Valve timing control device

Details Valve timing control device Valve timing control device

2001-06-26

2002-04-23

Lo, Wellun (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

With means for varying timing

Reexamination Certificate

active

06374788

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 are known as shown in
FIG. 1
to FIG.
4
.
FIG. 1
is a lateral cross sectional view of an internal construction of the conventional vane-type valve timing control device.
FIG. 2
is a longitudinal cross sectional view taken along lines A—A of FIG.
1
.
FIG. 3
is a longitudinal cross sectional view of the conventional lock-release mechanism of FIG.
2
.
FIG. 4
is an enlarged perspective view of main points of the lock-release mechanism in the conventional valve timing control device of FIG.
1
.
FIG. 5
is a graph of relation defined between stroke in operation of a lock member in the lock-release mechanism of FIG.
2
and FIG.
3
and oil pressure. In
FIG. 2
, a right hand direction denotes forward, and a left hand direction denotes backward. In FIG.
2
and
FIG. 3
, a lower side denotes forward, and an upper side denotes backward.
In the drawings, reference numeral
1
denotes a first rotor which connects with a crankshaft (not shown) of the engine through chains (not shown) or belts (not shown) to rotate in synchronization with the crankshaft (not shown). The first rotor includes a sprocket
2
, a case
3
and a cover
4
, which are integrated with a threaded member
5
such as a bolt and so on. The sprocket
2
rotates in conjunction with the crankshaft (not shown). The case
3
has a plurality of shoes
3
a
, which are projected from an inner portion of the case
3
to constitute a plurality of oil hydraulic pressure chambers between the shoes
3
a
. The cover
4
covers the oil hydraulic pressure chambers constituted by the shoes
3
a
of the case
3
.
A rotor (second rotor)
6
is arranged within the case
3
, and allows relative rotation with respect to the first rotor
1
. The rotor
6
is fixedly integrated with a camshaft
7
by using a threaded member
8
such as a bolt and so on, and the camshaft
7
relates to open/close of an intake valve or an exhaust valve. The rotor
6
has a plurality of vanes
6
a
of dividing the hydraulic pressure chambers above into an advance side oil hydraulic pressure chamber
9
and a retardation side oil hydraulic pressure chamber
10
. A first oil path .(pressure supply path)
11
and a second oil path (pressure supply path)
12
are arranged within the camshaft
7
. The first oil path
11
performs supply of oil hydraulic pressure to and discharge thereof from the advance side oil hydraulic pressure chamber
9
. The second oil path
12
performs supply of oil hydraulic pressure to and discharge thereof from the retardation side oil hydraulic pressure chamber
10
.
Seal means
13
are arranged on both of front ends of the shoes
3
a
of the case
3
and the vanes
6
a
of the rotor
6
, respectively. The respective seal means
13
prevents leakage of oil between the both of the oil hydraulic pressure chambers
9
and
10
. The seal means
13
includes a seal member
13
a
of sliding on an inner wall face of the oil hydraulic pressure chambers
9
and
10
, and a plate spring
13
b
of biasing the seal member
13
a
toward the inner wall face.
An accommodation hole
14
is arranged at one of the vanes
6
a
of the rotor
6
which acts as the second rotor. A lock pin (lock member, lock mechanism)
15
having a cylindrical shape is accommodated in the hole
14
to restrict relative rotation of the first rotor
1
and the second rotor. Since oil hydraulic pressure in the valve timing control device is reduced on starting the engine, the rotor
6
vibrates in the rotational direction by a cam load applied to a cam (not shown) integrated with the camshaft
7
to repeat contact and separation between the first and second rotors. Therefore, the lock pin
15
is biased by an biasing member (lock mechanism)
16
such as coil springs to engage in an engagement hole will be explained hereafter, the biasing member
16
being arranged between a rear wall of the accommodation hole
14
and the lock pin
15
. A discharge hole (release mechanism) is formed with the accommodation hole
14
to discharge a backward pressure of the lock pin
15
.
On the other hand, an, engagement hole
18
is formed at the sprocket
2
which acts as the first rotor to allow insertion of the lock pin
15
when the rotor
6
positions at the most retardation with respect to the first rotor
1
.
A valve
19
is arranged at the vane
6
a
having the accommodation hole
14
. The valve
19
supplies selectively higher oil hydraulic pressure in the advance side oil hydraulic pressure chamber
9
and the retardation side oil hydraulic pressure chamber
10
to the engagement hole
18
to release engagement (hereafter, referred as lock) between the engagement hole and the lock pin
15
. The valve (release mechanism)
19
communicates with the engagement hole
18
through a first release oil hydraulic supply path (release mechanism)
20
formed in the said vane
6
a
of the rotor
6
and a second release oil hydraulic supply path (release mechanism)
21
formed at the sprocket
2
. The valve
19
communicates with the advance side oil hydraulic pressure chamber
9
through an advance side pressure partition path (release mechanism)
22
, and communicates with the retardation side oil hydraulic pressure chamber
10
through a retardation side pressure partition path (release mechanism)
23
.
Next, a release operation will be explained.
In a release operation, oil hydraulic pressure is supplied from an oil pump (not shown) to the engagement hole
18
through the chamber
9
or the chamber
10
, the valve
19
, the first release oil hydraulic supply path
20
and the second release oil hydraulic supply path
21
. Release oil pressure is supplied to a space defined between an inner wall of the engagement hole
18
and an outer wall of the lock pin
15
within the engagement hole
18
to press the lock pin
15
against the biasing force of the biasing member
16
. Thus, the lock pin
15
is moved backward in the accommodation hole
14
to release from the engagement hole
18
. Backward pressure of the lock pin
15
is discharged from the accommodation hole
14
through the discharge hole
17
to the outside of the valve timing control device. A front end of the lock pin
15
released from the engagement hole
18
is accommodated in the accommodation hole
14
to allow free rotation between the first and second rotors.
Since an area subjected to oil pressure is constant from a locked state of the lock pin
15
to the end of a released state, a discharge speed of the backward pressure is also constant. Since strokes in the operation of the lock pin
15
are determined by the biasing force of the biasing member
16
and the oil pressure force, a one-on-one relation is established in the stroke and applied oil pressure. Therefore, release oil pressure is equal to holding-release oil pressure of holding the released state.
Incidentally, when the engine is stopped, oil in the advance side oil hydraulic pressure chamber
9
and the retardation side oil hydraulic pressure chamber
10
moves downwardly to an oil-pan (not shown) through the first and second oil path
11
and
12
and so on. Therefore, air accumulates in pipe arrangement such as the respective oil hydraulic pressure chambers and the respective oil paths. When the engine is restarted with the state above, oil hydraulic pressure rises by the oil pump (not shown) and simultaneously accumulated air in the pipe arrangement is discharged at once. Thus, the air-mixing oil is applied in the valve timing control device to release instantly the lock pin
15
from the engagement hole
18
.
However, the following problems result from the above structure for a conventional valve timing control device.
When the air-mixing oil releases the lock on starting the engi

Affiliated with

Also associated with

Rating

Valve timing control device does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Valve timing control device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Valve timing control device will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2824561