JP3870839B2 - Engine valve gear - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine valve gear.
[0002]
[Prior art]
In order to improve fuel efficiency and output in an automobile engine, there has been devised a variable valve operating device that changes the opening / closing timing and lift amount of an intake valve and an exhaust valve with respect to a crank angle in accordance with an operating state. For example, a so-called divided tappet is provided in which a plurality of cams are provided for one valve, and the tappet is divided into a plurality of cams so as to be in sliding contact with a specific cam among the plurality of cams according to the operating state. One of them is a variable valve operating device.
[0003]
An example is the German published patent DE 19721208 (FIG. 8). FIG. 8 shows a cross section of the center portion of the tappet 82 as viewed at right angles to the camshaft axis. This is a tappet having an inner tappet 82a and an annular outer tappet 82b disposed so as to surround the inner tappet 82a, and a mechanism capable of locking the inner tappet 82a and the outer tappet 82b in the hole 83 and switching them to an unlocked state. The tappet outer peripheral wall 85 is provided with a pin member 86 in the same direction as the camshaft axis. The pin member 86 is a detent member that prevents the tappet 82 from rotating in the circumferential direction within the tappet guide hole provided in the cylinder head. The rotation preventing member is in a situation where it is difficult to increase its size from the viewpoints of downsizing and multiple valves of the engine and lightening of the tappet.
[0004]
On the other hand, cylinder heads that house tappets are often made of aluminum alloy for light weight and heat dissipation, and between the guide groove of the tappet guide hole that is in sliding contact with the non-rotating member when the engine is started or at high speed rotation. Wear tends to proceed, and there is a possibility that a problem of biting of the rotation preventing member accompanying the sag of the guide groove may occur.
[0005]
The tappet shown in FIG. 8 has a hydraulic lash adjuster (HLA) so that the tappet clearance can be automatically adjusted by hydraulic pressure, but an HLA is provided in order to reduce the weight and cost of the tappet. A so-called mechanical lash adjuster (MLA) is used. This MLA type is not specifically shown, but how to measure and adjust the tappet clearance will be explained. First, the reference shim is placed on the valve stem end, the tappet is received in the tappet guide hole, and the cam is assembled to the cylinder head. After attaching, a thickness gauge (gap gauge) is inserted between the top plate of the tappet (sliding contact surface with the cam) and the cam, and it is measured whether the tappet clearance is within a predetermined value. And when it is not within a predetermined value, it is recombined with the shim of the thickness which becomes a predetermined value. In the case of a divided tappet, this work is difficult to insert the thickness gauge because there are a plurality of cams, and the workability is extremely poor.
[0006]
[Problems to be solved by the invention]
As described above, in the tappet constituting the valve gear of the engine, the present invention provides the rotation stopper member main body for restricting the rotation of the tappet in the circumferential direction on the peripheral wall of the tappet guide for storing the tappet. The problem is to prevent problems such as biting into a guide groove that slides into contact with the non-rotating member body, to suppress the length of the engine in the camshaft direction, and to facilitate adjustment and measurement of the tappet clearance during engine assembly. And
[0007]
[Means for Solving the Problems]
The present invention Pertaining to The valve operating apparatus of an engine includes a variable mechanism that changes a valve lift characteristic by providing a lock mechanism that engages and disengages the tappet constituent member, wherein a tappet whose outer shape is substantially cylindrical is formed by a plurality of tappet constituent members. In the valve operating apparatus, a tappet guide hole having a guide groove extending in the sliding direction of the tappet and accommodating the tappet is formed in the cylinder head, and the tappet is provided in the tappet in the guide groove so that the tappet rotates in the circumferential direction. A rotation preventing member is inserted, the rotation preventing member is inserted into the guide groove and has a main body portion having a sliding surface extending in the sliding direction, and a shaft portion for supporting the main body portion on the tappet. And the main body is swingable about the axis of the shaft.
[0008]
this According to the configuration, since the rotation preventing member supported by the tappet is inserted into the guide groove formed in the tappet guide hole of the cylinder head, the tappet does not rotate in the circumferential direction. The valve lift characteristic enabled by the disengagement of the tappet component can be maintained with high reliability. Further, the anti-rotation member has a structure including a main body portion having a sliding contact surface that is inserted into the guide groove and extends in the sliding direction, and a shaft portion that supports the main body portion on the tappet, and the anti-rotation member main body. Since the part can swing around the axis of the shaft part, the area where the guide groove comes into contact with the sliding surface of the non-rotating member main body increases, the guide groove sags or abnormal wear, or the anti-rotation member Problems such as the main body biting into the guide groove can be avoided.
