Valve timing adjusting device

Details Valve timing adjusting device Valve timing adjusting device

2001-07-10

2003-10-28

Lo, Weilun (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

With means for varying timing

C074S56800M

Reexamination Certificate

active

06637388

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a valve timing adjusting device in which an open-close timing of a suction (or intake) valve or an exhaust valve of an engine is changed according to operation conditions of the engine.
2. Description of Related Art
A prior-art example of a vane type valve timing adjusting device is disclosed in the Published Unexamined Japanese Patent Application H9-303118 (1997). In this valve timing adjusting device, a cam shaft is driven with a timing pulley or a chain sprocket which is rotated in synchronization with the rotation of a crank shaft of an engine, and a suction valve or an exhaust valve is opened or closed according to a phase difference based on a rotational movement of the cam shaft relative to the timing pulley or the chain sprocket.
FIG. 1
to
FIG. 3
are drawings respectively showing a vane type conventional valve timing adjusting device.
FIG. 1
is a vertical sectional view of the valve timing adjusting device, and FIG.
2
and
FIG. 3
are respectively sectional views taken substantially along line A—A of FIG.
1
.
FIG. 2
shows the valve timing adjusting device set in a position condition in which a cam shaft is placed at a maximally spark-lag (or timing-retarded) position in phase with respect to the rotation of a timing pulley, and
FIG. 3
shows the valve timing adjusting device set in a position condition in which a cam shaft is placed at a maximally spark-advance (or timing-advance) position in phase with respect to the rotation of a timing pulley. In
FIG. 1
,
1
indicates a valve timing adjusting device.
2
indicates a cam shaft for a suction valve. The cam shaft
2
is rotatably supported by a cylinder head (not shown). As shown in
FIG. 1
, a timing pulley
3
is arranged on a top portion of the cam shaft
2
to receive a rotational force of a crank shaft (not shown) of an engine through a belt or chain. An external rotor
5
is integrally fixed to the timing pulley
3
by using a plurality of bolts
4
to prevent a rotational movement of the timing pulley
3
relative to the external rotor
5
. A cover
6
is fixed to one end of the external rotor
5
by using the bolts
4
. In an internal opening of the external rotor
5
, an internal rotor
7
is arranged. A length of the internal rotor
7
in an axial direction of the cam shaft
2
is almost equal to that of the external rotor
5
. The internal rotor
7
is integrally fitted to the top portion of the cam shaft
2
by a bolt
9
so as to place the timing pulley
3
between a protruding portion
8
of the cam shaft
2
and the internal rotor
7
. In the inside of the cam shaft
2
, a spark-advance oil passage
10
and a spark-lag oil passage
11
are formed by drilling work so as to extend in the axial direction of the cam shaft
2
. The spark-advance oil passage
10
and the spark-lag oil passage
11
lead to an oil supply source (not shown) through an oil supply channel
12
and an oil discharge channel
13
which are arranged in a cylinder head (not shown).
As shown in FIG.
2
and
FIG. 3
, on the inner circumferential side of the external rotor
5
, five pressure chambers
15
and a supporting hole
16
are formed. The five pressure chambers
15
are partitioned by a plurality of portioning walls (or a plurality of shoes)
14
of the external rotor
5
, and the supporting hole
16
extends in a radial direction of the external rotor
5
. A leading hole
17
is arranged in near to the center of the bottom of the supporting hole
16
, and a diameter of the leading hole
17
is smaller than that of the supporting hole
16
. A slide pin
18
is inserted into the leading hole
17
. A slide pin supporting portion
19
is integrally formed with the slide pin
18
so as to be formed into the bottom portion of the slide pin
18
. A ring member
20
is fixedly attached to the outer circumferential surface of the supporting hole
16
, and a spring
21
is arranged in a position between the slide pin supporting portion
19
and the ring member
20
so as to press the slide pin
18
toward the inner circumferential side of the external rotor
5
. Here, the ring member
20
is inserted into the supporting hole
16
with a fixed force or is screwed to the outer circumferential surface of the supporting hole
16
to be fixed in the supporting hole
16
. Therefore, the ring member
20
functions as a supporting seat to fix one end of the spring
21
at a prescribed position.
On the outer circumferential surface of the inner rotor
7
, five vanes
22
are fitted to the inner rotor
7
so as to be placed in the five pressure chambers
15
respectively. Each vane
22
can be rotated in a circle-circumferential direction of the cam shaft
2
in the corresponding pressure chamber
15
, and the vanes
22
divide the five pressure chambers
15
into a group of spark-advance hydraulic oil chambers
23
,
24
,
25
,
26
and
27
and a group of spark-lag hydraulic oil chambers
28
,
29
,
30
,
31
and
32
. An oil pressure in each spark-advance hydraulic oil chamber
23
,
24
,
25
,
26
or
27
is adjusted by oil supplied or discharged through the spark-advance oil passage
10
and a spark-advance oil passage
33
,
34
,
35
,
36
or
37
. Also, an oil pressure in each spark-lag hydraulic oil chamber
28
,
29
,
30
,
31
or
32
is adjusted by oil supplied or discharged through the spark-lag oil passage
11
and a spark-lag oil passage
38
,
39
,
40
,
41
or
42
.
43
indicates a receiving hole. arranged in the internal rotor
7
. The slide pin
18
can be inserted into the receiving hole
43
.
44
indicates an oil passage leading to the receiving hole
43
. The oil passage
44
leads to the spark-advance oil passage
10
and the spark-advance oil passages
33
,
34
,
35
,
36
and
37
.
Next, an operation is described.
In the position condition shown in
FIG. 2
, the cam shaft
2
is placed at a maximally spark-lag position with respect to the rotation direction of the timing pulley
3
shown by an arrow of FIG.
2
. When the timing pulley
3
is rotated with a crank shaft (not shown), the rotational-force of the timing pulley
3
is transmitted to the cam shaft
2
, which can not rotate relative to the timing pulley
3
, through the slide pin
18
, and the cam shaft
2
is rotated in the rotation direction indicated by the arrow of FIG.
2
.
Here, the phase of each vane
22
can be changed in the rotation direction of the cam shaft
2
, and information relating to a rotation frequency in an engine and a driving power of the engine is sent to a control circuit (not shown). Therefore, in cases where it is judged in the control circuit that the advance of the cam shaft
2
in phase with respect, to the rotation of the timing pulley
3
is preferred, oil is supplied to the spark-advance oil passage
10
, oil of the spark-lag oil passage
11
is discharged, and the phase of the cam shaft
2
with respect to the timing pulley
3
is changed. More precisely, a control valve (not shown) leading to both the oil supply channel
12
and the oil. discharge channel
13
is controlled so as to supply oil to the spark-advance oil passage
10
. The oil supplied to the spark-advance oil passage
10
flows into the oil passage
44
, and the oil pushes the top portion of the slide pin
18
against the resilient force of the spring
21
. In the position condition shown in
FIG. 2
, the top end of the spark-advance oil passage
33
does not lead to the spark-advance hydraulic oil chamber
23
, and the top end of the spark-advance oil passage
37
does not lead to the spark-advance hydraulic oil chamber
27
. Therefore, the oil pressure in the oil passage
44
is necessarily increased by the oil which is supplied from the spark-advance oil passages
34
,
35
and
36
to the spark-advance hydraulic oil chambers
24
,
25
and
26
respectively, the slide pin
18
is pushed out from the receiving hole
43
, and each vane
22
moved with the cam shaft
2
is rotated in the rotation direction indicated by the arrow of FIG.
2
. When the cam shaft

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