JPH1018823A - Variable valve gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable valve gear which can be continuously variably controlled through displacement of a cam shaft and adapted to an internal combustion engine with a multi-valve structure by arranging solid cams and arms by number half as valve number, and forming the solid cam with large width on the cam shaft. SOLUTION: A variable valve gear has a cam shaft 1 provided with a solid cam 2 whose profile is continuously varied in an axial direction, a displacement device 3 which continuously displaces the cam shaft 1 in an axial direction according to an operation condition, a swing arm 6 or a rocker arm which simultaneously opens and closes two adjacent valves 5 through oscillation based on the profile of the solid cam 2. The swing arm 6 is provided with a roller mechanism 11 having a follow-up contact part being in contact with the solid cam 2 while following up variation of the contact linear angle accompanied with the rotation of the solid cam 2, and a pin 8 with a male screw for pressurizing ends of the two valves 5. A cam for idling rotation whose profile is not varied may be arranged on the cam shaft 1, other than the solid cam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve mechanism which changes a valve timing and a lift continuously or stepwise from a low rotation to a high rotation of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, various valve operating mechanisms have been known in which a valve timing (including a valve opening operating angle and a phase) and a lift amount are changed in two stages between a low rotation and a high rotation of an internal combustion engine. ing. According to these variable valve mechanisms, various characteristics such as torque, output, fuel consumption, and cleanliness of exhaust gas are considerably improved as compared with a general valve mechanism. In FIG. 7, the torque characteristics of the internal combustion engine obtained by these conventional variable valve operating mechanisms are indicated by dashed-dotted lines, and the torque characteristics of the internal combustion engine obtained by a general valve operating mechanism having no change are indicated by broken lines. The former has an increase in torque over the entire rotation range with respect to the latter. In addition, depending on the setting, the fuel efficiency can be up to 8 to 1
It is said to improve by about 0%.

[0003]

However, since these conventional variable valve mechanisms have only two stages of change, it is difficult to perform precise control in accordance with the operating conditions of the internal combustion engine, and as shown in FIG. A valley occurs in the torque characteristics, it is difficult to achieve both low-torque torque and high-speed output, or two or three arms are required for one valve, which complicates the structure. , It is difficult to make compact,
As the switching mechanism, a type in which the pin is moved with high hydraulic pressure is mainly used, there is a problem that there is a failure in switching at a single time, abnormal noise or wear.

Accordingly, the present inventor has firstly provided a camshaft provided with a three-dimensional cam having a continuously changed cam profile, a displacement device for continuously or stepwise displacing the camshaft in the axial direction, A variable valve mechanism having an arm that opens and closes a valve by swinging based on the cam profile of the three-dimensional cam has been invented (Japanese Patent Application No. 7-1924).
No. 32, unpublished at the time of filing the present application). According to the present invention, the above-mentioned problems can be solved, but the following problems remain.

[0005] Recent internal combustion engines have three valves per cylinder,
With the increase in the number of valves such as four valves or five valves (multi-valve), a large number of cams are densely formed on a camshaft. However, in order to displace the three-dimensional cam in the axial direction, the length of the three-dimensional cam in the axial direction (hereinafter, referred to as a cam width) is desired to be larger than that of a general cam. It was difficult to do. For this reason, it is difficult to make a multi-valve with the above-described variable valve mechanism, and if this is done, the cam width of the three-dimensional cam must be reduced to about the same as that of a general cam. Then, the change rate of the cam profile in the axial direction of the three-dimensional cam becomes steep, and the amount of displacement of the camshaft becomes small, so that there has been a problem that it is difficult to perform continuous variable control based on the displacement.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to continuously or stepwise change a valve timing and a lift amount to obtain various characteristics such as torque, output, fuel consumption, and cleanness of exhaust gas. Can be maximized over the entire rotation range of the internal combustion engine, and not only can the change be made smoothly and quietly, but also the number of three-dimensional cams and arms can be reduced to less than half the number of valves. And a three-dimensional cam having a large cam width can be formed on the camshaft. Accordingly, the rate of change in the axial direction of the cam profile of the three-dimensional cam is moderated, the displacement of the camshaft is increased, and continuous variable control based on the displacement is easy, and the present invention is applicable to a multi-valve internal combustion engine. A variable valve mechanism is provided.

