JP2000306724A - Electromagnetic actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the electromagnetic actuator which can be reduced in power consumption. SOLUTION: This electromagnetic actuator 1 is equipped with a yoke 11, which has an inner yoke 12 and an outer yoke 13 across a coil chamber 17, an electromagnet equipped with a coil 16 stored in the coil chamber 17, and an armature 5 which performs driving by reciprocating so that it comes into contact with the yoke 11 by being attracted through the excitation of the electromagnet and leaves the yoke 11 through the interruption of the excitation of the electromagnet. A ratio D/L of a width D and a height L of a coil groove 17 is set to a value larger than a prescribed value, so that the degree of decrease of the overcurrent loss and/or leakage magnetic flux of the electromagnet with the ratio D/L decreases gradually.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electromagnetic actuator for driving a driven body by an electromagnetic force.

[0002]

2. Description of the Related Art Conventionally, as this type of electromagnetic actuator, for example, one described in Japanese Patent Application Laid-Open No. 9-256826 is known. This electromagnetic actuator
It is for opening and closing the intake and exhaust valves of the internal combustion engine, and is composed of a plurality of actuator casings housed in the cylinder head and a magnetic material, and is slidable on sliding paths in each actuator casing. And an armature connected to an intake / exhaust valve and upper and lower electromagnets for vertically sucking the armature. During operation of the electromagnetic actuator, the armature is attracted by the upper and lower electromagnets and reciprocates in the sliding path in the vertical direction, whereby the intake and exhaust valves are opened and closed.

Further, the armature has a cross section in which both ends of two concentric arc portions are connected by two linear portions parallel to each other (see FIG. 6 of the publication), and the inner circumference of the actuator casing is formed. The surface and the outer peripheral surface are formed in a cross section substantially similar to the outer peripheral surface of the armature. Further, the electromagnet includes a yoke composed of an inner yoke and an outer yoke, both of which are made of a magnetic material, and a coil housed between the inner yoke and the outer yoke and wound around the inner yoke. The inner yoke has a cross section substantially similar to the actuator casing, and the outer yoke has a cross section substantially similar to the armature.

In this electromagnetic actuator, two actuator casings each having the above-described cross-sectional shape are arranged so as to be in contact with each other at a plane portion on the outer peripheral surface. With the configuration described above, in this electromagnetic actuator, even when a plurality of actuator casings are arranged and housed in a narrow space in the cylinder head, as large a space as possible in the actuator casing is ensured, so that the largest possible The dimensions of the coil of the electromagnet and the cross section of the armature are obtained. The reason for this is that a very large driving force is required when driving the intake and exhaust valves, so that even when the electromagnetic actuator is housed in a narrow cylinder head, it is not sufficient to drive the intake and exhaust valves. This is to secure the attraction of the armature by the various electromagnets.

[0005]

Generally, in the above-mentioned electromagnetic actuator, the electric energy supplied to the electromagnet during operation is partially affected by copper loss, which is a loss due to coil resistance, or magnetic material. It is consumed as eddy current loss, which is a loss due to eddy currents generated inside, and hysteresis loss, which is a hysteresis characteristic generated inside the magnetic material, and is simply accumulated in all areas near the electromagnet due to leakage magnetic flux etc. Magnetic energy that does not change to, and then is consumed as eddy current loss and copper loss,
Some are regenerated. Further, the remaining electric energy excluding the above is converted into mechanical work for sucking a driven body such as an intake / exhaust valve through the armature. Therefore, if the loss excluding the mechanical work is reduced, the electric energy is effectively converted into the mechanical work, so that the power consumption can be reduced. However, in the above-mentioned conventional electromagnetic actuator, the attraction force of the electromagnet is secured by simply increasing the cross-sectional area of the armature and the dimensions of the coil, so depending on the shape and dimensions of the yoke and the armature, etc. On the other hand, power consumption may increase due to an increase in each loss as described above.

