Valve-operating mechanism for internal combustion engine

Abstract

A valve-operating mechanism for an internal combustion engine having intake and exhaust valves and valve control members for controlling the intake and exhaust valves. The intake and exhaust valves are configured as dual valves having an outer valve and an inner valve. The valve control members, at least during scavenging, simultaneously close the outer valves of the intake and exhaust valves, producing a non-overlapping state, and simultaneously open the inner valves of the intake and exhaust valves, producing an overlapping state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Certain preferred embodiments of the present invention will be described in detail hereinafter with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view showing an internal combustion engine employing a valve-operating mechanism according to a first embodiment of the present invention;

FIG. 2 is a view showing the arrangement of the intake and exhaust valves of the valve-operating mechanism according to the first embodiment of the present invention;

FIG. 3 is a cross-sectional view showing an intake-side valve-operating mechanism and associated intake valve according to the first embodiment of the present invention;

FIGS. 4A and 4B are graphs showing the valve timing characteristics of the intake and exhaust valves of the valve-operating mechanism according to the first embodiment of the present invention, FIG. 4A showing the valve timing characteristics, FIG. 4B showing the valve timing characteristics in which the reference of the lift distance has been modified on the basis of FIG. 4A;

FIGS. 5A and 5B are schematic views illustrating the valve timing characteristics of the intake and exhaust valves of the valve-operating mechanism according to the first embodiment of the present invention, FIG. 5A showing the opening and closing states of the intake valve at the crank angle c5 in FIG. 4A, FIG. 5B showing the opening and closing states of the intake and exhaust valves at top dead center in the graphs of FIGS. 4A and 4B;

FIGS. 6A and 6B are diagrammatical views illustrating an operation of the intake-side valve operating mechanism according to the first embodiment of the present invention, FIG. 6A showing the inner valve and the outer valve of the intake valve being closed, and FIG. 6B showing the operation of opening of the inner valve;

FIG. 7A and 7B are diagrammatical views illustrating an operation of the intake-side valve operating mechanism according to the first embodiment of the present invention, FIG. 7A showing an operation that occurs until the outer and inner valves open, FIG. 7B showing the operation of closing of the outer valve;

FIG. 8 is a diagrammatical view showing an operation of the intake-side valve operating mechanism according to the first embodiment of the present invention;

FIG. 9 is a cross-sectional view illustrating an intake-side valve-operating mechanism and associated intake valve according to a second embodiment of the present;

FIG. 10 is a graph showing valve timing characteristics of the intake and exhaust valves of the valve-operating mechanism according to the second embodiment of the present invention;

FIGS. 11A is a graph showing timing characteristics of an intake valve of a valve-operating mechanism according to a third embodiment of the present invention, while FIG. 11B illustrates opening and closing actions of a pair of intake valves provided with an outer valve at the crank angle c12 of FIG. 1A;

FIG. 12 is a top plan view showing the mechanism for generating elastic force between an inner valve and an outer valve of a valve-operating mechanism according to a fourth embodiment of the present invention; and

FIG. 13 is a cross-sectional view showing an intake-side valve-operating mechanism and associated intake valve according to a separate embodiment of the present invention.

Claims

1. A valve-operating mechanism for an internal combustion engine having a cylinder head, a combustion chamber, and intake and exhaust ports, comprising: intake and exhaust valves adapted to be disposed in the cylinder head for respectively opening and closing the intake and exhaust ports which are designed to communicate with the combustion chamber, the intake and exhaust valves being configured as dual valves having an outer valve and an inner valve, the outer valve having an inner valve aperture extending axially thereof, the inner valve being movably fitted in the inner valve aperture, the outer valve having an inner channel that allows communication between the combustion chamber and the intake and exhaust ports, the inner channel being opened and closed by the inner valve; andvalve control members for controlling the opening and closing of the outer valve and inner valve, the valve control members, at least during scavenging, simultaneously closing the outer valves of the intake and exhaust valves to produce a non-overlapping state, and simultaneously opening the inner valves of the intake and exhaust valves to produce an overlapping state.

2. A valve-operating mechanism for an internal combustion engine having a cylinder head, a combustion chamber, and intake and exhaust ports, comprising: intake and exhaust valves adapted to be disposed in the cylinder head for respectively opening and closing the intake and exhaust ports that communicate with the combustion chamber, the intake and exhaust valves being configured as dual valves having an outer valve and an inner valve, the outer valve having an inner valve aperture extending axially thereof, the inner valve being movably fitted in the inner valve aperture, the outer valve having an inner channel that allows communication between the combustion chamber and the intake and exhaust ports, the inner channel being opened and closed by the inner valve; andvalve control members for controlling the opening and closing of the outer valve and inner valve, the valve control members respectively opening the outer valve and the inner valve of the exhaust valve in an exhaust stroke and respectively opening the outer valve and inner valve of the intake valve in an intake stroke.

