JP2008157080A - Valve train for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve train for an engine suppressing incorrect motion of a valve even in an engine operational range where oscillation acceleration of an oscillation cam is increased. <P>SOLUTION: The valve train for an engine comprises: the oscillation cam 260 oscillating around a camshaft 210 driven by the engine; and a cam follower 53 pressed by the oscillation cam 260 and oscillated around a fulcrum, and opening a valve train 51 closed by a spring force of a valve spring. The oscillation cam 260 includes a projecting part 260c restricting oscillation of the cam follower 53. The cam follower 53 includes: an over stroke prevention part 53a abutted to the projecting part 260c of the oscillation cam to prevent overstroke; and a recess part 53b preventing interference of the projecting part 260c of the oscillation cam with the cam follower while the valve train 51 is opened. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine valve mechanism.

  As shown in Patent Document 1, there is known an engine valve mechanism that opens and closes a valve by a cam follower that is pressed by a swing cam and strokes.

In such a valve mechanism, the valve is closed by the spring force of the valve spring. The cam follower presses the valve to open the valve against this spring force.
JP 2004-204822 A

  In the high-rotation and high-load operation region, it is necessary to increase the valve opening interval and increase the valve lift, and the swing amount and swing speed of the swing cam increase, and the swing acceleration increases. Therefore, a large inertia force acts on the cam follower pressed by the swing cam. When this inertial force becomes larger than the spring force of the valve spring, the cam follower moves away from the swing cam, and the valve improper movement occurs in which the valve is larger than the set lift amount. The illegal movement of the valve can be suppressed by increasing the spring force of the valve spring. However, if the spring force is increased, the friction of the valve operating system increases and the fuel consumption and the like deteriorate.

  The present invention has been made paying attention to such a conventional problem, and provides an engine valve mechanism capable of suppressing valve improper movement even in an engine operating range where the swing acceleration of the swing cam increases. For the purpose.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention includes a swing cam (260) swinging around a camshaft (210) driven by an engine, and a swing of a valve spring pressed by the swing cam (260) and swinging around a fulcrum. A cam follower (53) for opening a valve (51) that is closed by force, wherein the swing cam (260) swings the cam follower (53). The cam follower (53) includes a restricting convex portion (260c), and the cam follower (53) contacts the convex portion (260c) of the swing cam to prevent an overstroke, and the valve (51) ), And a concave portion (53b) for preventing the convex portion (260c) of the swing cam from interfering with the cam follower.

  According to the present invention, the swing cam is formed with a convex portion that restricts the swing of the cam follower, and the cam follower is brought into contact with the convex portion of the swing cam to prevent the overstroke and the valve closing. Since the concave part of the swing cam prevents the convex part of the swing cam from interfering with the cam follower, the valve overlift (valve movement of the valve) ) Can be prevented. Further, the concave portion of the cam follower prevents the convex portion of the swing cam from interfering with the cam follower when the valve is completely closed.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram showing a first embodiment of a variable valve mechanism according to the present invention.

  In order to stroke the cam follower, for example, a variable valve mechanism disclosed in JP-A-11-107725 may be used. Here, the variable valve mechanism will be briefly described with reference to FIG.

  The variable valve mechanism 200 includes a camshaft 210, a link arm 220, a valve lift control shaft 230, a rocker arm 240, a link member 250, and a swing cam 260. 53 is pressed to open and close the valve.

  The camshaft 210 is rotatably supported on the cylinder head along the engine longitudinal direction. One end of the camshaft 210 is inserted into the cam sprocket 270. The cam sprocket 270 rotates with torque transmitted from the crankshaft of the engine. The camshaft 210 rotates with the cam sprocket 270. The camshaft 210 rotates relative to the cam sprocket 270 by hydraulic pressure, and can change the phase with respect to the cam sprocket 270. With such a structure, the rotational phase of the camshaft 210 relative to the crankshaft can be changed. A cam 211 is fixed to the camshaft 210. The cam 211 rotates integrally with the cam shaft 210. A pair of swing cams 260 connected by pipes are inserted through the camshaft 210. The swing cam 260 swings about the cam shaft 210 as a center of rotation, and causes the cam follower 53 to stroke. In addition, the code | symbol P in a figure is a virtual surface which shows the stroke position by the rocking cam 260 of the cam follower 53. FIG.

