JP2005090315A - Valve system and internal combustion engine equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of fretting corrosion in a tappet roller, in a valve system constituted for advancing and retreating a valve by rollingly contacting with a cam, with an outer peripheral surface of the tappet roller as a cross-sectional convex curved surface. <P>SOLUTION: This valve system is constituted so that a tappet guide 23 can be fixed by moving in the axial direction of a valve stem 31a, and is constituted so that the cam 13 and the tappet roller 21 become a noncontact state in an unlifting area in an almost all areas B in the axial direction of the cam 13, by adjusting a position of the tappet guide 23. Thus, a central part (in the vicinity of a contact angle of 0 degree) of the cross-sectional convex curved surface being an outer peripheral surface of the tappet roller 21, can be prevented from being beaten by micro-vibration in the unlifting area, and the occurrence of the fretting corrosion (micro-abrasion) can be prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a valve gear for motorcycles, automobiles, and the like and an internal combustion engine equipped with the same.

  In an internal combustion engine, recently, a combination of a variable phase and a cam switching has been started, and thereafter, a system using a three-dimensional cam in which an operating angle and a lift amount are continuously variable has been proposed. For example, there is a type in which a follow-up mechanism for a contact angle change is provided at the top of a direct hitting cylindrical tappet, and a valve lift is steplessly varied by sliding a three-dimensional cam in the axial direction.

  The three-dimensional cam has a cam portion that is inclined in the longitudinal direction (the axial direction of the camshaft) and is formed into a shape that continuously changes the valve lift. In this case, the cam operating angle and the lift timing are set to change simultaneously with the cam height so as to have a desired lift curve. By moving such a cam along the camshaft, the valve lift amount, operating angle, and lift timing can be variably controlled steplessly.

  By applying such a three-dimensional cam to the intake valve, the throttle valve for forming the air-fuel mixture can be eliminated and a so-called non-throttle valve engine can be realized. By eliminating the throttle valve, the intake pressure in the intake port averages the pulsation and becomes an atmospheric pressure or a negative pressure close thereto. Therefore, for example, the intake valve lift amount, opening timing, and time differ with respect to the engine speed. This is developed on the premise that a conventional engine has a throttle valve, and the amount of intake air into the cylinder is first adjusted with the throttle valve and then with the intake valve. Among them, there are some that slightly change the operation of the intake valve, but rotation control and output control are performed depending on the throttle valve restricting the intake passage, and if the throttle valve is lost, it cannot be controlled at all. In the present invention, since the conditions such as the intake pressure in the intake port are different, the dimensions and settings of each part are completely different. For the sake of convenience of explanation, even if they are described with the same name, their roles are completely different.

JP-A-4-187807

  In this type of valve operating apparatus, a configuration in which the outer peripheral surface of the tappet roller has a convex cross-sectional curved surface and is brought into contact with a cam to advance and retract the valve is considered. In this case, the central part (near contact angle 0 °) of the convex section of the cross-section, which is the outer peripheral surface of the tappet roller, does not hit during lift, but in the non-lift region, it is struck by minute vibrations because there is a gap corresponding to the tappet gap. Fretting corrosion (fine wear) may occur. The tappet is small in weight and small in amplitude, so it is a slight fretting corrosion. However, in an internal combustion engine that requires durability (for example, a four-wheeled engine that requires durability of 100,000 km or more). If no measures are taken, the sound will increase and the lift curve may be affected particularly in a region where the contact angle is small.

  The present invention has been made in view of the above points, and is a valve operating apparatus having a configuration in which the outer peripheral surface of a tappet roller has a convex cross-sectional surface and is brought into contact with a cam so as to advance and retract the valve. The object is to prevent the occurrence of ting corrosion.

The valve device of the present invention has a cam surface formed so that the cam height and the cam working angle continuously change, and is configured to rotate integrally with the camshaft and slide in the axial direction thereof. A tappet roller that causes the outer peripheral surface formed into a curved surface to come into rolling contact with the cam to advance and retract the valve via the valve stem, and a tappet guide that guides the tappet roller to move only in the axial direction of the valve stem. The tappet roller is restricted from moving from the predetermined position to the cam side, and the cam and the tappet roller are in a non-contact area in a predetermined area in the axial direction of the cam so that the cam and the tappet roller are not in contact with each other. Has characteristics.
Another feature of the valve operating apparatus according to the present invention is that the tappet guide restricts the tappet roller from moving from a predetermined position to the cam side, and the tappet guide is moved in the axial direction of the valve stem. It is in the point which made it the structure which can be moved and fixed to. In this case, for example, an urging unit that applies an urging force in the axial direction of the valve stem toward the cam side with respect to the tappet guide, and the tappet guide is restricted from moving toward the cam side. What is necessary is just to make it the structure which can move and fix the said tappet guide to the axial direction of the said valve stem by the control means which can change a position.
Another feature of the valve operating apparatus according to the present invention is that the restriction member provided on the tappet guide restricts the tappet roller from moving from a predetermined position to the cam side, and the restriction by the restriction member. The point is that the position can be adjusted and fixed. In this case, for example, the arm member is positioned above the arm member arranged so as to have a centering function in the tappet roller, and the arm member is restricted from moving from the predetermined position to the cam side. The restriction arm may be provided on the tappet guide. Further, one end of the restriction arm may be rotatably supported and the height position of the other end may be adjustable.
Another feature of the valve operating apparatus according to the present invention is that, in a predetermined region in the axial direction of the cam, a portion excluding the cam crest and the ramp portion is not processed, or only a centering process is performed. There is in point. Further, in the predetermined region in the axial direction of the cam, the diameter of the portion excluding the cam crest and the ramp portion is made smaller than the base circle. In addition, a partial region excluding the predetermined region in the axial direction of the cam is a base circle portion that makes the valve lift amount zero.

