JPH05231116A - Valve system for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a valve system for an internal combustion engine where an adjusting range of a valve timing can be sufficiently secured, and the valve timing can be varied continuously while achieving miniaturization of a cylinder head as a whole, application to a multiple cylinder internal combustion engine can be easy. CONSTITUTION:A valve system is provided with a transmitting member 30 interposed between a cam surface of a cam 14b of a camshaft 14 and a slipper surface 19b of a rocker arm 19, for transmitting a cam lift to a rocker arm, where a point in contact with the cam surface, a point in contact with the slipper surface and the center of rotation of the camshaft are kept to be almost aligned at the time of oscillation on the center of rotation of the camshaft; a guide bridge 40 having a guide groove 40a for holding the transmitting member 30 in such a manner as to be displaced only in the diametrical direction of the camshaft and oscillatably supported by the camshaft; and a driving mechanism 50 for oscillating the guide bridge 40 according to the operating condition of an internal combustion engine. A valve timing variable mechanism 60 comprises the member 30, bridge 40, and mechanism 50.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve operating system for an internal combustion engine in which a variable valve timing mechanism is arranged in at least one of an intake valve operating mechanism and an exhaust valve operating mechanism.

[0002]

2. Description of the Related Art Conventionally, as a valve operating device for such an internal combustion engine, for example, a rocker arm which is swung by a rotating cam, and a swing center portion of the rocker arm is rotated about a rotation center portion of the cam. The rotation mechanism that allows the rocker arm to swing freely about one end between the tip of the rocker arm and the valve stem of the intake / exhaust valve, and the contact portion with which the tip of the rocker arm abuts is the center of rotation of the cam. There is known a rocker arm guide member which is an arc-shaped guide portion centered on the above portion (Japanese Patent Laid-Open No. 64-53009).

Further, as a conventional valve train for an internal combustion engine,
Each cam shaft is provided with two cam shafts driven by a pair of cam gears that mesh with a common idler gear, and a rocker arm that abuts on a cam provided on each cam shaft and swings around a fulcrum. It is attached to the tip of a pair of camshaft supporting arms pivotally supported coaxially with the shaft, and the camshaft supporting arms are rocked by a supporting arm drive mechanism according to the change in the rotational speed of the internal combustion engine, and the phase angle of the cam and the rocker arm It is known that the vibrating timing of the intake valve and the exhaust valve and the valve lift are changed by changing the lever ratio (Japanese Patent Laid-Open No. Hei 2).
-286815).

[0004]

However, in the former prior art described above, since the large rocker arm as a whole is rocked, the rocking range thereof is limited,
This limits the adjustment range of the valve lift. Therefore, there is a problem in that the entire cylinder head becomes large in size in order to secure a sufficient swing range.

Further, the latter prior art described above has the following problems.

Since the camshaft itself is rocked, it is necessary to provide a rocking shaft for the camshaft supporting arm. The rocking shaft is installed at the positions of the driven gear and idler gear of the cam and the slipper surface of the rocker arm. Considering the shape, etc., it is located just above the combustion chamber, and its installation is difficult. Especially when it is applied to a multi-cylinder internal combustion engine, it is quite difficult to install the oscillating shaft over all the cylinders just above the combustion chamber.

Considering the positions of the driven gear and idler gear of the cam, the shape of the slipper surface of the rocker arm, and the like, the length of the camshaft support arm becomes long, and it is attempted to secure a sufficient swing angle of this support arm. , The whole Sirida head becomes large.

[0008] Since the cam camshaft is oscillated while the cam gear of the camshaft meshes with the idler gear and is rotating, the driving force for oscillating the camshaft becomes very large.

The present invention has been made by paying attention to such a conventional problem, and it is possible to secure a sufficient valve timing adjustment range while continuously downsizing the cylinder head and to continuously control the valve timing. An object of the present invention is to provide a valve operating device for an internal combustion engine that can be changed, facilitates application to a multi-cylinder internal combustion engine, and reduces the driving force.

