JPH08165910A - Valve system of internal combustion engine - Google Patents

Abstract

PURPOSE: To reduce the driving force of a cam in a valve system of an internal combustion engine including a rocker arm, the turning fulcrum position of which is changed to change the lift timing of a valve. CONSTITUTION: Rollers 10, 13 are installed in at least one of contact places in a driving force transmitting path extending from a cam 9 as a driving source to a valve 1 to make the contact into rolling contact. Thus, a first rocker arm can be oscillated by light force, so that even if the number of cylinders of an internal combustion engine is increased, small cam driving force is enough. One 12-1 of contact surfaces in the driving force transmitting path is a circular- arc surface taking the center of the cam as the center. Though the relationship between the lift amount of the valve and the lift timing is changed by moving the position of the turning fulcrum 15C of a second rocker arm 12 in the direction of an arrow A or B, if the cam is a circular-arc surface, at the time of change, the position of the rocker arm 6 will not be changed.

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 equipped with a rocker arm that can change the lift timing of the valve by changing the position of a rotation fulcrum.

[0002]

2. Description of the Related Art In a valve operating system of an internal combustion engine, the position of a rotation fulcrum is changed from a cam providing a driving force for opening and closing a valve to a rear end of the valve to which the driving force is transmitted. Some rocker arms are interposed. By moving the position of the rotation fulcrum of the rocker arm along an arc centered on the center of the cam, the lift timing of the valve is changed as necessary.

FIG. 3 is a diagram showing such a conventional valve operating system for an internal combustion engine. In FIG. 3, 1 is a valve, 6 is a first rocker arm, 6G is a guide groove, 7 and 8 are shafts, 8C is a center, 9C is a cam, 12 is a second rocker arm, 15 is a shaft, and 15C is a center, A , B is an arrow. First rocker arm 6, Second rocker arm 12
Are end-pivot type rocker arms each having a pivot point at one end.

The cam 9 comes into contact with the upper surface of the second rocker arm 12, and the tip of the second rocker arm 12 is fitted into a guide groove 6G provided in the upper portion of the rocker arm 6,
Are in contact. The guide groove 6G is provided to prevent the tip from coming off the rocker arm 6. The lower end of the rocker arm 6 comes into contact with the rear end of the valve 1, and the valve 1 is opened by pushing it down.

When it is desired to change the relationship between the valve lift amount and the lift timing, the center 15C of the shaft 15 of the second rocker arm 12 is moved in the arrow A or B direction. The directions of the arrows A and B are along the arc centered on the center 8C of the shaft 8 of the cam 9.

FIG. 2 is a valve lift curve. The horizontal axis represents time (timing), and the vertical axis represents the valve lift amount.
The valve lift curve is a characteristic curve representing the relationship between the valve lift amount and the lift timing. The curve S is a curve when the center 15C of the shaft 15 is in the standard position. The curve A is a curve when the center 15C is moved in the direction A of FIG. 3 around the center 8C of the cam 9, and is suitable when the internal combustion engine is desired to have a high output. Curve B is a curve when moved in the B direction, and is suitable when the internal combustion engine is desired to have a low output.

A valve train for an internal combustion engine as described above is disclosed in, for example, Japanese Patent Laid-Open No. 64-53009.

[0008]

[Problems to be Solved by the Invention]

(Problem) However, the above-described conventional valve operating system for an internal combustion engine has a problem that a large force is required to drive the valve operating system in the case of a multi-cylinder internal combustion engine.

(Explanation of Problems) As can be seen from FIG. 3, in the valve operating apparatus as described above, some sliding contact portions are present in the driving force transmission path from the cam 9 to the valve 1. is there. That is, the cam 9 and the second rocker arm 12 are in sliding contact, and the tip of the second rocker arm 12 and the guide groove 6G are in sliding contact. In order to transmit the driving force while making such sliding contact, not only the driving force is supplied, but also the force that overcomes the frictional force of the sliding contact interposed during the transmission of the driving force is supplied. There must be.

Therefore, even though a single cylinder does not require a very strong force, a multi-cylinder requires a strong force because the frictional force is superposed. Since the force for rotating the cam 9 is also supplied from the engine, the load on the engine will be increased in the end. An object of the present invention is to solve the above problems.

