connected to the exhaust valve 26 in the first embodiment. That is, the tappet screw 45 that contacts the stem end 26a of the exhaust valve 26 is screwed to the first exhaust-side rocker arm 34 so that the advance / retreat position can be adjusted. Moreover, the exhaust side rocker shaft 43 is also supported by the first and second cam holders 36 and 37 so as to be slidable in the axial direction in the same manner as the intake side rocker shaft 42.

  Thus, the first and second intake side rocker arms 32 and 33 supported so as to be swingable by the intake side rocker shaft 42 and the first and second exhaust side rocker arms supported so as to be swingable by the exhaust side rocker shaft 43. 34 and 35 are arranged in parallel with the second intake side rocker arm 33, the first intake side rocker arm 32, the first exhaust side rocker arm 34 and the second exhaust side rocker arm 35 in this order from the side opposite to the timing transmission mechanism 39. Be placed.

  On the other hand, the camshaft 31 includes first and second intake side cams 46 and 47 respectively corresponding to the first and second intake side rocker arms 32 and 33, and first and second exhaust side rocker arms 34 and 35. First and second exhaust side cams 48 and 49 corresponding to each other are provided, and the first intake side cam 46 and the first exhaust side cam 48 are formed so as to have a cam profile corresponding to the low speed operation of the engine, The second intake side cam 47 and the second exhaust side cam 49 are formed to have a cam profile corresponding to the high speed operation of the engine. That is, the first and second intake side cams 46 and 47 are formed so as to have different cam profiles, and the first and second exhaust side cams 48 and 49 are formed so as to have different cam profiles. Moreover, the first intake-side cam 46 is formed so as to be within the projection range of the second intake-side cam 47 on the projection onto the plane orthogonal to the axis of the camshaft 31, and the first exhaust-side cam 48 is the second It is formed so as to be within the projection range of the exhaust side cam 49.

  Rollers 50 and 51 that are in rolling contact with the first and second intake side cams 46 and 47 are pivotally supported on the first and second intake side rocker arms 32 and 33, respectively. Cylindrical intake side support shafts 54 and 55 for pivotally supporting the first and second intake side rocker arms 32 and 33 so as to open both ends of the intake side support shafts 54 and 55, respectively. These intake side support shafts 54 and 55 are arranged coaxially when the rollers 50 and 51 are in rolling contact with the base circles of the first and second intake side cams 46 and 47. Are provided on the first and second intake side rocker arms 32 and 33, and the axial lengths of both intake side support shafts 54 and 55 are set to be substantially the same as the widths of the first and second intake side rocker arms 32 and 33. Both intake side The inner diameter of the shaft 54 and 55 are set to the same.

  The first and second exhaust-side rocker arms 34 and 35 are rotatably supported by rollers 52 and 53 that are in rolling contact with the first and second exhaust-side cams 48 and 49, respectively. The first and second exhaust-side rocker arms 34 and 35 have cylindrical exhaust-side support shafts 56 and 57 for pivotally supporting the exhaust-side support shafts 56 and 57 so that both ends of the exhaust-side support shafts 56 and 57 are opened. These exhaust-side support shafts 56 and 57 are coaxially arranged in a state where the rollers 52 and 53 are in rolling contact with the base circle portions of the first and second exhaust-side cams 48 and 49. Thus, the first and second exhaust-side rocker arms 34 and 35 are provided with the axial lengths of both exhaust-side support shafts 56 and 57 set to be substantially the same as the widths of the first and second exhaust-side rocker arms 34 and 35. Both exhausts The inner diameter of the support shaft 56, 57 are set to the same.

  The operating characteristics of the intake valve 25 and the exhaust valve 26 are such that the first and second intake-side rocker arms 32 and 33 adjacent to each other and the first and second exhaust-side rocker arms 34 and 35 adjacent to each other are connected and disconnected. Is switched by the valve operating characteristic changing means 60. Thus, when the connection between the first and second intake-side rocker arms 32 and 33 is released and the connection between the first and second exhaust-side rocker arms 34 and 35 is released during low-speed operation of the engine, the first intake-side rocker arm 32 is By swinging following the intake side cam 46, the intake valve 25 opens and closes with an operating characteristic corresponding to the cam profile of the first intake side cam 46, and the first exhaust side rocker arm 34 moves to the first exhaust side cam 48. The exhaust valve 26 opens and closes with an operating characteristic corresponding to the cam profile of the first exhaust side cam 48 by swinging following the movement.

  When the first and second intake-side rocker arms 32 and 33 are connected and the first and second exhaust-side rocker arms 34 and 35 are connected during high-speed operation of the engine, the second intake-side cam 47 is driven to swing. When the first intake side rocker arm 32 swings together with the two intake side rocker arm 33, the intake valve 25 opens and closes with an operating characteristic corresponding to the cam profile of the second intake side cam 47, and is driven by the second exhaust side cam 49. When the first exhaust side rocker arm 34 swings together with the swinging second exhaust side rocker arm 35, the exhaust valve 26 opens and closes with an operating characteristic corresponding to the cam profile of the second exhaust side cam 49.

  By the way, the first intake side rocker arm 32 and the first exhaust side rocker arm 34 are linked to and connected to the intake valve 25 and the exhaust valve 26, respectively, and a valve spring 27 that biases the intake valve 25 and the exhaust valve 26 in the valve closing direction. 28, the rollers 50 and 52 of the first intake-side rocker arm 32 and the first exhaust-side rocker arm 34 are spring-biased to the side that rolls into contact with the first intake-side cam 46 and the first exhaust-side cam 48. The second intake side rocker arm 33 which is separated from the first intake side rocker arm 32 and the second exhaust side rocker arm 35 which is separated from the first exhaust side rocker arm 34 are provided with the valve spring. The spring biasing forces 46 and 48 do not act. Therefore, between the second intake side rocker arm 33 and the head cover 20A, the first intake side rocker arm 33 is biased toward the side where the roller 51 of the second intake side rocker arm 33 rolls into contact with the second intake side cam 47. An intake-side lost motion spring 61 is provided, and a second exhaust-side rocker arm is provided between the second exhaust-side rocker arm 35 and the head cover 20A on the side where the roller 53 of the second exhaust-side rocker arm 35 is brought into rolling contact with the second exhaust-side cam 49. A first exhaust-side lost motion spring 62 for biasing 35 is provided.