  The link arm 220 is supported through the cam 211.

  The valve lift control shaft 230 is disposed in parallel with the camshaft 210. A cam 231 is integrally formed on the valve lift control shaft 230. The valve lift control shaft 230 is controlled by an actuator 280 so as to rotate within a predetermined rotation angle range.

  The rocker arm 240 is supported through the cam 231 and is connected to the link arm 220.

  The link member 250 is connected to the rocker arm 240.

  The swing cam 260 is inserted through the cam shaft 210 and can swing about the cam shaft 210. The swing cam 260 is connected to the link member 250. The swing cam 260 moves up and down, pushes down the cam follower 53 (virtual plane P), and opens and closes the valve.

  Next, the operation of the variable valve mechanism 200 will be described with reference to FIG.

  FIGS. 2A-1 and 2A-2 are views showing a state in which the stroke amount of the cam follower 53 is maximized to maximize the valve lift. FIG. 2A-1 shows a state where the cam nose 260b is at the highest position and the swing direction of the swing cam 260 is reversed. At this time, the cam follower 53 (virtual plane P) is at the upper end position, and the valve train 51 is in a closed state. FIG. 2 (A-2) shows a state where the cam nose 260b is at the lowest position and the swing direction of the swing cam 260 is reversed. At this time, the cam follower 53 (virtual plane P) is at the lower end position, and the valve train 51 is in the maximum lift state.

  2 (B-1) and 2 (B-2) are views showing a state when the stroke amount of the cam follower 53 is minimized. FIG. 2 (B-1) shows a state where the cam nose 260b is at the highest position and the swing direction of the swing cam 260 is reversed. FIG. 2 (B-2) shows a state where the cam nose 260b is at the lowest position and the swing direction of the swing cam 260 is reversed. In the present embodiment, the stroke amount of the cam follower 53 (virtual plane P) is zero, and the lift amount of the valve is zero. Therefore, in FIGS. 2 (B-1) and 2 (B-2), the valve train 51 is always closed regardless of the operation of the swing cam 260.

  In order to increase the lift amount of the valve by increasing the stroke amount of the cam follower 53, the valve lift control shaft 230 is rotated to position the cam 231 as shown in FIGS. And the axis P1 is set below the axis P2. As a result, the entire rocker arm 240 moves downward.

  When the camshaft 210 is rotationally driven in this state, the driving force is transmitted from the link arm 220 → the rocker arm 240 → the link member 250 → the swing cam 260.

  When the cam 211 is on the left side of the camshaft 210 as shown in FIG. 2A-1, the base circle portion 260a of the swing cam 260 is in contact with the cam follower 53 (virtual plane P). At this time, the cam follower 53 is The valve 51 is in the upper end position and is in the maximum lift state.

  As shown in FIG. 2A-2, when the cam 211 is on the right side of the camshaft 210, the cam nose 260b of the swing cam 260 is in contact with the cam follower 53 (virtual plane P). The valve 51 is in the closed position.

  In order to reduce the stroke amount of the cam follower 53 and reduce the valve lift, the valve lift control shaft 230 is rotated and the position of the cam 231 is rotated as shown in FIGS. And the axis P1 is set to the upper right of the axis P2. As a result, the entire rocker arm 240 moves upward.

  When the camshaft 210 is rotationally driven in this state, the driving force is transmitted from the link arm 220 → the rocker arm 240 → the link member 250 → the swing cam 260.

  As shown in FIG. 2 (B-1), when the cam 211 is on the left side of the camshaft 210, the base circle portion 260a of the swing cam 260 comes into contact with the cam follower 53 (virtual surface P).

  As shown in FIG. 2 (B-2), even when the cam 211 is on the right side of the camshaft 210, the base circle portion 260a of the swing cam 260 contacts the cam follower 53 (virtual plane P).

