JP4212971B2 - Variable valve mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable valve mechanism for switching a lift amount or opening / closing timing of a valve in accordance with the rotational speed and load of the internal combustion engine by connecting and disconnecting a plurality of rocker arms in the valve mechanism of the internal combustion engine. .
[0002]
[Prior art]
Many of these types of variable valve mechanisms connect and disconnect a low-speed rocker arm that presses a valve and a high-speed rocker arm that does not directly press the valve. When the internal combustion engine is running at low speed, both rocker arms are disconnected, and the low-speed rocker arm that is swung by the low-speed cam opens and closes the valve. Further, when the internal combustion engine is at high speed, both arms are connected, and the low-speed rocker arm swings integrally with the high-speed rocker arm that swings by the high-speed cam to open and close the valve. Since the high-speed rocker arm at low speed is in a state of swinging, it is necessary to follow the high-speed cam up to the switching rotational speed in order to prevent the flapping and to perform smooth switching at the time of shifting to high speed. A mechanism for the follow-up is a lost motion mechanism, and a structure in which a biasing means such as a spring or hydraulic pressure is brought into contact with a high-speed rocker arm is generally used.
[0003]
[Problems to be solved by the invention]
However, the conventional lost motion mechanism has the following problems due to the location of the biasing member.
(1) The lost motion mechanism described in Patent Document 1 has a structure in which a cylindrical lifter urged by a coil spring provided in a cylinder head (engine body) is brought into contact with a high-speed rocker arm (third rocker arm). . In this mechanism, in order to attach the coil spring and the cylindrical lifter, it is necessary to design the cylinder head exclusively for the variable valve mechanism or to make a large modification.
(2) The lost motion mechanism described in Patent Document 2 has a structure in which a coil spring built in a rocker arm is brought into contact with a cam follower provided slidably on the rocker arm. In this mechanism, there is a problem that the inertia mass of the rocker arm is increased by the amount of the coil spring or the like, and in order to reduce the increase, it is necessary to reduce the size and weight of the coil spring, so that the spring design is difficult.
[0004]
[Patent Document 1]
JP-A-2-78718
[Patent Document 2]
JP-A-10-196335
[0005]
Therefore, an object of the present invention is to configure the lost motion mechanism using a torsion coil spring extrapolated to the rocker shaft, so that it is not necessary to design or modify the cylinder head exclusively for the lost motion mechanism. An object of the present invention is to provide a variable valve mechanism capable of providing a sufficient safety factor for spring design in the lost motion mechanism and increasing the degree of freedom in design because the influence of the lost motion mechanism on the increase in inertia mass of the rocker arm is small. .
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the variable valve mechanism of the present invention includes a first rocker arm that contacts the first cam and presses the valve, and a second rocker arm that contacts the second cam and does not press the valve directly. The rocker shaft is swingably attached, the operation is switched by connecting and disconnecting the first rocker arm and the second rocker arm, and the second rocker arm that is swung when the first rocker arm and the second rocker arm are disconnected is lost. In the variable valve mechanism that follows the second cam by the motion mechanism, the lost motion mechanism is a structure that urges the second rocker arm by a torsion coil spring that is extrapolated to the rocker shaft. One end of the torsion coil spring is fixed to the second rocker arm, the other end of the torsion coil spring is fixed to the stop member attached to the rocker shaft, and the stop position for stopping the other end of the torsion coil spring is the rotation direction around the rocker shaft. Using an adjustable stop member that can adjust the spring load of the torsion coil spring by adjusting the position to It is characterized by that.
[0007]
Here, the first rocker arm and the second rocker arm are not limited to a combination of specific uses, and a combination of a low speed rocker arm and a high speed rocker arm, a combination of a resting rocker arm and a non-resting rocker arm, and the like can be exemplified.