In order to achieve the above object, a variable valve mechanism according to the present invention provides a cam having a three-dimensional cam in which a cam profile is continuously changed in an axial direction from a low-rotation cam profile to a high-rotation cam profile. A shaft, a displacement device for continuously or stepwise displacing the camshaft in the axial direction according to an operation state such as a rotation speed of the internal combustion engine, and a displacement device adjacent to the shaft by swinging based on a cam profile of the three-dimensional cam. An arm for simultaneously opening and closing the above (preferably two or three) valves, wherein the arm includes a follow-up contact portion that contacts the three-dimensional cam while following a change in a contact line angle accompanying rotation of the three-dimensional cam. And two or more (preferably two or three) pressing parts for pressing the ends of two or more valves.

Here, the phase, valve opening angle and lift amount of the valve timing in the cam profile for low rotation and the phase, valve opening angle and lift amount of the valve timing in the cam profile for high rotation are determined for each internal combustion engine. Can be set as appropriate according to the requirements in.
However, in many cases, the cam profile for low rotation has a small valve opening angle and lift amount, and the cam profile for high rotation has a large valve opening angle and lift amount.

When the camshaft is displaced in a stepwise manner by the displacement device, the camshaft may be changed in two steps. In that case, it is preferable that the displacement in the two steps can be adjusted. More preferably, the camshaft is displaced in at least three stages. Most preferably, the camshaft is continuously displaced. The displacement device is not limited to a specific structure, but may be a device using hydraulic pressure, electromagnetic force, or the like.

The following can be exemplified as the arm. 1) One end is pivotally supported on the rocker shaft,
A swing arm having a valve pressing portion at the other end and a roller mechanism with a follow-up contact portion at the center. 2) A swing arm having one end pivotally supported by a pivot, a valve pressing portion at the other end, and a roller mechanism with a follow-up contact portion at the center. 3) A rocker arm having a roller mechanism with a follow-up contact portion at one end, a valve pressing portion at the other end, and an intermediate portion pivotally supported by a rocker shaft.

The following mechanism (A) is used as the following contact mechanism.
(B) can be illustrated. (A) A mechanism comprising a semi-cylindrical inner seat provided on an arm and a follow-up contact portion fitted to the semi-cylindrical inner seat so as to be able to roll. (B) A roller mechanism with a follow-up contact portion. The following (B1) to (B4) can be exemplified as the roller mechanism with the following contact portion.

(B1) a spindle attached to the arm;
A spherical slide bearing externally slidably and rotatably mounted on a support shaft, wherein the outer race of the spherical slide bearing is a follow-up contact portion. (B2) A support shaft attached to an arm and a self-aligning rolling bearing externally slidably and rotatably mounted on the support shaft, wherein the outer race of the self-aligning rolling bearing is used as a follow-up contact portion. . (B3) Roller bearing whose outer peripheral surface is a convex spherical surface and which is attached to an arm, and whose inner peripheral surface of the inner race is a concave spherical surface and which is externally slidably and rotatably and tiltably mounted on the ball support shaft. With the outer race of the rolling bearing as the following contact part. (B4) A support shaft attached to the arm, and a roller whose outer peripheral surface is a convex spherical surface and is externally slidably and rotatably mounted on the support shaft, and particularly the convex spherical surface of the roller is a follow-up contact portion. Things.

An idle rotation cam whose cam profile does not change in the axial direction is provided adjacent to the low-rotation cam profile side of the three-dimensional cam. Load rotating contact surface
It is preferable that an idle rotation contact surface that comes into contact with the idle rotation cam during idle rotation of the internal combustion engine is provided side by side. Further, it is preferable that a gap is provided between the three-dimensional cam and the idle rotation cam to allow a boundary portion between the load rotation contact surface and the idle rotation contact surface of the following contact portion to escape.

