JPH09133010A - Solenoid-operated valve driving gear for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize both saving of power and improving of responsiveness, relating to a solenoid-operated valve driving gear for an internal combustion engine driving a valve unit constituting an intake/exhaust valve of the internal combustion engine by electromagnetic force. SOLUTION: A magnetic material-made plunger 30 is fixed to a valve unit 12 of an internal combustion engine through a pop-magnetic material-made plunger holder 18. An electromagnet comprising a first electromagnetic coil 32 and a first core 34 and an electromagnet comprising a second electromagnetic coil 36 and a second core 38 are arranged in the upper/lower of the plunger 30. A contact part into contact before the plunger 30 is brought into contact with the second core 38, in the case of attracting the plunger 30 to the second core 38, is provided in the plunger holder 18 and tire second core 38. An air gap is formed between the plunger 30 and the second core 38, a condition profitable for demagnitizing residual magnetism is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic valve driving device for an internal combustion engine, and more particularly to an electromagnetic valve driving device for an internal combustion engine, which drives a valve element constituting an intake / exhaust valve of the internal combustion engine with an electromagnetic force.

[0002]

2. Description of the Related Art Conventionally, there has been known an electromagnetic valve drive device for an internal combustion engine which drives a valve element such as an intake and exhaust valve of the internal combustion engine by an electromagnetic force generated by an electromagnetic coil. According to this device, the cam mechanism for driving the valve body, which is generally required in the internal combustion engine, is not required, and the opening / closing valve timing of the valve body can be arbitrarily changed, so that the operating state of the internal combustion engine can be adjusted. It is possible to realize an ideal opening / closing valve timing.

As such a valve drive device, a configuration disclosed in, for example, Japanese Patent Laid-Open No. 61-237810 is known. The valve drive device includes a plunger fixed to a valve shaft of an intake / exhaust valve of an internal combustion engine, and electromagnetic coils arranged above and below the plunger. The above plunger is
It is a plate-shaped member made of a soft magnetic material. A core is arranged on the outer circumference of the electromagnetic coil so as to face the plunger.

In the above valve drive device, when a current is supplied to one of the electromagnetic coils, an electromagnetic attractive force acts between the core surrounding the coil and the plunger. As a result, the valve body, until the core and the plunger come into contact with each other,
It is displaced toward the electromagnetic coil to which current is being supplied. From the above state, when the current to one electromagnetic coil is cut off, and the supply of the current to the other electromagnetic coil is started,
The valve body is displaced to the other electromagnetic coil side, and the core surrounding the electromagnetic coil and the plunger come into contact with each other. Therefore, if the electric current is alternately supplied to the electromagnetic coils arranged above and below the plunger, the valve body can reciprocate along its valve axis, and functions as an intake / exhaust valve of the internal combustion engine. Can be realized.

[0005]

In order to efficiently generate an electromagnetic attraction force between the plunger and the core, it is preferable to concentrate the magnetic flux around the portion where the plunger and the core are close to each other. However, as described above, the above-mentioned conventional valve drive device uses the flat plate-shaped plunger made of the soft magnetic material. When such a plunger is used, the magnetic flux generated from the core also flows to a part that is not necessarily required to enhance the electromagnetic attraction between the plunger and the core, specifically, the vicinity of the fixed part between the plunger and the valve shaft. To do. In this respect, the conventional valve drive device described above has a disadvantageous structure in efficiently securing the required electromagnetic attraction force.

Further, in the above-mentioned valve drive device, in order to ensure excellent responsiveness, after interrupting the current to one of the electromagnetic coils, the magnetic circuit surrounding the coil, that is, corresponding to the coil It is desirable that the magnetic flux flowing in the magnetic circuit including the provided core and the plunger attracted to the core be quickly demagnetized. When the current flowing through the electromagnetic coil is cut off, a counter electromotive force is generated in the electromagnetic coil in a direction that prevents the current from decreasing. The counter electromotive force causes a magnetic field to remain around the electromagnetic coil after the supply of current to the electromagnetic coil is cut off. Therefore, in order to secure excellent responsiveness in the above-mentioned electromagnetic coil, it is necessary to quickly extinguish the residual magnetic field caused by the back electromotive force.

