Valve timing control apparatus for internal combustion engine

Details Valve timing control apparatus for internal combustion engine Valve timing control apparatus for internal combustion engine

2002-10-28

2004-05-11

Denion, Thomas (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

With means for varying timing

C123S090150, C074S56800M

Reexamination Certificate

active

06732689

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a valve timing control apparatus for controlling or regulating a valve open/close timing (hereinafter referred to simply as the valve timing) at which an intake valve and/or an exhaust valve of an internal combustion engine is opened and/or closed in dependence on operation state of the engine.
2. Description of Related Art
For having better understanding of the concept underlying the present invention, related techniques known heretofore will first be described in some detail by reference to
FIGS. 22
to
26
of the accompanying drawings which shows a conventional valve control apparatus for an internal combustion engine (hereinafter also referred to simply as the engine).
In the figures mentioned above,
FIG. 22
is a diametrical sectional view showing an internal structure of a vane-type valve timing regulating apparatus (which may also be referred to as the cam phase actuator),
FIG. 23
is a vertical sectional view of the same taken along a line A—A in FIG.
1
and shows a structure in an axial direction,
FIG. 24
is a partial perspective view showing a lock/unlock mechanism (lock pin retaining/releasing mechanism) and peripheral structure thereof in the cam phase actuator, and
FIGS. 25 and 26
are vertical sectional views showing in detail a structure of the lock/unlock mechanism including a lock pin which constitutes a major part thereof and a peripheral structure provided in association therewith in different operation states, respectively.
Referring to
FIGS. 22
to
26
, the valve timing regulating actuator includes a first rotor assembly
1
(also referred to as the first rotor) which is constituted by a sprocket
2
, a case
3
having a plurality of shoes
3
a
, a cover
4
, and clamping members
5
for securing together the sprocket
2
, the case
3
and the cover
4
, in an integral structure. The first rotor assembly
1
mentioned above constitutes a part of an external rotatable member such as a crank shaft of the engine. (See FIGS.
22
and
23
).
Disposed rotatably within the case
3
is a rotor (second rotor)
6
which constitutes an integral part of an internal rotatable shaft of the actuator and which includes a plurality of vanes
6
a
each of which is adapted to slideably move on and along the inner peripheral wall of the case
3
. (See
FIG. 23
)
The cam shaft
7
includes a clamping member
8
which extends along the rotational center axis of the cam phase actuator. The spaces defined between radially projecting shoes
3
a
of the case
3
and the vanes
6
a
of the second rotor
6
cooperate to form valve timing advancing hydraulic chambers
9
and valve timing retarding hydraulic chambers
10
, respectively. (See FIG.
23
).
Communicated to each of the valve timing advancing hydraulic chambers
9
and valve timing retarding hydraulic chambers
10
are a first oil passage (hydraulic chamber feed passage)
11
and a second oil passage
12
, respectively (FIGS.
22
and
23
).
A fluid-tight seal means
13
is provided at a tip end portion of the projecting shoe
3
a
of each vanes
6
a.
A pin receiving hole
14
having a back pressure chamber
14
a
defined therein is formed in one of the vanes
6
a
, and a lock pin (lock member)
15
is accommodated within the receiving hole
14
. The lock pin
15
is resiliently urged in a projecting direction (lock direction) under the influence of an urging means
16
such as a spring. (See FIG.
23
).
A discharging hole
17
is formed in the back pressure chamber
14
a
of the receiving hole
14
.
Communicated to the unlock hydraulic chamber
18
a
are a first unlocking hydraulic pressure feed passage
20
and a second unlocking hydraulic pressure feed passage
21
by way of a check valve
19
. Exchangeably provided on the upstream side of the check valve
19
are a valve timing advancing hydraulic pressure distribution passage
22
and a valve timing retarding hydraulic pressure distribution passage
23
, respectively. (See
FIGS. 25
,
26
).
Further formed in a side wall of the receiving hole
14
is a purge passage
24
(
FIGS. 25
,
26
) which serves to discharge through the discharging hole
17
the air trapped during stoppage of the engine, when the hydraulic pressure is fed from an oil pump (not shown) upon starting of engine operation.
By virtue of the arrangement that the air is forcibly discharged upon starting of the engine operation, a residual hydraulic pressure is generated by the oil supplied to the back pressure chamber
14
a
, whereby the unlocking of the lock pin
15
can positively be prevented (FIG.
25
).
On the other hand, when the advancing hydraulic pressure is put into effect, the urging effort of the urging means
16
is overcome by the hydraulic pressure fed from the oil pump, as a result of which the tip end portion of the lock pin
15
is pushed in the unlocking direction, whereby the lock pin
15
is released from the locked state (FIG.
26
).
FIG. 27
is a block diagram showing generally and schematically a structure of a conventional valve timing control apparatus for an internal combustion engine to which the present invention can find application.
Referring to
FIG. 27
, reference numeral
101
denotes generally an internal combustion engine which includes an air cleaner
102
for purifying the air sucked into the engine
101
, an air-flow sensor
103
for measuring an intake air quantity (flow rate of the intake air) fed to the engine
101
and an intake pipe
104
.
The intake pipe
104
is equipped with a throttle valve
105
for adjusting the intake air quantity (flowrate) to thereby control the output torque of the engine
101
and a fuel injector
106
for injecting an amount of fuel compatible with the intake air quantity.
Further, the internal combustion engine
101
is provided with an exhaust pipe
107
for discharging an exhaust gas resulting from combustion of the air-fuel mixture in the combustion chamber. Disposed within the exhaust pipe
107
are an O
2
-sensor
108
for detecting a residual amount of oxygen contained in the exhaust gas and a three way catalytic converter
109
.
The three way catalytic converter
109
serves to purify concurrently harmful gas components contained in the exhaust gas such as HC (hydrocarbon), CO (carbon monoxide) and NO
x
(nitrogen oxides).
Further, the engine
1101
is provided with a spark plug
111
adapted to be driven by an ignition coil
110
. The spark plug
111
serves to generate a spark for firing the air-fuel mixture charged in the combustion chamber of the engine with high-voltage energy supplied from the ignition coil
110
.
A cam angle sensor
112
provided in association with the intake valve of the engine
101
generates a pulse signal upon every passing of a projection formed in a cam angle detecting sensor plate (not shown) for thereby detecting the cam angle.
At this juncture, it should be mentioned that although only the cam angle sensor
112
provided in association with the intake valve is shown, this is only for the convenience of description. It should be understood that the cam angle sensor can of course be provided in association with the exhaust valve or both of the intake valve and the exhaust valve.
Provided in association with the intake valve and the exhaust valve of the engine
101
is a cam shaft for setting an intake/exhaust valve timing in synchronism with rotation of the crank shaft. The cam phase actuator
113
serving as the valve timing regulating means is provided in association with the cam shaft and so designed as to change the relative angle (cam phase) between the cam shaft and the crank shaft in the direction for advancing the valve timing (i.e., valve timing advancing direction) or in the direction of retarding the valve timing (i.e., valve timing retarding direction).
An oil control valve (hereinafter also referred to as OCV in abbreviation)
114
is so designed as to regulate the hydraulic pressure supplied to the cam phase actuator
113
to thereby control the cam phase of the cam shaft

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