The variable valve mechanism of the present invention can be applied to either an intake valve or an exhaust valve, but is preferably applied to both.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a variable valve mechanism in which the present invention is applied to both an intake valve and an exhaust valve will be described below with reference to the drawings. Therefore, in the embodiment, simply referring to a valve refers to both an intake valve and an exhaust valve.

First, FIGS. 1 to 7 show a variable valve mechanism according to a first embodiment. A camshaft 1 has a cam from a low-speed cam profile on the right to a high-speed cam profile on the left in FIG. A three-dimensional cam 2 whose profile is continuously changed in the axial direction is formed. The three-dimensional cam 2 includes a base circular portion 2a and a nose portion 2b. The base circular portion 2a has the same radius in both the low-rotation cam profile and the high-rotation cam profile, and thus has a cylindrical surface without inclination. However, since the nose portion 2b has a small valve opening action angle and a lift amount in the low rotation cam profile and has a large valve opening action angle and the lift amount in the high rotation cam profile, the nose portion 2b is inclined like a conical surface. I have.

At the end of the camshaft 1, there is provided a displacement device 3 for continuously displacing the camshaft 1 in the axial direction according to the operating condition such as the rotation speed of the internal combustion engine. The displacement device 3 includes a guide portion of the camshaft 1 using splines and a driving portion of the camshaft 1 using hydraulic pressure (both are not shown), and is based on a rotation sensor, an accelerator opening sensor, etc. of the internal combustion engine. The operation is controlled by a control device (not shown) such as a microcomputer which operates in a controlled manner.

A rocker shaft 4 disposed obliquely below the camshaft 1 is rotatable with a swing arm 6 that simultaneously opens and closes two adjacent valves 5 by swinging based on the cam profile of the three-dimensional cam 2. It is attached to the shaft. The swing arm 6 has a rocker shaft 4 at the right end.
The two branch portions 6a which are bifurcated at the left end are provided with a male threaded pin 8 as a valve pressing portion and a fixing nut 9 thereof. The accommodation hole 10 formed in the center in the vertical direction is provided with a roller mechanism 11 having a follow-up contact portion that contacts the three-dimensional cam 2 while following a change in the contact line angle accompanying the rotation of the three-dimensional cam 2. I have.

The roller mechanism 11 with a follow-up contact portion is
A hollow support shaft 12 is fixed to the swing arm 6 by swaging, and a spherical slide bearing 13 is slidably and externally inserted into the hollow support shaft 12. The spherical plain bearing 13 has an inner race 1 whose outer peripheral surface is a convex spherical surface.
4 and an outer race 15 externally slidably and pivotably and tiltably inserted into the inner race 14 with an inner peripheral surface being a concave spherical surface. The outer race 15 is a follow-up contact portion for the three-dimensional cam 2. I have. The outer race 15 is formed narrower than the inner race 14, and stopper rings 16 for preventing the outer race 15 from coming off are fitted in grooves at both ends of the inner race 14.

The variable valve mechanism according to this embodiment operates as follows. First, when the internal combustion engine is running at low speed, as shown in FIG. 4, the camshaft 1 is displaced to the left by the displacement device 3, and the right low-speed cam profile of the three-dimensional cam 2 has a roller mechanism with a follow-up contact portion. Corresponds to 11. Then, as shown in FIG. 4A, when the base circle portion 2a comes into contact with the outer race 15, the contact line angle is parallel to the axis of the three-dimensional cam 2, so that the outer race 15 is
4 does not incline with respect to 4, but contacts the base circle portion 2a. Further, as shown in FIG. 4B, when the nose portion 2b contacts the outer race 15, the contact line angle is inclined by a predetermined angle with respect to the axis of the three-dimensional cam 2, so that the outer race 15 is
4 and makes a good contact with the nose portion 2b.

As described above, the outer race 15 tilts once for each rotation of the three-dimensional cam 2, contacts the three-dimensional cam 2 while following the change in the contact line angle, and is pressed by the nose portion 2b.
Accordingly, the swing arm 6 swings based on the cam profile for low rotation, and as shown by a curve L in FIG. 6, the two valves 5 on the exhaust side and the intake side are opened with a small valve opening operation angle and lift amount. Open and close to increase low-speed torque,
Improve fuel economy.