[0008]
G The method of stopping one end of the torsion coil spring to the second rocker arm is not particularly limited, but the one end is brought into contact with the stopper provided on the second rocker arm so that the extension of the torsion coil spring in the torsional direction is restricted. The aspect stopped by this, and the aspect stopped by inserting one end into the stop hole provided in the 2nd rocker arm can be illustrated. The method for stopping the other end of the torsion coil spring to the stop member is not particularly limited. Similarly, the other end of the torsion coil spring is applied to the stop portion provided on the stop member so that the extension of the torsion coil spring in the torsional direction is restricted. A mode of stopping by touching and a mode of stopping by inserting the other end into a stop hole provided in the stop member can be exemplified.
[0009]
Also , Key Although it does not specifically limit as a node type stop member, The following structure can be illustrated.
{1} The stop position can be adjusted by rotating and adjusting the stop member main body externally attached to the rocker shaft. After the rotation adjustment, the stop member main body is fastened so as not to rotate to the rocker shaft. Adjustable stop member made possible.
{2} Only a stop portion for stopping the other end of the torsion coil spring is provided in the rotation direction around the rocker shaft so that the other end of the torsion coil spring can be adjusted with respect to the stop member main body mounted so as not to rotate on the rocker shaft. An adjustable stop member that allows the position to be adjusted. In this case, means for attaching the stopper member body to the rocker shaft so as not to rotate is not particularly limited, but means for fastening the stopper member body to the rocker shaft so as not to rotate or the stopper member body separately from the rocker shaft. A means for extrapolating to two shafts can be exemplified.
[0010]
The wire of the torsion coil spring is not particularly limited and may be a round wire, but it is preferable to use a wire in which adjacent surfaces of the windings form a substantially flat surface.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a variable valve mechanism embodying the present invention will be described with reference to FIGS. In this example, a variable valve mechanism of two cylinders for two cylinders and only on the intake valve side is illustrated and described. However, this number of stations can be appropriately changed according to the number of cylinders and the cylinder arrangement of the internal combustion engine. The variable valve mechanism can also be implemented on the exhaust valve (denoted by reference numeral 90 only in FIG. 1) side.
[0012]
As shown in FIGS. 1 to 4, a right support 3, a center support 4, and a left support 5 are respectively attached by bolts 6 at three positions of a cylinder head 2 that sandwiches two cylinders 1. The opposed faces of the right support 3 and the left support 5 are provided with mounting holes 7 that are horizontally oriented and bottomed, and the central support 4 is provided with mounting holes 7 that penetrate laterally. The rocker shaft 10 is supported by the tubular rocker shafts 10 being passed through the mounting holes 7 and the bolts 6 being passed through the holes penetrating the rocker shaft 10 in the direction perpendicular to the axis. Of the rocker shaft 10 corresponding to each cylinder, a first region between the right support 3 and the center support 4 and a second region between the center support 4 and the left support 5 are respectively a non-variable rocker arm 11 and a first rocker arm. A low speed rocker arm 12 and a high speed rocker arm 13 as a second rocker arm are arranged, and a lost motion mechanism 70 of the high speed rocker arm 13 is arranged. Each arm 11, 12, 13 is pivotally mounted by being able to swing when the rocker shaft 10 is inserted into the insertion hole 14 at the approximate center in the length direction.
[0013]
In detail, in the first region, the non-variable rocker arm 11 is disposed substantially in contact with the left side of the right support 3, the low-speed rocker arm 12 is disposed in contact with the right side of the center support 4, and The high-speed rocker arm 13 is disposed substantially in contact with the right side of the low-speed rocker arm 12, and the lost motion mechanism 70 is disposed in the remaining area between the high-speed rocker arm 13 and the non-variable rocker arm 11. Also in the second region, if the right support 3 is replaced with the central support 4 and the central support 4 is replaced with the left support 5, the rocker arms 11, 12, 13 and the lost motion mechanism 70 are similarly arranged.
