JP3415706B2 - Variable valve 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 variable valve mechanism that changes the valve timing and the lift amount continuously or stepwise from low speed to high speed of an internal combustion engine.

[0002]

2. Description of the Related Art Heretofore, various valve operating mechanisms have been known which change a valve timing (including a valve opening operating angle and a phase) and a lift amount in two stages depending on whether an internal combustion engine is operating at low speed or high speed. ing. For example, there is a variable valve mechanism of a type in which a low rotation cam having a small valve opening operating angle and lift amount and a high rotation cam having a large valve opening operating angle and lift amount are switched to swing a swing arm. . In this type, at low rotation speed, as shown by the solid line in FIG. 18, both the left exhaust valve and the right intake valve have a smaller valve opening angle and lift amount to give a swirl to the intake air and increase the low speed torque. , Improve fuel economy. Further, at the time of high rotation, as shown by the broken line in FIG. 18, both the exhaust valve and the intake valve increase the valve opening working angle and the lift amount to increase the intake amount and increase the high speed output.

Further, by rotating the intake-side camshaft at a constant angle by a displacement device using a helical spline during low speed rotation and high rotation speed of the internal combustion engine, the valve opening operating angle and the lift amount remain unchanged. There is a variable valve mechanism that changes only the timing phase and presses the direct hit type valve lifter with the intake cam. In this type,
When the engine speed is low, as shown by the solid line in FIG. 19, the phase of the valve timing of the intake valve on the right side is shifted to the exhaust valve side on the left side to increase the valve overlap to obtain the effect of early intake closing and increase the low speed torque. While improving fuel efficiency. Further, at the time of high rotation, as shown by the broken line in FIG.
The phase of the valve timing of the intake valve is shifted in the direction away from the left exhaust valve, the valve overlap is reduced, the intake time is lengthened, and high-speed output is increased.

According to these conventional variable valve operating mechanisms, various characteristics such as torque, output, fuel consumption, and cleanliness of exhaust gas are considerably improved as compared with a general valve operating mechanism. In Figure 7,
The torque characteristics of the internal combustion engine obtained by these conventional variable valve actuation mechanisms are shown by the one-dot chain line, and the torque characteristics of the internal combustion engine obtained by the general valve actuation mechanism that has no variability are shown by the broken line. On the other hand, the torque is increasing over the entire rotation range. Also, depending on the setting, the maximum fuel consumption is 8 ~.
It is said to improve by about 10%.

[0005]

However, these conventional variable valve actuation mechanisms still have the following problems. In any of the above types, only the valve timing or the lift amount is changed in two steps at low rotation speed and high rotation speed, so it is difficult to perform precise control according to the operating condition of the internal combustion engine. Then, as shown by the alternate long and short dash line in FIG. 7, a valley may occur in the torque characteristic at the switching point between low speed rotation and high speed rotation. This phenomenon was likely to appear particularly when setting was made with emphasis on the high rotation range (for example, 8000 rpm or more).

When changing only the valve timing phase while keeping the valve opening angle and the lift amount as they are, if the valve opening angle is increased by emphasizing the output at high rotation, the valve opening angle at low rotation can be increased. Torque is sacrificed, idling becomes unstable, and if the valve opening operating angle is made small with emphasis on torque at low speed, output at high speed will be sacrificed.
There was a trade-off problem.

When switching between a low rotation cam having a small valve opening working angle and lift amount and a high rotation cam having a large valve opening working angle and lift amount, the above-mentioned trade-off problem can be solved, but one valve Against two cams and two ~
Since three arms are required, the structure becomes complicated,
There was a problem that it was difficult to make it compact. In addition, as the switching mechanism, the type that moves the pin with high hydraulic pressure was the mainstream, so it does not switch smoothly with one operation, abnormal noise is generated at the time of switching, or part of it wears out. There was a problem of lack of reliability. Further, there is also a problem that a high hydraulic power source is required to speed up the switching response.

Therefore, an object of the present invention is to solve the above problems and to operate the internal combustion engine by changing the valve timing and the lift amount continuously or stepwise from the low speed to the high speed of the internal combustion engine. Precise control according to the situation can be performed, and various characteristics such as torque, output, fuel efficiency, and cleanliness of exhaust gas can be maximized over the entire rotation range, and the changes can be made smoothly and quietly. Further, the present invention provides a new variable valve mechanism that can be performed in one unit and one solid cam and one arm for one valve, simplifying the structure and achieving compactness. Especially.