[0009]
Further, according to the present invention In the valve operating apparatus of the engine, the guide groove has a substantially partial circular cross section when viewed from the tappet sliding direction, the main body portion is a partial cylindrical shape that is inserted into the guide groove, and the shaft portion is orthogonal to the main body portion. It is a shaft that forms a columnar shape extending in the direction to be inserted, and is supported by being inserted into a hole provided in the tappet.
[0010]
this According to the configuration, the guide groove and the non-rotating main body portion inserted into the guide groove have a substantially partial circular shape and a partial cylindrical shape, respectively. In addition, it is possible to further improve the effect of avoiding problems such as abnormal wear, or the fact that the rotation stopper member main body bites into the guide groove.
[0011]
Furthermore, according to the present invention A valve operating apparatus for an engine includes a plurality of types of cams having different cam nose shapes corresponding to a plurality of tappet constituent members for one tappet, and a plurality of tappets extending in a sliding direction corresponding to each cam. The divided tappet structure is divided into two, and the plurality of divided tappets are engaged and disengaged by the operation of the lock mechanism, so that the valve is driven with different characteristics.
[0012]
this According to the configuration, a plurality of types of cams having different cam nose shapes are provided for one tappet, and a plurality of divided tappets corresponding to the plurality of types of cams are configured. Since it is disengaged by operation, optimum valve opening / closing characteristics corresponding to the high-speed rotation and low-speed rotation of the engine can be obtained. For example, fuel consumption, output, or exhaust gas characteristics can be dramatically improved.
[0013]
Furthermore, according to the present invention A valve operating apparatus for an engine is provided with a center cam and two side cams having different shapes of the center cam and the cam nose in one tappet, and the tappet extends in a direction perpendicular to the cam shaft in correspondence with each cam in a substantially rectangular view. A lock that has a center tappet in the shape and side tappets on both sides of the center tappet, and is configured so that both tappets can be engaged and disengaged by a lock mechanism extending in the camshaft direction, and a detent member is formed on one side tappet It is attached to and supported by a bush attached to the mechanism hole.
[0014]
this According to the configuration, since the anti-rotation member is attached and supported by the bush attached to the lock mechanism hole formed in the one side tappet, it is not necessary to separately process a hole for supporting the anti-rotation member. In addition, there is no need to newly provide another bush, and the cost can be reduced.
[0015]
【The invention's effect】
As described above, according to the present invention, in the tappet constituting the valve gear of the engine, the rotation stopper member main body portion that restricts the rotation of the tappet in the circumferential direction is provided in the tappet guide that houses the tappet. It is possible to prevent problems such as biting into the guide groove that is in sliding contact with the rotation stopper member main body, and to easily adjust and measure the tappet clearance during engine assembly.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the structure of the cam and the tappet will be described with reference to FIG. 1 showing the valve operating apparatus for the engine according to the present embodiment. 1A is a plan view of a sliding contact surface with a tappet cam, FIG. 1B is a front view thereof, and FIG. 1C is a side view thereof.
[0017]
The valve gear according to the present embodiment includes a tappet guide hole 3 provided in the cylinder head 2 of the engine, a tappet 1 slidably accommodated in the tappet guide hole 3, the tappet 1, and a shim 5. The cam 4 is provided to reciprocate the valve V in the tappet axial direction.
[0018]
The cam 4 is provided with three cams for one tappet 1, that is, a center cam 4 a that rotates and slidably contacts with a substantially central portion of the tappet 1, and is provided so as to sandwich the center cam 4 a. The side cams 4b and 4c are in sliding contact with the center cam 4a and the side cams 4b and 4c have cam nose heights set so that the lift amount of the valve V is different. Specifically, the center cam 4a is a cam for high-speed rotation of the engine, the side cams 4b and 4c are cams for low-speed rotation of the engine, and the cam nose height of the center cam 4a is set higher than the cam nose height of the side cams 4b and 4c.
[0019]
The reason why a plurality of cams having different cam nose heights is provided in order to cope with fuel efficiency reduction, high output, or reduction of harmful exhaust gas. Therefore, each of the center cam 4a or the side cams 4b and 4c is provided. The tappet 1 also has a divided structure so as to be slidably contacted.