  Referring also to FIGS. 3 to 5, the valve operating characteristic changing means 60 switches the first and second intake side rocker arms so as to switch the connection and release of the first and second intake side rocker arms 32 and 33. The first and second engaging portions 32 and 33 are fitted to the first and second intake side rocker arms 32 and 33 while being able to slide in the arrangement direction of the 32 and 33, that is, the axial direction of the intake side rocker shaft 42. The arrangement direction of the first and second exhaust side rocker arms 34 and 35, that is, the exhaust side rocker shaft, by switching the connection and release of the connection between the two intake side connection pins 63 and 64 and the first and second exhaust side rocker arms 34 and 35. 43. First and second exhausts that are brought into contact with each other and fitted to the first and second exhaust-side rocker arms 34 and 35 while being able to slide in the axial direction of 43. The first and second connecting pins 65, 66 are in contact with and engaged with the outer ends of the second intake side connecting pins 64, which are intake side connecting pins at one end in the arrangement direction of the first and second intake side connecting pins 63, 64. The shift arm 67 contacts and engages with the outer end of the first intake side connection pin 63 which is the intake side connection pin at the other end in the arrangement direction of the first and second intake side connection pins 63, 64, and A second shift arm 68 that contacts and engages with the outer end of the first exhaust side connection pin 65, which is an exhaust side connection pin at one end in the arrangement direction of the second exhaust side connection pins 65, 66; A third shift arm 69 that contacts and engages with the outer end of the second exhaust side connection pin 66, which is the exhaust side connection pin at the other end in the arrangement direction of the exhaust side connection pins 65, 66; Arm 67, second shift arm 68, and third shift arm 69 are Linked to those of the rocker shaft 43 so as to operate with gas side rocker shaft 42 and the exhaust-side rocker shaft 43, is connected to move in conjunction with the arrangement direction of the rocker arms 32 to 35.

  The first and second intake-side connecting pins 63 and 64 are cylindrical intake-side support shafts 54, fixed to the first and second intake-side rocker arms 32 and 33 so as to support the rollers 50 and 51. 55 is slidably fitted in the first and second intake side connection pins 63, 64 that are in contact with each other, and are first and second intake side connection pins 63, which are connection pins at both ends in the arrangement direction. The first and second intakes 64 protrude from the first and second intake-side rocker arms 32, 33 in response to switching between connection and release of the first and second intake-side rocker arms 32, 33. The axial lengths of the intake side connecting pins 63 and 64 are set. In the first embodiment, the axial length of the first intake side connecting pin 64 is set to be substantially the same as the width of the first intake side rocker arm 32, whereas the axial length of the second intake side connecting pin 64 is set. Is set larger than the width of the second intake side rocker arm 33. Thus, the inner ends of the first and second intake side connecting pins 63 and 64 that are in contact with each other are in the center between the first and second intake side rocker arms 32 and 33, and the first and second intake side rocker arms are located. In the state where 32 and 33 are not connected as shown in FIG. 4, the outer end of the second intake side connection pin 64 protrudes outward from the second intake side rocker arm 33, and the second intake side connection pin 64 is In a state where the first and second intake side rocker arms 32 and 33 are connected by being fitted in the intake side support shaft 54 of the first intake side rocker arm 32, as shown in FIG. The outer ends of the first and second intake side rocker arms 32 protrude outward.

  The first and second exhaust-side connecting pins 65 and 66 support the first and second exhaust-side rocker arms 34 and 66 so as to pivotally support the rollers 52 and 53 that are in rolling contact with the first and second exhaust-side cams 48 and 49. The first and second exhaust-side connection pins 65 and 66 that are slidably fitted in cylindrical exhaust-side support shafts 56 and 57 fixed to the shaft 35 are connected at both ends in the arrangement direction. The first and second exhaust-side connecting pins 65 and 66, which are pins, are alternatively used as the first and second exhaust-side rocker arms in response to switching between connection and release of the first and second exhaust-side rocker arms 34 and 35. The axial lengths of the first and second exhaust-side connecting pins 65 and 66 are set so as to protrude from 34 and 35. In the first embodiment, the axial length of the first exhaust side connecting pin 65 is set to be substantially the same as the width of the first exhaust side rocker arm 34, whereas the axial length of the second exhaust side connecting pin 65 is set. Is set larger than the width of the second exhaust-side rocker arm 35. Thus, the inner ends of the first and second exhaust side connecting pins 65 and 66 that are in contact with each other are in the center between the first and second exhaust side rocker arms 34 and 35, and the first and second exhaust side rocker arms are located. In a state where the pipes 34 and 35 are not connected as shown in FIG. 4, the outer end of the first exhaust side connection pin 65 protrudes outward from the first exhaust side rocker arm 34, and the first exhaust side connection pin 65 Is fitted into the exhaust-side support shaft 57 of the second exhaust-side rocker arm 35 and the first and second exhaust-side rocker arms 34 and 35 are connected, as shown in FIG. The outer end of 66 protrudes outward from the second exhaust side rocker arm 35.

  A driving force is transmitted to the first shift arm 67, the second shift arm 68, and the third shift arm 69 by the shift driving means 70. The shift driving means 70 is a cylinder of the engine body 15A. An input pulley 71 that is a rotating member that is rotatably supported by the head 19, and a first shift arm 67, a second shift arm 67 that moves the input pulley 71 along the arrangement direction of the rocker arms 32 to 35. And a cam mechanism 72 adapted to convert the movement of the shift arm 68 and the third shift arm 69, and disposed on the opposite side of the timing transmission mechanism 39. Thus, a portion of the cylinder head 19 that rotatably supports the input pulley 71 is formed to protrude upward so as to bite into the head cover 20A side.

