Information
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Patent Grant
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6276318
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Patent Number
6,276,318
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Date Filed
Wednesday, June 7, 200024 years ago
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Date Issued
Tuesday, August 21, 200123 years ago
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Inventors
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Original Assignees
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Examiners
Agents
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CPC
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US Classifications
Field of Search
US
- 123 9011
- 251 12901
- 251 1291
- 251 12915
- 251 12916
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International Classifications
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Abstract
A solenoid valve actuating apparatus wherein an actuating circuit for controlling exciting currents to electromagnets for actuating a plurality of engine valves so that the engine valves will be opened and closed can be formed by a small number of switching means is provided. Two of the engine valves form one engine valve group, and the actuating circuit is provided for each of the engine valve groups. The actuating circuit includes three series circuits each having three switching means connected in series between a first line terminal on a high voltage side and a second line terminal on a low voltage side. Four of the electromagnets each corresponding to each of the engine valve groups connect connecting-in-series portions between the switching means between different series circuits.
Description
TECHNICAL FIELD
The present invention relates to a solenoid valve actuating apparatus, and more particularly, to a solenoid valve actuating apparatus suitable for actuating a plurality of valves operating in synchronism with each other such as, for example, a plurality of intake valves or exhaust valves provided for each cylinder of an internal combustion engine, or the like.
BACKGROUND ART
Conventionally, for example as disclosed in Japanese Laid-Open Patent Application 8-284626, a solenoid valve for use as an intake or exhaust valve of an internal combustion engine is known. This solenoid valve is provided with an armature moving with an engine valve as a unity, a pair of solenoid coils disposed above and below the armature, and springs pushing the engine valve toward a neutral position.
When neither of the solenoid coils is supplied with an exciting current, the engine valve and the armature are held in the neutral position. Further, when an upper solenoid coil is supplied with the exciting current, the engine valve and the armature are attracted to the upper solenoid coil, while the engine valve and the armature are attracted to a lower solenoid coil when the lower solenoid coil is supplied with the exciting current. Therefore, according to the above described conventional solenoid valve, the engine valve can be operated so as to be opened and closed by alternately supplying the solenoid coils with proper exciting currents. In this case, ends of movement on closing and opening sides of the engine valve are controlled by the adhesion of the armature to the solenoid coils. Therefore, if electromagnetic forces generated by the solenoid coils can be made to promptly vanish in positions near the ends of movement of the engine valve, an excellent operational responsiveness of the solenoid valve can be realized, and the control of an impact sound and the improvement in durability are made possible because impact forces exerted between the armature and the solenoid coils are reduced.
For this purpose, the exciting currents supplied to the solenoid coils are controlled by a bridged-H-type circuit in the above described conventional solenoid valve. This bridged-H-type circuit includes a total of four switching means disposed respectively between terminals of the solenoid coil, and cathode and anode sides of a power supply. According to the bridged-H circuit, the solenoid coil can be energized in a predetermined direction by setting one pair of the switching means which are disposed diagonally across the solenoid coil to an ON state and the other pair to an OFF state. Further, the solenoid coil can be energized in the reverse direction by reversing the above described ON and OFF states. Therefore, the electromagnetic force generated by the solenoid coil can be made to promptly vanish by energizing the solenoid coil in the reverse direction to the exciting current by switching the ON and OFF states of the switching means of the bridged-H-type circuit when the engine valve approaches the end of movement.
However, as described above, the above described conventional solenoid valve requires four switching means for each of the solenoid coils. That is, eight switching means will be required for one solenoid valve as one solenoid valve is provided with two solenoid coils. Therefore, when the above described conventional solenoid valve is applied to an engine of a four-cylinder-four-valve type, for example, one hundred and twenty-eight switching means will be required, thus causing the cost of an actuating apparatus for actuating the solenoid valves to rise.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to reduce a number of switching means required to control an exciting current to a solenoid coil to actuate an engine valve.
The above object is achieved by a solenoid valve actuating apparatus for actuating a plurality of engine valves, for each of which provided are a first electromagnet to actuate the engine valve in a first predetermined direction and a second electromagnet to actuate the engine valve in a second predetermined direction, by means of the first and the second electromagnets so that a plurality of the engine valves will be opened and closed, the solenoid valve actuating apparatus wherein:
two of the engine valves form one engine valve group and an actuating circuit is provided for each of the engine valve groups;
the actuating circuit includes three series circuits each having three switching means connected in series between a first line terminal on a high voltage side and a second line terminal on a low voltage side; and
four of the electromagnets corresponding to each of the engine valve groups connect connecting-in-series portions between the switching means between different series circuits.
In the present invention, each of the engine valves is actuated by the first and the second electromagnets in the first and the second predetermined directions, respectively. Two of the engine valves form one engine valve group and the actuating circuit is provided for each of the engine valve groups. The actuating circuit includes the three series circuits each having the three switching means connected in series. Therefore, the exciting currents to the four electromagnets corresponding to the two engine valves can be controlled by nine of the switching means. The four electromagnets are connected between the different series circuits. Therefore, each of the electromagnets can be supplied with the exciting currents in both directions by the combinations of ON and OFF states of the switching means of each of the series circuits, and electromagnetic forces exerted on the engine valve can be made to promptly vanish by enabling currents flowing through the electromagnets to flow into the first line terminal.
In this case, the actuating circuit may include a first through third series circuits having a first through third switching means connected in series in order from the first line terminal side between the first line terminal and the second line terminal, and the four electromagnets may be connected between a connecting portion of the first and the second switching means of the first series circuit and a connecting portion of the first and the second switching means of the second series circuit, between a connecting portion of the second and the third switching means of the first series circuit and a connecting portion of the second and the third switching means of the second series circuit, between the connecting portion of the first and the second switching means of the second series circuit and a connecting portion of the first and the second switching means of the third series circuit, and between the connecting portion of the second and the third switching means of the second series circuit and a connecting portion of the second and the third switching means of the third series circuit, respectively.
In the present invention, the actuating circuit includes the first through third series circuits wherein the first through third switching means are connected in series between the first line terminal and the second line terminal. The four electromagnets are connected between the series circuits. For example, a state wherein the exciting current is supplied from the second series circuit side in a direction toward the first series circuit side (hereinafter referred to as a first direction) is formed of the electromagnet connected between the connecting portion of the first and the second switching means of the first series circuit and the connecting portion of the first and the second switching means of the second series circuit by setting to the ON state the first switching means of the second series circuit, and the second and the third switching means of the first series circuit. Further, a state wherein the exciting current flowing in the first direction flows into the first line terminal or the exciting current is supplied in the reverse direction to the first direction is formed by setting to the ON state the first switching means of the first series circuit, and the second and the third switching means of the second series circuit. The same states are formed of the other electromagnets by the combinations of the ON and the OFF states of the switching means.
Further, the first electromagnet corresponding to one engine valve of each of the engine valve groups may be connected between the connecting portion of the first and the second switching means of the first series circuit and the connecting portion of the first and the second switching means of the second series circuit, the second electromagnet corresponding to the one engine valve may be connected between the connecting portion of the second and the third switching means of the first series circuit and the connecting portion of the second and the third switching means of the second series circuit, the first electromagnet corresponding to another engine valve may be connected between the connecting portion of the second and the third switching means of the second series circuit and the connecting portion of the second and the third switching means of the third series circuit, and the second electromagnet corresponding to the other engine valve may be connected between the connecting portion of the first and the second switching means of the second series circuit and the connecting portion of the first and the second switching means of the third series circuit.
In the present invention, the first electromagnet corresponding to the one engine valve of each of the engine valve groups (hereinafter referred to as a first engine valve) is connected between the connecting portion of the first and the second switching means of the first series circuit and the connecting portion of the first and the second switching means of the second series circuit. Further, the second electromagnet corresponding to the first engine valve is connected between the connecting portion of the second and the third switching means of the first series circuit and the connecting portion of the second and the third switching means of the second series circuit. On the other hand, the first electromagnet corresponding to the other engine valve (hereinafter referred to as a second engine valve) is connected between the connecting portion of the second and the third switching means of the second series circuit and the connecting portion of the second and the third switching means of the third series circuit. Further, the second electromagnet corresponding to the second engine valve is connected between the connecting portion of the first and the second switching means of the second series circuit and the connecting portion of the first and the second switching means of the third series circuit.
When the first and the second switching means of the first series circuit, the first and the third switching means of the second series circuit, and the second and the third switching means of the third series circuit are set to the ON state, a state wherein the second electromagnet of the first engine valve is supplied with the exciting current from the first series circuit side in a direction toward the second series circuit side, and the second electromagnet of the second engine valve is supplied with the exciting current from the second series circuit side in a direction toward the third series circuit side is formed. Further, when the second and the third switching means of the first series circuit, the first and the third switching means of the second series circuit, and the first and the second switching means of the third series circuit are set to the ON state, a state wherein the first electromagnet of the first engine valve is supplied with the exciting current from the second series circuit side in a direction toward the first series circuit side, and the first electromagnet of the second engine valve is supplied with the exciting current from the third series circuit side in the direction toward the second series circuit side is formed. Hereinafter, a direction of the exciting currents supplied to the electromagnets in these two states are referred to as a positive direction and a direction reverse to this is referred to as a reverse direction. Further, a state wherein an electromagnet is supplied with an exciting current in the positive direction is referred to as a powered state.
On the other hand, when the third switching means of the first series circuit, the second switching means of the second series circuit and the first switching means of the third series circuit are set to the ON state, a state wherein the exciting currents in the positive direction flowing through the second electromagnet of the first engine valve and the second electromagnet of the second engine valve flow into the first line terminal side, or these two electromagnets are supplied with the exciting currents in the reverse direction is formed. Hereinafter, a state wherein an exciting current in the positive direction flowing through an electromagnet flows into the first line terminal side or the electromagnet is supplied with the exciting current in the reverse direction is referred to as a regenerative/reverse current state of the electromagnet. Further, when the first switching means of the first series circuit, the second switching means of the second series circuit and the third switching means of the third series circuit are set to the ON state, a state wherein the first electromagnet of the first engine valve and the first electromagnet of the second engine valve are set to the regenerative/reverse current state is formed.
When the first and the second switching means of the first series circuit and the third switching means of the second series circuit are set to the ON state, a state wherein the second electromagnet of the first engine valve is set to the powered state is formed. Further, when the first switching means of the second series circuit and the second and the third switching means of the third series circuit are set to the ON state, a state wherein the second electromagnet of the second engine valve is set to the powered state is formed.
When the third switching means of the second series circuit and the first and the second switching means of the third series circuit are set to the ON state, a state wherein the first electromagnet of the second engine valve is set to the powered state is formed. Further, when the second and the third switching means of the first series circuit and the first switching means of the second series circuit are set to the ON state, a state wherein the first electromagnet of the first engine valve is set to the powered state is formed.
When the third switching means of the first series circuit and the first and the second switching means of the second series circuit are set to the ON state, a state wherein the second electromagnet of the first engine valve is set to the regenerative/reverse current state is formed. Further, when the second and the third switching means of the second series circuit and the first switching means of the third series circuit are set to the ON state, a state wherein the second electromagnet of the second engine valve is set to the regenerative/reverse current state is formed.