  As described above, when the valve lift control shaft 230 is rotated to raise the position of the cam 231 and the shaft center P1 is set to the upper right of the shaft center P2, the camshaft 210 rotates to swing the swing cam. Even if it moves, the cam follower 53 (virtual plane P) does not stroke, and the valve 51 remains closed.

  FIG. 3 is a diagram showing the valve lift amount and opening / closing timing by the variable valve mechanism 200. The solid line shows the lift amount and opening / closing timing of the valve 51 when the valve lift control shaft 230 is rotated. A broken line is a diagram showing the opening / closing timing of the valve train 51 when the phase of the camshaft 210 with respect to the cam sprocket 270 is changed.

  According to the structure of the variable valve mechanism 200 described above, the lift amount and operating angle of the valve valve 51 can be continuously changed. In this way, by changing the angle of the valve lift control shaft 230 and the phase of the camshaft 210 with respect to the cam sprocket 270, the lift amount and operating angle of the valve train 51 can be changed continuously and freely.

  FIG. 4 is an enlarged perspective view of the vicinity of the swing cam and cam follower of the variable valve mechanism according to the present invention.

  The width of the swing cam 260 of this embodiment is substantially the same as the width of the cam follower 53. A stopper 260 c is provided in the vicinity of the center of the swing cam 260 in the width direction. The width of the stopper 260c of this embodiment is about 1/2 to 1/3 of the width of the cam follower 53.

  An overstroke prevention portion 53a is formed at one end of the cam follower 53 (one end on the pivot pin 52 side). A stopper passing portion 53b is recessed in a part of the upper surface of the cam follower 53 (the surface on which the swing cam 260 slides). As will be described later, the stopper 260c of the swing cam 260 passes through the stopper passage portion 53b.

  FIG. 5 is a diagram for explaining the function and effect of the variable valve mechanism according to the present embodiment. FIG. 5A shows a state in which the base circle portion 260 a of the swing cam 260 is in contact with the cam follower 53. FIG. 5B shows a state where the cam nose 260 b of the swing cam 260 is in contact with the cam follower 53.

  In the state of FIG. 5A, the stopper 260 c formed on the swing cam 260 passes through the stopper passage portion 53 b of the cam follower 53, and the base circle portion 260 a of the swing cam 260 contacts the cam follower 53.

  Then, the swing cam 260 rotates clockwise, the cam nose 260b of the swing cam 260 pushes down the cam follower 53, and the cam follower 53 swings. If the swing cam 260 is rotated slightly to the right from the state of FIG. 5A, the swing amount of the cam follower 53 is small, and the cam follower 53 does not easily overstroke. However, when the amount of rotation of the swing cam 260 increases, the cam follower 53 may overstroke. Since the cam follower 53 of the present embodiment has the overstroke prevention portion 53a, at this time, the overstroke prevention portion 53a contacts the stopper 260c of the swing cam 260 as shown in FIG. Therefore, the operation of the cam follower 53 is restricted and no overstroke occurs.

  As described above, according to the present embodiment, the cam follower 53 is provided with the overstroke preventing portion 53a, and the stopper 260c for restricting the swing of the cam follower 53 is provided on the swing cam 260. With such a structure, the valve overlift (valve movement of the valve) can be prevented even in the operating range where the swing acceleration of the swing cam 260 increases.

  In the variable valve mechanism used in the present invention, the stroke amount of the cam follower 53 varies depending on the swing amount of the swing cam 260 as described above. If the swing cam 260 does not rotate (swing) to the position shown in FIG. 5B, the stroke amount of the cam follower 53 also decreases. Even if the swing amount changes, the stopper 260c is formed in a mountain shape so that the overstroke preventing portion 53a contacts the stopper 260c. The smaller the swing amount of the swing cam 260 and the smaller the stroke amount of the cam follower 53, the more the stopper By making the overstroke preventing portion 53a abut on the top side of 260c, valve overlift (valve motion) can be prevented regardless of the swinging amount of the swinging cam 260.