Another valve operating apparatus of the present invention has a cam surface formed so that the cam height and the cam working angle continuously change, and is configured to rotate integrally with the cam shaft and to be slidable in the axial direction thereof, A tappet roller whose outer peripheral surface having a convex curved surface is in rolling contact with the cam and advances and retracts the valve via a valve stem, and a biasing force against the tappet roller so that the tappet roller is always in contact with the cam And an urging means for imparting.
Another feature of the valve operating apparatus according to the present invention is that a spring is disposed between the cotter and the tappet shim in the valve retainer provided at the end of the valve stem, and the biasing force of the spring is set. Is provided to the tappet roller via the tappet shim.

  The internal combustion engine of the present invention is an internal combustion engine in which intake and exhaust are controlled by an intake valve and an exhaust valve, and is characterized in that the valve operating device of the present invention is provided.

  According to the present invention, since the tappet roller is restricted from moving from the predetermined position to the cam side, and the cam and the tappet roller are in non-contact in the non-lift region, the outer periphery of the tappet roller in the non-lift region. It is possible to prevent the central portion of the convex convex surface that is a surface from being struck by minute vibrations, and it is possible to prevent fretting corrosion from occurring at the central portion of the convex convex surface that is the outer peripheral surface of the tappet roller. .

  In addition, according to the present invention, the biasing means for applying a biasing force to the tappet roller so that the tappet roller is always in contact with the cam is provided. The center portion can be prevented from being hit by minute vibrations, and fretting corrosion can be prevented from occurring.

(First embodiment)
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The valve gear according to the present invention can be effectively applied to various gasoline engines mounted on a motorcycle or an automobile. In the present embodiment, for example, an engine of a motorcycle is taken as an example as shown in FIG.

  First, the overall configuration of the motorcycle 100 according to the present embodiment will be described. In FIG. 1, two front forks 103 supported by a steering head pipe 102 so as to be pivotable to the left and right are provided at a front portion of a vehicle body frame 101 made of steel or an aluminum alloy material. A handle bar 104 is fixed to the upper end of the front fork 103, and grips 105 are provided at both ends of the handle bar 104.

  A front wheel 106 is rotatably supported on the lower portion of the front fork 103, and a front fender 107 is fixed so as to cover the upper portion of the front wheel 106. The front wheel 106 has a brake disc 108 that rotates integrally with the front wheel 106.

  A swing arm 109 is swingably provided at a rear portion of the vehicle body frame 101, and a rear shock absorber 110 is mounted between the vehicle body frame 101 and the swing arm 109.

  A rear wheel 111 is rotatably supported at the rear end of the swing arm 109, and the rear wheel 111 is rotationally driven via a driven sprocket 113 around which a chain 112 is wound.

  The engine unit 1 mounted on the vehicle body frame 101 is supplied with an air-fuel mixture from an intake pipe 115 coupled to an air cleaner 114, and exhaust gas after combustion is exhausted through an exhaust pipe 116. The air cleaner 114 is installed in a large space behind the engine unit 1 and below the fuel tank 117 and the seat 118 to secure capacity. Therefore, the intake pipe 115 is coupled to the rear side of the engine unit 1, and the exhaust pipe 116 is coupled to the front side of the engine unit 1.

  A fuel tank 117 is mounted above the engine unit 1, and a seat 118 and a seat cowl 119 are connected to the rear of the fuel tank 117.

  Further, in FIG. 1, 120 is a headlamp, 121 is a meter unit including a speedometer, tachometer, or various indicator lamps, and 122 is a rearview mirror supported by the handlebar 104 via a stay 123. A main stand 124 is swingably attached to the lower part of the vehicle body frame 101 so that the rear wheel 111 can be grounded or floated from the ground.

  The vehicle body frame 101 extends obliquely downward and rearward from the head pipe 102 provided at the front portion, and is bent so as to wrap under the engine unit 1, and then forms a pivot 109 a that is a shaft support portion of the swing arm 109. It connects with the tank rail 101a and the seat rail 101b.