When the second and the third switching means of the first series circuit, the first switching means of the second series circuit and the second and the third switching means of the third series circuit are set to the ON state, a state wherein the first electromagnet of the first engine valve and the second electromagnet of the second engine valve are set to the powered state is formed. Further, when the first and the second switching means of the first series circuit, the third switching means of the second series circuit and the first and the second switching means of the third series circuit are set to the ON state, a state wherein the first electromagnet of the second engine valve and the second electromagnet of the first engine valve are set to the powered state is formed.
When the first switching means of the first series circuit and the second and the third switching means of the second series circuit are set to the ON state, a state wherein the first electromagnet of the first engine valve is set to the regenerative/reverse current state is formed. Further, when the first and the second switching means of the second series circuit and the third switching means of the third series circuit are set to the ON state, a state wherein the first electromagnet of the second engine valve is set to the regenerative/reverse current state is formed.
Thus, according to the present invention, by means of the nine switching means, the first or the second electromagnet of both or one of the first and the second engine valves can be set to the powered state or to the regenerative/reverse current state depending on the combinations of the ON and the OFF states of each of the nine switching means. In the regenerative/reverse current state, the electromagnetic forces generated by the electromagnets are made to promptly vanish because the exciting currents flowing through the electromagnets are promptly reduced, and further, the exciting currents are supplied in the reverse direction. Therefore, by properly realizing the powered state and the regenerative/reverse current state of each of the electromagnets in accordance with the operation of the engine valve, the electromagnetic forces exerted on the engine valve can be made to promptly vanish at a required timing after the engine valve is actuated.
The above object is further achieved by a solenoid valve actuating apparatus for actuating a plurality of engine valves, for each of which provided are a first electromagnet to actuate the engine valve in a first predetermined direction and a second electromagnet to actuate the engine valve in a second predetermined direction, by means of the first and the second electromagnets so that a plurality of the engine valves will be opened and closed, the solenoid valve actuating apparatus wherein:
two of the engine valves form one engine valve group and an actuating circuit is provided for each of the engine valve groups;
the actuating circuit includes:
a first and a second series circuits each having three switching means connected in series between a first line terminal on a high voltage side and a second line terminal on a low voltage side; and
a third series circuit wherein two of the switching means and one diode disposed so as to allow a current flow from the second line terminal side to the first terminal side are connected in series between the first line terminal and the second line terminal so that the diode will be disposed in a center; and
four of the electromagnets corresponding to each of the engine valve groups are connected between connecting portions of the switching means and the diode of the third series circuit and connecting portions between the switching means of the first or the second series circuit.
In the present invention, two of the engine valves belonging to each of the engine valve groups are actuated by a total of four of the electromagnets. The actuating circuit is provided with the first and the second series circuits having the three switching means connected in series, and with the third series circuit having the diode to allow a current to flow from the low voltage side to the high voltage side connected in series between the two switching means. Therefore, the exciting currents to the four electromagnets can be controlled by the eight switching means and the one diode. Each of the four electromagnets is connected between the third series circuit and the first or the second series circuit. Therefore, the electromagnets can be supplied with the exciting currents in a predetermined direction by the combinations of the ON and the OFF states of the switching means of the series circuits, and the electromagnetic forces exerted on the engine valve can be made to promptly vanish by having the exciting currents flowing through the electromagnets flow into the first line terminal side.
In this case, the actuating circuit may include the first and the second series circuits each having a first through third switching means connected in series in order from the first line terminal side between the first line terminal and the second line terminal, and the third series circuit having a first switching means, the diode provided so as to allow the current flow from the second line terminal side to the first terminal side and a second switching means connected in series in order from the first line terminal side between the first line terminal and the second line terminal, and the four electromagnets may be connected between a connecting portion of the first and the second switching means of the first series circuit and a connecting portion of the first switching means and the diode of the third series circuit, between a connecting portion of the second and the third switching means of the first series circuit and a connecting portion of the diode and the second switching means of the third series circuit, between a connecting portion of the first and the second switching means of the second series circuit and the connecting portion of the first switching means and the diode of the third series circuit, and between a connecting portion of the second and the third switching means of the second series circuit and the connecting portion of the diode and the second switching means of the third series circuit, respectively.
In the present invention, two of the engine valves belonging to each of the engine valve groups are actuated by a total of four of the electromagnets. The actuating circuit is provided with the first and the second series circuits having the first through third switching means connected in series between the first line terminal and the second line terminal, and with the third series circuit having the first switching means, the diode provided so as to allow the current flow from the second line terminal side to the first terminal side and a second switching means connected in series from the first line terminal side to the second line terminal side. That is, eight of the switching means and the one diode are provided for the four electromagnets. The four electromagnets are connected between the first or the second series circuit and the third series circuit. For example, a state wherein the exciting current is supplied in the first direction from the third series circuit side to the first series circuit side is formed of the electromagnet connected between the connecting portion of the first and the second switching means of the first series circuit and the connecting portion of the first switching means and the diode of the third series circuit by setting to the ON state the first switching means of the third series circuit, and the second and the third switching means of the first series circuit. Further, a state wherein the exciting current flowing in the first direction flows into the first line terminal is formed by setting to the ON state the first switching means of the first series circuit and the second switching means of the third series circuit. The same states are formed of the other electromagnets by the combinations of the ON and the OFF states of the switching means.
Further, the first electromagnet corresponding to one engine valve of each of the engine valve groups may be connected between the connecting portion of the first and the second switching means of the first series circuit and the connecting portion of the first switching means and the diode of the third series circuit, the second electromagnet corresponding to the one engine valve may be connected between the connecting portion of the second and the third switching means of the first series circuit and the connecting portion of the second switching means and the diode of the third series circuit, the first electromagnet corresponding to another engine valve may be connected between the connecting portion of the second and the third switching means of the second series circuit and the connecting portion of the second switching means and the diode of the third series circuit, and the second electromagnet corresponding to the other engine valve may be connected between the connecting portion of the first and the second switching means of the second series circuit and the connecting portion of the first switching means and the diode of the third series circuit.
In the present invention, the first electromagnet corresponding to the one engine valve of each of the engine valve groups (hereinafter referred to as a first engine valve) is connected between the connecting portion of the first and the second switching means of the first series circuit and the connecting portion of the first switching means and the diode of the third series circuit. Further, the second electromagnet corresponding to the one engine valve is connected between the connecting portion of the second and the third switching means of the first series circuit and the connecting portion of the second switching means and the diode of the third series circuit. The first electromagnet corresponding to the other engine valve (hereinafter referred to as a second engine valve) is connected between the connecting portion of the second and the third switching means of the second series circuit and the connecting portion of the second switching means and the diode of the third series circuit. Further, the second electromagnet corresponding to the other engine valve is connected between the connecting portion of the first and the second switching means of the second series circuit and the connecting portion of the first switching means and the diode of the third series circuit.
When the first and the second switching means of the first series circuit, the second and the third switching means of the second series circuit and the first and the second switching means of the third series circuit are set to the ON state, a state wherein the second electromagnet of the first engine valve is supplied with the exciting current from the first series circuit side in a direction toward the third series circuit side, and the second electromagnet of the second engine valve is supplied with the exciting current from the third series circuit side in a direction toward the second series circuit side is formed. Further, when the second and the third switching means of the first series circuit, the first and the second switching means of the second series circuit, and the first and the second switching means of the third series circuit are set to the ON state, a state wherein the first electromagnet of the first engine valve is supplied with the exciting current from the third series circuit side in a direction toward the first series circuit side and the first electromagnet of the second engine valve is supplied with the exciting current from the second series circuit side in the direction toward the third series circuit side is formed. Hereinafter, a direction of the exciting currents supplied to the electromagnets in these two states are referred to as a positive direction, and a direction reverse to this is referred to as a reverse direction. Further, a state wherein an electromagnet is supplied with an exciting current in the positive direction is referred to as a powered state.
On the other hand, when the third switching means of the first series circuit and the first switching means of the second series circuit are set to the ON state, a state wherein the exciting currents in the positive direction flowing through the second electromagnet of the first engine valve and the second electromagnet of the second engine valve flow into the first line terminal side is formed. Hereinafter, a state wherein an exciting current in the positive direction flowing through an electromagnet flows into the first line terminal side is referred to as a regenerative state of the electromagnet. Further, when the first switching means of the first series circuit and the third switching means of the second series circuit are set to the ON state, a state wherein the first electromagnet of the first engine valve and the first electromagnet of the second engine valve are set to the regenerative state is formed.
When the first and the second switching means of the first series circuit and the second switching means of the third series circuit are set to the ON state, a state wherein the second electromagnet of the first engine valve is set to the powered state is formed. Further, when the second and the third switching means of the second series circuit and the first switching means of the third series circuit are set to the ON state, a state wherein the second electromagnet of the second engine valve is set to the powered state is formed.
When the first and the second switching means of the second series circuit and the second switching means of the third series circuit are set to the ON state, a state wherein the first electromagnet of the second engine valve is set to the powered state is formed. Further, when the second and the third switching means of the first series circuit and the first switching means of the third series circuit are set to the ON state, a state wherein the first electromagnet of the first engine valve is set to the powered state is formed.
When the third switching means of the first series circuit and the first switching means of the second series circuit are set to the ON state, a state wherein the second electromagnet of the first engine valve is set to the regenerative state is formed. Further, the first switching means of the second series circuit and the second switching means of the third series circuit are set to the ON state, a state wherein the second electromagnet of the second series circuit is set to the regenerative state is formed.
When the second and the third switching means of the first series circuit, the second and the third switching means of the second series circuit and the first switching means of the third series circuit are set to the ON state, a state wherein the first electromagnet of the first engine valve and the second electromagnet of the second engine valve are set to the powered state is formed. Further, when the first and the second switching means of the first series circuit, the first and the second switching means of the second series circuit and the second switching means of the third series circuit are set to the ON state, a state wherein the first electromagnet of the second engine valve and the second electromagnet of the first engine valve are set to the powered state is formed.
When the first switching means of the first series circuit and the second switching means of the third series circuit are set to the ON state, a state wherein the first electromagnet of the first engine valve is set to the regenerative state is formed. Further, when the third switching means of the second series circuit and the first switching means of the third series circuit are set to the ON state, a state wherein the first electromagnet of the second engine valve is set to the regenerative/reverse current state is formed.
Thus, according to the present invention, by means of the eight switching means and the one diode, the first or the second electromagnet of both or one of the first and the second engine valves can be set to the powered state or to the regenerative state depending on the combinations of the ON and the OFF states of the switching means. In the regenerative state, the electromagnetic forces generated by the electromagnets are made to promptly vanish by the prompt reduction of the exciting currents flowing through the electromagnets. Therefore, by properly realizing the powered state and the regenerative state of each of the electromagnets in accordance with the operation of the engine valve, the electromagnetic forces exerted on the engine valve can be made to promptly vanish at a required timing after the engine valve is actuated.
Each of the switching means may include a switching element turning on and off and a diode disposed in parallel with the switching element so as to allow a current to flow from the second line terminal side to the first line terminal side.
In the present invention, each of the switching means includes the switching element turning on and off and the diode disposed in parallel with the switching element so as to allow the current to flow from the second line terminal side to the first line terminal side. Therefore, each of the switching means allows the current to flow from the second line terminal side to the first line terminal side even if each of the switching means is set to the OFF state. Thus, when an exciting current to an electromagnet is cut off, a flywheel current can flow through the electromagnet by setting the ON and the OFF states of the switching means so that a closed circuit including the diodes which the switching means have and the solenoid coils will be made.