[0009]

In order to achieve the above object, the variable valve mechanism of the present invention continuously changes the cam profile in the axial direction from the low rotation cam profile to the high rotation cam profile. A camshaft equipped with a three-dimensional cam, a displacement device that displaces the camshaft continuously or stepwise in the axial direction according to the operating conditions such as the rotation speed of the internal combustion engine, and swings based on the cam profile of the three-dimensional cam. It is characterized by including an arm for opening and closing the valve by doing so, and the arm is provided with a roller mechanism with a follow-up contact portion which comes into contact with the three-dimensional cam while following the change in the contact line angle accompanying the rotation of the three-dimensional cam.

Here, the phase of valve timing, valve operating angle and lift amount in the cam profile for low rotation and the phase of valve timing, valve operating angle and lift amount in cam profile for high rotation are the individual internal combustion engine. It can be appropriately set according to the requirements in the above.
However, in many cases, the low rotation cam profile has a small valve opening working angle and lift amount, and the high rotation cam profile has a large valve opening working angle and lift amount.

When the camshaft is displaced stepwise by the displacement device, it may be changed in two steps, but in that case, it is preferable to be able to adjust the displacement in two steps. More preferably, the camshaft is displaced in at least three steps. Most preferably, the camshaft is continuously displaced. The displacement device is not limited to a specific structure, and may be one 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 that has a valve pressing part at the other end and a roller mechanism with a follow-up contact part at the center. 2) A swing arm having one end swingably supported by a pivot, a valve pressing part at the other end, and a roller mechanism with a follow-up contact part at the center. 3) A rocker arm having a roller mechanism with a follow-up contact part at one end, a valve pressing part at the other end, and an intermediate part pivotally supported by a rocker shaft.

As the roller mechanism with the follow-up contact portion, the following can be exemplified. B) A support shaft that is attached to the arm and a spherical slide bearing that is slidably mounted on the support shaft so that the outer race of the spherical slide bearing serves as the follow-up contact portion. B) It consists of a support shaft attached to the arm and a self-aligning rolling bearing externally mounted on the support shaft so that it can rotate.
The outer race of the self-aligning rolling bearing is used as the follow-up contact part. C) A ball support shaft whose outer peripheral surface is a convex spherical surface and which is attached to the arm, and a rolling bearing which has a concave spherical surface on the inner race surface and is slidably and tiltably inserted onto the ball supporting shaft. The outer race of the rolling bearing is the follow-up contact part. D) The support shaft that is passed through the accommodating hole that extends through the arm and the outer
Both sides in the width direction of the peripheral surface are cylindrical surfaces, and the widthwise center of the outer peripheral surface
Only the portion is a convex spherical surface, and the widthwise end faces of the roller are slidably externally inserted onto the support shaft so that both widthwise end surfaces of the roller are close to the accommodation hole. Particularly, the convex spherical surface of the roller is the follow-up contact portion. thing.

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.

[0015]

According to the variable valve mechanism of the present invention, the valve timing and the lift amount are continuously or stepwise changed from the low speed to the high speed of the internal combustion engine to meet the operating condition of the internal combustion engine. Precise control can be performed. Further, the displacement can smoothly and quietly be performed by the displacement of the camshaft, and further, one solid cam and one arm can be used for one valve.

[0016]

Embodiments of the variable valve mechanism in which the present invention is applied to both intake valves and exhaust valves will be described below with reference to the drawings. Therefore, in the embodiment, the term “valve” simply means both the intake valve and the exhaust valve.

First, FIGS. 1 to 7 show a variable valve mechanism according to a first embodiment. The camshaft 1 has a cam from a low rotation cam profile on the right side to a high rotation cam profile on the left side 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.
Since a has the same radius in both the low rotation cam profile and the high rotation cam profile, a is a cylindrical surface having no inclination. However, the nose portion 2b is inclined like a conical surface because the valve opening working angle and the lift amount are small in the low rotation cam profile and the valve opening working angle and the lift amount are large in the high rotation cam profile. There is.

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 operating conditions such as the number of revolutions of the internal combustion engine. The displacement device 3 includes a guide portion of the camshaft 1 using a spline and a drive portion of the camshaft 1 using hydraulic pressure (all are not shown), and is based on a rotation sensor of an internal combustion engine, an accelerator opening sensor, and the like. It is controlled by a control device (not shown) such as a microcomputer that operates as described above.