  Furthermore, the width of the swing cam 260 is substantially the same as the width of the cam follower 53, and the stopper 260c is provided in the vicinity of the center in the width direction of the swing cam 26, so that the cam follower 53 contacts the swing cam 260 and the stopper 260c. Will not fall over when you do.

  Further, the sliding surface of the swing cam 260 to the cam follower 53 is arranged on the valve side as viewed from the swing center of the swing cam 260, thereby reducing the lever ratio of the cam follower 53 at the start of the valve lift. The contact load can be reduced.

  In addition, the overstroke prevention portion 53a of the cam follower 53 and the stopper 260c of the swing cam 260 gradually approach each other as the swing amount of the swing cam 260 increases, so that the impact load can be reduced and the collision sound can be reduced. Is less likely to occur.

(Second Embodiment)
FIG. 6 is a view showing a second embodiment of the variable valve mechanism according to the present invention.

  In the following description, the same reference numerals are given to portions that perform the same functions as those in the above-described embodiment, and overlapping descriptions are omitted as appropriate.

  The overstroke preventing portion 53a of the present embodiment is formed closer to the center than one end of the cam follower 53 (one end on the pivot pin 52 side).

  The swing cam 260 is provided with a cam follower stroke amount adjusting groove 260d, not the stopper 260c, in the vicinity of the center in the width direction. The width of the cam follower stroke amount adjusting groove 260 d is about ½ to ３ of the width of the cam follower 53.

  FIG. 7 is a diagram for explaining the function and effect of the variable valve mechanism according to the present embodiment. FIG. 7A shows a state in which the valve 51 is closed. FIG. 7B shows a state in which the cam nose 260b of the swing cam 260 is in contact with the cam follower 53 and the valve train 51 is opened.

  7A, the valve train 51 is closed by the spring force of the valve spring, and the cam follower 53 is at the uppermost position. At this time, there is a slight gap between the base circle portion 260 a of the swing cam 260 and the cam follower 53. There is also a slight gap between the overstroke prevention portion 53a of the cam follower 53 and the base circle portion 260a of the swing cam 260.

  Then, as shown in FIG. 7B, the swing cam 260 rotates clockwise, and the cam nose 260b of the swing cam 260 pushes down the cam follower 53, and the overstroke prevention portion 53a of the cam follower 53 is recessed in the swing cam 260. It enters the cam follower stroke amount adjusting groove 260d. At this time, there is a slight gap between the overstroke preventing portion 53a and the groove surface of the cam follower stroke amount adjusting groove 260d. However, as the swinging amount of the swing cam 260 increases, the overstroke preventing portion 53a and the cam follower stroke are increased. The amount adjusting groove 260d gradually approaches. When the cam follower 53 is likely to overlift, the overstroke prevention portion 53a comes into contact with the groove surface of the cam follower stroke amount adjusting groove 260d, and the operation of the cam follower 53 is restricted to prevent the overstroke of the cam follower 53. 51 overlift is prevented.

  The clearance between the overstroke prevention portion 53a and the groove surface of the cam follower stroke amount adjusting groove 260d is set so as to be small only at the maximum swing amount of the valve 51 at the maximum operating angle of the variable valve mechanism 200. The overstroke of 53 may be prevented only at the maximum swing amount of the valve train 51 when the variable valve mechanism 200 is at the maximum operating angle.

  Also in this embodiment, the operation of the cam follower 53 is restricted, and the overlift (valve illegal movement) can be prevented even in the operating range where the swing cam swing acceleration is increased. According to the present embodiment, since the cam follower stroke amount adjusting groove 260d is formed in the swing cam 260, there is no part that interferes with the cam follower 53 unlike the stopper 260c of the first embodiment. Therefore, the cam follower 53 can be easily formed. In addition, the inertia weight of the swing cam 260 can be reduced, and it is not necessary to provide a notch on the contact surface of the cam follower 53, and the contact surface of the swing cam tip portion that has a high surface pressure during low rotation and the cam follower. The contact width with the contact surface of 53 can be increased, and wear and seizure can be prevented.

