JPH10141028A - Electromagnetic valve system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize seating control being control to reduce the generation of an impact when a plunger seats on an electromagnet. SOLUTION: A difference 22a in level is produced at the outer peripheral part of an upper core 22. When a plunger 16 is moved upward due to a difference in a level, a damper chamber 50 is formed between a plunger 16 and an upper core 22. Further, an on-off valve (a check valve) 40 consisting of a magnetic substance ball valve element 42 and a non-magnetic return spring 44 is arranged in an upper core 22. The on-off valve 40 stabilizes seating of the plunger 16 to an upper core 22 and separation of it from the upper core 22 by controlling communication between a passage 52 to the damper chamber 50 and a passage 54 to the space, i.e., the outside, of an upper spring through operation of an electromagnetic force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electromagnetically driven valve mechanism used as an intake / exhaust valve of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as an intake / exhaust valve of an internal combustion engine, a valve that is opened and closed by a camshaft driven based on rotation of a crankshaft is generally used. From the viewpoint of improving the performance of the internal combustion engine, various variable mechanisms of the valve train are being put into practical use in order to achieve the optimal valve opening / closing timing according to the operating state. OF
F-control type) and continuously variable type are also being developed. These variable mechanisms include those that shift the rotation phase of the camshaft and those that have a plurality of cam profiles on the camshaft.

However, in the intake and exhaust valves driven by the camshafts described above, it is impossible to independently and arbitrarily set the valve lift (valve lift), the valve opening period, and the valve opening / closing timing. Therefore, in recent years, in order to meet the demand for higher performance of the internal combustion engine, research on an electromagnetically driven valve train that can set those parameters to ideal values according to the operation state has been activated. I have.

For example, Japanese Patent Application Laid-Open No. 59-213913 discloses that a valve body is elastically supported at a neutral position by a biasing force of a pair of springs, and an electromagnetic force is applied to a plunger connected to the valve body. An electromagnetically driven valve having a structure for moving a valve body from a neutral position to a fully open direction or a fully closed direction is disclosed. As described above, the electromagnetically driven valve constituting the spring-mass system including the plunger as a mass is excellent in that power consumption is small.

In the electromagnetically driven valve constituting the spring mass system, the force acting on the plunger is an electromagnetic force and an urging force of a spring. The electromagnetic force is generated between the plunger and the electromagnet generating the electromagnetic force. As the distance becomes smaller, it increases sharply in comparison with the urging force. Therefore, as is common to other electromagnetically driven valves, control (seating control) for reducing the impact when the plunger is attracted to or seated on the electromagnet is required.

In order to realize this seating control, it is necessary to control the electromagnetic force, that is, to control the current. However, since the electromagnetic force fluctuates greatly due to the fluctuation of the current control, it is extremely difficult to control the seating speed to be constant and stable. That is, achieving stable seating control only by controlling the electromagnetic force in the presence of various disturbances is complicated, and the possibility of realizing the seating control is low.
There are also individual differences. Therefore, the stroke end (s
It is preferable to use an air gap formed at a troke end (a displacement end in a stroke of the plunger) as a damper mechanism (for example, Japanese Patent Laid-Open No. 59-2290).
No. 12).

[0007]

However, in the above-mentioned damper mechanism, since a check valve which is closed by the action of air compression in the air gap is used, the onset of the damper action is generally delayed. And, due to this delay, it is not possible to suppress the seating speed to a stable one.
In that case, the timing at which the plunger is finally attracted to the electromagnet is delayed, and as a result, the period during which only the current necessary to maintain the attracted state needs to be relatively shortened, and power consumption increases. I will.

In view of such circumstances, an object of the present invention is to provide an electromagnetically driven valve mechanism for an internal combustion engine, which stabilizes seating control, which is control for reducing impact when a plunger is seated on an electromagnet. It is in.