[0006] The present invention has been made to solve the above-mentioned problems, and has as its object to provide an electromagnetic actuator capable of reducing power consumption.

[0007]

The electromagnetic actuator 1 of the first aspect is housed in the coil chamber 17 and the yoke 11 having an inner yoke 12 and an outer yoke 13 defining a coil chamber 17 therebetween. An electromagnet 10 having a coil 16 and a magnetic material are attracted to the yoke 11 by excitation of the electromagnet 10 so that the yoke 1
1 and an armature 5 for driving by reciprocating away from the yoke 11 by stopping the excitation of the electromagnet 10, wherein the coil is an interval between the inner yoke 12 and the outer yoke 13. The width D of the chamber 17 and the distance between the inner surface of the armature 5 and the bottom surface of the coil chamber 17 when the yoke 11 comes into contact with the coil chamber 17 along the direction of reciprocation of the armature 5.
(For example, the aspect ratio D / in the embodiment).
L) is a predetermined value (for example, the value “0.3” in FIG. 6 in the embodiment) in which the degree of decrease in at least one of the eddy current loss and the leakage magnetic flux (aspect ratio D / L) of the electromagnet 10 gradually decreases. It is characterized in that it is set to the above value (value “0.4”).

According to this electromagnetic actuator, the armature is attracted to the electromagnet by the excitation of the electromagnet, comes into contact with the yoke, and reciprocates away from the electromagnet when the excitation is stopped. The term “excitation” includes a state in which the armature is stopped while maintaining a small interval with respect to the yoke by not only mechanical contact but also electrical attraction. "Stop excitation"
Means stop of energization). By the reciprocating motion of the armature, for example, a driven body connected to the armature is driven. When such an electromagnet is excited, the values of the eddy current loss and the leakage flux generated in the electromagnet are generally the ratio of the width and height of the coil chamber, that is, the distance between the inner yoke and the outer yoke, and the yoke. It increases or decreases according to a change in the ratio of the distance between the inner surface of the contacted armature and the bottom surface of the coil chamber along the direction of reciprocation of the armature. More specifically, the eddy current loss and the leakage magnetic flux have a characteristic that they rapidly decrease with a change in the ratio until the above-mentioned ratio reaches a predetermined value, and the degree of decrease gradually decreases when the ratio exceeds a predetermined value. are doing. Therefore, in the present invention, the ratio of the width to the height of the coil chamber is set to a value equal to or more than a predetermined value such that the degree of reduction of the eddy current loss and / or the leakage magnetic flux is gradually reduced. // Leakage magnetic flux can be effectively suppressed. As a result, electric energy at the time of excitation of the electromagnet can be efficiently converted into mechanical work for driving the driven body, and therefore, power consumption can be reduced.

An electromagnetic actuator 1 according to a second aspect of the present invention comprises an electromagnet 10 having a yoke 11 and a coil 16 and a magnetic material. The end of the yoke 11 is attracted to the yoke 11 by excitation of the electromagnet 10. And an armature 5 for driving by being reciprocated away from the yoke 11 by stopping the excitation of the electromagnet 10 while being in contact with and sucking the electromagnet 10. The ends of the yoke 11 and the armature 5 Each is characterized by being narrowed down.

According to this electromagnetic actuator, similarly to the above, the armature reciprocates due to the excitation of the electromagnet and the suspension of the excitation, whereby the driven body is driven. The armature is attracted and held by the yoke when the electromagnet is excited, so that the driven body is attracted and held by the electromagnet. When the electromagnet is excited in the suction holding state, the suction holding force F of the electromagnet when suctioning and holding the armature is generally [F = φ / (2μ0
S)] (where φ is the magnetic flux, μ0 is the magnetic permeability of vacuum, and S is the area of the contact surface (suction surface) of the yoke). Therefore, in the electromagnetic actuator of the present invention, the suction holding force F can be improved by reducing the area S of the contact surface at the end where the armature and the yoke come into contact with each other to such an extent that the magnetic flux φ is not reduced. As a result, compared to an electromagnet that generates the same attractive holding force F, the same attractive holding force F can be generated with a smaller exciting current, so that power consumption can be reduced.

