Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2001-05-30
2003-02-11
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090370
Reexamination Certificate
active
06516762
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a valve timing adjusting device in which the open-close timing of a suction valve and/or an exhaust valve of an internal-combustion engine (hereinafter, called an engine) is changed according to operation conditions of the engine.
2. Description of Related Art
Various valve timing adjusting devices have been proposed. In these devices, an open-close timing of a suction valve and/or an open-close timing of an exhaust valve in an engine are adjusted.
FIG. 7
is a horizontal sectional view of an internal structure of a vane type valve timing adjusting device having a plurality of conventional sealing units, and
FIG. 8
is a vertical sectional view taken along line A—A of FIG.
7
. In FIG.
7
and
FIG. 8
, referential numeral
1
indicates a housing. The housing
1
is connected with a crank shaft (not shown) denoting an output shaft of an engine through a chain (not shown). In the housing
1
, a sprocket
2
rotated with the crank shaft, a casing
3
having a plurality of shoes
3
a
and a cover
4
formed in an annulus ring shape are integrally formed with each other by using a plurality of fixing members
5
such as bolts. The shoes
3
a
protrude from an internal circumferential surface of the casing
3
so as to form a plurality of hydraulic oil chambers. A front side portion of the casing
3
is covered with the cover
4
. Also, a rotor
6
is arranged in the housing
1
to allow rotational motion relative to the casing
3
. The rotor
6
is fixed to a camshaft
7
by a fixing member
8
such as a bolt. Therefore, the rotational motion of the camshaft
7
relative to the output shaft of the engine is allowed. The camshaft
7
relates to an open-close operation of a suction valve or an exhaust valve. The rotor
6
has a plurality of vanes
6
a
. Each vane
6
a
partitions the corresponding hydraulic oil chamber surrounded by the corresponding shoes
3
a
of the casing
3
into a hydraulic oil chamber
9
for timing advance and a hydraulic oil chamber
10
for timing retard. Also, a plurality of first oil passages
11
and a plurality of second oil passages
12
are arranged in the camshaft
7
. Oil is supplied or discharged to/from each hydraulic oil chamber
9
for timing advance through the corresponding first oil passage
11
, and oil is supplied or discharged to/from each hydraulic oil chamber
10
for timing retard through the corresponding second oil passage
12
.
Also, to prevent oil leakage occurred between each hydraulic oil chamber
9
for timing advance and one hydraulic oil chamber
10
for timing retard adjacent to the hydraulic oil chamber
9
for timing advance, an axial directional slit
13
extending in an axial direction of the rotor
6
is formed in a top portion of the each shoe
3
a
of the casing
3
, an axial directional slit
14
extending in an axial direction of the rotor
6
is formed in a top portion of the each vane
6
a
of the rotor
6
, and a conventional sealing unit
101
is arranged in each axial directional slit
13
and axial directional slit
14
.
Each conventional sealing unit
101
is composed of a sealing member
102
formed of resin and a metallic plate spring
103
. Each sealing member
102
slides on an outer circumferential surface of the rotor
6
or an inner circumferential surface of the casing
3
, each metallic plate spring
103
pushes the corresponding sealing member
102
toward the outer circumferential surface of the rotor
6
or the inner circumferential surface of the casing
3
.
FIG. 9A
is a diagonal view showing a structure of the conventional sealing unit
101
not yet arranged in the valve timing adjusting device, and
FIG. 9B
is a diagonal view showing a structure of the conventional sealing unit
101
which has been already arranged in the valve timing adjusting device. As shown in FIG.
9
A and
FIG. 9B
, the sealing member
102
of each conventional sealing unit
101
has a seal reverse plane
102
a
parallel to a seal plane (not shown) and a pair of foot portions
102
b
protruding from both end portions of the seal reverse plane
102
a
, and the sealing member
102
is formed in a U-shaped section. The plate spring
103
of each conventional sealing unit
101
is composed of a central portion
103
a
formed in an arc shape and a pair of foot portions
103
b
placed on both ends of the central portion
103
a
. In this case, no connecting member is arranged to connect the sealing member
102
with the plate spring
103
. Therefore, in cases where the conventional sealing unit
101
is not arranged in the valve timing adjusting device, as shown in
FIG. 9A
, the sealing member
102
and the plate spring
103
are separated from each other. When the conventional sealing unit
101
is arranged in the valve timing adjusting device, as shown in
FIG. 9B
, the foot portions
103
b
of the plate spring
103
are put on the seal reverse plane
102
a
of the sealing member
102
, the valve timing adjusting device is laid down, and the sealing member
102
and the plate spring
103
are pushed into each axial directional slit
13
and axial directional slit
14
from the top while sliding on the surface of the slit. In this case, the height of the conventional sealing unit
101
is larger than a width of each axial directional slit
13
and axial directional slit
14
in a radial direction of the rotor
6
. Therefore, the central portion
103
a
of the plate spring
103
is pressed hard by the wall of each axial directional slit
13
and axial directional slit
14
, and the sealing member
102
and the plate spring
103
are substantially fixed to each other as a unit. Therefore, the sealing member
102
is pushed onto the outer circumferential surface of the rotor
6
or the inner circumferential surface of the casing
3
by the resilient force of the plate spring
103
, and the oil leakage between each hydraulic oil chamber
10
for timing retard and the corresponding hydraulic oil chamber
9
for timing advance can be prevented.
However, because the conventional sealing unit
101
of the valve timing adjusting device has the above-described structure, it is required to lay the plate spring
103
having a small size on top of the sealing member
102
and to insert the sealing member
102
and the plate spring
103
into each axial directional slit
13
and axial directional slit
14
of the valve timing adjusting device while setting the sealing member
102
and the plate spring
103
in a standing state. Assuming that the sealing member
102
and the plate spring
103
are inserted into each slit of the valve timing adjusting device by hand, it is possible to arrange the sealing member
102
and the plate spring
103
in the valve timing adjusting device. In contrast, in cases where it is desired to arrange the sealing member
102
and the plate spring
103
in the valve timing adjusting device by using an automatic system, it is required to hold each axial directional slit
13
and axial directional slit
14
by using a chuck. In this case, because an opening of each axial directional slit
13
and axial directional slit
14
is narrow, it is difficult to obtain a chuck holding space from each axial directional slit
13
and axial directional slit
14
. Therefore, it is difficult to reliably arrange the sealing member
102
and the plate spring
103
in the valve timing adjusting device. Also, in cases where the sealing member
102
and the plate spring
103
are fixed to each other by spot welding or screwing to make easy the arranging operation of the seal unit
101
, an elastic coefficient of the plate spring
103
is increased when the plate spring
103
is inserted into the axial directional slit
13
or
14
, and there is a problem that an excessive load is applied on the plate spring
103
.
Also, the conventional sealing unit
101
is frequently used in the valve timing adjusting device. Therefore, in cases where it takes a lot of time to arrange the sealing units
101
in the axial directional slits
13
and
14
respec
Hikita Minoru
Kinugawa Hiroyuki
LandOfFree
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