Further, each of the electromagnets may be supplied with the exciting current having a predetermined wave form by switching the combinations of the ON and the OFF states of the switching means.
In the present invention, each of the electromagnets is supplied with the exciting current having the predetermined wave form by switching the combinations of the ON and the OFF states of the switching means. Therefore, according to the present invention, the wave forms of the exciting currents supplied to the electromagnets can be controlled while the number of the switching means are reduced.
In this case, the predetermined wave form may include a wave form portion of a positive current in a predetermined positive direction and a wave form portion of a reverse current in the reverse direction to the positive direction.
In the present invention, when the electromagnet is supplied with the exciting current in the positive direction, the engine valve is actuated by the electromagnet. On the other hand, when the electromagnet is supplied with the exciting current in the reverse direction after the engine valve is actuated, the electromagnetic force generated by the electromagnet is made to promptly vanish. Therefore, bacause the wave form of the exciting current supplied to the electromagnet includes the wave form portion of the positive current and the wave form portion of the reverse current, the electromagnetic force generated by the electromagnet can be made to promptly vanish at a required timing after the electromagnetic force actuates the engine valve.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a diagram of a system structure of a solenoid valve actuating apparatus according to an embodiment of the present invention;
FIG. 2
shows wave forms of exciting currents supplied to an upper coil and a lower coil when both of two solenoid valves are actuated so as to be opened and closed in the present embodiment, and operations of the solenoid valve corresponding to the wave forms;
FIG. 3
is a diagram of an internal structure of an ECU provided for a solenoid valve actuating apparatus of the present embodiment;
FIG. 4
is a diagram showing an operational state of an actuating circuit wherein both of a #1 upper coil and a #2 upper coil are set to a powered state;
FIG. 5
is a diagram showing an operational state of the actuating circuit wherein both of the #1 upper coil and the #2 upper coil are set to a flywheel state;
FIG. 6
is a diagram showing an operational state of the actuating circuit wherein both of the #1 upper coil and the #2 upper coil are set to the flywheel state;
FIG. 7
is a diagram showing an operational state of the actuating circuit wherein both of the #1 upper coil and the #2 upper coil are set to a regenerative/reverse current state;
FIG. 8
is a diagram showing wave forms of exciting currents supplied to the #1 upper coil, a #1 lower coil, the #2 upper coil and a #2 lower coil when a #1 solenoid valve is operated so as to be opened and closed and a #2 solenoid valve is maintained in a closed state in the present embodiment;
FIG. 9
is a diagram showing an operational state of the actuating circuit wherein the #1 upper coil is set to the powered state and the #2 upper coil is set to the flywheel state;
FIG. 10
is a diagram showing an operational state of the actuating circuit wherein the #1 upper coil is set to the flywheel state and the #2 upper coil is set to the powered state;
FIG. 11
is a diagram showing an operational state of the actuating circuit wherein the #1 upper coil is set to the regenerative/reverse current state and the #2 upper coil is set to the flywheel state;
FIG. 12
is a diagram showing an operational state of the actuating circuit wherein both of the #1 lower coil and the #2 upper coil are set to the powered state;
FIG. 13
is a diagram showing an operational state of the actuating circuit wherein the #1 lower coil is set to the powered state and the #2 upper coil is set to the flywheel state;
FIG. 14
is a diagram showing an operational state of the actuating circuit wherein the #1 lower coil is set to the flywheel state and the #2 upper coil is set to the powered state;
FIG. 15
is a diagram showing an operational state of the actuating circuit wherein both of the #1 lower coil and the #2 upper coil are set to the flywheel state;
FIG. 16
is a diagram showing an operational state of the actuating circuit wherein the #1 lower coil is set to the regenerative/reverse current state and the #2 upper coil is set to the flywheel state;
FIG. 17
is a diagram of an internal structure of an ECU provided for a solenoid valve actuating apparatus according to a second embodiment of the present invention;
FIG. 18
is a diagram showing an operational state of an actuating circuit wherein both of a #1 upper coil and a #2 upper coil are set to a regenerative state;
FIG. 19
is a diagram showing an operational state of the actuating circuit wherein the #1 upper coil is set to the regenerative state and the #2 upper coil is set to the flywheel state;
FIG. 20
is a diagram showing an operational state of the actuating circuit wherein a #1 lower coil is set to the regenerative state and the #2 upper coil is set to the flywheel state;
FIG. 21
is a diagram showing wave forms of exciting currents supplied to an upper coil and a lower coil when both of two solenoid valves are actuated so as to be opened and closed in the present embodiment; and
FIG. 22
is a diagram showing wave forms of exciting currents supplied to the #1 upper coil, the #1 lower coil, the #2 upper coil and a #2 lower coil when a #1 solenoid valve is actuated so as to be opened and closed and a #2 solenoid valve is maintained in the closed state.
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1
is a diagram of a system structure of a solenoid valve actuating apparatus according to an embodiment of the present invention. The solenoid valve actuating apparatus of the present embodiment is provided with an electronic control unit (hereinafter referred to as an ECU)
10
and a solenoid valve
12
. A crank position sensor (hereinafter referred to as a CP sensor) is connected to the ECU
10
.
The CP sensor
14
is a sensor which outputs a basic signal and a crank angle signal. The basic signal is output every time a crank angle of an internal combustion engine corresponds with a predetermined basic angle. The ECU
10
detects the crank angle of the internal combustion engine in accordance with the output signal of the CP sensor, and controls the solenoid valve
12
in accordance with the result of the detection.
The solenoid valve
12
has an engine valve
16
. In the present embodiment, the solenoid valve
12
is applied to the internal combustion engine of a four-cylinder-four-valve type. That is, each of cylinders of the internal combustion engine is provided with four of the solenoid valves
12
, and the engine valves
16
of two of the four solenoid valves
12
form intake valves and the engine valves
16
of the other two solenoid valves
12
form exhaust valves.
The engine valve
16
is disposed in a cylinder head
18
so as to be exposed in a combustion chamber of the internal combustion engine. An intake port (or an exhaust port)
20
is formed in the cylinder head
18
. The intake port (or the exhaust port)
20
is provided with a valve seat
22
for the engine valve
16
. The intake port (or the exhaust port)
20
communicates with the combustion chamber when the engine valve
16
is seated on the valve seat
22
, and the intake port (or the exhaust port)
20
is disconnected from the combustion chamber when the engine valve
16
is seated on the valve seat
22
.
A valve shaft
24
is fixed to the engine valve
16
. The valve shaft
24
is held by a valve guide
26
so as to be able to slide in an axial direction. The valve guide
26
is supported by the cylinder head
18
, and a lower cap
28
of the solenoid valve
12
is fixed to the valve guide
26
.
An armature shaft
30
, which is made of a non-magnetic member, is disposed on top of the valve shaft
24
. A lower retainer
32
is fixed on an upper end portion of the valve shaft
24
. A lower spring
34
is disposed between the lower retainer
32
and the lower cap
28
. The lower spring
34
exerts a resilient force so as to push the lower retainer
32
, namely, the armature shaft
30
and the engine valve
16
in an upward direction in FIG.
1
.
An upper retainer
36
is fixed on an upper end portion of the armature shaft
30
. An upper spring
38
is disposed on top of the upper retainer
36
. The upper spring
38
exerts a resilient force so as to push the upper retainer
36
, namely, the armature shaft
30
and the engine valve
16
in a downward direction in FIG.
1
.
A cylindrical upper cap
40
is disposed around the upper spring
38
. An adjuster bolt
42
is disposed on an upper end portion of the upper cap
40
. An upper end of the upper spring
38
remains in contact with the adjuster bolt
42
.
An armature
44
is joined to the armature shaft
30
. The armature
44
is an annular member which is made of a magnetic material. A first electromagnet
46
is disposed above the armature
44
. The first electromagnet
46
is provided with an upper coil
48
and an upper core
50
. A second electromagnet
52
is disposed below the armature
44
. The second electromagnet
52
is provided with a lower coil
54
and a lower core
56
.
The upper coil
48
and the lower coil
54
are connected to the ECU
10
. Exciting currents are supplied to the upper coil
48
and the lower coil
54
from the ECU
10
. The upper core
50
and the lower core
56
are members made of a magnetic material, in center portions of which the armature shaft
30
is held in a slidable way. The first electromagnet
46
and the second electromagnet
52
are held by an outer cylinder
58
so that a predetermined distance is kept between the first electromagnet
46
and the second electromagnet
52
. A neutral position of the armature
44
is so adjusted by the adjuster bolt
42
as to correspond to a middle point between the first electromagnet
46
and the second electromagnet
52
.
A description will now be given of an operation of the solenoid valve
12
.
In the solenoid valve
12
, the upper coil
48
can generate magnetic flux with the exciting current being supplied thereto. The magnetic flux generated by the upper coil
48
goes through a path which includes the upper core
50
and the armature
44
. At this point, an electromagnetic force in a direction to attract the armature
44
to the first electromagnet
46
is generated between the armature
44
and the first electromagnet
46
.
Thus, according to the solenoid valve
12
, the armature
44
, the armature shaft
30
, the engine valve
16
and so on can be moved to the side of the first electromagnet
46
by supplying the upper coil
48
with a proper exciting current. The armature shaft
30
can be moved to the side of the first electromagnet
46
until the armature
44
comes in contact with the upper core
50
. The engine valve
16
closes the intake port (or the exhaust port)
20
under conditions wherein the armature
44
remains in contact with the upper core
50
. Therefore, according to the solenoid valve
12
, the engine valve
16
can be set to a fully closed state by supplying the upper coil
48
with the proper exciting current.
When the engine valve
16
is maintained in the fully closed state, the upper spring
38
and the lower spring
34
push the armature shaft
30
toward a neutral position. When the exciting current to the upper coil
48
is cut off under these conditions, the armature shaft
30
starts a simple harmonic motion in accordance with the resilient forces of the upper spring
38
and the lower spring
34
.
According to the solenoid valve
12
, the lower coil
54
can generate magnetic flux with the exciting current being supplied thereto. The magnetic flux generated by the lower coil
54
goes through a path which includes the lower core
56
and the armature
44
. At this point, an electromagnetic force in a direction to attract the armature
44
to the second electromagnet
52
is generated between the armature
44
and the second electromagnet
52
. Thus, according to the solenoid valve
12
, the armature shaft
30
can be moved until the armature
44
comes in contact with the second electromagnet
52
by supplying the lower coil
54
with a proper exciting current to compensate for a loss of energy caused by a sliding motion of the armature shaft
30
.
The engine valve
16
is set to a fully opened state when the armature
44
comes in contact with the second electromagnet
52
. Therefore, according to the solenoid valve
12
, the engine valve
16
can be moved from the fully closed state to the fully opened state by starting the supply of the exciting current to the lower coil
54
at a predetermined timing after the exciting current to the upper coil
48
is cut off.
When the exciting current to the lower coil
54
is cut off after the engine valve
16
reaches the fully opened state, the engine valve
16
starts to move toward the fully closed position in accordance with the simple harmonic motion. Thereafter, an opening and closing operation of the engine valve
16
can be performed by repeating the timely supply of the exciting currents to the upper coil
48
and the lower coil
54
.