  Even if the swinging amount of the swinging cam 260 changes, the cam follower stroke increases as the swinging amount of the swinging cam 260 increases and the stroke amount of the cam follower 53 increases so that the overstroke preventing portion 53a contacts the cam follower stroke amount adjusting groove 260d. The cam follower 53 is formed on the bottom side of the cam follower stroke amount adjusting groove 260d of the swing cam 260 (the cam follower stroke amount adjusting groove is deeper) as the maximum swing amount of the cam follower 53 is larger. The overstroke preventing portion 53a is in contact with each other. In this way, the valve overlift (valve movement) can be prevented regardless of the swing amount of the swing cam 260.

  Further, in the initial state when the valve train 51 starts to lift, there is a slight gap between the overstroke prevention portion 53a and the groove surface of the cam follower stroke amount adjusting groove 260d, and the swing amount of the swing cam 260 increases. Accordingly, when the cam follower 53 is about to overstroke when the swing cam 260 pushes down the cam follower 53 due to the close proximity of the groove surface of the overstroke preventing portion 53a and the cam follower stroke adjusting groove 260d, the overstroke prevention is always performed. The portion 53a comes into contact with the groove surface of the cam follower stroke amount adjusting groove 260d, and the overstroke of the cam follower 53 is prevented, thereby preventing the valve 51 from being overlifted. Furthermore, when the overstroke prevention unit 53 comes into contact with the groove surface of the cam follower stroke amount adjusting groove 260d, it is possible to suppress impact load and impact sound.

  On the other hand, the clearance between the overstroke prevention portion 53a and the cam follower stroke amount adjusting groove 260d is set to be small only at the maximum swing of the valve 51 at the maximum operating angle of the variable valve mechanism 200. The overstroke prevention unit 53 is made small and the cam follower stroke amount adjusting groove 260d is shallowly formed by designing to prevent the overstroke only at the maximum swing of the valve 51 at the maximum operating angle of the variable valve mechanism 200. Therefore, a small and lightweight valve system can be formed.

  Further, since the cam follower stroke amount adjusting groove 260d is provided in the vicinity of the center of the swing cam 26 in the width direction, the cam follower 53 does not fall when it comes into contact with the cam follower stroke amount adjusting groove 260d.

(Third embodiment)
FIG. 8 is a view showing a third embodiment of the variable valve mechanism according to the present invention.

  The overstroke prevention part 53a of this embodiment is closer to the center than one end (one end on the pivot pin 52 side) of the cam follower 53, and the tip is formed in a bifurcated manner.

  Further, the cam follower stroke amount adjusting portion 260e is formed on the swing cam 260, leaving the vicinity of the center in the width direction.

  FIG. 9 is a diagram for explaining the effects of the variable valve mechanism of the present embodiment. FIG. 9A shows a state in which the valve 51 is closed. FIG. 9B shows a state where the cam nose 260b of the swing cam 260 is in contact with the cam follower 53 and the valve train 51 is opened.

  In the state of FIG. 9 (A), the valve train 51 is closed by the spring force of the valve spring, and the cam follower 53 is in the uppermost position. At this time, there is a slight gap between the base circle portion 260 a of the swing cam 260 and the cam follower 53. There is also a slight gap between the overstroke prevention portion 53a of the cam follower 53 and the base circle portion 260a of the swing cam 260.

  Then, as shown in FIG. 9B, the swing cam 260 rotates clockwise, and the cam nose 260b of the swing cam 260 pushes down the cam follower 53, and the overstroke prevention portion 53a of the cam follower 53 is recessed in the swing cam 260. Enters the cam follower stroke amount adjusting groove 260e. At this time, there is a slight gap between the overstroke preventing portion 53a and the groove surface of the cam follower stroke amount adjusting groove 260e. However, as the swinging amount of the swing cam 260 increases, the overstroke preventing portion 53a and the cam follower stroke are increased. The amount adjusting groove 260e gradually approaches. When the cam follower 53 is likely to overlift, the overstroke preventing portion 53e comes into contact with the groove surface of the cam follower stroke amount adjusting groove 260d, and the operation of the cam follower 53 is restricted to prevent the overstroke of the cam follower 53, and thus the valve 51 overlift is prevented.

