JP2813709B2 - Variable valve timing mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Among conventional valve opening / closing mechanisms of a four-stroke internal combustion engine, a type having a DOHC mechanism or a SOHC mechanism has a variable valve timing mechanism. This is because the opening / closing timing of the intake valve (1) or the exhaust valve (2) is switched between when the engine is rotating at a low speed and when the engine is rotating at a high speed. This is a mechanism that attempts to achieve both. Among these mechanisms, the one that is closely related to the present invention is that two types of low-speed and high-speed cam pieces are arranged on the same camshaft (8) and are switched by a switching mechanism using a rocker arm. This is the type of mechanism that will be used.

[0003]

By the way, there are some problems in the conventional similar mechanism. The problem is that the mechanism for switching between the two types of cam pieces using the rocker arm is complicated, and the number of parts is large. This increases the weight of the valve opening / closing mechanism, complicates the assembling process, and lowers the reliability.

[0004]

SUMMARY OF THE INVENTION In the present invention, in order to solve the above-mentioned disadvantages of the conventional variable valve timing mechanism, a hydraulic piston supporting shaft (10) is provided.
And combined it with two low-speed rocker arms (4) and one high-speed rocker arm (7). 1 and 2 are parts lists according to the first embodiment of the present invention, which correspond to two intake valves (1) or two exhaust valves (2). FIGS. 3 and 4 are side cutaway views of the invention of claim 1 corresponding to two intake valves (1) or exhaust valves (2). In this case, FIG. 3 shows the case where the engine is rotating at a low speed, and FIG.
Shows the state of the invention of claim 1 when the engine is rotating at high speed. 5 and 6 are top perspective views of the invention according to claim 1, corresponding to two intake valves (1) or exhaust valves (2). In this case, FIG. 5 shows the state of the invention of claim 1 when the engine is rotating at low speed, and FIG. 6 shows the state when the engine is rotating at high speed. As can be seen from these drawings, the invention of claim 1 includes a component called a hydraulic piston support shaft (10). This part is present instead of a conventional rocker shaft and penetrates the rotating shaft portions of two low-speed rocker arms (4) and one high-speed rocker arm (7). Furthermore, this part is a rocker arm for low speed (4)
Or a part called a connector (9), or is integrally formed with the low-speed rocker arm (4). And inside this part there is a hydraulic piston (11). The hydraulic piston (11) slides by hydraulic pressure while being supported by the hydraulic piston support shaft (10), and moves in and out of the high-speed rocker arm (7). Also, inside the high-speed rocker arm (7),
A stopper pin (12) and a return spring (13) are provided to prevent the hydraulic piston (11) from sliding in and out.

[0005]

FIG. 3, FIG. 4, FIG. 5, and FIG. 6 are diagrams showing the operation of the first embodiment of the present invention. 3 and 5
Fig. 7 shows the state of the invention of claim 1 when the engine is rotating at a low speed. FIG. 3 is a side cutaway view of the invention of claim 1;
FIG. 5 is a top perspective view of the invention of claim 1 as viewed from above. From these figures, it can be seen that when the engine is rotating at low speed, the hydraulic piston (11) exists inside the hydraulic piston supporting shaft (10). As a result, the low speed rocker arm (4) and the high speed rocker arm (7) operate independently of each other. As a result, the intake valve (1) or the exhaust valve (2) is driven by the cam piece (3) having a low-speed cam profile and opens and closes at the low-speed cam profile. On the other hand, FIGS. 4 and 6 show the state of the invention of claim 1 when the engine is rotating at high speed. FIG. 4 is a side cutaway view of the first embodiment, and FIG. 6 is a top perspective view of the first embodiment as viewed from above. From these figures, when the engine is rotating at high speed, the hydraulic piston (11) slides from the hydraulic piston supporting shaft (10) and enters the inside of the high-speed rocker arm (7). Then, the stopper pin (12) and the return spring (13) are pressed and then stopped immediately. As a result, the low-speed rocker arm (4) and the high-speed rocker arm (7) operate in conjunction with each other. As a result of this,
The intake valve (1) or the exhaust valve (2) is directly pushed by the low speed rocker arm (4), but is indirectly under the control of the high speed rocker arm (7),
It is driven by a cam piece (5) having a high speed cam profile. As a result, the intake valve (1) or the exhaust valve (2) will open and close with a high speed cam profile. The above is the operation principle of the first aspect of the present invention. Here, the invention of claim 2 will be briefly described. FIGS. 11 to 16 show the second embodiment of the present invention. 11 and FIG.
FIG. 2 is a view showing parts constituting the second aspect of the present invention. With such a group of components, it is responsible for opening and closing two valves on either the intake side or the exhaust side of one cylinder. As can be seen from these figures, the invention of claim 2 is a variation of the invention of claim 1. FIG. 13 and FIG.
5 shows a state in which the engine is running at low speed, and FIGS.
Reference numeral 6 denotes a state where the engine is rotating at high speed. As can be seen from the above, in the invention of claim 2, one hydraulic piston supporting shaft (10) has two hydraulic pistons (11). Then, these hydraulic pistons (11) enter the inside of the low-speed rocker arm (4) by hydraulic pressure. This is opposite to the case where the hydraulic piston (11) according to the first aspect of the present invention enters the high-speed rocker arm (7). The hydraulic piston supporting shaft (10) is connected to the high-speed rocker arm (7) by a connector (9). This is also opposite to the case where the hydraulic piston supporting shaft (10) of the first aspect is connected to the low speed rocker arm (4).
The other operation principle is the same as that of the first aspect.