A swing arm 6 for opening and closing a valve 5 by swinging on the basis of a cam profile of a three-dimensional cam 2 is rotatably attached to a rocker shaft 4 arranged obliquely below the cam shaft 1. There is. The swing arm 6 has an insertion hole 7 for the rocker shaft 4 at its right end, a male screw pin 8 as a valve pressing portion and its fixing nut 9 at its left end, and is housed in the central part in a vertically extending manner. The hole 10 is provided with a roller mechanism 11 with a follow-up contact portion that comes into contact with the three-dimensional cam 2 while following the change in the contact line angle accompanying the rotation of the three-dimensional cam 2.

The roller mechanism 11 with the follow-up contact portion is provided in the accommodation hole 1
It is composed of a hollow support shaft 12 which is passed through 0 and is fixed to the swing arm 6 by crimping, and a spherical slide bearing 13 which is externally mounted on the hollow support shaft 12 so as to be slidably rotatable. The spherical plain bearing 13 is an inner race 1 whose outer peripheral surface is a convex spherical surface.
4 and an outer race 15 whose inner peripheral surface is a concave spherical surface and is slidably rotated and tiltably inserted into the inner race 14, and the outer race 15 serves as a contact portion for following the three-dimensional cam 2. There is. The outer race 15 is formed narrower than the inner race 14, and stopper rings 16 that prevent the outer race 15 from coming off are fitted in the grooves at both ends of the inner race 14.

The variable valve mechanism constructed as described above is
It works as follows. First, at low engine speed,
As shown in FIG. 4, the camshaft 1 is displaced leftward by the displacement device 3, and the low rotation cam profile on the right side of the three-dimensional cam 2 corresponds to the follower contact portion-equipped roller mechanism 11. Then, as shown in FIG. 4A, the base circular portion 2a
When the outer race 15 contacts the outer race 15, the contact line angle is parallel to the axis of the three-dimensional cam 2. Therefore, the outer race 15 does not incline with respect to the inner race 14, but contacts the base circular portion 2a. However, as shown in FIG. 4B, when the nose portion 2b comes into contact with the outer race 15, the contact line angle of the nose portion 2b is tilted, for example, about 10 degrees with respect to the axis of the three-dimensional cam 2. It tilts about 10 degrees with respect to and contacts the nose portion 2b well.

As described above, the outer race 15 tilts once for each revolution of the solid cam 2, contacts the solid 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 shown by the curve L in FIG. 6, the valves 5 on the exhaust side and the intake side are opened and closed with a small valve opening operating angle and lift amount, and low speed. Increases torque and fuel efficiency.

When the internal combustion engine is rotating at high speed, the camshaft 1 is displaced to the right by the displacement device 3 as shown in FIG. 5, and the left high-speed cam profile of the three-dimensional cam 2 follows the contact portion. It corresponds to the attached roller mechanism 11. Then, the outer race 15 is, as shown in FIGS.
The solid cam 2 tilts once for each rotation, contacts the solid 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 high rotation cam profile, and as shown by the curve H in FIG. 6, the valve 5 is opened and closed with a large valve opening angle and lift amount to increase the intake amount and high-speed output. Increase.

Even during the above low rotation to high rotation, the camshaft 1 is continuously displaced by the displacement device 3 according to the operating conditions such as the rotational speed and the accelerator opening, and the three-dimensional cam 2 is moved. The cam profile of the intermediate portion of the above corresponds to the roller mechanism 11 with the follow-up contact portion. Therefore,
The swing arm 6 swings based on its cam profile, and as shown by the curve M in FIG. 6, opens and closes the valve 5 with an intermediate valve opening operating angle and lift amount, thereby providing torque and output according to the operating condition. generate.

As described above, according to the variable valve mechanism of the first embodiment, the valve timing and the lift amount are continuously changed from the low speed to the high speed of the internal combustion engine to operate the internal combustion engine. Precise control according to the situation can be performed, and thus various characteristics such as torque, output, fuel consumption, and exhaust gas cleanliness can be maximized over the entire rotation range. In FIG. 7, the torque characteristic of the internal combustion engine obtained by the present embodiment is shown by a solid line, but the torque is increased over the entire rotation range as compared with the conventional variable valve mechanism shown by the above-mentioned dashed line. There are no valleys. It is considered that the fuel efficiency can be improved by about 15 to 20% at maximum, depending on the setting.

Further, the change can be smoothly and quietly performed by the displacement of the camshaft 1. Further, one solid cam 2 and one swing arm 6 can be used for one valve 5. The structure can be made simple and compact.

