Valve timing adjusting device

Details Valve timing adjusting device Valve timing adjusting device

2001-09-25

2002-09-17

Lo, Weilun (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

With means for varying timing

C123S090650, C123S090670

Reexamination Certificate

active

06450138

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a valve timing regulation device which automatically varies the opening and closing timing of one or both of an intake valve and an exhaust valve in response to performance conditions of an internal combustion engine.
BACKGROUND ART
A conventional valve timing regulation device is already known which comprises a camshaft for opening and closing an intake valve and an exhaust valve of an internal combustion engine, a housing provided to rotate freely on the camshaft and driven to rotate by the output of the internal combustion engine, a rotor stored in the housing to be relatively rotatable and connected to the camshaft, and a lock means which operates with a mechanical urging force to restrict the relative, rotation of the housing and the rotor and which releases the restriction by the operation of a hydraulic control force (control hydraulic pressure) in a direction against the mechanical urging force.
FIG. 1
is a schematic cross sectional view showing the structure of a general internal combustion engine. In the figure, reference numeral
1
denotes a cylinder of an internal combustion engine,
2
is a piston which undergoes reciprocal motion in the cylinder
1
,
3
is a crankshaft which is rotated by the reciprocal motion of the piston
2
,
4
is a combustion chamber which combusts and explodes a gaseous mixture,
5
is an ignition plug which ignites the compressed gaseous mixture in the combustion chamber
4
with a spark,
6
is an air intake passage which supplies a gaseous mixture to the combustion chamber
4
,
7
is an exhaust passage which exhausts the gases combusted in the combustion chamber
4
,
8
is an intake valve which opens and closes the air intake passage
6
,
9
is an exhaust valve which opens and closes the exhaust passage
7
,
10
a
is a camshaft near the air intake. The air intake camshaft
10
a
has a cam
11
a
which drives the opening and closing of the intake valve
8
,
11
b
is a camshaft near the exhaust and has a cam
11
b
which drives the opening and closing of the exhaust valve
9
.
12
a
is a timing pulley or a timing sprocket near the air intake which is rotatably fitted and retained on the air-intake camshaft
10
a.
12
b
is a timing pulley or a timing sprocket near the exhaust which is rotatably fitted and retained on the exhaust camshaft
11
b.
13
is a timing chain or a timing belt which links the timing pulley or the timing sprocket
12
a,
12
b
with the crankshaft
3
.
A valve timing regulation device is provided in the air-intake camshaft
11
a
and the exhaust camshaft
11
b
of the internal combustion engine.
FIG. 2
is a cross sectional view in an axial direction of a first conventional valve timing regulation device as disclosed for example in JP-A-10-68306. The first conventional valve timing regulation device regulates the opening and-closing timing of the exhaust valve
9
in FIG.
1
. In
FIG. 2
, those components which are the same as or similar to those shown in
FIG. 1
are designated by the same reference numerals.
In
FIG. 2
, reference numeral
14
denotes a fixed camshaft sleeve securely fitted with a camshaft
10
b
near an exhaust (hereafter this will simply be referred to as camshaft). The timing pulley
12
b
near the exhaust is arranged rotatably on the camshaft
10
b
through the camshaft sleeve
14
. Thus, the camshaft
10
b
and the camshaft sleeve
14
rotate together. The timing pulley
12
b
rotates relative to the camshaft
10
b.
12
c
is a projection for catching the spring thereon, which is integrally formed on one face of the timing pulley
12
b
and projects therefrom.
15
is a spiral spring, an outer radial side end portion of which is hung on the projection
12
c
and an inner radial side end portion of which is hung on the camshaft sleeve
14
. The spiral spring
15
urges the rotor
18
(discussed hereafter) in an advancing direction, the urging force is set to be greater than the maximum torque when the internal combustion engine is started.
16
is a housing which is fixed by a bolt
17
on the timing rotation body
12
b,
16
a
is an annular partition which is formed in the middle of an inner peripheral surface of the housing
16
. An internal section of the housing
16
is partitioned by the partition
16
a
into a rotor storage chamber
16
b
on one axial end and a spring storage chamber
16
c
on the other axial end. The spiral spring
15
is stored in the spring storage chamber
16
c.
18
is a rotor which is rotatably stored in the rotor storage chamber
16
b
of the housing
16
. The rotor
18
is fixed with an axial bolt
19
to an end portion of the camshaft
10
b
and is adapted to rotate together with the camshaft
10
b.
Thus, the housing
16
and the rotor
18
can rotate relative to one another.
20
is a covering member which covers the open end of the housing
16
and is fixed with a bolt
21
to the housing
16
.
FIG. 3
is a cross sectional view of the first conventional valve timing regulation device along the line A—A in FIG.
2
. In the figure, reference numeral
22
denotes a plurality of shoes which project from an inner peripheral surface of the housing
16
. The shoes
22
are integrated with the housing
16
, the tips of the shoes
22
are in slide contact with the rotation body of the rotor
18
. Reference numeral
23
denotes a plurality of vanes which project from an outer peripheral surface of the rotor
18
and extend in a radial direction. These vanes are integrated with the rotor
18
, the tips of the vanes
23
are respectively in slide contact with the inner peripheral surface of the housing
16
between the shoes
22
. An advance hydraulic chamber
24
and a retard hydraulic chamber
25
each having a fan-shaped space is formed between the shoes
22
and the vanes
23
. A hydraulic oil is supplied from the hydraulic control system (not shown) to the advance hydraulic chamber
24
and the retard hydraulic chamber
25
in accordance with the operation condition of the internal combustion engine.
As described above, the first conventional valve timing regulation device is provided with a lock mechanism (not shown) for locking the rotor
18
at a maximum advance position with respect to the housing
16
. The lock mechanism includes a stopper which is contained in the rotor
18
to be displaceable in its axial direction and a stopper hole which is formed on a cover member to engage and disengage with the stopper. The lock mechanism is also provided with a valve timing regulation mechanism on the air intake side which regulates the opening and closing timing of the intake valve
8
in FIG.
1
. The lock mechanism of the intake side valve timing regulation device is adapted to lock the rotor at a maximum retard position in an opposite manner to that of the exhaust side valve timing regulation device.
Next, the operation of the first conventional valve timing regulation device will be described below.
Firstly, in
FIG. 1
, a rotational force of the crankshaft
3
is transmitted respectively to the intake side camshaft
11
a
and the exhaust side camshaft
11
b
through the timing pulleys
12
a,
12
b
by the timing belt
13
during operation of the internal combustion engine. At this time, the rotor
18
and the housing
16
as shown in FIG.
2
and
FIG. 3
are in a lock released state. The opening and closing timing of the intake valve
8
and the exhaust valve
9
in
FIG. 1
is regulated by the relative rotation of the housing
16
and the rotor
18
due to a pressure differential of the advance side hydraulic chamber
24
and the retard side hydraulic chamber
25
to which a hydraulic oil is supplied from the hydraulic control system in accordance with the operation condition of the internal combustion engine.
When the internal combustion engine is stopped after operating, a rotational reaction force in the retarding direction is generated respectively to the intake side camshaft ha and the exhaust side camshaft
11
b
shown in FIG.
1
. The lock position of the air-intake side camshaft
11
a
is set to a m

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