It is known that the larger the magnetic resistance of the magnetic circuit through which the residual magnetic field flows is, the more advantageous it is to quickly extinguish the residual magnetic field caused by the back electromotive force. Therefore, in order to quickly eliminate the residual magnetism in the above valve drive device, it is advantageous to increase the magnetic resistance of the magnetic circuit including the plunger and the core while the plunger is attracted to the core. On the other hand, in the electromagnetic valve drive device that drives the valve body by attracting the plunger with the electromagnetic attraction force, when the plunger and the core are relatively separated from each other, a large electromagnetic attraction force is efficiently generated between them. Need to work. From this point of view, the smaller the magnetic resistance of the plunger itself and the core itself, the better.

The above-mentioned two requirements can be realized by suppressing the magnetic resistance of the plunger itself and the core itself to be small, and by making the plunger and the core do not come into direct contact with each other when the plunger is attracted to the core. You can On the other hand, in the above-mentioned conventional valve drive device, the plunger sucked by the core is in a close contact with the core. In this respect, the above-mentioned conventional device has a disadvantageous structure in ensuring excellent responsiveness in the valve drive device.

The present invention has been made in view of the above points, and has a structure that can efficiently secure a necessary electromagnetic attraction force with a simple structure and an excellent responsiveness in a valve drive device. An object of the present invention is to provide an electromagnetic valve drive device for an internal combustion engine that realizes both the structure and the structure.

[0010]

The above object is achieved by the present invention.
In an electromagnetic valve drive device for an internal combustion engine, comprising: a plunger fixed to a valve shaft that supports a valve body of the internal combustion engine; and an electromagnet that generates an electromagnetic force that attracts the plunger. A member for fixing the valve shaft, the plunger holder having a characteristic that magnetic flux is less likely to flow than the plunger, and the plunger holder and the electromagnet are provided, and when the plunger is attracted to the electromagnet This is achieved by an electromagnetic valve drive device for an internal combustion engine, which is in an abutting state and includes an abutting portion that forms a predetermined gap between the plunger and the electromagnet.

In the invention according to claim 1, the valve element is supported by the valve shaft. A plunger is fixed to the valve shaft via a plunger holder. When the electromagnet generates an electromagnetic force, the magnetic flux generated from the electromagnet circulates in the plunger, and an attractive force acts between the electromagnet and the plunger. As a result, the plunger is displaced toward the electromagnet,
A displacement in a predetermined direction is applied to the valve body. The plunger holder has a characteristic that it is more difficult for the magnetic flux to flow than the plunger. For this reason, the magnetic flux generated from the electromagnet is unlikely to flow out to the plunger holder side, and is concentrated on the portion where the plunger and the electromagnet face each other. As a result, the magnetomotive force of the electromagnet is efficiently converted into the attraction force for the plunger. The contact portions provided on the plunger holder and the electromagnet prevent the electromagnet and the plunger from coming into close contact with each other. Since it is difficult for the plunger holder to pass the magnetic flux, the contact state between the plunger holder and the electromagnet does not significantly affect the magnetic resistance of the magnetic circuit including the electromagnet and the plunger. On the other hand, the contact state between the plunger and the electromagnet greatly affects the magnetic resistance. That is, when a gap is formed between the plunger and the electromagnet as in the present invention, a large magnetic resistance is generated in the magnetic circuit including the electromagnet and the plunger, as compared with the case where the plunger and the electromagnet are in close contact with each other. It is formed. When the magnetic resistance of the magnetic circuit including the electromagnet and the plunger is large, the magnetism generated by the electromagnet is quickly demagnetized after the power supply to the electromagnet is cut off.

According to a second aspect of the present invention, in the electromagnetic valve drive system for an internal combustion engine according to the first aspect, the plunger holder has a hardness higher than that of the plunger. The electromagnetic valve drive device is effective in improving the durability of the valve drive device.

