JP2011111986A - Variable valve gear of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent impact-contact of a cam abutment part with a first cam in proximal movement of a second cam to a first cam side and thereby to suppress generation of hitting sound, in a variable valve gear of an engine in which the cam abutment part abutting on first and second cams is provided at a cam follower interlocked and connected with an engine valve biased by a spring in a valve closing direction. <P>SOLUTION: The first cam 31 is fixed to the camshaft 32, and the second cam 33 is supported by the camshaft 32 to allow axial movement of the second cam 33 between an operation position and a non-operation position, and not to allow relative rotation of the second cam 33 around an axis. In the operating position, the second cam 33 can abut on the cam abutment part 56 and gets closer to the first cam 31, and in the non-operating position, the second cam 33 cannot abut on the cam abutment part 56 and gets away from the first cam 31. An inclination face 71A inclined to get inward along a radial direction of the camshaft 32 as getting closer to the first cam 31 side is formed on a side face on a first cam 31 side of a second cam crest part 33b. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  According to the present invention, a cam follower that is linked and connected to an engine valve that is spring-biased by a valve spring in a valve closing direction and that is provided with a cam contact portion is disposed at a fixed position along the axis of the camshaft. A first cam having a base circle portion and a first cam peak portion projecting outward from the first base circle portion is fixed to the camshaft so as to be able to contact the cam contact portion, and a second base circle And a second cam having a second cam crest that protrudes outward from the second base circle so as to be located outward of the outer peripheral surface of the first cam as viewed from the axial direction of the camshaft, Axial movement between an operating position close to the first cam that enables contact with the cam contact portion and a non-operating position that makes contact with the cam contact portion impossible and away from the first cam Relative to the axis Is supported on the camshaft rolling as non relates variable valve device for an engine driving means is connected to a second cam that exerts a driving force along the axial direction of the camshaft.

  A cam follower is linked and connected to the engine valve spring-biased in the valve closing direction, and the first cam is fixed to the camshaft at a position corresponding to the cam contact portion in the axial direction of the camshaft. A separate second cam is provided on the camshaft so as not to rotate relative to the camshaft, while allowing the second cam to move between a position where the cam comes into contact with the cam contact portion and a position where contact with the cam contact portion is avoided. A variable valve operating apparatus for an engine that can be used is known from Patent Document 1.

JP 2009-185639 A

  However, in the device disclosed in Patent Document 1, the cam contact portion is in the middle of moving the second cam to contact the cam contact portion of the cam follower. When the second cam is brought into contact with the second cam, an axial driving force is applied to the second cam so as to oppose the force acting on the second cam from the cam contact portion toward the side separating the second cam from the first cam. When there is not, there is a possibility that the cam abutting part falls at the step between the second cam and the first cam, and the cam abutting part impacts the first cam, and a hitting sound may occur. Wear may occur at the corner of the second cam on the first cam side.

  The present invention has been made in view of such circumstances, and prevents the cam contact portion from impactingly contacting the first cam when the second cam is moved close to the first cam side. An object of the present invention is to provide a variable valve operating apparatus for an engine that can suppress generation of sound and suppress wear on a second cam side.

  In order to achieve the above object, the present invention provides a cam follower that is interlocked and connected to an engine valve that is spring-biased by a valve spring in the valve closing direction and that is provided with a cam contact portion. The first cam having a first base circle portion and a first cam peak portion protruding outward from the first base circle portion can be brought into contact with the cam contact portion. And a second cam crest that protrudes outward from the second base circle so as to be positioned outward from the outer peripheral surface of the first cam as viewed from the axial direction of the second base circle and the camshaft. A second cam having a portion that enables contact with the cam contact portion and is close to the first cam; and a non-operation position that makes contact with the cam contact portion impossible and moves away from the first cam. Enables axial movement between In addition, in the variable valve operating system for an engine, the second cam is supported by the camshaft, which is supported by the camshaft so that the relative rotation around the axis is impossible, and the driving means is connected to the second cam along the axial direction of the camshaft. A first feature is that an inclined surface is formed on the side surface of the mountain portion on the first cam side so as to be an inward position along the radial direction of the cam shaft toward the first cam side.

  According to the present invention, in addition to the configuration of the first feature, the driving means is directed to an actuator that exerts a pressing force that pushes the second cam toward the first cam, and a side opposite to the pressing force by the actuator. An urging member that urges the second cam, and when the cam abutting portion comes into contact with the inclined surface while the second cam is moving close to the first cam, the valve spring The sum of the axial component force of the spring force acting on the second cam via the engine valve and the cam contact portion of the cam follower and the biasing force by the biasing member is smaller than the pressing force exerted by the actuator. The second feature is that the inclination angle of the inclined surface is set as described above.

  In addition to the configuration of the second feature, the present invention has a third feature that an angle formed by the axis of the camshaft and the inclined surface is set to 15 degrees to 25 degrees.

  In the present invention, in addition to any one of the first to third features, the first base circle portion and the second base circle portion may be along arcs having the same radius centered on the axis of the camshaft. The fourth feature is that it is formed.

