Internal-combustion engines – Poppet valve operating mechanism – Electrical system
Reexamination Certificate
1999-08-05
2001-01-23
Walberg, Teresa (Department: 3742)
Internal-combustion engines
Poppet valve operating mechanism
Electrical system
Reexamination Certificate
active
06176209
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system and method for controlling electromagnetically operated intake and exhaust valves of an internal combustion engine.
2. Prior Arts
An elctromagnetically operated valve mechanism is of a valve driving technique in which a valve body is operated by generating magnetic force in an actuator by supplying current thereto and there are numerous proposed techniques relating to that mechanism. The electromagnetically operated valve mechanism is characterized in that the construction of the valve driving mechanism can be simplified because of the absence of a cam mechanism and further the valve opening and closure timing of the intake and exhaust valves can be selectively established according to engine operating conditions, this enabling a wide range of selection of engine output characteristics and further leading to an improvement of fuel economy.
FIG. 14
is a schematic cross sectional view showing an example of an electromagnetically operated valve mechanism according to the prior art. The shown electromagnetically operated valve mechanism is an example employed on the exhaust valve side. With respect to the intake valve side, its detailed description will be omitted because of a similar construction. As shown, generally, the electromagnetically operated valve mechanism
110
comprises a valve body
120
, an electromagnetic force generating section
130
, a biasing section
140
and an armature
150
. Also the valve body
120
comprises a valve
121
and a valve stem
122
and it is reciprocatably supported by a stem guide
161
provided in a cylinder head
160
.
The valve
121
is formed so as to have a close contact with a valve seat
164
provided around an exhaust port end
163
. Further, the valve stem
122
is connected at the top end thereof with the armature
150
fabricated of magnetic material.
The electromagnetic force generating section
130
is constituted by an electromagnetic solenoid
131
for closing a valve (hereinafter, referred to as valve closing solenoid, an electromagnetic solenoid
132
for opening a valve (hereinafter, referred to as valve opening solenoid), a first core
133
for the valve closing solenoid
131
and a second core
134
for the valve opening solenoid
132
. The armature
150
is inserted between the first and second cores
133
,
134
so as to move vertically therebetween.
The biasing section
140
comprises a spring
141
for opening a valve (hereinafter, referred to as valve opening spring) and a spring
142
for closing a valve (hereinafter, referred to as valve closing spring). The valve opening spring
141
is provided between the first core
133
and the valve stem
122
so as to bias the valve body
120
in the opening direction (downward direction in this drawing) with a specified biasing force. Further, the valve closing spring
142
is provided between the second core
134
and the armature
150
so as to bias the valve body
120
in the closing direction (upward direction in this drawing) with a specified biasing force.
When the valve closing solenoid
131
and the valve opening solenoid
132
are both deenergized, the valve opening spring
141
and the valve closing spring
142
have such a biasing force respectively that the armature
150
is sustained at about the mid-point between the first and second cores
133
,
134
. Therefore, when either of these solenoids
131
,
132
is energized, the armature
150
can be attracted with less attraction force.
Describing an operation of this valve mechanism briefly, first, when the valve closing solenoid
131
is energized, an electromagnetic force is generated in the valve closing solenoid
131
to attract the armature
150
in the direction of the valve closing solenoid
131
against the biasing force of the valve opening spring
141
and as a result the valve body
120
travels in the closing direction (upward direction in this drawing) until the valve
121
comes into close contact with the valve seat
164
. Thus, the combustion chamber
165
is sealed up against the exhaust port
162
.
When the valve opening solenoid
132
is energized, the armature
150
is attracted toward the valve opening solenoid
132
to move the valve body
120
in the opening direction (downward direction) until the valve
121
is fully open.
FIG. 14
shows a state in which the electromagnetic force generating section
130
is deenergized and the armature
150
is positioned at the mid-point of the first core
133
and the second core
134
.
Japanese Patent Application Laid-open No. Toku-Kai-Shou 61-76713 discloses an electromagnetically operated valve control system in which the valve speed immediately before seating on the valve seat is reduced to alleviate an impact when seated. Further, Japanese Patent Application Laid-open No. Toku-Kai-Hei 7-224624 discloses an electromagnetically operated valve train apparatus wherein the lift amount is detected by a lift sensor.
In applying the foregoing electromagnetically operated valve train system to a multi-cylinders engine, the current control must be performed per respective electromagnetic solenoids provided on each cylinder. In case of an electromagnetically operated valve train system as shown in
FIG. 14
, two electromagnetic solenoids, one for opening the valve and the other for closing the valve, are employed. Therefore, for example, in case of a four cylinders-four valves engine, thirty-two (32) electromagnetic solenoids must be controlled independently.
In order to generate signals for driving these numerous electromagnetic solenoids in the micro-computer in a timely manner, it is necessary to increase the number of channels and to enlarge the computing capacity of the micro-computer. Further, when performing such a fine valve opening and closing control as proposed in Toku-Kai-Shou 61-76713 or Toku-Kai-Hei 7-224624, still greater burden is charged on the micro-computer.
Therefore, in order to perform the above-mentioned valve opening and closing control, a high performance computer must be used, this resulting in a cost increase of the system.
SUMMARY OF THE INVENTION
With the above described problem in mind, it is an object of the present invention to provide an electromagnetically operated valve control system capable of performing a more precise and more sophisticated valve driving control with less burden on the micro-computer.
In order to achieve the above-mentioned object, the electromagnetically operated valve control system comprises: control data generating means for generating a control data based on operating conditions of the engine, valve position detecting means for detecting reference positions of the valve body, valve closing acceleration means for energizing a valve closing solenoid when the valve body passes a first reference position apart from the fully open position and for deenergizing a valve closing solenoid when the valve body passes a second reference position closer to the fully closed position than the first reference position, valve seating velocity adjusting means for energizing the valve closing solenoid when the valve body passes a third reference position closer to the fully closed position than the second reference position and for deenergizing the valve closing solenoid when the valve body passes a fourth reference position closer to the fully closed position than the third reference position so as to adjust a seating velocity of the valve body, valve closing hold means for repeatedly energizing and deenergizing the valve closing solenoid when the valve body passes the fourth reference position and for deenergizing the valve closing solenoid when a first specified period has elapsed since the valve body passes the fourth reference position, valve opening acceleration means for energizing the valve opening solenoid when the valve body passes a fifth reference position apart from the fully closed position and for deenergizing the valve opening solenoid when the valve body passes a sixth reference position closer to the ful
Farber Martin A.
Fuji Jukogyo Kabushiki Kaisha
Patel Vinod D.
Walberg Teresa
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