  The vehicle body frame 101 is provided with a radiator 125 in parallel with the vehicle body frame so as to avoid interference with the front fender 107, and a cooling water hose 126 is provided along the vehicle body frame 101 from the radiator 125, and an exhaust pipe 116. Communicates with the engine unit 1 without interference.

  2 is a cross-sectional view showing the main part of the valve gear in the first embodiment, FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2, and FIG. 4 is a cross-sectional view taken along the line BB in FIG. FIG. 5 is a sectional view taken along the line CC of FIG. A piston reciprocates up and down in a cylinder of an engine unit 1 that is an internal combustion engine, and a valve operating device is housed in a cylinder head 2 disposed at the upper part of the piston. The engine unit 1 described here is a single-cylinder engine, and has two valves on each of the intake side (IN) and the exhaust side (EX).

  The valve operating apparatus according to the first embodiment includes, on the intake side, a cam / camshaft unit 10, a tappet unit 20 disposed below the cam / camshaft unit 10, a valve unit 30 for controlling intake, and a valve And a valve deactivation unit 50 for deactivating one of the two intake valves 31 constituting the unit 30.

The exhaust side includes a cam / camshaft unit 10 _EX , a tappet unit 20 _EX disposed below the cam / camshaft unit 10 _EX , and a valve unit 30 _{EX for} exhaust control. Note that the valve deactivation unit is not included on the exhaust side.

Further, an accelerator shaft unit 40 that displaces the cams 13 and 13 _EX of the cam / camshaft units 10 and 10 _EX according to the accelerator opening is included. In this embodiment, the cam / camshaft unit 10 on the intake side and the exhaust side are included. The cam / camshaft unit 10 _EX is shared between the intake side and the exhaust side.

In the intake cam / camshaft unit 10, the camshaft 11 is rotatably supported via a bearing 12 as shown in FIGS. Drive sprocket end sprocket 15 is fixed to the cam shaft 11, the sprocket 15 of the intake side, also the sprocket 15 _EX for securing one end of the exhaust side camshaft 11 _EX, for fixing one end of a crank shaft (not shown) A cam chain is wound around between.

  A cam 13 is slidably mounted on the cam shaft 11 in the axial direction. In this example, a spline in which a ball 14 is interposed between the camshaft 11 and the cam 13 is formed, so that the relative rotation of the cam 13 and the camshaft 11 is restricted, and the cam 13 moves linearly (linear motion). It has become. Note that the camshaft 11 has a hollow structure, and the inside of the hollow serves as a lubricating oil passage, and can lubricate the spline portion and the like.

  Here, the cam 13 is configured as a “three-dimensional cam”, has a cam surface inclined in the longitudinal direction (the axial direction of the camshaft 11), and has a shape that continuously changes the valve lift amount. In this case, the cam operating angle and the lift timing change simultaneously with the cam height, that is, the cam operating angle increases as the valve lift amount increases, and the valve lift timing can also be changed.

  In the first embodiment, in most regions in the axial direction of the cam 13 (region B shown in FIG. 5), the diameter of the portion of the cam 13 excluding the cam crest and the ramp portion is made smaller than the base circle. In addition, the portion excluding the cam crest and the ramp portion is not processed (for example, when the cam 13 is a cast forged product, the cast forged surface is left), or only a centering process is performed. However, a partial region at the tip of the cam 13 in the axial direction (region A shown in FIG. 5) is a base circle portion that makes the valve lift amount zero, and finish processing is performed in the same manner as the cam crest and ramp portion. Yes.

Incidentally, the cam / camshaft unit 10 _EX the exhaust side, as shown in FIGS. 4 and 5, but the basic structure and the cam / cam shaft unit 10 on the intake side is the same, the specific specifications of the cam 13 _EX Is different from the cam 13.

  As shown in FIG. 3, the intake side tappet unit 20 includes a tappet roller 21 whose outer peripheral surface is a convex curved surface. In addition, the one side part which does not contact the cam 13 among the outer peripheral surfaces of the tappet roller 21 is made thin for the purpose of weight reduction.

  An arm member 22 is disposed in the tappet roller 21. The inner peripheral surface of the tappet roller 21 has a concave curved surface in section, and a ball 24 is interposed between the inner peripheral surface and the large diameter portion at the center of the arm member 22. Therefore, the tappet roller 21 is rotatably supported via the ball 24 and the arm member 22 is swingable. Even when the arm member 22 is tilted with respect to the tappet roller 21, the tappet roller 21 can be normally rotated. The centering function is demonstrated.

  Moreover, the tappet guide 23 is arrange | positioned so that the arm member 22 may be covered, and the both ends of the arm member 22 protrude from the both-ends opening. At both ends of the arm member 22, a pressing portion 22 a that comes into contact with a tappet shim 37 of the valve unit 30 described later is provided. The arm member 22 is hollow, and one end opening of the arm member 22 functions as an engaging portion with a tappet stopper 51 of a valve pause unit 50 described later. When the arm member 22 is not regulated by the tappet stopper 51, the arm member 22 moves up and down while being substantially parallel to the camshaft 11. However, when the arm member 22 is regulated by the tappet stopper 51, the engaging portion with the tappet stopper 51 is used as a fulcrum. Swing.

