JPH08218831A - Valve system for internal combustion engine - Google Patents

Abstract

PURPOSE: To control change of a timing correctly and at high responsiveness in a valve system for an internal combustion engine provided with a rocker arm of which valve lift timing can be changed by changing a position of a shaft as a turning support point. CONSTITUTION: A shaft 13 and a cam shaft 8 are engaged with each other by a cam shaft engagement bracket 14. In the meanwhile, a valve timing changing shaft 15 is rotated by a motor 30 actuated by a timing changing instruction through a gear mechanism comprising a pinion 31 and a gear 32. To the valve timing changing shaft 15, one end of a fork lever 17 is fixed, the shaft 13 is engaged in its fork groove, and it is turned in a direction of an arrow A or B, so the position of the shaft 13 is changed and controlled. Because control force from the motor 30 is transmitted by a mechanically strong transmitting mechanism like the gear mechanism 32, a control system of a strong rigidy can be provided, thereby the control force can be correctly and speedily transmitted.

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 which can change the lift timing of the valve by changing the position of a shaft serving as a pivot.

[0002]

2. Description of the Related Art In a valve operating system of an internal combustion engine, a position of a shaft serving as a rotation fulcrum is provided between a cam providing a driving force for opening and closing a valve and a rear end of the valve to which the driving force is transmitted. There are some rocker arms that are changed. By changing 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. Hereinafter, a conventional rocker arm in which the position of the rotation fulcrum is not changed is referred to as a first rocker arm, and a rocker arm in which the position of the rotation fulcrum is changed is referred to as a second rocker arm.

FIG. 6 is a diagram showing such a conventional valve operating system for an internal combustion engine. In FIG. 6, 20 is a cam, 21
Is a shaft, 21C is a center, 22 is a second rocker arm, 23 is a shaft, 23C is a center, 24 is a first rocker arm, 24-1 is a guide groove, 25 is a shaft, 26
Is a valve, 27 is a valve timing variable lever, A,
B is an arrow. Each of the first rocker arm 24 and the second rocker arm 22 is an end pivot type rocker arm having a rotation fulcrum at one end. The shaft 21 of the cam 20 and the shaft 23 of the second rocker arm 22
Are supported by a valve timing varying lever 27.

The cam 20 is in contact with the upper surface of the second rocker arm 22, and the tip end of the second rocker arm 22 is fitted into and is in contact with the guide groove 24-1 provided in the upper portion of the rocker arm 24. The guide groove 24-1 is provided to prevent the tip from coming off the rocker arm 24. The lower end of the rocker arm 24 comes into contact with the rear end of the valve 26, and the valve 26 is opened by pressing it.

FIG. 7 shows a lever 2 for varying valve timing.
7 is shown. The reference numerals correspond to those in FIG.
Reference numeral -2 is a support hole, 27-3 is an end connecting portion, 28 is a return spring, and 29 is a wire. The end of the shaft 21 of the cam 20 is inserted into the support hole 27-1, and the shaft 23 of the second rocker arm 22 is inserted into the support hole 27-2.
The ends of are inserted and supported respectively. End connection part 2
One end of a wire 29 is connected to a substantially central portion of 7-3,
Return springs 28 are attached to both sides of the valve timing varying lever 27.

Since the position of the shaft 21 of the cam 20 is fixed, when the wire 29 is pulled in the arrow direction, the valve timing changing lever 27 is rotated in the arrow B direction,
When the force of the wire 29 is weakened, it is pulled back by the return spring 28 and rotated in the direction of arrow A. By this rotation, the shaft 23 inserted into the support hole 27-2 also
As shown in FIG. 6, it is rotated in the direction of arrow A or B. The directions of arrows A and B are directions along an arc centered on the center 21C of the shaft 21 of the cam 20. When it is desired to change the relationship between the valve lift amount and the lift timing, the shaft 23 of the second rocker arm 22 is moved in the arrow A or B direction by the above rotation.

FIG. 5 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 23C of the shaft 23 is in the standard position. A curve A is a curve when the center 23C is moved in the direction A of FIG. 6 about the center 21C of the cam 20,
It is suitable when you want to make the internal combustion engine have 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.