In the opening and closing operation of the engine valve
16
, if an electromagnetic attracting force exerted between the armature
44
and the first electromagnet
46
or the second electromagnet
52
can be made zero when the armature
44
comes in contact with the first electromagnet
46
or the second electromagnet
52
, an impact force exerted between the armature
44
and the first electromagnet
46
or the second electromagnet
52
can be reduced to prevent a generation of an impact sound, and also the durability of the solenoid valve
12
can be improved. Further, in this case, an excellent responsiveness of the solenoid valve
12
can be realized because the armature
44
can quickly be released from the first electromagnet
46
or the second electromagnet
52
. From this point of view, it is desirable to make the electromagnetic attracting force exerted between the armature
44
and the first electromagnet
46
or the second electromagnet
52
vanish promptly at a desired timing.
However, for example, a current in the same direction as the exciting current supplied to the upper coil
48
continues to flow through the upper coil
48
for a certain period of time because of a counterelectromotive force generated in the upper coil
48
even after the exciting current to the upper coil
48
is cut off. Further, the electromagnetic attracting force is exerted between the armature
44
and the first electromagnet
46
for a certain period of time because of overcurrents generated in the armature
44
and the upper core
50
even when the current flowing through the upper coil
48
is reduced to zero. Therefore, it is necessary to make the current generated by the counterelectromotive force of the upper coil
48
and further the overcurrents generated in the armature
44
and the upper core
50
vanish promptly in order to make the electromagnetic attracting force exerted between the armature
44
and the first electromagnet
46
vanish promptly.
From this point of view, it is effective to supply the upper coil
48
with the exciting current in the reverse direction for a predetermined period of time after the exciting current to the upper coil
48
is cut off. Similarly, it is effective to supply the lower coil
54
with the exciting current in the reverse direction for a predetermined period of time after the exciting current to the lower coil
54
is cut off in order to make the electromagnetic attracting force exerted between the armature
44
and the second electromagnet
52
vanish promptly. That is, an overcurrent can be offset by supplying a coil with a current in the reverse direction, which can make an electromagnetic attracting force vanish promptly.
FIG. 2
shows wave forms of the exciting currents employed in the solenoid valve
12
from the above mentioned viewpoint (FIG.
2
(
a
) and (
b
)), and a pattern of changes in position of the engine valve
16
which is obtained from the wave forms (FIG.
2
(
c
)).
As shown in FIG.
2
(
a
), during an attraction period wherein the engine valve
16
is moved from the fully opened position to the fully closed position (Periods A and B shown in FIG.
2
(
a
)), the exciting current supplied to the upper coil
48
is controlled to a maximum exciting current I
MAX
only for a predetermined period (Period A shown in FIG.
2
(
a
)), and then is so controlled, after a transition period (Period B shown in FIG.
2
(
a
)), as to correspond to the above mentioned holding current I
H
(Period C shown in FIG.
2
(
a
)) almost at the same time that the engine valve
16
reaches the fully closed position. Further, this exciting current is controlled to a demagnetizing current I
R
flowing in the reverse direction to the maximum exciting current I
MAX
when a demand to close the engine valve
16
in the fully opened position is made (Period D shown in FIG.
2
(
a
)).
In the same way as described above, as shown in FIG.
2
(
b
), during an attraction period wherein the engine valve
16
is moved from the fully closed position to the fully opened position (Periods A and B shown in FIG.
2
(
b
)), the exciting current supplied to the lower coil
54
is maintained at the predetermined value I
MAX
only for a predetermined period (Period A shown in FIG.
2
(
b
)), and then is so controlled as to be reduced toward the predetermined holding current I
H
(Period C shown in FIG.
2
(
b
)) after a transition period (Period B shown in FIG.
2
(
b
)). Further, this exciting current is controlled to the demagnetizing current I
R
flowing in the reverse direction at the point that a demand to close the engine valve
16
in the fully opened position is generated (Period D shown in FIG.
2
(
b
)).
Further, the opening and closing operation of the solenoid valve
12
in synchronism with the operation of the internal combustion engine can be performed by setting timings to supply the upper coil
48
and the lower coil
54
with the exciting currents in accordance with the output signals of the CP sensor
14
.
As described below, the above described wave forms of the exciting currents supplied to the upper coil
48
and the lower coil
54
are realized by the ECU
10
properly switching a state wherein the exciting currents in a positive direction are supplied to the upper coil
48
and the lower coil
54
and a state wherein the exciting currents in the reverse direction are supplied to the upper coil
48
and the lower coil
54
.
The solenoid valve actuating apparatus of the present embodiment is characterized in that the desired wave forms as described above can be realized by reversing the directions of the exciting currents supplied to the upper coil
48
and the lower coil
54
with a limited number of switching means provided for the ECU
10
.
A description will now be given of an internal structure of the ECU
10
with reference to FIG.
3
.
FIG. 3
is a circuit diagram showing the internal structure of the ECU
10
. As shown in
FIG. 3
, the ECU
10
is provided with a CPU
60
. An output port
68
and an input port
70
are connected to the CPU
10
through a bus line
62
. The CP sensor
14
is connected to the input port
70
.
The ECU
10
is also provided with a buffer circuit
72
and an actuating circuit
74
. As described above, the solenoid valves
12
form the intake valves and the exhaust valves of the internal combustion engine of a four-cylinder-four-valve type. That is, each of the cylinders of the internal combustion engine is provided with a pair of the solenoid valves
12
which operate as intake valves and a pair of the solenoid valves
12
which operate as exhaust valves. In the present embodiment, a total of eight pairs of the buffer circuits
72
and the actuating circuits
74
are provided, each corresponding to each pair of the intake valves provided for the same cylinder and each pair of the intake valves provided for the same cylinder. However,
FIG. 3
shows only the buffer circuit
72
and the actuating circuit
74
corresponding to a pair of the solenoid valves
12
which form, for example, the intake valves provided for one cylinder because each of the buffer circuits
72
and each of the actuating circuits
74
have the respective identical structures and operations.
The actuating circuit
74
is provided with a line terminal
76
and an ground terminal
78
. A supply voltage line and a ground voltage line of the ECU
10
are connected to the line terminal
76
and the ground terminal
78
, respectively. Therefore, a supply voltage V of the ECU
10
is supplied to the line terminal
76
. Another new power supply than the ECU
10
may be provided. The actuating circuit
74
is also provided with nine field-effect transistors (FET) which function as switching means, namely, a #1 FET
80
, a #2 FET
82
, a #3 FET
84
, a #4 FET
86
, a #5 FET
88
, a #6 FET
90
, a #7 FET
92
, a #8 FET
94
and a #9 FET
96
.
Each of drain terminals of the #1 FET
80
, the #4 FET
86
and the #7 FET
92
is connected to the line terminal
76
. A lower coil
54
(hereinafter referred to as a #1 lower coil
54
-
1
) of one solenoid valve
12
(hereinafter referred to as a #1 solenoid valve
12
-
1
) which forms the intake valve is connected between a source terminal of the #1 FET
80
and a source terminal of the #4 FET
86
. Further, an upper coil
48
(hereinafter referred to as a #2 lower coil
48
-
2
) of the other solenoid valve
12
(hereinafter referred to as a #2 solenoid valve
12
-
2
) which forms the intake valve is connected between the source terminal of the #4 FET
86
and the #7 FET
92
.
The source terminals of the #1 FET
80
, the #4 FET
86
, and the #7 FET
92
are connected to drain terminals of the #2 FET
82
, the #5 FET
88
and the #8 FET
94
, respectively. An upper coil
48
(hereinafter referred to as a #1 upper coil
48
-
1
) of the #1 solenoid valve
12
-
1
is connected between a source terminal of the #2 FET
82
and a source terminal of the #5 FET
88
. Further, a lower coil
54
(hereinafter referred to as a #2 lower coil
54
-
2
) of the #2 solenoid valve
12
-
2
is connected between the source terminal of the #5 FET
88
and a source terminal of the #8 FET
94
.
The source terminals of the #2 FET
82
, the #5 FET
88
and the #8 FET
94
are connected to drain terminals of the #3 FET
84
, the #6 FET
90
and the #9 FET
96
, respectively. Further, each of source terminals of the #3 FET
84
, the #6 FET
90
and the #9 FET
96
is connected to the ground terminal
78
.
Each of gate terminals of the #1 FET
80
through the #9 FET
96
is connected to the above described buffer circuit
72
. The buffer circuit
72
supplies a high or low level actuating signal to each of the gate terminals of the #1 FET
80
through the #9 FET
96
in accordance with a command signal from the CPU
60
. The #1 FET
80
through the #9 FET
96
are set to an ON state by the high level signal being supplied from the buffer circuit
72
to each of the gate terminals. Further, the #1 FET
80
through the #9 FET
96
are set to an OFF state by the low level signal being supplied from the buffer circuit
72
to each of the gate terminals.
Each of the #1 FET
80
through the #9 FET
96
includes therein an internal diode which allows a current to flow from the source terminal to the drain terminal. Therefore, each of the #1 FET
80
through the #9 FET
96
allows a current to flow from the source terminal side to the gate terminal side (that is, in an upward direction in
FIG. 3
) also in the OFF state.
In the solenoid valve actuating apparatus of the present embodiment, both of the two intake valves of each of the cylinders are basically opened and closed at the same timing with respect to each other. However in cases wherein the internal combustion engine is operated with a light load and a few number of revolutions, one intake valve is held in a closed state and only the other intake valve is opened and closed in the light of improvement in fuel economy. Similarly, both of the exhaust valves as well are basically opened and closed at the same timing with respect to each other, except that in some cases, one exhaust valve is maintained in the closed state and only the other exhaust valve is opened and closed, depending on an operational state of the internal combustion engine.
A description will now first be given of an operational state of the ECU
10
realized so as to supply the #1 solenoid valve
12
-
1
and the #2 solenoid valve
12
-
2
with the exciting currents having the wave forms shown in FIG.
2
(
a
) and (
b
) when the #1 solenoid valve
12
-
1
and the #2 solenoid valve
12
-
2
, which form the intake valves provided for the same cylinder, are synchronously opened and closed.
FIG.
4
through
FIG. 7
show three operational states of the ECU
10
realized so as to supply the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
with the exciting currents having current patterns shown in FIG.
2
(
a
). The FETs which are set to the ON state in FIG.
4
through FIG.
7
and in similar FIGS shown below are marked with a circle.
The state shown in
FIG. 4
is realized by setting the #1 FET
80
, the #2 FET
82
, the #4 FET
86
, the #6 FET
90
, the #8 FET
94
and the #9 FET
96
of the actuating circuit
74
to the ON state and the other FETs to the OFF state. In this state, a circuit is made from the line terminal
76
to the ground terminal
78
by way of the #1 FET
80
, #2 FET
82
, the #1 upper coil
48
-
1
and the #6 FET
90
. Thus, the #1 upper coil
48
-
1
is supplied with the exciting current flowing from the #2 FET
82
side in the direction of the #6 FET
90
side (in a rightward direction in
FIG. 4
; hereinafter this direction is referred to as a positive direction of the #1 upper coil
48
-
1
). Hereinafter, a state wherein a coil is supplied with an exciting current in a positive direction is referred to as a powered state of the coil. Further, in the state shown in
FIG. 4
, a circuit is made from the line terminal
76
to the ground terminal
78
by way of the #4 FET
86
, the #2 upper coil
48
-
2
, the #8 FET
94
and the #9 FET
96
. Thus, the #2 upper coil
48
-
2
is supplied with the exciting current flowing from the #4 FET
86
side in the direction of the #8 FET
94
side (in the rightward direction in
FIG. 4
; hereinafter this direction is referred to as a positive direction of the #2 upper coil
48
-
2
). That is, the #2 upper coil
48
-
2
is also set to the powered state. The magnitude of a current flowing through a coil in the powered state corresponds to the above described maximum exciting current I
MAX
.
