Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2001-10-18
2002-09-10
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090370
Reexamination Certificate
active
06446590
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a valve timing control device, which modifies an open/close timing of an intake valve or an exhaust valve of an internal combustion engine (hereafter, referred as an engine).
2. Description of the Prior Art
Different kinds of devices are known as the conventional valve timing control devices (hereafter, referred as a VVT).
FIG. 1
is a lateral cross sectional view showing an internal construction of the conventional VVT disclosed in JP-A-1998/159515.
FIG. 2
is a longitudinal cross sectional view taken along lines A
1
—A
1
of FIG.
1
.
FIG. 3
is an enlarged cross sectional view taken along lines A
2
—A
2
of
FIG. 1
, showing a tier control member locking a free rotation of two rotational members.
FIG. 4A
is an enlarged cross sectional view taken along lines A
2
—A
2
of
FIG. 1
, showing the tier control member releasing the lock of the free rotation due to a release hydraulic pressure supplied from an advance side hydraulic pressure chamber.
FIG. 4B
is a plane view showing an area of a force-exerted face of the tier control member shown in FIG.
4
A.
FIG. 5A
is an enlarged cross sectional view taken along lines A
2
—A
2
of
FIG. 1
, showing the tier control member releasing the lock of the free rotation due to a release hydraulic pressure supplied from a retardation side hydraulic pressure chamber.
FIG. 5B
is a plane view showing an area of a force-exerted face of the tier control member in FIG.
5
A.
In the drawings, reference numeral
1
denotes a housing (first rotor) provided integrally a chain sprocket section
1
a
on which a rotational driving force of a crankshaft (not shown) of the engine. Numeral
2
denotes a case (first rotor) having a plurality of shoes
2
a
,
2
b
,
2
c
and
2
d
, which is located at the housing
1
, and which is projected inwardly to form a plurality of hydraulic pressure chambers. Numeral
3
denotes a rotor (second rotor) including a boss section
3
a
located at a central part of the rotor
3
and a plurality of vanes
3
b
,
3
c
,
3
d
and
3
e
formed at an outer peripheral surface of the boss section
3
a
. The boss section
3
a
is fixed at an end of a camshaft (not shown) with a bolt (not shown). The vanes
3
b
,
3
c
,
3
d
and
3
e
partition the plural hydraulic pressure chambers into advance side hydraulic pressure chambers
4
and retardation side hydraulic pressure chambers
5
. The advance side hydraulic pressure chamber
4
moves rotationally the second rotor with respect to the first rotor toward the advance side when a hydraulic pressure is supplied from an oil pump (not shown) of the engine via an oil control valve (not shown and hereafter referred as OCV). The retardation side hydraulic pressure chamber
5
moves rotationally the second rotor with respect to the first rotor toward the retardation side when the hydraulic pressure is supplied from the oil pun (not shown) via the OCV. A direction, which is indicated by arrow X
1
in
FIG. 1
, incidentally means a rotational direction of the camshaft (not shown).
Seal members
6
are disposed at ends of the shoes
2
a
,
2
b
,
2
c
and
2
d
of the case
2
and at ends of the vanes
3
b
,
3
c
,
3
d
and
3
e
of the rotor
3
, respectively. The seal member
6
creates a seal to block flow of actuating oil between the advance side hydraulic pressure chamber
4
and the retardation side hydraulic pressure chamber
5
to keep a hydraulic pressure in the respective hydraulic pressure chambers
4
and
5
. The seal member
6
includes a resilient seal
6
a
made of resin, and a leaf spring
6
b
, which biases the seal
6
a
against a seal-facing surface. The seal-facing surface means the outer region of the rotor
3
when the seal
6
is disposed at the case
2
, and means an inner region of the case
2
when the seal
6
is disposed at the rotor
3
, for example.
Numeral
7
denotes a cover (first rotor) closing an end of the rotor
3
, which opposes to the housing
1
. The cover
7
is integrally fixed at the housing
1
with a threaded bolt
8
passing through the shoes
2
a
,
2
b
,
2
c
and
2
d
of the case
2
. The housing
1
, the case
2
and the cover
7
constitutes the first rotor rotating in synchronization with the crankshaft (not shown).
A locative relationship between the first and second rotors is kept due to the adequate hydraulic pressure supplied to the advance side hydraulic pressure chamber
4
or the retardation side hydraulic pressure chamber
5
when the engine is usually operated. However, when the engine is stopped and a hydraulic pressure in the VVT is returned to an oil pan (not shown), the locative relationship between the first and second rotors is not kept due to the hydraulic pressure. Here, a beat noise (abnormal noise) results when the first rotor comes into contact with and separates from the second rotor over and over again as the engine is restarted. A lock pin (tier control member)
9
is arranged at the VVT in order to prevent the occurrence of the beat noise. The lock pin
9
locks a relative rotation of the first and second rotors when the engine is stopped or restarted, and allows the relative rotation when the engine is usually operated.
The lock pin
9
includes a front minor diameter section
9
a
, a central flange section
9
b
, a rear major diameter section
9
c
and a hollow section
9
d
as shown in
FIG. 2
to FIG.
5
B. The central flange section
9
b
has a diameter being larger than the front minor diameter section
9
a
, the rear major diameter section
9
c
has a diameter being larger than the central flange section
9
b
. The hollow section
9
d
is formed at a central portion of a bottom of the rear major diameter section
9
c
. The lock pin
9
is enclosed in an accommodation hole
10
, which is formed at the vane
3
b
of the rotor
3
in an axial direction (directions indicated by arrows Y
1
and Y
2
) of the VVT. A cylindrical holder
11
is press-fitted in the accommodation hole
10
before accommodating the lock pin
9
. The holder
11
includes a minor diameter section
11
a
, a major diameter section
11
b
and a tier section
11
c
defined as a boundary between the minor and major diameter sections
11
a
and
11
b
. The minor diameter section
11
a
has an inner diameter corresponding to the outer diameter of central flange section
9
b
of the lock pin
9
. The major diameter section
11
b
has an inner diameter corresponding to the outer diameter of the rear major diameter section
9
c
of the lock pin
9
. A coil spring (biasing member)
12
is arranged between the bottom of the accommodation hole
10
and the hollow section
9
d
of the lock pin
9
, and biases the lock pin
9
toward the housing
1
at all times. On the other hand, a fitting hole
13
is disposed at an end of the housing
1
facing to the rotor in the axial direction of the VVT, and allows fitting of the front minor diameter section
9
a
of the lock pin
9
. A first release hydraulic pressure chamber
14
is defined between the fitting hole
13
and the front minor diameter section
9
a
of the lock pin
9
, and communicates with the advance side hydraulic pressure chamber
4
at all times. The first release hydraulic pressure chamber
4
does not communicate with the retardation side hydraulic pressure chamber
5
due to the seal member
6
. A second release hydraulic pressure chamber
16
is defined between the rear major diameter section
9
c
of the lock pin
9
and the minor diameter
11
a
of the holder
11
within the accommodation hole
10
. The second release hydraulic pressure chamber
16
communicates with only the retardation side hydraulic pressure chamber
5
at all times via a retardation side communication passage
15
.
When the lock pin
9
moves backward due to the release hydraulic pressure, a rear space of the lock pin
9
defined in the accommodation hole
10
functions as a backward pressure chamber. A discharge hole
17
is formed at a rear portion of the accommodation hole
10
as shown in
FIG. 2
, and discharg
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