Valve timing control apparatus

Abstract

In a guide groove of a guide rotator of a valve timing control apparatus, a stopper surface is planar and is positioned in an end of the guide groove. The stopper surface is engageable with a cylindrical outer peripheral surface of a movable body, which is received in the guide groove, to stop the movable body. An arcuate outer connection surface connects between the stopper surface and an outer guide surface and has a radius of curvature, which is smaller than that of the cylindrical outer peripheral surface of the movable body. An arcuate inner connection surface connects between the stopper surface and an inner guide surface and has a radius of curvature, which is smaller than that of the cylindrical outer peripheral surface of the movable body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with additional objectives, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which:

FIG. 1A is an enlarged schematic view showing one state of a movable body received in a guide groove of a valve timing control apparatus according to an embodiment of the present invention;

FIG. 1B is an enlarged schematic view showing another state of the movable body received in the guide groove of the valve timing control apparatus according to the embodiment;

FIG. 2 is a cross sectional view taken along line II-II in FIG. 3 schematically showing the valve timing control apparatus of the embodiment;

FIG. 3 is a cross sectional view taken along line III-III in FIG. 2;

FIG. 4 is a cross sectional view taken along line IV-IV in FIG. 2;

FIG. 5 is a cross sectional view taken along line V-V in FIG. 2;

FIG. 6 is a cross sectional view similar to FIG. 4 but showing another operational state;

FIG. 7A is an exaggerated illustrative view for describing characteristics of the valve timing control apparatus of FIG. 2;

FIG. 7B is anther exaggerated illustrative view for describing characteristics of the valve timing control apparatus of FIG. 2;

FIG. 8 is a diagram illustrating a fluctuating torque; and

FIG. 9 is a cross sectional view showing a modification of the valve timing control apparatus shown in FIG. 2.

Claims

1. A valve timing control apparatus of an internal combustion engine, which controls valve timing of at least one of an intake valve and an exhaust valve that are opened and closed by a camshaft driven by a torque transmitted from a crankshaft, the valve timing control apparatus comprising: a first rotator that is rotated synchronously with the crankshaft;a second rotator that is rotated synchronously with the camshaft;a guide rotator that has a guide groove, which is elongated and has a predetermined width;a movable body that is guided in the guide groove in a direction of elongation of the guide groove to move toward or away from a rotational axis of the guide rotator in response to rotation of the guide rotator; anda link mechanism that is coupled with the first rotator, the second rotator and the movable body to change a relative rotational phase between the first rotator and the second rotator in response to movement of the movable body, wherein:the movable body has a cylindrical outer peripheral surface; andthe guide groove includes: a stopper surface that is planar and is positioned in one of two opposed ends of the guide groove, which are opposed to each other in the direction of elongation of the guide groove, wherein the stopper surface is engageable with the cylindrical outer peripheral surface of the movable body in the direction of elongation of the guide groove to stop the movable body;an outer guide surface that is slidably engageable with the cylindrical outer peripheral surface of the movable body to guide the movable body and that is positioned on a radially outer side of the movable body in a radial direction of the guide rotator;an arcuate outer connection surface that connects between the stopper surface and the outer guide surface and has a radius of curvature, which is smaller than that of the cylindrical outer peripheral surface of the movable body;an inner guide surface that is slidably engageable with the cylindrical outer peripheral surface of the movable body to guide the movable body and that is positioned on a radially inner side of the movable body in the radial direction of the guide rotator; andan arcuate inner connection surface that connects between the stopper surface and the inner guide surface and has a radius of curvature, which is smaller than that of the cylindrical outer peripheral surface of the movable body.

2. The valve timing control apparatus according to claim 1, further comprising a drive means for driving the guide rotator to rotate the guide rotator by providing a rotational torque to the guide rotator, wherein: an outer diameter of the cylindrical outer peripheral surface of the movable body is smaller than the width of the guide groove;when the movable body is moved toward the rotational axis of the guide rotator, the link mechanism causes relative rotation of the second rotator relative to the first rotator in one of an advancing direction and a retarding direction; andwhen the movable body is moved away from the rotational axis of the guide rotator, the link mechanism causes relative rotation of the second rotator relative to the first rotator in the other one of the advancing direction and the retarding direction.

3. The valve timing control apparatus according to claim 2, wherein: the stopper surface of the guide groove is a first stopper surface of the guide groove;the arcuate outer connection surface of the guide groove is a first arcuate outer connection surface of the guide groove;the arcuate inner connection surface of the guide groove is a first arcuate inner connection surface of the guide groove; andthe guide groove further includes: a second stopper surface that is planar and is positioned in the other one of the two opposed ends of the guide groove, wherein the second stopper surface is engageable with the cylindrical outer peripheral surface of the movable body in the direction of elongation of the guide groove to stop the movable body;a second arcuate outer connection surface that connects between the second stopper surface and the outer guide surface and has a radius of curvature, which is smaller than that of the cylindrical outer peripheral surface of the movable body; anda second arcuate inner connection surface that connects between the second stopper surface and the inner guide surface and has a radius of curvature, which is smaller than that of the cylindrical outer peripheral surface of the movable body.

4. The valve timing control apparatus according to claim 2, wherein: the drive means includes an electric motor, which generates the rotational torque; andthe drive means transmits the rotational torque, which is generated by the electric motor, to the guide rotor.