  A drive cable 73 connected to a throttle valve drive mechanism (not shown) is wound around and connected to the input pulley 71. As shown in FIG. 6, the input pulley 71 rotates within a predetermined throttle opening range. The rotational power from the drive mechanism is transmitted to the input pulley 71 so as to operate, and the cam mechanism 72 is switched at a predetermined throttle opening.

  The rotation shaft 74 has an axis parallel to the camshaft 31 and is rotatably supported by the cylinder head 19. Between the cylinder head 19 and the rotation shaft 74, a ball bearing 75 and an annular shape are provided. The seal member 76 is interposed. Outside the cylinder head 19, the pivot shaft 74 is provided with a shaft portion 74 a having a pair of flat surfaces 77... Formed on a part of the outer periphery thereof coaxially and integrally. The shaft 74a is supported so as to be relatively rotatable.

  In the shift driving means 70, power is transmitted from the input pulley 71 to the rotating shaft 74 of the cam mechanism 72, and the lost motion mechanism 78 is in the middle of this power transmission path, that is, between the input pulley 71 and the rotating shaft 74. Is provided.

  Referring also to FIG. 7, a fan-shaped power transmission member 79 that is opposed to the input pulley 71 from the outer side is fixed to the support shaft portion 74 a, and the power transmission member 79 includes the above-described power transmission member 79. An arcuate opening 80 centering on the axis of the rotation shaft 74 is provided.

  The lost motion mechanism 78 includes a second lost motion spring 81 provided between the input pulley 71 and a power transmission member 79 fixed to the rotating shaft 74, and this second lost motion. The spring 81 includes a coil portion 81a that surrounds the support shaft portion 74a between the input pulley 71 and the power transmission member 79, a pair of scissors portions 81b and 81b extending from both ends of the coil portion 81a, and the coil It has the engaging part 81c extended on the opposite side to the said scissors part 81b ... from the intermediate part of the part 81a.

  The input pulley 71 is provided with a pressing protrusion 82 so that the tip end is inserted into the opening 80, and both scissors 81b of the second lost motion spring 81 are connected to the pressing protrusion 82 on both sides. It is arranged at a position sandwiched between. Further, the engaging portion 81 c of the second lost motion spring 81 is engaged with a locking protrusion 83 protruding from the input pulley 71. Further, the power transmission member 79 is provided with a pressure receiving projection 84 that is sandwiched between the two scissors 81 b of the second lost motion spring 81.

  According to such a lost motion mechanism 78, when the input pulley 71 rotates while the rotation of the rotation shaft 74 and the power transmission member 79 is restricted, the second lost motion spring 81 When one of the scissors 81b is pushed by the pressing projection 82, the scissor angle between the other scissors 8b is widened and the power transmission member 79 is left behind, and the input pulley 71 and Between the power transmission members 79, a spring biasing force on the side that reduces the scissor angle of the scissors 81b.

  3 to 5 again, the intake side and the exhaust side rocker shafts 42 and 43 have an insertion hole 88 disposed outside the first cam holder 36 and through which the rotation shaft 74 is inserted. A movable connecting member 87 extending in a direction perpendicular to the axis of the movable connecting member 87 is disposed, and the intake side and exhaust side rocker shafts 42 and 43 are fixed to both longitudinal ends of the movable connecting member 87 by screw members 85 and 86. Is done.

  The cam mechanism 72 is provided between the rotating shaft 74 and the movable connecting member 87, and includes a cam groove 89 provided on the outer periphery of the rotating shaft 74 and the cam groove 89 within the insertion hole 88. And a pin 90 fixed to the movable connecting member 87 so as to fit the inner end thereof. Moreover, the cam groove 89 causes the pin 90, that is, the movable connecting member 87 to move in the axial direction of the rotation shaft 74, that is, the intake side and the exhaust side rocker shafts 42, 43 according to the rotation of the rotation shaft 74. It is formed to move.

  The second shift arm 68 includes a cylindrical first support cylinder 68a that allows the intake-side rocker shaft 42 to pass therethrough, a cylindrical second support cylinder 68b that allows the exhaust-side rocker shaft 43 to pass through, And an abutting engagement portion 68c installed between the second support cylinder portions 68a and 68b. The first and second support cylinder portions 68a and 68b are connected to the intake side and the exhaust by pins 91 and 92, respectively. The second shift arm 68 is fixed to the side rocker shafts 42 and 43, and moves together with the intake side and exhaust side rocker shafts 42 and 43. Further, both surfaces of the contact engagement portion 68c are in contact with and engaged with the outer end of the first intake side connection pin 63 and the outer end of the first exhaust side connection pin 65.

  The first shift arm 67 is supported on the intake side rocker shaft 42 so as to be movable in the axial direction so as to prevent relative rotation of the second shift arm 68 with the first support cylinder 68a. The third shift arm 69 is supported by the exhaust rocker shaft 43 so as to be movable in the axial direction so that the second shift arm 68 is prevented from rotating relative to the second support cylinder 68b.

  That is, the second shift arm 68 that is one of the second shift arm 68 and the first shift arm 67 that make a pair on the intake valve 25 side, and the second shift that makes a pair on the exhaust valve 26 side. A second shift arm 68, which is one of the arm 68 and the third shift arm 69, is fixed to the intake side and exhaust side rocker shafts 42 and 43, which are moving bodies connected to the shift driving means 70. The

  Further, between the second shift arm 68 and the second shift arm 68, which is the other shift arm of the second shift arm 68 and the first shift arm 67 paired on the intake valve 25 side, When the intake side and exhaust side rocker shafts 42 and 43 are moved from the first shift arm 67 to the side where the pressing force is applied to the second intake side connecting pin 64, the first shift arm 68 is moved in the first direction. A third intake-side lost motion spring 93 that is a pulling spring is provided so as to exert a spring force that follows the shift arm 67, and a second shift arm 68 and a third shift arm that are paired on the exhaust valve 26 side. The third shift arm 69 and the second shift arm 68 are pressed against the second exhaust-side connecting pin 66 between the third shift arm 69 and the second shift arm 68. When the intake side and exhaust side rocker shafts 42 and 43 are moved to the side on which the third shift arm 69 is caused to act, a pulling spring is used to exert a spring force that causes the third shift arm 69 to follow the movement of the second shift arm 68. A third exhaust-side lost motion spring 94 is provided.