  According to the present embodiment, the overstroke preventing portion 53a has a bifurcated tip. In this way, since the overstroke prevention unit 53a moves so as to sandwich the cam follower stroke amount adjustment unit 260e, the overstroke prevention unit 53a can be prevented from falling.

  Without being limited to the embodiments described above, various modifications and changes are possible within the scope of the technical idea, and it is obvious that these are also included in the technical scope of the present invention.

  For example, in the second embodiment, the cam follower stroke amount adjusting groove 260d is formed in the vicinity of the center of the swing cam 26 in the width direction, but the cam follower stroke amount adjusting groove 260d is formed on one side of the swing cam 260. Also good. In this way, the cam follower stroke amount adjusting groove 260d can be easily formed by using a grindstone only on one side of the swing cam 260.

  In addition, when the cam follower stroke amount adjusting groove 260d is formed on one side of the swing cam 260, the overstroke preventing portion 53a is also provided biased to the cam follower 53, so the overstroke preventing portion 53a and the cam follower stroke amount are provided. When the adjustment groove 260 d comes into contact with the adjustment groove 260 d, a force in the falling direction easily acts on the cam follower 53. Therefore, in such a case, the cam follower 53 is not supported by the pivot pin 52, but the cam follower 53 may be supported by a shaft provided in parallel with the cam shaft as shown in FIG. 10A is a view in the A direction of FIG. 10B, and FIG. 10B is a cross-sectional view taken along the line BB of FIG. 10A.

  Alternatively, as shown in FIG. 11, even if the cam follower 53 is formed in a Y shape that is bifurcated from the base 53c to the tip, and the base 53c of the Y-shaped cam follower 53 is supported by the pivot pin 52, the force of the cam follower 53 in the falling direction Can be suppressed. 11A is a view in the A direction of FIG. 11B, and FIG. 11B is a cross-sectional view taken along the line BB of FIG. 11A.

It is a figure which shows 1st Embodiment of the variable valve mechanism by this invention. It is a figure explaining operation | movement of a variable valve mechanism. It is a figure which shows the lift amount and opening / closing timing of the valve operating by a variable valve operating mechanism. FIG. 3 is an enlarged perspective view of the vicinity of a swing cam and a cam follower of the variable valve mechanism according to the present invention. It is a figure explaining the effect of the variable valve mechanism of this embodiment. It is a figure which shows 2nd Embodiment of the variable valve mechanism by this invention. It is a figure explaining the effect of the variable valve mechanism of 2nd Embodiment. It is a figure which shows 3rd Embodiment of the variable valve mechanism by this invention. It is a figure explaining the effect of the variable valve mechanism of 3rd Embodiment. It is a block diagram of the variable valve mechanism of other embodiment. It is a block diagram of the variable valve mechanism of other embodiment.

Explanation of symbols

51 Valve 52 Pivot Pin 53 Cam Follower 53a Overstroke Prevention Part 53b Stopper Passing Part (Recess)
200 Variable Valve Mechanism 210 Cam Shaft 220 Link Arm 230 Valve Lift Control Shaft 240 Rocker Arm 250 Link Member 260 Oscillating Cam 260c Stopper (Protrusion)

Claims (19)

