JP3357459B2 - Engine Valve Actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve operating device for an engine, and more particularly, to a valve operating device for an engine that changes the operating mode of an intake valve or an exhaust valve in accordance with an operating state of the engine.

[0002]

2. Description of the Related Art Conventionally, in order to achieve both high torque characteristics at low and medium speed operation and improvement of output at high speed operation, lift characteristics of an intake valve or an exhaust valve are varied according to an operation state. It is known to control the intake / exhaust timing or intake / exhaust amount (for example, see Japanese Unexamined Patent Publication No.
171909).

In the conventional example disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 5-171909, a first rocker arm having one end abutting on a valve stem and driven by a low-speed cam is rotatably supported by the first rocker arm and has a high speed. And a second rocker arm driven by the cam. In addition, the first rocker arm has
A lever member that engages with the second rocker arm and switches between a position where the first rocker arm and the second rocker arm are connected and a position where both are disengaged is rotatably supported. By switching the rotation position of the lever member with a hydraulically operated plunger, the operation mode of the intake valve or the exhaust valve is changed.

[0004]

However, in the above-mentioned conventional example, the connection state or the non-connection state of the first and second rocker arms is obtained by switching the rotation position of the lever member. Therefore, the following problem may occur. That is, for example, when a command to switch from the low-speed cam operation state to the high-speed cam operation state is issued in accordance with a change in the operation state of the engine, the lever member switches from the non-connection state position to the connection state position in response to this command. The lever member and the second rocker arm are partially engaged in the lift section of the high-speed cam during the rotation. When the lift is further performed by the high-speed cam in such a state, a moment acts on the lever member around the center of rotation, but this moment acts in the direction to rotate the lever member in the reverse direction. A phenomenon occurs in which the lever member is flipped with the increase. When the lever member is flipped in the middle of its rotation, the high-speed cam shifts from the high-lift state to the low-speed cam and the low-lift state. There was a risk of occurrence.

An object of the present invention is to pay attention to the above-mentioned conventional problems, and to solve the problems, to prevent disengagement during switching and to maintain a stable coupling state of an engine valve. It is to provide a device.

[0006]

In order to achieve the above object, the present invention is directed to a main rocker shaft which is swingably supported and driven by a first cam, and a tip end of which is a head of an intake valve or an exhaust valve. A first rocker arm slidably contacting the first rocker arm;
A second rocker arm that is swingably supported by the rocker arm or the main rocker shaft and is driven by an acting force applied from a second cam coaxial with the first cam; and is rotatably supported by the first rocker arm. A switching member for switching the second rocker arm between the first rocker arm and the first rocker arm in a coupled state and a non-coupled state. The arrangement is made such that the normal line of the mating surface is located on the swing center side of the second rocker arm with respect to a line segment connecting the engagement position and the rotation center of the switching member. It is.

[0007]

According to the present invention, the switching member is rotated, and
Even if the second rocker arm and the switching member are in a partially engaged state, the normal line of both engagement surfaces at the engagement position of the two is a line segment connecting the engagement position and the rotation center of the switching member. On the other hand, since it exists on the swing center side of the second rocker arm,
The moment acting on the switching member acts in the rotation direction in which the switching member is further in the fully engaged state, and the disengagement of the switching member is prevented.

[0008]

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

1 to 5 show one embodiment of the present invention.

In this embodiment, the present invention is applied to an engine provided with two valves (either an intake valve or an exhaust valve, the illustrated one being an intake valve) having the same function for one cylinder. The example in the case of applying is shown. That is, each cylinder is provided with a single main rocker arm (first rocker arm) 1 corresponding to two intake valves 2, and the base end of the main rocker arm 1 is a hollow main rocker shaft 3 common to each cylinder. The main rocker arm 1 has a bifurcated distal end 1A abutting on the top of the stem 2A of the intake valve 2 via a cylinder head (not shown).

The main rocker arm 1 is formed substantially bifurcated in plan view, and a low-speed cam follower 4 is provided substantially at the center of each of the arms 1F, 1F formed bifurcated of the main rocker arm 1.