In the state shown in
FIG. 4
, the exciting current flowing through the #1 lower coil
54
-
1
is substantially zero since both ends of the #1 lower coil
54
-
1
are short-circuited by the #1 FET
80
and the #4 FET
86
set to the ON state. Similarly, the exciting current flowing through the #2 lower coil
54
-
2
is substantially zero since both ends of the #2 lower coil
54
-
2
are short-circuited by the #6 FET
90
and the #9 FET
96
set to the ON state.
Further, as described above, in the state shown in
FIG. 4
, the maximum exciting current I
MAX
supplied to the #1 upper coil
48
-
1
flows through the #1 FET
80
, the #2 FET
82
and the #6 FET
90
, while the maximum exciting current I
MAX
supplied to the #2 upper coil
48
-
2
flows through the #4 FET
86
, the #8 FET
94
and the #9 FET
96
. That is, heat generation in the FETs can be controlled because the maximum exciting currents I
MAX
supplied to the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
do not flow through the same FET.
The state shown in
FIG. 5
is realized by setting the #1 FET
80
and the #2 FET
82
of the actuating circuit
74
to the ON state and the other FETs to the OFF state. In this state, a closed circuit is made, starting from and returning to the #1 FET
80
by way of the #2 FET
82
, a first upper coil
48
-
1
, the internal diode of the #5 FET
88
, a second upper coil
48
-
2
and the internal diode of the #7 FET
92
. The directions of the above described currents in the positive direction of the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
correspond to the direction of this closed circuit. Therefore, by switching from the powered state shown in
FIG. 4
to the state shown in
FIG. 5
, currents in the positive direction generated by the counterelectromotive forces of the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
, namely, flywheel currents can flow through the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
without a current being supplied from the line terminal
76
to the actuating circuit
74
. Hereinafter, a state wherein the flywheel current flows through a coil is referred to as a flywheel state of the coil. In the flywheel state, the magnitude of a current flowing through a coil is gradually diminished by a circuit resistance.
The state shown in
FIG. 6
is realized by setting the #4 FET
86
and the #6 FET
90
to the ON state and the other FETs to the OFF state. In this state, a closed circuit is made, starting from and returning to the #6 FET
90
by way of the internal diode
84
of the #3 FET
84
and the #1 upper coil
48
-
1
. Further, in the state shown in
FIG. 6
, a closed circuit is made, starting from and returning to the #4 FET
86
by way of the #2 upper coil
48
-
2
and the internal diode of the #7 FET
92
. The directions of the currents in the positive direction of the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
correspond to the directions of these closed circuits. Therefore, also in the state shown in
FIG. 6
, both of the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
are set to the flywheel state as in the state shown in FIG.
5
.
The state shown in
FIG. 7
is realized by setting the #3 FET
84
, the #5 FET
88
and the #7 FET
92
to the ON state and the other FETs to the OFF state. In this state, a circuit is made from the line terminal
76
to the ground terminal
78
by way of the #7 FET
92
, the #2 upper coil
48
-
2
, the #5 FET
88
, the #1 upper coil
48
-
1
and the #3 FET
84
. In this case, in a state wherein the sum of the counterelectromotive forces generated in the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
is larger than the supply voltage V supplied to the line terminal
76
, the currents in the positive direction flowing through the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
are promptly reduced to zero by being withdrawn to the power supply side as a regenerative energy. On the other hand, in a state wherein the sum of the above mentioned counterelectromotive forces is smaller than the supply voltage V, the #2 upper coil
48
-
2
and the #1 upper coil
48
-
1
are supplied with the exciting current flowing from the #7 FET
92
side in the direction of the #5 FET
88
side (in a leftward direction in
FIG. 7
) and the exciting current flowing from the #5 FET
88
side in the direction of the #3 FET
84
side (in the leftward direction in FIG.
7
), respectively. These exciting currents supplied to the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
are in the reverse direction to the currents in the positive direction. That is, in the state shown in
FIG.7
, the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
can be supplied with the demagnetizing currents I
R
in the reverse direction. Hereinafter, a state wherein a current generated by an counterelectromotive force of a coil is withdrawn to the power supply side as a regenerative energy or an exciting current in the reverse direction is supplied is referred to as a regenerative/reverse current state of the coil.
As described above, the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
are set to the powered state in the state shown in
FIG. 4
, to the flywheel state in the state shown in
FIG. 5
or
FIG. 6
, and to the regenerative/reverse current state in the state shown in FIG.
7
. Therefore, the ECU
10
can supply the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
with the maximum exciting currents I
MAX
by realizing the state shown in
FIG. 4
during Period A shown in FIG.
2
(
a
), and can reduce the exciting currents supplied to the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
from the I
MAX
to the I
H
by properly switching and realizing the states shown in FIG.
4
through
FIG. 7
during Period B shown in FIG.
2
(
a
). Further, the ECU
10
can hold the exciting currents supplied to the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
to the holding currents I
H
by properly switching and realizing the state shown in FIG.
4
and the state shown in
FIG. 5
or
FIG. 6
during Period C shown in FIG.
2
(
a
), and can supply the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
with the demagnetizing currents I
R
by realizing the state shown in
FIG. 7
during Period D shown in FIG.
2
(
a
).
Thus, in the present embodiment, the exciting currents supplied to the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
can be controlled in accordance with the wave forms shown in FIG.
2
(
a
) and (
b
) by the ECU properly switching and realizing the above mentioned states shown in FIG.
4
through FIG.
7
.
A description has so far been given of the case wherein the exciting current supplied to the upper coil
48
is controlled, while states corresponding to FIG.
4
through
FIG. 7
, respectively can be formed of the lower coil
54
by setting to the ON state the FETs which are disposed symmetrically in a lateral direction in the drawings with the FETs set to the ON state in the states shown in FIG.
4
through FIG.
7
.
That is, the #1 lower coil
54
-
1
and the #2 lower coil
54
-
2
can be set to the powered state by setting to the ON state the #2 FET
82
, the #3 FET
84
, the #4 FET
86
, the #6 FET
90
, the #7 FET
92
and the #8 FET
94
in correspondence to the state shown in
FIG. 4. A
positive direction of the #1 lower coil
54
-
1
is the direction toward the #2 FET
82
side from the #4 FET
86
side (in a leftward direction in the drawing), and a positive direction of the #2 lower coil
54
-
2
is the direction toward the #6 FET
90
side from the #8 FET
94
side (in the leftward direction in the drawing).
Further, the #1 lower coil
54
-
1
and the #2 lower coil
54
-
2
can be set to the flywheel state by setting the #7 FET
92
and the #8 FET
94
to the ON state in correspondence to the
FIG. 5
or by setting the #4 FET
86
and the #6 FET to the ON state as in the state shown in FIG.
6
. Moreover, the #1 lower coil
54
-
1
and the #2 lower coil
54
-
2
can be set to the regenerative/reverse current state by setting to the ON state the #1 FET
80
, the #5 FET
88
and the #9 FET
96
in correspondence to the state shown in FIG.
7
.
A description will now be given of an operation of the ECU
10
when one intake valve provided for a cylinder (for example, the #2 solenoid valve
12
-
2
) is held in the closed state, and the other intake valve provided for the same cylinder(for example, the #1 solenoid valve
12
-
1
) is actuated so as to be opened and closed.
FIG. 8
shows wave forms of the exciting currents supplied to the #1 upper coil
48
-
1
, the #1 lower coil
54
-
1
, the #2 upper coil
54
-
1
and the #2 lower coil
54
-
2
, respectively so as to hold the #2 solenoid valve
12
-
2
in the closed state and to actuate the #1 solenoid valve
12
-
1
so that the #1 solenoid valve
12
-
1
will be opened and closed. As shown in FIG.
8
(
a
) and (
b
), the #1 solenoid valve
12
-
1
is actuated so as to be opened and closed by supplying the #1 upper coil
48
-
1
and the #1 lower coil
54
-
1
with the exciting currents having the same wave forms as shown in FIG.
2
(
a
) and (
b
). On the other hand, as shown in FIG.
8
(
c
) and (
d
), the #2 solenoid valve is held in the closed state by keeping the exciting current supplied to the #2 upper coil
48
-
2
as large as the holding current I
H
and by rendering the exciting current supplied to the #2 lower coil
54
-
2
zero. However, the exciting current supplied to the #2 upper coil
48
-
2
is momentarily increased just before the demagnetizing current I
R
is supplied to the #1 upper coil
48
-
1
or the #1 lower coil
54
-
1
. The reason for this will be discussed later.
The wave forms shown in
FIG. 8
can be realized by properly switching states shown in FIG.
9
through
FIG. 16
in addition to the above described state shown in FIG.
4
and the above described state shown in
FIG. 5
or FIG.
6
. A description will first be given of a case wherein the exciting current is supplied to the #1 upper coil
48
-
1
(Periods A, B, C and D shown in FIG.
8
(
a
)). The wave forms of Periods A, B, C and D shown in FIG.
8
(
a
) are realized by properly switching the states shown in FIG.
9
through
FIG. 11
in addition to the state shown in FIG.
4
and the state shown in
FIG. 5
or FIG.
6
.
The state shown in
FIG. 9
is realized by setting the #1 FET
80
, the #2 FET
82
, the #4 FET
86
and the #6 FET
90
to the ON state and the other FETs to the OFF state. In this state, a circuit is made from the line terminal
76
to the ground terminal
78
by way of the #1 FET
80
, the #2 FET
82
, the #1 upper coil
48
-
1
and the #6 FET
90
. Thus, the maximum exciting current I
MAX
in the positive direction is supplied from the line terminal
76
to the #1 upper coil
48
-
1
. That is, the #1 upper coil
48
-
1
is set to the powered state. Further, in the state shown in
FIG. 9
, a closed circuit is made, starting from and returning to the #4 FET
86
by way of the #2 upper coil
48
-
2
and the internal diode of the #7 FET
92
. Thus, the flywheel current can flow through the #2 upper coil
48
-
2
. That is, the #2 upper coil
48
-
2
is set to the flywheel state.
The state shown in
FIG. 10
is realized by setting the #4 FET
86
, the #6 FET
90
, the #8 FET
94
and the #9 FET
96
to the ON state and the other FETs to the OFF state. In this state, a closed circuit is made, starting from the #6 FET
90
and returning to the #3 FET
90
by way of the internal diode of the #3 FET
84
and the #1 upper coil
48
-
1
. Thus, the #1 upper coil
48
-
1
is set to the flywheel state. Further, in the state shown in
FIG. 10
, a circuit is made from the line terminal
76
to the ground terminal
78
by way of the #4 FET
86
, the #2 upper coil
48
-
2
, the #8 FET
94
and the #9 FET
96
. Thus, the #2 upper coil
48
-
2
is set to the powered state.