When the internal combustion engine is rotating at high speed, the camshaft 1 is displaced rightward by the displacement device 3 as shown in FIG. Corresponds to the attached roller mechanism 11. And, as shown in FIGS. 5A and 5B, the outer race 15
It tilts once for each rotation of the three-dimensional cam 2, contacts the three-dimensional cam 2 while following the change in the contact line angle, and is pressed by the nose portion 2b. Accordingly, the swing arm 6 swings based on the cam profile for high rotation, and as shown by the curve H in FIG. 6, the two valves 5 on the exhaust side and the intake side are opened at a large valve opening operation angle and a large lift amount. Open and close, increase the intake volume,
Increase high-speed output.

In the course of the rotation from low rotation to high rotation, the camshaft 1 is continuously displaced by the displacement device 3 in accordance with the operating conditions such as the number of revolutions and the accelerator opening, and the three-dimensional cam 2 Among them, the cam profile of the intermediate portion corresponds to the roller mechanism 11 with the follow-up contact portion. Therefore,
The swing arm 6 swings based on the cam profile, and opens and closes the two valves 5 on the exhaust side and the intake side at an intermediate valve opening duration and lift amount as shown by a curve M in FIG. , And generates a torque and an output according to the driving situation.

As described above, according to the variable valve mechanism of the present embodiment, the valve timing and the lift amount are continuously changed from the time of low rotation to the time of high rotation of the internal combustion engine, and the operating condition of the internal combustion engine is changed. , And various characteristics such as torque, output, fuel efficiency, and cleanliness of exhaust gas can be maximized over the entire rotation range. FIG. 7 shows the torque characteristic of the internal combustion engine obtained by the present embodiment by a solid line, but the torque increases over the entire rotation range with respect to the conventional variable valve mechanism shown by the dashed line. There are no valleys. Further, depending on the setting, it is considered that the fuel efficiency can be improved by about 15 to 20% at the maximum.

In addition, the change can be performed smoothly and quietly by the displacement of the camshaft 1.

Further, the three-dimensional cam 2 and the swing arm 6
Is only half of the number of valves 5, so that the three-dimensional cam 2 having a large cam width can be formed on the camshaft 1.
Therefore, the rate of change of the cam profile in the three-dimensional cam 2 in the axial direction can be moderated, and the displacement of the camshaft can be increased. Therefore, the variable valve mechanism can easily perform continuous variable control by the displacement of the camshaft 1 and can be applied to an internal combustion engine having a multi-valve structure.

FIGS. 8 and 9 show a variable valve mechanism according to the second embodiment. Only the point where the right end of the swing arm 6 is swingably supported by a pivot 19 with a hydraulic adjuster 18 will be described. This is different from the first embodiment.

FIGS. 10 and 11 show a variable valve mechanism according to the third embodiment, which differs from the first embodiment only in that a rocker arm 20 is used instead of a swing arm. The rocker arm 20 has a roller mechanism 11 with a follow-up contact portion at the right end, a male threaded pin 8 as a valve pressing portion and its fixing nut 9 at two branch portions 6a at the left end, and a rocker shaft at an intermediate portion. 4 are provided. The camshaft 1 and its three-dimensional cam 2 are located below the roller mechanism 11 with a follow-up contact portion. The rocker arm 20 swings like a seesaw unlike the swing arm, but otherwise exerts the same operation as the first embodiment.

Next, FIG. 12, FIG. 13, FIG.
Reference numeral 5 denotes a variable valve mechanism according to the fourth, fifth, sixth, and seventh embodiments, respectively, which differs from the first embodiment only in the specific configuration of the roller mechanism 11 with a follow-up contact portion.

In the roller mechanism 11 with a follow-up contact portion according to the fourth embodiment shown in FIG. 12, the outer race 15 is divided into two parts so that the outer race 15 can be easily inserted into the inner race 14 and the outer races 15 are not separated. The cover ring 21 is attached to the outer periphery by caulking.