3. A valve-operating mechanism for an internal combustion engine having a cylinder with a cylinder head, a combustion chamber, and intake and exhaust ports, comprising: a plurality of intake valves and an exhaust valve adapted to be disposed in the cylinder head radially relative to an axis of the cylinder for respectively opening and closing the intake and exhaust ports communicating with the combustion chamber; andvalve control members for preventing interference between the intake valves by controlling the opening and closing of the intake valves using different valve timings and different lift distances, respectively.

4. The valve-operating mechanism of claim 3, wherein either of the intake valves and the exhaust valve has a head portion of non-circular shape.

5. The valve-operating mechanism of claim 3, wherein the intake valves and exhaust valve are each configured as dual valves having an outer valve with an inner valve aperture passing axially therethrough, and an inner valve movably fitted in the inner valve aperture, the outer valve having an inner channel for allowing communication between the combustion chamber and the intake and exhaust ports, the inner channel being opened and closed by the inner valve, and the valve control members controlling the opening and closing of the outer valve and the inner valve.

6. A valve-operating mechanism for an internal combustion engine having a cylinder head, comprising: a camshaft adapted to be disposed in the cylinder head and having a valve-opening cam;an exhaust valve adapted to be disposed in the cylinder head;a valve-opening pushrod connected at one end to the camshaft in such a manner as to be driven by the valve-opening cam of the camshaft;a valve-opening rocker arm connected to an opposite end of the valve-opening pushrod and to the exhaust valve and swingably supported by a rocker shaft mounted to the cylinder head;a valve-closing pushrod connected at one end to the camshaft in such a manner as to be driven by a valve-closing cam of the camshaft; anda valve-closing rocker arm connected to an opposite end of the valve-closing pushrod and to the exhaust valve and swingably supported by the rocker shaft,wherein one of the valve-opening pushrod and the valve-closing pushrod is formed cylindrically, the other one of the valve-opening pushrod and the valve-closing pushrod is disposed inside the cylindrical pushrod such that the two pushrods are disposed substantially coaxially, so that rotation of the camshaft is converted via the pushrods and the rocker arms to opening/closing actions of the intake and exhaust valves.

7. A valve-operating mechanism for an internal combustion engine having a cylinder head, a combustion chamber, and intake and exhaust ports, comprising: intake and exhaust valves adapted to be disposed in the cylinder head for respectively opening and closing the intake and exhaust ports adapted to communicate with the combustion chamber, the intake and exhaust valves being configured as dual valves having an outer valve and an inner valve, the outer valve having an inner valve aperture extending axially thereof, the inner valve being movably fitted in the inner valve aperture, the outer valve having an inner channel that allows communication between the combustion chamber and the intake and exhaust ports, the inner channel being opened and closed by the inner valve; and a camshaft adapted to be disposed in the cylinder head, wherein the valve-operating mechanism further comprises:a first rocker shaft;an outer valve cam disposed on the camshaft;an outer valve first rocker arm that makes contact with the outer valve cam for opening and closing the outer valve, the outer valve first rocker arm being swingably supported by the first rocker shaft;an outer valve pushrod connected at one end to the outer valve first rocker arm;a second rocker shaft;an outer valve second rocker arm connected to an opposite end of the outer valve pushrod and to the outer valve and swingably supported by the second rocker shaft;an inner valve pushrod connected at one end to the inner valve first rocker arm; andan inner valve second rocker arm connected to an opposite end of the inner valve pushrod and to the inner valve and swingably supported by the second rocker shaft,the outer valve first rocker arm and the inner valve first rocker arm having respective drive arms for, when one of the rocker arms is driven by the outer valve cam or the inner valve cam, pushing the other one of the rocker arms to drive the same,one of the outer valve pushrod and the inner valve pushrod being formed cylindrically and the other one of the outer valve pushrod and the inner valve pushrod being disposed inside the cylindrical pushrod so that the two pushrod lie substantially coaxially,the outer valve being driven via the drive arms when the inner valve is opened and closed and the inner valve being driven via the drive arms when the outer valve is opened and closed, so that rotation of the camshaft is converted via the pushrods and the rocker arms to opening/closing actions of the intake and exhaust valves.

8. The valve-operating mechanism of claim 7, further comprising a spring provided between the outer valve and the inner valve for forcibly closing the inner valve against the outer valve.