[0006]

7 and 8 show a first embodiment of the present invention.
An embodiment in the case where the present invention is applied to a C in-line four-cylinder engine is shown. What is illustrated here is an arrangement diagram of a rocker arm group and associated parts group for four cylinders. 7 shows a case where the engine is rotating at a low speed, and FIG. 8 shows a case where the engine is rotating at a high speed. From this figure, it can be seen that the present embodiment employs an inner fulcrum type rocker arm. In these figures, the parts in the left column of the figures are perspective views so that the internal structure can be understood. As can be seen from these drawings, in the invention of claim 1, there is no rocker shaft that bundles the rocker arm groups in one row.
Instead, there is a component called a hydraulic piston support shaft (10). The rocker arm group rotates with this part as a rotation axis while being fixed to the cylinder head by a rocker arm holder (not shown). FIG. 9 is a side cutaway view of a cylinder and a cylinder head of an engine according to the first embodiment of the present invention. In this example, it can be understood from the figure that an inner fulcrum type rocker arm in which the rotation axis of the rocker arm is inside the camshaft (8) is introduced. Further, FIG.
FIG. 2 is a side cutaway view of a cylinder and a cylinder head of an engine, showing another embodiment of the invention of claim 1. In this example, unlike the case of FIG. 9, it can be understood that a rocker arm of an external fulcrum type in which the rotation axis of the rocker arm is outside or directly below the camshaft (8) is introduced. 17 and FIG.
Shows an embodiment in which the invention of claim 2 is applied to a DOHC in-line four-cylinder engine. What is illustrated here is an arrangement diagram of a rocker arm group and associated parts group for four cylinders. FIG. 17 shows a case where the engine is rotating at a low speed, and FIG. 18 shows a case where the engine is rotating at a high speed. FIG. 19 is a side cutaway view of a cylinder and a cylinder head of an engine according to the second embodiment of the present invention. In this example, an inner fulcrum type rocker arm is introduced. FIG. 20 is a side cutaway view of a cylinder and a cylinder head of an engine according to another embodiment of the present invention. In this example, a rocker arm of an external fulcrum type is introduced.

[0007]

As described above, according to the present invention, the switching mechanism of the rocker arm in the variable valve timing mechanism is greatly simplified as compared with the conventional similar type mechanism.
The number of parts has been significantly reduced. This means that the present invention has significantly reduced the weight of the valve train in such a variable valve timing mechanism. Also, in the present invention, it means that the assembling process is greatly simplified and the reliability is improved as compared with the conventional similar mechanism.

[Brief description of the drawings]

FIG. 1 is a parts list for three rocker arms according to the invention of claim 1; These components are responsible for opening and closing two valves on either the intake side or the exhaust side of one cylinder.

FIG. 2 is a parts list for three rocker arms according to the invention of claim 1; The viewing angle is different from FIG. These components are responsible for opening and closing two valves on either the intake side or the exhaust side of one cylinder.

FIG. 3 is a side cutaway view of the invention according to claim 1; When the engine is running at low speed.

FIG. 4 is a side cutaway view of the invention according to claim 1; When the engine is running at high speed.

FIG. 5 is a top perspective view of three rocker arms according to the first embodiment of the present invention. When the engine is running at low speed.

FIG. 6 is a top perspective view of three rocker arms according to the first embodiment of the present invention. When the engine is running at high speed.

FIG. 7 is an arrangement diagram of a rocker arm group and associated parts group when the invention of claim 1 is applied to a DOHC in-line four-cylinder engine. When the engine is running at low speed.

FIG. 8 is an arrangement diagram of a rocker arm group and an associated component group when the invention of claim 1 is applied to a DOHC in-line four-cylinder engine. When the engine is running at high speed.

FIG. 9 is a side cutaway view of the engine showing one embodiment of the invention of claim 1; When the rocker arm uses the inner fulcrum method.

FIG. 10 is a side cutaway view of an engine showing one embodiment of the invention of claim 1; When the rocker arm is an external fulcrum method.

FIG. 11 is a parts list for three rocker arms according to the invention of claim 2; These components are responsible for opening and closing two valves on either the intake side or the exhaust side of one cylinder.

FIG. 12 is a parts list for three rocker arms according to the invention of claim 2; The viewing angle is different from FIG. These components are responsible for opening and closing two valves on either the intake side or the exhaust side of one cylinder.