The roller mechanism 11 with a follow-up contact portion according to the fifth embodiment shown in FIG. 13 comprises a hollow support shaft 12 and a self-aligning roller bearing 22 which is slidably and rotatably mounted on the hollow support shaft 12. The self-aligning rolling bearing 22 includes an inner race 23, a roller 24 (or a ball), and an outer race 25 having a concave spherical inner surface, and the outer race 25 serves as a follow-up contact portion. .

The roller mechanism 11 with a follow-up contact portion according to the sixth embodiment shown in FIG. 14 has a convex spherical outer peripheral surface, and has a ball support shaft 26 attached to the swing arm 6 and a sliding motion about the ball support shaft 26. A rolling bearing 27 is externally movably and tiltably inserted. The rolling bearing 27 includes an inner race 28 having a concave spherical inner surface, a roller 29 (or a ball), and an outer race 30. The race 30 is the following contact portion.

A roller mechanism 11 with a follow-up contact portion according to a seventh embodiment shown in FIG. 15 has a hollow support shaft 12 and an outer peripheral surface formed as a convex spherical surface. The convex spherical surface 32 of the roller 31 is a follow-up contact portion. When the base circular portion 2a contacts the convex spherical surface 32, the contact line angle is parallel to the axis of the three-dimensional cam 2, so that the top of the convex spherical surface 32 is
a. When the nose portion 2b comes into contact with the convex spherical surface 32, the contact line angle is inclined with respect to the axis of the three-dimensional cam 2, so that a portion slightly lower than the top of the convex spherical surface 32 makes good contact with the nose portion 2b.

FIGS. 16 to 18 show a variable valve mechanism according to an eighth embodiment, which differs from the first embodiment only in that a structure for stabilizing the idle rotation of the internal combustion engine is added. It is. That is, in the first embodiment, at the time of the idle rotation without the load of the internal combustion engine, the rotation speed becomes the minimum rotation speed (generally, about 650 rpm in an automobile), and the state of the curve L in FIG. The lap angle should be X0. However, due to the processing accuracy of the three-dimensional cam 2 (it tends to be lower than the processing accuracy of a general cam) and the control accuracy of the axial position of the camshaft 1, the overlap angle varies and increases to, for example, X1 in FIG. May be. Then, there is a problem that the idle rotation becomes unstable and disturbed.

Therefore, in the present embodiment, an idle rotation cam 35 whose cam profile does not change in the axial direction is juxtaposed next to the low rotation cam profile side of the three-dimensional cam 2. The cam profile of the idle rotation cam 35 (curve I in FIG. 18A) is the same as the endmost low rotation cam profile of the three-dimensional cam 2 (curve L in FIG. 18B).

On the outer peripheral surface of the outer race 15, a load rotation contact surface 36 that comes into contact with the three-dimensional cam 2 during a load rotation (including a low rotation to a high rotation) with a load of the internal combustion engine.
(The left half of the outer race 15 in FIG. 16) and the idling cam 35 during idling without the load of the internal combustion engine.
The contact surface 37 for idling rotation (the right half of the outer race 15 in FIG. 16) is arranged side by side in a mountain shape. A gap 39 is provided between the three-dimensional cam 2 and the idle rotation cam 35 to allow a boundary 38 between the load rotation contact surface 36 and the idle rotation contact surface 37 to escape.

The variable valve mechanism according to this embodiment operates as follows. First, when the internal combustion engine is idling,
As shown in FIG. 16, the camshaft 1 is completely displaced leftward, and the idle rotation cam 35 corresponds to the idle rotation contact surface 37 of the outer race 15.

As shown in FIG. 16A, when the base circular portion 35a of the idle rotation cam 35 contacts the idle rotation contact surface 37, the contact line angle is horizontal, and the load rotation contact is made. The surface 36 is separated from the base circular portion 2a of the three-dimensional cam 2. Also, as shown in FIG. 16 (b), when the nose portion 35b of the idle rotation cam 35 contacts the idle rotation contact surface 37, the contact line angle is horizontal, and the load rotation contact surface 36 Formally contacts the nose 2b of the three-dimensional cam 2.