  A guide hole 23a is formed on the upper surface of the tappet guide 23, and a part of the tappet roller 21 protrudes toward the cam 13 from the guide hole 23a. The guide hole 23a is formed along the axial direction of the valve stem, so that the tappet roller 21 can move only in the axial direction of the valve stem 31a. When the tappet roller 21 rolls into contact with the cam 13 and is pressed, it functions as a valve lifter that moves the valve back and forth.

  Here, the tappet guide 23 is provided with attachment portions 23b, and the four corners of the tappet guide 23 are attached to the cylinder head 2 via these attachment portions 23b. Specifically, a rod-shaped guide / fixing bolt 25 is press-fitted to the cylinder head 2 side, and the guide / fixing bolt 25 is inserted into the holes formed in the attachment portion 23b of the tappet guide 23, respectively. Two nuts, a set nut 26 and a main nut 27, are fastened to the screw portion at the tip of the cum fixing bolt 25. In this case, a spring washer 28 is provided between the lower surface of the attachment portion 23 b of the tappet guide 23 and the flange portion 25 a formed on the guide and fixing bolt 25, and the valve stem 31 a toward the cam side with respect to the tappet guide 23 is provided. A biasing force in the axial direction is applied.

The exhaust-side tappet unit 20 _EX has the same basic configuration as the intake-side tappet unit 20 as shown in FIG.

  In the intake side valve unit 30, as shown in FIGS. 2 and 3, a valve stem 31 a includes two intake valves 31 guided by a valve guide 32. When the intake valve 31 is lifted, a mixture of air guided from the air cleaner 114 via the intake port 33 and fuel sprayed from the injector 127 disposed on the downstream side of the intake port 33 is introduced into the combustion chamber. .

  A valve retainer 35 is provided at the end of each valve stem 31a via a cotter 34, and a biasing force of a valve spring 36 acts on the valve retainer 35. Further, a tappet shim 37 is attached to the upper end opening of the valve retainer 35, and a pressing force by the pressing portion 22 a of the arm member 22 acts through the tappet shim 37.

The exhaust-side valve unit 30 _EX has the same basic configuration as the intake-side valve unit 30 as shown in FIGS.

In the accelerator shaft unit 40, as shown in FIGS. 2 and 5, an accelerator shaft 41 disposed in parallel between the cam shafts 11 and 11 _EX , and an accelerator fork fixed to the accelerator shaft 41 and connected to the cams 13 and 13 _EX. 42.

The accelerator shaft 41 is supported so as to be movable in the axial direction, and is engaged with a driven gear 43 (bevel gear) via a feed screw 41a at one end side. The driven gear 43 is rotatably supported by the cylinder head 2 and meshes with a drive gear 45 (bevel gear) fixed to the output shaft of the accelerator motor 44 as shown in FIG. Incidentally, the accelerator shaft 41, in order to avoid interference with the plug tube 128 which is located between the intake and exhaust side valve unit 30, 30 _EX, where is located on the camshaft 11 side of the intake side.

The accelerator fork 42 extends toward the camshafts 11 and 11 _{EX in the} direction orthogonal to the accelerator shaft 41 and has a bifurcated tip. Further, fork guides 47 and 47 _EX that are rotatable via bearings 46 and 46 _EX are provided at the ends of the cams 13 and 13 _EX . Each bifurcated tip of the accelerator fork 42 is engaged with the engaging groove of the fork guides 47 and 47 _EX . As a result, the cams 13 and 13 _EX slide along the cam shafts 11 and 11 _EX in synchronization with or in synchronization with the movement of the accelerator shaft 41 in the axial direction.

  As shown in FIG. 3, the valve deactivation unit 50 includes a tappet stopper 51 configured to deactivate one of the two intake valves 31 constituting the intake-side valve unit 30. The tappet stopper 51 is inserted into a sleeve 52 attached to the cylinder head 2 and is movable in parallel with the camshaft 11.

  The tip of the tappet stopper 51 has a spherical shape that can be engaged with one end opening of the arm member 22. A shock-absorbing spring 53 that biases the tappet stopper 51 toward the arm member 22 is mounted in the sleeve 52. When the drive shaft 55 is advanced by the drive device 54, the gap between the fork 56 integrated with the drive shaft 55 and the tappet stopper 51 is operated by the urging force of the spring 53, that is, the tappet stopper 51 is advanced to move the valve. To pause. The release of the valve pause is performed by the drive device 54 moving the drive shaft 55 backward and driving the tappet stopper 51 backward via the fork 56.