[0009]

According to the present invention, a valve body is elastically supported at a neutral position by a spring to form a spring mass system and is integrated with the valve body. An electromagnetically driven valve mechanism of an internal combustion engine in which an electromagnetic force is applied to the plunger and the valve body is displaced from the neutral position to the fully open position or the fully closed position, the damper being formed at a displacement end by the plunger. An on-off valve is provided in a passage communicating the chamber with the outside, and the on-off valve is configured to be closed by a valve body displaced by the action of an electromagnetic force. A drive valve mechanism is provided.

[0010] In the electromagnetically driven valve mechanism of the internal combustion engine configured as described above, the opening / closing valve provided in the passage communicating the damper chamber with the outside is different from the conventional pressure response, and is operated by the action of electromagnetic force. Since the valve closing operation is performed, the communication path is immediately shut off together with the action of the electromagnetic force, and a damper action is developed, so that the displacement speed of the valve body of the intake / exhaust valve can be reduced with a very short stroke. On the other hand, during the return operation of the plunger toward the neutral position, the action of the electromagnetic force is eliminated, and the communication passage is opened so that air can freely flow into the damper chamber. The return operation of the valve body of the exhaust valve is smooth and quick, and there is no resistance to the movement of the plunger. Therefore, power consumption can be reduced.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing an electromagnetically driven valve mechanism according to one embodiment of the present invention. Valve element 1 shown in FIG.
Reference numeral 0 denotes a valve head (also referred to as a valve head) or a valve shaft 14, and a valve face 13 of the valve head 12 is provided with an intake / exhaust port 32 of the internal combustion engine. Valve seat (valve seat: valve sea
t) Opening / closing the intake / exhaust port 32 by sitting on or leaving the valve seat 33. Valve shaft 1 of valve body 10
4 is held by the valve guide 31 so as to be slidable in the axial direction. In addition, a plunger (plung
er) (also called armature) 16 is fixed.

The plunger 16 is a disk-shaped member made of a soft magnetic material. Above the plunger 16, an upper core (upper core) 22 is provided at a predetermined distance, and below the plunger 16, a lower core 23 is similarly provided at a predetermined distance. I have. The upper core 22 and the lower core 23 are made of a soft magnetic material, and a case 20 made of a non-magnetic material.
Are maintained in a predetermined positional relationship. The upper core 22 holds an upper coil 24, and the lower core 23 holds a lower coil.
25 are gripped.

The valve shaft 14 is provided with an upper spring (upp).
er spring) 26 and lower spring 27
Thereby, it is elastically supported in the axial direction. The upper spring 26 and the lower spring 27 are balanced so that the position (neutral position) of the plunger 16 when the power is not supplied to the upper coil 24 and the lower coil 25 is an intermediate position between the upper core 22 and the lower core 23. Have been. When the plunger 16 is at the neutral position, the valve element 10 is set at an intermediate position between the fully open side displacement end and the fully closed side displacement end.

According to this configuration, a magnetic circuit including the upper core 22, the plunger 16, and the air gap formed therebetween is formed around the upper coil 24. Therefore, when a current flows through the upper coil 24, the magnetic flux recirculates in the magnetic circuit, and an electromagnetic force is generated in a direction to reduce the air gap, that is, a direction to displace the plunger 16 upward. On the other hand, a magnetic circuit including the lower core 23, the plunger 16, and an air gap formed therebetween is formed around the lower coil 25. Therefore, when a current flows through the lower coil 25, an electromagnetic force is generated in the direction of displacing the plunger 16 downward from the same principle.

Thus, by alternately passing a current through the upper coil 24 and the lower coil 25, the plunger 16
Can be reciprocated up and down, that is, the valve element 10 can be alternately driven in the opening and closing directions. The engine electronic control unit (ECU) 70 determines the opening and closing timing of the solenoid valve based on signals from various sensors, and controls the energization (power supply) from the battery 72 to the upper coil 24 and the lower coil 25 by the drive circuit 71. Thereby, the solenoid valve is driven.