[0010]

In order to achieve the above-mentioned object, the present invention comprises a camshaft disposed on the upper part of a cylinder head, and a rocker arm that abuts on the cam of the camshaft and swings around a fulcrum. In a valve operating system for an internal combustion engine including an intake valve operating mechanism and an exhaust valve operating mechanism, at least one of the valve operating mechanisms includes a cam surface of the cam and a slipper surface of the rocker arm. A member for transmitting a cam lift to a rocker arm, which is disposed between the contact points with the cam surface, the contact point with the slipper surface, and the contact point of the cam shaft at least at the time of swinging around the rotation center of the cam shaft. A transmission member having a shape in which the center of rotation is always located on a substantially straight line, and a gas holding member for holding the transmission member so that it can be displaced only in the radial direction of the camshaft. A variable valve timing mechanism having a swing member that has a swing portion and is swingably supported by a camshaft, and a drive mechanism that swings the swing member according to the operating state of the internal combustion engine is provided. (Claim 1).

Preferably, the transmission member has a shaft portion whose both ends are held by guide portions of the swing member, and is rotatably supported by the shaft portion, and is arranged between the cam surface and the slipper surface. And a rotating body that has been rotated (claim 2).

Further, preferably, the rotating body is a roller (claim 5).

[0013]

In the above valve operating system, when the transmission member is swung about the rotation center of the cam shaft, the lever ratio of the rocker arm is changed according to the swing angle, and the valve timing of the intake valve and / or the exhaust valve is changed. Changes. The transmission member is a member that transmits the cam lift to the rocker arm and is small and lightweight, so that a driving force for swinging the rocker arm can be small. Further, it is not necessary to specially provide the swing shaft of the transmission member.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

In the description of each embodiment, the same members are designated by the same reference numerals, and the duplicated description will be omitted.

1 to 5 show a valve operating system for an internal combustion engine according to a first embodiment of the present invention. This first embodiment is
1 shows a valve train applied to a single overhead camshaft type multi-cylinder internal combustion engine.

As shown in FIG. 1, the valve operating system 1 is arranged in a valve operating chamber 4 defined by a cylinder head 2 and a cylinder head cover 3 which are joined to the upper surface of a cylinder block (not shown). .. The valve operating system 1 includes an intake valve operating mechanism 5 and an exhaust valve operating mechanism 6.

As shown in FIG. 1, the cylinder head 2 is provided with a pair of intake ports 8 and a pair of exhaust ports 9 in the portion forming the ceiling surface of the combustion chamber 7 of each cylinder. Each intake port 8 is connected to the intake port 10 and each exhaust port 9
Is connected to the exhaust port 11. In a portion of the cylinder head 2 corresponding to each cylinder, a pair of intake valves 12 that open and close each intake port 8 and a pair of exhaust valves 1 that open and close each exhaust port 9 are provided.
3 is provided. Each intake valve 12 and each exhaust valve 13
Are urged in the valve closing direction by valve springs 12a and 13a, respectively.

Further, the cylinder head 2 has a structure shown in FIG.
As shown in FIG. 4, the cam journal portion 200 is integrally formed. A cam holder 210 is arranged on the upper end surface 200a of the cam journal portion 200, and the cam holder 210 is fastened to the cam journal portion 200 by two bolts 220 for each cam holder 210 (see FIGS. 2 and 5). ). A semicircular recess 200b that supports the lower half of the shaft outer peripheral surface (journal surface) 14c of the camshaft 14 is provided at the upper end of the cam journal portion 200.
However, at the lower end of the cam holder 210, the camshaft 14
A semicircular recess 210a that supports the upper half of the shaft outer peripheral surface 14c is formed (see FIG. 3). As described above, the camshaft 14 has the shaft outer peripheral surface 14 c and the recess 200 b of the cam journal 200 and the cam holder 210.
It is rotatably supported by being sandwiched by the recess 210a.