[0011]

In order to solve the above-mentioned problems, the present invention relates to a valve operating system for an internal combustion engine, comprising a rocker arm capable of changing the position of a rotation fulcrum to change the lift timing of the valve, At least one of the contact points in the drive force transmission path from the cam that is the drive source to the valve
A roller for making the contact into a rolling contact is provided at a position, and one of the contact surfaces in the driving force transmission path is an arc surface centered on the center of the cam.

There are two rocker arms, a first rocker arm and a second rocker arm. The first rocker arm has means for engaging and contacting the rear end of the valve at one end, and the contact surface at the other end is the contact surface. The second rocker arm has an arc surface centered on the center of the cam, and the second rocker arm has a rotation fulcrum whose position is changed when the lift timing of the valve is changed. One roller and a second contacting said cam
The rollers may have a common shaft.

[0013]

[Operation] In a valve operating system of an internal combustion engine equipped with a rocker arm capable of changing the lift timing of the valve by changing the position of a rotation fulcrum, contact in a drive force transmission path from a cam as a drive source to the valve At least one of the places is provided with a roller for making the contact rolling contact, and the contact is rolling contact. As a result, the rocker arm is swung with a light force, so that the driving force of the cam can be small even if the number of cylinders of the internal combustion engine increases.

Further, one of the contact surfaces in the driving force transmission path is an arc surface centered on the center of the cam. When changing the relationship between the lift amount of the valve and the lift timing, it is performed by moving the position of the rotation fulcrum of the rocker arm, but if it is an arc surface as described above,
The position of the rocker arm which is in contact with the rear end of the valve is not changed during the change.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a valve train of an internal combustion engine equipped with a rocker arm capable of changing the lift timing of a valve by changing the position of a fulcrum of rotation, in a driving force transmission path between a cam and a valve. By replacing at least one of the sliding contact parts interposed in the above with a rolling contact part by a roller, the force for driving the valve operating device is reduced. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a diagram showing a first embodiment of the present invention. The reference numerals correspond to those in FIG. 3, and 2
Is a spring, 3 is a spring receiver, 4 is a cotter, 5 is an adjuster,
10 is a roller, 11 is a shaft, 12-1 is a contact surface, 1
3 is a roller, and 14 is a shaft. The components having the same reference numerals as those of the device in FIG. 3 are the same, so the description thereof will be omitted.

A roller 13 is attached to the tip of the second rocker arm 12 and is in contact with the cam 9 by the roller 13. The shaft 14 is the shaft of the roller 13. One end of the first rocker arm 6 is in contact with the rear end of the valve 1 via the adjuster 5, and the roller 10 is attached to the other end by a shaft 11 at the other end. The contact surface 12-1 of the second rocker arm 12 contacts the first rocker arm 6 via the roller 10.

The contact surface 12-1 is the center 8C of the shaft 8.
Make it the surface of an arc centered at. The reason is,
This is to prevent the position of the first rocker arm 6 from changing when the position of the center 15C of the shaft 15 is moved in the direction A or B (also in other embodiments described below,
This is for the same reason when the contact surface is an arc surface centered on the center 8C. ). Since the movement of the center 15C in the direction of arrow A or B is the movement in the arc direction centered on the center 8C, if the contact surface 12-1 is also an arc surface centered on the center 8C, the center 15C is Even if it is moved, the contact surface 12-1 only moves along the same arc as before, so that the first rocker arm 6 is not pushed up or lowered.

When the cam 9 rotates, the second rocker arm 12 is pushed up via the roller 13 and its contact surface 1
One end of the first rocker arm 6 is pushed up via the roller 10 that is in contact with 2-1. The first rocker arm 6 circularly moves around the shaft 7, and the adjuster 5 at the other end pushes the valve 1. When the pushing force of the cam 9 disappears, the elastic force of the spring 2 causes the valve 1, the first
The rocker arm 6 and the second rocker arm 12 return to their original positions.

Since the contact from the cam 9 to the first rocker arm 6 in the driving force transmission path is all rolling contact by the roller, the force for driving the cam 9 is smaller than that of the conventional one, and the contact force is large. Even a cylinder can be driven with a light force.

