JPH06207506A - Variable valve timing mechanism - Google Patents

Abstract

PURPOSE:To provide a more simple, lighter and reliable mechanism, in the variable valve timing mechanism of an internal combustion engine. CONSTITUTION:One T letter-shaped rocker arm 5 for low speed is and two or one rocker arm 8 for a high speed are installed in relation to two intake/ exhaust valves 4. Hydraulic pistons 14 supported by a hydraulic piston supporter 12 are installed in a rocker arm shaft 11 in their shapes crossing orthogonally to the central axis of the rocker arm shaft 11. There hydraulic pistons 14 are inserted in the inside of the rocker arm and/or returned back to the original positions by oil pressure. Consequently, the open/close timings of an intake/ exhaust valves 4 are switched by two steps like 'for low speed and for high speed'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a 4-cycle internal combustion engine.

[0002]

2. Description of the Related Art Among conventional four-cycle internal combustion engines, some types having a DOHC mechanism have a variable valve timing mechanism. This is a mechanism that makes it possible to achieve both high torque at low speed and high output at high speed by switching the opening / closing timing of the intake / exhaust valve (20) between low speed rotation and high speed rotation. . Of these, the one that is closely related to the present invention is that two types of cam pieces for low speed and high speed are arranged on the same cam shaft (9) and they are switched by a switching mechanism using the rocker arm (10). To do.

[0003]

By the way, the conventional variable valve timing mechanism of this kind has some problems. First, the rocker arm (1) has a switching mechanism incorporated therein.
0) has become heavier. This naturally means an increase in the weight of the valve opening / closing mechanism and deteriorates the followability of the mechanism when the engine rotates at high speed. Another problem is that reliability is deteriorated due to the complexity of the mechanism.

[0004]

In the present invention, in order to solve the above-mentioned drawbacks of the conventional variable valve timing mechanism, the rocker arm (10) switching mechanism is provided inside the rocker arm shaft (11). I decided to incorporate it in. FIG. 1 is a diagram showing a component structure of the invention of claim 1. Since the inventions of claims 1 and 2 have the same basic principle, the description will be focused on the invention of claim 1 in the meanwhile. As can be seen from FIG. 1, the rocker arm shaft (1
1) Inside, a hydraulic piston support (12), which is a cylindrical part, is incorporated. In FIG. 1, these parts are drawn so as to protrude from the rotary shaft portion of the rocker arm (10) in order to make the structure of the parts easy to understand. The hydraulic piston support (12) is connected to the T-shaped low speed rocker arm (5) by a connector (13). A hydraulic piston (14) is present inside the hydraulic piston support (12). In FIG. 1, the hydraulic piston (14) is also drawn to project from the hydraulic piston support (12) which is the mother body. Also from the same FIG. 1 it is shown that there is a hydraulic piston connecting slit (15) on the side surface of the rocker arm shaft (11). This slit is a hydraulic piston (1
4) is to prevent the movement of the rocker arm (10) when the rocker arm (10) moves. Also, FIG.
Rocker arm shaft (1
On the side opposite to 1), the connecting slit for connecting body (1
8) exists. The purpose of this slit is basically
It is the same as the purpose of the connecting slit (15) for the hydraulic piston. That is, when the connection body (13) moves with the movement of the rocker arm (10), it does not hinder the movement. The above is the rough part structure of the invention of claim 1.

[0005]

Next, please refer to FIG. 2 and FIG. These drawings show how the invention of claim 1 is actually incorporated and operated. From the viewpoint of the engine,
It is a viewpoint overlooking the rocker arm (10).
Of course, both figures are drawn through the internal structure that should not be seen. FIG. 2 shows the mode of the present invention when the engine is rotating at a low speed. In this state, no hydraulic pressure is applied behind the hydraulic piston (14). Therefore, the hydraulic piston (14) remains subsided from the surface of the rocker arm shaft (11). As a result, the hydraulic piston support (12)
And the high-speed rocker arm (8) operate independently of each other. Naturally, the hydraulic piston support (1
The low speed rocker arm (5), which is connected to 2) by the connecting body (13), also operates independently of the high speed rocker arm (8). As a result, the intake / exhaust valve (4) is driven by the T-shaped low speed rocker arm (5). And a rocker arm for high speed (8)
Only pushes the motion absorbing spring (7) and does not participate in opening and closing the intake / exhaust valve (4). Also, in FIG.
It shows the situation of the present invention when the engine is rotating at high speed. In this state, hydraulic pressure is applied behind the hydraulic piston (14). As a result, the hydraulic piston (1
While pushing the adjacent stopper pin (16), 2) protrudes from the surface of the rocker arm shaft (11) and enters the inside of the high speed rocker arm (8).
As a result, the hydraulic piston support (12) and the high speed rocker arm (8) operate in an interconnected manner. Naturally, the hydraulic piston support (12) and the connection (1
The low speed rocker arm (5) connected by 3) also operates in conjunction with the high speed rocker arm (8). As a result, the intake / exhaust valve (4) is directly pushed by the low speed rocker arm (5), but indirectly placed under the control of the high speed rocker arm (8). The above is the mechanism of the present invention. Also,
The invention of claim 2 will be briefly mentioned here. 4 to 6 are views showing the invention of claim 2. As can be seen from these figures, the invention of claim 2 is a variant of the claimed invention. FIG. 5 shows a low speed rotation state, and FIG. 6 shows a high speed rotation state. As can be seen from this, in the invention of claim 2, the hydraulic piston (14) enters the inside of the low speed rocker arm (5) by hydraulic pressure. The hydraulic piston support (12) is also connected to the high speed rocker arm (8) by a connection (13). The other operating principles are the same as the invention of claim 1.