The state shown in
FIG. 11
is realized by setting to the ON state the #3 FET
84
, the #4 FET
86
and the #5 FET
88
. In this state, a circuit is made from the line terminal
76
to the ground terminal
78
by way of the #4 FET
86
, the #5 FET
88
, the #1 upper coil
48
-
1
and the #3 FET
84
. Thus, the #1 upper coil is set to the regenerative/reverse current state. Further, in the state shown in
FIG. 11
, a closed circuit is made, starting from and returning to the #4 FET
86
by way of the #2 upper coil
48
-
2
and the internal diode of the #7 FET
92
. Thus, the #2 upper coil
48
-
2
is set to the flywheel state.
As described above, both of the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
are set to the powered state in the state shown in FIG.
4
. On the other hand, in the state shown in
FIG. 9
, the #1 upper coil
48
-
1
is set to the powered state while the #2 upper coil
48
-
2
is set to the flywheel state. Therefore, the wave form of the Period A shown in FIG.
8
(
a
) can be realized by switching the states shown in FIG.
4
and in
FIG. 9
so that the current supplied to the upper coil
48
-
2
will correspond to the holding current I
H
.
Further, in the states shown in
FIG. 4
,
FIG. 5
(or FIG.
6
), FIG.
9
and
FIG. 10
, all the combinations of the powered state and the flywheel state are realized with respect to the #1 upper coil
48
-
1
and the #2 upper coil
482
. Moreover, in the state shown in
FIG. 11
, a flywheel flows through the #2 upper coil
48
-
2
and a current in the reverse direction is supplied to the #1 upper coil
48
-
1
. Therefore, the wave form of Period B shown in FIG.
8
(
a
) can be realized by switching the above described five states so that the exciting current supplied to the #1 upper coil
48
-
1
will be reduced to the holding current I
H
with a desired slope and the exciting current supplied to the #2 upper coil
48
-
2
will be held to the holding current I
H
.
Further, during Period C shown in FIG.
8
(
a
), the exciting currents supplied to the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
are held to the holding current I
H
. Therefore, the wave form of Period C shown in FIG.
8
(
a
) can be realized by switching the states shown in FIG.
4
and in FIG.
5
.
Moreover, a current in the reverse direction I
R
is supplied to the #1 upper coil
48
-
1
during Period D shown in FIG.
8
(
a
). Therefore, the wave form of Period D shown in FIG.
8
(
a
) can be realized by forming the state shown in FIG.
11
. However, in the state shown in
FIG. 11
, since the #2 upper coil
48
-
2
is set to the flywheel state, the magnitude of the exciting current is decreased with the passage of time. Therefore, in the present embodiment, the magnitude of the exciting current supplied to the #2 upper coil
48
-
2
is increased by a predetermined amount in expectation of the decrease in the exciting current during the Period D shown in FIG.
8
(
a
) just before the Period D is entered on (that is, at the end of the Period C). The increase in the exciting current supplied to the #2 upper coil
48
-
2
in the Period C shown in FIG.
8
(
a
) can be realized, for example, by increasing the time ratio of the state shown in
FIG. 10
(the state wherein the #2 upper coil
48
-
2
is set to the powered state) relative to the time ratio of the state shown in
FIG. 5
or
FIG. 6
(the state wherein the #2 upper coil
48
-
2
is set to the flywheel state) in switching the above described five states.
A description will now be given of a case wherein the exciting current is supplied to the #1 lower coil
54
-
1
(Periods A, B, C and D shown in FIG.
8
(
b
)). The wave forms of Periods A, B, C and D shown in FIG.
8
(
b
) are realized by properly switching the states shown in FIG.
12
through FIG.
16
.
The state shown in
FIG. 12
is realized by setting the #2 FET
82
, the #3 FET
84
, the #4 FET
86
, the #8 FET
94
and the #9 FET
96
to the ON state and the other FETs to the OFF state. In this state, a circuit is made from the line terminal
76
to the ground terminal
78
by way of the #4 FET
86
, the #1 lower coil
54
-
1
, the #2 FET
82
and the #3 FET
84
, and a circuit is made from the line terminal
76
to the ground terminal
78
by way of the #4 FET
86
, the #2 upper coil
48
-
2
, the #8 FET
94
and the #9 FET
96
. Thus, both of the #1 lower coil
54
-
1
and the #2 upper coil
48
-
2
are set to the powered state.
The state shown in
FIG. 13
is realized by setting the #2 FET
82
, the #3 FET
84
and the #4 FET
86
to the ON state and the other FETs to the OFF state. In this state, a circuit is made from the line terminal
76
to the ground terminal
78
by way of the #4 FET
86
, the #1 lower coil
54
-
1
, the #2 FET
82
and the #3 FET
84
. Thus, the #1 lower coil
54
-
1
is set to the powered state. Further, in the state shown in
FIG. 13
, a closed circuit is made, starting from and returning to the #4 FET
86
by way of the #2 upper coil
48
-
2
and the internal diode of the #7 FET
92
. Thus, the #2 upper coil
48
-
2
is set to the flywheel state.
The state shown in
FIG. 14
is realized by setting the #4 FET
86
, the #8 FET
94
and the #9 FET
96
to the ON state and the other FETs to the OFF state. In this state, a closed circuit is made, starting from and returning to the #4 FET
86
by way of the #1 lower coil
54
-
1
and the internal diode of the #1 FET
80
. Thus, the #1 lower coil
54
-
1
is set to the flywheel state. Further, in the state shown in
FIG. 14
, a circuit is made from the line terminal
76
to the ground terminal
78
by way of the #4 FET
86
, the #2 upper coil
48
-
2
, the #8 FET
94
and the #9 FET
96
. Thus, the #2 upper coil
48
-
2
is set to the powered state.
The state shown in
FIG. 15
is realized by setting only the #4 FET
86
to the ON state and the other FETs to the OFF state. In this state, a closed circuit is made, starting from and returning to the #4 FET
86
by way of the #1 lower coil
54
-
1
and the internal diode of the #1 FET
80
, and a closed circuit is made, starting from and returning to the #4 FET
86
by way of the #2 upper coil
48
-
2
and the internal diode of the #7 FET
92
. Thus, both of the #1 lower coil
54
-
1
and the #2 upper coil
48
-
2
are set to the flywheel state.
The state shown in
FIG. 16
is realized by setting the #1 FET
80
, the #5 FET
88
, the #6 FET
90
, the #8 FET
94
and the #9 FET
96
to the ON state and the other FETs to the OFF state. In this state, a circuit is made from the line terminal
76
to the ground terminal
78
by way of the #1 FET
80
, the #1 lower coil
54
-
1
, the #5 FET
88
and the #6 FET
90
. Thus, the #1 lower coil
54
-
1
is set to the regenerative/reverse current state. Further, in the state shown in
FIG. 16
, a closed circuit is made, starting from and returning to the #6 FET
90
by way of the #5 FET
88
, the #2 upper coil
48
-
2
, the #8 FET
94
and the #9 FET
96
. Thus, the #2 upper coil
48
-
2
is set to the flywheel state.
As described above, both of the #1 lower coil
54
-
1
and the #2 upper coil
48
-
2
are set to the powered state in the state shown in FIG.
12
. On the other hand, in the state shown in
FIG. 13
, the #1 lower coil
54
-
1
is set to the powered state, while the #2 upper coil
48
-
2
is set to the flywheel state. Therefore, the wave form of Period A shown in FIG.
8
(
b
) is realized by switching the states shown in FIG.
12
and in
FIG. 13
so that the exciting current supplied to the #2 upper coil
48
-
2
will be maintained to the holding current I
H
.
Further, according to the states shown in
FIG. 12
,
FIG. 13
, FIG.
14
and
FIG. 15
, all the combinations of the powered state and the flywheel state are realized with respect to the #1 lower coil
54
-
1
and the #2 upper coil
482
. Moreover, in the state shown in
FIG. 16
, the #2 upper coil
48
-
2
is set to the flywheel state, and the #1 lower coil
54
-
1
is set to the regenerative/reverse current state. Therefore, the wave form of Period B shown in FIG.
8
(
b
) can be realized by switching the above described five states so that the exciting current supplied to the #1 lower coil
54
-
1
will be reduced to the holding current I
H
with a desired slope and the exciting current supplied to the #2 upper coil
48
-
2
will be held to the holding current I
H
. Further, during Period C shown in FIG.
8
(
b
), each of the exciting currents supplied to the #1 lower coil
48
-
1
and the #2 upper coil
48
-
2
is held to the holding current I
H
. Therefore, the wave form of Period C shown in FIG.
8
(
a
) is realized by switching the state shown in FIG.
12
and in FIG.
15
.
Moreover, the current in the reverse direction I
R
is supplied to the #1 lower coil
54
-
1
during Period D shown in FIG.
8
(
b
). Therefore, the wave form of Period D shown in FIG.
8
(
b
) can be obtained by realizing the state shown in FIG.
16
. However, in the state shown in
FIG. 16
, the magnitude of the exciting current flowing through the #2 upper coil
48
-
2
is decreased with the passage of time because the #2 upper coil
48
-
2
is set to the flywheel state. Therefore, in the present embodiment, the magnitude of the exciting current supplied to the #2 upper coil
48
-
2
is increased by a predetermined amount in expectation of the decrease in the exciting current just before Period D is entered on (that is, at the end of Period C). The increase in the exciting current supplied to the #2 upper coil
48
-
2
in Period C shown in FIG.
8
(
b
) is realized, for example, by increasing the time ratio of the state shown in
FIG. 14
(the state wherein the #2 upper coil
48
-
2
is set to the powered state) relative to the time ratio of the state shown in
FIG. 15
(the state wherein the #2 upper coil
48
-
2
is set to the flywheel state) in switching the above described states shown in FIG.
12
through FIG.
16
.
A description has so far been given of the case wherein the #2 solenoid valve
12
-
2
is held in the closed state and the #1 solenoid valve
12
-
1
is actuated so as to be opened and closed, while it is also practicable that the #1 solenoid valve
12
-
1
is held in the closed state and the #2 solenoid valve
12
-
2
is actuated so as to be opened and closed. That is, states corresponding to the states shown in FIG.
9
through
FIG. 16
, respectively are realized by setting to the ON state the FETs which are disposed in centrosymmetrical positions with respect to the positions of the FETs which are set to the ON state in the states shown in FIG.
9
through FIG.
16
.
For example, the #1 upper coil
48
-
1
can be set to the flywheel state and the #2 upper coil
48
-
2
can be set to the powered state by setting to the ON state the #9 FET
96
, the #8 FET
94
, the #6 FET
90
and the #4 FET
86
, which are in the centrosymmetrical positions respectively with respect to the positions of the #1 FET
80
, the #2 FET
82
, the #4 FET
86
and the #6 FET
90
, which are set to the ON state in the state shown in FIG.