  Further, as shown in FIG. 7, a release mechanism 60 for releasing the valve pause state by the valve pause unit 50 is provided. The release mechanism 60 includes an arm 61 that bends at a substantially right angle. The bifurcated tip of the arm 61 engages with the tip of the tappet stopper 51, and the roller at the other end contacts the accelerator shaft 41. The arm 61 is rotatably supported at a bent portion by using a predetermined mounting portion 23a of the tappet guide 23, and a spring 62 for urging the other end of the arm 61 toward the accelerator shaft 41 is attached to the rotating shaft portion. The

  A step portion 63 is formed at a predetermined position of the accelerator shaft 41. When the accelerator shaft 41 moves axially in the arrow X direction from the state shown in FIG. 7, the arm 61 moves over the step portion 63 in the arrow R direction. Therefore, even when the release by the drive device 54 is delayed or cannot be released due to control delay or mechanical loss, the tappet stopper 51 can be forcibly moved backward to cancel the valve resting state. it can.

In the valve operating apparatus having the above configuration, when an accelerator grip (or an accelerator pedal) is operated, a signal that detects the accelerator operation is input to a controller (not shown), and the accelerator motor 44 is driven under the control of the controller. Therefore, the rotation of the output shaft of the accelerator motor 44 causes the accelerator shaft 41 to move in the axial direction via the driven gear 43 and the feed screw 41a. The cams 13 and 13 _EX slide along the cam shafts 11 and 11 _EX in conjunction with the movement of the accelerator shaft 41 via the accelerator fork 42. In this embodiment, the valve lift amount and the operating angle are variably controlled in accordance with the accelerator opening on the exhaust side as well as on the intake side.

In this way, the intake / exhaust amount is controlled from the idle rotation range to the fully open range, and intake / exhaust that is most suitable for the engine speed (or vehicle speed) can be performed. For example, when the engine speed is low, the tappet roller 21 abuts against a cam surface of the cams 13 and 13 _EX at a relatively low cam height. When acceleration is performed in this state, that is, when the accelerator is opened, the driven gear 43 is rotated by the operation of the accelerator motor 44, and the accelerator shaft 41 is moved in the direction of the arrow X in FIG. The cams 13 and 13 _EX slide in the direction of the arrow X along the cam shafts 11 and 11 _EX in conjunction with the movement of the accelerator shaft 41 via the accelerator fork 42. As the cams 13 and 13 _EX slide, the tappet rollers 21 and 21 _EX gradually come into contact with a portion having a relatively high cam height, and the amount of valve lift increases.

  On the other hand, by returning the accelerator at the time of deceleration, the valve lift amount is reduced by the reverse operation to the above.

  Note that, in the low and medium speed rotation region of the engine, the movement of one end of the arm member 22 is restricted by the tappet stopper 51 on the intake side. As a result, the arm member 22 swings around the engaging portion with the tappet stopper 51 as a fulcrum, stops one intake valve 31 and lifts only the other intake valve 31 to generate an intake swirl flow in the combustion chamber. In addition, so-called lean burn can be achieved. In this case, the output can be increased by increasing the fuel injection speed.

  In the valve resting state, the arm member 22 swings with the engaging portion with the tappet stopper 51 as a fulcrum, so that the valve lift amount of the other intake valve 31 with respect to the normal valve lift amount that lifts both intake valves 31 Will increase. In the valve resting state, since intake is performed by one of the intake ports 33, the intake resistance itself increases, but the effective valve opening area is increased by increasing the lift amount. As a result, the difference in intake amount due to the valve opening area and the intake resistance at the time of ON / OFF switching of the valve pause can be substantially eliminated, or smooth switching can be performed with a small amount.

  When the accelerator shaft 41 moves in the axial direction by a predetermined amount beyond the low / medium speed rotation region of the engine, the arm 61 is rotated by the step portion 63 of the accelerator shaft 41 as described above, and the tappet stopper 51 is moved backward to set the valve. The hibernation state can be forcibly released.

  In the valve operating apparatus in the first embodiment described above, the tappet guide 23 can be moved and fixed in the axial direction of the valve stem 31a, and the position of the tappet guide 23 can be adjusted to In most of the region B in the axial direction, the cam 13 and the tappet roller 21 are not in contact with each other in the non-lift region. In this case, when there is no lift, the outer peripheral surface of the tappet roller 21 does not make point contact with the cam 13, but the arm member 22 of the tappet roller 21 makes line contact or surface contact with the tappet guide 23 so that the tappet roller 21 is on the cam 13 side. The movement is restricted, so that dance is prevented and wear can be reduced. More specifically, the gap between the arm member 22 of the tappet roller 21 and the tappet guide 23 is set to be equal to the tappet gap or + α (for example, about 0.05 mm) to ensure valve sealability during thermal expansion, The cam 13 and the tappet roller 21 are not in contact with each other in the non-lift region.

  Thus, since the cam 13 and the tappet roller 21 are not in contact with each other in the non-lift region in almost the region B in the axial direction of the cam 13, the center of the convex cross section that is the outer peripheral surface of the tappet roller 21 in the non-lift region. It is possible to prevent the portion (near the contact angle of 0 degree) from being hit by minute vibrations and to prevent fretting corrosion (fine movement wear).