  Between the movable connecting member 87 and the first cam holder 36 in the shift driving means 70, the second shift arm 68 is connected to the first and second intake side rocker arms 32, 33 and the first and second exhaust side rocker arms 34, 35. A shift holding mechanism 97 that elastically holds the operating position for releasing the connection and the operating positions for connecting the first and second intake-side rocker arms 32, 33 and the first and second exhaust-side rocker arms 34, 35. Provided.

  The shift holding mechanism 97 includes a lever 99 that has a long hole 98 through which the outer end of the pin 90 in the cam mechanism 72 is inserted, and is rotatably supported by the first cam holder 36. A spring 100 that is contracted between the cam holders 36.

  One end of the lever 99 has an axis perpendicular to the axis of the exhaust rocker shaft 43 and is rotatably supported on the exhaust rocker shaft 43 side of the first cam holder 36 via a support shaft 101. The hole 98 is provided at the other end of the lever 99. The spring 100 is contracted between a fixed spring receiving portion 102 provided near the intake side rocker shaft 42 of the first cam holder 36 and a movable spring receiving portion 99a provided in an intermediate portion of the lever 99. The position of the lever 99 is held elastically by the displacement of the movable spring receiving portion 99a from the virtual straight line L1 connecting the center of the support shaft 101 and the center of the fixed spring receiving portion 102. Since the pin 90 is inserted into the long hole 98, the positions of the movable connecting member 87, the intake side rocker shaft 42, the exhaust side rocker shaft 43, and the second shift arm 68 are held elastically.

  Next, the operation of the first embodiment will be described. The valve operating characteristic changing means 60 capable of changing the operating characteristics of the intake valve 25 and the exhaust valve 26 includes first and second intake side rocker arms 32 arranged adjacent to each other. , 33 can be slid in the arrangement direction of the first and second intake side rocker arms 32, 33 so as to switch the connection and release of the connection, and are fitted to the intake side rocker arms 32, 33 while being abutted with each other. The first and second intake side connecting pins 63, 64 and the first and second exhaust side rocker arms 34, 35 arranged adjacent to each other are switched to be connected and disconnected. The first and second exhausts that are brought into contact with each other and are fitted to the exhaust side rocker arms 34 and 35 while allowing the exhaust side rocker arms 34 and 35 to slide in the arrangement direction. A first shift arm 67 that contacts and engages the outer end of the second intake side connection pin 33 on one end side in the arrangement direction of the first and second intake side connection pins 32 and 33; The first and second intake side connection pins 32, 33 are in contact with and engaged with the outer ends of the first intake side connection pins 32 on the other end side in the arrangement direction, and the first and second exhaust side connection pins 34, The second shift arm 68 that contacts and engages with the outer end of the first exhaust side connection pin 65 on one end side of the arrangement direction of the 35, and the other end in the arrangement direction of the first and second exhaust side connection pins 64, 65 And a third shift arm 69 that contacts and engages with the outer end of the second exhaust side connecting pin 65 on the side. In addition, the first and second intake side connection pins 63 and 64 at both ends in the arrangement direction of the first and second intake side connection pins 63 and 64 that are in contact with each other are connected to the first and second intake side rocker arms 32 and 33. The first and second exhaust-side connecting pins 65 and 66 that protrude from the first and second intake-side rocker arms 32 and 33 alternatively according to the switching of the connection release and are in contact with each other are arranged in the first direction. And the second exhaust-side connecting pins 65 and 66 protrude from the first and second exhaust-side rocker arms 34 and 35 alternatively in response to switching between connection and disconnection of the first and second exhaust-side rocker arms 34 and 35. The first shift arm 67, the second shift arm 68, and the third shift arm 69 move in conjunction with the arrangement direction of the intake side and exhaust side rocker arms 32-35. In conjunction with way, it has been linked.

  Therefore, it is possible to change the valve operating characteristics of the intake valve 25 and the exhaust valve 26 by driving the first shift arm 67, the second shift arm 68, and the third shift arm 69 that are linked to each other. High hydraulic pressure is not required to drive the first and second intake side connection pins 64, 64 and the first and second exhaust side connection pins 65, 66, and valves for controlling the high hydraulic pressure are not required. The valve operation characteristic changing mechanism 60 can be easily applied to an internal combustion engine having a rolling bearing type crankshaft or a small internal combustion engine while avoiding an increase in cost. In addition, when changing the valve operating characteristics of the intake valve 25 and the exhaust valve 26, the second shift arm 68 is common to the intake valve 25 side and the exhaust valve 26 side, so that the number of parts can be reduced and the structure can be simplified. .

  The first and second intake side connecting pins 63 and 64 support the first and second intake side rocker arms 32 so as to pivotally support the rollers 50 and 51 that are in rolling contact with the first and second intake side cams 46 and 47. , 33 are slidably fitted into cylindrical intake side support shafts 54, 55 fixed to the first and second exhaust side connecting pins 65, 66. Fits slidably into cylindrical exhaust-side support shafts 56 and 57 fixed to the first and second exhaust-side rocker arms 34 and 35 so as to support the rollers 52 and 53 that are in rolling contact with 48 and 49. Therefore, the first and second intake-side rocker arms 32 and 33 and the first and second exhaust-side rocker arms 34 and 35 have a dedicated space for arranging the connecting pins 63 to 66. As unnecessary, before It can contribute to miniaturization of the rocker arms 32 to 35.