An electromagnetic actuator 1 according to a third aspect of the present invention is composed of an electromagnet 10 having a yoke 11 and a coil 16 and a magnetic material, and is brought into contact with the yoke 11 by being attracted to the yoke 11 by excitation of the electromagnet 10. And an armature 5 for driving by being reciprocated away from the yoke 11 by stopping the excitation of the electromagnet 10 while being attracted and held.
Is the minimum magnetic path area S5, the average magnetic path area S6 of the yoke 11, and the area ratio S5 / S6, and the copper loss held by the electromagnet 10 is the area ratio S.
A predetermined area in the vicinity (for example, the value “0.85 to 0.95” in the embodiment) including a value indicating the minimum value for 5 / S6 (for example, the value “0.9” in FIG. 10 in the embodiment).
(A predetermined area).

According to this electromagnetic actuator, similarly to the above, the armature reciprocates by exciting the electromagnet and stopping the excitation, whereby the driven body is driven. The armature is attracted and held by the yoke when the electromagnet is excited, so that the driven body is attracted and held by the electromagnet. In this case, the area ratio between the minimum magnetic path area of the armature and the average magnetic path area of the yoke is set to a value within a predetermined area in the vicinity thereof, including a value at which the retained copper loss of the electromagnet shows a minimum value at the time of excitation. Since the holding copper loss when the yoke sucks and holds the armature at the time of excitation can be reduced to a minimum value or a value close to the minimum value, a machine for driving the driven body with the electric energy at the time of excitation of the electromagnet is provided. Conversion to work can be efficiently performed, and thus power consumption can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electromagnetic actuator for an internal combustion engine according to a first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, an electromagnetic actuator 1 according to the present embodiment is applied to a valve train of an automobile engine (not shown) that is an internal combustion engine.
Attached to the cylinder head 2 of the engine, and opening and closing an intake port (or exhaust port) (not shown) by driving one intake valve (or exhaust valve) 3 during operation of the engine. It is. The intake valve 3 is a guide cylinder 2 a in the cylinder head 2.
Slidably supported in the vertical direction.

The electromagnetic actuator 1 includes a casing 4
And an armature 5 slidably provided in the casing 4 in the vertical direction, upper and lower electromagnets 10 and 10 for attracting the armature 5 in the vertical direction at the time of excitation, and always attaching the armature 5 downward and upward. And upper and lower coil springs 6 and 6 for urging.

The casing 4 includes upper and lower lids 4a, 4a.
And a case 4 provided between the lids 4a, 4a.
b. As shown in FIG. 4, the outer peripheral surface of the case portion 4b is formed by connecting both ends of two concentric arc portions in parallel with each other.
It has a cross-sectional shape as if it were connected by two straight portions, and these two straight portions constitute a flat portion. The two adjacent electromagnetic actuators 1, 1 are arranged so as to be in contact with each other on the plane portion of the case portion 4b. The inner peripheral surface of the case portion 4b has a cross-sectional shape in which both ends of two arc portions each having a smaller diameter and concentric with the arc portion of the outer peripheral surface are connected by two linear portions parallel to each other. The case portion 4b is built in the inner peripheral surface of the case portion 4b in contact therewith. Although not shown, the upper and lower lids 4a, 4a also have the same cross-sectional shape as the outer peripheral surface of the case 4b, and are disposed vertically so as to face each other with the upper and lower electromagnets 10, 10 and the armature 5 therebetween. Have been.