  According to the present invention, in addition to the configuration of the fourth feature, the edge of the inclined surface on the first cam side is more radially inward of the camshaft than the portion of the outer periphery of the first cam corresponding to the inclined surface. It is a fourth feature that it is arranged in the opposite position.

  According to the present invention, in addition to the configuration of the fifth feature, the inclined surface has a point on the axis of the camshaft as the apex and is located radially inward from the outer peripheral surface of the second base circle portion. A sixth feature is that it is formed over the entire circumference of the second cam so as to be along a virtual conical surface intersecting the first cam side end surface.

  According to the present invention, in addition to any of the first to sixth features, the cam contact portion is a roller that is pivotally supported by the cam follower, and at least a second cam side end outer peripheral edge of the roller Further, a seventh feature is that a chamfered portion that is inclined corresponding to the inclined surface is formed.

  Furthermore, in addition to any of the first to seventh features, the present invention provides an exhaust for opening the exhaust valve in the exhaust stroke of the engine, wherein the engine valve is an exhaust valve. An eighth feature is that the second cam is an exhaust gas recirculation cam for temporarily opening the exhaust valve during a compression stroke of the engine.

  The exhaust valve 25 of the embodiment corresponds to the engine valve of the present invention, the exhaust side first cam 31 of the embodiment corresponds to the first cam of the present invention, and the exhaust side second cam 33 of the embodiment Corresponding to the second cam of the present invention, the exhaust side rocker arm 39 of the embodiment corresponds to the cam follower of the present invention, the roller 56 of the embodiment corresponds to the cam contact portion of the present invention, and the coil of the embodiment The spring 62 corresponds to the biasing member of the present invention, and the solenoid 64 of the embodiment corresponds to the actuator of the present invention.

  According to the first feature of the present invention, an inward position along the radial direction of the camshaft toward the first cam side on the side surface on the first cam side of the second cam crest provided on the second cam; Since the inclined surface is formed in such a manner that the cam abutting portion abuts on the second cam peak portion while the second cam is moved to abut on the cam abutting portion of the cam follower, Even if the second cam moves to the side away from the first cam due to the force acting on the second cam from the contact portion, the cam contact portion simply slides to contact the first cam while contacting the inclined surface. Therefore, it is possible to prevent the cam contact portion from impacting the first cam due to the fall of the cam contact portion, to suppress the generation of hitting sound, and to suppress the occurrence of wear of the second cam. Can do.

  According to the second feature of the present invention, the second cam is separated from the first cam even if the cam contact portion contacts the inclined surface while the second cam is moving close to the first cam. It is possible to prevent the occurrence of a hitting sound by preventing the contact portion of the cam contact portion from moving from the inclined surface to the first cam side.

  According to the third feature of the present invention, by setting the angle formed by the axis of the camshaft and the inclined surface to 15 degrees to 25 degrees, while preventing the axial width of the second cam from expanding as much as possible, Generation of a hitting sound can be prevented.

  According to the fourth feature of the present invention, the first and second base circle portions are formed so as to be along arcs having the same radius centered on the axis of the camshaft. No hitting sound is generated when the second cam moves in the axial direction in contact with any one of the second base circles.

  According to the fifth feature of the present invention, the edge on the first cam side of the inclined surface is located at the radially inner position of the camshaft than the portion corresponding to the inclined surface of the outer periphery of the first cam. When the second cam is moved from the operating position to the non-operating position while the cam contact portion is in contact with the inclined surface, the cam contact portion does not fall with a step from the inclined surface to the first cam side. Can be.

  According to the sixth aspect of the present invention, one point on the axis of the camshaft is a vertex and intersects the first cam side end surface of the second cam radially inward from the outer peripheral surface of the second base circle. Since the inclined surface is formed along the virtual conical surface, the edge of the inclined surface on the first cam side of the inclined surface is formed from the first base circular portion while forming the first and second base circular portions in an arc shape having the same radius. Further, the structure at the radially inner position of the camshaft can be realized in such a manner that no step is generated between the inclined surface and the second base circle.

  According to the seventh feature of the present invention, a chamfered portion that is inclined corresponding to the inclined surface of the second cam is formed at least on the outer peripheral edge of the second cam side end of the roller that is the cam contact portion. The roller does not make point contact with the second cam, and the contact surface pressure of the roller to the second cam can be reduced to suppress wear of the second cam peak.

  Further, according to the eighth feature of the present invention, in the state in which the first cam is an exhaust cam and the second cam is an exhaust gas recirculation cam, the second cam is in contact with the cam contact portion. As a result, combustion of the air-fuel mixture in the combustion chamber can be activated to reduce NOx emissions, improve engine output, reduce fuel consumption, and the like.