  Further, in the region B of the cam 13, the profile accuracy and surface roughness may be poor. As described above, the diameter of the portion excluding the cam crest and the ramp portion is made smaller than the base circle so that no processing is performed. Alternatively, since only the centering process is performed, the processing time can be greatly shortened. In the region A of the cam 13, the base circle portion is set so that the valve lift is zero, and finishing is performed in the same manner as the cam crest and the ramp portion. It can be performed.

  Furthermore, when adjusting the gap between the tappet roller 21 and the tappet guide 23, the lock nut 26 is rotated several times (a few rotations) to quickly adjust to the desired gap and locked with the nut 27. The gap can be adjusted without taking time. Further, by loosening the nuts 26 and 27 and increasing the gap between the tappet roller 21 and the tappet shim 37, it is possible to easily replace the shim when adjusting the shim thickness without removing the camshaft 11.

(Second Embodiment)
Similarly to the first embodiment, the second embodiment is configured such that the cam 13 and the tappet roller 21 are not in contact with each other in the non-lift region, and the center of the convex convex section that is the outer peripheral surface of the tappet roller 21 is. This prevents fretting corrosion (fine movement wear) from occurring in the portion (near the contact angle of 0 degree). In the following description, differences from the first embodiment will be mainly described, and the same reference numerals are given to the components described in the first embodiment, and detailed description thereof will be omitted.

  8 is a cross-sectional view showing the main part of the valve gear in the second embodiment, FIG. 9 is a cross-sectional view taken along the line AA in FIG. 8, and FIG. 10 is a cross-sectional view taken along the line BB in FIG. FIG. 11 is a sectional view taken along the line CC of FIG. 12 is a view showing the tappet guide 23, and FIG. 13 is a view showing a release mechanism 60 for releasing the valve resting state.

  In the second embodiment, in the cam / camshaft unit 10 on the intake side (and exhaust side), the cam 13 has a cross section having a diameter smaller than that of the base circle, next to the minimum lift portion (the portion having the lowest cam height). A shim attaching / detaching surface 13b having a portion is formed. In addition, in the state where the cam 13 is at the minimum lift position (see FIG. 9), a space 16 is secured next to the maximum lift portion (the portion with the highest cam height) of the cam 13. Therefore, by sliding the cam 13 in the direction of the space 16, the shim attachment / detachment surface 13 b can be positioned on the tappet roller 21 of the tappet unit 20.

  Further, as described in the first embodiment, in most of the region (region B shown in FIG. 11) in the axial direction of the cam 13 on the intake side, the portion of the cam 13 excluding the cam crest and the ramp portion. The diameter is made smaller than the base circle, and the portion excluding the cam crest and the ramp portion is not processed (for example, if the cam 13 is a cast-forged product, it remains cast forged), or only the centering process is performed. Has been given. However, a partial region at the tip of the cam 13 in the axial direction (region A shown in FIG. 11) is a base circle portion that makes the valve lift amount zero, and is finished in the same manner as the cam crest and ramp portion. Yes.

  In the second embodiment, in the tappet unit 20 on the intake side (and exhaust side), the tappet guide 23 can be moved and fixed in the axial direction of the valve stem 31a as in the first embodiment. Instead of the configuration, as shown in FIG. 12, the tappet guide 23 is fixed to the cylinder head 2 via the mounting bolt 29.

  On the other hand, on the side surface of the tappet guide 23, a pair of restriction arms 291 that are located above the arm member 22 and restrict the movement of the arm member 22 toward the cam 13 are provided. One end of the restriction arm 291 is rotatably supported on the side surface of the tappet guide 23. The height of the other end of the restriction arm 291 can be adjusted. In other words, the adjuster bolt 293 is fastened to the end surface of the regulating arm 291 having a spherical shape via the concave washer 292, and the regulating arm 291 is rotated around one end by adjusting the position of the adjuster bolt 293. Thus, the other end can be raised or lowered, and the restriction position of the arm member 22 can be adjusted.

  Further, the inside of the upper surface of the tappet guide 23 is inclined so as to increase from the left end to the right end in FIG.

  In the valve operating apparatus according to the second embodiment described above, the restriction position of the arm member 22 by the restriction arm 291 is adjusted, and the cam 13 is in the non-lift range in the almost area B in the axial direction of the cam 13. The tappet roller 21 is not contacted. In this case, when there is no lift, the outer peripheral surface of the tappet roller 21 does not make point contact with the cam 13, but the arm member 22 of the tappet roller 21 makes line contact with the restriction arm 291 and the tappet roller 21 moves to the cam 13 side. Is restricted, and dance is prevented, and wear can be reduced. More specifically, the gap between the arm member 22 of the tappet roller 21 and the restricting arm 291 is set to be equal to or + α as the tappet gap to ensure valve sealing during thermal expansion, and in the non-lift region, the cam 13 The tappet roller 21 is not contacted.