9
. Similarly, in correspondence to the state shown in
FIG. 10
, the #1 upper coil
48
-
1
can be set to the powered state and the #2 upper coil
48
-
2
can be set to the flywheel state by setting to the ON state the #6 FET
90
, the #4 FET
86
, the #2 FET
82
and the #1 FET;
in correspondence to the state shown in
FIG. 11
, the #1 upper coil
48
-
1
can be set to the flywheel state and the #2 upper coil
48
-
2
can be set to the regenerative/reverse current state by setting to the ON state the #7 FET
92
, the #6 FET
90
, and the #5 FET
88
;
in correspondence to the state shown in
FIG. 12
, both of the #1 upper coil
48
-
1
and the #2 lower coil
54
-
2
can be set to the powered state by setting to the ON state the #8 FET
94
, the #7 FET
92
, the #6 FET
90
, the #2 FET
82
and the #1 FET
80
;
in correspondence to the state shown in
FIG. 13
, the #1 upper coil
48
-
1
can be set to the flywheel state and the #2 lower coil
54
-
2
can be set to the powered state by setting to the ON state the #8 FET
94
, the #7 FET
92
and the #6 FET
90
;
in correspondence to the state shown in
FIG. 14
, the #1 upper coil
48
-
1
can be set to the powered state and the #2 lower coil
54
-
2
can be set to the flywheel state by setting to the ON state the #6 FET
90
, the #2 FET
82
and the #1 FET
80
;
in correspondence to the state shown in
FIG. 15
, both of the #1 upper coil
48
-
1
and the #2 lower coil
54
-
2
can be set to the flywheel state by setting only the #6 FET
90
to the ON state;
in correspondence to the state shown in
FIG. 16
, the #1 upper coil
48
-
1
can be set to the flywheel state and the #2 lower coil
54
-
2
can be set to the regenerative/reverse current state by setting to the ON state the #9 FET
96
, the #5 FET
88
, the #4 FET
86
, the #2 FET
82
and the #1 FET
80
.
Then, by means of properly switching the above described states corresponding to the states of FIG.
9
through
FIG. 16
, respectively as in the above described case wherein the #2 solenoid valve
12
-
2
is held in the closed state while the #1 solenoid valve
12
-
1
is actuated so as to be opened and closed, the #2 solenoid valve
12
-
2
can be actuated so as to be opened and closed by supplying the #2 upper coil
48
-
2
and the #2 lower coil
54
-
2
with the exciting currents having the same wave forms as those of FIG.
8
(
a
) and (
b
) while the exciting current supplied to the #1 upper coil
48
-
1
is held to the holding current I
H
(that is, while the #1 solenoid valve
12
-
1
is held in the closed state).
As described above, according to the present embodiment, each of the #1 upper coil
48
-
1
, the #1 lower coil
54
-
1
, the #2 upper coil
48
-
2
and the #2 lower coil
54
-
2
can be supplied with currents in both of the positive and the reverse directions. Thereby, the exciting currents supplied to the coils can be controlled in accordance with the current patterns shown in
FIG. 3
or FIG.
8
. Thus, according to the solenoid valve control apparatus of the present embodiment, the electromagnetic attracting force exerted between the armature
44
and the first electromagnet
46
or the second electromagnet
52
can be made to promptly vanish when the armature
44
comes in contact with the first electromagnet
46
or the second electromagnet
52
. Therefore, the impact sound generated by the opening and closing operation of the solenoid valve
12
can be controlled and the durability of the solenoid valve
12
can be improved. Further, the excellent responsiveness of the solenoid valve
12
can be realized.
In the present embodiment, the above described performance is realized by forming the one actuating circuit
74
for a total of four solenoid coils provided for a pair of solenoid valves which form intake valves or exhaust valves provided for the same cylinder. That is, the exciting currents supplied to these four solenoid coils can be controlled by the nine switching means, namely, the #1 FET
80
through the #9 FET
96
. On the other hand, when one solenoid valve is controlled by a bridged-H-type circuit as in the above described prior art, sixteen switching means are required for four solenoid coils. Therefore, a total of one hundred and twenty-eight switching means will be required when the conventional structure is applied to an internal combustion engine of a four-cylinder-four-valve type, while seventy-two switching means are sufficient according to the present embodiment.
Thus, according to the present embodiment, the above described performance can be realized with the far smaller required number than ever of switching means by providing the switching means of the FET
80
through the FET
96
for each of the solenoid valves
12
, which are actuated to be opened and closed in synchronism with each other.
A description will now be given of a second embodiment of the present invention. A solenoid valve actuating apparatus of the present embodiment is realized by employing an ECU
110
instead of the ECU
10
in the solenoid valve control apparatus of the above described first embodiment.
FIG. 17
is a circuit diagram showing an internal structure of the ECU
110
of the present embodiment. In
FIG. 17
, the same structural portions as those in
FIG. 3
are provided with the same reference numerals and the descriptions thereof are omitted or simplified. As shown in
FIG. 17
, the ECU
110
is provided with an actuating circuit
174
. The actuating circuit
174
is realized by employing a diode
188
instead of the #5 FET
88
in the actuating circuit
74
of the above described embodiment. The diode
188
is disposed so as to allow a current to flow from the ground terminal
78
side in the direction of the line terminal
76
.
Also in the present embodiment, basically, by setting to the ON state the same FETs that are set to the ON state in the states shown in FIG.
4
through FIG.
7
and FIG.
9
through
FIG. 16
of the above described first embodiment, the same states as those states can be realized. Among those states, the #5 FET
88
is set to the OFF state in the states shown in
FIG. 4
,
FIG. 5
,
FIG. 6
,
FIG. 9
,
FIG. 10
,
FIG. 12
,
FIG. 13
, FIG.
14
and FIG.
15
. The same states as those states can be realized by the diode
188
of the present embodiment achieving the same function as the internal diode of the #5 FET
88
. On the other hand, the #5 FET
88
is set to the ON state in the states shown in
FIG. 7
, FIG.
11
and
FIG. 16
, while in the present embodiment, the same states as shown in
FIG. 7
, FIG.
11
and
FIG. 16
cannot be realized because the diode
188
is provided instead of the #5 FET
88
. A description will now be given of states corresponding to
FIG. 7
, FIG.
11
and
FIG. 16
of the above described first embodiment with reference to FIG.
18
through FIG.
20
.
FIG. 18
shows a state corresponding to above described
FIG. 7
in the present embodiment. The state shown in
FIG. 18
is realized by setting every FET to the OFF state. In this state, a circuit is made from the ground terminal
78
to the line terminal
76
by way of the internal diode of the #3 FET
84
, the #1 upper coil
48
-
1
, the diode
188
, the #2 upper coil
48
-
2
and the internal diode of the #7 FET
92
. Therefore, when the sum of the counterelectromotive forces generated in the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
is larger than the supply voltage V, currents flowing through these coils can be withdrawn to the power supply side as a regenerative energy as in the state shown in FIG.
7
. However, as is different from the state shown in
FIG. 7
, the #1 upper coil
48
-
1
and the #2 upper coil
48
-
2
cannot be supplied with the demagnetizing currents I
R
in the reverse direction even with the #3 FET
84
and the #7 FET
92
being set to the ON state since the diode
188
prevents a current from flowing from the #2 upper coil
48
-
2
side to the #1 upper coil
48
-
1
side. Therefore, the #3 FET
84
and the #7 FET
92
are set to the OFF state in the state shown in FIG.
18
. However, operations will remain the same if the #3 FET
84
and the #7 FET
92
are set to the ON state. Hereinafter, a state wherein a current flowing through a coil can be withdrawn as a regenerative energy, but a current in the reverse direction cannot be supplied is referred to as a regenerative state of the coil.
FIG. 19
shows a state corresponding to above described
FIG. 11
in the present embodiment. The state shown in
FIG. 19
is realized by setting the #4 FET
86
to the ON state and the other FETs to the OFF state. In this state, as in the state shown in
FIG. 11
, a closed circuit is made, starting from and returning to the #4 FET
86
by way of the #2 upper coil
48
-
2
and the internal diode of the #7 FET
92
. Thus, the #2 upper coil
48
-
2
is set to the flywheel state. Further, in the state shown in
FIG. 19
, a circuit is made from the ground terminal
78
to the line terminal
76
by way of the #3 FET
84
, the #1 upper coil
48
-
1
, the diode
188
and the #4 FET
86
. Thus, when the counterelectromotive force of the #1 upper coil
48
-
1
is larger than the supply voltage, a current flowing through the #1 upper coil
48
-
1
can be withdrawn to the power supply side as a regenerative energy as in the state shown in FIG.
11
. However, as is different from the state shown in
FIG. 11
, the #1 upper coil
48
-
1
cannot be supplied with a current in the reverse direction even with the #3 FET
84
being set to the ON state since the diode
188
prevents a current from flowing from the #4 FET
86
side to the #1 upper coil
48
-
1
side. That is, in the state shown in
FIG. 19
, the #1 upper coil
48
-
1
is set to the regenerative state whether the #3 FET
84
is set to the ON state or to the OFF state.
FIG. 20
shows a state corresponding to above described
FIG. 16
in the present embodiment. The state shown in
FIG. 20
is realized by setting the #8 FET
94
and the #9 FET
96
to the ON state and the other FETs to the OFF state. In this state, as in the state shown in
FIG. 16
, a closed circuit is made, starting from and returning to the #8 FET
94
by way of the #9 FET
96
, the internal diode of the #6 FET
90
, the diode
188
and the #2 upper coil
48
-
2
. Thus, the #2 upper coil
48
-
2
is set to the flywheel state. Further, in the state shown in
FIG. 20
, a circuit is made from the ground terminal
78
to the line terminal
76
by way of the internal diode of the #6 FET
90
, the diode
188
, the #1 lower coil
54
-
1
and the internal diode of the #1 FET
80
. Thus, when the counterelectromotive force of the #1 lower coil
54
-
1
is larger than the supply voltage V, a current flowing through the #1 lower coil
54
-
1
can be withdrawn to the power supply side as a regenerative energy as in the state shown in FIG.
16
. However, as is different from the state shown in
FIG. 16
, the #1 lower coil
54
-
1
cannot be supplied with a current in the reverse direction even with the #1 FET
80
and the #6 FET
90
being set to the ON state since the diode
188
prevents a current from flowing from the #1 lower coil
54
-
1
side to the #6 FET
90
side. That is, in the state shown in
FIG. 20
, the #1 lower coil is set to the regenerative state whether the #1 FET
80
and the #6 FET
90
are set to the ON state or to the OFF state.
As described above, in the present embodiment, no solenoid coil of the #1 upper coil
48
-
1
, the #1 lower coil
54
-
1
, the #2 upper coil
48
-
2
and the #2 lower coil
54
-
2
can be supplied with the demagnetizing current I
R
in the reverse direction. However, in the above described states shown in FIG.
18
through
FIG. 20
, the currents flowing through these solenoid coils can be withdrawn to the power supply side as a regenerative energy by energizing these solenoid coils in the reverse direction. Therefore, the currents flowing through the solenoid coils can be reduced promptly by realizing the states in FIG.
18
through FIG.
20
.
FIG. 21
shows wave forms of the exciting currents supplied to the upper coil
48
and the lower coil
54
when the #1 solenoid valve
12
-
1
and the #2 solenoid valve
12
-
2
are actuated in synchronism with each other. The wave forms during Periods A, B and C shown in FIG.
21
(
a
) can be realized, as in the case of the above described first embodiment, by properly switching the state corresponding to
FIG. 4
, the state corresponding to
FIG. 5
or FIG.
6
and the state shown in FIG.
18
. Further, the wave forms shown in FIG.
21
(
b
) can be realized by properly switching a state wherein set to the ON state are the FETs which are disposed symmetrically in a vertical direction with the FETs set to the ON state in the state corresponding to FIG.
4
and in the state corresponding to
FIG. 5
or
FIG. 6
, and the state shown in
FIG. 18
(used in common for the upper coil
48
and the lower coil
54
as every FET is set to the OFF state in the state shown in FIG.
