JPH11210435A - Variable valve system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable valve system of internal combustion engine capable of preventing a rocker arm from being worn. SOLUTION: A link mechanism L for opening and closing an intake valve 10 comprises a rocker arm 14 fitted rotatably onto a control shaft 12, a link arm 5 fitted rotatably onto the outer periphery of an eccentric cam 4, an oscillating cam 8 which is fitted swingably on the outer periphery of a camshaft 3 and has a cam surface 8b in contact slidably with a valve lifter, and a link member 7 and pins 15, 16, and 18 for joining them to each other. A clearance L5 between the oscillating cam 8 and a cam bracket 7 is reduced smaller than that L3 between the rocker arm 14 and the cam bracket 7, and a clearance L4 between the oscillating cam 8 and the eccentric cam 4 is reduced smaller than a clearance L2 between the rocker arm 14 and the link arm 5. Thus, even if the oscillating cam 8 is brought into contact with an adjacent member, the rocker arm 14 is not brought into contact with the adjacent member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve apparatus for an internal combustion engine which can change the opening / closing timing of an intake / exhaust valve and the valve lift according to the operating state of the engine.

[0002]

2. Description of the Related Art A variable valve train of this type is used to improve fuel efficiency at low engine speed and low load, to ensure stable driving performance, and to secure sufficient output by improving intake air filling efficiency at high speed and high load. In addition, the opening / closing timing of the intake / exhaust valves and the valve lift amount are variably controlled in accordance with the operating state of the engine, and various configurations have conventionally been devised.

[0003] For example, a variable valve device disclosed in Japanese Patent Application Laid-Open No. Sho 60-1312 is configured as shown in FIG. That is, in the variable valve operating device 30, the rocker shaft 31 is rotatably supported by the cylinder head 32, and one end of the first rocker arm 33 and one end of the second rocker arm 34 are rotatably supported by the rocker shaft 31. Supported by the first rocker arm 33 and the second rocker arm 3
The first rocker arm 33 and the second rocker arm 34 are arranged adjacent to each other.
The movement of the rocker shaft 31 in the axial direction is restricted by the shaft. The second rocker arm 34 is provided with a follower 35 that slides on a cam (not shown). When no oil pressure acts on the oil passage 36, the first rocker arm 33
Is stationary (valve stopped state), the movement of the cam is transmitted only to the second rocker arm 34, and the valve 37 is opened and closed by the second rocker arm 34. Next, when hydraulic pressure is applied, a piston (not shown) housed inside the first rocker arm 33 enters the second rocker arm 34, and the first rocker arm 33 and the second rocker arm 34 are connected, and the valve 38 and the valve 37 are connected. Is both rocker arms 33,3
It is opened and closed by 4.

[0004]

However, in such a conventional technique, when the hydraulic pressure does not act and the second rocker arm 34 independently opens and closes the valve 37, the fulcrum center line A of the second rocker arm 34 is not used. Follower 3 against
5 is in an offset state, and the second rocker arm 34 oscillated by a cam (not shown) falls down in the axial direction of the rocker shaft 31. As a result, the second rocker arm 34 makes a one-sided contact between the first rocker arm 33 and the cylinder head 32, and causes abrasion due to the one-sided contact on the sliding contact surface with the first rocker arm 33 and the sliding contact surface with the cylinder head 32. Further, there is a possibility that a malfunction of the mechanism due to the abrasion powder may occur.

Accordingly, an object of the present invention is to provide a variable valve train for an internal combustion engine that can prevent wear of the rocker arm.