[0009]

[Problems to be Solved by the Invention]

(Problem) However, in the above-described conventional valve operating system, since the rigidity of the control system for changing the valve lift timing is weak (the control force is not transmitted quickly), accurate control is required especially in a multi-cylinder internal combustion engine. Moreover, there is a problem that it cannot be performed with good responsiveness.

(Explanation of Problems) The valve lift timing is changed by pulling the valve timing varying lever 27 with a wire 29 or with a return spring 28, as shown in FIG. . Generally, the wire is stretched to some extent during use, and the strength of the return spring is also changed. Further, in the case of a multi-cylinder, the operating status of each valve is different, and the force against the control force of the wire 29 and the return spring 28 is different from time to time.

For example, depending on the depressed position of each valve (26 in FIG. 6), the second rocker arm (22 in FIG. 6) of each cylinder is moved from the spring (2 in FIG. 2) attached to the valve. The force received is different. Therefore, if the return spring 28 tries to pull it back in the direction of arrow A, the force against it will be different at that time. Therefore, when the resisting force is large, the control force is not transmitted promptly, and the control is not performed accurately and with good responsiveness. An object of the present invention is to solve such a problem.

[0012]

In order to solve the above-mentioned problems, according to the present invention, 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 shaft which is a fulcrum of rotation. In a camshaft engagement bracket for engaging the shaft with a camshaft, a valve timing varying shaft rotated by a force transmitted from a driving means, and one end fixed to the valve timing varying shaft. The groove comprises a fork lever engaged with the shaft.

Further, a camshaft engaging bracket for engaging the shaft with the camshaft, a valve timing changing shaft rotated by a force transmitted from a driving means, and fixed to the valve timing changing shaft. A gear mechanism in which a gear and a gear fixed to the shaft are in mesh may be provided.

[0014]

[Operation] The drive source for changing and controlling the position of the rocker arm shaft that can change the valve lift timing is a motor or air cylinder, and the control force transmission mechanism is a mechanical mechanism such as a gear mechanism or a link lever mechanism. It has a strong mechanism and a rigid control system. As a result, even if the internal combustion engine has multiple cylinders, the control force is promptly transmitted, and the valve lift timing change control is performed.
It becomes possible to carry out accurately and responsively.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 is a diagram showing the entire valve operating system for an internal combustion engine according to the present invention, and FIG. 3 is a plan view of the second rocker arm 12. In these drawings, 1 is a valve, 2 is a spring, 3 is a spring bearing, 4 is a cotter, 5 is an adjuster, 6 is a first rocker arm, 7 and 8 are shafts, 8
C is the center of the shaft, 9 is a cam, 10-1 and 10-2 are rollers, 11 is a shaft, 12 is a second rocker arm, 1
3 is the shaft, and 13C is the center of the shaft.

Two rollers 10 having a common shaft (shaft 11) are provided at the tip of the second rocker arm 12.
1, 10-2 are attached. Then, as shown in FIG. 3, the roller 10-1 contacts the cam 9 and the roller 1
0-2 is arranged so as to contact the first rocker arm 6. Since all the contact from the cam 9 to the first rocker arm 6 in the driving force transmission path is the rolling contact by the roller, the force for driving the cam 9 is the same as the conventional one in which the contact is the sliding contact. Compared to this, it is smaller, and it can be driven with a light force even in the case of multiple cylinders.

The contact surface 6-1 of the first rocker arm 6 is
The surface is an arc centered on the center 8C of the shaft 8. The reason is to prevent the position of the first rocker arm 6 from changing when the position of the center 13C of the shaft 13 is moved in the direction A or B. Center 13
Since the movement of C in the direction of arrow A or B is the movement in the arc direction centered on the center 8C, if the contact surface 6-1 is also an arc surface centered on the center 8C, the center 13
Even if C is moved, the contact surface 6-1 only moves along the same arc as before, and 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 10-1 and the contact surface 6 of the first rocker arm 6 via the other roller 10-2.
-1 is pushed up. 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 spring force of the spring 2 causes the valve 1, the first rocker arm 6 and the second rocker arm 12 to return to their original positions.

