Variable valve apparatus of internal combustion engine

Details Variable valve apparatus of internal combustion engine Variable valve apparatus of internal combustion engine

2000-09-15

2001-10-09

Lo, Weilun (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

With means for varying timing

C123S090170, C074S56800M

Reexamination Certificate

active

06298813

ABSTRACT:

INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. 11-288121 filed on Oct. 8, 1999, including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a variable valve apparatus of an internal combustion engine and, more particularly, to an internal combustion engine variable valve apparatus including a phase variation actuator that varies the rotation phase of a camshaft and a cam displacement actuator that displaces the camshaft in the direction of a rotating axis of the camshaft.
2. Description of Related Art
Phase variation type variable valve apparatus capable of varying the relative rotation phase between a camshaft and a crankshaft, that is, an engine output shaft, are conventionally known. Such a phase variation type variable valve apparatus has a first rotating body that is connected to a drive-transmission wheel for transmitting rotation from the crankshaft, such as a cam sprocket, a cam pulley, or the like, so that the first rotating body is rotatable together with the drive-transmission wheel, and a second rotating body that is connected to the camshaft so that the second rotating body is rotatable together with the camshaft. The variable valve apparatus further has a phase variation actuator for turning the first and second rotating bodies relative to each other through the use of, for example, a vane construction or a gear connecting construction having helical splines. Using the actuator, the variable valve apparatus varies the relative rotation phase between the crankshaft and the camshaft so as to vary the valve timing of the engine valves that are opened and closed by rotation of the camshaft.
Also known is a cam displacement type variable valve apparatus that displaces a camshaft in the direction of a rotating axis thereof, the camshaft being provided with three-dimensional cams whose cam profile shape varies in the direction of the rotating axis. In the cam displacement type variable valve apparatus, the camshaft is displaced in the direction of a rotating axis thereof to change the cam profile of each three-dimensional cam at the site of contact with the valve lifter of the corresponding engine valve, by using an actuator (cam displacement actuator) of, for example, a hydraulic drive type or the like, whereby the characteristic of the engine valves is changed.
Furthermore, a variable valve apparatus having both a phase variation actuator and a cam displacement actuator as described above is disclosed in Japanese Patent Application Laid-Open No. 11-153009. In such a variable valve apparatus, it is necessary to connect a camshaft to the phase variation actuator so that the camshaft is slidable in the direction of a rotating axis thereof, in order to allow the cam displacement actuator to displace the camshaft.
FIG. 9
shows a sectional structure of a phase variation actuator and its peripheral portion of a variable valve apparatus having a phase variation type valve variable mechanism and a three-dimensional cam type variable valve mechanism.
As shown in
FIG. 9
, a cam sprocket
113
, a journal
114
and a phase variation actuator
119
are provided at a distal end portion of a camshaft
110
having a three-dimensional cam
111
. The cam sprocket
113
is a drive-transmission wheel that is drivingly connected by a chain to a crankshaft, that is, an engine output shaft of an internal combustion engine. The cam sprocket
113
is rotatably supported to the engine by the journal
114
. Rotation of the cam sprocket
113
is transmitted to the camshaft
110
via the phase variation actuator
119
.
The phase variation actuator
119
has an outer rotor (first rotating body)
121
that is connected to the cam sprocket
113
so that the outer rotor
121
is rotatable together with the cam sprocket
113
, and an inner rotor (second rotating body)
120
that is connected to the camshaft
110
so that the inner rotor
120
is rotatable together with the camshaft
110
. The outer rotor
121
is disposed radially outwardly of the inner rotor
120
(relative to the rotation axis) so that the outer rotor
121
and the inner rotor
120
have one and the same rotating axis and are rotatable relatively to each other.
The phase variation actuator
119
as shown in
FIG. 9
is a generally-termed vane type phase variation actuator. The phase variation actuator
119
turns the rotors
120
,
121
relative to each other based on adjustment of pressure of oil introduced into liquid chambers
123
provided in slide-contact portions of the inner rotor
120
and the outer rotor
121
. By changing the relative rotation phase between the cam sprocket
113
connected to the outer rotor
121
and the camshaft
110
connected to the inner rotor
120
, the phase variation actuator
119
changes the valve timing of the engine valves, which are opened and closed based on rotation of the camshaft
110
.
A distal end portion of the camshaft
110
is inserted into the inner rotor
120
of the phase variation actuator
119
so that the distal end portion is slidable along an inner peripheral portion of the inner rotor
120
in the direction of a rotating axis thereof. The inner periphery of the inner rotor
120
and the outer periphery of the camshaft
110
have splines
112
,
117
, respectively. Thus, the phase variation actuator
119
employs a connecting construction wherein via meshing of the splines
112
,
117
, the inner rotor
120
and the camshaft
110
are connected so that they are rotatable together and so that the camshaft
110
is allowed to be displaced in the direction of the rotating axis.
In the example shown in
FIG. 9
, the phase variation actuator
119
further has, inside thereof, a sub-gear
130
for preventing production of noises of tooth impacts between the splines
112
,
117
that would otherwise be caused by torque fluctuations on the camshaft
110
involved in the opening and closing of the engine valves. The sub-gear
130
is disposed between the distal end portion of the camshaft
110
and the inner rotor
120
.
An outer periphery of the sub-gear
130
has external splines
131
whose tooth trace extends in the direction of the rotating axis. An inner periphery of the sub-gear
130
has internal splines
132
whose tooth trace extends in a direction diagonal to the rotating axis. The sub-gear
130
is connected to the inner rotor
120
by meshing between the external splines
131
and the internal splines
117
formed in an inner periphery of the inner rotor
120
. The sub-gear
130
is connected to the camshaft
110
by meshing between the internal splines
132
and external helical splines
118
provided in an outer periphery of a distal end portion of the camshaft
110
.
The sub-gear
130
is urged in a direction of the rotating axis by an urging member
133
, such as a wave washer (a washer having undulations) or the like. Via the helical-splines
118
,
132
, the sub-gear
130
converts the force from the urging member
133
into forces in rotating directions, thereby urging the inner rotor
120
and the camshaft
110
in such directions as to turn relative to each other. In this manner, the sub-gear
130
eliminates backlashes between the splines
112
,
117
, thereby substantially preventing noises of impacts between spline teeth.
Thus, since the camshaft
110
and the inner rotor
120
of the phase variation actuator
119
are connected by meshing between the splines
112
,
117
extending in the direction of the rotating axis thereof, the camshaft
110
is allowed to be displaced in the direction of the rotating axis while the camshaft
110
and the inner rotor
120
are integrally rotatably connected.
However, if this connecting construction is adopted, there is a possibility that the phase variation actuator
119
may have an increased diameter because the camshaft
110
needs to be inserted into the phase variation actuator
119
and the splines
112
,
117
need to be formed for connection between the camshaft

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