[0006]

According to a first aspect of the present invention, there is provided a camshaft which rotates in synchronization with the rotation of an engine and has an eccentric cam on an outer periphery, and a control shaft arranged in parallel to the camshaft. A link mechanism which operates in accordance with the rotation of the eccentric cam of the camshaft to open and close the intake / exhaust valve. Among these, the link mechanism is rotatably fitted to the outer periphery of the eccentric cam of the camshaft and the rocker arm rotatably fitted to the control shaft, and the tip is rotatable at one end of the rocker arm. And a link member rotatably connected to the other end of the rocker arm, and a swingably fitted outer periphery of the camshaft, and a tip end rotatable on the link member. And a swinging cam having a cam surface slidably in contact with the valve lifter. Then, the movement of the link mechanism in the camshaft axial direction is regulated by bringing both sides of the swing cam orthogonal to the camshaft into contact with adjacent members. Here, the eccentric cam is fixed to the outer periphery of the camshaft by press fitting or the like, or is formed integrally with the outer periphery of the camshaft.

[0007] The invention of claim 2 is characterized in that a thrust member is arranged between at least one of the side surfaces of the swing cam orthogonal to the camshaft and the adjacent member.

According to a third aspect of the present invention, the fitting surface width of the eccentric cam with the link arm is determined by changing the fitting surface width of the link arm with the eccentric cam and the amount of movement of the link mechanism in the camshaft axial direction. It is characterized by being larger than the sum of

[0009]

According to the first aspect of the present invention, the movement of the link mechanism in the axial direction of the camshaft is regulated by contacting both sides of the swing cam, which are perpendicular to the camshaft, with adjacent members. As a result, the rocker arm of the link mechanism does not slide on the adjacent member to cause wear, and the wear of the rocker arm reduces the durability of the variable valve gear and the malfunction of the link mechanism due to abrasion powder. Will not be invited.

According to the second aspect of the present invention, a thrust member is arranged between at least one of the side surfaces of the swing cam and an adjacent member, and the side surface of the swing cam contacts the thrust member. The contact mechanism restricts the movement of the link mechanism in the camshaft axial direction, so that the wear of the swing cam and the adjacent members is reduced, and the durability of the variable valve apparatus is further improved.

According to the third aspect of the present invention, the fitting area between the link arm and the eccentric cam does not decrease even if the link mechanism moves in the camshaft axial direction. Abrasion of the sliding contact portion can be suppressed, and the durability of the variable valve operating device is improved.

[0012]

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

[First Embodiment] FIG. 1 is a front view of a main part of a variable valve apparatus 1 for an internal combustion engine according to the present embodiment, FIG. 2 is a plan view of the variable valve apparatus 1, and FIG. It is a side view of the same variable valve apparatus 1. As shown in FIGS. 1 to 3, the camshaft 3 rotatably supported on the upper portion of the cylinder head 2 is connected to a crankshaft of an internal combustion engine (not shown) and rotates in synchronization with the rotation of the internal combustion engine. It has become. An eccentric cam 4 is provided on the outer periphery of the camshaft 3.
Is press-fitted, and the camshaft 3 and the eccentric cam 4 rotate integrally. A base 5 a of a link arm 5 is rotatably fitted to the outer periphery of the eccentric cam 4. The upper part of the cylinder head 2 and the cylinder head 2
A cam bracket 7 (7
A swing cam 8 is arranged between the link arm 5 and the link arm 5. The swing cam 8 has a fitting hole 8a rotatably fitted to the outer periphery of the camshaft 3 and a cam surface 8b which is in sliding contact with the valve lifter 11 of the intake valve 10.

On a cam bracket 7 fixed to the upper portion of the cylinder head 2, a control shaft 12 located above the camshaft 3 in FIG. 1 and arranged in parallel with the camshaft 3 is rotatable. It is supported by. This control shaft 12 has a control cam 13 formed on the outer periphery thereof, eccentric from the control shaft 12 by a predetermined amount. And
A fitting hole 14b of a base 14a of the rocker arm 14 is rotatably fitted on the outer periphery of the control cam 13. The rocker arm 14 has one end 14c connected to the tip 5b of the link arm 5 via a pin 15 and the other end 14d
Is connected to one end 17a of the link member 17 via the pin 16. The other end 17 b of the link member 17 is connected to the tip 8 c of the swing cam 8 via a pin 18.
The link arm 5, the rocker arm 14, the link member 17, the swing cam 8, and the pins 15, 16, and 18 linking them are operated with the rotation of the eccentric cam 4 of the camshaft 3 to operate the valve. A link mechanism L that opens and closes the intake valve 10 via the lifter 11 is configured. The valve lifter 11 moves up and down along a guide hole 2a formed in the cylinder head 2, and is urged toward the swing cam 8 by a valve spring (not shown) (FIGS. 1 and 3). reference). The rocker arm 14 is
As shown in FIG. 2, one end 14c and the other end 14c are provided.
d is formed so as to be shifted in the axial direction of the control shaft 12. The link mechanism L is, as shown in FIG.
The pair of intake valves 10 are symmetrically arranged with the cam bracket 7 interposed therebetween so as to open and close.