  The first and second intake side rocker arms 32 and 33 have an axis parallel to the camshaft 31 and are rocked by an intake side rocker shaft 42 slidably supported by the first and second cam holders 36 and 37 of the cylinder head 19. The first and second exhaust-side rocker arms 34 and 35 have an axis parallel to the camshaft 31 and the intake-side rocker shaft 42, and are slidably supported by the first and second cam holders 36 and 37. The first shift arm 67, the second shift arm 68, and the third shift arm 69 are operated together with the intake side and exhaust side rocker shafts 42, 43. In this way, the rocker shafts 42 and 43 are interlocked and connected to each other, so that the first shift door Arm 67, the structure for driving the second shift arm 68 and the third shift arm 69 is simplified, it is possible to reduce the number of parts.

  Further, since the shift driving means 70 including the lost motion mechanism 78 is linked and connected to the first shift arm 67, the second shift arm 68, and the third shift arm 69, the intake valve 25 and the exhaust valve 26 are closed. The movement of the first shift arm 67, the second shift arm 68, and the third shift arm 69 is waited until the connection pins 63 to 65 can be moved in a period, and the intake valve 25 and the exhaust valve The connection pins 63 to 65 can be quickly moved when the valve 26 is closed.

  In addition, between the first shift arm 67 and the second shift arm 68 of the second shift arm 68 and the first shift arm 67 paired on the intake valve 25 side, the first shift arm 67 is provided. The first shift arm 67 is caused to follow the movement of the second shift arm 68 when the intake side and exhaust side rocker shafts 42 and 43 move to the side where the pressing force is applied to the second intake side connecting pin 64 from the first side. A third intake-side lost motion spring 93 that exerts a spring force is provided, and the second shift arm 68 and the third shift arm 69 of the third shift arm 69 paired on the exhaust valve 26 side, Between the shift arm 68, the intake side and exhaust side rocker shafts 42, 43 move from the third shift arm 69 to the side where the pressing force is applied to the second exhaust side connection pin 66. When the second shift arm 68 is moved, the third exhaust arm lost motion spring 94 is provided which exerts a spring force that causes the third shift arm 69 to follow the movement of the second shift arm 68. When the second intake side connecting pin 64 is moved by pressing the pin 64, and when the second exhaust side connecting pin 66 is moved by pressing the second exhaust side connecting pin 66 by the third shift arm 69, The first shift arm 67 and the third shift arm until the second intake-side connecting pin 64 and the second exhaust-side connecting pin 66 can be moved when the intake valve 25 and the exhaust valve 26 are closed. 69, the second intake side connection pin 64 and the second exhaust side connection pin 66 can be moved quickly when the intake valve 25 and the exhaust valve 26 are closed.

  The first and second intake-side rocker arms 32 and 33 and the first and second exhaust-side rocker arms 34 and 35 are disengaged from each other, the first and second intake-side rocker arms 32 and 33, and the first and second intake-side rocker arms 32 and 33. Since the operation position where the exhaust-side rocker arms 34 and 35 are connected is resiliently held by the shift holding mechanism 97, it is possible to ensure the reliability of the operation.

  Further, the shift driving means 70 is configured to change the rotational movement of the input pulley 71 rotatably supported by the cylinder head 19 of the engine main body 15A along the arrangement direction of the rocker arms 32, 33, 34, 34. 67, since it has the cam mechanism 72 adapted to convert the movement of the second shift arm 68 and the third shift arm 69, the driving force input to the input pulley 71 from the external operation or the actuator is the first. The shift arm 67, the second shift arm 68, and the third shift arm 69 can be easily converted into a linear movement, so that the shift drive means 70 can be made compact and the operation reliability can be ensured. it can.

  Further, since the lost motion mechanism 78 is provided between the input pulley 71 around which the drive cable 73 is wound around the outer periphery and the rotating shaft 74 that is the input member of the cam mechanism 72, the intake valve 25 and the exhaust valve 26 are closed. The operation of the cam mechanism 72, that is, the movement of the second shift arm 68 is waited until the connection pins 63 to 66 can move, and the intake valve 25 and the exhaust valve 26 are closed. Sometimes, the connecting pins 63 to 66 can be moved quickly.

  In addition, since the drive mechanism of the throttle valve is connected to the input pulley 71 so that the cam mechanism 72 is switched at a predetermined throttle opening, a special actuator for inputting power to the shift drive means 70 is not required. In addition, it is possible to avoid an increase in the number of parts and to reduce the cost.

  A second embodiment of the present invention will be described with reference to FIG. 8, but the portions corresponding to the first embodiment in FIGS. 1 to 7 are only given the same reference numerals and are not illustrated in detail. To do.

  Of the second shift arm 68 and the first shift arm 67 paired on the intake valve 25 side, the first shift arm 67 and the first cam holder provided on the cylinder head 19 constituting a part of the engine body 15A. 36, the second shift arm when the intake side and exhaust side rocker shafts 42 and 43 move from the first shift arm 67 to the side where the pressing force is applied to the second intake side connecting pin 64. The second shift arm is provided with a third intake-side lost motion spring 104 that is a push spring so as to exert a spring force that causes the first shift arm 67 to follow the movement of 68, and forms a pair on the exhaust valve 26 side. 68 and the third shift arm 69, the third shift arm 69, which is the other shift arm, and the cylinder head 19 constituting a part of the engine body 15A. When the intake side and exhaust side rocker shafts 42, 43 move between the second cam holder 37 and the side where the third shift arm 69 applies the pressing force to the second exhaust side connection pin 66, the second cam holder 37 moves to the second cam holder 37. A third exhaust-side lost motion spring 105, which is a push spring, is provided so as to exert a spring force that causes the third shift arm 69 to follow the movement of the shift arm 68.

  The same effects as those of the first embodiment can be obtained by the second embodiment.

  A third embodiment of the present invention will be described with reference to FIG. 9, but the portions corresponding to the first embodiment of FIGS. 1 to 7 are only denoted by the same reference numerals, and detailed description thereof is omitted. To do.