1 is a side view of a motorcycle. It is a principal part longitudinal cross-sectional view of the engine seen from the same direction as FIG. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. FIG. 4 is an enlarged view of a portion indicated by an arrow 4 in FIG. 3. It is a figure which shows the valve opening lift characteristic of an intake valve and an exhaust valve. FIG. 6 is a sectional view taken along line 6-6 of FIG. FIG. 7 is a view taken in the direction of arrow 7 in FIG. 2. FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 7. FIG. 9 is a cross-sectional view taken along line 9-9 in FIG. 4. It is a perspective view of an exhaust side second cam. It is sectional drawing which expands and shows a part of exhaust side 1st and 2nd cam. 6 is a perspective view of an exhaust-side second cam according to Embodiment 2. 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 11. First, in FIG. 1, an engine E and a fuel tank T are mounted on a body frame F of the motorcycle. The front wheel Wf is supported through the front fork 1 to which the steering handle 2 is connected to the upper part, and the swing arm SA that supports the rear wheel Wr is swingable up and down at a substantially central portion of the vehicle body frame F. A rear cushion R is provided between the swing arm SA and the vehicle body frame F. The driving force of the engine E is transmitted to the rear wheel Wr via the chain transmission mechanism 4.

  The vehicle body frame F includes a head pipe H that supports the front fork 1 so as to be steerable, a down tube DT that extends downward from the head pipe H and passes through the front of the engine E, and a rear lower part of the head pipe H. A main frame MF that extends and extends downward through the upper and rear sides of the engine E, a seat tube ST that has a front end fixed to an intermediate portion of the main frame MF and extends rearward, and an intermediate portion and a main frame of the seat tube ST And a back tube BT connecting the rear portions of the MF. An engine E is supported between a rear portion of the main frame MF and a lower portion of the down tube DT, and a tandem seat S is supported on the seat tube ST.

  2 and 3, the engine body 10 of the engine E is configured by coupling a crankcase 11, a cylinder block 12, a cylinder head 13 and a head cover 14, and the cylinder block 12 can freely slide a piston 15. A cylinder head 13 having a cylinder bore 16 fitted to the cylinder block 11 and coupled to the crankcase 11 and forming a combustion chamber 17 facing the top of the piston 15 with the cylinder block 12 is coupled to the cylinder block 12. A head cover 14 is coupled to the cylinder head 13 from the side opposite to the cylinder block 12. Moreover, a gasket 9 made of an elastic material is interposed between the cylinder head 13 and the head cover 14.

  The cylinder head 13 is provided with an intake port 18 opened on one side surface thereof and an exhaust port 19 opened on the other side surface of the cylinder head 13, and an intake pipe 21 forming an intake passage 20 communicating with the intake port 18. Is connected to the cylinder head 13, and a fuel injection valve 22 is attached to the intake pipe 21.

  The cylinder head 13 has an intake valve 24 for switching communication / blocking between the intake port 18 and the combustion chamber 17 and an exhaust valve 25 for switching communication / blocking between the exhaust port 19 and the combustion chamber 17. The intake valve 24 and the exhaust valve 25 are urged in the valve closing direction by the valve springs 26 and 27. Further, a spark plug 23 is attached to the cylinder head 13 so that the tip of the cylinder head 13 faces the combustion chamber 17.

  Referring also to FIG. 4, the intake valve 24 and the exhaust valve 25 are driven to open and close by a valve mechanism 29 housed in a valve chamber 28 formed between the cylinder head 13 and the head cover 14. The valve mechanism 29 is disposed between the intake valve 24 and the exhaust valve 25, and is provided with a camshaft 32 provided with an intake cam 30 and an exhaust side first cam 31, and an exhaust side first cam 31. The cylinder head 14 has different cam profiles and has an exhaust-side second cam 33 mounted on the outer periphery of the camshaft 32 so as to be movable in the axial direction and relatively non-rotatable, and an axis parallel to the camshaft 32. The intake side and exhaust side rocker shafts 36 and 37 are supported by the intake side, and the intake cam 24 is driven to open and close by following the intake cam 30. An exhaust-side rocker shaft 37 is driven to open and close the exhaust valve 25 by being driven by the intake-side rocker arm 38 that is swingably supported by the foot 36 and the exhaust-side first cam 31 or the exhaust-side second cam 33. And an exhaust-side rocker arm 39 supported in a swingable manner by the cylinder head 13.

  The cylinder head 13 is integrally provided with a first support portion 42 having a first bearing hole 40 and a second support portion 43 having a second bearing hole 41 coaxial with the first bearing hole 40. One end portion of the camshaft 32 is rotatably supported by the first support portion 42 with a first ball bearing 44 interposed between the inner periphery of the first bearing hole 40, and is located near the other end of the camshaft 32. The portion penetrates the second bearing hole 41 in a freely rotatable manner, and a second ball bearing 45 is interposed between the inner periphery of the second bearing hole 41 and the camshaft 32. Thus, the camshaft 32 is press-fitted into the inner rings of the first and second ball bearings 44 and 45, and the intake cam 30 and the exhaust side first cam 31 have the intake cam 30 disposed on the first ball bearing 44 side. In addition, the exhaust side first cam 31 is formed integrally with the camshaft 32 between the first and second ball bearings 44 and 45 so that the exhaust side first cam 31 is disposed on the second ball bearing 45 side. The exhaust-side first cam 31 is mounted on the camshaft 32 at a position sandwiching the exhaust-side first cam 31 with the intake cam 30.