[0014]
A roller 15 that abuts on a cam, which will be described later, is rotatably attached to the rear end of each rocker arm 11, 12, 13. Specifically, as shown in FIGS. 5A and 5B, the rollers 15 are sandwiched between the both-side forks 20 processed at the rear ends of the rocker arms 11, 12, and 13, and the both-side forks 20 are caulked. The roller 15 is attached to the shaft 21 (known shaft attachment structure). In addition, as shown in FIG. 5 (c), as a novel shaft mounting structure, one-side fork 22 machined at the rear end of each rocker arm 11, 12, 13 (particularly suitable for low-speed rocker arm 12 with low input load). Further, the roller 15 may be attached to the shaft 23 so that the roller 15 is sandwiched between the flange 23a of the shaft 23 that is caulked and secured thereto. Further, as shown in FIG. 5D, the roller 15 is sandwiched between the one-side fork 22 and the flange 25a of the outer shaft 25 that is applied thereto and is caulked by the inner shaft 24, so that the outer shaft The roller 15 may be attached to the shaft 25. According to the shaft mounting structure to these one-side forks 22, space saving can be achieved. A pressing body 26 that presses the upper end of the valve 9 is provided at the distal ends of the non-variable rocker arm 11 and the low-speed rocker arm 12 so that the protrusion amount can be adjusted by a screw mechanism. Since the high-speed rocker arm 13 does not directly press the valve 9, it does not extend to the tip side and is not provided with a pressing body, but a stopper 16 that is pressed by one end 72 of a torsion coil spring 71 described later is provided on the right side surface. Projected to
[0015]
As shown in FIGS. 4 to 6, a camshaft 60 is provided at a position slightly away from the rocker shaft 10 toward the cylinder, and is driven to rotate. A non-variable cam 61 having a cam nose with an arbitrary working angle and lift amount and a working angle as the first cam at positions corresponding to the rocker arms 11, 12, 13 in the first region and the second region of the camshaft 60. A low-speed cam 62 having a cam nose with a small lift amount and a high-speed cam 63 having a working angle and a cam nose with a large lift amount as a second cam are formed. The non-variable cam 61 contacts the roller 15 of the non-variable rocker arm 11, the low-speed cam 62 contacts the roller 15 of the low-speed rocker arm 12, and the high-speed cam 63 contacts the roller 15 of the high-speed rocker arm 13.
[0016]
A switching mechanism for connecting the low-speed rocker arm 12 and the high-speed rocker arm 13 so as to be able to swing integrally, and to separate and swing separately, is configured as follows. Projections 8 are integrally projected on the rear side of the supports 3, 4, 5 (corresponding to the base end side of the rocker arm). As shown in FIG. 7 and the like, a cylinder hole 30 is recessed in the middle of the right side surface of each protrusion 8 of the center support 4 and the left support 5, and a piston pin 31 is slidably accommodated in the cylinder hole 30. ing. A pin hole 32 is provided in the protrusion 17 provided on the base end side of the low-speed rocker arm 12 in the first region and the second region, and a switching pin 33 is slidably received in the pin hole 32. . The protrusion 18 provided on the base end side of the high-speed rocker arm 13 has a pin hole 34 recessed from the left side surface, and a cup-shaped pusher pin 35 is slidably received in the pin hole 34 and a coil spring 36. The coil spring 36 biases the pusher pin 35 toward the switching pin 33. The cylinder hole 30, the pin hole 32, and the pin hole 34 are provided so that their axes coincide with each other when the rocker arms 12 and 13 are to be connected at a high speed of the internal combustion engine. Both rocker arms 12 and 13 are connected when straddling 32 and 34.