As shown in FIGS. 1, 3 and 5, the exhaust valve operating mechanism 6 includes two exhaust valve cams 14a provided on the camshaft 14 for each cylinder and each cylinder. The rocker arm 15 is provided for each two rocker arms 15. Each rocker arm 15 is rotatably supported by a support shaft 16 provided on the cam holder 210. A cam follower 17 that comes into contact with the exhaust valve cam 14a is rotatably supported at one end of each rocker arm 15, and a contact member 18 is held at the other end so that its position can be adjusted. The lower end of each contact member 18 is the upper end 13 of each exhaust valve 13.
It is in contact with b. As a result, when the camshaft 14 rotates at half the rotation speed of the crankshaft 14 in conjunction with the rotation of the crankshaft of the internal combustion engine, the cam lift of each exhaust valve cam 14 a causes each exhaust valve to pass through each rocker arm 15. 13 and the exhaust valves 13 are opened and closed.

On the other hand, the valve operating mechanism 5 for the intake valve is shown in FIGS.
Further, as shown in FIG. 5, the intake valve cams 14b are provided for each cylinder, and two rocker arms 19 are provided for each cylinder. Each rocker arm 19
Is swingably supported by a support shaft 20 provided on the cam holder 210. One arm 1 of each rocker arm 19
The lower surface 19b of 9a is a circular slipper surface,
A contact member 21 is held at the end of the other arm 19c so that its position can be adjusted. The lower end of each contact member 21 is in contact with the upper end 12b of each intake valve 12.

Further, the intake valve actuating mechanism 5 has the structure shown in FIGS.
As shown in FIGS. 3 and 5, the intake valve cams 14b are provided.
Between the cam surface of the rocker arm 19 and the slipper surface 19b of each rocker arm 19, which is a member for transmitting the cam lift to the rocker arm 19, and each transfer member 30 can be displaced only in the radial direction of the camshaft 14. A guide bridge (swing member) 40 that has a guide groove (guide portion) 40a held on the
A vibration timing variable mechanism 60 having a drive mechanism 50 that swings the guide bridge 40 according to the operating state of the internal combustion engine is provided.

As shown in FIGS. 1, 3 and 5, each transmission member 30 has a roller inner shaft (shaft portion) 31 whose both ends are held in the guide groove 40a so as to be displaceable only in the radial direction. And rotatably supported on the shaft 31 via a needle bearing 32, and the intake valve cam 1
A roller outer for cam follower (hereinafter, simply referred to as a first rotating body) 33 that abuts on the cam surface of 4b, and is arranged on both sides of the first rotating body 33. And a pair of rocker arm roller outers (hereinafter, simply referred to as a second rotating body) 35 that are rotatably supported. Each of the second rotating bodies 35 is in contact with the slipper surfaces 19b of the rocker arms 19 on both sides of the first rotating body 33.

As shown in FIGS. 2 to 4, the guide bridge 40 extends over all the cylinders that share one camshaft so as to hold the two transmission members 30 arranged for each cylinder. It has an integrally extending shape and is swingably supported by the shaft portion outer peripheral surface 14c of the cam shaft 14 at two locations inside the cam holder 210 and the cam journal portion 200 for each cylinder. For example, in an in-line four-cylinder internal combustion engine, the guide bridge 20 has an integral shape that extends over the entire four cylinders that share one camshaft. Further, for example, in a V-type 6-cylinder internal combustion engine, one guide bridge 20 is provided for each of the three opposing cylinders, and each bridge 20 extends over all three cylinders that share one camshaft. It is an integral shape.
This support portion has a bridge portion 41 having a semi-circular recess 41a in order to increase the rigidity of the entire guide bridge 40.
And a cap portion 42 having a semicircular recess 42a. 4 for the bridge part 41 and the cap part 42
It is fastened by bolts 43 at points. The connecting portion 42b of the cap portion 42 extending in the axial direction is formed by the cam 14
It is located at a position distant from the camshaft 14 in the radial direction so as not to interfere with a and 14b (see FIG. 4).