  A governor mechanism 106 that generates axial thrust by rotation of the camshaft 31 is connected to an end portion of the camshaft 31 opposite to the timing transmission mechanism 39, and a head cover that constitutes a part of the engine body 15B. 20B is provided with an opening 107 corresponding to the governor mechanism 106, and a lid member 108 for closing the opening 107 is attached to the head cover 20B.

  The governor mechanism 106 is a movable connection in which the first shift arm 67, the second shift arm 68, and the third shift arm 69 are fixedly coupled to the intake side rocker shaft 42 and the exhaust side rocker shaft 43, which are linked and connected. The member 87 is moved in accordance with a change in the engine speed. When the engine speed increases, the movable connecting member 87 moves closer to the first cam holder 36, whereby the valve operating characteristic changing means 60 is changed. The first and second intake-side rocker arms 32 and 33 are connected, the first and second exhaust-side rocker arms 34 and 35 are connected, and the intake valve 25 and the exhaust valve 26 correspond to the high-speed operation of the engine. The cam 47 and the second exhaust side cam 49 are opened and closed with characteristics corresponding to the cam profiles.

  According to the third embodiment, a special control device for controlling the driving of the first shift arm 67, the second shift arm 68, and the third shift arm 69 is not required, and it depends on the operating state of the engine. The valve operation characteristic changing mechanism 60 can be reliably operated.

  A fourth embodiment of the present invention will be described with reference to FIGS. 11 and 12, but the portions corresponding to the first embodiment in FIGS. Description is omitted.

  A support plate 110 is interposed between cam holders 36 and 37 provided on the cylinder head 19 so as to rotatably support the camshaft 31 and the camshaft 31 between the combustion chamber 21 (see FIG. 1). A pair of electromagnetic actuators 111 and 112 are fixed to the support plate 110 and can be rotated between the first and second operating positions, and the first shift arm 67, the second shift arm 68, and The electromagnetic actuators 111 and 112 are connected to a link 113 linked and connected to the third shift arm 69 so as to rotate the link 113.

  The link 113 includes a link base portion 113a that supports the link 113 on the support plate 110 via a support shaft 114, and a first shaft that is disposed on one diameter line of the support shaft 114 and extends from the link base portion 113a to both sides. The second arm portions 113b and 113c are integrally provided.

  On the other hand, both electromagnetic actuators 111 and 112 have rods 111a and 112a that expand and contract by energization and de-energization. These electromagnetic actuators 111 and 112 extend in the direction in which the first and second arm portions 113b and 113c extend. At positions spaced apart, the longitudinal directions of the first and second arm portions 113b and 113c are made substantially perpendicular to the expansion and contraction direction of the rods 111a and 112a, while the first and second arm portions 113b and 113c It arrange | positions in the position facing a front-end | tip.

  The rod 111a of one electromagnetic actuator 111 is connected to the tip of the first arm 113b via a fourth lost motion spring 115, and the rod 112a of the other electromagnetic actuator 112 is connected to the tip of the second arm 113c in the fifth lost motion. It is connected via a spring 116. Thus, the link 113 rotates about the axis of the support shaft 114 by selectively switching between energization and de-energization of the electromagnetic actuators 111 and 112.

  By the way, a second shift arm in which a third intake side lost motion spring 93 is provided between the first shift arm 67 and a third exhaust side lost motion spring 94 is provided between the third shift arm 69 and the first shift arm 67. A connecting pin 117 that penetrates the support plate 110 is fixed to 68 so as to be able to move in the direction along the axis of the intake side and exhaust side rocker shafts 42 and 43. The link 113 integrally has a connecting arm portion 113d extending from the link base portion 113a in a direction orthogonal to the longitudinal direction of the first and second arm portions 113b and 113c, and the tip of the connecting arm portion 113d. The connecting pin 117 is inserted into the long hole 118 provided in the hole.

  Therefore, by selectively switching between energization and de-energization of the electromagnetic actuators 111 and 112, the link 113 rotates around the axis of the support shaft 114, so that the second shift arm 68 is moved to the intake side and the exhaust. Driven in the direction along the axis of the side rocker shafts 42 and 43, the link 113 releases the connection between the first and second intake side rocker arms 32 and 33 and the first and second exhaust side rocker arms 34 and 35. Between the first operating position (the operating position shown in FIG. 10) and the second operating position where the first and second intake-side rocker arms 32, 33 and the first and second exhaust-side rocker arms 34, 35 are connected. Will move.

  A shift holding spring 119 for holding the first and second operating positions of the link 113 is provided between the link 113 and the support plate 110, and is opposite to the connecting arm portion 113d. Thus, a shift holding spring 119 having a coil shape is contracted between the movable spring receiving portion 113e protruding from the link base portion 113a and the fixed spring receiving portion 120 provided on the support plate 110.

  Thus, the first and second operating positions of the lever 113 are held elastically by moving the movable spring receiving portion 113e from a virtual straight line L2 connecting the center of the support shaft 104 and the center of the fixed spring receiving portion 120. .

  According to the fourth embodiment, the pair of electromagnetic actuators 111 and 112 are disposed on the support plate 110 fixed to the first and second cam holders 36 and 37, and rotate between the first and second operation positions. The electromagnetic actuators 111 and 112 rotate the link 113 to the link 113 linked and connected to the first shift arm 67, the second shift arm 68, and the third shift arm 69. Since they are connected, a drive mechanism for driving the first shift arm 67, the second shift arm 68, and the third shift arm 69 is compactly configured, and the first shift arm 67, the second shift arm 68, and The operation timing of the third shift arm 69, that is, the first and second intake side rocker arms 32 and 33 and the first and second exhaust side rocker arms. The switching timing of connecting and disconnecting the arm 34 and 35 it is possible to arbitrarily set, it is possible to widen the operating characteristics of the internal combustion engine.

  Further, since a shift holding spring 119 for holding the first and second operating positions of the link 113 is provided between the link 113 and the support plate 110, the first and second cam holders 36 and 37 provided on the cylinder head 19 are provided. Drive mechanism of the first shift arm 67, the second shift arm 68, and the third shift arm 69, and a shift holding mechanism that elastically holds the operating positions of the shift arms 67 to 69 in a narrow space Can be arranged compactly.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. Is possible.