  Rotational power from a crankshaft (not shown) is transmitted to the camshaft 32 via a timing transmission mechanism 47. The timing transmission mechanism 47 is transmitted from the second ball bearing 45 of the camshaft 32. An endless cam chain 50 is wound around a driven sprocket 48 fixed to the projecting end of the cylinder and a drive sprocket (not shown) fixed to the crankshaft. It is stored in a chain travel passage 51 formed over the block 12, the cylinder head 13 and the head cover 14 so as to travel.

  Referring to FIG. 2, the intake cam 30 includes an arcuate base circle 30a centered on the axis of the camshaft 32, and a base circle that protrudes outward from the base circle 30a. A cam crest 30b connecting both circumferential ends of the cam 30a. The exhaust-side first cam 31 includes an arc-shaped first base circle 31a centering on the axis of the cam shaft 32, and a first base. A first cam crest portion 31b connecting both circumferential ends of the first base circle portion 31a so as to protrude outward from the circle portion 31a, and the intake cam 30 and the exhaust side first cam 31 are The cam crest 30b and the first cam crest 31b are fixed to the camshaft 32 so that the phases of the cam crest 30b and the first cam crest 31b are shifted from each other.

  A roller 52 that is in rolling contact with the intake cam 30 is pivotally supported at one end portion of the intake side rocker arm 38 that is swingably supported by the intake side rocker shaft 36, and an intake valve is provided at the other end portion of the intake side rocker arm 36. A tappet screw 53 abutting on the stem end 24a of 24 is screwed together so that the advance / retreat position can be adjusted.

  At one end of the exhaust side rocker arm 39 that is swingably used by the exhaust side rocker shaft 37, a roller 56 as a cam contact portion rolls on the exhaust side first cam 31 and the exhaust side second cam 33. A tappet screw 54 that is pivotally supported so as to be able to come into contact and is in contact with the stem end 25a of the exhaust valve 25 is screwed to the other end portion of the exhaust side rocker arm 39 so that the advance / retreat position can be adjusted. Thus, the exhaust side first cam 31 is fixed to the camshaft 32 at a position corresponding to the roller 56 of the exhaust side rocker arm 39 in a direction along the axis of the camshaft 32.

  The exhaust-side second cam 33 is close to the exhaust-side first cam 31 and comes into contact with the roller 56 of the exhaust-side rocker arm 39 (the position indicated by the solid line in FIGS. 3 and 4), and the exhaust-side second cam 33 The camshaft 32 moves in the axial direction between a non-operating position (a position indicated by a chain line in FIG. 4) away from the cam 31 and avoiding contact with the roller 56 of the exhaust side rocker arm 39. The camshaft 32 is fitted and supported on the outer periphery of the camshaft 32 while disabling relative rotation about the axis of the camshaft 32 while making it possible.

  The exhaust-side second cam 33 is an exhaust gas recirculation cam that opens and drives the exhaust valve 25 so that a part of the exhaust gas discharged from the combustion chamber 17 is returned to the combustion chamber 17. An arc-shaped second base circle portion 33a centering on the axis, and a second base circle portion located on the outer side of the outer peripheral surface of the exhaust side first cam 31 when viewed from the axial direction of the camshaft 32. And a second base circle 33a of the exhaust side second cam 33 and a first base circle 31a of the exhaust side first cam 31 are formed on the camshaft. It is formed along an arc having the same radius centered on 32 axes.

  Referring also to FIG. 5, the second cam crest 33 b of the exhaust side second cam 33 is slightly away from the second base circle 33 a in a phase corresponding to the valve closing end of the cam crest 30 b in the intake cam 30. Both ends of the second cam crest 33b in the circumferential direction are connected to the second base circle 33a so as to draw a smooth curve. Thus, when the exhaust side second cam 33 moves to the operating position where it abuts on the roller 56 of the exhaust side rocker arm 39, the exhaust side rocker arm 39 is exhausted by the first cam crest 31b of the exhaust side first cam 31 by the exhaust valve 25. The valve closing state is maintained by abutting the first base circle 31a of the exhaust side first cam 31 after being rotated so as to open the valve, but the final stage when the intake valve 24 is closed Further, the exhaust-side rocker arm 39 is slightly rotated so that the exhaust valve 25 is slightly opened by the second cam peak portion 33 b of the exhaust-side second cam 33. As a result, the exhaust valve 25 can be temporarily opened during the compression stroke, and combustion of the air-fuel mixture in the combustion chamber 17 is activated by the exhaust gas, reducing NOx emissions, improving engine output, and improving fuel efficiency. Reduction and the like can be achieved.

  On the other hand, when the exhaust side second cam 33 moves to a non-operating position that avoids contact with the roller 56 of the exhaust side rocker arm 39, the exhaust side rocker arm 39 is driven to rotate only by the exhaust side first cam 31, and the exhaust valve 25 is opened and closed in an operating manner corresponding to the cam profile of the exhaust side first cam 31. In other words, the opening / closing operation mode of the exhaust valve 25 corresponding to the cam profile of the exhaust side first cam 31 and the timing when the valve is originally closed while opening / closing corresponding to the cam profile of the exhaust side first cam 31 are temporary. The operation mode of the exhaust valve 25 that is adapted to obtain the valve open state can be switched by the movement of the exhaust side second cam 33 along the axial direction of the cam shaft 32.