Further, as shown in FIGS. 2 and 3, a tooth 44a is formed in an arc shape at one position on the upper end of the guide bridge 40.
The worm wheel 44 in which is formed is integrally provided. In this worm wheel 44, another worm wheel 45 having the same tooth 45a as the tooth 44a of this wheel 44 is provided in order to eliminate backlash with the worm gear 51 described later.
It is attached with the phase slightly shifted with respect to a. A spring 46 is provided between the wheels 44 and 45 to urge the wheels 44 and 45 in a direction to separate them.

The drive mechanism 50 includes a rotary shaft 52 having a worm gear 51 meshing with the teeth 44a of the worm wheel 44, a motor 53 for rotating the rotary shaft 52, an engine speed (Ne), and a load ( Accelerator opening, accelerator pedal depression amount, throttle opening, intake pressure Pb
Etc.), an ECU (electronic control unit) 54 that outputs a command signal to the motor 53 according to the operating state of the internal combustion engine determined by at least one factor of the engine temperature (water temperature, oil temperature, etc.).
And a signal representing the detected value of the rotational speed or rotational angle of the worm gear 51 as a feedback signal.
It is composed of a detector 55 for outputting to 54.

One end of the rotary shaft 52 is supported by a bearing 22 attached to a motor 53, and the motor 5
It is connected to three output shafts. The motor 53 has a bottom 24
a is the bolt 220 on the upper end surface of the cam holder 210.
It is supported by a bracket 24 fixed by. on the other hand,
The other end of the rotating shaft 52 is supported by a bearing 26 held in the bracket 25. The bottom 25a of the bracket 25 is attached to the upper end surface of the cam holder 210 by the bolt 22.
It is fixed at 0.

Next, the operation of the first embodiment having the above construction will be described.

First, the rocker arm 19 is used by the intake valve cam 1
To act on the trailing with respect to the 4b cam lift, the camshaft 14, as shown in FIGS. 6 and 7,
A case will be described in which the crankshaft of the internal combustion engine is rotated counterclockwise at a rotation speed of ½ of that of the crankshaft in association with the rotation of the crankshaft.

Now, it is assumed that the second rotating body 35 of each transmitting member 30 of each cylinder is in contact with the slipper surface 19b of the rocker arm 19 at its most distal end side, as shown in FIG. That is, in the transmission member 30, the straight line O ₁ connecting the center of the roller inner shaft 31 and the rotation center of the cam shaft 14 is inclined by the angle α from the reference line O ₀ . In this case, the lever ratio of the rocker arm 19 is the smallest.

When the camshaft 14 rotates counterclockwise in this state, the shaft portion 31 of the transmission member 30 is held by the guide groove 40a of the guide bridge 40 so as to be displaceable only in the radial direction of the camshaft 14. The cam lift of the intake valve cam 14b holds the first rotating body 33 in contact with the cam surface of the cam 14b, the shaft portion 31 holding the rotating body 33, and the slipper held by the shaft portion 31. It is transmitted to the rocker arm 19 via the second rotating body 35 that is in contact with the surface 19b, whereby the rocker arm 1
9, the intake valve 12 is opened and closed. At this time, the intake valve 12 begins to open at the crank angle a ₁ position, reaches the maximum lift at the crank angle a ₂ position, and closes at the crank angle a ₃ position, as shown by the solid line in FIG. 8B. To lift. The maximum lift at this time is β × L (0 <β <1).

In this state, when a command signal is output from the ECU 54 to the motor 53 for swinging the transmission member 30 clockwise from the position of FIG. 53 rotates, and this rotation is transmitted to the guide bridge 40 via the rotary shaft 52, the worm gear 51, and the worm wheel 44, and the guide bridge 40 swings clockwise from the position of FIG. 2 with the cam shaft 14 as a fulcrum. .. This swing is transmitted to the shaft portion 31 of the transmission member 30, and the transmission member 30 swings clockwise from the position of FIG. 6 to the position of FIG. 7 by the angle θ. Due to this swinging, the second rotating body 35, which was in contact with the slipper surface 19b at its most distal end side, is in contact with the slipper surface 19b at the position closest to the support shaft 20 of the rocker arm 19, whereby the lever ratio of the rocker arm 19 is increased. Is the largest.