Accordingly, the swing arm 6 swings based on the cam profile of the idle rotation cam 35, and
As shown by the curve I in FIG. 8A, the two valves 5 on the exhaust side and the intake side are opened and closed with a small valve opening operation angle and a small lift amount. The cam profile of the idle rotation cam 35 does not change in the axial direction, and is not affected by the control accuracy of the axial position of the camshaft 1. Further, the idle rotation cam 35 can be expected to have high machining accuracy. For this reason, the overlap angle between the exhaust valve and the intake valve is determined to be X0, and the idle rotation is stabilized.

At the time of load rotation of the internal combustion engine, FIG.
As shown in (1), the camshaft 1 is displaced rightward, the idle rotation cam 35 is disengaged from the idle rotation contact surface 37 of the outer race 15, and the low rotation cam profile or the high rotation cam profile of the three-dimensional cam 2 is changed to the outer race. This corresponds to 15 load rotation contact surfaces 36. The outer race 15 tilts at a small angle with the switching of the contact surfaces 37 and 36, but the gap 39
Escapes the boundary corner 38, so that the switching is smooth.

The outer race 15 is shown in FIG.
As shown in (b), the three-dimensional cam 2 tilts once for each rotation, contacts the three-dimensional cam 2 while following the change in the contact line angle, and is pressed by the nose portion 2b. Therefore, the swing arm 6 swings based on the low-rotation cam profile or the high-rotation cam profile as in FIGS. 4 and 5 of the first embodiment, and the curves L to M to H in FIG. As shown in (2), the two valves 5 on the exhaust side and the intake side are opened and closed at an optimum valve opening duration and lift amount.

19 to 23 show a variable valve mechanism according to a ninth embodiment, in which a following contact mechanism 40 having the following structure is used in place of the roller mechanism 11 with a following contact section. Only in the point, it is different from the first embodiment.

On the upper surface of the central portion of the swing arm 6, a protruding portion 41 which is long in a direction perpendicular to the axis of the three-dimensional cam 2 is formed.
A semi-cylindrical inner surface seat 42 extending in the same direction is recessed in the raised portion 41, and both ends of the seat 42 are closed by closed walls 43. The semi-cylindrical inner seat 42 includes a semi-cylindrical surface 45 that comes into contact with the semi-cylindrical inner seat 42 in a slidable manner and a flat contact surface 46 that contacts the three-dimensional cam 2. Part 4
4 is fitted so as to be able to roll. Follow contact 44
Is configured to contact the three-dimensional cam 2 on the contact surface 46 while following a change in the contact line angle accompanying the rotation of the three-dimensional cam 2 by a small-angle roll motion.

The variable valve mechanism according to the present embodiment operates as follows. First, when the internal combustion engine is running at a low speed, as shown in FIG. 22, the camshaft 1 is displaced leftward by the displacement device 3, and the right low-speed cam profile of the three-dimensional cam 2 corresponds to the following contact portion 44. I do. And FIG.
As shown in (a), the base circle portion 2a is
When the contact is made with the contact surface 46, the contact line angle is parallel to the axis of the three-dimensional cam 2, so that the contact surface 46 does not incline with respect to the upper surface of the swing arm 6 and contacts the base circular portion 2a. Further, as shown in FIG. 22B, when the nose portion 2b comes into contact with the contact surface 46 of the follow contact portion 44, the contact line angle is inclined by a predetermined angle with respect to the axis of the three-dimensional cam 2, so that the follow contact portion 44 Rolls by the same angle, and the contact surface 46 makes good contact with the nose portion 2b.

As described above, the follow-up contact portion 44 is
The roller makes a small-angle roll motion for each rotation of, and contacts the three-dimensional cam 2 while following the change in the contact line angle, and is pressed by the nose portion 2b. Therefore, the swing arm 6 swings based on the cam profile for low rotation, and as in the first embodiment,
The two valves 5 on the exhaust side and the intake side are opened and closed with a small valve opening angle and a small lift to increase low-speed torque and improve fuel economy.