A swing cam that swings around a camshaft driven by an engine;
A cam follower that is pressed by the swing cam and swings around a fulcrum and opens a valve that is closed by the spring force of a valve spring;
A valve mechanism for an engine having
The swing cam includes a convex portion that restricts swing of the cam follower,
The cam follower
An overstroke prevention part that prevents the overstroke by contacting the convex part of the swing cam;
A concave portion that prevents the convex portion of the swing cam from interfering with the cam follower during the closing of the valve.
An engine valve mechanism characterized by that. The swing cam can freely change the swing amount, and adjusts the maximum swing amount of the cam follower according to the swing amount,
The convex portion of the swing cam regulates the swing of the cam follower so that the cam follower does not swing more than the maximum swing amount regardless of the maximum swing amount of the cam follower.
The valve operating mechanism for an engine according to claim 1. The over-stroke prevention part of the cam follower comes into contact with the top side of the convex part of the swing cam as the maximum swing amount of the cam follower is smaller.
The valve operating mechanism for an engine according to claim 2. The convex portion of the rocking cam is formed such that the central axis in the width direction coincides with the central axis in the width direction of the rocking cam.
The valve operating mechanism for an engine according to any one of claims 1 to 3, wherein As the swing amount of the swing cam increases, the overstroke prevention portion of the cam follower and the convex portion of the swing cam gradually approach each other.
The engine valve operating mechanism according to any one of claims 1 to 4, wherein the valve operating mechanism of the engine is characterized in that: A swing cam that swings around a camshaft driven by an engine;
A cam follower that is pressed by the swing cam and swings around a fulcrum and opens a valve that is closed by the spring force of a valve spring;
A valve mechanism for an engine having
The camshaft includes a recess that restricts swinging of the cam follower,
The cam follower includes an overstroke prevention unit that abuts against a recess of the swing cam to prevent overstroke,
An engine valve mechanism characterized by that. The swing cam can freely change the swing amount, and adjusts the maximum swing amount of the cam follower according to the swing amount,
The recess of the swing cam regulates the swing of the cam follower so that the cam follower does not swing more than the maximum swing amount regardless of the maximum swing amount of the cam follower.
The valve mechanism for an engine according to claim 6. The cam follower overstroke prevention portion abuts against the bottom side of the recess of the swing cam as the maximum swing amount of the cam follower increases.
8. The valve operating mechanism for an engine according to claim 7. As the swing amount of the swing cam increases, the overstroke prevention portion of the cam follower and the recess portion of the swing cam gradually approach each other.
The valve operating mechanism for an engine according to any one of claims 6 to 8, wherein The center axis in the width direction of the recess of the swing cam is formed so as to coincide with the center axis in the width direction of the swing cam.
The engine valve operating mechanism according to any one of claims 6 to 9, wherein the engine valve operating mechanism is provided. The recess of the swing cam is formed on one side surface of the swing cam.
The engine valve operating mechanism according to any one of claims 6 to 9, wherein the engine valve operating mechanism is provided. The swing cams are a pair of swing cams that open and close two valve valves of the same cylinder,
The recess of the swing cam is formed on a side surface on the side where the pair of swing cams face each other.
The valve operating mechanism for an engine according to claim 11. The cam follower overstroke prevention portion has a bifurcated tip.
The recesses of the swing cam are formed on both side surfaces of the swing cam.
The valve mechanism for an engine according to claim 6. The pressing portion of the cam follower by the swing cam is on the valve operating side with respect to the swing center of the cam follower.
The engine valve mechanism according to any one of claims 1 to 13, wherein the valve operating mechanism is an engine valve mechanism. The over-stroke prevention part of the cam follower prevents the cam follower from being separated from the swing cam and opening the valve.
15. The valve operating mechanism for an engine according to any one of claims 1 to 14, wherein: The fulcrum of the cam follower is a pivot pin,
The valve operating mechanism for an engine according to any one of claims 1 to 15, wherein: The fulcrum of the cam follower is a shaft provided in parallel with the camshaft.
The valve operating mechanism for an engine according to any one of claims 1 to 15, wherein: The cam follower simultaneously opens and closes a pair of valves.
The valve operating mechanism for an engine according to any one of claims 1 to 17, characterized in that: A link arm supported by being inserted through the camshaft;
A rocker arm connected to the link arm and swingable about a cam of the valve lift control shaft;
A link member connecting the rocker arm and the swing cam;
With
In the swing cam, the swing center position of the rocker arm is changed, and the swing amount is arbitrarily adjusted.
The engine valve mechanism according to any one of claims 1 to 18, wherein the engine valve mechanism is characterized in that:

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