Reference numeral 5 denotes a sub rocker arm (second rocker arm) which is swingably supported by a support shaft 6 above a crotch formed in the fork of the main rocker arm 1. High speed cam follower. The high-speed cam follower 7 and the two low-speed cam followers 4 are arranged in the axial direction of the cam shaft 8 as shown in FIGS. 9 and 10 are a high-speed cam and a low-speed cam formed integrally with the cam shaft 8, and the high-speed cam follower 7 and the low-speed cam follower 4
The low-speed cam 10 is driven by sliding contact with the low-speed cam 10.

Reference numeral 11 denotes a lever member, which is shown in FIGS.
As shown in the figure, the lever support shaft 12 of the main rocker arm 1
It is supported swingably. Reference numeral 13 denotes an engagement surface provided at one end of the lever member 11, and the engagement surface 13 is rotated by rotating the lever member 11 as described later so that the engagement surface 13 is engaged with the engagement surface 5A of the sub rocker arm 5 (see FIG. 4). ), The sub rocker arm 5 and the main rocker arm 1 are maintained in a connected state, and the high-speed cam 9 is moved through the high-speed cam follower 7.
Can be transmitted to the intake valve 2. (Active state of high-speed cam follower 7) Next, a high-low speed switching mechanism according to the present invention will be described with reference to FIG.

FIGS. 4A and 4B show a low-speed operation state, and FIG. 4C shows a high-speed operation state. 4, 5B is a first plunger storage hole drilled in the sub rocker arm 5, 1B is a second plunger storage hole drilled in the main rocker arm 1, and 1C shown in FIG. 3 is a third plunger storage hole formed in the hole. 21 is a first plunger slidably fitted in the first plunger housing hole 5B,
A spring 22 biases the distal end of the first plunger 21 toward the butting portion 1D of the main rocker arm 1.
Reference numeral 3 denotes a stopper ring that regulates the stroke of the first plunger 21, and reference numeral 24 denotes an air vent.

On the other hand, an oil passage 25 for guiding oil from an oil passage 3A provided at the center of the rocker shaft 3 communicates with the second plunger housing hole 1B, and is slidably held in the housing hole 1B. By causing the second plunger 26 to protrude toward the operating end 11B of the lever member 11 as shown in FIG.
Can be engaged with the engagement surface 5A of the sub rocker arm 5. 4B is a third plunger slidably held in the third plunger housing hole 1C, and 28 is a projection 11A (see FIG. 1) in which the third plunger 27 is provided on the lever member 11. The spring is biased toward.

Next, the valve operation at high speed and at low speed according to the present embodiment will be described with reference to FIGS.

When the vehicle is in a low speed state as shown in FIGS. 4A and 4B, the hydraulic pressure is not supplied to the second plunger 26 via the oil passage 3A of the rocker shaft 3. Instead, the lever member 11 is maintained in the clockwise rotated position by the third plunger biased by the spring 28 as shown in FIG. Thus, the swinging of the sub rocker arm 5 is allowed, and even if the high-speed cam 9 slides on the high-speed cam follower 7, the first plunger 21 and the spring 22 only absorb the cam profile of the high-speed cam 9 and the valve shaft is closed. The lift by the high-speed cam 9 is not transmitted to 2 A, and the low-speed cam 10 slides on the low-speed cam follower 4.
Of the valve shaft 2A performs a lift operation (see FIG. 3).

At the time of high speed, a control unit (not shown)
Oil passage 3 of rocker shaft 3 via hydraulic supply means
A through the oil passage 25 to the second plunger housing hole 1
4B, the second plunger 26 protrudes from the second plunger storage chamber 1B as shown in FIG. 4C and acts on the operating end 11B of the lever member 11. The member 11 is rotated in a counterclockwise direction. In this case, the lever member 11 operates to push the third plunger 27 back into the third plunger housing hole 1C against the spring force of the spring 28, and the engagement surface 1
3 is engaged with the engagement surface 5A of the sub rocker arm 5.

Subsequently, the valve operating device having the above-described structure prevents the lever member 11 from being disengaged in the middle of the rotation, so that the rocker arms are always connected stably, that is, the valve opening operation at high speed is performed. The conditions will be described.

