JPH06248919A - Variable valve timing mechanism - Google Patents

Abstract

PURPOSE:To provide a mechanism more simplified than a conventional one, reduce the weight and reduce the number of parts, and improve reliability in a variable valve timing mechanism having DOHC mechanism for a four-cycle internal combustion engine. CONSTITUTION:Two low speed rocker arms 5 and a high speed rocker arm 8 are arranged for two intake and exhaust valves 4. A hydraulic piston supporting shaft 11 is provided as a substitute for a rocker arm shaft, and a hydraulic piston 12 capable of sliding in the direction perpendicular to the center axis of the shaft is provided. The opening or closing timing of the intake and exhaust valves 4 is switched to low speed or high speed, namely two stages by entering the hydraulic piston into the rocker arms or returning it to its original position by means of oil pressure. Since the switching mechanism for the rocker arms is simplified, its weight is reduced, the number of parts is reduced, and its reliability can thus be improved.

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. Of these, the one closely related to the present invention is a switching mechanism using a rocker arm (10) in which two types of cam pieces for low speed and high speed are arranged on the same camshaft (9). It is a type of mechanism that tries to switch.

[0003]

The conventional mechanism of the same kind has some problems. The problem is that the rocker arm (10) switching mechanism is complicated and the number of parts is large. This causes an increase in weight, a complicated assembly process, and a decrease in reliability.

[0004]

In the present invention, in order to solve the above-mentioned drawbacks of the conventional variable valve timing mechanism, a hydraulic piston supporting shaft (11) is provided.
I decided to combine this with two low-speed rocker arms (5) and one high-speed rocker arm (8). FIG. 1 is a parts list of the invention of claim 1, and FIG. 2 is a perspective view of the invention of claim 1. As can be seen from these figures, in the invention of claim 1, there is a part called the hydraulic piston supporting shaft (11). This part replaces the conventional rocker arm shaft and has two low speed rocker arms (5).
And the rotation axis of one high-speed rocker arm (8). Further, this component is integrally molded with the low speed rocker arm (5) or fixed to the low speed rocker arm (5) in some form. Inside this part is a hydraulic piston (12). The hydraulic piston (12) has a shaft (11) for supporting the hydraulic piston.
While being supported by, it slides by hydraulic pressure and goes in and out of the high speed rocker arm (8). Also, inside the high speed rocker arm (8), a hydraulic piston (12) is provided.
Stopper pin (13) to catch the slide of
And a return spring (14) is present. In the parts list of Fig. 1, the high-speed rocker arm (8) is vertically
The hydraulic piston (12), the stopper pin (13), and the return spring (14) are divided into parts, and are drawn so as to project from their original positions. However, these parts are originally, as shown in FIG. 2, originally a shaft (11) for supporting a hydraulic piston and a rocker arm (8) for high speed.
It is something that is built in and exists inside.

[0005]

3 and 4 are views showing the operating condition of the invention of claim 1. FIG. 3 is a diagram when the engine is rotating at a low speed. In this case, the hydraulic piston (12) is inside the hydraulic piston supporting shaft (11). As a result, the low speed rocker arm (5) and the high speed rocker arm (8) operate independently of each other. As a result, the intake / exhaust valve (4) is driven by the low speed cam piece and opens and closes with the low speed cam profile. On the other hand, FIG.
[Fig. 4] is a diagram when the engine is rotating at high speed. In this case, the hydraulic piston (12) slides from the inside of the hydraulic piston supporting shaft (11) and enters the inside of the high speed rocker arm (8). Then, the stopper pin (13) and the return spring (14) are pushed and then stopped on the spot. As a result, the low-speed rocker arm (5) and the high-speed rocker arm (8) operate in conjunction with each other. 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), and the high speed cam piece is Will be driven by. As a result, intake and exhaust valves (4)
Will be opened and closed by the high speed cam profile. The above is the operating principle of the present invention. In addition, claim 2
I would like to briefly touch upon the invention of.
FIG. 5 to FIG. 8 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 invention of claim 1. 5 is a parts list, FIG. 6 is a perspective view, FIG. 7 is a view at low speed rotation, and FIG. 8 is a view at high speed rotation. As can be seen from here, claim 2
In the invention of (1), there are two hydraulic pistons (12) for one hydraulic piston supporting shaft (11). The hydraulic piston (12) then slides into the low speed rocker arm (5). The hydraulic piston supporting shaft (11) is integrally molded with the high speed rocker arm (5) or fixed in some form. The other operating principles are the same as the invention of claim 1.

