Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2001-06-26
2002-04-30
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
Reexamination Certificate
active
06378477
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a valve timing control device for modifying the. opening and closing timing of the intake and exhaust valves in an internal-combustion engine (hereafter, referred as an engine) according to any operating condition.
2. Description of the Prior Art
Conventional valve timing control devices having various kinds of construction are provided as disclosed in JP-A-1998/159519 and JP-A-1998/159520, for example.
FIG. 1
is a lateral cross-sectional view of an internal construction of a conventional vane-type valve timing control device.
FIG. 2
is a longitudinal cross sectional view taken along lines A—A of FIG.
1
.
FIG. 3A
is an enlarged longitudinal cross sectional view of a release valve in the conventional valve timing control device shown in FIG.
1
and FIG.
2
.
FIG. 3B
is an enlarged lateral cross sectional view of the state of the release valve on application of advance hydraulic pressure. FIG.
3
C. is an enlarged lateral cross sectional view of the state of the release valve on application of retardation hydraulic pressure. In the drawings, reference numeral
1
denotes a pulley connected to a crankshaft (not shown) of the engine to rotate in conjunction with the crankshaft (not shown) through chains (not shown).
2
denotes a housing fixedly provided with the pulley
1
and having a bearing
2
a
used between the housing
2
and an intake camshaft or an exhaust camshaft (hereafter, referred as a camshaft).
4
denotes a case having a plurality of shoes
4
a
projected from an inner peripheral portion of the case
1
to constitute a plurality of hydraulic pressure chambers between the shoes
4
a.
5
denotes a cover for closing the hydraulic pressure chambers of the case
4
. The housing
2
, the case
4
and the cover
5
are integrated by a threaded member
6
such as bolts and so on. Here, the pulley
1
, the housing
2
, the case
4
and the cover
5
constitute a first rotor.
A rotor (second rotor)
9
is integrally locked on one end
3
a
of the camshaft
3
through a washer
7
by a threaded member
8
such as bolts and so, on. The rotor
9
is rotatably arranged within the first rotor. A plurality of vanes
9
a
is arranged an outer peripheral portion of the rotor
9
to divide the plurality of hydraulic pressure chambers into advance side hydraulic pressure chambers
10
and retardation side hydraulic pressure chambers
11
. A first oil path
12
and a second oil path
13
are arranged within the camshaft
3
. The first oil path
12
performs supplies of hydraulic pressure to and. discharges thereof from the advance side hydraulic pressure chamber
10
. The second oil path
13
supplies hydraulic pressure to and discharges hydraulic pressure from the retardation.side hydraulic pressure chamber
11
. Further, seal members i
4
are arranged on both front ends of the shoes
4
a
of the case
4
and the vanes
9
a
of the rotor
9
, respectively. The each seal member
14
includes a seal
14
a
and a plate spring
14
b
to prevent leakage of oil between the both hydraulic pressure chambers
10
and
11
.
A lock pin
15
having a substantially cylindrical shape is arranged on the housing
2
constituting the first rotor, and controls the relative rotation of the first and second rotors to prevent the following occurrence of beat noise (abnormal noise). Since a hydraulic pressure within the valve timing control device is reduced on starting the engine, the rotor
9
vibrates in the rotational direction as a result of a cam load applied to a cam (not shown) integrated with the camshaft
3
and thus the first and second rotors undergo repetitive contact and separation as a result of the vibration. Therefore, the lock pin.
15
can engage in an engagement hole as will be explained hereafter due to being biased by a biasing member
17
such as coil spring and so on, the biasing member
17
being arranged between a rear wall within a backward pressure chamber
16
and the lock pin
15
. The lock pin
15
includes a small radius part
15
a
inserted in the engagement hole, a large radius part
15
b
having an outer diameter substantial equal to an inner diameter of the backward pressure chamber
16
, and a hole
15
c
having a bottom therein. The hole
15
c
is formed in the large radius part
15
b
and supports one end of the biasing member
17
. A discharge hole
18
is formed in the backward pressure chamber
16
, the discharge hole
18
of discharging a backward pressure of the lock pin
15
. On the other hand, the engagement hole
19
for allowing insertion of the lock pin
15
.is formed in the vane
9
a
of the rotor
9
acting as the second rotor. The engagement hole
19
communicates with a release valve
21
through an oil hydraulic supply path
20
of supplying hydraulic pressure to release the lock pin
15
. As shown in
FIG. 3A
, FIG.
3
B and
FIG. 3C
, the release valve
21
includes a valve chamber
21
a
having an oval shape, a slide plate
21
b
having a circular shape in cross section, and a perforation hole
21
c
having an oval shape in cross section. The slide plate
21
b
is movable in a long radius direction in the valve chamber
21
a.
The perforation hole
21
c
is formed at a bottom of the valve chamber
21
a,
and communicates with the oil hydraulic supply path
20
. As shown in
FIG. 1
,
FIG. 3A
, FIG.
3
B and
FIG. 3C
, an advance side pressure partition path
22
communicates with the advance side hydraulic pressure chamber
10
and a retardation side pressure partition path
23
communicates with the retardation side hydraulic pressure chamber
11
. These paths
22
and
23
are connected to the valve chamber
21
a
of the release valve
21
. With the release valve
21
, when the pressure of the advance side hydraulic pressure chamber
10
is higher than that of the retardation side hydraulic pressure chamber
11
, as shown in
FIG. 3B
, the slide plate
21
b
moves toward the retardation side in the valve chamber
21
a.
Thus, the slide plate
21
b
closes the retardation side pressure partition path
23
, and communicates the advance side pressure partition path
22
to the oil hydraulic supply path
20
through the perforation hole
21
c
to supply the hydraulic pressure of the advance side hydraulic pressure chamber
10
thereto. On the other hand, when pressure of the retardation side hydraulic pressure chamber
11
is higher than that of the advance side hydraulic pressure chamber
10
, as shown in FIG.
3
A and
FIG. 3C
, the slide plate
21
b
moves toward. the advance side in the valve chamber
21
a.
Thus, the slide plate
21
b
closes the advance side pressure partition path
22
, and communicates the retardation side pressure partition path
23
to the oil hydraulic supply path
20
through the perforation hole
21
c
to supply the hydraulic pressure of the retardation side hydraulic pressure chamber
11
thereto.
Next, a release operation will be described.
When the lock is released, hydraulic pressure from an oil pump (not shown) is supplied to the engagement hole
19
through the advance side hydraulic pressure chamber
10
or the retardation side hydraulic pressure chamber
11
, the release valve
21
and the oil hydraulic supply path
20
. Thus, the lock pin
15
is moved backward in the backward pressure chamber
16
against the biasing force of the biasing member
17
. Here, the backward pressure of the lock pin
15
is discharged through the discharge hole
18
to the outside of the valve timing control device. With the discharge of the backward pressure, the area subjected to hydraulic pressure is constant from the locked state to the released state. When the small radius part
15
a
of the lock pin
15
is disconnected from the engagement hole
19
to be held in the backward pressure chamber
16
, the lock pin
15
is released to allow free rotation between the first and second rotors.
Incidentally, when the engine is stopped, oil in the advance side hydraulic pressure chamber
10
and the retardation side hydraulic pressure chamber
Fukuhara Katsuyuki
Kinugawa Hiroyuki
LandOfFree
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