[0020]
As can be seen from FIG. 1A, the slidable contact surface portion of the tappet 1 with the cam is divided into three parts, but the structure has a top plate slidable contact surface 1aa that is slidably contacted with the center cam 4a. (Protrusions that slide in contact with the ends of the side tappet 1s at both ends, and prevent sliding wear so that the ends of the side tappet do not slide directly into the tappet guide hole 3 to prevent uneven wear. The center tappet 1a having a substantially I shape) and the side tappet 1s having the top plate sliding contact surfaces 1bb and 1cc slidably contacting the side cams 4b and 4c. In other words, the tappet 1 has a side tappet 1s that is formed by cutting a top plate portion and a circumferential portion of a predetermined width from a substantially ceiling plate cylindrical member over a predetermined height in the axial direction, and slightly removed portions. The center tappet 1a, which is a member having substantially the same shape as that deleted with the clearance, is combined. In the following description, of the side tappets 1s, the side tappet on the side having the top plate sliding contact surface 1bb is referred to as a side tappet 1b, and the side tappet on the side having the top plate sliding contact surface 1cc is referred to as a side tappet 1c (see FIG. 2).
[0021]
Further, the center tappet 1a and the side tappets 1b, 1c are provided with a lock member that is actuated by oil pressure inside the tappet so that the tappet can be engaged and disengaged. 1 is extended.
[0022]
Further, the side tappet 1b is provided with a rotation prevention member main body portion 6 for restricting the tappet from rotating in the circumferential direction so as to protrude from the circumference of the tappet 1. In the tappet guide hole 3 of the cylinder head 2, a guide groove 3 a having a substantially partial circular cross section in the tappet sliding direction is provided so as to be narrowed in the tappet sliding direction. In addition, a detailed description is separately added about the rotation prevention member and the guide groove 3a.
[0023]
The outline of the valve gear according to the present embodiment has been described above. Next, the structure will be described based on FIG. 2 showing details of the tappet. 2A is a plan view of a tappet according to the present invention, FIG. 2B is a cross-sectional view taken along line XX in FIG. 2A for representing a lock member and a detent member main body, and FIG. It is a YY sectional view in).
[0024]
2A, as described above, the tappet 1 has the center tappet 1a and the side tappets 1b and 1c positioned so as to sandwich the center tappet 1a. From the side tappet 1b, the tappet 1 is directed in the cam axis direction. An anti-rotation member main body 6 is provided.
[0025]
Next, the center tappet 1a and the side tappets 1b and 1c, and the locking member main body of the tappet 1 will be described in detail. First, the lock member will be described. In FIG. 2B, the center tappet 1a has a cam shaft line at a predetermined distance from the top plate sliding contact surface 1aa and a circular hole 8 substantially parallel to the top plate sliding contact surface 1aa. The side tappet 1s is also formed with a coaxial circular hole 10 extending from one side tappet 1b to the other side tappet 1c. Here, the circular hole 8 and the circular hole 10 have the same inner diameter, and the top plate sliding contact surface 1aa of the center tappet 1a and the top plate sliding contact surfaces 1bb and 1cc of the side tappets 1b and 1c are substantially the same height. The circular hole 8 and the circular hole 10 are arranged so as to have the same axis.
[0026]
A plunger 16, a sleeve A18, a spring 20, and a sleeve B22 are inserted into the circular hole 8 provided in the center tappet 1a. The sleeve B22 is press-fitted into the circular hole 8 in the vicinity of the side tappet 1b side end portion of the circular hole 8 provided in the center tappet 1a, and the side tappet 1b side end portion of the plunger 16 can reciprocate in the axial direction on the inner diameter portion thereof. Is contained. A spring 22 is provided on an end surface of the sleeve B22 (in the center direction of the center tappet 1a), one end of which is in contact with the other end, and the other end is in contact with a flange (not indicated) provided on the outer periphery of the plunger 16. The sleeve A18 is press-fitted in the vicinity of the end portion on the side tappet 1c side in the circular hole 8, and the inner end portion thereof is accommodated so that the end portion on the side tappet 1c side of the plunger 16 can reciprocate. The inner end face (center direction side of the center tappet 1a) is in contact with the flange of the plunger 16, thereby restricting the plunger 16 from protruding toward the side tappet 1c by the spring 22.