The upper and lower electromagnets 10, 10 are arranged at a predetermined distance and in the vertical direction at an interval, and define a movable space for the armature 5 therebetween. Upper and lower electromagnets 10, 1
Numeral 0 is vertically symmetrical with the armature 5 interposed. Hereinafter, the configuration of the lower electromagnet 10 will be described. As shown in FIGS. 1 to 3, the lower electromagnet 10 includes a yoke 11
A bobbin 15 fitted to the inner yoke 12 of the yoke 11, and a coil 16 wound on the outer peripheral surface of the bobbin 15.
And

The yoke 11 is formed by integrally connecting an inner yoke 12 and an outer yoke 13 by yoke connecting bolts 14. The inner yoke 12 and the outer yoke 13 are made of a magnetic material such as Fe, for example. Is made of a non-magnetic material such as a synthetic resin. The inner yoke 12 includes a disk-shaped terminal portion 12a and a cylindrical portion 12b extending upward from the terminal portion 12a. Inside the terminal portion 12a and the cylindrical portion 12b, a circular cross-section penetrating in the up-down direction is provided. A hole 12c is formed concentrically with the cylindrical portion 12b.
The upper surface of the cylindrical portion 12b of the inner yoke 12 is a contact surface 12d that comes into contact with the armature 5 when the armature 5 is sucked.

The inner peripheral surface 13a of the outer yoke 13 is formed in a circular cross section concentrically with the cylindrical portion 12b and the hole 12c, and the outer peripheral surface 13b is formed by connecting both ends of two arc portions concentric with the inner peripheral surface circle. It is formed in a cross-sectional shape connected by a straight line extending in the left-right direction in parallel. That is, the thickness of the outer yoke 13 is increased in a direction perpendicular to the direction in which the electromagnetic actuators 1 and 1 are arranged.
As shown in the figure, even when the electromagnetic valve gears 1 and 1 are arranged at a small interval, the outer circumference of the outer yoke 13 is set to be larger than the outer diameter of the armature 5 as compared with the case where the outer yoke is cylindrical. While the outer yoke 1
3, the space of the coil 16 and the cross-sectional area of the inner yoke 12 can be as large as possible. The outer yoke 13 has a bottom wall 13c, and a hole concentric with the inner peripheral surface 13a is formed in the bottom wall 13c.

A male screw (not shown) is formed on the outer peripheral surface of the yoke connecting bolt 14, and a female screw (not shown) which is screwed to the male screw of the yoke connecting bolt 14 is formed below the hole 12 c of the inner yoke 12. I have. The inner yoke 12 and the outer yoke 13 are integrally connected by passing the yoke connecting bolt 14 through the hole of the bottom wall 13 c of the outer yoke 13 from below, and screwing the male screw into the female screw of the inner yoke 12. Between the cylindrical portion 12b of the inner yoke 12 and the outer yoke 13 connected in this manner, a coil chamber 17 having an annular cross section that opens upward is defined.
The bobbin 15 and the coil 16 are housed.

As shown in FIG. 5, the width D of the coil chamber 17 is
Is the distance between the inner yoke 12 and the outer yoke 13, and the height L is the lower surface (inner surface) of the large diameter portion 5 a of the armature 5 and the lower surface of the coil chamber 17 when the armature 5 contacts the yoke 11. And the interval. In the present embodiment, the aspect ratio D / L, which is the ratio of the width D to the height L of the coil chamber 17, is set to “0.4” for the reason described below.

The bobbin 15 is made of a non-magnetic material such as a synthetic resin, is formed in a small-thickness cylindrical shape, and has an upper edge portion which extends horizontally outward to form a rounded corner. ing. The bobbin 15 has its inner hole fitted into the cylindrical portion 12b of the inner yoke 12, and the coil 16 is wound around the outer peripheral surface of the bobbin 15 in the circumferential direction.
As described above, the lower electromagnet 10 is configured, and the upper electromagnet 10 is similarly configured vertically symmetrically.

