Variable valve operating mechanism

Abstract

The present invention provides a variable valve operating mechanism which includes two valve operating members for opening and closing two valves individually, a drive cam provided on a single camshaft, two swing arms for transmitting a power of the drive cam to the valve operating members individually by swinging about a different axis to the camshaft, and a variable device for modifying a displacement of the swing arm per rotation of the drive cam in accordance with an operating condition of an internal combustion engine. The variable device includes a single control shaft, an actuator for driving the control shaft, and a cam device that operates in conjunction with the control shaft to dissimilate the displacement of the two swing arms.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a variable valve operating mechanism according to a first example of the present invention;

FIG. 2 is a sectional view of the variable valve operating mechanism seen from the left of FIG. 1;

FIG. 3 is a longitudinal sectional view showing a structure in the variable valve operating mechanism combining a swing arm, a rocker arm, a displacement arm, and a guide member;

FIGS. 4A and 4B are structural diagrams showing an action produced in the variable valve operating mechanism when the displacements of two swing arms are minimized;

FIGS. 5A and 5B are structural diagrams showing an action produced in the variable valve operating mechanism when the displacement of one of the swing arms is maximized;

FIGS. 6A and 6B are structural diagrams showing an action produced in the variable valve operating mechanism when the displacement of the other swing arm is maximized;

FIG. 7 is a characteristic diagram showing the relationship between a lift and a working angle of a valve in the variable valve operating mechanism;

FIG. 8 is a sectional view of a variable valve operating mechanism according to a second example of the present invention;

FIGS. 9A and 9B are structural diagrams showing an action produced in the variable valve operating mechanism thereof when the displacements of two swing arms are maximized;

FIG. 10 is a sectional view of a variable valve operating mechanism according to a third example of the present invention;

FIGS. 11A and 11B are structural diagrams showing an action produced in the variable valve operating mechanism thereof when the displacements of two swing arms are maximized;

FIG. 12 is a sectional view of a variable valve operating mechanism according to a fourth example of the present invention;

FIG. 13 is a sectional view of the variable valve operating mechanism seen from the left of FIG. 12;

FIGS. 14A, 14B, and 14C are structural diagrams of a variable cam in a variable valve operating mechanism thereof;

FIG. 15 is a valve characteristic diagram showing an action of the variable valve operating mechanism thereof;

FIGS. 16A, 16B, and 16C are structural diagrams of a cam in a variable valve operating mechanism according to a fifth example of the present invention;

FIG. 17 is a valve characteristic diagram showing an action of the variable valve operating mechanism; and

FIG. 18 is a sectional view showing a conventional variable valve operating mechanism.

Claims

1. A variable valve operating mechanism comprising: two valve operating members for opening and closing two valves individually;a drive cam provided on a single camshaft;two swing arms for transmitting a power of the drive cam to the valve operating members individually by swinging about a different axis to the camshaft; anda variable device for modifying a displacement of the swing arm per rotation of the drive cam in accordance with an operating condition of an internal combustion engine,the variable device comprising: a single control shaft;an actuator for driving the control shaft; anda cam device that operates in conjunction with the control shaft to dissimilate the displacement of the two swing arms.

2. The variable valve operating mechanism according to claim 1, wherein the cam device comprises two variable cams for driving the two swing arms individually, and the two variable cams are provided on the control shaft and are provided with cam surfaces having respectively different profiles.

3. The variable valve operating mechanism according to claim 2, wherein each cam surface of the two variable cams includes a maximum lift portion in an identical rotation section of the control shaft, and the both maximum lift portions are formed at equal heights from an axial center of the control shaft.

4. The variable valve operating mechanism according to claim 3, wherein the cam surfaces of the two variable cams are formed at different heights from the axial center of the control shaft in a different rotation section of the control shaft to the rotation section of the maximum lift portions.

5. The variable valve operating mechanism according to claim 2, wherein, in an identical first rotation section (S3) of the control shaft, each of the cam surfaces of the two variable cams comprises the maximum lift portion at which the respective valves reach a maximum lift, and in an identical second rotation section (S4) of the control shaft, which is adjacent to the first rotation section, the cam surface of one of the variable cams comprises continuous maximum lift portions for maintaining the maximum lift of the valve, and the cam surface of the other variable cam comprises a gradually decreasing lift portion for continuously decreasing the lift of the valve.

6. The variable valve operating mechanism according to claim 5, wherein, in an identical third rotation section (S5) of the control shaft, which is adjacent to the second rotation section, the cam surface of one of the variable cams comprises continuous maximum lift portions for maintaining the maximum lift of the valve, and the cam surface of the other variable cam comprises a minimum lift portion for halting the valve.

7. The variable valve operating mechanism according to claim 6, wherein, in an identical fourth rotation section (S6) of the control shaft, which is adjacent to the third rotation section, the cam surface of one of the variable cams comprises a gradually decreasing lift portion for continuously decreasing the lift of the valve, and the cam surface of the other variable cam comprises continuous minimum lift portions for halting the valve.