Oil control valve capable of preventing reduction in oil flow

Fluid handling – Systems – Multi-way valve unit

Reexamination Certificate

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Details

C137S625650

Reexamination Certificate

active

06371164

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an oil control valve for supplying hydraulic oil to a blade oil hydraulic actuator for controlling an intake valve or exhaust valve to open or close timely depending on the operating condition of an engine so as to control the oil level of the oil hydraulic actuator.
2. Description of the Related Art
FIG. 1
is a sectional diagram showing a blade oil hydraulic actuator according to the related art. Reference numeral
1
indicates an intake cam shaft (hereinafter, simply referred to as a cam shaft) provided with an intake cam
1
a.
Numeral
2
indicates a timing pulley provided at an end of the cam shaft
1
. Numeral
3
indicates an actuator coupled to the cam shaft
1
so as to control valve opening/closing timing. Hydraulic oil supplied to drive the actuator
3
is lubricating oil for the engine (not shown). The actuator
3
is driven by the hydraulic oil to vary a displacement angle of the cam shaft
1
so that the opening and closing timing of the intake valve (not shown) is continuously controlled. Numeral
4
indicates a bearing of the cam shaft
1
. Numeral
5
indicates a housing of the actuator
3
and is rotatably fitted to the cam shaft
1
.
Numeral
6
indicates a case secured to the housing
5
. Numeral
7
indicates a blade rotor connected to the cam shaft
1
by a bolt
8
and housed in the case
6
. The rotor
7
is rotatable with respect to the case
6
. Numeral
9
indicates a tip seal provided between the case
6
and the rotor
7
so as to prevent leakage of oil between oil hydraulic chambers bounded by the case
6
and the rotor
7
. Numeral
10
indicates a back spring formed of a flat spring for forcing the tip seal
9
to be in contact with the rotor
7
. Numeral
11
indicates a cover secured to the case
6
. Numeral
12
indicates a bolt securing the housing
5
, the case
6
and the cover
11
to each other. Numeral
13
indicates an O-ring. Numeral
14
indicates a plate. Numeral
15
indicates a bolt securing the plate
14
to the cover
11
. Numerals
16
and
17
indicate O-rings. Numeral
18
indicates a cylindrical holder provided in the rotor
7
. An engagement hole
18
a
, for engaging a plunger described later therewith is provided in the holder
18
to extend in an axial direction.
Numeral
19
indicates a plunger slidably provided in the housing
5
and provided with an engagement shaft portion
19
a
fitted within the hole
18
a
of the holder
18
. Numeral
20
indicates a spring for urging the plunger
19
toward the holder
18
. Numeral
21
indicates a plunger oil passage for introducing the hydraulic oil into the engagement hole
18
a
of the holder
18
. The hydraulic oil introduced into the engagement hole
18
a
of the holder
18
via the plunger oil passage
21
displaces the plunger
19
against the urging force of the spring
20
so that the holder
18
is released from the locking action provided by the plunger
19
. Numeral
22
indicates an air vent. Numeral
22
indicates an air vent. Numeral
23
indicates a shaft bolt for securing the rotor
7
to the cam shaft
1
. Numeral
24
indicates an air vent.
Numeral
25
indicates a first oil passage provided in the cam shaft
1
and the rotor
7
to communicate with a lag oil hydraulic chamber (not shown) for displacing the rotor
7
in a lagging direction. Numeral
26
indicates a second oil passage provided in the cam shaft
11
and the rotor
7
to communicate with an advance oil hydraulic chamber (not shown) for displacing the rotor
7
in an advancing direction.
Numeral
27
indicates a oil control valve (hereinafter, referred to as OCV) for supplying hydraulic oil to the actuator
3
and controlling the quantity of the oil supplied. Numeral
28
indicates a substantially cylindrical valve housing having a port corresponding to an open end of pipelines
32
-
35
described later. Numeral
29
indicates a spool that slides in the valve housing
28
in an axial direction of the valve housing
28
. Numeral
30
indicates a spring that urges the spool in one direction. Numeral
31
indicates a linear solenoid for actuating the spool
29
against the urging force of the spring
30
. Numeral
32
indicates a supply pipeline for guiding the hydraulic oil supplied via an oil pump described later to the valve housing
28
. Numeral
33
indicates a drain pipeline for returning the hydraulic oil inside the valve housing
28
to an oil pan described later. Numeral
34
indicates a first pipeline for guiding the hydraulic oil to the first oil passage
25
. Numeral
35
indicates a second pipeline for guiding the hydraulic oil to the second oil passage
26
. Numeral
36
indicates an oil pan. Numeral
37
indicates an oil pump. Numeral
38
indicates an oil filter for eliminating impurities from the hydraulic oil. The oil pan
36
, the oil pump
37
and the oil filter
38
constitute a lubricating system for lubricating various parts o the engine (not shown). The oil pan
36
, the oil pump
37
, the oil filter
38
and the OCV
27
constitute a system for supplying the hydraulic oil to the actuator
3
.
Numeral
39
indicates an engine block provided with a recess for accommodating the valve housing
28
. The interior of the recess of the engine block
39
houses the pipelines
32
-
35
so as to allow open ends of the pipelines
32
-
35
to face respective ports of the valve housing
28
.
Numeral
40
indicates an electronic control unit (ECU). The ECU controls fuel injection quantity, ignition timing and valve opening/closing timing by actuating an injector, ignitor and the OCV
27
based on signals from an intake air quantity sensor (not shown), a throttle sensor (not shown), a water temperature sensor (not shown), a crank angle sensor (not shown) and a cam angle sensor (not shown). The ECU also controls the OCV
27
closing timing subsequent to turning off of the ignition switch.
A description will now be given of the operation of the actuator
3
and the OCV
27
.
When the engine is at a stop, the rotor
7
is at a position with a maximum lagging displacement. That is, the rotor
7
is rotated by a maximum advance angle with respect to the housing
5
. The oil pump
37
is not in operation so that the hydraulic oil is not supplied to the first oil passage
25
, the second oil passage
26
and the plunger oil passage
21
. The pressure of the oil retained inside the actuator
3
is relatively low. Therefore, the plunger
19
is thrust against the holder
18
by the urging force of the spring
20
. The engagement shaft portion
19
a
of the plunger
19
is engaged with the engagement hole
18
a
of the holder
18
so that the housing
5
and the rotor
7
remains locked to each other.
When the engine is started in this locked state, the oil pump
37
is put into operation so that the pressure of the hydraulic oil supplied to the OCV
27
is increased. The hydraulic oil is supplied by the OCV
27
to the lag oil hydraulic chamber (not shown) in the actuator
3
via the first pipeline
34
and the first oil passage
25
. Due to the pressure built up in the lag oil hydraulic chamber, a slide plate (not shown) is displaced toward the advance oil hydraulic chamber (not shown) so that the lag oil hydraulic chamber and the plunger oil passage
21
communicate with each other. The hydraulic oil is supplied from the plunger
21
to the engagement hole
18
a
of the holder
18
and the plunger
19
is then thrust against the urging force of the spring
20
. As a result of this, the engagement shaft portion
19
a
of the plunger
19
is pulled out of the engagement hole
18
a
of the holder
18
so that the plunger
19
and the rotor
7
become disengaged.
Subsequently, the hydraulic oil is supplied by the OCV
27
to the advance oil hydraulic chamber (not shown) via the second pipeline
35
and the second oil passage
26
so as to advance the rotor
7
. The oil pressure is transmitted to the plunger oil passage
21
SO as to displace the plunger
19
toward the housing
5
against the urging force of the spr

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