On the other hand, the armature 5 has a central large-diameter portion 5a formed in a circular cross section, and upper and lower small-diameter portions 5b, 5b protruding vertically from the central portions of the upper and lower surfaces of the large-diameter portion 5a.
And upper and lower concave portions 5c, 5c having a circular cross section formed in the upper and lower small diameter portions 5b, 5b, respectively.
As shown in FIGS. 2 and 5, the outer diameter of the large-diameter portion 5a is formed larger than the inner peripheral surface 13a of the outer yoke 13, so that the armature 5 is formed as described later.
When is attracted to the electromagnet 10, the large-diameter portion 5a contacts the outer yoke 13 at the stippled portion in FIG. The outer diameter of the small-diameter portion 5b is smaller than the outer diameter of the inner yoke 12, and the upper surface 5d of the upper small-diameter portion 5b (or the lower surface 5d of the lower small-diameter portion 5b) faces the inner yoke 12. 5d contact all over.

Further, upper and lower shafts 7, 7 extending in the vertical direction are fixed to the upper and lower small diameter portions 5b, 5b in such a manner that one ends thereof are fitted in the upper and lower concave portions 5c, 5c. The electromagnetic actuator 1 is vertically symmetrical except for a part with an armature 5 interposed therebetween.
First, the upper configuration will be described. The upper shaft 7
It has a circular cross section, and extends through the hole 12c of the inner yoke 12 of the upper electromagnet 10 to the upper spring chamber 4c in the upper lid 4a.

The upper spring chamber 4c houses the upper coil spring 6 and upper and lower spring seats 8a and 8b, and a spring pressure adjusting screw 8c protrudes from above.
The upper and lower ends of the upper coil spring 6 are respectively upper and lower spring seats 8.
The upper spring seat 8a is always in contact with the lower end of the spring pressure adjusting screw 8c from below. Further, the lower spring seat 8b is fixed to the upper end of the upper shaft 7, and with the above configuration, the upper shaft 7
It is constantly urged downward by the upper coil spring 6. Further, a cylindrical upper guide 9 is provided in the upper lid portion 4a, and the upper guide 9 has an inner hole having a circular cross section that penetrates in a vertical direction. The upper shaft 7 has an upper guide 9
Are loosely fitted in the inner holes, and are thereby slidably supported in the vertical direction.

On the other hand, the lower shaft 7 has a circular cross section similarly to the upper shaft 7 and has the inner yoke 1 of the lower electromagnet 10.
Through the second hole 12c, it extends to the lower spring chamber 4c in the lower lid portion 4a. At the lower end of the lower shaft 7, a spring seat 8d is provided.
Is attached to the spring seat 8d.
Are connected at the upper end. The lower coil spring 6 is accommodated in the lower spring chamber 4c. The lower coil spring 6 has a lower end portion abutting from above on a bottom wall of the lower spring chamber 4c and an upper end portion having a spring seat 8d. Abuts from below. With the above configuration, the lower shaft 7 is constantly urged upward by the lower coil spring 6. On the other hand, a lower guide 9 similar to the upper guide 9 is provided on the lower lid portion 4a.
The lower shaft 7 is slidably supported by the lower guide 9 in a vertical direction. As described above, since the upper and lower shafts 7, 7 are urged downward and upward by the upper and lower coil springs 6, 6, respectively, the armature 5 is operated when both the upper and lower electromagnets 10, 10 are not excited. Then, it is held at a neutral position between the electromagnets 10 (not shown).

The operation of the electromagnetic actuator 1 configured as described above will be described.
When the armature 5 is not excited, the armature 5 is moved up and down by the upper and lower coil springs 6, 6.
The intake valve 3 is also located at a position in the middle of opening and closing (not shown). When, for example, the lower electromagnet 10 is excited from this state, the armature 5 is attracted to the lower electromagnet 10 so that the yoke 1 of the lower electromagnet 10 is pressed against the urging force of the lower coil spring 6.
1 moves downward to a position where it comes into contact with 1 (see FIG. 1). At this time, the upper and lower shafts 7, 7 are connected to the upper and lower guides 9, 9, respectively.
Slid downward while being guided by the respective members. The downward movement of the armature 5 causes the intake valve 3 to open the intake port.