[0027]
A bush 24 that receives the plunger 16 is press-fitted into the circular hole 10 in the side tappet 1b. The center tappet 1a side of the bush 24 has the same inner diameter as the sleeve B22 so as to receive the plunger 16 when the plunger 16 moves into the side tappet 1b so as to engage and lock the center tappet 1a and the side tappet 1b. is doing. On the other hand, the inner diameter of the outer periphery side of the tappet of the bush 24 is made smaller than the inner diameter of the tappet center side, and the pin 26 is press-fitted, and the rotation prevention member main body that prevents the tappet 1 from rotating in the circumferential direction. The part 6 is fitted in a loose state. On the other hand, a substantially bottomed cylindrical sealing member 14 is press-fitted into the circular hole 10 in the side tappet 1c, and a piston 12 is accommodated inside the sealing member 14.
[0028]
As described above, the lock member according to the present invention includes the plunger 16, the sleeve A18, the spring 20, and the sleeve B22 provided on the center tappet 1a, the bush 24 provided on the side tappet 1b, and the side tappet 1c. The piston 12 and the seal member 14 are provided, and can be in a locked state in which the center tappet 1a and the side tappets 1b, 1c are engaged by an engine hydraulic pressure and an unlocked state in which these are separated. It has become. This hydraulic oil passes from the oil passage G of the cylinder head 2 described above with reference to FIG. 1 to the oil passage R1 of the tappet 1 shown in FIG. 2A, and then in the side tappet 1c of FIG. It is supplied to the hydraulic chamber PR from an opening R2 provided between the side end of the piston 12 and the piston 12.
[0029]
FIG. 3 is a diagram for explaining the locked and unlocked state of the center tappet 1a and the side tappets 1b and 1c in the tappet 1. The unlocked state is the locked state when the engine of FIG. (B) is during high-speed rotation of the engine. At the time of low speed rotation of (A), since the hydraulic pressure is set low, the piston 12 is prevented from moving in the direction of the center tappet 1a even if oil is supplied from the opening R2 to the hydraulic chamber PR. For this reason, the plunger 16 provided in the center tappet 1a does not move to the side tappet 1b side by the piston 12, and is also regulated by the sleeve A18 in the direction of the side tappet 1c. It seems to stop.
[0030]
That is, in this state, since the plunger 16 is not engaged with the bush 24, the high speed cam 4a having a high cam nose height in the cam 4 pushes down the center tappet 1a while slidingly rotating on the center tappet 1a. Since two lower springs 30 having a small spring constant are supported by a spring receiving member 32 (see FIG. 2 (C)), the center tappet 1a is shimmed by the action of the springs 30. The force that pushes down the valve (not shown) through 5 is absorbed, and the high-speed cam 4a does not contribute to the opening and closing of the valve. That is, in this unlocked state, the low speed cams 4b and 4c having a cam nose height lower than that of the high speed cam 4a act so as to push down the valve via the side tappets 1b and 1c.
[0031]
Next, at the time of high speed rotation of the engine of (B), high pressure oil is supplied to the hydraulic chamber PR from the opening R2 provided in the side tappet 1c. The piston 12 is pushed in the direction of the tappet 1 a, and the piston 12 overcomes the biasing force of the spring 20 to push the plunger 16 in the direction of the side tappet 1 b and engage with the bush 24.
[0032]
In this state, the center tappet 1a is engaged and locked with the side tappets 1b and 1c, so that the valve is lifted together with the side tappets 1b and 1c by the lift amount corresponding to the cam nose height of the high speed cam 4a. It is supposed to open in quantity.
[0033]
When the engine is changed from high speed to low speed, the hydraulic pressure decreases. Accordingly, the piston 12 loses the force to move the plunger 16 toward the side tappet 1b, and the spring 20 is regulated by the sleeve A18. To the predetermined position, and the valve can be returned to the open / closed state via the side tappets 1b and 1c by the low-speed cams 4b and 4c as described above.
[0034]
Subsequently, the rotation preventing member main body 6 that restricts the rotation of the tappet 1 in the circumferential direction will be described. As described above with reference to FIG. 2, the rotation preventing member main body 6 is loosely fitted to the pin 26 press-fitted on the outer peripheral side of the tappet of the bush 24 provided on the side tappet 1b. 1 to 3 shown so far, the anti-rotation member main body 6 protrudes in the same direction as the axis of the camshaft. However, as shown in FIG. If the guide groove 3a of the tappet guide hole 3 that accommodates this is offset with respect to the axis EE with respect to the axis EE of the camshaft, it is offset with respect to the camshaft. Since the thickness of the wall between tappet guide holes adjacent in the axis EE direction can be reduced, it is useful for reducing the size and weight of the engine.