In this case, the cam lift of the intake valve cam 14b causes the first rotary body 33, the shaft portion 31 and the second rotary body 35 to move.
When it is transmitted to the rocker arm 19 via the intake valve 12
Is the crank angle a ₁ ′ as shown by the solid line in FIG.
The valve starts to open at the position, reaches the maximum lift at the crank angle a ₂ ′ position, and lifts so as to close at the crank angle a ₃ ′ position. That is, when the transmission member 30 is swung by the angle θ from the position of FIG. 6 to the position of FIG. 7, the swing member 30 approaches the support shaft 20 of the rocker arm 19, and the lever of the rocker arm 19 is moved by 1 / β. The ratio becomes large, whereby the lift of the intake valve 12 is advanced by θ in crank angle and the maximum lift amount becomes large. The maximum lift at this time is L.

As is clear from the above description, when the rocker arm 19 is configured to act on the trailing with respect to the cam lift of the intake valve cam 14b, the transmission member 30 is swung by an arbitrary angle to advance. When the valve is angled, the lift of the intake valve 12 is advanced by this angle and the maximum lift amount is increased. Therefore, by swinging the transmission member 30, the valve timing and the maximum lift amount of the intake valve 12 are changed to the internal combustion engine. It can be continuously changed according to the operating state of the engine.

Contrary to the above, the camshaft 14 is moved so that the rocker arm 19 acts on the cam lift of the intake valve cam 14b in a leading manner.
As indicated by 0, the crankshaft 14
The case of rotating at a rotation speed of / 2 will be described.

As shown in FIG. 9, when the second rotary body 35 is in contact with the slipper surface 19b at its most distal end side and the lever ratio of the rocker arm 19 is the smallest, the intake valve 12 is operated as shown in FIG. As indicated by the solid line in b), the valve starts to open at the crank angle b ₁ position, reaches the maximum lift at the crank angle b ₂ position, and closes at the crank angle b ₃ position. The maximum lift at this time is β × L (0 <β <
1).

Then, the transmission member 30 is swung clockwise from the position of FIG. 9 by the angle θ to the position of FIG.
When the rocker arm 19 comes into contact with the slipper surface 19b at a position closest to the support shaft 20, the lever ratio of the rocker arm 19 is maximized.
In this state, the intake valve 12 begins to open at the crank angle b ₁ ′ position, reaches the maximum lift at the crank angle b ₂ ′ position, and reaches the crank angle b ₃ ′ position, as shown by the solid line in FIG. Lift to close the valve. The maximum lift at this time is L. That is, when the transmission member 30 is swung in the counterclockwise direction by the angle θ from the position of FIG. 10 to the position of FIG. 9 to advance the swing member 30, the swing member 30 moves the support shaft 20 of the rocker arm 19.
Further, the lever ratio of the rocker arm 19 becomes smaller by β, and the lift of the intake valve 12 is advanced by θ at the crank angle, and the maximum lift amount becomes smaller.

As is clear from the above description, in the case where the rocker arm 19 is configured to act on the cam lift in a leading manner, when the transmission member 30 is swung by an arbitrary angle to advance the angle, this angle is moved by this angle. Since the start of the lift of the intake valve 12 is advanced and the maximum lift amount is reduced, the valve timing of the intake valve 12 and the maximum lift amount are changed according to the operating state of the internal combustion engine by swinging the transmission member 30. It can be changed continuously.

According to the first embodiment described above, the transmission member 30 is swung about the rotation center of the camshaft 14 to change the valve timing and the lift amount of the intake valve 12 of each cylinder. The member 30 is a member that transmits the cam lift to the rocker arm 19 and is small and lightweight, so that the driving force for swinging the member is small and the swing range of the transmitting member 30 can be sufficiently secured. Further, since the transmission member 30 swings around the cam shaft 14 as a fulcrum, it is not necessary to specially provide a swing shaft.
Therefore, while the size of the entire cylinder head can be reduced, a sufficient adjustment range of the valve timing of the intake valve 12 can be ensured and the valve timing can be continuously changed, which facilitates application to a multi-cylinder internal combustion engine. become,
Moreover, the driving force for swinging the transmission member 30 is reduced.