(Second Embodiment) FIG. 4 is a diagram showing a second embodiment of the present invention. The reference numeral corresponds to that of FIG. 1 and is 6
-1 is a contact surface, 16 is a roller, and 17 is a shaft.
In this embodiment, rollers are provided only on the second rocker arm 12. The roller 1 is provided in the middle of the second rocker arm 12.
3, the roller 16 is attached to the tip, and the cam 9 is the roller 1
3 and contact with the first rocker arm 6 by the roller 16.

Also in this embodiment, all the contact from the cam 9 to the first rocker arm 6 in the driving force transmission path is rolling contact by the roller, so that the driving force can be small.
The contact surface 6-1 that contacts the roller 16 is an arc surface centered on the center 8C of the cam 9. When it is desired to change the valve lift timing, the center 15C is moved in the direction of arrow A or B.

(Third Embodiment) FIG. 5 is a view showing a third embodiment of the present invention, and FIG. 6 is a plan view of a second rocker arm 12 of this embodiment. Reference numerals correspond to those in FIGS. 1 and 4, and 13-1 and 13-2 are rollers. In this embodiment, two rollers 13-having a common shaft (shaft 14) are provided at the tip of the second rocker arm 12.
Attach 1, 13-2. Then, as shown in FIG. 6, the roller 13-1 contacts the cam 9 and the roller 13-2
Are arranged so as to contact the first rocker arm 6.

In the embodiment of FIGS. 1 and 4, the two rollers are arranged in the longitudinal plane of the second rocker arm 12. In a sense, they are arranged in series spatially. Therefore, the height of the valve train becomes high. This third embodiment is intended to reduce the height as much as possible. In the third embodiment, the two rollers 13-
1 and 13-2 are arranged side by side in the lateral direction with respect to the longitudinal direction of the second rocker arm 12,
It is possible to reduce the height of the valve train as compared with the embodiment of FIG. The other points are similar to those of the embodiment shown in FIG.

(Fourth Embodiment) FIG. 7 is a diagram showing a fourth embodiment of the present invention. (A) and (b) are two examples of the fourth embodiment. The reference numerals correspond to those in FIGS. 1 and 4. The purpose of the fourth embodiment is to reduce the cam driving force and the height of the valve operating device while keeping the cost low by using only one roller. .

The cam 9 and the second rocker arm 12 are in contact with each other via the roller 13, but the contact surface of the second rocker arm 12 and the contact surface 6-1 of the first rocker arm 6 are in contact with each other. Not through Laura. Since only the roller is used for the contact portion with the cam 9, the friction force is larger than that of the embodiment (example, FIG. 4) in which any contact is made by the roller. However, if one roller is omitted, the height of the valve operating device can be reduced and the cost can be reduced as compared with the embodiment shown in FIG. Therefore, this embodiment is sufficient when the number of cylinders is not so large.

(Fifth Embodiment) FIG. 8 is a diagram showing a fifth embodiment of the present invention. The reference numerals correspond to those in FIG. 7. This is also aimed at reducing the driving force of the cam while keeping the cost low with one roller, and at the same time reducing the height of the valve train. The surface 12-2 of the second rocker arm 12 that contacts the cam 9 is a flat surface, and the surface 12-1 of the first rocker arm 6 that contacts the roller 10 is an arc surface having the center 8C of the shaft 8 as the center. .

The difference from the fourth embodiment lies in the difference in the mounting position of the roller. In the fourth embodiment, the roller is the second.
It is attached to the rocker arm 12, whereas in the fifth embodiment, it is attached to the first rocker arm 6.

(Sixth Embodiment) FIG. 9 is a diagram showing a sixth embodiment of the present invention. This is the second rocker arm 1
Not only the second rocker arm 6 but also the first rocker arm 6 is an example in which a so-called end pivot type rocker arm in which the shaft 7 is provided at the end is used. The two rollers 10 and 13 are arranged in series as in the embodiment of FIG. Contact surface 12 of the second rocker arm 12-
Reference numeral 1 denotes an arc surface centered on the center 8C of the shaft 8 of the cam 9.