  The camshaft 32 has a coaxial center hole 57 and is formed hollow, and the driven sprocket 48 is provided with a center hole 48 a corresponding to the center hole 57. The camshaft 32 is coaxially screwed with a bolt 58 that closes the end of the center hole 57 on the opposite side of the driven sprocket 48.

  The exhaust side second cam 33 is connected to a drive means 55 that exerts a driving force along the axial direction of the camshaft 32. The drive means 55 connects the exhaust side second cam 33 to the exhaust side first cam. A solenoid 64 that is an actuator that exerts a pressing force to the 31st side, and a coil spring 62 that is a biasing member that biases the exhaust-side second cam 33 toward the side opposite to the pressing force by the solenoid 764. .

  In the central hole 57 of the camshaft 32, a rod 59 having a small diameter shaft portion 59a facing the bolt 58 at one end is coaxially inserted so as to be axially movable, and the other end of the rod 59 is It protrudes from the driven sprocket 48.

  Further, at the portion where the exhaust side second cam 33 is disposed, the camshaft 32 is connected to the inner peripheral surface of the center hole 57 and the outer peripheral surface of the camshaft 32 and extends in the axial direction of the camshaft 32. As shown in FIG. 6, the pair of guide holes 60, 60 is provided in the camshaft 32 with an axis orthogonal to the axis C of the center hole 57, and moves axially on the outer periphery of the camshaft 32. The exhaust-side second cam 33 and the rod 59, which are mounted so as to be capable of sliding, slide through the guide holes 60 in the direction along the axis C while passing through the guide holes 60. Connected with

  A coil spring 62 surrounding the small-diameter shaft portion 59a of the rod 59 is contracted between the rod 59 and the bolt 58, and the rod 59 is on the side where the exhaust side second cam 33 is in the non-operating position. Is biased by the return spring 62.

  7 and 8, the crankcase 11, the cylinder block 12 and the cylinder head 13 are fastened by a plurality of, for example, four through bolts 68, 68... Screwed into the crankcase 11. The head cover 14 is fastened to the cylinder head 13 with a plurality of bolts 90, 90, for example, with two bolts 90, 90 interposed between the cylinder head 13 and a gasket 9 made of an elastic material. Are provided with elastic members 89.

  A rotating lever 67 is connected to the other end of the rod 59 protruding from the driven sprocket 48, and the rotating lever 67 is supported by the cylinder head 13 and the head cover 14. 66 is rotatably supported.

  The cylinder head 13 is integrally provided with a shaft support portion 92 having a bottomed press-fitting hole 91 into which one end portion of the support shaft 66 is press-fitted, and the head cover 14 is provided with the other end portion of the support shaft 66. A shaft support portion 94 having a support hole 93 for fitting and supporting is provided corresponding to the shaft support portion 92 on the cylinder head 13 side.

  The rotating lever 67 has a pair of substrate portions 67a, 67b that slide through the support shaft 66 and slidably contact the shaft support portions 92, 94 of the cylinder head 13 and the head cover 14, respectively, and the substrate portions 67a, 67b. A connecting plate portion 67c that connects the connecting plate portion 67c, an arm portion 67d that extends from a portion of the connecting plate portion 67c closer to the cylinder head 13 toward the rod 59 side and abuts against the rod 59, and the connecting plate An actuator connecting arm portion 67e extending from the portion of the portion 67c near the head cover 14 to the opposite side of the cylinder head 13 is integrally provided.

  Incidentally, an opening 95 is provided in the head cover 14 corresponding to the cam chain passage 51 provided in the engine body 10 excluding the head cover 14, and the actuator connecting portion 67 e of the rotating lever 67 is provided in the opening 95. And protrudes outward from the valve operating chamber 28.

  On the other hand, a protruding portion 14a protruding outward is integrally formed on the outer surface of the head cover 14 at a portion corresponding to the opening 95, and the opening 95 is provided in the middle portion of the protruding portion 14a. A circular hole 96 is formed so as to have an axis perpendicular to a plane parallel to the axes of the support shaft 66, the camshaft 32, and the rod 59.

  A lid member 97 that airtightly closes one end of the circular hole 96 is screwed to the protrusion 14a, and a mounting plate 98 of the solenoid 64 closes the other end of the circular hole 96 in an airtight manner. Fastened by a pair of bolts 99, 99. Thus, as shown in FIG. 8, the solenoid 64 is configured so that the entire solenoid 64 overlaps the head cover 14 when viewed from the direction along the coupling direction 69 of the cylinder head 13 and the head cover 14, that is, the head cover 14. The solenoid 64 is attached to the protrusion 14a of the head cover 14 so that the solenoid 64 does not protrude outward. In addition, the head cover 14 is integrally provided with a fastened portion 14b projecting laterally in the vicinity of the protrusion 14a, and the fastened portion 14b is fastened to the cylinder head 13 by a bolt 100. Further, an elastic member (not shown) similar to the elastic members 89 interposed between the bolts 90 and the head cover 14 is interposed between the fastened portions 14b. That is, the head cover 14 is fastened to the cylinder head 13 by the two bolts 90... And the bolt 100 inserted through the fastened portion 14 b disposed in the vicinity of the solenoid 64.

