Valve timing control device

Details Valve timing control device Valve timing control device

2001-07-06

2002-05-07

Lo, Weilun (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

With means for varying timing

Reexamination Certificate

active

06382157

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 disclosed in JP-A-1997/280020 and JP-A-1999/210422, for example.
FIG. 1
is a perspective view of main points of the engine provided with the conventional valve timing control device mounted on an end of an intake camshaft.
FIG. 2
is a lateral cross sectional view of an internal construction of the conventional valve timing control device of FIG.
1
.
FIG. 3
is a longitudinal cross sectional view taken along lines A—A of FIG.
2
.
In the drawings, reference numeral
1
denotes a crankshaft (not shown) of the engine, and
2
denotes an intake camshaft integrated with a cam
3
controlling an open/close timing of an intake valve
4
.
5
denotes an exhaust camshaft integrated with a cam
6
controlling an open/close timing of an exhaust valve
7
.
8
denotes a valve timing control device (hereafter, referred as device) mounted fixedly at one end of the intake camshaft
2
,
9
denotes a sprocket mounted fixedly at one end of the exhaust camshaft
5
, and
10
denotes a sprocket mounted fixedly at one end of the crankshaft
1
.
11
denotes a chain which acts as an endless transfer member wound around the sprocket
10
, the sprocket
9
and a sprocket described later of the valve timing control device, turning clockwise (direction of arrow CW) in the drawings. A slit
2
a
is formed at the other end of the intake camshaft
2
, and a slit
5
a
is formed at the other end of the exhaust camshaft
5
. The slits
2
a
and
5
a
allow engagement of a positioning spacer
12
resulting an angle defined between the both camshafts.
Hereafter, the internal construction of the valve timing control device will be explained. In FIG.
2
and
FIG. 3
,
13
denotes a first rotor which connects with the crankshaft through the chain
11
to rotate in synchronization with the crankshaft
1
. The first rotor
13
includes a sprocket
14
rotating in synchronization with the crankshaft
1
, a case
15
having a plurality of shoes
15
a
which are projected from an inner portion of the case
15
to constitute a plurality of hydraulic pressure chambers, a cover
16
covering the hydraulic pressure chambers, and a threaded member
17
such as a bolt and so on integrating the sprocket
14
and the case
15
with the cover
16
.
A rotor (second rotor)
18
is arranged within the case
15
, and allows the relative rotation with respect to the first rotor
13
. The rotor
18
is fixedly integrated with the intake camshaft
2
, which relates to open/close operation of the intake valve
4
, through a washer
19
by using a threaded member
20
such as a bolt and so on. The rotor
18
has a plurality of vanes
18
a
dividing the hydraulic pressure chambers, which are constituted by the shoes
15
a
of the case
15
, into an advance side hydraulic pressure chamber and a retardation side hydraulic pressure chamber
22
. Moreover, a first oil path
23
and a second oil path
24
are arranged within the intake camshaft
2
. The first oil path
23
supplies hydraulic pressure to, and discharges a hydraulic pressure from the advance side hydraulic pressure chamber
21
. The second oil path
24
supplies hydraulic pressure to, and discharges a hydraulic pressure from the retardation side hydraulic pressure chamber
22
.
Seal means
25
are arranged on both of front ends of the shoes
15
a
of the case
15
and the vanes
18
a
of the rotor
18
, respectively. The respective seal means
25
includes a seal member
25
a
for sliding on an inner wall face of the advance side hydraulic pressure chamber
21
or the retardation side hydraulic pressure chamber
22
, and a plate spring
25
b
for biasing the seal member
25
a
toward the inner wall face.
An accommodation hole
26
is arranged at one of the shoes
15
a
of the case
15
acting as the first rotor
13
. A lock pin
27
having a cylindrical shape is accommodated in the hole
26
to restrict relative rotation of the first rotor
13
and the second rotor
18
. Incidentally, since hydraulic pressure in the valve timing control device is reduced on starting the engine, the rotor
18
vibrates in the rotational direction by a cam load applied to the cam
3
integrated with the intake camshaft
2
. When the first and second rotors
13
and
18
repeat contact and separation, and beat noise (abnormal noise) necessarily results. The lock pin
27
prevents the occurrence of the beat noise (abnormal noise). The lock pin
27
also keeps a required angle between the first and second rotors
13
and
18
under low hydraulic pressure being difficult to control the angle. Therefore, the lock pin
27
is biased by an biasing member
28
such as coil springs to engage in an engagement hole will be explained later, the biasing member
28
being arranged between a rear wall of the accommodation hole
26
and the lock pin
27
.
On the other hand, an engagement hole
29
is formed at the rotor
18
acting as the second rotor to allow insertion of the lock pin
27
when the first rotor
13
is positioned with respect to the rotor
18
at a required angle (maximum retardation).
A release valve
30
is arranged at the shoe
15
a
. The release valve
30
supplies selectively the higher hydraulic pressure in the advance side hydraulic pressure chamber
21
and the retardation side hydraulic pressure chamber
22
to a release hydraulic pressure chamber
99
to release engagement (hereafter, referred as lock) between the engagement hole
29
and the lock pin
27
. The release valve
30
communicates with the release hydraulic pressure chamber
99
through a release hydraulic supply path
31
. The release valve
30
and the advance side hydraulic pressure chamber
21
communicate with an advance side pressure partition path
32
, and the release valve
30
and the retardation side hydraulic pressure chamber
22
communicate with a retardation side pressure partition path
33
.
A recess
35
is formed at the rotor
18
acting as the second rotor to engage with a knock pin
34
which is arranged at one end of the intake camshaft
2
to define a relative rotation between the device
8
and the intake camshaft
2
.
Next, a method of assembling the valve timing control device will be explained.
At first, the valve timing control device is arranged at one end of the intake camshaft
2
. Here, the lock pin
27
is engaged with the engagement hole
29
to position fixedly the first rotor
13
of the device
8
and the rotor
18
acting as the second rotor at the required angle. The knock pin
34
of the intake camshaft
2
is further engaged with the recess
35
of the rotor
18
to position fixedly the intake camshaft
2
and the rotor
18
, in other wards, to fix the device
8
at a required angle. The sprocket
14
is connected fixedly to the rotor
18
positioned at the required angle by the threaded member
20
to position fixedly the sprocket
14
and one end of the intake camshaft
2
.
Next, the sprocket
9
is arranged at one end of the exhaust camshaft
5
. Here, a knock pin (not shown) of the exhaust camshaft
5
is engaged with a recess (not shown) to position the exhaust camshaft
5
and the sprocket
9
at a required angle. The sprocket
9
is fixed to the one end of the exhaust camshaft
5
by a bolt (not shown).
Next, as shown in
FIG. 1
, a crank-fixing pin
36
is screwed into the crankshaft
1
from the outside of the engine to position the crankshaft
1
at the required angle. The positioning spacer
12
is inserted into the slit
2
a
of the intake camshaft
2
and the slit
5
a
of the exhaust camshaft
5
to regulate the angle defined between the both camshafts.
Next, the chain
11
is wound around the sprocket
10
, the sprocket
9
, and the sprocket
14
, and is then held under a tension by a cha

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