  For example, in the above embodiment, the rollers 50 and 51 that are in rolling contact with the first and second intake side cams 46 and 47 are pivotally supported by the first and second intake side rocker arms 32 and 33, and the first and second exhaust side The case where the rollers 52 and 53 that are in rolling contact with the cams 48 and 49 are pivotally supported by the first and second exhaust-side rocker arms 34 and 35 has been described. However, in the present invention, the cam slipper that contacts each cam is provided with each rocker arm. The present invention is also applicable to a variable valve operating device for an internal combustion engine provided in the engine. In that case, each connecting pin is disposed at an arbitrary position on the back side of each cam slipper.

  In the above embodiment, the operating characteristics of the intake valve 25 and the exhaust valve 26 are changed by the valve operating characteristic changing means 60 common to the valves 25 and 26. The present invention can also be applied to a variable valve operating apparatus for an internal combustion engine in which individually corresponding valve operating characteristic changing means is provided.

  In addition, when applied to an internal combustion engine mounted on a vehicle having a transmission such as a belt converter, the shift arm can be driven by a variable sheave of a belt pulley. It is also possible to drive the shift arm with an actuator so that the valve operating characteristics can be switched at the number of revolutions.

15A, 15B ... Engine body 25 ... Intake valve 26 as engine valve ... Exhaust valve 31 as engine valve ... Camshafts 32, 33 ... Intake side rocker arms 34, 35 ... Exhaust Side rocker arms 36, 37 ... cam holder 42 ... moving side intake side rocker shaft 43 ... moving side exhaust side rocker shaft 46, 47 ... intake side cams 48, 49 ... exhaust side Cams 50, 51, 52, 53 ... Rollers 54, 55 ... Intake side support shafts 56, 57 ... Exhaust side support shafts 60 ... Valve operation characteristic changing means 63, 64 ... Intake side connection Pin 65, 66 ... exhaust side connecting pin 67 ... first shift arm 68 ... second shift arm 69 ... third shift arm 70 ... shift driving means 71 ... times Input pulley 72 ... cam which is a moving member Structure 73 ... Drive cable 74 ... Rotating shaft 78 as an input member ... Lost motion mechanism 93,104 ... Third intake side lost motion springs 94,105 ... Lost motion springs 3rd exhaust side lost motion spring 97 which is a motion spring ... shift holding mechanism 106 ... governor mechanism 110 ... support plates 111, 112 ... electromagnetic actuator 113 ... link 119 ... for shift holding Spring

Claims (14)