(Seventh Embodiment) FIG. 10 shows a seventh embodiment of the present invention.
It is a figure which shows the Example of. The reference numerals correspond to those of FIGS. 1 and 4, and 18 is a tappet and 19 is a shim (note that, in this example, the rocker arm is only the first rocker arm 6, so it is simply referred to as “rocker arm” here. I will decide). This is an example in which the present invention is applied to a direct attack type valve operating device.

A shim 19 having a flat surface is provided on the top of the tappet 18 so as to make contact with the contact surface 6-1 of the rocker arm 6 of the end pivot type. The contact surface 6-1 is an arc surface centered on the center 8C of the shaft 8 of the cam 9. A roller 10 is attached to the rocker arm 6 and comes into contact with the cam 9 via the roller 10. Since the contact between the rocker arm 6 and the cam 9 is rolling contact by the roller 10, the driving force of the cam 9 is reduced.

When it is desired to change the relationship between the lift amount and the lift timing, the center 7C of the shaft 7 of the rocker arm 6 is moved along the arc of the center 8C of the shaft 8 of the cam 9 as Direction or B direction. Since the contact surface 6-1 is an arc surface centered on the center 8C, even if the center 7C is moved as described above,
Therefore, the shim 19 is not pressed.

(Eighth Embodiment) FIG. 11 shows an eighth embodiment of the present invention.
It is an example of. The reference numeral corresponds to that of FIG.
1 is a shim surface. The shim surface 19-1 is an arc surface centered on the center 8C of the shaft 8 of the cam 9.
Roller 1 attached to the tip of rocker arm 6
0 is in contact with shim surface 19-1. The contact surface 6-1 of the rocker arm 6 is a flat surface and is in contact with the cam 9. The other points are similar to those of the embodiment shown in FIG.

[0034]

As described above, according to the present invention, in the valve operating system of the internal combustion engine having the rocker arm capable of changing the position of the rotation fulcrum to change the lift timing of the valve, from the cam to the valve. Since the roller is provided at at least one of the contact points in the driving force transmission path and the contact is a rolling contact, the driving force of the cam can be small even if the number of cylinders of the internal combustion engine increases. Further, since one of the contact surfaces in the drive path is an arc surface centered on the center of the cam, when the relationship between the valve lift amount and lift timing is changed, the contact contact with the rear end of the valve is made. It does not change the position of the rocker arm.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

[Fig. 2] Valve lift curve

FIG. 3 is a diagram showing a conventional valve operating system for an internal combustion engine.

FIG. 4 is a diagram showing a second embodiment of the present invention.

FIG. 5 is a diagram showing a third embodiment of the present invention.

FIG. 6 is a plan view of a second rocker arm of the third embodiment.

FIG. 7 is a diagram showing a fourth embodiment of the present invention.

FIG. 8 is a diagram showing a fifth embodiment of the present invention.

FIG. 9 is a diagram showing a sixth embodiment of the present invention.

FIG. 10 is a diagram showing a seventh embodiment of the present invention.

FIG. 11 is a diagram showing an eighth embodiment of the present invention.

[Explanation of symbols]

1 ... Valve, 2 ... Spring, 3 ... Spring receiver, 4 ... Cotter, 5
... adjuster, 6 ... first rocker arm, 7, 8 ... shaft, 9 ... cam, 10 ... roller, 11 ... shaft, 12
... second rocker arm, 13, 13-1, 13-2 ... roller, 14, 15 ... shaft, 15C ... center, 16 ... roller, 17 ... shaft, 18 ... tappet, 19 ... shim

Claims (2)

[Claims] 1. A valve operating system for an internal combustion engine, comprising a rocker arm capable of changing a position of a rotation fulcrum to change a lift timing of a valve, in a drive force transmission path from a cam as a drive source to a valve. At least one of the contact points is provided with a roller for making the contact a rolling contact, and one of the contact surfaces in the driving force transmission path is an arc surface centered on the center of the cam. And a valve operating device for an internal combustion engine. 2. A first rocker arm having means for engaging and contacting a rear end of the valve at one end, and a contact surface at the other end being an arcuate surface centered on the center of the cam, and a first rocker arm of the valve. It has a rotation fulcrum whose position is changed when changing the lift timing, and a first roller contacting with the contact surface and a second roller contacting with the cam share a shaft at the rotation tip. The valve operating system for an internal combustion engine according to claim 1, further comprising a second rocker arm provided.