In the present invention, the contact / separation of the plunger holder and the electromagnet is repeated during the operation of the electromagnetic valve drive device. Therefore, in order to improve the durability of the electromagnetic valve drive device, it is preferable to impart high hardness to the plunger holder. On the other hand, during operation of the solenoid valve drive, a gap is formed between the plunger and the electromagnet,
The plunger is required to have high magnetism in preference to hardness. In the present invention, since the plunger and the plunger holder are separate members, the hardness of both can be easily made different. When the plunger holder is provided with a hardness higher than that of the plunger, it is possible to provide the plunger holder with high wear resistance while imparting high magnetism to the plunger holder.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an overall configuration of a valve drive system 10 for an internal combustion engine which is an embodiment of the present invention. In the figure, the valve body 12 is a member that is arranged in the cylinder head with its lower end exposed in the combustion chamber of the internal combustion engine and constitutes an intake valve or an exhaust valve of the internal combustion engine. That is, the cylinder head of the internal combustion engine is provided with a port having a valve seat for the valve body 12, and the opening and closing of the port is controlled by the valve body 12 moving away from or seating on the valve seat.

A valve shaft 14 is fixed to the valve body 12. The valve shaft 14 is held by a valve guide 16 so as to be slidable in the axial direction. The valve guide 16 is supported by the lower cap 17 of the valve drive device 10. Valve shaft 14
A plunger holder 18 is fixed to the upper part of the.
The plunger holder 18 is a member made of a non-magnetic material or a material having a low magnetic specificity, and is a cylindrical portion 18a extending in the axial direction of the valve shaft 14 and a ring formed substantially in the axial central portion of the cylindrical portion 18a. And a portion 18b. In this embodiment, a non-magnetic material such as stainless steel or titanium alloy is used as the material of the plunger holder 18 in order to impart high hardness to the plunger holder 18.

A lower retainer 20 is fixed to the lower end of the plunger holder 18. A lower spring 22 is disposed between the lower retainer 20 and the lower cap 17 to generate an urging force in a direction to separate the lower retainer 20 and the lower cap 17.
On the other hand, an upper retainer 24 is fixed to the upper end of the plunger holder 18. Further, the lower end portion of the upper spring 26 is in contact with the upper portion of the upper retainer. A cylindrical upper cap 27 is provided around the upper spring 26 so as to surround the outer periphery thereof. Further, the upper end of the upper spring 26 is in contact with an adjustment bolt 28 screwed to the upper cap 27. In the above configuration, the lower spring 22 generates a biasing force that biases the lower retainer 20, that is, the plunger holder 18 upward in FIG. On the other hand, the upper spring 26 is provided with the upper retainer 24, that is, the plunger holder 1
A biasing force that biases 8 downward in FIG. 1 is generated.

The ring portion 18b of the plunger holder 18
A plunger 30 is joined to the outer periphery of the. The plunger 30 is a doughnut-shaped member made of a soft magnetic material having Fe, Ni, Co or the like as a base material. The plunger 30 and the plunger holder 18 are joined by a method such as electron beam welding, laser welding, brazing, caulking, or bonding.

As shown in FIG. 1, the plunger 30 has a plate thickness of an inner peripheral side end portion 30a joined to the plunger holder 18 and a plate of an outermost peripheral portion (hereinafter referred to as outer peripheral side end portion) 30b of the plunger 30. The thickness is formed to be thinner than the plate thickness of the intermediate portion 30c between the inner peripheral side end 30a and the outer peripheral side end 30b. Therefore, the plunger 30
The intermediate portion 30c has a higher magnetic flux circulation capacity than the inner peripheral side end 30a and the outer peripheral side end 30b.

A first electromagnetic coil 32 and a first core 34 are arranged above the plunger 30. A second electromagnetic coil 36 and a second core 38 are arranged below the plunger 30. The first core 34 and the second core 38 are both members made of a magnetic material, and have annular grooves 34a and 38a for accommodating the first electromagnetic coil 32 or the second electromagnetic coil 36, respectively, and the plunger holder 18. Through holes 34b and 38b for slidably holding the cylindrical portion 18a.

An outer cylinder 40 is arranged around the outer circumferences of the first core 34 and the second core 38. A state in which the first core 34 and the second core 38 hold the first electromagnetic coil 32 and the second electromagnetic coil 36 in the annular grooves 34a, 38a, and hold the plunger holder 18 in the through holes 34b, 38b. Thus, the outer cylinder 40 maintains the predetermined positional relationship.