(First Embodiment) FIG. 1 is a perspective view of a main portion of a first embodiment of the present invention. The symbols correspond to those in FIG.
Reference numeral 14 is a cam shaft engaging bracket, 15 is a valve timing varying shaft, 16 is a support base, 17 is a fork lever, and 18 is a pin. The variable valve timing shaft 15 is fitted on a support base 16, and a gear 32 is attached to an end of the support base 16. The gear 32 meshes with the pinion 31. Pinion 31 is motor 30
It is connected to the. When changing the valve lift timing, the motor 30 rotates the valve timing varying shaft 15 by rotating the pinion 31 in the forward or reverse direction according to a command from a controller (not shown).

One end of a fork lever 17 is fixed to the valve timing varying shaft 15 by a pin 18. In the fork groove of the fork lever 17, the second
The shaft 13, which is the rotation shaft of the rocker arm 12, is engaged. The fork lever 17 is rotated in the arrow A or B direction when the valve timing varying shaft 15 is rotated.

On the other hand, the shaft 8 extending to both sides of the cam 9
The camshaft engaging bracket 14 is engaged with each of these. FIG. 4 is a diagram showing the camshaft engagement bracket 14. 14-1 and 14-2 are divided halves, 14-3
Is a shaft insertion hole, 14-4 is a bolt, and 14-5 is a bolt hole. The engagement is performed by sandwiching the shaft 8 between the split halves 14-1 and 14-2 and screwing the bolt 14-4 into the bolt hole 14-5. Shaft insertion hole 14-
The shaft 13 of FIG. 1 is inserted through the shaft 3.

Returning to FIG. 1, the shaft 13 of the second rocker arm 12 and the valve timing varying shaft 15 whose position is fixed are connected via a fork lever 17.
Similarly, the shaft 8 which is also fixed in position is movably supported via the cam shaft engaging bracket 14. Therefore, the rotation of the fork lever 17 changes the position of the shaft 13, which changes the timing of valve lift.

The transmission of the control force when changing the valve lift timing is performed through the following route. Motor 30 (driving means) → pinion 31 → gear 32 → valve timing variable shaft 15 → fork lever 17 → shaft 13
(Final driven body). All the elements constituting this transmission path have a mechanically strong structure, and a control system having a high rigidity is realized. That is, even if the internal combustion engine has multiple cylinders and the force acting on the second rocker arm (12 in FIG. 2) varies depending on the operating position of each valve, it is almost affected by it. The control power can be quickly transmitted without the need. Therefore, even in a multi-cylinder internal combustion engine, control can be accurately and responsively performed.

In this embodiment, the motor 30 is used as the means for driving the variable valve timing shaft 15, but an air cylinder as used in the second embodiment below may be used.

(Second Embodiment) FIG. 8 is a perspective view of a main portion of a second embodiment of the present invention, and FIG. 9 is a view showing a camshaft engaging bracket of the second embodiment. Reference numerals correspond to those of FIG. 1, 33 is an air cylinder, 34 is an air pipe, 35 is a link, 36 is a lever, 37 is a gear, 38,
39 is a pin, 40 is a gear, 41 is a camshaft engaging bracket, 41-1 is a shaft insertion hole, 41-2 is an engaging recess, and L is an arrow.

The first difference from the embodiment of FIG. 1 is that
This is the point that a gear mechanism (37, 40) is used to transmit the rotation of the valve timing varying shaft 15 to the shaft 13 (the engaging mechanism by the fork lever 17 was used in the first embodiment). . The gear 37 is fixed to the valve timing varying shaft 15 by a pin 38, and the gear 40 is fixed to both ends of the shaft 13 by a pin 39. The gear 37 and the gear 40 are arranged so as to mesh with each other.

The second difference is that an air cylinder 33 is used as a drive means for rotating the valve timing varying shaft 15 (the motor 30 is used in the first embodiment). A lever 36 is connected to the end of the valve timing varying shaft 15, and the piston shaft of the air cylinder 33 is connected to the lever 36 via a link 35. The link 35 is moved by the arrow L by the air cylinder
When the valve timing variable shaft 15 is rotated in any of the directions, the control force is transmitted through the link lever mechanism, and the valve timing changing shaft 15 is rotated in the direction corresponding to the direction. The air supplied to the air cylinder 33 via the air pipe 34 is controlled by a controller (not shown).

