Valve timing control system for internal combustion engine

Details Valve timing control system for internal combustion engine Valve timing control system for internal combustion engine

1999-11-17

2001-01-09

Lo, Weilun (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

With means for varying timing

C123S090170

Reexamination Certificate

active

06170446

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to valve timing control for an internal combustion engine, which is made to learn a maximum retardation position in the valve timing.
2. Description of the Related Art
Conventionally, an apparatus is known which variably controls the valve timing of at least the intake valves or the exhaust valves according to engine operating conditions.
In addition, a system for controlling such an apparatus is well known, as disclosed in Japanese Patent Application Laid-open No. 9-345264. Referring to
FIGS. 11
to
19
, a description will be made hereinbelow of a conventional valve timing control system for an internal combustion engine.
FIG. 11
schematically shows the configuration of an internal combustion gasoline engine system having a common variable valve timing actuator.
In
FIG. 11
, an internal combustion engine
1
is composed of a plurality of (for example, four) cylinders which constitute a main body thereof. In this illustration, only one cylinder of the internal combustion engine
1
is shown.
A cylinder block
2
forms a cylinder portion of the internal combustion engine
1
. A cylinder head
3
is connected to a top portion of the cylinder block
2
.
A piston
4
is accommodated in each of the cylinders in the cylinder block
2
, and is made to reciprocate up and down. A crank shaft
5
, being connected to a lower end portion of the piston
4
, is driven to rotate in accordance with the vertical movements of the piston
4
.
A crank angle sensor
6
is made up of an electromagnetic pickup installed in the vicinity of the crank shaft
5
, and outputs a crank angle signal SGT in synchronism with the rotation of the crank shaft
5
of the internal combustion engine
1
. The crank angle signal SGT is used for detecting the speed Ne of the internal combustion engine
1
and further for detecting if the crank shaft
5
is at a predetermined reference crank angle (degCA).
A signal rotor
7
is connected integrally with the crank shaft
5
, and has, at its outer circumference, two teeth
7
a
made of a magnetic substance and arranged at an interval of 180° rotation angle. The crank angle sensor
6
generates a pulse-like crank angle signal SGT whenever either of the teeth
7
a
passes in front of the crank angle sensor
6
.
A combustion chamber
8
is defined by an inner wall of the cylinder block
2
, an inner wall of the cylinder head
3
and the top of the piston
4
, and an air-fuel mixture introduced into the internal combustion engine
1
is combusted therein. An ignition plug
9
is installed in the top portion of the cylinder head
3
such that it protrudes into the interior of the combustion chamber
8
, and ignites the air-fuel mixture by discharging.
A distributor
10
is connected to an exhaust side cam shaft
20
(which will be described herein later) in the cylinder head
3
, and successively applies a high voltage for ignition to the ignition plug
9
of each of the cylinders. An igniter
11
generates the high ignition voltage.
Each of the ignition plugs
9
is coupled through a high-tension cord (not shown) to the distributor
10
, and the high voltage output from the igniter
11
is distributed through the distributor
10
to each of the ignition plugs
9
in synchronism with the rotation of the crank shaft
5
.
A water temperature sensor
12
is located in the cylinder block
2
to sense the temperature W of a coolant (coolant temperature) flowing in a coolant passage. An intake port
13
is provided on the intake side of the cylinder head
3
, while an exhaust port
14
is provided on the exhaust side of the cylinder head
3
.
An intake passage
15
communicates with the intake port
13
, while an exhaust passage
16
communicates with the exhaust port
14
. An intake valve
17
is placed in the intake port
13
of the cylinder head
3
, while an exhaust valve
18
is placed in the exhaust port
14
of the cylinder head
3
.
An intake side cam shaft
19
is situated above the intake valve
17
to open and close the intake valve
17
, while an exhaust side cam shaft
20
is situated above the exhaust valve
18
to open and close the exhaust valve
18
.
An intake side timing pulley
21
is mounted on one end portion of the intake side cam shaft
19
, while an exhaust side timing pulley
22
is mounted on one end portion of the exhaust side cam shaft
20
. A timing belt
23
makes a connection of the timing pulleys
21
,
22
to the crank shaft
5
. Each of the cam shafts
19
,
20
is made to rotate at a speed being ½ of that of the crank shaft
5
.
In an operation of the internal combustion engine
1
, the rotational drive force of the crank shaft
5
is transmitted through the timing belt
23
and the timing pulleys
21
,
22
to the cam shafts
19
,
20
so that the cam shafts
19
,
20
rotate.
Thus, the intake valve
17
and the exhaust valve
18
are driven to open and close in synchronism with the rotation of the crank shaft
5
and the vertical movements of the piston
4
.
That is, the valves
17
and
18
are driven at predetermined opening and closing timings in synchronism with a series of four strokes: an intake stroke, a compression stroke, an explosion (expansion) stroke and an exhaust stroke, in the internal combustion engine
1
.
A cam angle sensor
24
is installed in the vicinity of the intake side cam shaft
19
, and outputs a cam angle signal SGC for detecting an operating timing (valve timing) of the intake valve
17
.
A signal rotor
25
is integrally connected to the intake side cam shaft
19
, and has, at its outer circumference, four teeth
25
a
made of a magnetic substance arranged at intervals of a 90° rotational angle. The cam angle sensor
24
outputs a pulsed cam angle signal SGC whenever any of the teeth
25
a
passes in front of the cam angle sensor
24
.
A throttle valve
26
is installed in the middle of the intake passage
15
and is operated by the accelerator pedal (not shown) to open and close, thereby adjusting the air flow rate into the internal combustion engine
1
, that is, an intake air amount Q.
A throttle sensor
27
is connected to the throttle valve
26
to sense the throttle opening degree &thgr;.
An intake air amount sensor
28
is placed on the upstream side of the throttle valve
26
to detect the intake air amount Q flowing in the intake passage
15
according to, for example, a thermal method.
A surge tank
29
is formed on the downstream side of the throttle valve
26
to suppress the intake pulsation.
Each of injectors
30
is individually placed in the vicinity of the intake port
13
of each of the cylinders to inject fuel so that an air-fuel mixture is supplied into the interior of the combustion chamber
8
. Each of the injectors
30
is composed of a solenoid valve which assumes an open condition in response to energization. The injector
30
receives the supply of fuel sent under pressure from a fuel pump (not shown).
In the operation of the internal combustion engine
1
, simultaneous with the introduction of air into the intake passage
15
, each of the injectors
30
injects fuel into the intake port
13
.
As a result of this, an air-fuel mixture is produced in the intake port
13
, and is introduced upon the opening of the intake valve
17
into the combustion chamber
8
during the intake stroke.
A variable valve timing actuator (which will be referred to hereinafter as a VVT actuator)
40
is connected to the intake side cam shaft
19
, and is driven by an operating oil (lubricating oil) to change the valve timing (i.e., opening and closing) of the intake valve
17
and/or the exhaust valve
18
.
The VVT actuator
40
changes the displacement angle of the intake side cam shaft
19
with respect to the intake side timing pulley
21
, thereby changing the valve timing of the intake valve
17
.
An oil control valve (which will be referred to hereinafter as an OCV)
80
supplies the operating oil to the VVT actuator
40
, and also adjusts the amount of the operating oil supplied thereto.
An electronic control

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