  The protrusion 14 a of the head cover 14 and the lid member 97 and the mounting plate 98 fixed to the protrusion 14 a so as to close both ends of the circular hole 66 provided in the protrusion 14 a are arranged via the opening 95. Thus, a control chamber 101 communicating with the valve operating chamber 28 is formed.

  The solenoid 64 has an output shaft 65 that is perpendicular to the axis of the rod 59 and parallel to a plane passing through the axis of the support shaft 66 and is movable in the axial direction. The actuator is inserted into the adjustment chamber 101, and the tip of the actuator connecting portion 67 e of the rotation lever 67 is connected to the output shaft 65 in the adjustment chamber 101.

  In addition, an adjustment mechanism 102 that adjusts the amount of rotation of the rotation lever 67 that accompanies the operation of the solenoid 64 is provided at the distal end of the actuator connecting portion 67 e so as to be accommodated in the adjustment chamber 101.

  The adjustment mechanism 102 includes a weld nut 103 that is fixed to the tip of the actuator connecting portion 67e, a tappet screw 104 that is screwed into the weld nut 103 and passes through the actuator connecting portion 67e, and a screw that is screwed into the tappet screw 104. The stopper nut 105 is in contact with and engaged with the weld nut 103, and the tappet screw 104 contacts the tip of the output shaft 65. Thus, by loosening the locking nut 105, the axial advance / retreat position of the tappet screw 104 can be adjusted, whereby the rotation amount of the rotation lever 67 in accordance with the operation of the solenoid 64, that is, the movement amount of the rod 59. Will be adjusted.

  Thus, when the solenoid 64 is energized by energization, the protruding amount of the output shaft 65 increases, whereby the rotating lever 67 rotates, and the rod 59 resists the spring force of the coil spring 62 in the axial direction. When the exhaust side second cam 33 is moved to the operating position close to the exhaust side first cam 31 and the solenoid 64 is deenergized, the rod 59 is moved in the axial direction by the spring force of the coil spring 62. By moving, the exhaust side second cam 33 moves to a non-operating position away from the exhaust side first cam 31.

  Referring to FIGS. 9 and 10 together, the side surface of the exhaust side second cam 33 on the side of the exhaust side first cam 31 of the second cam crest 33b is directed toward the exhaust side first cam 31 side. An inclined surface 71A that is inclined so as to be an inward position along the radial direction of 32 is formed. In FIG. 9 and FIG. 10, the inclined surface 71A is shown by hatching in order to clarify that it is the inclined surface 71A, but this does not show a cross section.

  In addition, while the exhaust side second cam 33 is moving close to the exhaust side first cam 31 so as to move from the non-operating position to the operating position, the roller 56 of the exhaust side rocker arm 39 is inclined as shown in FIG. When contacted with the surface 71A, the axial component F1 of the spring force acting on the exhaust side second cam 33 from the valve spring 27 through the exhaust valve 25 and the roller 56 of the exhaust side rocker arm 39 (see FIG. 4). And the spring force F2 (see FIG. 4) by the coil spring 62 acts on the exhaust side second cam 33 toward the non-actuated position side, and the pressing force exerted by the solenoid 64 moves toward the actuated position side. 2 acts on the cam 33. The inclination angle of the inclined surface 71A is set so that the sum of the axial component force F1 and the spring force F2 is smaller than the pressing force by the solenoid 63. The axis of the cam shaft 32, the angle of the inclined surface 71A forms α is 5 to 45 degrees, desirably set to 15 to 25 degrees.

  Here, if the angle α is reduced, it is desirable that the axial component force acting on the exhaust-side second cam 33 is reduced by the roller 56 coming into contact with the inclined surface 71A. Since the width of the exhaust-side second cam 33 along the axial direction of the shaft 32 becomes too large, the angle α is set to 5 degrees or more, preferably 15 degrees or more. Further, when the angle α is increased, the axial force acting on the exhaust-side second cam 33 is increased by the roller 56 coming into contact with the inclined surface 71A. Therefore, the angle α is preferably 45 degrees or less. Is set to 25 degrees or less.

  Moreover, the end edge 71Aa of the inclined surface 71A on the exhaust side first cam 31 side is disposed at a radially inner position of the camshaft 32 than the portion corresponding to the inclined surface 71A on the outer periphery of the exhaust side first cam 31. The first cam 31 side of the exhaust side second cam 33 has a point on the axis of the camshaft 32 as a vertex and is radially inward of the outer peripheral surface of the second base circle 33a. The inclined surface 71 </ b> A is formed over the entire circumference of the exhaust-side second cam 33 so as to follow the virtual conical surface 72 that intersects the end surface.