  Thus, since the cam 13 and the tappet roller 21 are not in contact with each other in the non-lift region in almost the region B in the axial direction of the cam 13, the center of the convex cross section that is the outer peripheral surface of the tappet roller 21 in the non-lift region. It is possible to prevent the portion (near the contact angle of 0 degree) from being hit by minute vibrations and to prevent fretting corrosion (fine movement wear).

  In this case, in the first embodiment, it is necessary to adjust the position of the tappet guide 23 by the lock nuts 26 and the main nuts 27 at the four corners of the tappet guide 23, whereas in the second embodiment, two positions are required. The position of the restriction arm 291 can be adjusted by the adjuster bolt 293, and the adjustment work can be saved.

  Similarly to the first embodiment, in the region B of the cam 13, the profile accuracy and surface roughness may be poor, and the diameter of the portion excluding the cam crest and the ramp portion as described above is the base circle. Since the machining is made smaller and no machining is performed or only the centering process is performed, the machining time can be greatly shortened. In the region A of the cam 13, the base circle portion is set so that the valve lift is zero, and the finishing process is performed in the same manner as the cam crest and the ramp portion. It can be performed.

  Further, on the intake side (or exhaust side), the shim thickness of one of the two valves is fixed, and the gap is adjusted by adjusting the thickness of the other shim. At that time, the adjuster bolt 293 on one side is adjusted. Loosen and bring the restriction position of one end of the arm member 22 closer to the cam 13 side. Further, the cam 13 is slid in the direction of the space 16 so that the shim attaching / detaching surface 13 b is positioned on the tappet roller 21. In this state, as shown in FIG. 10, the arm member 22 can be largely swung, and the arm member 22 can be tilted along the inner side of the upper surface of the tappet guide 23. As a result, one end of the arm member 22 is raised and a gap can be ensured between the arm member 22 and the tappet shim 37, so that the jig 129 can be inserted and the tappet shim 37 can be removed or attached. The shim can be easily exchanged without removing 11. In this case, as shown in FIG. 14, if a notch 35 a into which the tip of the jig 129 can be inserted is formed in the upper opening side of the valve retainer 35, the jig 129 is attached to the lower surface of the tappet shim 37. The tappet shim can be easily removed by lever principle.

(Third embodiment)
In the first and second embodiments, the cam 13 and the tappet roller 21 are not in contact with each other in the non-lift range to prevent fretting corrosion (fine wear) from occurring. In this embodiment, conversely, fretting corrosion (fine wear) is provided by providing an urging means such as a spring 38 that applies an urging force to the tappet roller 21 so that the tappet roller 21 is always in contact with the cam 13. It prevents it from occurring. In the following description, differences from the first embodiment will be mainly described, and the same reference numerals are given to the components described in the first embodiment, and detailed description thereof will be omitted.

  15 is a cross-sectional view showing the main part of the valve gear in the third embodiment, FIG. 16 is a cross-sectional view taken along the line AA in FIG. 15, and FIG. 17 is a cross-sectional view taken along the line BB in FIG. 18 is a cross-sectional view taken along the line CC of FIG. FIG. 19 is a view showing the tappet guide 23.

  In the third embodiment, in the cam / camshaft unit 10 on the intake side (and the exhaust side), the base circle portion is set so that the valve lift amount is zero in the entire axial direction region of the cam 13, and the cam crest and ramp Finished as well as the part. The cam 13 and the tappet roller 21 are not brought into non-contact in the non-lift region by the tappet guide 23 and the restriction arm 291 as in the first and second embodiments, but the cam 13 and the tappet roller in the non-lift region. 21 is in contact.

  Here, a spring 38 is mounted between the cotter 34 and the tappet shim 37 in the valve retainer 35. The urging force of the spring 38 acts on the arm member 22 via the tappet shim 37 and applies the urging force to the tappet roller 21 so that the tappet roller 21 is always in contact with the cam 13.

  In the valve operating apparatus according to the third embodiment described above, the urging force is applied to the tappet roller 21 so that the tappet roller 21 is always in contact with the cam 13, so that the tappet roller 21 is not lifted. It is possible to prevent the central portion (near the contact angle of 0 degree) of the convex cross section which is the outer peripheral surface from being hit by minute vibrations, and to prevent fretting corrosion (fine movement wear).

  Further, by using the space in the valve retainer 35 and disposing the spring 38 between the cotter 34 and the tappet shim 37, a spring guide is not required and the size is not increased. Further, since the urging force also acts on the tappet shim 37, the free movement of the tappet shim 37 is restricted in the valve retainer 35, and wear of the valve retainer 35 and the tappet shim 37 can be reduced.

  As mentioned above, although this invention was demonstrated with various embodiment, this invention is not limited only to these embodiment, A change etc. are possible within the scope of the present invention.

