Valve timing control device

Details Valve timing control device Valve timing control device

2001-09-25

2002-08-13

Lo, Weilun (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

With means for varying timing

Reexamination Certificate

active

06431132

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 at least one of an intake or an exhaust valve in an internal combustion engine (hereafter, referred as an engine) in response to any operating condition.
2. Description of the Prior Art
FIG. 1
is a longitudinal cross sectional view of a conventional valve timing control device.
FIG. 2
is a longitudinal cross sectional view taken along lines A—A of FIG.
1
.
In
FIG. 1
, reference numeral
1
denotes a camshaft opening and closing the intake and exhaust valves in the internal combustion. Numeral
2
denotes a housing, which is rotatably fitted in and held on the camshaft
1
. The housing
2
includes an input rotational member
3
constituted by a timing-sprocket or a timing-pulley inputting a rotational driving force from a crankshaft (not shown) of the engine to this device; and a cylindrical-shaped case
4
having a through hole, fixedly mounted on a side of the input rotational member
3
. A plurality of shoes
5
extend to a rotational center of the camshaft
1
, and are integrated into an inner circumferential face of the case
4
as shown in FIG.
2
.
Numeral
6
denotes a rotor, which is rotatably accommodated into the case
4
and is fixedly coupled to the camshaft
1
. The rotor
6
includes a boss
7
rotatably fitting into the camshaft
1
to act as a rotational body; and a plurality of vanes
8
equal to the number of shoes
5
, the respective vanes extending in a radial direction of the boss
7
. The rotor
6
is coupled to the camshaft
1
by using an axial bolt
9
to allow rotation integral with the camshaft
1
.
Numeral
10
denotes a cover member assembled at a side of the case
4
, the side being opposite to the side disposing the input rotational member
3
. Numeral
11
denotes a threaded member integrally securing the cover member
10
, the input rotational member
3
and the case
4
. The threaded member (hereafter, referred as a bolt)
11
passes through the cover member
10
, the input rotational member
3
and the case
4
in the axial direction. The bolt
11
has a head section
11
a
making contact with an outer side face of the cover member
10
, and a front side of the head section
11
a
is a threaded section allowing insertion into a part of the case
4
and the input rotational member
3
. The cover member
10
has a bolt through hole
10
a.
The case
4
has a bolt through hole
4
a
close to the cover member
10
; and a bolt threaded hole
4
b
close to the input rotational member
3
, wherein the hole
4
a
and the hole
4
b
are coaxial. The input rotational member
3
has a bolt threaded hole
3
a.
Numeral
12
denotes a first hydraulic passage arranged in the camshaft
1
and the rotor
6
to communicate with a retardation side hydraulic pressure chamber
14
as described later. Numeral
13
denotes a second hydraulic passage arranged in the camshaft
1
and the rotor
6
to communicate with an advance side hydraulic pressure chamber
15
as described later.
In
FIG. 2
, numeral
14
denotes a retardation side hydraulic pressure chamber moving the vanes
8
of the rotor
6
in a retardation direction due to a hydraulic pressure supplied. Numeral
15
denotes an advance side hydraulic pressure chamber moving the vanes
8
in an advance direction due to a hydraulic pressure supplied. Each chamber is constituted by a fan-tailed space defined between the case
4
and the rotor
6
and between the respective shoes
5
and the respective vanes
8
, wherein an actuating-oil is supplied to the fan-tailed space.
Numeral
16
denotes a seal member arranged at a front end of the respective shoes
5
of the case
4
. Numeral
17
denotes a rear-spring (a leaf spring) of the seal member
16
. Numeral
18
denotes a seal member arranged at a front endof the respective vanes
8
of the rotor
6
. Numeral
19
denotes a rear-spring (a leaf spring) of the seal member
18
. Each seal member creates a seal between the inner radius of the case
4
and a junction face of the vane
8
and between the perimeter of the boss
7
of the rotor
6
and a junction face of the shoe
5
to prevent communication between both chambers
14
and
15
.
Moreover, the housing
2
and the rotor
6
are locked or released due to a lock means (not shown) actuating according to the conditions. On locking, the housing
2
rotates in synchronization with the rotor
6
. on releasing, the housing
2
rotates relative to the rotor
6
.
Next, an operation will be explained.
When the inner combustion is operated, a rotational force of the crankshaft (not shown) of the inner combustion is transmitted to the input rotational member
3
. Thus, the input rotational member
3
rotates in synchronization with the housing
2
. Here, as the housing
2
and the rotor
6
are locked, the housing
2
and the rotor
6
are rotated in synchronization with the camshaft
1
. In this way, a cam (not shown) fixedly coupled on the camshaft
1
rotates to open and close the intake and exhaust valves of the engine. Here, a hydraulic pressure from a hydraulic pressure control system is selectively supplied to the retardation side hydraulic pressure chamber
14
or the advance side hydraulic pressure chamber
15
according to the conditions. In this way, the rotor
6
rotates due to a pressure difference between the retardation side hydraulic pressure chamber
14
and the advance side hydraulic pressure chamber
15
, and accordingly allows automatic controlling of the opening and closing timing of the intake and exhaust valve.
The conventional valve timing control device is constituted as described above. When the cover member
10
, the case
4
and the input rotational member
3
are integrated into the housing
2
, the bolt
11
is simply screwed in the bolt threaded hole
4
b
of the case
4
and the bolt threaded hole
3
a
of the input rotational member
3
via the bolt through hole
10
a
of the cover member
10
. As a result, there is a problem that the bolt
11
becomes loose or detaches due to the vibration caused by driving the internal combustion at high speed.
Concretely, as the bolt
11
becomes loose, a gap is defined between the junction faces between the input rotational member
3
and the case
4
and the junction faces between the case
4
and the cover member
10
. As a result, oil leaks from the retardation side hydraulic pressure chamber
14
or the advance side hydraulic pressure chamber
15
and results in adverse effects on the control of the opening and closing timing of the valves. In a worst scenario, if the bolt
11
continues to become loose, it may detach. If the bolt
11
detaches and falls into the engine room, there is a problem that the bolt
11
gets caught in the moving parts of the internal combustion. Furthermore, when the expansion coefficient of the housing
2
is different from that of the bolt
11
, the bolt
11
may become loose due to changes in temperature of the internal combustion. As a result, the leakage of oil from the retardation side hydraulic pressure chamber
14
or the advance side hydraulic pressure chamber
15
is increased and results in reduced performance in controlling the valve timing control device.
SUMMARY OF THE INVENTION
Accordingly, the present invention is made to resolve the problems above, and it is an object of the present invention to provide a valve timing control device, which ensures reliability of the device, and increases durability thereof, without loosening and detachment of a threaded member due to the vibration. The threaded member is used for coupling integrally components of the housing accommodating the rotor therein.
In order to achieve the object of the present invention, a valve timing control device comprises a camshaft opening and closing at least one intake and exhaust valves in an internal combustion; an input rotational member arranged on the camshaft to input the rotational driving force of the internal combustion; a case whose end is assembled in th

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