18
).
As described above, however, as the solenoid coils cannot be supplied with the currents in the reverse direction in the present embodiment, the exciting current supplied to the upper coil
48
, as shown in FIG.
21
(
a
), never becomes negative during Period D, which is entered on after Period C, wherein the exciting current is held at a predetermined value I
H
. However, by realizing the above described state shown in
FIG. 18
during this Period D, the current flowing through the upper coil
48
can be withdrawn to the power supply side as a regenerative energy, which enables the exciting current to promptly be reduced to zero. Also during Period D with respect to the lower coil
54
shown in FIG.
21
(
b
), the exciting current flowing through the lower coil
54
can promptly be reduced to zero by realizing the state shown in FIG.
18
.
FIG. 22
shows wave forms of the exciting currents supplied to the #1 upper coil
48
-
1
, the #1 lower coil
54
-
1
and the #2 upper coil
48
-
2
when the #2 solenoid valve
12
-
2
is held in the closed state and only the #1 solenoid valve
12
-
1
is opened and closed. The wave forms can be realized by properly switching the states corresponding to
FIG. 4
,
FIG. 5
or
FIG. 6
,
FIG. 9
, FIG.
10
and FIG.
12
through
FIG. 15
, respectively, the state shown in
FIG. 19
corresponding to
FIG. 11
, and the state shown in
FIG. 20
corresponding to FIG.
16
. Also with respect to the wave forms shown in
FIG. 22
, the currents flowing through the upper coil
48
-
1
and the #1 lower coil
54
-
1
can promptly be reduced to zero by realizing the state shown in
FIG. 19
or
FIG. 20
during Period D, which is entered on after Period C. In this case, in the states shown in FIG.
19
and
FIG. 20
, the exciting current flowing through the #2 upper coil
48
-
2
is reduced during Period D because the #2 upper coil
48
-
2
is set to the flywheel state. Therefore, the exciting current supplied to the #2 upper coil
48
-
2
is increased by a predetermined amount relative to the holding current I
H
in expectation of the decrease just before Period D is entered on.
The #2 solenoid valve
12
-
2
can be held in the closed state and only the #1 solenoid valve
12
-
1
can be opened and closed by switching states wherein set to the ON state are the FETs disposed centrosymmetrically with the FETs which are set to the ON state in the above described states employed to realize the wave forms shown in FIG.
22
.
As described above, according to the present embodiment, a current flowing through a solenoid coil can promptly be reduced to zero by realizing the states shown in FIG.
18
through
FIG. 20
after an exciting current to the solenoid coil is cut off. Therefore, the electromagnetic attracting force exerted between a plunger
44
and the first electromagnet
46
or the second electromagnet
52
can be made to promptly vanish after the plunger
44
comes in contact with the first electromagnet
46
or the second electromagnet
52
although the effect is so much less, in comparison with the above described first embodiment, for the fact that the solenoid valve is not supplied with a current in the reverse direction.
The actuating circuit
174
of the present embodiment is realized by employing the relatively inexpensive diode
188
instead of the #5 FET
88
of the above described first embodiment. Therefore, in the present embodiment, it is possible to realize the solenoid valve control apparatus having the above described performance, attempting to further reduce the cost of the apparatus.
In the above described first and second embodiments, the descriptions have been made of the case wherein the two intake valves and the two exhaust valves are provided for each of the cylinders of the internal combustion engine, while the present invention is not limited to this case and can also be applied to an internal combustion engine having each of cylinders provided with two intake valves and one exhaust valve. In such a case, the number of the switching means for actuating the intake valves can be reduced by applying the above described structure only to the intake valves.
Further, in the above described first and second embodiments, the solenoid valves
12
which correspond to the intake valves or the exhaust valves provided for the same cylinder are actuated by the same actuating circuits
74
and
174
. However, as described above, it is also practicable that only one of the #1 solenoid valve
12
-
1
and the #2 solenoid valve
12
-
2
is actuated so as to be opened and closed while the other is held closed by means of the same actuating circuits
74
and
174
. Therefore, two valves of which opening periods do not overlap with each other, for example, one intake valve (or exhaust valve) of a first cylinder and one intake valve (or exhaust valve) of a fourth cylinder, or one intake valve (or exhaust valve) of a second cylinder and one intake valve (or exhaust valve) of a third cylinder in an four-cylinder internal combustion engine, may be actuated by the same actuating circuits
74
and
174
.
In the above described first and second embodiments, the #1 FET
80
through the #9 FET
96
, the line terminal
76
and the ground terminal
78
correspond to the switching means described in claims, a first line terminal described in claims and a second line terminal described in claims, respectively.
The present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing from scope of the present invention.
Claims
- 1. In a solenoid valve actuating apparatus for actuating a plurality of engine valves, for each of which provided are a first electromagnet to actuate said engine valve in a first predetermined direction and a second electromagnet to actuate said engine valve in a second predetermined direction, by means of said first and second electromagnets so that a plurality of said engine valves will be opened and closed, said solenoid valve actuating apparatus characterized in that:two of said engine valves form one engine valve group and an actuating circuit is provided for each of said engine valve groups; said actuating circuit comprises three series circuits each comprising three switching means connected in series between a first line terminal on a high voltage side and a second line terminal on a low voltage side; and four of the electromagnets corresponding to each of the engine valve groups connect connecting-in-series portions between said switching means between different series circuits.
- 2. The solenoid valve actuating apparatus as claimed in claim 1, characterized in that:said actuating circuit comprising a first through third series circuits having a first through third switching means connected in series in order from said first line terminal side between said first line terminal and said second line terminal; and said four electromagnets are connected between a connecting portion of the first and the second switching means of said first series circuit and a connecting portion of the first and the second switching means of said second series circuit, between a connecting portion of the second and the third switching means of said first series circuit and a connecting portion of the second and the third switching means of said second series circuit, between the connecting portion of the first and the second switching means of said second series circuit and a connecting portion of the first and the second switching means of said third series circuit, and between the connecting portion of the second and the third switching means of said second series circuit and a connecting portion of the second and the third switching means of said third series circuit, respectively.
- 3. The solenoid valve actuating apparatus as claimed in claim 2, characterized in that:the first electromagnet corresponding to one engine valve of each of the engine valve groups is connected between the connecting portion of the first and the second switching means of said first series circuit and the connecting portion of the first and the second switching means of said second series circuit, and the second electromagnet corresponding to said one engine valve is connected between the connecting portion of the second and the third switching means of said first series circuit and the connecting portion of the second and the third switching means of said second series circuit; and the first electromagnet corresponding to another engine valve is connected between the connecting portion of the second and the third switching means of said second series circuit and the connecting portion of the second and the third switching means of said third series circuit, and the second electromagnet corresponding to said other engine valve is connected between the connecting portion of the first and the second switching means of said second series circuit and the connecting portion of the first and the second switching means of said third series circuit.
- 4. The solenoid valve actuating apparatus as claimed in claim 1, characterized in that each of said switching means includes a switching element turning on and off and a diode disposed in parallel with said switching element so as to allow a current to flow from said second line terminal side to said first line terminal side.
- 5. The solenoid valve actuating apparatus as claimed in claim 1, characterized in supplying each of said electromagnets with an exciting current having a predetermined wave form by switching combinations of an ON state and an OFF state of said switching means.
- 6. The solenoid valve actuating apparatus as claimed in claim 5, characterized in that said predetermined wave form comprises a wave form portion of a positive current in a predetermined positive direction and a wave form portion of a reverse current in a reverse direction to said positive direction.
- 7. In a solenoid valve actuating apparatus for actuating a plurality of engine valves, for each of which provided are a first electromagnet to actuate said engine valve in a first predetermined direction and a second electromagnet to actuate said engine valve in a second predetermined direction, by means of said first and second electromagnets so that a plurality of said engine valves will be opened and closed, said solenoid valve actuating apparatus characterized in that:two of said engine valves form one engine valve group and an actuating circuit is provided for each of said engine valve groups; said actuating circuit comprises: a first and a second series circuits each comprising three switching means connected in series between a first line terminal on a high voltage side and a second line terminal on a low voltage side; and a third series circuit wherein two of the switching means and one diode disposed so as to allow a current flow from said second line terminal side to said first terminal side are connected in series between said first line terminal and said second line terminal so that said diode will be disposed in a center; and four of the electromagnets corresponding to each of the engine valve groups are connected between connecting portions of the switching means and the diode of said third series circuit and connecting portions between the switching means of said first or second series circuit.
- 8. The solenoid valve actuating apparatus as claimed in claim 7, characterized in that:each of said first and second series circuits comprises a first through third switching means connected in series in order from said first line terminal side between said first line terminal and said second line terminal, and said third series circuit comprises a first switching means, the diode provided so as to allow the current flow from said second line terminal side to said first terminal side and a second switching means connected in series in order from the first line terminal side between the first line terminal and the second line terminal; and said four electromagnets are connected between a connecting portion of the first and the second switching means of said first series circuit and a connecting portion of the first switching means and the diode of said third series circuit, between a connecting portion of the second and the third switching means of said first series circuit and a connecting portion of the diode and the second switching means of said third series circuit, between a connecting portion of the first and the second switching means of said second series circuit and the connecting portion of the first switching means and the diode of said third series circuit, and between a connecting portion of the second and the third switching means of said second series circuit and the connecting portion of the diode and the second switching means of said third series circuit, respectively.
- 9. The solenoid valve actuating apparatus as claimed in claim 8, characterized in that:the first electromagnet corresponding to one engine valve of each of the engine valve groups is connected between the connecting portion of the first and the second switching means of said first series circuit and the connecting portion of the first switching means and the diode of said third series circuit, and the second electromagnet corresponding to said one engine valve is connected between the connecting portion of the second and the third switching means of said first series circuit and the connecting portion of the second switching means and the diode of said third series circuit; and the first electromagnet corresponding to another engine valve is connected between the connecting portion of the second and the third switching means of said second series circuit and the connecting portion of the second switching means and the diode of said third series circuit, and the second electromagnet corresponding to said other engine valve is connected between the connecting portion of the first and the second switching means of said second series circuit and the connecting portion of the first switching means and the diode of said third series circuit.
- 10. The solenoid valve actuating apparatus as claimed in claim 7, characterized in that each of said switching means includes a switching element turning on and off and a diode disposed in parallel with said switching element so as to allow a current to flow from said second line terminal side to said first line terminal side.
- 11. The solenoid valve actuating apparatus as claimed in claim 7, characterized in supplying each of said electromagnets with an exciting current having a predetermined wave form by switching combinations of an ON state and an OFF state of said switching means.
Priority Claims (1)
Number |
Date |
Country |
Kind |
9-337402 |
Dec 1997 |
JP |
|
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
102e Date |
371c Date |
PCT/JP98/05528 |
|
WO |
00 |
6/7/2000 |
6/7/2000 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO99/30068 |
6/17/1999 |
WO |
A |
US Referenced Citations (4)
Foreign Referenced Citations (7)
Number |
Date |
Country |
63-277810 |
Nov 1988 |
JP |
63-193706 |
Dec 1988 |
JP |
1-11930 |
Apr 1989 |
JP |
8-284626 |
Oct 1996 |
JP |
9-189209 |
Jul 1997 |
JP |
9-217613 |
Aug 1997 |
JP |
10-47140 |
Feb 1998 |
JP |