  Further, at least the outer peripheral edge of the end on the exhaust side second cam 33 side of the roller 56 pivotally supported by the exhaust side rocker arm 39, in this embodiment, the outer peripheral edge of both ends in the axial direction of the roller 56 corresponds to the inclined surface 71A. Inclined chamfered portions 56a and 56a are formed.

  Next, the operation of the first embodiment will be described. The exhaust side first cam 31 is an exhaust cam for opening the exhaust valve 25 in the exhaust stroke of the engine E, and the exhaust side second cam 33 is the engine E. Since the exhaust gas recirculation cam is used to temporarily open the exhaust valve 25 during the compression stroke, the exhaust gas in the combustion chamber 17 is mixed with exhaust gas when the exhaust side second cam 33 is in contact with the roller 56. Can be activated to reduce NOx emissions, improve engine output, reduce fuel consumption, and the like.

  Moreover, an inward position along the radial direction of the camshaft 32 toward the exhaust side first cam 31 side on the side surface on the exhaust side first cam 31 side of the second cam crest 33b provided on the exhaust side second cam 33. Since the inclined surface 71A is inclined so as to be in contact with the roller 56 of the exhaust side rocker arm 39, the roller 56 is moving the second cam peak portion 33b while the exhaust side second cam 33 is being moved. Even if the exhaust-side second cam 33 is moved away from the exhaust-side first cam 31 by the force acting on the exhaust-side second cam 33 from the roller 56, the roller 56 contacts the inclined surface 71A. Since it only slides in contact with the exhaust side first cam 31 while being in contact with the exhaust side, the roller 56 does not come into impact contact with the exhaust side first cam 31 due to the fall of the roller 56, thereby suppressing the occurrence of sound. It becomes possible to suppress the wear of the exhaust-side second cam 33.

  The driving means 55 also has a solenoid 64 that exerts a pressing force to push the exhaust side second cam 33 toward the exhaust side first cam 31 and the exhaust side second cam 33 toward the side opposite to the pressing force by the solenoid 64. A coil spring 62 that can be attached, and when the roller 56 abuts against the inclined surface 71A while the exhaust-side second cam 33 is moving close to the exhaust-side first cam 31, the valve spring The solenoid 64 exhibits the sum of the axial component of the spring force acting on the exhaust side second cam 33 from the exhaust valve 25 and the roller 56 of the exhaust side rocker arm 39 and the biasing force of the coil spring 62 from 27. Since the inclination angle of the inclined surface 71A is set to be smaller than the pressing force, the roller 56 contacts the inclined surface 71A while the exhaust side second cam 33 is moving close to the exhaust side first cam 31. Even so, the exhaust side second cam 33 is prevented from returning to the side away from the exhaust side first cam 31, and the contact portion of the roller 56 moves from the inclined surface 71A to the exhaust side first cam 31 side. It is possible to prevent the occurrence of hitting sound.

  Further, by setting the angle α formed by the axis of the camshaft 32 and the inclined surface 71A to 15 degrees to 25 degrees, the generation of hitting sound is prevented while preventing the axial width of the exhaust-side second cam 33 from being expanded as much as possible. Can be prevented.

  Further, the first base circle portion 31 of the exhaust side first cam 31 and the second base circle portion 33a of the exhaust side second cam 33 are formed along an arc having the same radius with the axis of the cam shaft 32 as the center. Therefore, no sound is generated when the exhaust-side second cam 33 moves in the axial direction in a state where the roller 56 is in contact with either the first or second base circle 31a or 33a.

  Moreover, since the edge 71Aa on the exhaust side first cam 31 side of the inclined surface 71A is located at the radially inner position of the camshaft 32 than the portion corresponding to the inclined surface 71A on the outer periphery of the exhaust side first cam 31. When the exhaust side second cam 33 is moved from the operating position to the non-operating position while the roller 56 is in contact with the inclined surface 71A, the roller 56 falls from the inclined surface 71A to the exhaust side first cam 31 side with a step. You can avoid that.

  An imaginary cone having a point on the axis of the camshaft 32 as a vertex and intersecting the exhaust-side first cam 31 side end surface of the exhaust-side second cam 33 radially inward from the outer peripheral surface of the second base circle 33a. Since the inclined surface 71A is formed along the surface 72, the edge of the inclined surface 71A on the exhaust side first cam 31 side while forming the first and second base circular portions 31a and 33a in an arc shape with the same radius. A structure in which 71Aa is located radially inward of the camshaft 32 relative to the first base circle portion 31a can be realized without causing a step between the inclined surface 71A and the second base circle portion 33a. .

  Further, a chamfered portion 56a that is inclined corresponding to the inclined surface 71A of the exhaust side second cam 33 is formed at least on the outer peripheral edge of the end portion of the roller 56 on the exhaust side second cam 33 side. Point contact with the cam 33 does not occur, and the contact surface pressure of the roller 56 to the exhaust-side second cam 33 can be reduced to suppress wear of the second cam peak portion 33b.

  A second embodiment of the present invention will be described with reference to FIG. 12, but the portions corresponding to the first embodiment are only shown with the same reference numerals, and detailed description thereof is omitted.