Further, according to the first embodiment, since the roller outers 33 and 35 are used as the rotating bodies in the transmitting member 30, the driving force for swinging the transmitting member 30 is further reduced, and There is little wear at the contact portion between the intake valve cam 14b and the cam follower roller outer 33 and the contact portion between the rocker arm roller outer 35 and the slipper surface 19b of the rocker arm 19.

Further, according to the first embodiment, each transmission member 30 is rotatably supported by the roller inner shaft 31 and the shaft 31, and the intake valve cam 1 is provided.
A roller outer (first rotating body) 33 for a cam follower that abuts on the cam surface of 4b, and a pair of roller outers for rocker arms that are arranged on both sides of the roller outer 33 and are rotatably supported by the roller inner shaft 31. Since it is composed of (the second rotating body) 35, the roller outer 33 for the cam follower can rotate without slipping (the circumferential length of the intake valve cam 14b / the circumferential length of the roller outer 33) and each rocker arm can be rotated. Since the roller outer 35 for rotation rotates without slipping as much as it moves on the slipper surface 19b, wear of both roller outers 33, 35 is reduced, and as a result, durability of these is improved and total drive of the valve train is performed. The loss can be reduced.

In the first embodiment, the transmission member 30
Although rollers (roller outer 33, 35) are used as the rotating body in the above, the present invention is not limited to this. For example, the transmission member may be a cam lift for the rocker arm 1
9 is a member that is transmitted to the cam shaft 14, and is a contact point with the cam surface of the intake valve cam 14b at least when the lift is started at the time of swinging about the rotation center of the cam shaft 14, and the slipper surface 19b.
Any shape may be used as long as the contact point with and the center of rotation of the camshaft 14 are always located on a substantially straight line.
For example, the transmission member 30 is a surface that abuts the intake valve cam 14b and has an arcuate abutment surface that is convex toward the cam 14b side and a surface that abuts the slipper surface 19b of the rocker arm 19 that is the surface 19b. A transmission body having an arcuate contact surface that is convex toward the side; and a shaft portion that is integrally formed with the transmission body and that is held in the guide groove 40a so as to be displaceable only in the radial direction. Good.

Further, according to the first embodiment described above, two intake valve cams 14b, 14b are provided in each cylinder individually corresponding to the two intake valves 12, as shown in FIGS. With this configuration, it is possible to make the cam shapes of both cams 14b different according to requirements.

Further, in the first embodiment, the valve timing variable mechanism 60 is provided only in the intake valve operating mechanism 5, but the variable mechanism 60 is also provided in the exhaust valve operating mechanism 6. You may.

In the second embodiment of the present invention shown in FIG. 12, instead of the detector 55 in the first embodiment, the rotation angle (swing angle) of the guide bridge 40 is detected and the detected value is detected. The ECU 54 uses the signal as a feedback signal.
The detector 56 that outputs the signal is used.

Next, a third embodiment of the present invention will be described with reference to FIGS.

The third embodiment is constructed such that two intake valves 12 are driven by one rocker arm 19 in each cylinder.

That is, in the second embodiment, the camshaft 14 is provided with two exhaust valve cams 14a and one intake valve cam 14b for each cylinder. The transmission member 30 is arranged between the cam 14b and the slipper surface 19b of the rocker arm 19. The rocker arm 19 has bifurcated arms 19c 'and 19c', and the abutting member 21 is held at the end of each arm 19c 'in a positionally adjustable manner.

According to the third embodiment, the structure of the camshaft 14 is simpler than that of the first embodiment.
Since the number of rocker arms 19 is halved and the number of transmission members 30 is also halved, the number of parts is reduced as a whole, the entire cylinder head is further downsized, and the manufacturing cost is reduced.

Next, a fourth embodiment of the present invention will be described with reference to FIGS.