A plurality of curves shown by solid lines in FIG. 2 indicate the relationship between the position of the plunger 16 (the position in contact with the upper core 22 is zero) and the electromagnetic force (attractive force) exerted on the plunger 16 by the electromagnet related to the upper core 22. Is expressed using a current value flowing through the upper coil 24 as a parameter. As shown by these curves, the electromagnetic force (attraction force) acting on the plunger rapidly increases as the valve body 10 approaches the fully closed side displacement end. On the other hand, a straight line shown by a broken line in FIG. 2 indicates the position of the plunger 16 and the upper spring 26 and the lower spring 27 similarly.
And the relationship with the urging force (lower core 23 side). As can be seen from this straight line, the urging force only increases linearly even when the valve body 10 approaches the fully closed displacement end. The electromagnetic force generated by the electromagnet related to the lower core 23 is also the same as that shown in FIG. 2, and the fully closed position is simply changed to the fully open position. Therefore, as the position approaches the fully open position or the fully closed position, an electromagnetic force exceeding the urging force can be obtained with a smaller current than in the vicinity of the neutral position. Next, a method of driving the electromagnetic valve in consideration of the characteristics of the electromagnetic force and the urging force will be described.

FIG. 3 is a time chart showing the lower coil current (A), the valve lift (B), and the upper coil current (C). In the fully closed state, a minimum necessary current (hereinafter, referred to as a holding current) for flowing the plunger 16 to the upper core 22 by suction is supplied to the upper coil 24 as shown in FIG. When the valve is to be opened, first, the supply of the holding current is stopped. Then, the valve element 10 moves in the fully open direction due to the simple vibration (free vibration) of the spring mass system, but due to the friction loss between the valve shaft 14 and the valve guide 31, the internal friction loss of the spring itself, and the like. Since the amplitude of the valve body 10 attenuates with respect to the ideal state, current is supplied to the lower coil 25 at a certain timing. The current can be divided into three currents, an attraction current, a transition current, and a holding current, as shown in FIG.

That is, first, an attraction current for moving the plunger 16 flows. Next, FIG.
In view of the above characteristics, a transition current that decreases with a certain temporal change rate is passed so that the plunger 16 is attracted in a state where the electromagnetic force (attraction force) is weakened. Then, after the plunger 16 is sucked, a minimum current, that is, a holding current, required for holding the valve body 10 by suction is supplied. Similarly, when trying to close the valve from the fully open state,
The supply of the holding current to the lower coil 25 is stopped, and the supply of the attraction current, the transition current, and the holding current to the upper coil 24 is sequentially performed.

By the way, even if the current control as described above is performed, the plunger 16 is not controlled by the upper core 22 or the lower core 23.
As described above, it is extremely difficult to stabilize the seating control for reducing the impact when being attracted to the vehicle due to individual differences, disturbance, and the like. Therefore, in order to reduce the seating impact, the plunger 16 and the upper core 22 or the lower core 2
3 is used as a damper mechanism. Since this damper mechanism has the same configuration and operation on both the upper side (valve-closed side) and the lower side (valve-opened side), the upper side (valve-closed side) will be described below.

FIG. 4 is a sectional view showing in detail a portion related to the upper-side damper mechanism. As shown in the figure, a step 22 a is provided on the outer peripheral portion of the upper core 22. When the plunger 16 moves upward due to the step, the plunger 16 and the upper core 2
2, a damper chamber 50 is formed. In the upper core 22, an on-off valve (check valve) 40 comprising a magnetic ball valve 42 and a non-magnetic return spring 44 is provided.
Is provided. The on-off valve 40 controls the communication between the passage 52 to the damper chamber 50 and the passage 54 to the space (ie, the outside) of the upper spring 26 as follows. With such an air damper mechanism, the plunger 16
The seating on the upper core 22 and the separation from the upper core 22 are stabilized.