The third difference is that the camshaft engaging bracket 41 is of a type simply hooked. It is shown in FIG. The shaft 13 is passed through the shaft insertion hole 41-1 and the engagement recess 41-2 is hooked on the shaft 8.

In the second embodiment, the control force is transmitted when changing the valve lift timing through the following route. Air cylinder 33 (driving means) → link 35 → lever 36 → valve timing variable shaft 15 → gear 3
7 → gear 40 → shaft 13 (final driven body). The elements that constitute this transmission path also have a mechanically strong structure, and a control system with high rigidity is also realized.

In this embodiment, the air cylinder 33 is used as means for driving the valve timing varying shaft 15, but the motor as used in the first embodiment may be used.

[0031]

As described above, according to the present invention, in the valve operating system of the internal combustion engine equipped with the rocker arm that can change the lift timing of the valve by changing the position of the shaft which is the pivot point, the position of the shaft can be changed. A motor and an air cylinder are used as the driving means for changing and controlling, and the control force transmission mechanism is a mechanically strong mechanism such as a gear mechanism and a link lever mechanism, so a highly rigid control system is realized. I was able to do it. Therefore, even if the internal combustion engine has many cylinders, the control force is transmitted promptly,
The valve lift timing change control can now be performed accurately and with good responsiveness.

[Brief description of drawings]

FIG. 1 is a perspective view of essential parts of a first embodiment of the present invention.

FIG. 2 is a diagram showing the entire valve operating device of the present invention.

FIG. 3 is a plan view of a second rocker arm.

FIG. 4 is a diagram showing a camshaft engaging bracket of the first embodiment.

[Fig. 5] Valve lift curve

FIG. 6 is a diagram showing a conventional valve operating system for an internal combustion engine.

FIG. 7 is a diagram showing a conventional valve timing variable lever.

FIG. 8 is a perspective view of essential parts of a second embodiment of the present invention.

FIG. 9 is a view showing a camshaft engaging bracket of the second embodiment.

[Explanation of symbols]

1 ... Valve, 2 ... Spring, 3 ... Spring receiver, 4 ... Cotter, 5
... Adjuster, 6 ... First rocker arm, 7, 8 ... Shaft, 8C ... Shaft center, 9 ... Cam, 10-1, 10
-2 ... roller, 11 ... shaft, 12 ... second rocker arm, 13 ... shaft, 13C ... shaft center, 14 ...
Camshaft engagement bracket, 15 ... Shaft for varying valve timing, 16 ... Support base, 17 ... Fork lever, 18 ... Pin, 20 ... Cam, 21 ... Shaft, 21C
... center, 22 ... second rocker arm, 23 ... shaft,
23C ... center, 24 ... first rocker arm, 24-1 ...
Guide groove, 25 ... Shaft, 26 ... Valve, 27 ... Valve timing variable lever, 28 ... Return spring, 29 ... Wire, 30 ... Motor, 31 ... Pinion, 3
2 ... Gear, 33 ... Air cylinder, 34 ... Air pipe, 3
5 ... Link, 36 ... Lever, 37 ... Gear, 38, 39 ...
Pins, 40 ... Gears, 41 ... Camshaft engagement brackets, 41-1 ... Shaft insertion holes, 41-2 ... Engagement recesses,
A, B, L ... Arrows

Claims (2)

[Claims] 1. A valve operating system for an internal combustion engine, comprising a rocker arm capable of changing a lift timing of a valve by changing a position of a shaft serving as a rotation fulcrum, and a cam shaft engaging the shaft with a cam shaft. A bracket, a valve timing variable shaft that is rotated by the force transmitted from the drive means, and a fork lever having one end fixed to the valve timing variable shaft and a fork groove engaged with the shaft. A valve operating system for an internal combustion engine, comprising: 2. A valve operating system for an internal combustion engine, comprising a rocker arm capable of changing a lift timing of a valve by changing a position of a shaft serving as a rotation fulcrum, and a cam shaft engaging the shaft with a cam shaft. A bracket, a valve timing variable shaft that is rotated by the force transmitted from the drive means, and a gear mechanism in which the gear fixed to the valve timing variable shaft and the gear fixed to the shaft are meshed. A valve operating system for an internal combustion engine, which is characterized by comprising: