JP2001329816A - Valve driving mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a desired valve opening timing and valve opening amount in a valve driving mechanism capable of continuously varying the valve opening timing and valve opening amount of a valve. SOLUTION: A rocker arm capable of rocking round a fixed axis is rocked to drive the valve to be opened and closed. The driving force for driving the valve to be opened and closed is generated. A rocking element rocked by the above driving force is provided. The rocking locus of the rocking element is regulated. The regulated rocking locus is variable. The valve is driven to open and close by rocking of the rocking element along the regulated rocking locus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a valve drive mechanism.

[0002]

2. Description of the Related Art A preferable amount of intake air from the viewpoint of improving the engine output with respect to the amount of air (hereinafter, intake amount) and the inflow speed (hereinafter, intake speed) flowing into a combustion chamber of an internal combustion engine, or improving exhaust emission. It is known that the intake air speed exists for each engine operating state. Therefore, there is an attempt to improve the engine output or improve the exhaust emission by appropriately changing the intake amount and the intake speed to preferable intake amounts and intake speeds for each engine operation state.
As one of the attempts, there is a technique of changing the opening timing and the opening amount of an intake valve of an internal combustion engine. This technique is disclosed in, for example, JP-A-8-232694.

[0003] The intake valve driving mechanism described in this publication mainly includes two cams, a rocker arm that can swing, and one roller. The roller is disposed so as to be sandwiched between the two cams and the rocker arm. The roller can slide on the rocker arm. When these two cams are rotated during engine operation, one cam tries to slide the rollers on the rocker arm and the other cam tries to restrict the movement of the rollers in a certain direction. It is arranged in. That is, these two cams are arranged in such a manner that the rollers are slid on the rocker arm while restricting the movement of the rollers in a specific direction during operation of the engine.
As a result, the roller urges the rocker arm by rotation of the cam during engine operation, thus rocking the rocker arm,
Thus, the intake valve is driven to open.

[0004] In the intake valve driving mechanism described in this publication, the relative rotational phase of the two cams can be changed. If the relative rotational phase of the two cams is changed, the swing trajectory of the roller is changed, thereby changing the opening timing and the opening amount of the intake valve.

[0005]

In the intake valve driving mechanism described in the above publication, the relative rotational phases of the two cams can be changed, and therefore, the relative rotational phases that can be taken by these cams are as follows. It is continuous. That is, the valve opening timing and the valve opening amount of the intake valve can be continuously changed. However, the fact that the relative rotational phase of the cam can be continuously changed means that a phase deviated from a desired rotational phase can be obtained. Therefore, unless the relative rotational phase of the two cams is accurately controlled to the desired relative rotational phase, the valve opening timing and valve opening amount deviate from the desired valve opening timing and valve opening amount. In particular, in the intake valve driving mechanism described in the publication, the point of action of the roller with respect to the rocker arm moves, so that the deviation increases as the roller moves away from the rocking axis of the rocker arm. This problem exists not only in a mechanism for driving an intake valve of an internal combustion engine, but also in a valve drive mechanism that is capable of continuously changing the valve opening timing and valve opening amount. It is.

Accordingly, an object of the present invention is to obtain a desired valve opening timing and valve opening amount in a valve drive mechanism capable of continuously changing the valve opening timing and valve opening amount. It is in.

[0007]

According to a first aspect of the present invention, there is provided a valve driving mechanism for opening and closing a valve by swinging a rocker arm swingable about a fixed axis. A driving force generating means for generating a driving force for driving the opening and closing, and a swing element which is swung by a driving force of the driving force generating means around a fixed swing axis on a rocker arm different from the fixed axis. Swing trajectory defining means for defining the swing trajectory of the swing element, wherein the swing trajectory defined by the swing trajectory defining means can be changed, and the swing trajectory defined by the swing trajectory defining means can be changed. The valve is opened and closed by the swing of the swing element along the movement trajectory. That is, the swing element is swung only around one fixed fulcrum on the rocker arm.

According to a second aspect, in the first aspect, the swing trajectory defining means is rotatable around a predetermined rotation axis, and the swing trajectory defining means is rotated around the predetermined rotation axis. To change the swing locus defined by the swing locus defining means. According to a third aspect, in the second aspect, the swing trajectory defining means has a wall surface curved so as to surround a predetermined rotation axis, and the swing trajectory of the swing element is defined by the curved wall surface. Stipulate.

According to a fourth aspect of the present invention, in the third aspect, the predetermined rotation axis is on the same axis as the fixed swing axis when the valve is fully closed, and the swing trajectory defining means is curved. A partial region of the wall surface is a partial cylindrical surface centered on the fixed swing axis when the valve is fully closed. According to a fifth aspect, in the third aspect, the swing element has a rotatable roller, and the roller rolls on the curved wall surface of the swing trajectory defining means when the swing element swings.

According to a sixth aspect, in the first aspect, the driving force generating means is a cam.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a valve driving mechanism according to the present invention will be described in detail with reference to the drawings. FIG. 1 shows an intake valve drive mechanism for opening and closing an intake valve as one embodiment of the valve drive mechanism of the present invention. In FIG. 1, 1 is an intake valve, and 2 is an urging means. The urging means 2 is a means for urging the intake valve 1 so that the intake valve 1 closes, and the urging means 2 of this embodiment is a coil spring. In addition, the intake valve driving mechanism of the present embodiment generally includes a driving force generating means 3, a swing element 4, a swing locus defining means 5, and a rocker arm 6.

The driving force generating means 3 is means for generating a driving force for driving the intake valve 1 to open and is a cam in this embodiment. The cam 3 is mounted on a camshaft 7. The camshaft 7 is rotated in one direction around the cam rotation axis Ac during the operation of the engine, as indicated by the arrow Dc in FIG. 1, so that the cam 3 is similarly rotated in the direction of the arrow Dc. The rotation direction of the cam is indicated by an arrow Dc.
May be reversed. Further, the cam 3 is moved from the cam rotation axis Ac to the cam 3.
6A, the lift amount of the cam 3 gradually increases from about -150 ° when the angle at which the lift amount is maximized is 0 ° as shown in FIG. 6A. However, it reaches a maximum at 0 ° and gradually decreases from 0 ° to + 150 °. Therefore, the lift amount of the cam 3 changes relatively slowly. That is, the cam 3 of the present embodiment
Is very wide.

The oscillating element 4 is a driving force generating means, that is, an element which is oscillated by the driving force generated by the cam 3. As shown in FIG. 2, the oscillating element 4 includes one central roller (hereinafter, referred to as a central roller) 8 and the central roller 8.
A pair of rollers (hereinafter referred to as side rollers) arranged on both sides of
9 and an arm 10. The center roller 8 and the side rollers 9 are mounted on a common roller shaft 11 so that they can freely rotate independently around the roller rotation axis Ar. The roller shaft 11 is supported by the arm 10 so that it can freely rotate around the roller rotation axis Ar. The arm 10 is supported by the rocker arm 6 so as to be able to swing around a swing element swing axis Am on the rocker arm 6. Therefore, the swing element 4 is supported by the rocker arm 6 so as to be able to swing around the swing element swing axis Am. Swing element swing axis Am
Is fixed to the rocker arm 6.

The rocker arm 6 is pivoted by a pivot, a lash adjuster or a rocking shaft (not shown) so as to be able to rock around a fixed rocker arm rocking axis Ara located at one end thereof. Zu) is supported. The other end of the rocker arm 6 is arranged so as to be able to contact the head 12 of the intake valve 1.

The swing trajectory defining means 5 is a means for defining the swing trajectory of the swing element 4, and in this embodiment, has a wall surface (hereinafter referred to as a curved surface) 13 which is curved into a specific shape. It is a control plate. The control plates 5 are arranged one by one corresponding to each side roller 9. Control plate 5
Is rotatable in both directions around a fixed control plate rotation axis Acp as indicated by an arrow Dcp in FIG.
Here, the control plate rotation axis Acp is on the same axis as the swing element swing axis Am when the intake valve 1 is fully closed. By rotating the control plate 5 around the control plate rotation axis Acp, the position of the control plate 5 can be changed. The curved surface 13 has a control plate rotation axis Acp.
It is curved around the control plate rotation axis Acp. The curved surface 13 extends from the position relatively far from the cam 3 toward the cam 3 over substantially 180 °. Further, the curved surface 13 is a partial cylindrical surface centered on a swing element swing axis Am when the intake valve 1 is fully closed in a certain range from a place relatively close to the cam 3. Element swing axis A when fully closed
The distance between m and the curved surface 13 decreases. The above-described side roller 9 is disposed at a position where it can come into contact with the curved surface 13. Note that the center roller 8 is arranged at a position where it can come into contact with the outer surface of the cam 3.

Next, the operation of the intake valve driving mechanism of this embodiment will be described with reference to FIGS. 1, 4 and 5. 1 shows an intake valve driving mechanism in a fully closed stage in which the intake valve 1 is not opened at all, FIG. 4 shows an intake valve driving mechanism in a valve opening start stage in which the intake valve 1 starts to be opened, FIG. 5 shows the intake valve driving mechanism in the fully opened stage in which the intake valve 1 is fully opened.

In the fully closed stage shown in FIG. 1, the swing element 4 is located at a position closest to the cam rotation axis Ac. That is, it is at the position pivoted to the far right in FIG. The cam 3 which comes into contact with the central roller 8 in the fully closed stage shown in FIG.
Is a partial cylindrical surface centered on the cam rotation axis Ac of the camshaft 7. That is, the lift amount of the cam 3 is zero, so that the swing element 4 is not swung at all,
Thus, the intake valve 1 is not opened at all. The swing element 4 is urged by urging means (not shown) so as to be in the fully closed stage shown in FIG. Therefore, the swing element 4
When the lift amount of the cam 3 increases, the cam 3 is swung toward the left side in FIG. 1 against the urging force of the urging means.
When the lift amount decreases, the urging force of the urging means follows the lift amount to cause the rightward swing in FIG. In the following description, the state shown in FIG. 1 is referred to as an initial state.

Next, at the valve opening start stage shown in FIG.
Is rotated from the position shown in FIG. 1 in the direction of arrow Dc, and the swing element 4 is swung around the swing element swing axis Am. During the transition from the fully closed stage shown in FIG. 1 to the valve opening start stage shown in FIG. 4, the lift amount of the cam 3 gradually increases. However, during the swinging of the swinging element swing axis Am and the swinging element 4 in the initial state, the side rollers 9
The distance between the point on the curved surface 13 and the swing element 4
Is equal to the distance between the oscillating element oscillating axis Am during the oscillating movement and a point on the outer surface of the side roller 9 that contacts the curved surface 13 during the oscillating movement of the oscillating element 4. Therefore, the rocker arm 6 is not swung, and the intake valve 1 is not opened.

Next, at the fully open stage shown in FIG. 5, the cam 3 is further rotated in the direction of the arrow Dc from the position shown in FIG. 4, and the swing element 4 further swings around the swing element swing axis Am. It has been impatient. The lift amount of the cam 3 also gradually increases during the transition from the valve opening start stage shown in FIG. 4 to the full opening stage shown in FIG. However, unlike the period from the fully closed stage shown in FIG. 1 to the valve opening start stage shown in FIG. 4, the side roller 9 during the swing of the swing element swing axis Am and the swing element 4 in the initial state. The distance between the point on the curved surface 13 that contacts the oscillating element 4 and the side roller that contacts the curved surface 13 during the oscillating movement of the oscillating element 4 and the oscillating element 4 9 is shorter than the distance between the points on the outer surface.
For this reason, from the valve opening start stage shown in FIG. 4 to the fully opened stage shown in FIG. 5, the swing trajectory of the side roller 9 is defined by the curved surface 13. That is, the movement of the side roller 9 in the specific direction is restricted by the curved surface 13. Therefore, the swinging element 4 pushes down the rocker arm 6 and swings the rocker arm 6 around the rocker arm swinging axis Ara, and thus the intake valve 1 is opened.

When the cam 3 is further rotated from the fully open stage shown in FIG. 5, the lift of the cam 3 gradually decreases. Therefore, the swing element 4 is caused to swing by the urging force of the urging means in the direction opposite to the above-mentioned direction, that is, toward the right side of the drawing, and eventually reaches the fully closed stage shown in FIG. This cycle is repeated during the operation of the engine, so that the intake valve 1 is opened and closed.

As described above, the control plate 5 is rotatable around the control plate rotation axis Acp.
When the control plate 5 is rotated around the control plate rotation axis Acp, the relative positional relationship between the control plate 5 and the swing element 4 changes. Therefore, the swing locus of the side roller 9 defined by the curved surface 13 also changes. That is, when the control plate 5 is rotated and the relative positional relationship between the control plate 5 and the swing element 4 is changed, the valve opening characteristic of the intake valve 1 is changed to a curve Cmax as shown in FIG. And the curve Cmin. Specifically, the period during which the intake valve 1 is open, the valve opening start timing, and the maximum valve opening amount can be changed. Thus, according to the present embodiment, the intake amount and the intake speed can be set to the desired intake amount and the intake speed.

It should be noted that the relative positional relationship between the control plate 5 and the oscillating element 4 depends on the relationship that can maximize the engine output or maximize the exhaust emission. Is experimentally obtained in advance for each engine operating state, and an optimal relationship is appropriately selected in accordance with the experimental result. For example, the control plate 5 is rotated so that the larger the required engine load is, the closer to the curve Cmax in FIG. 6B, and the smaller the required engine load becomes, the closer to the curve Cmin in FIG. 6B. Can be rotated.

Next, advantages of the above-described intake valve driving mechanism of the present embodiment will be enumerated below. In the present embodiment, there is an advantage in that the control plate 5 is made rotatable so that the intake amount and the intake speed can be set to a preferable intake amount and the intake speed from the viewpoint of improving the engine output or improving the exhaust emission. Further, the swinging element 4 for swinging the rocker arm 6 to open and drive the intake valve 1 can be swung only around one fulcrum fixed on the rocker arm 6, that is, swinging with respect to the rocker arm 6. There is also an advantage in that the action point of the moving element 4 is fixed. This is because, when the operation point moves, when the position of the control plate 4 is deviated from the expected position, especially when the operation point is far from the swing axis of the rocker arm 6, the deviation of the opening amount and the valve opening timing of the intake valve 1 may be different. This is because it is amplified. However, if the point of action of the swing element 4 with respect to the rocker arm 6 is fixed as in this embodiment, even if the position control of the control plate 4 is deviated, the opening amount and the opening timing of the intake valve 1 will be the expected opening. There is no large deviation from the valve amount or the valve opening timing.

Further, the swing element 4 for swinging the rocker arm 6 for driving the intake valve 1 to open the valve can be swung only around one fulcrum fixed on the rocker arm 6. There are also advantages. That is, since the fulcrum does not move, the entire intake valve driving mechanism can be configured compactly. Furthermore, the curved surface 13 of the control plate 4
There is also an advantage in that a part of the region is a partial cylindrical surface centered on the swing element swing axis Am in the initial state. That is, by making a partial region of the curved surface 13 a partial cylindrical surface, the swing element 4 can be moved in a range where the lift amount of the cam 3 is not zero.
Is swung, but the intake valve 1 can form a region that is not opened. Therefore, the rotation of the control plate 5 slightly around the rotation axis thereof is sufficient for the intake valve 1.
Can be immediately changed to a region where the intake valve 1 is opened. In other words, when the partial area of the curved surface 13 is a partial cylindrical surface as in the present embodiment, the responsiveness of changing the valve opening characteristics of the intake valve 1 increases.

There is another advantage in that a part of the curved surface 13 of the control plate 4 is a partial cylindrical surface centered on the swing element swing axis in the initial state. That is, the change curve of the lift amount of the cam 3 can be made relatively gentle. According to this, the change speed of the lift amount of the cam 3 can be made relatively slow by selecting the rotation position of the control plate 4. Therefore, the seating speed of the intake valve 1 can be made relatively slow. Especially when the engine is operating at low load, FIG.
It is advantageous to select the rotational position of the control plate 5 so that the intake valve 1 is opened as shown by the curve Cmin. That is, in general, the noise generated by the engine during the low load operation of the engine is relatively small, and the sitting sound occupies a relatively large ratio as a factor of the noise generation. However, at the time of engine low load operation, as shown by the curve Cmin in FIG.
If the valve is opened, the seating speed can be made very slow, and therefore the noise of the entire internal combustion engine can be reduced.

A low seating speed of the intake valve 1 means that the impact of the intake valve 1 on the cylinder head when the intake valve 1 is seated is relatively small. For this reason, the wear of the intake valve 1 and the cylinder head is reduced, and their life is prolonged. It is also advantageous that the swing element 4 is held between the curved surface 13 of the control plate 5 and the outer surface of the cam 3 while the swing element 4 is swung. That is, if the swing element 4 is held between the curved surface 13 and the outer surface of the cam 3, the swing of the swing element 4 causes an extremely large swing shaft (not shown) having the rocker arm swing axis Ara. The application of force is prevented.

As another embodiment, an intake valve driving mechanism as shown in FIG. 7 can be employed. In the embodiment shown in FIG. 7, the configuration of the control plate is different from the configuration of the control plate 5 of the above-described embodiment. That is, the control plate 5a of the embodiment shown in FIG. 7 has the slot 13a. The side roller 9a is inserted into the slot 13a. The side roller 9a moves in the slot 13a by the driving force of the cam 3. At this time, the swing locus of the side roller 9a is defined by the curved inner wall surface of the slot 13a, and swings the rocker arm 6 by the same mechanism as in the above-described embodiment. Of course, also in the embodiment shown in FIG. 7, the control plate is rotatable about the control plate rotation axis, and the control plate is rotated about the control plate rotation axis, so that the valve opening characteristic of the intake valve 1 is increased. Can be changed.

Further, the rotation phase of the cam 3 itself may be changed, and the rotation phase of the cam 3 may be changed according to the engine operating state. If the change in the rotation phase of the cam 3 and the change in the position of the control plate described above are combined, it is possible to more accurately secure the preferable valve opening characteristics of the intake valve 1 for each engine operating state. Although the mechanism for opening and closing the intake valve has been described above, the present invention is widely applicable to a mechanism for opening and closing the valve.

[0029]

According to the invention, the rocking element is rocked about a fixed rocking axis on the rocker arm. If the point where the driving force for driving the valve is applied is fixed to one as described above, even if the swing locus of the swing element is changed, even if the change deviates from the intended change, the valve is opened. The effect on the characteristics can be made relatively small. Therefore, a desired valve opening timing and valve opening amount can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a valve drive mechanism of the present invention.

FIG. 2 is a perspective view showing one embodiment of the valve drive mechanism of the present invention.

FIG. 3 is a view showing the valve drive mechanism at a stage advanced from the stage of FIG. 1;

FIG. 4 is a view showing the valve drive mechanism at a stage advanced from the stage of FIG. 2;

FIG. 5 is a diagram showing a relationship between a control plate and a swing element in detail.

FIG. 6 is a diagram showing a cam curve and a lift curve.

FIG. 7 is a view showing a valve drive mechanism of another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Intake valve 3 ... Cam 4 ... Swinging element 5 ... Control plate 13 ... Curved surface

Continued on the front page F term (reference) 3G016 AA06 AA19 BA36 BB11 BB17 BB22 CA10 CA16 CA25 DA08 GA00 GA01 3G018 AB04 BA11 DA03 DA10 DA85 EA35 FA06 FA07 GA02 GA04 GA14 GA23 GA32

Claims (6)

[Claims] 1. A valve driving mechanism for opening and closing a valve by swinging a rocker arm that can swing around a fixed axis, a driving force generating means for generating a driving force for opening and closing the valve, A rocking element that is rocked by a driving force of the driving force generating means around a fixed rocking axis on a rocker arm different from the fixed axis, and a rocking path defining a rocking path of the rocking element; Means, the swing trajectory defined by the swing trajectory defining means can be changed, and the valve is moved by swinging the swing element along the swing trajectory defined by the swing trajectory defining means. A valve drive mechanism characterized by being opened and closed. 2. The swing trajectory defining means is rotatable about a predetermined rotation axis, and the swing trajectory definition means is rotated about the predetermined rotation axis to thereby oscillate the swing trajectory. 2. The valve driving mechanism according to claim 1, wherein the swing locus defined by the dynamic locus defining means is changed. 3. The swing trajectory defining means has a wall surface curved so as to surround the predetermined rotation axis, and defines the swing trajectory of the swing element by the curved wall surface. The valve drive mechanism according to claim 2, wherein 4. The valve according to claim 1, wherein the predetermined rotation axis is on the same axis as the fixed swing axis when the valve is fully closed, and a part of the curved wall surface of the swing trajectory defining means is defined by the entire area of the valve. 4. The valve driving mechanism according to claim 3, wherein the valve is a partial cylindrical surface centered on the fixed swing axis when the valve is closed. 5. The swing element has a rotatable roller, and the roller rolls on a curved wall surface of the swing trajectory defining means when the swing element swings. Item 4. The valve drive mechanism according to Item 3. 6. The valve driving mechanism according to claim 1, wherein said driving force generating means is a cam.