[0035]
As a structure in which the rotation preventing member main body 6 is offset with respect to the camshaft axis EE at an angle θ, the hole 8 provided in the center tappet 1a as shown in FIG. The center axis of the hole 10 provided in the side tappets 1b and 1c is formed at an angle θ from the camshaft axis EE, and a lock member (not shown) is provided in them, and the bush 24 described above is pinned By fixing 26, the anti-rotation member main body 6 is also disposed at a position offset with an angle θ with respect to the camshaft axis EE, or as shown in FIG. 24 is not provided with a pin 26, and the pin 26 is integrally fixed to the outer peripheral wall of the side tappet 1b (or 1c) with an angle θ from the camshaft axis EE. Structure such as fitting the locking member body 6 around 26, it is possible to take various embodiments.
[0036]
Next, the relationship between the anti-rotation member main body 6 and the guide groove 3a that accommodates this and restricts the tappet 1 from rotating in the circumferential direction will be described with reference to FIG. 6A is a perspective view showing a state in which the anti-rotation member main body 6 is accommodated in the guide groove 3a having a substantially partial circular cross section. As can be seen, the anti-rotation member main body 6 has a sliding contact surface that is formed in a substantially vertically long and partially cylindrical shape along the guide groove 3a provided on the peripheral wall of the tappet guide hole 3 and is in sliding contact with the guide groove 3a. 6s, and a pin hole 6a into which the pin 26 is inserted at a right angle to the tappet sliding direction is formed slightly below the center in the vertical direction. The end of the pin 26 in the direction of the center of the tappet is press-fitted and fixed to the bush 24 as described with reference to FIG. 2, and the shaft of the pin 26 is provided at a position of a predetermined dimension from the tappet sliding contact surfaces 1aa and 1bb. It is what.
[0037]
FIG. 6B1 is a cross-sectional view taken along the line FF in FIG. 6A. As shown in FIG. 6B, the inner diameter of the pin hole 6a is slightly larger than the outer diameter of the pin 26. 26 is inserted into the pin hole 6a in a loose state. This is to cause the rotation preventing member main body 6 to swing as indicated by an arrow about the axis ZZ of the pin 26 in the guide groove 3a. That is, the rotation preventing member main body 6 reciprocates in the guide groove 3a while slightly swinging around the axis ZZ of the pin 26. As a result, the guide groove 3a comes into contact with the sliding contact surface 6s of the anti-rotation member main body 6 over a wide area, and the guide groove 3a is locally bent, finally has abnormal wear or seizure, or the anti-rotation member. Biting of the main body 6 into the guide groove 3a can be avoided.
[0038]
As another embodiment in which the anti-rotation member main body 6 swings as described above, although not particularly illustrated, the anti-rotation member main body 6 and the pin 26 are integrally formed, and the end portion on the tappet center side of the pin 26 is formed. May be inserted into the bush 24 in a loose state instead of being press-fitted. In other words, in this case, the inner diameter of the hole for receiving the pin 26 of the bush 24 is formed larger than the outer diameter of the pin 26, so that the rotation preventing member main body 6 is integrated with the pin 26 and swings around the axis of the pin 26. It reciprocates in the guide groove 3a while moving.
[0039]
In addition, as shown in FIGS. 1 to 3 described so far in the present embodiment, the cam-side end surface of the anti-rotation member main body 6 is a top plate sliding contact surface 1aa, 1bb of the tappet 1 that is in sliding contact with the cam 4. It is disposed at a position close to 1 cc. Specifically, as shown in FIG. 7, when the valve (not shown) is closed and the tappet 1 is in the uppermost position, the cam-side end surface H <b> 2 of the detent member main body 6 is the upper end surface of the tappet guide hole 3. Further, it can be projected to the cam side by, for example, several millimeters, and its structure is clearly different from that shown in FIG. 8 shown as the prior art. An effect can be produced.
