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

2004-07-13

Denion, Thomas (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

With means for varying timing

C123S090160, C123S090170

Reexamination Certificate

active

06761138

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a valve timing control apparatus for controlling valve open/close timing (hereinafter referred to simply as the valve timing) at which an intake valve or an exhaust valve of an internal combustion engine is opened or closed in dependence on operating state or condition of the engine.
2. Description of Related Art
In the field of the internal combustion engines, there have been proposed various apparatuses which make it possible to controllably change the valve timing for the intake valve or the exhaust valve of the internal combustion engine (hereinafter also referred to simply as the engine). For better understanding of the present invention, background techniques thereof will first be described in some detail by reference to
FIG. 8
of the accompanying drawings which shows generally and schematically a structure of an internal combustion engine equipped with a conventional valve control apparatus.
Referring to
FIG. 8
, reference numeral
1101
denotes an internal combustion engine which includes an intake pipe
1104
equipped with an air cleaner
1102
for purifying the air sucked into the engine
1101
, an air-flow sensor
1103
for measuring the intake air quantity (flow rate of the intake air), a throttle valve
1105
for regulating the intake air quantity to control the output torque of the engine
1101
and a fuel injector
1106
for injecting an amount of fuel compatible with the intake air quantity.
Further, the engine
1101
is provided with a spark plug
1111
for generating sparks for firing the air-fuel mixture charged in a combustion chamber of the engine
1101
, an ignition coil
1110
for supplying a high-voltage energy to the spark plug
1111
, an exhaust pipe
1107
for discharging an exhaust gas resulting from combustion of the air-fuel mixture, an O
2
-sensor
1108
disposed in the exhaust pipe
1107
for detecting a residual amount of oxygen contained in the exhaust gas, and a three way catalytic converter
1109
capable of purifying concurrently harmful gas components contained in the exhaust gas such as THC, CO and NO
x
.
A sensor plate
1116
having a tooth or projection (not shown) formed at a predetermined position is mounted on a crank shaft (not shown either) corotatably therewith for detecting the crank angle (angular position of the crank shaft) in cooperation with a crank angle sensor
1115
which is so designed as to generate a signal upon every passing-by of the projection (not shown) of the sensor plate
1116
for detecting the crank angle (angular position of the crank shaft).
Further provided are a cam phase actuator
1113
for changing a relative angle of a cam shaft relative to the crank shaft and a cam angle sensor
1112
for generating a pulse signal upon passing-by of a projection of a cam angle detecting sensor plate (not shown) to thereby detect the cam angle in a similar manner as the crank angle sensor
14
described above.
Provided in association with the cam phase actuator
1113
are an oil control valve (hydraulic pressure regulating means)
1114
for regulating hydraulic pressure applied to the cam phase actuator
1113
to thereby control the relative angle (cam phase) of the cam shaft relative to the crank shaft and an ECU (electronic control unit serving as arithmetic means as well)
1117
which is in charge of controlling the cam phase in addition to an overall control of operation of the internal combustion engine
1101
.
Further provided are an oil pump
1118
for generating a hydraulic pressure to drive the cam phase actuator
1113
while feeding a lubricating oil under pressure to mechanical constituent parts of the internal combustion engine
1101
and a hydraulic pressure sensor
1119
for detecting the hydraulic pressure of the lubricating oil fed under pressure to the oil control valve
1114
from the oil pump
1118
.
Additionally, the engine is provided with an oil temperature sensor
1120
for detecting temperature of the oil fed under pressure from the oil pump
1118
to the oil control valve
1114
and a water temperature sensor
1122
for detecting temperature of cooling water
1121
employed for cooling the engine
1101
.
As a typical one of the hitherto known valve timing control apparatus (cam phase actuator)
1113
for the engine
1101
, there can be mentioned the apparatus shown in
FIGS. 9
to
13
of the accompanying drawings, in which
FIG. 9
is a view showing an internal structure of a conventional vane-type valve timing control apparatus, and
FIG. 10
is a vertical sectional view of the same taken along a line A—A shown in FIG.
9
.
Further,
FIG. 11
is an enlarged perspective view showing a major portion of a lock/unlock mechanism of the conventional vane-type valve timing control apparatus and
FIGS. 12 and 13
are vertical sectional views showing the lock/unlock mechanism, respectively.
Next, referring to
FIGS. 9
to
13
, description will be made of the conventional valve timing control apparatus
1113
.
Referring to the figures, the cam phase actuator (valve timing control apparatus)
1113
includes a first rotor assembly (also referred to as the first rotor)
1
(
FIG. 10
) which is operatively coupled to the crank shaft (not shown) serving as the output shaft of the engine so that the first rotor assembly
1
rotates in synchronism with the crank shaft.
The first rotor assembly
1
is comprised of a sprocket
2
adapted to rotate together with the crank shaft, a case
3
having a plurality of projecting shoes
3
a
(
FIG. 9
) which project radially inwardly from the inner peripheral portion of the case
3
to thereby define a corresponding number of hydraulic chambers, and a cover
4
(
FIG. 10
) for fluid-tightly closing the hydraulic chambers constituted by the projecting shoes
3
a
of the case
3
, wherein the sprocket
2
, the case
3
and the cover
4
are secured together by means of clamping members
5
such as bolts or the like (
FIGS. 9
,
10
) in an integral structure.
Disposed within the case
3
rotatably relative to the first rotor assembly
1
is a rotor (second rotor)
6
(
FIG. 9
) which is integrally secured to the cam shaft
7
by means of a clamping member
8
such as a bolt or the like (FIG.
10
). The cam shaft
7
constitutes a part of the mechanism for opening/closing the intake valve or the exhaust valve. The second rotor
6
includes a plurality of vanes
6
a
(
FIGS. 9 and 11
) each of which serves to partition each of the hydraulic chambers defined by the projecting shoes
3
a
, respectively, into a valve timing advancing hydraulic chamber
9
and a valve timing retarding hydraulic chamber
10
(FIG.
9
).
Further formed internally of the cam shaft
7
are first oil passages (hydraulic chamber feed passages)
11
through which hydraulic pressure is fed/discharged to/from the valve timing advancing hydraulic chambers
9
, respectively, and second oil passages (pressure chamber feed passages)
12
through which the hydraulic pressure is fed/ discharged to/from the valve timing retarding hydraulic chambers
10
, respectively. See FIG.
10
.
Disposed at a tip end portion of each of the projecting shoes
3
a
of the case
3
and a tip end portion of each of the vanes
6
a
of the second rotor
6
, respectively, are oil sealing means
13
for preventing occurrence of oil leakage between the valve timing advancing hydraulic chamber
9
and the valve timing retarding hydraulic chamber
10
(FIGS.
9
and
10
).
Formed in one of the vanes
6
a
of the second rotor
6
is a receiving hole
14
(
FIG. 10
) for receiving therein a lock pin. More specifically, a lock pin
15
(which may also be referred to as locking member or locking mechanism) which is implemented as a straight pin of a substantially cylindrical shape is disposed within the receiving hole
14
for the purpose of restricting relative rotation between the first rotor assembly
1
and the second rotor
6
(FIG.
10
).
In the engine starting phase or state in which no hydraulic pressure is effective internally of t

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