It is a figure which shows the structural example of the motorcycle containing the engine periphery which concerns on the example of application of this invention. It is principal part side sectional drawing of the valve operating apparatus in 1st Embodiment. It is sectional drawing which follows the AA line of FIG. It is sectional drawing which follows the BB line of FIG. It is sectional drawing which follows the CC line of FIG. It is a figure which shows the structure around an accelerator motor. It is a figure which shows the cancellation | release mechanism for canceling | releases a valve dormant state. It is a principal part sectional side view of the valve gear in 2nd Embodiment. It is sectional drawing which follows the AA line of FIG. It is sectional drawing which follows the BB line of FIG. It is sectional drawing which follows the CC line of FIG. It is a figure which shows a tappet guide. It is a figure which shows the cancellation | release mechanism for canceling | releases a valve dormant state. It is a top view of a valve retainer. It is a principal part sectional side view of the valve gear in 3rd Embodiment. It is sectional drawing which follows the AA line of FIG. It is sectional drawing which follows the BB line of FIG. It is sectional drawing which follows the CC line of FIG. It is a figure which shows a tappet guide.

Explanation of symbols

1 Engine unit 2 Cylinder head 10 (10 _EX ) Cam / camshaft unit 11 (11 _EX ) Camshaft 13 (13 _EX ) Cam 20 (20 _EX ) Tappet unit 21 (21 _EX ) Tappet roller 22 (22 _EX ) Arm member 23 (23 _EX ) Tappet guide 23b (23b _EX ) Mounting portion 25 (25 _EX ) Guide and fixing bolt 26 (26 _EX ) Set nut 27 (27 _EX ) This nut 28 (28 _EX ) Spring washer 30 (30 _EX ) Valve Unit 31 Intake valve 31 _EX Exhaust valve 31a (31a _EX ) Valve stem 34 (34 _EX ) Cotter 35 (35 _EX ) Valve retainer 37 (37 _EX ) Tappet shim 38 (38 _EX ) Spring 40 Accelerator shaft unit 50 Valve rest unit 60 Release Mechanism 291 (29 1 _EX ) Regulating arm

Claims (12)

The cam surface is formed so that the cam height and the cam working angle continuously change, and the cam is configured to rotate integrally with the cam shaft and to be slidable in the axial direction;
A tappet roller that causes the outer peripheral surface having a convex curved surface to come into rolling contact with the cam and to advance and retract the valve via the valve stem;
A tappet guide for guiding the tappet roller to move only in the axial direction of the valve stem,
The tappet roller is restricted from moving from a predetermined position to the cam side, and the cam and the tappet roller are configured to be in a non-contact area in a non-lift area in a predetermined area in the axial direction of the cam. The valve gear.   The tappet guide restricts the tappet roller from moving from the predetermined position to the cam side, and the tappet guide can be moved and fixed in the axial direction of the valve stem. The valve gear according to claim 1.   Urging means for applying an urging force in the axial direction of the valve stem toward the cam side with respect to the tappet guide; and a position-changing restricting means for restricting the tappet guide from moving toward the cam side; The valve operating device according to claim 2, wherein the tappet guide is configured to be fixed by moving in the axial direction of the valve stem.   The restriction member provided in the tappet guide restricts the tappet roller from moving from a predetermined position to the cam side, and the restriction position by the restriction member can be adjusted and fixed. The valve gear according to claim 1.   The tappet guide is provided with a restricting arm that is positioned above the arm member that is arranged so as to have a centering function in the tappet roller and restricts the arm member from moving from the predetermined position to the cam side. The valve operating apparatus according to claim 4, wherein the valve operating apparatus is provided.   6. The valve operating device according to claim 5, wherein one end of the restriction arm is rotatably supported, and the other end is adjustable in height position.   7. The method according to claim 1, wherein in a predetermined region in the axial direction of the cam, a portion excluding the cam crest and the ramp portion is not processed, or only centering processing is performed. The valve operating device described.   7. The valve gear according to claim 6, wherein a diameter of a portion excluding the cam crest and the ramp portion is smaller than that of the base circle in a predetermined region in the axial direction of the cam.   8. The valve operating apparatus according to claim 7, wherein a partial region excluding a predetermined region in the axial direction of the cam is used as a base circle portion that makes the valve lift amount zero. The cam surface is formed so that the cam height and the cam working angle continuously change, and the cam is configured to rotate integrally with the cam shaft and to be slidable in the axial direction;
A tappet roller that causes the outer peripheral surface having a convex curved surface to come into rolling contact with the cam and to advance and retract the valve via the valve stem;
And a biasing means for imparting a biasing force to the tappet roller so that the tappet roller is always in contact with the cam.   A spring is disposed between the cotter and the tappet shim in the valve retainer provided at the end of the valve stem, and the biasing force of the spring is applied to the tappet roller via the tappet shim. The valve gear according to claim 10, wherein An internal combustion engine configured to control intake and exhaust by an intake valve and an exhaust valve,
An internal combustion engine comprising the valve gear according to any one of claims 1 to 11.

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