When the internal combustion engine is rotating at a high speed, the camshaft 1 is displaced rightward by the displacement device 3 as shown in FIG. 44 corresponding. Then, as shown in FIGS. 23 (a) and 23 (b), the follow-up contact portion 44 makes a roll motion once for each rotation of the three-dimensional cam 2, and contacts the three-dimensional cam 2 while following the change of the contact line angle. Then, it is pressed by the nose portion 2b. Therefore, the swing arm 6 swings based on the cam profile for high rotation, and opens and closes the two valves 5 on the exhaust side and the intake side with a large valve opening operation angle and a lift amount similarly to the first embodiment. , Increase the intake volume, increase the high-speed output.

The camshaft 1 is continuously displaced by the displacement device 3 in accordance with the operating conditions such as the number of revolutions and the degree of opening of the accelerator, even during the period from the low rotation to the high rotation. Among them, the cam profile of the intermediate portion corresponds to the following contact portion 44. Therefore, the swing arm 6 swings based on the cam profile, and opens and closes the two valves 5 on the exhaust side and the intake side at an intermediate valve opening operation angle and a lift amount similarly to the first embodiment. , And generates a torque and an output according to the driving situation.

Next, FIGS. 24 and 25 show a variable valve mechanism of the tenth embodiment, in which the idle rotation stabilizing structure of the eighth embodiment is combined with the follow-up contact mechanism 40 of the ninth embodiment. . That is, as in the eighth embodiment, the idle rotation cam 35 is provided adjacent to the three-dimensional cam 2 on the side of the low rotation cam profile, and the contact surface 47 for load rotation and the idle surface The rotation contact surface 48 is arranged in a mountain shape.

Accordingly, the variable valve mechanism according to the present embodiment operates as follows. First, when the internal combustion engine is idling, as shown in FIGS. 24A and 24B, the idle rotation cam 35 comes into contact with the idle rotation contact surface 48. It swings based on the profile, and similarly to the eighth embodiment, the two valves 5 on the exhaust side and the intake side are opened and closed with a small valve opening operation angle and a small lift amount to stabilize the idle rotation.

Next, at the time of load rotation of the internal combustion engine, FIG.
As shown in (a) and (b), since the three-dimensional cam 2 comes into contact with the load rotation contact surface 47, the swing arm 6 swings based on the optimum cam profile, and the exhaust is performed similarly to the eighth embodiment. The two valves 5 on the side and the intake side are opened and closed at the optimum valve opening duration and lift amount.

The same effects as those of the first embodiment can be obtained by the variable valve mechanisms of the second to tenth embodiments.
In addition, the roller mechanism 11 with a follow-up contact portion of the fourth, fifth, sixth, seventh or eighth embodiment, or the follow-up contact mechanism 40 of the ninth or tenth embodiment is changed to the second or third embodiment. It can also be applied.

It should be noted that the present invention is not limited to the configuration of the above-described embodiment, and may be embodied with the following modifications without departing from the spirit of the invention. (1) The camshaft 1 is displaced stepwise. (2) The configuration and control method of the displacement device 3 are appropriately changed.

[0053]

Since the variable valve mechanism of the present invention is constructed as described above, the valve timing and the lift amount are continuously or stepwise changed to change the torque, output, fuel consumption and exhaust gas. Various characteristics such as cleanliness can be maximized over the entire rotation range of the internal combustion engine,
In addition, not only the change can be made smoothly and quietly, but also the number of the three-dimensional cams and arms can be less than half of the number of valves, so that a three-dimensional cam having a large cam width can be formed on the camshaft. It works. Accordingly, the rate of change of the cam profile in the axial direction of the three-dimensional cam can be moderated, and the displacement of the camshaft can be increased, so that continuous variable control based on the displacement is easy, and the present invention can be applied to an internal combustion engine having a multi-valve structure. A variable valve mechanism can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a variable valve mechanism according to a first embodiment of the invention.

FIG. 2 is a front view of the variable valve mechanism.

FIG. 3 is a plan view of the variable valve mechanism.

FIG. 4 is a sectional view taken along line IV-IV of FIG. 2 when the internal combustion engine is running at a low speed.
It is a line sectional view.

FIG. 5 is a sectional view taken along line IV-IV of FIG. 2 when the internal combustion engine is rotating at a high speed.
It is a line sectional view.

FIG. 6 is a graph showing valve timing and lift amount by the variable valve mechanism.