The fourth embodiment is different from the first embodiment in that the valve timing variable mechanism 60 provided in the exhaust valve valve mechanism 6 is different from the valve timing variable mechanism 60 provided in the intake valve valve mechanism 5. 70 is provided.

As the variable valve timing mechanism 70, for example, a known mechanism capable of switching the valve timing of the exhaust valve 13 between a low speed valve timing suitable for a low rotation range of the internal combustion engine and a high speed valve timing suitable for a high rotation range of the internal combustion engine. Can be used. That is, the variable valve timing mechanism 70 includes the first and second exhaust valve cams 14A and 14B having different profiles and the respective cams 1.
First and second cam followers 71 and 72 respectively holding cam followers 17A and 17B abutting on 4A and 14B,
A switching mechanism 7 having a switching pin 73 that is displaced by hydraulic pressure between a first position that connects the cam followers 71 and 72 and a second position (the position shown in FIG. 16) that releases the connection.
4 and.

[0053]

As described above in detail, the present invention (Claim 1)
According to the valve operating system for an internal combustion engine according to the present invention, the intake valve operating mechanism includes a cam shaft disposed above the cylinder head and a rocker arm that abuts on the cam of the cam shaft and swings around a fulcrum. And a valve operating device for an internal combustion engine including a valve operating mechanism for an exhaust valve, at least one of the valve operating mechanisms is provided with a cam lift disposed between the cam surface of the cam and the slipper surface of the rocker arm. A member that transmits to the rocker arm, and at the time of swinging around the rotation center of the cam shaft, the contact point with the cam surface, the contact point with the slipper surface, and the rotation center of the cam shaft at least at the start of lifting are always on a substantially straight line. The camshaft has a transmission member having a shape that is positioned and a guide portion that holds the transmission member so that the transmission member can be displaced only in the radial direction of the camshaft. A swing member which is movably supported,
When the transmission member is swung about the rotation center of the cam shaft, the variable valve timing mechanism having the drive mechanism for swinging the swing member according to the operating state of the internal combustion engine is provided. Since the lever ratio of the rocker arm changes according to the swing angle, the valve timing of the intake valve and / or the exhaust valve changes, and the transmission member is a member that transmits the cam lift to the rocker arm, it is small and lightweight. The driving force for rocking the shaft can be small, and the rocking shaft of the transmission member need not be specially provided. Therefore, while the size of the entire cylinder head can be reduced, the adjustment range of the valve timing can be sufficiently secured, the valve timing can be continuously changed, the application to a multi-cylinder internal combustion engine can be facilitated, and the driving force can be reduced. Can be reduced.

Further, according to the valve operating system of the internal combustion engine of the present invention (claim 5), since the rotating member of the transmission member is a roller, the driving force for swinging the transmission member is further reduced. At the same time, wear is reduced at the contact portion between the roller and the cam surface of the cam and at the contact portion between the roller and the slipper surface of the rocker arm, improving durability and reducing drive loss.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a valve train for an internal combustion engine according to a first embodiment of the present invention.

FIG. 2 is a view showing a valve operating system for an internal combustion engine according to a first embodiment, and is a cross-sectional view taken along line II of FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG.

4 is a sectional view taken along line IV-IV in FIG.

5 is a view on arrow V in FIG. 1. FIG.

6 (a) and 6 (b) are operation explanatory views of the first embodiment when the rocker arm acts on the trailing.

7A and 7B are views similar to FIGS. 6A and 6B, and an explanation of the operation when the transmission member is swung from the positions of FIGS. 6A and 6B. It is a figure.

8A is a graph showing valve lift characteristics in the cases of FIGS. 7A and 7B. FIG. (B) is FIG.
It is a graph which shows the valve lift characteristic in the case of (a) and (b).

9 (a) and 9 (b) are operation explanatory views of the first embodiment when the rocker arm acts on the leading.

FIGS. 10 (a) and 10 (b) are similar to FIGS. 9 (a) and 9 (b), and explanation of the operation when the transmission member is swung from the positions of FIGS. 9 (a) and 9 (b). It is a figure.