[0040]
According to such a structure, since the cam is a part that has been ground with high accuracy, the reference surface H1 (with a predetermined distance L1 on the basis of the predetermined camshaft axial height position is used. In FIG. 7, the cylinder head 2 is machined to provide a reference surface H1). If the height dimension L2 between the reference surface H1 and the cam-side end face H2 of the anti-rotation member main body 6 is measured, the shaft center of the pin 26 is set to a position of a predetermined dimension with high accuracy from the tappet sliding surfaces 1aa and 1bb. Therefore, the height position of the tappet in the valve closed state is accurately obtained. In other words, by measuring the height of the cylinder head H1 with reference to the cam-side end surface H2 of the rotation stopper member main body 6, the tappet clearance, which is the distance between the valve and the tappet sliding surface in the valve closed state, is obtained. It becomes possible to measure and manage, and the work of measuring the tappet clearance by inserting the thickness gauge between the cam 4 and the top plate sliding contact surface 1aa, 1bb, or 1cc of the tappet 1 as in the prior art becomes unnecessary. It can be improved dramatically.
[0041]
As a structure for further drawing out the effect, as shown in FIG. 6 (B2), the cam-side end surface of the non-rotating member main body 6 may have an arc shape with a radius R from the center of the pin hole 6a. Accordingly, the reference height position of the cam-side end face H1 even when the anti-rotation member main body 6 protrudes from the tappet guide 3 at an angle swung with respect to the center line KK of the guide groove 3a. The tappet clearance can be adjusted and management accuracy can be improved.
[0042]
As described above, the present invention is a divided tappet in which one tappet is divided into a plurality of parts, and includes a lock mechanism for locking and unlocking the plurality of tappets therein, and has a plurality of cam nose heights. This is a valve operating system for an engine that uses a cam to vary the valve lift characteristics, and the engine can be reduced in size by offsetting a non-rotating member that restricts the rotation of the tappet in the circumferential direction from the axial direction of the camshaft. Further, durability can be improved by enabling the rotation preventing member to swing in the tappet sliding direction in the guide groove provided in the tappet guide hole. Furthermore, by disposing the cam-side end surface of the rotation preventing member at a position close to the sliding contact surface with the tappet cam, the tappet clearance can be easily measured and managed, and workability can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic view of a valve gear according to the present invention.
FIG. 2 is a detailed view of the valve gear according to the present invention.
FIG. 3 is a view showing a locking mechanism of a divided tappet.
FIG. 4 is a view showing an offset position of a rotation preventing member
FIG. 5 is a diagram showing details of a rotation preventing member
FIG. 6 is a view showing the swinging of the detent member.
FIG. 7 is a diagram for explaining the reference for the height position of the tappet.
FIG. 8 is a diagram showing a conventional technique.
[Explanation of symbols]
1 ... Tappet
1a ... Center tappet
1b, 1c, 1s ... side tappet
2 ... Cylinder head
3 ... Tappet guide hall
3a ... Guide groove
4 ... Cam
4a ... Center cam
4b, 4c ... side cam
6 ... Detent member body
12 ... Piston (lock mechanism)
16 ... Plunger (locking mechanism)
24 ... Bush (locking mechanism)
26 ... pin
H3: Tappet height position reference surface of the rotation stopper main body

Claims (1)

In a valve operating apparatus for an engine having a variable mechanism that changes a valve lift characteristic by including a lock mechanism that engages and disengages the tappet constituent member, wherein a tappet whose outer shape has a substantially cylindrical shape is formed by a plurality of tappet constituent members.
A single tappet is provided with a center cam and two side cams having different cam nose shapes from the center cam, and the tappet has a substantially rectangular center tappet extending in a direction perpendicular to the cam shaft and corresponding to each cam. A split tappet structure having side tappets on both sides, and the valves are driven with different characteristics by engaging and disengaging both tappets by the lock mechanism extending in the camshaft direction,
A tappet guide hole that has a guide groove extending in the sliding direction of the tappet and that accommodates the tappet is formed in the cylinder head, and the tappet is provided in the tappet to rotate in the circumferential direction. A detent member that restricts the insertion is inserted,
The anti-rotation member includes a main body portion having a sliding contact surface that is inserted into the guide groove and extends in a sliding direction, and a shaft portion that supports the main body portion on the tappet. It can swing around the axis of the shaft ,
The guide groove has a substantially partial circular shape in cross section when viewed from the tappet sliding direction, the main body portion has a partial cylindrical shape that is inserted into the guide groove, and the shaft portion is orthogonal to the main body portion. And is supported by being inserted into a hole provided in the tappet.
A valve operating apparatus for an engine, wherein the rotation preventing member is attached to and supported by a bush attached to a lock mechanism hole formed in one side tappet .

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