JP4084542B2 - Variable valve mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable valve mechanism that changes a lift amount and a working angle of a valve continuously or stepwise in accordance with an operating state of an internal combustion engine.
[0002]
[Prior art]
Since the normal valve mechanism does not change the lift amount or operating angle of the valve even if the operating status of the internal combustion engine changes, it must balance various characteristics such as the output of the internal combustion engine, torque, fuel consumption, and exhaust gas cleanliness. I can't. In view of this, various variable valve mechanisms for changing the valve lift or operating angle continuously or stepwise in accordance with the operating conditions of the internal combustion engine have been conventionally considered.
[0003]
[Problems to be solved by the invention]
However, conventional low-stage variable type valve mechanisms, such as those that change in two or three stages in the low and high rotation range of an internal combustion engine, can not be precisely controlled over the entire operating situation, switching There are problems such as valleys in torque characteristics at points, and difficulty in improving reliability. Further, the conventional continuously variable type valve operating mechanism has a problem that only one of the lift amount and the working angle of the valve can be changed or it is difficult to improve the reliability.
[0004]
Therefore, the object of the present invention is to solve the above-mentioned problems, change the valve lift and operating angle continuously or stepwise over the entire operating state of the internal combustion engine, and perform precise control and have a simple structure. An object of the present invention is to provide a variable valve mechanism that can obtain high reliability.
[0005]
[Means for Solving the Problems]
To achieve the above object, the variable valve mechanism of the present invention is to press the first rotating cam the cam corresponding portion of the rocker arm, the swing center of the rocker arm via the A Justa first rotary cam and The valve is lifted by a second rotating cam rotating at the same rotational speed, and the phase of the second rotating cam with respect to the first rotating cam is changed continuously or stepwise according to the operating condition of the internal combustion engine. And a phase change device for changing the working angle , wherein the adjuster includes a first member and a second member engaged with each other so as to be able to contact and separate, and a lost member for urging the first member and the second member in the separating direction. It includes a motion spring .
[0006]
Here, the rocker arm may be any of the following types. In addition, a cam corresponding | compatible part means the site | part pressed corresponding to a cam.
(1) A type (a so-called swing arm) in which a rocker arm has a rocking center at one end, a cam corresponding portion at the center, and a valve pressing portion at the other end.
(2) Type that has a rocking center at the center of the rocker arm, a cam corresponding part at one end, and a valve pressing part at the other end.
[0007]
The following two modes can be exemplified as the swing center portion.
(A) A mode in which the swinging center portion is a concave spherical surface portion supported by a pivot, and an adjuster is connected to the pivot.
(B) A mode in which the rocking center portion is a shaft hole portion rotatably supported by the rocker shaft, and an adjuster is connected to the rocker shaft.
[0008]
Structure of the adjuster is not particularly limited, yo Ri specifically, the inner primary member and the outer second member cupped the side wall is engaged with the inside and outside to face the open side to each other, the inner first member And a coil spring as a lost motion spring installed in a compressed state between the inner bottom surface of the cup and the inner bottom surface of the outer second member.
[0009]
It is preferable that a tappet clearance adjusting mechanism using a screw is provided between the swing center portion and the adjuster. For example, in the above-described aspect (a), a tappet clearance adjustment mechanism in which a male screw provided on a pivot is screwed into a female screw provided on an adjuster so that the screwing amount can be adjusted can be exemplified.
[0010]
Although it does not specifically limit as a phase change apparatus, The thing provided with the helical spline mechanism, the drive part using hydraulic_pressure | hydraulic, and control apparatuses, such as a microcomputer, can be illustrated.
[0011]
The variable valve mechanism of the present invention can be applied to either the intake valve or the exhaust valve, but is preferably applied to both.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a variable valve mechanism that embodies the present invention will be described below with reference to FIGS. As this variable valve mechanism, a swing arm type rocker arm 1 is used, and one end portion of the rocker arm 1 is supported by a pivot 3 with a concave spherical surface portion 2 formed in the same portion, and serves as a rocking center portion. A roller arrangement hole 4 formed in the central portion of the rocker arm 1 is provided with a roller 5 and is rotatably mounted on the side wall of the arm. A portion of the roller 5 protruding upward from the upper surface of the arm is a cam corresponding portion. It has become. The other end of the rocker arm 1 is divided into two forks, and a valve pressing portion 6 that presses the valve 9 is formed at the lower end of each tip.