FIG. 13 is a side cutaway view of the invention of claim 2; When the engine is running at low speed.

FIG. 14 is a side cutaway view of the invention of claim 2; When the engine is running at high speed.

FIG. 15 is a top perspective view of three rocker arms according to the invention of claim 2; When the engine is running at low speed.

FIG. 16 is a top perspective view of three rocker arms according to the invention of claim 2; When the engine is running at high speed.

FIG. 17 is an arrangement diagram of a rocker arm group and associated parts group when the invention of claim 2 is applied to a DOHC in-line four-cylinder engine. When the engine is running at low speed.

FIG. 18 is an arrangement diagram of a rocker arm group and associated parts group when the invention of claim 2 is applied to a DOHC in-line four-cylinder engine. When the engine is running at high speed.

FIG. 19 is a side cutaway view of an engine showing one embodiment of the invention of claim 2; When the rocker arm uses the inner fulcrum method.

FIG. 20 is a side cutaway view of an engine showing one embodiment of the invention according to claim 2; When the rocker arm is an external fulcrum method.

[Explanation of symbols]

 1, intake valve 2, exhaust valve 3, cam piece with low speed cam profile 4, rocker arm for low speed 5, cam piece with high speed cam profile 6, motion absorbing spring 7, rocker arm for high speed 8, cam shaft 9, connection Body 10, hydraulic piston support shaft 11, hydraulic piston 12, stopper pin 13, return spring

Claims (2)

(57) [Claims] 1. A four-stroke internal combustion engine having a DOHC mechanism and having two intake valves (1) and two exhaust valves (2) per cylinder. A low-speed rocker arm (4), driven by a cam piece (3) and directly pressing an intake valve (1) or an exhaust valve (2), for one intake valve (1) or exhaust valve (2). ,
There is one by one. (B) A motion absorbing spring (6) driven by a cam piece (5) having a high-speed cam profile and directly.
, There is one high-speed rocker arm (7) between the two low-speed rocker arms (4). (C) The cam piece (3) having the low-speed cam profile and the cam piece (5) having the high-speed cam profile exist on the same camshaft (8). Also, the arrangement corresponds to the position of the rocker arm to be pushed. (D) There is a cylindrical hydraulic piston supporting shaft (10) penetrating the rotation axis of each rocker arm group. This shaft has two rocker arms for low speed (4) and one rocker arm for high speed (7)
There is one. The shaft is connected to the low-speed rocker arm (4) by a connector (9) or is integrally formed with the low-speed rocker arm (4) to be integrated with the low-speed rocker arm (4). Work. (E) A hydraulic piston (11) exists inside the hydraulic piston support shaft (10). This piston slides in a direction perpendicular to the center axis of the hydraulic piston supporting shaft (10) by being subjected to hydraulic pressure from behind, and enters into the high-speed rocker arm (7) or returns to its original position. Or By this slide, the opening / closing timing of the intake valve (1) or the exhaust valve (2) is switched between two stages for low speed and high speed. (F) A stopper pin (12) and a return spring (13) are incorporated in the inside of the high-speed rocker arm (7) to prevent the hydraulic piston (11) from entering. The four-stroke internal combustion engine having the above configuration,
Valve opening and closing mechanism. 2. A four-stroke internal combustion engine having a DOHC mechanism and having two intake valves (1) and two exhaust valves (2) per cylinder. A low-speed rocker arm (4), driven by a cam piece (3) and directly pressing an intake valve (1) or an exhaust valve (2), for one intake valve (1) or exhaust valve (2). ,
There is one by one. (B) A motion absorbing spring (6) driven by a cam piece (5) having a high-speed cam profile and directly.
, There is one high-speed rocker arm (7) between the two low-speed rocker arms (4). (C) The cam piece (3) having the low-speed cam profile and the cam piece (5) having the high-speed cam profile exist on the same camshaft (8). Also, the arrangement corresponds to the position of the rocker arm to be pushed. (D) There is a cylindrical hydraulic piston supporting shaft (10) penetrating the rotation axis of each rocker arm group. This shaft has two rocker arms for low speed (4) and one rocker arm for high speed (4),
There is one. The shaft is connected to the high-speed rocker arm (7) by a connector (9) or is integrally formed with the high-speed rocker arm (7) to be integrated with the high-speed rocker arm (7). Work. (E) A hydraulic piston (11) exists inside the hydraulic piston support shaft (10). This piston slides in a direction perpendicular to the center axis of the hydraulic piston supporting shaft (10) when hydraulic pressure is applied from behind, and enters into the low-speed rocker arm (4) or returns to the original position. Or By this slide, the opening / closing timing of the intake valve (1) or the exhaust valve (2) is switched between two stages for low speed and high speed. (F) A stopper pin (12) and a return spring (13) are incorporated in the inside of the low-speed rocker arm (4) to receive the hydraulic piston (11). The four-stroke internal combustion engine having the above configuration,
Valve opening and closing mechanism.