Next, FIG. 8 shows a variable valve mechanism of the second embodiment, in which the right end of the swing arm 6 is a hydraulic adjuster 18.
It differs from the first embodiment only in that it is swingably supported by an attached pivot 19.

Next, FIGS. 9 to 12 show a variable valve mechanism of the third embodiment, in which the rocker arm 2 is replaced with a swing arm.
It is different from the first embodiment only in that 0 is used. This rocker arm 20 is provided with a roller mechanism 11 with a follow-up contact portion at the right end, a male screw pin 8 as a valve pressing portion and its fixing nut 9 at the left end, and an insertion hole 7 for the rocker shaft 4 in the middle portion. ing. The cam shaft 1 and the three-dimensional cam 2 thereof are located below the roller mechanism 11 with a follow-up contact portion.

Unlike the swing arm, the rocker arm 20 swings like a seesaw, but except for this embodiment, it has the same operation as the first embodiment. FIG. 11 (a)
FIG. 4B shows the correspondence relationship between the three-dimensional cam 2 and the roller mechanism with follow-up contact portion 11 when the internal combustion engine is at low speed, and corresponds to FIGS. 4A and 4B of the first embodiment. Figure 12 (a)
5B shows the correspondence between the three-dimensional cam 2 and the roller mechanism with follow-up contact portion 11 when the internal combustion engine rotates at high speed, and corresponds to FIGS. 5A and 5B of the first embodiment.

Next, FIG. 13, FIG. 14, FIG. 15 and FIG.
6 and 17 show variable valve actuation mechanisms of the fourth, fifth, sixth and seventh embodiments, respectively, and a roller mechanism 11 with a follow-up contact portion is shown.
Only the specific configuration of the second embodiment differs from the first embodiment.

In the roller mechanism 11 with the follow-up contact portion of the fourth embodiment shown in FIG. 13, the outer race 15 is divided into two parts to form an inner race .
As well as easy extrapolated to race 14, both outer race 1
A cover ring 21 is attached by caulking to the outer periphery so that 5 cannot be separated.

The roller mechanism 11 with a follow-up contact portion of the fifth embodiment shown in FIG. 14 comprises a hollow support shaft 12 and a self-aligning rolling bearing 22 externally mounted on the hollow support shaft 12 so as to be slidably rotatable. The self-aligning rolling bearing 22 includes an inner race 23, rollers 24 (or balls), 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 follow-up contact portion of the sixth embodiment shown in FIG. 15 has a convex spherical outer surface, and has a ball support shaft 26 attached to the swing arm 6 and a ball support shaft 26 that slides around. The rolling bearing 27 includes a rolling bearing 27 that is movably and tiltably inserted, and the rolling bearing 27 includes an inner race 28 having an inner peripheral surface of a concave spherical surface, a roller 29 (or a ball), and an outer race 30. The race 30 is a follow-up contact part.

The roller mechanism with follow-up contact portion 11 of the seventh embodiment shown in FIGS. 16 and 17 has a hollow support shaft 12 and a convex spherical outer surface, and is slidably rotatable on the hollow support shaft 12 outside. The roller 31 is inserted, and the convex spherical surface of the roller 31 serves as a follow-up contact portion.

FIG. 16 shows the correspondence between the three-dimensional cam 2 and the roller mechanism 11 with the follow-up contact portion when the internal combustion engine is running at low speed. As shown in FIG. 3A, the base circle portion 2a
When the roller contacts the roller 31, the contact line angle is parallel to the axis of the three-dimensional cam 2, so that the top of the convex spherical surface of the roller 31 contacts the base circle 2a. Further, as shown in FIG. 3B, when the nose portion 2b comes into contact with the roller 31, the contact line angle is inclined with respect to the axis of the three-dimensional cam 2, so that the contact line angle slightly falls from the top of the convex spherical surface of the roller 31. The part makes good contact with the nose part 2b. FIG. 17 shows a correspondence relationship between the three-dimensional cam 2 and the roller mechanism 11 with the follow-up contact portion at the time of high rotation of the internal combustion engine. As shown in FIGS. The manner of contact with the spherical surface is the same as in FIGS. 16 (a) and 16 (b).

The same effects as those of the first embodiment can be obtained by the variable valve actuation mechanisms of the second to seventh embodiments. Further, the roller mechanism with follow-up contact portion 11 of the fourth, fifth, sixth and seventh embodiments can be applied to the rocker arm 20 of the second embodiment.

The present invention is not limited to the configuration of the above-described embodiment, but may be embodied with modifications within the scope not departing from the spirit of the invention, for example, as follows. (1) Displace the camshaft 1 in steps. (2) To appropriately change the configuration and control method of the displacement device 3.