11A is a graph showing valve lift characteristics in the cases of FIGS. 10A and 10B. FIG. (B) is FIG.
It is a graph which shows the valve lift characteristic in the case of (a) and (b).

FIG. 12 is a schematic configuration diagram showing a main part of a valve train for an internal combustion engine according to a second embodiment of the present invention.

FIG. 13 is a diagram showing a valve operating system for an internal combustion engine according to a third embodiment of the present invention, which is similar to FIG.

FIG. 14 is a view showing a valve train for an internal combustion engine according to a third embodiment of the present invention, and is a sectional view similar to FIG.

FIG. 15 is a view showing a valve operating system for an internal combustion engine according to a fourth embodiment of the present invention, which is similar to FIG.

16 is a diagram showing a valve train for an internal combustion engine according to a fourth embodiment of the present invention, and is a diagram similar to FIG.

[Explanation of symbols]

 2 Cylinder head 5 Valve mechanism for intake valve 6 Valve mechanism for exhaust valve 14 Cam shaft 14a Exhaust valve cam 14b Intake valve cam 15,19 Rocker arm 19b Slipper surface 30 Transmission member 31 Roller inner shaft (shaft part) 33 Roller outer for cam follower (first rotating body) 35 Roller outer for rocker arm (second rotating body) 40 Guide bridge (oscillating member) 40a Guide groove (guide portion) 50 Drive mechanism 60 Valve timing variable mechanism

Claims (11)

[Claims] 1. A valve mechanism for an intake valve and a valve mechanism for an exhaust valve, each of which has a cam shaft arranged above a cylinder head and a rocker arm that abuts a cam of the cam shaft and swings around a fulcrum. In a valve operating device for an internal combustion engine comprising, at least one of the both valve operating mechanisms,
A member that is arranged between the cam surface of the cam and the slipper surface of the rocker arm to transmit the cam lift to the rocker arm, and is a member that is at least at the time of the lift start when swinging about the rotation center of the cam shaft. A transmission member having a shape such that the contact point, the contact point with the slipper surface, and the rotation center of the cam shaft are always located on a substantially straight line; A variable valve timing mechanism having a swinging member that is swingably supported by the camshaft and a drive mechanism that swings the swinging member according to the operating state of the internal combustion engine is provided. A valve operating device for an internal combustion engine, which is characterized. 2. The shaft of the transmission member, both ends of which are held by the guides of the swinging member, and the shaft of which is rotatably supported by the shaft, and is arranged between the cam surface and the slipper surface. The valve operating device according to claim 1, further comprising a rotating body. 3. The rotating body is divided into a first rotating body contacting the cam surface and a second rotating body contacting the slipper surface. Valve drive. 4. The valve gear according to claim 3, wherein the second rotating body is arranged on both sides of the first rotating body. 5. The valve operating device according to claim 2, wherein the rotating body is a roller. 6. The valve operating system according to claim 1, wherein the rocker arm of each valve operating mechanism can drive a plurality of intake valves or exhaust valves by displacement of one of the transmission members. 7. The valve operating system according to claim 1, wherein the swinging member has a support portion fitted to the outer peripheral surface of the shaft portion of the cam shaft. 8. The drive mechanism includes a worm wheel integrally provided with the swing member, a rotary shaft having a worm gear that meshes with teeth of the wheel, a motor for rotating the rotary shaft, and an engine speed. And an electronic control unit for outputting to the motor a command signal according to an operating state of the internal combustion engine, which is determined by at least one factor of load, engine temperature, and the like. apparatus. 9. The internal combustion engine has a plurality of cylinders, and the oscillating member has an integral shape extending over all cylinders sharing one camshaft, and is common to each cylinder.
The valve operating device according to claim 1, wherein the valve operating device is supported by a camshaft of a book. 10. The valve operating system according to claim 1, wherein the variable valve timing mechanism is provided only in the intake valve operating mechanism. 11. The valve operating system according to claim 10, wherein a valve timing variable mechanism different from the intake valve operating mechanism is arranged in the exhaust valve operating mechanism.