[0013]
In this embodiment, the roller 5 which is the cam corresponding portion of the rocker arm 1 is pressed by the first rotating cam 7, and the pivot 3 which is the rocking center portion of the rocker arm 1 is pressed by the second rotating cam 8 via the mechanical adjuster 10. I try to press it. Further, the phase of the second rotary cam 8 with respect to the first rotary cam 7 is changed continuously or stepwise (preferably in three or more stages) according to the operating condition of the internal combustion engine, so that the valve lift and operating angle are changed. A phase change device (not shown) for changing is provided.
[0014]
The mechanical adjuster 10 includes a cup-shaped inner first member 11 and an outer second member 12 whose side peripheral walls engage with each other so that they can be brought into contact with and separated from each other with the opening sides facing each other, and the inside of the cup of the inner first member 11. A coil spring as a lost motion spring 13 that is installed in a compressed state between the bottom surface and the inner bottom surface of the cup of the outer second member 12 and biases the inner first member 11 and the outer second member 12 in the separating direction. The outer second member 12 is guided by the guide hole 15 of the cylinder head 14 and slides.
[0015]
A male screw provided at the lower portion of the pivot 3 is screwed into a female screw provided on the cup end wall of the inner first member 11 of the mechanical adjuster 10 so that the screw amount can be adjusted, thereby constituting a tappet clearance adjusting mechanism. ing.
[0016]
The first rotating cam 7 includes a base circle 7a, a nose gradually increasing portion 7b in which the protruding amount gradually increases, a nose 7c that continues at a wide angle with substantially the same protruding amount, and a nose gradually decreasing portion 7d in which the protruding amount gradually decreases. It is rotatably supported above 5 and is in sliding contact with the roller 5.
[0017]
The second rotating cam 8 includes a base circle 8a, a nose gradually increasing portion 8b in which the protruding amount gradually increases, a nose 8c that continues at a wide angle with substantially the same protruding amount, and a nose gradually decreasing portion 8d in which the protruding amount gradually decreases. It is rotatably supported below the adjuster 10 so as to be in sliding contact with the cup end wall of the outer second member 12.
[0018]
The phase change device is configured such that a piston provided with a helical spline moves in the axial direction while rotating at a predetermined angle by hydraulic pressure, and the rotation acts on the second rotary cam 8, whereby the second rotary cam with respect to the first rotary cam 7. 8 is configured to change the phase, and is controlled by a control device such as a microcomputer based on a detection value from a rotation sensor or an accelerator opening sensor of the internal combustion engine.
[0019]
The variable valve mechanism configured as described above operates as follows.
First, FIG. 2 (a) → (b) → FIG. 3 (a) → (b) shows the first rotating cam 7 set by the phase change device in an operating condition where the maximum lift amount and the maximum operating angle are required. The phase relationship of the 2nd rotation cam 8 with respect to and the effect | action by it are shown.
As shown in FIG. 2A, when the front half of the base circle 7 a of the first rotating cam 7 is in sliding contact with the roller 5, the latter half of the base circle 8 a of the second rotating cam 8 is in sliding contact with the mechanical adjuster 10. At this time, since the lost motion spring 13 separates the inner first member 11 and the outer second member 12 to extend the mechanical adjuster 10, it is possible to prevent gaps from being formed in each part, thereby preventing the rocker arm 1 from falling.
As shown in FIG. 2 (b), when the rear half of the base circle 7 a is in sliding contact with the roller 5, the nose gradually increasing portion 8 b or the front half of the nose 8 c is in sliding contact with the mechanical adjuster 10. At this time, in the mechanical adjuster 10, the lost motion spring 13 is compressed and the extension is contracted, and the inner first member 11 and the outer second member 12 only come into contact with each other (bottomed), so that the lift amount of the valve 9 is still generated. do not do.
As shown in FIG. 3A, when the front half of the nose gradually increasing portion 7 b or the nose 7 c is in sliding contact with the roller 5, the rear half of the nose 8 c is in sliding contact with the mechanical adjuster 10. At this time, the lift amount L of the valve 9 is generated and increased to reach the maximum value Lmax, and the operating angle is also maximized (see FIG. 6).
As shown in FIG. 3B, when the rear half of the nose 7 c is in sliding contact with the roller 5, the nose gradually decreasing portion 8 d or the front half of the base circle 8 a is in sliding contact with the mechanical adjuster 10. At this time, since the mechanical adjuster 10 in the contracted state descends in the guide hole 15 and the pivot 3 is lowered, the lift amount L of the valve 9 is reduced to zero.