Thereafter, when the excitation of the lower electromagnet 10 is stopped, the armature 5 moves upward by the urging force of the lower coil spring 6. Further, when the upper electromagnet 10 is excited at a predetermined timing after the excitation of the lower electromagnet 10 is stopped, the armature 5 is attracted by the upper electromagnet 10 so that the upper armature 5 resists the urging force of the upper coil spring 6 while being pulled up. The electromagnet 10 moves upward to a position where it contacts the yoke 11 (not shown). The upward movement of the armature 5 causes the intake valve 3 to close the intake port. Next, after the excitation of the upper electromagnet 10 is stopped, the lower electromagnet 10 is excited at a predetermined timing, so that the intake valve 3 opens the intake port as described above. By repeatedly performing the above operation, the armature 5 reciprocates vertically between the upper and lower electromagnets 10 and 10 to open and close the intake valve 3.

Next, the electromagnetic actuator 1 is connected to the intake valve 3
The eddy current loss and the leakage flux generated in the electromagnet 10 when the switch is driven to open and close will be described with reference to FIG. This figure shows an example of the result of measuring the eddy current loss (unit: J) and the leakage magnetic flux (unit: Wb) of the electromagnet 10 while changing the aspect ratio D / L of the coil chamber 17 described above.

As shown in the figure, when the value of the aspect ratio D / L is increased, the leakage magnetic flux and the eddy current loss of the electromagnet 10 are reduced, and as described below, they are almost the same as each other. Show characteristics. This is because one of the factors causing the eddy current loss is the generation of leakage magnetic flux. Specifically, in the region where the aspect ratio D / L is between a value close to “0” and a value less than “0.3”, as the aspect ratio D / L increases, the leakage flux and the eddy current loss increase. Shows a characteristic in which the leakage flux and the eddy current loss gradually decrease in a predetermined region where the aspect ratio D / L is "0.3" or more. The degree of decrease is small. That is, it can be seen that if the aspect ratio D / L is set to a value in a predetermined region of “0.3” or more, the leakage magnetic flux and the eddy current loss can be effectively suppressed.

As described above, the electromagnet 10 of the present embodiment
Since the aspect ratio D / L is set to “0.4”, the leakage magnetic flux and the eddy current loss can be effectively suppressed, so that the electric energy when the electromagnet 10 is excited can be reduced.
It can be efficiently converted to mechanical work for driving the intake valve 3. Thereby, the power consumption of the electromagnet 10 can be reduced.

Further, when the armature 5 reciprocates vertically, the upper and lower shafts 7, 7 having a circular cross section slide while being guided by the circular holes of the upper and lower guides 9, 9, respectively. The armature 5 has a flatter section than the armature 5 which slides on the inner surface of the casing.
By reducing the sliding resistance during the reciprocating motion, the mechanical work required for reciprocating the same can be reduced. Thereby, power consumption can be further reduced.

Next, an electromagnetic actuator according to a second embodiment of the present invention will be described. As shown in FIG.
In the electromagnetic actuator 1 of the present embodiment, the distal end of the inner yoke 12 and the distal end of the small-diameter portion 5b of the armature 5 that comes into contact with the inner yoke 12 during suction are smaller than the electromagnetic actuator 1 of the first embodiment. Only the differences are provided, and the others are similarly configured. As shown in the figure, the upper end (end) of the inner yoke 12 of the lower electromagnet 10 is continuously narrowed in the circumferential direction, and the angle of the narrowed outer side is smaller than the inner side. .
The area S1 of the contact surface 12d of the inner yoke 12
Is smaller than the magnetic path area S2 (S1 <S2), which is the cross-sectional area of the unrestricted portion, and the area ratio S1 / S2 is "0.795" for the reason described later.
Is set to The aperture height H of the aperture portion is set to a predetermined value.