[0017]
The hydraulic path for the switching mechanism will be described. The right support 3 has an oil supply port 40 formed on the mounting surface to the cylinder head 2 and an oil passage 41 from the oil supply port 40 toward the protrusion 8. A mounting hole 49 communicating with the oil passage 41 is formed at the left end of the protrusion 8. The oil supply port 40 is connected to a hydraulic pump through an oil passage in the cylinder head and further via a switching valve. The central support 4 is formed with an oil passage 43 that penetrates the central support 4 and communicates with the cylinder hole 30, and communicates with the oil passage 43 at the right end and the left end of the protrusion 8. A mounting hole 49 is formed. An oil passage 45 communicating with the cylinder hole 30 is formed in the left support 5, and a mounting hole 49 communicating with the oil passage 45 is formed at the tip of the right side surface of the protrusion 8. A first oil supply pipe 42 is attached between the right support 3 and the center support 4 by inserting both ends of the first oil supply pipe 42 into the mounting holes 49 of both supports 3 and 4. Between them, the second oil supply pipe 44 is attached by inserting both ends thereof into the attachment holes 49 of the supports 4 and 5. Accordingly, a hydraulic path of the oil supply port 40 → the oil path 41 → the first oil supply pipe 42 → the oil path 43 → the second oil supply pipe 44 → the oil path 45 is formed, and the cylinder hole of the central support 4 is formed from the oil path 43. 30 and the oil for switching are supplied from the oil passage 45 to the cylinder hole 30 of the left support 5. The oil supply pipes 42 and 44 and the rocker shaft 10 are arranged in parallel.
[0018]
On the other hand, a hydraulic path for lubrication between the rocker shaft 10 and the insertion holes 14 of the rocker arms 11, 12, 13 will be described. As shown in FIGS. 3 to 6, the central support 4 is connected to the cylinder head 2. An oil supply port 50 is formed on the attachment surface, and the oil supply port 50 opens in the attachment hole 7. An oil entry hole 51 is provided in the pipe wall of the rocker shaft 10 in the mounting hole 7, and an oil discharge hole 52 is provided in the pipe wall of the rocker shaft 10 in the insertion hole 14 of each rocker arm 11, 12, 13. Has been. Accordingly, a hydraulic path of the oil supply port 50 → the oil inlet hole 51 → the inside of the rocker shaft 10 → the oil outlet hole 52 is formed, and the lubricating oil is provided between the oil outlet hole 52 and the rocker shaft 10 and the insertion hole 14. Is to be supplied. The lubricating hydraulic path is independent of the switching hydraulic path.
[0019]
Next, the lost motion mechanism 70 that causes the high-speed rocker arm 13 to follow the high-speed cam 63 is between the high-speed rocker arm 13 and the non-variable rocker arm 11 in the first region and the second region of the rocker shaft 10 as described above. The remaining areas are arranged as follows. In the remaining area, a coiled torsion coil spring 71 is inserted concentrically together with a spring frame 74 that holds the torsion coil spring 71 on the left side adjacent to the high-speed rocker arm 13 so as to be rotatable. An adjustable stop member 78 that stops the other end of the torsion coil spring 71 and adjusts the spring load is rotatably inserted on the right side adjacent to the non-variable rocker arm 11 and fastened after the rotation is adjusted. .
[0020]
The torsion coil spring 71 is formed by winding a wire in a coil shape a plurality of times, and one end 72 and the other end 73 project radially. The wire may be a round wire, but as shown in FIG. 8C, in this example, a deformed wire in which the adjacent surfaces of the windings form a substantially flat surface is used, and the specific cross-sectional dimension is 3 1 mm (winding radius side) × 1.9 mm (spring long side). By using this wire, it is possible to reduce the stress, save space, and prevent the collapse during the spring operation. The spring frame 74 includes a pair of ring frame portions 75 that cover both end faces of the torsion coil spring 71 and a connecting portion 76 that connects both the ring frame portions 75. The protruding portion of one ring frame portion 75 is described below. A hole 77 for inserting the stopper is formed. Then, the torsion coil spring 71 is housed in the spring frame 74 and the elongation in the spring length direction is restricted, and the torsion coil spring 71 and the ring frame portion 75 are extrapolated to the rocker shaft 10. The one end 72 of the torsion coil spring 71 is stopped by coming into contact with the stopper 16 of the high-speed rocker arm 13 so that the extension of the torsion coil spring 71 in the torsional direction is restricted.