[0020]
Next, FIG. 4 (a) → (b) shows the phase relationship of the second rotary cam 8 with respect to the first rotary cam 7 set by the phase change device under an operating condition that requires a small lift amount and a small working angle. And the effect by it is shown.
As shown in FIG. 4A, when the initial portion of the nose gradually increasing portion 7b to the nose 7c is in sliding contact with the roller 5 to increase the lift amount of the valve, the nose gradually decreasing portion 8d is in sliding contact with the mechanical adjuster 10. Since the pivot 3 starts to be lowered, both the lift amount L and the operating angle of the valve 9 become very small (see FIG. 6).
As shown in FIG. 4B, as soon as the sliding contact of the nose 7c to the roller 5 proceeds, the base circle 8a slides on the mechanical adjuster 10 and lowers the pivot 3.
[0021]
2 and 3 and FIG. 4, the second rotation of the first rotation cam 7 between FIG. 2, FIG. 3 and FIG. 4 is intermediate. The phase relationship of the cam 8 is set continuously or stepwise by the phase change device, and an intermediate lift amount / working angle is obtained continuously or stepwise as shown in FIG.
[0022]
Next, FIG. 5 (a) → (b) shows the phase relationship of the second rotating cam 8 with respect to the first rotating cam 7 and the action caused by the phase changing device, which is set by the phase changing device in an operating situation where lift stop is necessary. Show.
As shown in FIG. 5A, before the nose gradually increasing portion 7b is brought into sliding contact with the roller 5, the nose gradually decreasing portion 8d is brought into sliding contact with the mechanical adjuster 10 and starts to lower the pivot 3, so that the lift amount L and the action of the valve 9 are increased. Both corners are 0, and the lift is stopped.
As shown in FIG. 5B, even when the nose 7c starts to slide on the roller 5, the valve 9 does not lift because the base circle 8a slides on the mechanical adjuster 10 to lower the pivot 3.
[0023]
In addition, this invention is not limited to the structure of the said embodiment, For example, as follows, it can also change and actualize in the range which does not deviate from the meaning of invention.
(1) Do not place a mechanical adjuster 10 between the pivot 3 and the second rotary cam 8.
(2) Change the configuration and control method of the phase change device as appropriate.
(3) The rocker arm 1 should have a rocking center at the center.
[0024]
【The invention's effect】
Since the variable valve mechanism of the present invention is configured as described above, the valve lift amount and operating angle can be changed continuously or stepwise over the entire operating state of the internal combustion engine, and precise control can be performed. There is an excellent effect that the structure is simple and high reliability can be obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a variable valve mechanism that embodies the present invention.
FIG. 2 is a cross-sectional view showing the operation of the mechanism when a maximum lift amount and operating angle are required.
FIG. 3 is a cross-sectional view showing the operation following FIG. 2;
FIG. 4 is a cross-sectional view showing the operation of the mechanism when a minute lift amount and operating angle are required.
FIG. 5 is a cross-sectional view showing the operation of the mechanism when lift suspension is necessary.
FIG. 6 is a graph showing a lift amount and a working angle of a valve obtained by the same mechanism.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rocker arm 2 Concave spherical surface part 3 Pivot 5 Roller 7 First rotation cam 7a Base circle 7b Nose gradually increasing part 7c Nose 7d Nose gradually decreasing part 8 Second rotating cam 8a Base circle 8b Nose gradually increasing part 8c Nose 8d Nose gradually decreasing part 9 Valve 10 Mechanical Adjuster 11 Inner first member 12 Outer second member 13 Lost motion spring

Claims (3)

While pressed by the first rotating cam the cam corresponding portion of the rocker arm, so as to press the second rotary cam for rotating the swing center of the rocker arm at the same rotational speed as the first rotating cam via the A Justa, wherein A phase change device for changing the lift amount and the operating angle of the valve by changing the phase of the second rotary cam with respect to the first rotary cam continuously or stepwise according to the operating condition of the internal combustion engine ;
The adjuster is a variable valve mechanism that includes a first member and a second member that are engaged with each other so as to contact and be separated from each other, and a lost motion spring that urges the first member and the second member in the separating direction .   The variable valve mechanism according to claim 1, wherein the swing center portion is a concave spherical surface portion supported by a pivot, and an adjuster is connected to the pivot. The variable valve mechanism according to claim 1, wherein a tappet clearance adjusting mechanism using a screw is provided between the swing center portion and the adjuster.

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