In the valve operating device according to the structure of the present invention, the second plunger 26 is operated by hydraulic pressure, and the lever member 1 is moved.
1 is rotated about the rotation center P of the lever support shaft 12 so that its engagement surface 13 is engaged with the engagement surface 5A of the sub rocker arm 5. Thus, in the case of the present invention, as shown in FIG. 5, when partially engaged, the acting force for valve opening transmitted to the cam follower 7 of the sub rocker arm 5 via the high speed cam 9 is applied to the engagement surface of the rocker arm 5. 5A is transmitted to the engaging surface 13 of the lever member 11 as a pressing force, and the shape of the two engaging surfaces 5A and 13 is determined by the relationship between the engaging surface 5A of the sub rocker arm 5 and the engaging surface 13 of the lever member 11. In the joint device Q, a normal line N of both engagement surfaces is a line segment PQ connecting the engagement position Q and the rotation center P of the lever member 11,
The sub rocker arm 5 is arranged so as to be present on the side of the swing center (support shaft 6) of the sub rocker arm 5.

Thus, since the direction of the pressing force exists in the further rotating direction of the lever member 11 with respect to the line segment PQ, a moment acts on the lever member 11 in the rotating direction in which the lever member 11 is fully engaged. That is, the lever member 11 is not repelled by the sub rocker arm 5 even when it is partially engaged, and the engagement is not released.

In this embodiment, the main rocker arm 1
Although the apparatus in which the sub rocker arm 5 is pivotally supported is described above, it goes without saying that the present invention can also be applied to an apparatus in which the main rocker arm and the sub rocker arm swing coaxially.

[0023]

As described above, according to the present invention, the first rocker shaft is pivotably supported on the main rocker shaft.
A first rocker arm driven by a cam and having a leading end slidably in contact with a head of an intake valve or an exhaust valve; and a second rocker supported by the first rocker arm or the main rocker shaft to be swingable and coaxial with the first cam. A second rocker arm driven by an acting force applied from a cam; and a switching member rotatably supported by the first rocker arm and capable of switching the second rocker arm to a connected state and a non-coupled state with the first rocker arm. A line segment connecting the engagement surface and the rotation center of the switching member when the second rocker arm and the switching member are engaged with each other. On the other hand, since the second rocker arm is arranged so as to be located on the swing center side, even if the valve opening operation is performed in an incompletely connected state at the time of engagement, Engaging the edge of switching member is prevented from occurring can be made stable opening operation, it is possible to prevent generation of impact sound.

[Brief description of the drawings]

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

FIG. 2 is a top view excluding the cam device of the embodiment shown in FIG.

FIG. 3 is a front view of the embodiment shown in FIG. 1;

FIG. 4 is a sectional view taken along the line AA in FIG. 2 and FIG. 1B along the line BB in FIG. 1 showing a valve operating state at the time of a low lift according to the embodiment shown in FIG. Fig. 2
It is explanatory drawing shown by the AA line sectional drawing (C) of FIG.

FIG. 5 is an explanatory diagram showing a relationship between a normal line N and a line segment PQ of an engagement surface at the time of partial engagement in the embodiment shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main rocker arm (1st rocker arm) 2 (Intake) valve 3 Rocker shaft 5 Sub rocker arm (2nd rocker arm) 5A Engagement surface 6 Support shaft 8 Cam shaft 9 High speed cam 10 Low speed cam 11 Lever member 12 Lever support shaft 13 Engage surface

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01L 13/00 301 F01L 1/26

Claims (1)

(57) [Claims] A first rocker arm that is swingably supported by a main rocker shaft, is driven by a first cam, and has a leading end slidably in contact with a head of an intake valve or an exhaust valve; and the first rocker arm or the main rocker. A second rocker arm pivotally supported by a shaft and driven by an acting force applied from a second cam coaxial with the first cam; a second rocker arm rotatably supported by the first rocker arm;
A switching member for switching the rocker arm between the first rocker arm and the coupled state and the non-coupled state, wherein when the second rocker arm and the switching member are engaged, the engagement surface at the engagement position of the two A valve operating device for an engine, wherein a line is arranged so as to be located on the swing center side of the second rocker arm with respect to a line segment connecting the engagement position and the rotation center of the switching member. .