[0038]

Since the variable valve mechanism of the present invention is configured as described above, the valve timing and the lift amount are changed continuously or stepwise from the low speed to the high speed of the internal combustion engine. As a result, precise control can be performed according to the operating condition of the internal combustion engine, and various characteristics such as torque, output, fuel consumption, and cleanliness of exhaust gas can be maximally improved over the entire rotation range. The above changes can be performed smoothly and quietly. Furthermore, one solid cam and one arm can be used for one valve, and the structure can be simplified and compact. Produce the effect.

[Brief description of drawings]

FIG. 1 is a perspective view showing a variable valve mechanism according to a first embodiment of the present 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 an IV-IV of FIG. 2 when the internal combustion engine is operating at low speed.
It is a line sectional view.

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

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

FIG. 7 is a graph showing a torque characteristic 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 front view showing a variable valve mechanism according to a third embodiment.

FIG. 10 is a plan view of the variable valve mechanism.

FIG. 11: XI-X of FIG. 9 when the internal combustion engine is operating at low speed
It is an I line sectional view.

FIG. 12: XI-X of FIG. 9 when the internal combustion engine is rotating at high speed
It is an I line sectional view.

FIG. 13 is a cross-sectional view of the main parts of the fourth embodiment.

FIG. 14 is a cross-sectional view of essential parts of a fifth embodiment.

FIG. 15 is a cross-sectional view of essential parts of a sixth embodiment.

FIG. 16 is a cross-sectional view of essential parts of a seventh embodiment of the internal combustion engine at low speed.

FIG. 17 is a cross-sectional view of an essential part of the internal combustion engine of the embodiment at a high rotation speed.

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

FIG. 19 is a graph showing a valve timing and a lift amount by another conventional variable valve mechanism.

[Explanation of symbols]

1 camshaft 2 three-dimensional cam 3 Displacement device 4 rocker shaft 5 valves 6 swing arm 8 Male screw pin 11 Roller mechanism with follow-up contact part 12 spindles 13 Spherical plain bearing Race within 14 15 Outer race 19 pivots 20 rocker arm 22 Self-aligning rolling bearing 25 outside race 26 ball spindle 27 Rolling bearing 28 Inner Race 30 outside race 31 Laura

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-18221 (JP, A) JP-A-6-280521 (JP, A) Actually open Sho-60-65307 (JP, U) Actually open 1- 159107 (JP, U) Actual exploitation Sho 57-97204 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01L 13/00 301 F01L 1/18 F16H 53/06

Claims (2)

(57) [Claims] 1. A camshaft provided with a three-dimensional cam in which the cam profile is continuously changed in the axial direction from a low-rotation cam profile to a high-rotation cam profile, and according to operating conditions such as the rotational speed of the internal combustion engine. A displacement device that displaces the camshaft continuously or stepwise in the axial direction, and an arm that opens and closes the valve by swinging based on the cam profile of the solid cam, the solid cam being provided on the arm. the follow-up contact portion with the roller mechanism that contacts the solid cam while following the change in the contact line angle caused by the rotation provided, the roller mechanism with follower contact portion, the outer peripheral surface of the convex spherical surface of
Ball support attached to the arm and inner race
The inner peripheral surface of the is a concave spherical surface and can be rotated by sliding on the ball support shaft.
It is composed of a rolling bearing that is externally and tiltably inserted.
The variable valve mechanism is characterized in that the outer race of the rolling bearing serves as a follow-up contact portion . 2. A cam profile for low rotation to a high rotation
Continuous cam profile in the axial direction up to cam profile
A camshaft having a three-dimensional cam that has been dynamically changed, and the camshaft according to the operating conditions such as the rotation speed of the internal combustion engine.
Displacement device that displaces the shaft continuously or stepwise in the axial direction
And swing based on the cam profile of the solid cam.
And an arm that opens and closes the valve by means of
Follow-up contact part that contacts the three-dimensional cam while following changes
A roller mechanism with a follow-up contact portion is provided through the arm.
The support shaft passed through the housing hole and the widthwise both sides of the outer peripheral surface are circular.
It is a cylindrical surface, and only the widthwise central part of the outer peripheral surface is a convex spherical surface.
The both end faces in the width direction are slidably and externally attached to the support shaft,
A roller adjacent to the accommodation hole,
The variable valve mechanism is characterized in that the convex spherical surface of is the follow-up contact part .