FIG. 7 is a graph showing torque characteristics of an internal combustion engine obtained by the variable valve mechanism in comparison with a conventional example.

FIG. 8 is a front view showing a variable valve mechanism according to a second embodiment.

FIG. 9 is a plan view of FIG.

FIG. 10 is a front view showing a variable valve mechanism according to a third embodiment.

FIG. 11 is a plan view of FIG. 10;

FIG. 12 is a sectional view of a main part of a fourth embodiment.

FIG. 13 is a sectional view of a main part of a fifth embodiment.

FIG. 14 is a sectional view of a main part of a sixth embodiment.

FIG. 15 is a perspective view showing a variable valve mechanism according to a seventh embodiment.

FIG. 16 is a cross-sectional view illustrating the variable valve mechanism according to the eighth embodiment when the internal combustion engine is idling.

FIG. 17 is a cross-sectional view showing the variable valve mechanism at the time of load rotation of the internal combustion engine.

FIG. 18 is a graph showing valve timing and lift by the variable valve mechanism.

FIG. 19 is a perspective view showing a variable valve mechanism according to a ninth embodiment.

FIG. 20 is a front view of the variable valve mechanism.

FIG. 21 is a plan view of the variable valve mechanism.

22. XXI of FIG. 20 at the time of low rotation of the internal combustion engine
It is an I-XXII line sectional view.

FIG. 23 shows XXI of FIG. 20 when the internal combustion engine is rotating at a high speed
It is an I-XXII line sectional view.

FIG. 24 is a sectional view showing the variable valve mechanism according to the tenth embodiment when the internal combustion engine is idling.

FIG. 25 is a cross-sectional view showing the variable valve mechanism when the internal combustion engine is rotating under load.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Camshaft 2 Solid cam 3 Displacement device 4 Rocker shaft 5 Valve 6 Swing arm 6a Branch part 8 Pin with male screw 9 Fixed nut 11 Roller mechanism with follow-up contact part 15 Outer race 20 Rocker arm 21 Covering 25 Outer race 30 Outer race 32 Convex Spherical sphere 35 Idle rotation cam 36 Load rotation contact surface 37 Idle rotation contact surface 38 Boundary corner 39 Gap 40 Follow-up contact mechanism 42 Semi-cylindrical inner seat 44 Follow-up contact 45 Semi-cylindrical surface 46 Contact surface 47 Load rotation Contact surface 48 Contact surface for idle rotation

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location F01L 1/26 F01L 1/26 B

Claims (5)

[Claims] 1. A camshaft having a three-dimensional cam in which a cam profile is continuously changed in an axial direction from a low-rotation cam profile to a high-rotation cam profile, and according to an operating condition such as a rotation speed of an internal combustion engine. A displacement device for continuously or stepwise displacing the camshaft in the axial direction, and an arm for simultaneously opening and closing two or more adjacent valves by swinging based on a cam profile of the three-dimensional cam, The arm has a follow-up contact mechanism including a follow-up contact portion that contacts the three-dimensional cam while following a change in the contact line angle accompanying the rotation of the three-dimensional cam, and two or more presses that press the ends of the two or more valves. And a variable valve operating mechanism. 2. The variable movement mechanism according to claim 1, wherein said follow-up contact mechanism comprises a semi-cylindrical inner seat provided on said arm, and a follow-up contact portion fitted to said semi-cylindrical inner face so as to be able to roll. Valve mechanism. 3. The variable valve mechanism according to claim 1, wherein said follow-up contact mechanism is a roller mechanism with a follow-up contact portion. 4. An idle rotation cam whose cam profile does not change in the axial direction is juxtaposed next to the low rotation cam profile side of the three-dimensional cam.
3. The load rotation contact surface that contacts the three-dimensional cam when the internal combustion engine rotates at a load, and the idle rotation contact surface that contacts the idle rotation cam when the internal combustion engine idles. 3. The variable valve mechanism according to 3. 5. A gap is provided between the three-dimensional cam and the idle rotation cam to allow a boundary between the load rotation contact surface and the idle rotation contact surface of the following contact portion to escape. Item 5. The variable valve mechanism according to Item 4.