[0006]

Embodiment 1 In FIGS. 2, 3, 5, and 6, the hydraulic piston (14) does not project into the oil passage hole (19). However, by extending this length, the hydraulic piston (1
It would be possible to have a structure in which 4) protrudes into the oil passage hole (19). Such a construction would eliminate the need for stoppers (20).

[0007]

Embodiment 2 In FIGS. 2, 3, 5, and 6, the width of the stopper pin (16) is wider than the width of the hydraulic piston (14) and the hydraulic piston connecting slit (15).
This is for preventing the stopper pin (16) from erroneously entering the hydraulic piston connecting slit (15). However, it would be possible to implement this width matching.

[0008]

As described above, by introducing the present invention, the rocker arm (1
0) Switching mechanism is rocker arm shaft (11)
Incorporated inside. As a result, the rocker arm (1
In 0), there was no need to incorporate a complicated mechanism, and the weight was significantly reduced. This will greatly improve the fast followability of the rocker arm (10). In addition, since the switching mechanism is simpler than before, the mechanism reliability is also improved.
It will be greatly improved.

[Brief description of drawings]

FIG. 1 is a component configuration diagram of the invention of claim 1.

FIG. 2 is a state when the engine of the invention of claim 1 is rotating at a low speed.

FIG. 3 is a state when the engine of the invention of claim 1 is rotating at high speed.

FIG. 4 is a component configuration diagram of the invention of claim 2;

FIG. 5 shows a state when the engine of the invention of claim 2 is rotating at a low speed.

FIG. 6 is a state when the engine of the invention of claim 2 is rotating at high speed.

[Explanation of symbols]

 1, intake valve 2, exhaust valve 3, cam piece with low speed cam profile 4, intake and exhaust valve 5, low speed rocker arm 6, cam piece with high speed cam profile 7, motion absorption spring 8, high speed rocker arm 9, Camshaft 10, rocker arm 11, rocker arm shaft 12, hydraulic piston support 13, connection body 14, hydraulic piston 15, hydraulic piston connecting slit 16, stopper pin 17, return spring 18, connecting body connecting slit 19 , Oil passage hole 20, stopper

Claims (2)

[Claims] 1. A 4-cycle internal combustion engine having a DOHC mechanism and having two intake valves (1) and two exhaust valves (2) per cylinder, (a) having a low speed cam profile There is one T-shaped low speed rocker arm (5) driven by the cam piece (3) and directly pushing the intake and exhaust valves (4), one for every two valves. (B) Driven by a cam piece (6) having a high speed cam profile and directly actuated by a motion absorbing spring (7).
Press one high speed rocker arm (8), one on each side of one low speed rocker arm (5), or
There is one low speed rocker arm (5) on each side. (C) The cam piece (3) having the low speed cam profile and the cam piece (6) having the high speed cam profile are present on the same cam shaft (9). Also, its placement corresponds to the position of the rocker arm (10) to be pushed. (D) Inside the rocker arm shaft (11), one cylindrical hydraulic piston support (12) is provided for a combination of a set of low speed rocker arm (5) and high speed rocker arm (8). Exists. This part is
3) connected to the low speed rocker arm (5). (E) The hydraulic piston (14) exists inside the hydraulic piston support (12). This hydraulic piston (14)
Slides in a direction perpendicular to the central axis of the rocker arm shaft (11) and enters or returns to the high speed rocker arm (8) through the hydraulic piston connecting slit (15). (F) Inside the high speed rocker arm (8), a stopper pin (16) and a return spring (17) are incorporated in order to correct the entry of the hydraulic piston (14). (G) Depending on the engine speed, the hydraulic piston (14)
The driving method of the T-shaped low-speed rocker arm (5) is switched between low-speed and high-speed by switching between applying and not applying hydraulic pressure to. A valve opening / closing mechanism for a four-cycle internal combustion engine having the above configuration. 2. The items (a) to (c) and (g) of the invention of claim 1 have common contents. Then, the items (d) to (f) have the following contents. (D) Inside the rocker arm shaft (11), one cylindrical hydraulic piston support (12) is provided for a combination of a set of low speed rocker arm (5) and high speed rocker arm (8). Exists. This part is
3) connected to the high speed rocker arm (8). (E) The hydraulic piston (14) exists inside the hydraulic piston support (12). This hydraulic piston (14)
Slides in a direction perpendicular to the central axis of the rocker arm shaft (11) and enters or returns to the low speed rocker arm (5) through the hydraulic piston connecting slit (15). (F) Inside the low speed rocker arm (5), a stopper pin (16) and a return spring (17) are incorporated in order to prevent the hydraulic piston (14) from entering. A valve opening / closing mechanism for a four-cycle internal combustion engine having the above configuration.