In the present embodiment, in the first core 34, the second core 38, and the plunger 30, the inner peripheral side end portion 30a of the plunger 30 has the annular grooves 34a, 38a of the first core 34 and the second core 38. The outer peripheral side end 30b of the plunger 30 faces the inner peripheral side, and
4 and the annular grooves 34a and 38a of the second core 34 are designed to face the outer peripheral side. Furthermore, the first core 34
The taper surfaces 34c, 34d; 38c, 38 are provided on the outer peripheral side end and the inner peripheral side end of the second core 38, respectively.
d is formed.

The upper cap 27 described above is fixed to the upper end surface of the first core 34. The lower cap 17 described above is fixed to the lower end surface of the second core 38. The adjuster bolt 28 described above includes the plunger 30.
The neutral position of is adjusted to be the midpoint between the first core 34 and the second core 38.

In the valve drive device 10 having the above structure, the first
When a current is passed through the electromagnetic coil 32 to generate a magnetic field that circulates on the inner peripheral side and the outer peripheral side thereof, the first core 34, the plunger 30, and the air gap between the first core 34 and the plunger 30 are included. Magnetic flux flows through the magnetic circuit. Such a magnetic flux generates an attractive force that attracts the plunger 30 toward the first core 34, that is, an attractive force that displaces the valve body 12 upward in FIG. On the other hand, the second electromagnetic coil 3
When a current is circulated in 6 to generate a magnetic field that circulates on the inner and outer peripheral sides thereof, the second core 38 and the plunger 3
The magnetic flux flows through the magnetic circuit including 0 and the air gap between the second core 38 and the plunger 30. The magnetic flux generates an attractive force that attracts the plunger 30 toward the second core 38 side, that is, an attractive force that displaces the valve body 12 downward in FIG. 1. Therefore, if current is alternately supplied to the first electromagnetic coil 32 and the second electromagnetic coil 36, the plunger 30 reciprocates in the vertical direction, that is, the valve body 12 reciprocates vertically in FIG. Is possible.

When the number of turns of the first electromagnetic coil 32 and the second electromagnetic coil 36 is N, the magnetomotive force Ψ when the current I is supplied to them can be expressed by Ψ = N · I. In order to drive the valve drive device 10 efficiently, the magnetomotive force Ψ = N
It is desirable that a large magnetic flux Φ be generated with respect to I, and that the generated magnetic flux Φ be concentrated in the vicinity of the plunger 30 and the first or second core 34, 38.

In the valve drive device 10 of this embodiment, the first
Alternatively, the magnetic flux generated from the second cores 34, 38 is generated in the vicinity of the inner peripheral side end 30 a of the plunger 30 or in the outer peripheral side end 30.
The first core 3 flows in from near b, passes through the intermediate portion 30c, and approaches the outer peripheral side end 30b or the inner peripheral side end 30a.
4 or to the second core 38. In this case, in the intermediate portion 30c of the plunger 30, all the magnetic flux that has flowed in from a relatively wide area near the inner peripheral side end 30a or the outer peripheral side end 30b flows, so a high magnetic flux circulating ability is required. In the present embodiment, as described above, by forming the plate thickness of the intermediate portion 30c of the plunger 30 to be thicker than other portions, the weight increase of the plunger 30 is suppressed to the minimum, and the intermediate portion 30c is formed. It has a high magnetic flux distribution capability. When the plunger 30 has a high magnetic flux distribution capability in the intermediate portion 30c, the magnetic resistance of the magnetic circuit surrounding the first or second electromagnetic coil 32, 36 is suppressed,
A large magnetic flux Φ can be generated for a magnetomotive force Ψ = N · I.

As described above, the valve drive device 10 is provided with the plunger holder 18 made of a non-magnetic material on the inner peripheral side of the plunger 30. If the inner peripheral side of the plunger 30 is a magnetic member, the first or second core 34, 3
A part of the magnetic flux generated from 8 flows out to the inner peripheral side of the plunger 30, that is, to the cylindrical portion 18a side of the plunger holder 18 in FIG. On the contrary,
According to the configuration of this embodiment, the first or second core 34, 38
The magnetic flux generated from the plunger 30 does not flow out to the inner peripheral side of the plunger 30, and the magnetic flux is effectively absorbed by the plunger 30 and the first
Alternatively, the second cores 34 and 38 can be concentrated in a portion facing each other.

Further, in this embodiment, as described above,
The first and second cores 34, 38 have tapered surfaces 34c, 34
d; 38c and 38d are provided. These taper surfaces 34c, 34d; 38c, 38d allow the magnetic flux generated by the first or second electromagnetic coil 32, 36 to move to the side surface of the inner peripheral side end 30a of the plunger 30 or the outer peripheral side end 30b of the plunger 30. Of preventing inflow or outflow from the side surface of the first core, that is, the first or second core 34, 38
This has the effect of effectively concentrating the magnetic flux generated from the magnetic field at the portion where the plunger 30 and the first or second core 34, 38 face each other.

As described above, the valve drive device 10 of this embodiment.
Is excellent in generating a large magnetic flux Φ with respect to the magnetomotive force Ψ = N · I and concentrating the generated magnetic flux Φ in the vicinity of the plunger 30 and the first or second core 34, 38. Have an effect. Therefore, the valve drive device 1
According to 0, the valve body 12 can be efficiently driven with low power consumption.

By the way, in order to obtain excellent responsiveness in the valve drive device 10, the first or second electromagnetic coil 3 is used.
After the current is cut off from the state where the current is being supplied to the second and the second cores 36, the first or second core 34, 38 and the plunger 3
It is desirable that the magnetic flux flowing in the magnetic circuit including 0 and 0 be quickly demagnetized. In order to quickly demagnetize such residual magnetism, the plunger 30 is provided with the first or second core 34,
It is known that the larger the magnetic resistance formed when adsorbed on 38, the more advantageous.

As described above, in order to obtain the smooth operability of the valve drive device 10, the smaller the magnetic resistance of the magnetic circuit including the plunger 30 and the first or second core 34, 38, the more advantageous it is. Therefore, in order to obtain excellent demagnetization without impairing the smooth operability of the valve drive device 10, the magnetic resistance of the plunger 30 itself, the magnetic resistance of the first core 34 itself, and the magnetic resistance of the second core 38 itself. While the resistance is suppressed to a small level, the plunger 30 can prevent the first or second core 34, 38 from moving.
It is necessary to allow a relatively large magnetic resistance to remain when being adsorbed on the.

The above-mentioned requirement is that when the plunger 30 is attracted to the first or second core 34, 38, between the plunger 30 and the first or second electromagnetic coil 32, 36,
It can be filled by ensuring an appropriate gap.
Such a gap is realized by, for example, forming a nonmagnetic film such as chrome plating on the surface of the plunger 30 or the first and second cores 34 and 38, or fixing a spacer to the plunger 30. be able to. However, these measures reduce productivity,
There are various problems such as an increase in cost and an increase in the number of parts.

The valve drive device 10 of this embodiment is characterized in that a gap is secured between the plunger 30 and the first and second cores 34, 38 without using chrome plating or spacers. doing. Hereinafter, the structure of the characteristic portion will be described with reference to FIG.

FIG. 2 is an enlarged view of the valve drive device 10 and its periphery around the second electromagnetic coil 36. FIG. 2 shows the second electromagnetic coil 3
6 shows a state where the current is supplied to 6 and the plunger 30 is attracted to the second core 38. In the present embodiment, the second core 38 has a contact surface 42 that contacts the ring portion 18b of the plunger holder 18 near the tapered surface 38d. When the plunger 30 is sucked by the second core 38, before the plunger 30 abuts on the second core 38,
The ring portion 18b of the plunger holder 18 and the second core 38
And the contact portion 42 of the contact state. Therefore, a predetermined air gap AG is formed between the plunger 30 and the second core 38.

As described above, the plunger 30 has the second core 3
When the air gap AG is formed between the plunger 30 and the second core 38 when the second electromagnetic coil 36 is adsorbed by the second electromagnetic coil 36, the second electromagnetic coil 36 is cut off after the current of the second electromagnetic coil 36 is cut off.
The residual magnetism due to the counter electromotive force can be quickly eliminated. If the residual magnetism is quickly demagnetized after the current to the second electromagnetic coil 36 is cut off, the plunger 30
Can initiate displacement towards a neutral position with excellent responsiveness. Therefore, according to the valve drive device 10, the valve body 12 can be driven with excellent responsiveness.