When the plunger 16 moves upward, an electromagnetic force (attraction force) is generated by energizing the upper coil 24 as described above. When the plunger 16 approaches the upper core 22 and the magnetic field saturates, this electromagnetic force overcomes the urging force of the return spring 44 and pushes up the magnetic ball valve 42. as a result,
The entrance to the damper chamber side passage 52 is closed. The air confined in the damper chamber 50 is thus compressed as the plunger 16 moves upward, and as a reaction thereto, a force urging the plunger 16 downward is applied, and as a result, the seating shock is reduced. Note that this force changes according to the size of the step, the clearance between the step portion and the plunger, and the like. By setting the force to be slightly smaller than the electromagnetic force shown in FIG. Stabilize.

Next, in a state where the upper core 22 sucks the plunger 16, that is, in a seated state, the upper coil 2
When the energization of the ball valve 4 is stopped, the electromagnetic force acting on the ball valve 42 disappears, and the ball valve 42 moves downward by the urging force of the return spring 44. Therefore, the passage 54 leading to the space of the upper spring 26 and the passage 52 leading to the damper chamber communicate with each other, and the air flows into the damper chamber 51 as the plunger 16 moves downward. As described above, the force for holding the plunger 16 upward does not work, and the plunger 16 moves smoothly downward.

FIG. 5 is a sectional view showing another embodiment of the upper damper mechanism. As can be seen from the figure, in this embodiment, the on-off valve 40 is provided in the plunger 16. When the plunger 16 moves upward, the damper chamber 50 is formed in the same manner as described above, and the magnetic ball valve body 42 is attracted upward by the electromagnetic force, and as a result, is confined in the damper chamber 50. The air acts as an air damper. Next, when the plunger 16 is opened, the power supply to the upper coil 24 is stopped, and the biasing force of the pair of return springs 44a and 44b moves the ball valve body 42 to the neutral position. As a result, air easily flows into the damper chamber 50, and the plunger 16 separates from the upper core 22 side to the lower side without receiving any resistance.

Although the embodiments of the present invention have been described above, the present invention is of course not limited to these embodiments.

[0026]

As described above, according to the present invention,
In the electromagnetically driven valve mechanism of the internal combustion engine, stabilization of seating control, which is control for reducing impact when the plunger is seated on the electromagnet, is achieved. Further, according to the present invention, even when the plunger separates from the electromagnet, the operation is smoothed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an electromagnetically driven valve mechanism according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram (solid line) representing a relationship between a plunger position and an electromagnetic force (attractive force) exerted on the plunger by the upper electromagnet as a parameter with an upper coil current as a parameter; FIG. 7 is a characteristic diagram (broken line) showing the relationship with the graph.

FIG. 3 is a time chart of a lower coil current (A), a valve lift (B), and an upper coil current (C).

FIG. 4 is a sectional view showing in detail a portion related to an upper-side air damper mechanism.

FIG. 5 is a cross-sectional view showing another embodiment of the upper-side air damper mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Valve element 12 ... Valve head 13 ... Valve face 14 ... Valve shaft 16 ... Plunger 20 ... Case 22 ... Upper core 23 ... Lower core 24 ... Upper coil 25 ... Lower coil 26 ... Upper spring 27 ... Lower spring 31 ... Valve guide 32 ... Internal combustion engine Intake / exhaust ports 33 ... valve seats 40, 41 ... opening / closing valve 42 ... ball valve body 44 ... return springs 44a, 44b ... a pair of return springs 50 ... damper chamber 52 ... damper chamber side passage 54 ... external passage 70 ... engine Electronic control unit 71: drive circuit 72: power supply

Claims (1)

[Claims] 1. A valve body is elastically supported by a spring at a neutral position to form a spring mass system, and an electromagnetic force is applied to a plunger integrated with the valve body so that the valve body is moved to the neutral position. An electromagnetically driven valve mechanism for an internal combustion engine that is displaced from a closed position to a fully open position or a fully closed position, wherein an opening / closing valve is provided in a passage communicating a damper chamber formed by the plunger with the outside at a displacement end; An electromagnetically driven valve mechanism for an internal combustion engine, wherein the valve is configured to be closed by a valve body displaced by the action of an electromagnetic force.