  A camshaft (31) provided with a plurality of cams (46, 47; 48; 49) having different cam profiles, and a plurality of the cams (46, 47; 48; 49) individually contacting the camshafts (31) is arranged adjacent to and arranged in a direction parallel to the axis of the camshaft (31) while being able to oscillate around an axis parallel to (31), and at least one is linked and connected to the engine valves (25, 26). Operating characteristics of the engine valve (25, 26) by switching the connection and release of the rocker arms (32, 33; 34, 35) adjacent to each other and the rocker arms (32, 33; 34, 35) adjacent to each other. In the variable valve operating apparatus for an internal combustion engine, the valve operating characteristic changing means (60) includes a plurality of rocker arms (32, 33; 3). , 35) can be slid in the arrangement direction of the rocker arms (32, 33; 34, 35) so as to switch the connection and release of the rocker arms, and are brought into contact with each other, and the rocker arms (32, 33; 34, 35) and a plurality of connecting pins (63, 64; 65, 66) and connecting pins (63, 64; 65) at both ends of the connecting pins (63, 64; 65, 66) in the arrangement direction. , 66) and a shift arm (67.66) which is paired so as to abut and engage with the axial outer ends thereof and which can move in conjunction with the arrangement direction of the rocker arms (32,33; 34,35). 68; 68, 69), and among the connecting pins (63, 64; 65, 66) in contact with each other, the connecting pins (63, 64; 65, 66) at both ends in the arrangement direction are at both ends thereof. Connecting pins (63, 64 65, 66) so as to project alternatively from the rocker arms (32, 33; 34, 35) to which the plurality of rocker arms (32, 33; 34, 35) are connected and disconnected. A variable valve operating apparatus for an internal combustion engine, characterized in that an axial length of each of the connecting pins (63, 64; 65, 66) is set.   A cylindrical support shaft (54) that rotatably supports rollers (50, 51; 52, 53) that are individually in rolling contact with a plurality of cams (46, 47; 48; 49) provided on the camshaft (31). , 55; 56, 57) are fixed to the respective rocker arms (32, 33; 34, 35), respectively, and the connecting pins (63, 64; 65, 66) are supported on their support shafts (54, 55; 56, 57). 57) The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the variable valve operating apparatus is slidably fitted into the internal combustion engine.   A plurality of rocker arms (32, 33; 34, 35) having an axis parallel to the camshaft (31) and capable of sliding in the axial direction of the rocker are supported on the engine body (15A, 15B). The shaft (42, 43) is swingably supported, and the shift arm (67, 68, 69) is interlocked with the rocker shaft (42, 43) so as to operate together with the rocker shaft (42, 43). The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the variable valve operating apparatus is connected.   Shift drive linked to and coupled to the shift arm (67, 68, 69) by moving the shift arm (67, 68, 69) in the direction of arrangement of the rocker arms (32, 33; 34, 35). The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein a lost motion mechanism (78) is interposed in the power transmission path of the means (70).   One of the paired shift arms (67, 68; 68, 69) (68) can move in the direction of arrangement of the rocker arms (32, 33; 34, 35), and the shift drive means (70 Between the other shift arm (67, 69) and the one shift arm (68) or the engine body (15A, 15B). When the movable body (42, 43) moves from the other shift arm (67, 69) to the side where the pressing force is applied to the connecting pin (64, 66), the one shift arm (68) moves. 5. A variable valve operating apparatus for an internal combustion engine according to claim 4, wherein a lost motion spring (93, 94; 104, 105) for following the other shift arm (67, 69) is provided.   A plurality of intake side cams (46, 47) and exhaust side cams (48, 49) each having a different cam profile are provided, and a single unit arranged in common for the intake valve (25) and the exhaust valve (26). The camshaft (31) and the plurality of intake side cams (46, 47) are individually brought into contact with each other and can swing around an axis parallel to the cam shaft (31), while the cam shaft (31). A plurality of intake-side rocker arms (32, 33) that are arranged adjacent to each other in a direction parallel to the axis of the intake and that are linked and connected to the intake valve (25), and a plurality of the exhaust-side cams (48, 49). Are arranged adjacent to each other in the direction parallel to the axis of the camshaft (31) while being able to swing individually around the axis parallel to the camshaft (31) and at least Connection and connection of a plurality of exhaust side rocker arms (34, 35), one of which is linked and connected to the exhaust valve (26), and the intake side and exhaust side rocker arms (32, 33; 34, 35) adjacent to each other. In a variable valve operating apparatus for an internal combustion engine, comprising a valve operating characteristic changing means (60) capable of changing operating characteristics of the intake valve (25) and the exhaust valve (26) by switching release, the valve operating characteristic change The means (60) can slide in the arrangement direction of the intake side rocker arms (32, 33) while switching the connection and release of the plurality of intake side rocker arms (32, 33). A plurality of intake side connecting pins (63, 64) which are brought into contact with the intake side rocker arms (32, 33) and connected to the plurality of exhaust side rocker arms (34, 35). The exhaust side rocker arms (34, 35) can be slid in the arrangement direction so as to switch the connection and release, and are brought into contact with each other and fitted to the exhaust side rocker arms (34, 35). A first shift that contacts and engages the outer ends of the plurality of exhaust side connection pins (65, 66) and the intake side connection pins (63) at one end in the arrangement direction of the plurality of intake side connection pins (63, 64). The arm (67) is in contact with and engaged with the outer end of the intake side connection pin (64) at the other end in the arrangement direction of the plurality of intake side connection pins (63, 64), and the plurality of exhaust side connection pins ( A second shift arm (68) that contacts and engages with the outer end of the exhaust-side connecting pin (65) at one end in the arrangement direction of 65, 66), and an array of the plurality of exhaust-side connecting pins (65, 66). The second end is in contact with and engaged with the outer end of the exhaust side connecting pin (66) at the other end 3 of the intake side and exhaust side connection pins (63, 64; 65, 66) in contact with each other, the intake side and exhaust side connection pins (63, 64) at both ends in the arrangement direction. 63, 64; 65, 66) are connected to the intake side and the exhaust side rocker arms (32, 33) in which the intake side and exhaust side connection pins (63, 64; 65, 66) of both ends thereof are fitted. 34, 35) each of the connecting pins (63, 64;) so as to project alternatively according to the connection and release of the plurality of intake side and exhaust side rocker arms (32, 33; 34, 35). 65, 66) is set, and the first to third shift arms (67-69) are interlocked with the arrangement direction of the intake side and exhaust side rocker arms (32, 33; 34, 35). Then move Manner interlocked variable valve device for an internal combustion engine, characterized in that it is connected.   Shift drive means (70) having a lost motion mechanism (78) interposed in the power transmission path is arranged to arrange the second shift arm (68) in the intake side and exhaust side rocker arms (32, 33: 34, 35). The first and third shift arms (67, 69) and the second shift arm (68) or engine body (15A, 15B) are connected to the second shift arm (68) so as to move in the direction. And a lost motion spring (93, 94; 104, 105) for making the first and third shift arms (67, 69) follow the movement of the second shift arm (68), respectively. The variable valve operating apparatus for an internal combustion engine according to claim 6, characterized in that:   The operation positions for releasing the connection between the intake side rocker arms (32, 33) and the exhaust side rocker arms (34, 35), the intake side rocker arms (32, 33), and the exhaust side rocker arms (34, 35). The internal combustion engine according to claim 6 or 7, further comprising a shift holding mechanism (97) for elastically holding the operating position of the second shift arm (68) movable between operating positions for connecting the two. Variable valve gear.   The shift driving means (70) moves the rotating member (71) rotatably supported by the engine body (15A) along the arrangement direction of the rocker arms (32, 33; 34, 34). The variable valve operating apparatus for an internal combustion engine according to claim 4, further comprising a cam mechanism (72) adapted to convert the shift arm (67, 68, 69) into a movement.   The rotating member is an input pulley (71) around which a drive cable (73) is wound, and the input member (74) of the cam mechanism (72) is interposed between the input pulley (71) and the input member (74). The variable valve operating apparatus for an internal combustion engine according to claim 9, further comprising a lost motion mechanism (78).   10. The internal combustion engine according to claim 9, wherein a drive mechanism of a throttle valve is connected to the rotating member (71) so that the cam mechanism (72) is switched at a predetermined throttle opening. Variable valve device.   A governor mechanism (106) coupled to the camshaft (31) so as to generate axial thrust by rotation of the camshaft (31) is linked and coupled to the shift arm (67, 68, 69). 7. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the variable valve operating apparatus is an internal combustion engine.   The camshaft (31) is interposed between the cam chamber (21) and a cam holder (36, 37) provided on the cylinder head (19) so as to rotatably support the camshaft (31). In this way, the support plate (110) is fixed, and a pair of electromagnetic actuators (111, 112) are disposed on the support plate (110) to enable rotation between the first and second operating positions. The electromagnetic actuators (111, 112) are connected to a link (113) interlocked and connected to a shift arm (67, 68, 69) by rotating the link (113). The variable valve operating apparatus for an internal combustion engine according to claim 1 or 6.   A shift holding spring (119) for holding the first and second operating positions of the link (113) is provided between the link (113) and the support plate (110). The variable valve operating apparatus for an internal combustion engine according to claim 13.

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