The control shaft 12 is connected to an electromagnetic actuator (not shown), and is rotated within a predetermined rotation angle range by the electromagnetic actuator. As a result, the control cam 13 of the control shaft 12 rotates, and the distance between the rocking center position of the rocker arm 14 and the rocking center position of the rocking cam 8 changes, and the link member 17 linked to the rocker arm 14 is changed. As a result, the swing cam 8 is swung, so that the initial position of the valve lifter 11 changes. As a result, the valve timing and the valve lift change. The operation of the electromagnetic actuator is controlled by a controller (not shown) that detects the operating state of the internal combustion engine.
The controller calculates the operating state of the engine based on detection signals from various sensors such as a crank angle sensor, an air flow meter, and a water temperature sensor, and outputs a control signal to the electromagnetic actuator based on the calculation result.

Here, a pin 15 for connecting the tip 5b of the link arm 5 and one end 14c of the rocker arm 14 so as to be relatively rotatable is fitted into a fitting hole 5c of the tip 5b of the link arm 5 and one end 14c of the rocker arm 14. It is fitted in the mating hole 14e, and retaining rings 20 for retaining are attached to both ends thereof. A pin 16 for rotatably connecting the other end 14 d of the rocker arm 14 and the one end 17 a of the link member 17 is provided with a fitting hole 14 f at the other end 14 d of the rocker arm 14 and a fitting hole at one end 17 a of the link member 17. 17c, and a retaining ring 21 for retaining at both ends thereof.
Is attached. Also, the other end 17 of the link member 17
b and the tip 8c of the swing cam 8 are connected to each other so as to be relatively rotatable.
d and a fitting hole 8d of the tip 8c of the swing cam 8, and a retaining ring 22 for retaining is attached to both ends thereof.

The variable valve train 1 configured as described above has the following features.
When the camshaft 3 rotates in synchronization with the rotation of the internal combustion engine, the link arm 5 is eccentrically moved with respect to the center axis of the camshaft 3 by the eccentric cam 4, and the rocker arm 14 is rotated around the control cam 13 by the link arm 5. Rocked. When the rocker arm 14 swings around the control cam 13, the swing cam 8 linked to the swinging rocker arm 14 via the link member 17 swings around the camshaft 3. At this time, as shown in FIGS. 1 and 3, a cam surface 8b formed on the outer periphery of the swing cam 8 slides on the top 11a of the valve lifter 11,
The valve lifter 11 urged upward by a valve spring (not shown) is moved up and down to open and close the intake valve 10.