By the way, the valve body 12 is a valve body for opening and closing the port provided in the cylinder head as described above. The valve body 12 is separated from the valve seat when the plunger 30 is attracted to the second coil 38 side to open the port, and is opened to the valve seat when the plunger 30 is attracted to the first coil 34 side. Sit down and close the port. The valve-opening side displacement end of the valve body 12 is set to the position where the ring portion 18b of the plunger holder 18 contacts the second core 38 as described above. On the other hand, the valve closing side displacement end of the valve body 12 is set at a position where the valve body 12 is seated on the valve seat.

In the valve drive device 10, the plunger 30 is the first
When sucked toward the core 34 side, the valve body 12 reaches the valve closing side displacement end before the plunger 30 contacts the first core 34. Therefore, the valve drive device 10
In the above, even when the plunger 30 is attracted to the first core 34, a predetermined air gap is secured between the plunger 30 and the first core 34. Therefore, according to the valve drive device 10, the valve body 12 is provided with excellent responsiveness not only after the current to the second electromagnetic coil 36 is cut off but also after the current to the first electromagnetic coil 32 is cut off. Can be driven.

In the above embodiment, the second electromagnetic coil 36 and the second core 38 are the electromagnet according to the first aspect, and the contact portion 42 of the second core 38 and the ring of the plunger holder 18 are the same. A part of the portion 18b is the above-mentioned claim 1.
They correspond to the contact portions described.

By the way, in the above embodiment, the second
Although the core 38 is configured to contact only the ring portion 18b of the plunger holder 18 and not the plunger 30, the present invention is not limited to this. That is, when the plunger 30 is sucked by the second core 38, the two cores may not come into close contact with each other. Further, although the plunger holder 18 is made of a non-magnetic material in the above embodiment, the present invention is not limited to this. That is, the plunger holder 18
Need only have a characteristic that magnetic flux is less likely to flow than the plunger 30.

[0039]

As described above, according to the first aspect of the present invention, the magnetic flux generated from the electromagnet can be concentrated on the opposing portion of the plunger and the electromagnet, and the plunger is attracted to the electromagnet. Moreover, it is possible to reliably form a predetermined gap between the electromagnet and the plunger. With this configuration, the magnetomotive force of the electromagnet can be efficiently converted into a force for driving the valve body, and at the same time, excellent demagnetization can be imparted to the electromagnet. Therefore, according to the electromagnetic valve drive device for an internal combustion engine according to the present invention, both excellent power saving and excellent responsiveness can be obtained.

According to the second aspect of the invention, it is possible to impart high wear resistance to the plunger holder while imparting high magnetism to the plunger. Therefore, according to the structure of the present invention, it is possible to enhance the durability of the electromagnetic valve driving device without impairing the driving efficiency thereof.

[Brief description of the drawings]

FIG. 1 is a front cross-sectional view showing the overall configuration of a valve drive device that is an embodiment of the present invention.

FIG. 2 is an enlarged view showing a configuration of a main part of the valve drive device of the present embodiment.

[Explanation of symbols]

 10 valve drive device 12 valve body 14 valve shaft 18 plunger holder 18a cylindrical portion 18b ring portion 30 plunger 30a inner peripheral side end portion 30b outer peripheral side end portion 30c intermediate portion 32 first electromagnetic coil 34 first core 36 second electromagnetic coil 38 Second core

Claims (2)

[Claims] 1. An electromagnetic valve drive device for an internal combustion engine, comprising: a plunger fixed to a valve shaft that supports a valve body of the internal combustion engine; and an electromagnet that generates an electromagnetic force that attracts the plunger. A member for fixing the valve shaft,
A plunger holder having a characteristic that magnetic flux is less likely to flow than the plunger, and the plunger holder and the electromagnet, which are in contact with each other when the plunger is attracted to the electromagnet, the plunger and the electromagnet An electromagnetic valve drive device for an internal combustion engine, comprising: an abutting part that forms a predetermined gap between the two. 2. The electromagnetic valve drive system for an internal combustion engine according to claim 1, wherein the plunger holder has a hardness higher than that of the plunger. apparatus.