[0006]

Embodiment 1 As mentioned above, FIGS. 1 to 4 are views of a typical embodiment of the invention of claim 1. FIG.

[0007]

[Embodiment 2] FIGS. 5 to 8 are views of a typical embodiment of the invention of claim 2.

[0008]

As described above, according to the present invention, the rocker arm (1
The switching mechanism of 0) was greatly simplified compared to the conventional mechanism, and the number of parts was greatly reduced. This is
It will bring advantages such as reducing the weight of the variable valve timing mechanism, simplifying the assembly process, and improving reliability.

[Brief description of drawings]

FIG. 1 is a parts list of the invention of claim 1.

FIG. 2 is a perspective view of the invention of claim 1; The upper part of the high speed rocker arm (8) has been removed to show the internal mechanism.

FIG. 3 is a perspective view of the invention of claim 1 when the engine is rotating at a low speed.

FIG. 4 is a perspective view of the invention of claim 1 when the engine is rotating at high speed.

FIG. 5 is a parts list of the invention of claim 2;

FIG. 6 is a perspective view of the invention of claim 2; The top of each rocker arm (10) has been removed to show the internal features.

FIG. 7 is a perspective view of the invention of claim 2 when the engine is rotating at a low speed.

FIG. 8 is a perspective view of the invention of claim 2 when the engine is rotating at a high speed.

[Explanation of symbols]

 1, intake valve 2, exhaust valve 3, low speed cam piece 4, intake and exhaust valve 5, low speed rocker arm 6, high speed cam piece 7, motion absorption spring 8, high speed rocker arm 9, camshaft 10, rocker arm 11, hydraulic piston support shaft 12, hydraulic piston 13, stopper pin 14, return spring

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) low speed cam piece (a) There is one low speed rocker arm (5) for each valve, driven by 3) and directly pushing the intake and exhaust valves (4). (B) A high speed rocker arm (8), which is driven by a high speed cam piece (6) and directly pushes a motion absorbing spring (7), is placed between two low speed rocker arms (5). There is one each. (C) The low speed cam piece (3) and the high speed cam piece (6) are
Present on the same camshaft (9). Also, its placement corresponds to the position of the rocker arm (10) to be pushed. (D) There is a cylindrical hydraulic piston supporting shaft (11) penetrating the rotation axis of the rocker arm (10). This shaft is for two low speed rocker arms (5) and one high speed rocker arm (8)
It is set one by one. This shaft operates integrally with the low speed rocker arm (5). (E) The hydraulic piston (12) exists inside the hydraulic piston supporting shaft (11). The hydraulic piston (12) slides in a direction orthogonal to the central axis of the hydraulic piston support shaft (11) and enters or returns to the inside of the high speed rocker arm (8). (F) Inside the high speed rocker arm (8), a stopper pin (13) and a return spring (14) are incorporated in order to prevent the hydraulic piston (12) from entering. A valve opening / closing mechanism for a four-cycle internal combustion engine having the above configuration. 2. The invention of claim 1 and the items (a) to (c) have common contents. The following points are different. (D) There is a cylindrical hydraulic piston supporting shaft (11) penetrating the rotation axis of the rocker arm (10). This shaft is for two low speed rocker arms (5) and one high speed rocker arm (8)
It is set one by one. This shaft operates integrally with the high speed rocker arm (8). (E) The hydraulic piston (12) exists inside the hydraulic piston supporting shaft (11). The hydraulic piston (12) slides in a direction orthogonal to the central axis of the hydraulic piston supporting shaft (11) and enters or returns to the inside of the low speed rocker arm (5). (F) Inside the low speed rocker arm (5), a stopper pin (13) and a return spring (14) are incorporated in order to prevent the hydraulic piston (12) from entering. A valve opening / closing mechanism for a four-cycle internal combustion engine having the above configuration.