When the one end 14c of the rocker arm 14 is pushed up by the link arm 5, the one end 14c and the other end 14d of the rocker arm 14 are displaced in the axial direction of the control shaft 12. Therefore, the point of action of the force is shifted in the axial direction of the control shaft 12 (see FIG. 2). Also, the fitting hole 1 of the rocker arm 14
There is a predetermined amount of fitting gap between 4b and control cam 13. As a result, in FIG. 3, the rocker arm 14 falls down so that the upper end thereof approaches the cam bracket 7. When the rocker arm 14 falls down, a component force in the thrust direction is generated in the rocker arm 14, so that the rocker arm 14 moves on the control shaft 12 toward the cam bracket 7. On the other hand, since the swing cam 8 is urged by a valve spring (not shown) and the fitting hole 8a is pressed against the camshaft 3, it is unlikely to fall. Therefore, in the present embodiment, the side surface 8e of the swing cam 8 orthogonal to the camshaft 3 is brought into contact with the adjacent upper side surface 2b of the cylinder head and the side surface 7c of the cam bracket, and the link mechanism L is moved in the camshaft 3 axial direction. Is regulated. That is,
In this embodiment, as shown in FIG. 3, the gap L5 between the side face 8e of the swing cam 8 and the cylinder head upper side face 2b and the cam bracket side face 7c is larger than the gap L3 between the rocker arm 14 and the cam bracket side face 7c. (L5 <
L3), so that the swing cam 8 comes into contact with the cylinder head 2 and the cam bracket 7 before the rocker arm 14,
The fallen rocker arm 14 is prevented from causing a side contact with the adjacent cam bracket 7. here,
Since the swing cam 8 is unlikely to fall as described above, the entire circumference of the side surface 8e abuts on the adjacent cylinder head 2 or cam bracket 7, and the cylinder head 2 or cam bracket 7 may be partially hit. Also, there is no possibility of early deterioration of durability due to uneven wear.

When one end 14c of the rocker arm 14 is pushed down by the link arm 5, the rocker arm 1
In FIG. 3, the upper portion 4 of FIG. 3 is tilted toward the link arm 5 adjacent thereto, and moves toward the link arm 5 by a thrust force generated due to the tilt. On the other hand, the swing cam 8
Is hard to fall as described above. Therefore, in this embodiment, the side face 8f of the swing cam 8 orthogonal to the camshaft 3 is provided.
Is brought into contact with the adjacent eccentric cam 4 to restrict the movement of the link mechanism L in the axial direction of the camshaft 3. That is, in the present embodiment, as shown in FIG. 3, the gap L4 between the side face 8f of the swing cam 8 and the side face of the eccentric cam 4 is made smaller than the gap L2 between the rocker arm 14 and the link arm 5 (L4 < L2) The rocking cam 8 is brought into contact with the eccentric cam 4 before the rocker arm 14 so that the rocker arm 14 that has fallen does not cause a single contact with the adjacent link arm 5. Here, the swing cam 8
Is hard to fall as described above and abuts the side surface of the adjacent eccentric cam 4 over the entire circumference, so that the early deterioration of the durability due to uneven wear does not occur.

Further, according to the present embodiment, as described above, the swing cam 8 is brought into contact with the adjacent member (the cylinder head 2, the cam bracket 7, the eccentric cam 4) to thereby provide the camshaft of the link mechanism L. Although the movement in the three-axis direction is restricted, the maximum movement amount of the link mechanism L is L4 +
L5, the fitting surface width of the eccentric cam 4 with the link arm 5 (that is, the width of the eccentric cam 4 in the camshaft axial direction) L1
+ ΔL1 is made larger than the sum of the fitting surface width L1 of the link arm 5 to the eccentric cam 4 (that is, the width dimension of the link arm 5) and the maximum movement amount L4 + L5 of the link mechanism L ((L1 + ΔL1)> (L1 + L4 + L5). ), The fitting area between the link arm 5 and the eccentric cam 4 does not decrease. As a result, it is possible to suppress the wear of the sliding contact portion between the link arm 5 and the eccentric cam 4 due to the decrease in the sliding contact area between the link arm 5 and the eccentric cam 4.

In addition, according to the present embodiment, even if the rocking cam 8 which does not normally fall down due to some cause (for example, overload), as described above, the rocker arm 14 does not fall. Does not come into contact with adjacent members (cam bracket 7, link arm 5).
No excessive stress is generated in the link mechanism L, and the durability of the link mechanism L is not impaired.

In this embodiment, the configuration in which the control shaft 12 is disposed above the camshaft 3 in FIG. 1 has been described. However, the present invention is not limited to this, and the control shaft 12 may be parallel to the camshaft 3. .