[0021]
The adjustable stop member 78 includes a stop member main body 79 having a cut at one portion of the ring, and a fastening member screwed into the stop member main body 79 so that the stop member main body 79 can be tightened by approaching both sides of the cut. It comprises an attaching screw 80 and a protruding stopper 81 protruding from the left side surface of the stopper member body 79. The stop member body 79 is extrapolated to the rocker shaft 10, the stop portion 81 is inserted into the hole 77, and the other end 73 of the torsion coil spring 71 is restricted from extending in the torsional direction of the torsion coil spring 71 with respect to the stop portion 81. 8A and 8B, when the stop member main body 79 is manually rotated and adjusted, the stop position of the other end 73 by the stop portion 81 is around the rocker shaft 10 as shown in FIGS. The position is adjusted in the rotational direction, and the torsion coil spring 71 is compressed in the torsional direction. By the compression adjustment by the rotation adjustment, the spring load of the torsion coil spring 71 (the load at which the one end 72 presses the stopper 16 of the high-speed rocker arm 13) is adjusted. Thus, it is fastened to the rocker shaft 10 so as not to rotate. Since one end 72 of the torsion coil spring 71 thus adjusted in spring load presses the stopper 16 of the high speed rocker arm 13 and presses the roller 15 against the high speed cam 63, the high speed rocker arm is also swung during the low speed rotation described later. 13 can follow the high-speed cam 63.
[0022]
The variable valve mechanism configured as described above operates as follows. The oil supply port 50 is always supplied with oil, and the oil supply port 50, the oil inlet hole 51, the rocker shaft 10, the oil outlet hole 52, and the oil outlet hole 52 to the rocker shaft 10 and the rocker arms 11, 12, 13. Lubricating oil is supplied between the insertion hole 14. The lubrication lubrication may be a continuous lubrication system or an intermittent lubrication system, and even if the lubrication system is an intermittent lubrication system, there is no concern that the hydraulic pulsation at that time will affect a switching hydraulic path described later. This is because the switching hydraulic path and the lubricating hydraulic path are independent. The non-variable rocker arm 11 is always swung by the non-variable cam 61 regardless of the rotational speed of the internal combustion engine described below, and the valve 9 pressed against the non-variable rocker arm 11 can be arbitrarily changed according to the cam shape of the non-variable cam 61. Opened and closed with variable timing and lift amount.
[0023]
Now, when the internal combustion engine rotates at a low speed, the oil supply to the oil supply port 40 is stopped and the piston pin 31 is de-energized as shown in FIG. For this reason, since the coil spring 36 pushes the switching pin 33 and the piston pin 31 via the pusher pin 35, the switching pin 33 stops at a position not straddling the low speed rocker arm 12 and the high speed rocker arm 13. The connection is disconnected. Accordingly, the low-speed rocker arm 12 is swung independently by the low-speed cam 62, and the valve 9 is opened and closed at the low-speed timing and the lift amount according to the cam shape of the low-speed cam 62. At this time, the high-speed rocker arm 13 is swung by the high-speed cam 63, but the lost motion mechanism 70 presses the roller 15 of the high-speed rocker arm 13 against the high-speed cam 63 to follow, so that the high-speed rocker arm 13 is prevented from flapping. In addition, smooth switching can be performed at the time of shifting to high-speed rotation described later.
[0024]
In this embodiment, since the torsion coil spring 71 extrapolated to the rocker shaft 10 is used as the lost motion mechanism 70, the variable valve mechanism including the lost motion mechanism 70 can be modularized. In addition, it is not necessary to design or modify the cylinder head 2 exclusively for the lost motion mechanism, and the internal combustion engine that is currently mass-produced can be made variable without significant layout change. In addition, since the influence of the lost motion mechanism on the increase in the inertial mass of the high-speed rocker arm 13 is small, a sufficient safety factor can be expected for the spring design in the lost motion mechanism 70 and the degree of freedom in design is increased. Moreover, since the spring load of the torsion coil spring 71 can be adjusted, an optimum load can be applied, and the problem of increased friction when the roller 15 is pressed against the high-speed cam 63 with a load more than necessary can be solved. Further, by performing the adjustment, it becomes possible to suppress the dimensional accuracy requirement of each component such as a spring.
