Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2003-10-29
2004-10-19
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090150, C464S001000, C464S015000, C464S035000
Reexamination Certificate
active
06805082
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon, claims the benefit of priority of, and incorporates by reference, the contents of Japanese Patent Application No. 2002-318836 filed Oct. 31, 2002.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a valve timing adjustment device for an internal combustion engine (hereinafter, “engine”) for adjusting the timing (hereinafter, “valve timing”) of at least one of an air intake valve and an exhaust valve.
2. Description of the Related Art
A conventional technique is known in which a valve timing adjustment device is provided to a transmission system for transmitting drive torque from a drive shaft (i.e., crankshaft) of an engine to a driven shaft (i.e., camshaft), to open and close an air intake valve and an exhaust valve of the engine, where the valve timing adjustment device adjusts the timing of the valves. According to the conventional technique, the valve timing adjustment device varies the rotational phase (below, simply “phase”) of the camshaft with respect to the crankshaft. Varying the phase in this way adjusts the valve timing, which may improve engine power output, fuel consumption, etc.
Patent Document 1 (Japanese Patent Publication No. 2001-41013) recites one example of a valve timing adjustment device. The recited device has a first rotor rotated by means of the camshaft drive torque, and a second rotor that rotates together with the camshaft in the same direction as the first rotor. In this configuration, the second rotor is rotated relative to the first rotor to vary the camshaft phase with respect to the crankshaft.
According to the valve timing adjustment device recited in Patent Document 1, a moveable operating member is moved along a radial direction of the first rotor and the second rotor, and a link is used to convert the radial movement of the moveable operating member into rotational movements by the two rotors as relative to each other. According to this construction, the degree of phase shift by the second rotor with respect to the first rotor (and, therefore, the degree of phase shift by the camshaft with respect to the crankshaft) is dependent upon the length of the arm constituting the link. However, the length of this link, which enables the conversion of the movement, is limited. As a result, the degree of phase shift possible by the camshaft with respect to the crankshaft is also limited.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a valve timing adjustment device that enables a great degree of freedom when setting the phase shift of a driven shaft with respect to a drive shaft.
According to a first aspect of a valve timing adjustment device of the present invention, a first hole in a first rotor forms a first track extending so as to vary its radial distance from a center rotation line, and the first hole makes contact with a control member passing through the first track, with the contact occurring on the two sides of the first hole toward which the first rotor rotates. Further, a second hole in a second rotor forms a second track extending so as to vary its radial distance from a center rotation line, and the second hole makes contact with the control member passing through the second track, with the contact occurring on the two sides of the second hole toward which the second rotor rotates. In addition, the first track and the second track slant toward each other in the rotational directions of the first rotor and the second rotor. Therefore, when the control means acts to change the control member's radial distance from the rotation centerline, the control member presses against at least one of the first hole and the second hole, whereby the control member passes through both the first track and the second track, and thus the second rotor is caused to rotate relative to the first rotor.
In the valve timing control device which operates in the foregoing manner, the degree of phase shift of the second rotor with respect to the first rotor is dependent upon the length of the first track and the second track and the degree to which the first track and the second track slant toward each other. By extending the first track and the second track such that they vary their radial distances from the rotation centerline, relative freedom is achieved in determining the length and the mutual slant of the tracks. In turn, this increases freedom in setting the degree of phase shift of the second rotor with respect to the first rotor, and therefore, the degree of phase shift of the driven shaft with respect to the drive shaft.
Note, however, that the mutually slanting first track and second track may be formed to intersect each other, or may also be formed in such that they do not intersect each other. According to a second aspect of the valve timing adjustment device of the present invention, the first rotor and the second rotor each have a plurality of pairs of the first hole and the second hole, arranged along the direction of rotation, such that each pair corresponds separately to each of a plurality of control members. Such a configuration alleviates unbalanced weight distribution around the rotation centerline.
According to a third aspect of the above-mentioned valve timing adjustment device of the present invention, an energizing means energizes one of the first rotor and the second rotor so as to advance that one rotor toward its direction of rotation, and energizes the other rotor so as to retard its movement toward its direction of rotation. A first wall portion formed to either the first rotor or the second rotor forms a first track extending so as to vary its radial distance from the rotation centerline, and the first wall portion makes contact with the control member passing through the first track in such a way that the contact occurs on the retardation side in terms of that rotor's direction of rotation.
Further, a second wall portion formed to the other rotor forms a second track extending so as to vary its radial distance from the rotation centerline, with the second wall making contact with the control member passing through the second track in such a way that the contact occurs on the advancement side in terms of the second rotor's direction of rotation. Here, the first track and the second track slant toward each other along the directions of rotation of the first rotor and the second rotor. Therefore, when the control means varies the control member's radial distance from the rotation centerline, the following operations occur in accordance with the direction in which the radial distance is being changed.
First, the energizing means causes the first wall portions and the second wall portions to be pressed against the control members, whereby the control members are caused to pass through the first track and the second track, and the second rotor is caused to rotate toward the advancement side or toward the retardation side relative to the first rotor. Second, at least one of the first wall portion and the second wall portion is pressed by the control member, whereby the control member is caused to pass through the first track and the second track, and the second rotor is caused to rotate toward the advancement side or toward the retardation side relative to the first rotor.
In the valve timing adjustment device operating in the foregoing manner, the degree of phase shift of the second rotor with respect to the first rotor is dependent upon the length of the first track and the second track and the degree to which the first track and the second track slant toward each other. By extending the first track and the second track such that each track varies its radial distance from the rotation centerline, relative freedom is achieved for setting the length and the mutual slant of the two tracks. In turn, this increases the degree of freedom in setting the degree of the phase shift of the second rotor with respect to the first rotor, and therefore, the degree of the phase shift of the driven
Inohara Takayuki
Takenaka Akihiko
Denion Thomas
Riddle Kyle M.
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