[Second Embodiment] FIG. 4 shows a second embodiment of the present invention and is a side view of a variable valve apparatus 1 for an internal combustion engine. In the present embodiment, as shown in FIG. 4, a thrust member 23 is arranged between one side surface 8e of the swing cam 8 and the cylinder head 2 and the cam bracket 7, and the swing cam 8, the cylinder head 2 Further, the wear of the cam bracket 7 is prevented, and the durability of the variable valve train 1 is further improved. Here, the thrust member 23 has a disk shape having a fitting hole 23a formed substantially at the center, and is fixed to the outer periphery of the camshaft 3. A gap L5 is formed between the side surface 8e of the swing cam 8 and the side surface 23b of the thrust member 23.

The gaps L2, L3, L4, L5 and the dimensions L1, ΔL1 are set so as to have the same relationship as in the first embodiment. Further, in the present embodiment, the configuration in which the thrust member 23 is disposed between the swing cam 8 and the cylinder head 2 and the cam bracket 7 has been described, but the thrust member 23 is disposed between the swing cam 8 and the eccentric cam 4. May be arranged, and a thrust member may be arranged on both sides 8e and 8f of the swing cam 8.

In each of the above embodiments, the variable valve operating device 1
Is shown on the intake valves 10 and 10 side, but may be installed on the exhaust valve side, or may be installed on both sides of the intake and exhaust valves.

[Brief description of the drawings]

FIG. 1 is a front view of a main part of a variable valve apparatus for an internal combustion engine according to a first embodiment of the present invention.

FIG. 2 is a plan view of a variable valve device of the internal combustion engine.

FIG. 3 is a side view of the variable valve device of the internal combustion engine.

FIG. 4 is a side view of a variable valve apparatus for an internal combustion engine according to a second embodiment of the present invention.

FIG. 5 is a plan view of a main part of a conventional variable valve apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Variable valve apparatus 2 ... Cylinder head (member) 3 ... Camshaft 4 ... Eccentric cam (member) 5 ... Link arm 5b ... Tip 7 ... Bracket (member) 8 ... Swing cam 8b ... Cam surface 8c ... Tip 8e , 8f ... side surface 10 ... intake valve 11 ... valve lifter 12 ... control shaft 14 ... rocker arm 14c ... one end 14d ... other end 15, 16, 18 ... pin 17 ... link member 23 ... thrust member

Continued on the front page (72) Inventor Keisuke Takeda 1370 Onna, Atsugi-shi, Kanagawa Pref.

Claims (3)

[Claims] 1. A camshaft that rotates in synchronization with rotation of an engine and has an eccentric cam on an outer periphery, a control shaft disposed parallel to the camshaft, and a rotation of the eccentric cam of the camshaft. A variable valve train for an internal combustion engine comprising: a link mechanism that operates in conjunction with the intake and exhaust valves to open and close intake and exhaust valves, wherein the link mechanism is rotatably fitted to the control shaft; A link arm rotatably fitted to the outer periphery of the eccentric cam of the camshaft and having a tip rotatably connected to one end of the rocker arm; and a link member rotatably connected to the other end of the rocker arm. A swinging cam having the other end swingably fitted to the outer periphery of the camshaft, the leading end pivotally connected to the link member, and having a cam surface slidingly contacting a valve lifter; The variable movement of the internal combustion engine is characterized in that movement of the link mechanism in the axial direction of the camshaft is regulated by abutting both side surfaces of the rocking cam orthogonal to the camshaft with adjacent members. Valve device. 2. The internal combustion engine according to claim 1, wherein a thrust member is arranged between at least one of the side surfaces of said swing cam orthogonal to said camshaft and said adjacent member. Variable valve gear. 3. The fitting surface width of the eccentric cam with the link arm is determined by the sum of the fitting surface width of the link arm with the eccentric cam and the moving amount of the link mechanism in the camshaft axial direction. 2. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the variable valve operating apparatus is increased.