[0025]
Next, when the internal combustion engine is at a speed higher than the switching rotational speed, the oil supply port 40 is supplied with oil, and the oil supply port 40 → the oil passage 41 → the first oil supply pipe 42 → the oil passage 43 → the second oil supply pipe 44 → The oil for switching is supplied from the oil passage 43 to the cylinder hole 30 of the central support 4 and from the oil passage 45 to the cylinder hole 30 of the left support 5 through the hydraulic passage of the oil passage 45. As described above, this switching hydraulic path is separated and independent from the lubricating hydraulic path and is not affected by leakage or pulsation due to lubrication unlike the conventional hydraulic path combined type. It is easy to switch and hold. In addition, there is an advantage that it is not necessary to use an oil pump having a higher discharge capacity than necessary, and the oil pressure required for switching can be secured even in a low rotation range where the discharge capacity of the oil pump is not so high. In addition, since switching oil is supplied by a hydraulic path using the oil supply pipes 42 and 44 installed between the supports, the switching oil hole is made narrower as in the conventional independent type of hydraulic path in the rocker shaft, and the switching responsiveness. There is no concern that it will deteriorate, and it is easy to manufacture. When the switching oil is supplied to the cylinder hole 30 in this way, as shown in FIG. 7B, the piston pin 31 is urged, and the switching pin 33 and the pusher pin 35 are pushed against the urging force of the coil spring 36. Therefore, the switching pin 33 straddles the low-speed rocker arm 12 and the high-speed rocker arm 13, and the two rocker arms 12 and 13 are connected. Accordingly, the high-speed rocker arm 13 is swung by the high-speed cam 63, the low-speed rocker arm 12 is also swung together with the high-speed rocker arm 13, and the valve 9 is driven at a high-speed timing and lift amount according to the cam shape of the high-speed cam 63. Open and close. At this time, the low speed cam 62 rotates idly without affecting the swing of the low speed rocker arm 12.
[0026]
Next, FIGS. 9 to 11 show modified examples of the lost motion mechanism 70. In this modified example, the adjustable stop member 83 is extrapolated to the rocker shaft 10 by extrapolating the rocker shaft 10 and the first oil supply pipe 42 (or the second oil supply pipe 44) as another shaft. A stop member body 84 that is mounted so as not to rotate, a stop portion 85 that contacts and stops the other end 73 of the torsion coil spring 71, and the stop portion 85 rotates about the rocker shaft 10 with respect to the stop member body 84. It comprises an adjustment screw 86 that allows displacement adjustment in the direction. The stopper member body 84 is formed with a slit 87 that continuously extends from the hole through which the rocker shaft 10 is passed and intersects the adjustment screw 86. The slit 87 is narrowed by the adjustment screw 86, so that the stopper member body 84 is rocker. It is fastened to the shaft 10 to some extent. A guide gap 88 that guides the displacement of the stopper 85 is formed on the stopper member main body 84 and the protruding portion of one ring frame 75 of the spring frame 74.
[0027]
According to this modified example, as shown in FIGS. 11A and 11B, the other end 73 by the stop portion 85 is simply adjusted by screwing the adjustment screw 86 without rotating the stop member main body 84. Can be displaced in the rotational direction around the rocker shaft 10, and the torsion coil spring 71 is compressed in the torsional direction. Since the biasing force of the torsion coil spring 71 is adjusted by the compression adjustment by this displacement adjustment, the adjustment work is easy.
[0028]
In addition, this invention is not limited to the structure of the said embodiment, In the range which does not deviate from the meaning of invention, it can change suitably and can be actualized.
[0029]
【The invention's effect】
As described above in detail, according to the variable valve mechanism according to the present invention, the cylinder head is designed exclusively for the lost motion mechanism by configuring the lost motion mechanism using the torsion coil spring extrapolated to the rocker shaft. The effect of increasing the inertial mass of the rocker arm due to the lost motion mechanism is small, so it is possible to expect a sufficient safety factor for the spring design in the lost motion mechanism. Play.
[Brief description of the drawings]
FIG. 1 is a perspective view of a variable valve mechanism according to an embodiment of the present invention.
FIG. 2 is a plan view of the variable valve mechanism.
FIG. 3 is a bottom view of the variable valve mechanism.
FIG. 4 is an exploded perspective view of the variable valve mechanism.
5A is a cross-sectional view taken along the line VV of FIG. 2, and FIGS. 5B, 5C, and 4D are cross-sectional views illustrating a roller mounting structure.
6 is a cross-sectional view taken along line VI-VI in FIG.
7A and 7B show a switching mechanism of the variable valve mechanism, wherein FIG. 7A is a cross-sectional view at low speed, and FIG. 7B is a cross-sectional view at high speed.
FIG. 8 is a sectional view of a lost motion mechanism of the variable valve mechanism.
FIG. 9 is a perspective view of a modified example of a lost motion mechanism.
FIG. 10 is an exploded perspective view of main parts of the modified example.
FIG. 11 is a sectional view of the modified example.
[Explanation of symbols]
3 Right support
4 Central support
5 Left support
10 Rocker shaft
11 Non-changeable rocker arm
12 Rocker arm for low speed as the first rocker arm
13 Rocker arm for high speed as the second rocker arm
33 switching pin
42 First oil supply pipe
44 Second oil supply pipe
70 Lost motion mechanism
71 Torsion coil spring
72 one end
73 The other end
78 Adjustable stop
79 Stopping member body
80 Tightening screw

Claims (6)

A first rocker arm that contacts the first cam and presses the valve and a second rocker arm that contacts the second cam and does not press the valve directly are arranged side by side on the rocker shaft so as to be swingable. In the variable valve mechanism that switches the operation by connecting and disconnecting the rocker arm, and causing the second rocker arm to swing idle when the first rocker arm and the second rocker arm are disconnected to follow the second cam by the lost motion mechanism,
Lost motion mechanism Ri structures der for urging the second rocker arm by a torsion coil spring which is extrapolated to the rocker shaft, stop the one end of the torsion coil spring to the second rocker arm, stop member attached to the other end of the torsion coil spring to the rocker shaft Stop
As the stop member, an adjustable stop member is used, which adjusts the spring load of the torsion coil spring by adjusting the stop position for stopping the other end of the torsion coil spring in the rotational direction around the rocker shaft. A variable valve mechanism. The adjustable stop member can adjust the stop position by rotating and adjusting the stop member main body that is pivotally attached to the rocker shaft, so that the stop member main body does not rotate to the rocker shaft after the rotation adjustment. The variable valve mechanism according to claim 1 , wherein the variable valve mechanism is capable of being fastened to. An adjustable stop member is provided with a stop portion for stopping the other end of the torsion coil spring with respect to the stop member main body that is mounted so as not to rotate on the rocker shaft so that the displacement can be adjusted in the rotation direction around the rocker shaft. variable valve mechanism according to claim 1, wherein is obtained by allowing adjustment position of the stop position by adjusting. 4. The variable valve mechanism according to claim 3 , wherein the stopper member main body is fixed to the rocker shaft so as not to rotate in order to attach the stopper member main body to the rocker shaft so as not to rotate. The variable valve mechanism according to claim 3 , wherein the stopper member body is extrapolated into two parts, a rocker shaft and another shaft, in order to attach the stopper member body to the rocker shaft so as not to rotate. The variable valve mechanism according to any one of claims 1 to 5 , wherein the torsion coil spring uses a wire material in which adjacent surfaces of the windings form a substantially flat surface.

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