  On the side surface of the exhaust side second cam 33 on the exhaust side first cam 31 (see Example 1) side, the inner side of the cam shaft 32 (see Example 1) extends in the radial direction toward the exhaust side first cam 31 side. An inclined surface 71B that is inclined so as to be in the opposite position is formed. The inclined surface 71B is formed so as to have the same width over the entire circumference of the exhaust side second cam 33 with reference to the outer peripheral surface of the exhaust side second cam 33, and the axis of the camshaft 32; The angle α formed by the inclined surface 71B is set to 5 to 45 degrees, preferably 15 to 25 degrees.

  Also in the second embodiment, the roller 56 (see the first embodiment) does not come into impact contact with the exhaust-side first cam 31 due to the drop of the roller 56, and it is possible to suppress the occurrence of hitting sound. Become.

  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, although the case where the engine valve is the exhaust valve 25 has been described in the above embodiment, the present invention can be applied to the case where the engine valve is the intake valve 24.

25 ... Exhaust valve 27 as engine valve ... Valve spring 31 ... Exhaust side first cam 31a as first cam ... First base circle 31b ... First cam crest 32 .... Exhaust side second cam 33a that is the second cam ... Second base circle 33b ... Second cam crest 39 ... Exhaust side rocker arm 55 that is the cam follower Driving means 56... Roller 56 a as a cam contact portion... Chamfered portion 62... Coil spring 64 as an urging member... Solenoids 71 A and 71 B as actuators. Virtual conical surface E ... Engine

Claims (8)

  A cam follower (39) that is linked and connected to the engine valve (25) that is spring-biased in the valve closing direction by the valve spring (27) and that is provided with a cam contact portion (56) is an axis of the camshaft (32). The first cam (31) is disposed at a fixed position along the first base circle (31a) and has a first cam peak (31b) protruding outward from the first base circle (31a). It is fixed to the camshaft (32) so as to be able to come into contact with the cam contact portion (56), and the first cam (see from the axial direction of the second base circle portion (33a) and the camshaft (32)). 31) a second cam (33) having a second cam peak portion (33b) projecting outward from the second base circular portion (33a) so as to be located on the outer side of the outer peripheral surface of 31). First contact with the contact portion (56) is possible. The axial movement between the operating position close to the cam (31) and the non-operating position moving away from the first cam (31) by disabling contact with the cam contact portion (56) is possible. A driving means (55) which is supported on the camshaft (32) and disables relative rotation around the axis and which exerts a driving force along the axial direction of the camshaft (32) is connected to the second cam (33). In the variable valve operating apparatus for an engine, the inner side of the second cam peak portion (33b) on the side of the first cam (31) side along the radial direction of the camshaft (32) toward the first cam (31) side. A variable valve operating system for an engine, characterized in that inclined surfaces (71A, 71B) inclined so as to be in a lateral position are formed.   The drive means (55) has an actuator (64) that exerts a pressing force that pushes the second cam (33) toward the first cam (31), and faces away from the pressing force by the actuator (64). A biasing member (62) for biasing the second cam (33), and the cam contact portion (56) is in the middle of the second cam (33) moving close to the first cam (31). When contacting the inclined surfaces (71A, 71B), the second cam (33) from the valve spring (27) through the engine valve (25) and the cam contact portion (56) of the cam follower (39). The inclined surfaces (71A, 71B) so that the sum of the axial component force of the spring force acting on the urging force and the urging force by the urging member (62) is smaller than the pressing force exerted by the actuator (64). An inclination angle is set. 1 variable valve device for an engine according.   The variable valve gear for an engine according to claim 1 or 2, wherein an angle formed by an axis of the camshaft (32) and the inclined surface (71A, 71B) is set to 15 degrees to 25 degrees. .   The first base circle portion (31a) and the second base circle portion (33a) are formed so as to follow an arc having the same radius centered on the axis of the camshaft (32). The variable valve operating apparatus of the engine in any one of -3.   The edge of the inclined surfaces (71A, 71B) on the first cam (31) side is more than the portion corresponding to the inclined surfaces (71A, 71B) in the outer periphery of the first cam (31). 5) The variable valve operating apparatus for an engine according to claim 4, wherein the variable valve operating apparatus is disposed at a radially inward position.   The inclined surface (71A) has a point on the axis of the camshaft (32) as an apex, and the second cam (33) is located radially inward from the outer peripheral surface of the second base circle (33a). The variable valve for an engine according to claim 5, characterized in that it is formed over the entire circumference of the second cam (33) along a virtual conical surface (72) intersecting with the end face on the one cam (31) side. apparatus.   The cam abutting portion is a roller (56) pivotally supported by the cam follower (39), and at least the second cam (33) side end outer peripheral edge of the roller (56), the inclined surface (71A, The variable valve operating apparatus for an engine according to any one of claims 1 to 6, wherein a chamfered portion (56a) inclined corresponding to 71B) is formed.   The engine valve is an exhaust valve (25), the first cam (31) is an exhaust cam for opening the exhaust valve (25) during the exhaust stroke of the engine (E), and the second cam (33 8) An exhaust gas recirculation cam for temporarily opening the exhaust valve (25) during the compression stroke of the engine (E). Variable valve gear.

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