The lower end (end) of the lower small-diameter portion 5b of the armature 5 that contacts the upper end of the inner yoke 12 is also continuously narrowed in the circumferential direction, and the area S3 of the contact surface 5d that contacts the contact surface 12d. Is the same as the contact surface 12d (S3 = S
1) It is smaller than the cross-sectional area S4 of the portion that is not squeezed (S3 <S4) As described above, the lower electromagnet 10
The inner yoke 12 and the lower small diameter portion 5b of the armature 5 are configured, and the inner yoke 12 of the upper electromagnet 10 and the upper small diameter portion 5b of the armature 5 are similarly configured.

As described above, the reason why the tip of the inner yoke 12 and the tip of the small diameter portion 5b sucked and held by the inner yoke 12 are narrowed is as follows. Generally, when the electromagnet 10 is excited, the suction holding force F of the electromagnet 10 when the armature 5 is sucked and held is [F = φ / (2μ0S)].
(Where φ is the magnetic flux, μ0 is the magnetic permeability of vacuum, and S is the area of the contact surface of the yoke). Therefore, if the area S1 of the contact surface 12d of the inner yoke 12 and the area S3 of the contact surface 5d of the armature 5 are reduced as described above to such an extent that the magnetic flux φ is not reduced, the suction holding force F is improved.

FIG. 8 shows an example of the result of measuring the holding copper loss (unit: W) of the electromagnet 10 while keeping the suction holding force F the same and changing the area ratio S1 / S2. The three middle curves show the case where the aperture height H of the aperture portion is set to three different predetermined values H1 to H3 (H1>H2> H3). Referring to the figure, the retained copper loss shows a minimum value when the area ratio S1 / S2 is “0.795”, and increases rapidly when the area ratio S1 / S2 is equal to or less than “0.77”, and the area ratio S1 / S2 becomes “ 1 ”
In other words, it shows a characteristic that gradually increases as the degree of contraction of the contact surface 12d decreases.

The relationship between the area ratio S1 / S2 and the retained copper loss can be obtained in the same manner when the drawing height H is any one of the predetermined values H1 to H3, and it can be seen that the relationship does not depend on the drawing height H. As described above, in the electromagnetic actuator 1 of the present embodiment, since the area ratio S1 / S2 is set to “0.795”, the retained copper loss can be minimized. That is, by appropriately narrowing the area S1 of the contact surface 12d to such an extent that the magnetic flux φ does not decrease, the holding copper loss is effectively reduced to a minimum value, so that the suction holding force F can be effectively improved. As a result, compared to an electromagnet that generates the same attractive holding force F, the same attractive holding force F can be generated with a smaller value of the exciting current, so that the power consumption can be effectively reduced. Further, when the suction holding force F may be a certain value, if the area ratio S1 / S2 is set in a range of “0.77 to 0.9”, the holding copper loss includes the minimum value and is close to that. The power consumption can be reduced in the same manner as described above.

Next, an electromagnetic actuator according to a third embodiment of the present invention will be described. As shown in FIG.
The electromagnetic actuator 1 according to the present embodiment has the first
The basic configuration is the same as that of the electromagnetic actuator 1 of the second embodiment, and the minimum magnetic path area S
5 and the average magnetic path area S6 of the yoke 11 in the area ratio S5 / S
6 is set to “0.9” for the reason described below. Note that the minimum magnetic path area S5 of the armature 5 represents the cross-sectional area of a portion connected to the small diameter section 5b of the large diameter section 5a, and the average magnetic path area S6 of the yoke 11 represents the average cross sectional area of the inner yoke 12.

FIG. 10 shows the average magnetic path area S6 of the yoke 11.
Shows an example of the required holding load (unit: N) and the holding copper loss (unit: W) with respect to the area ratio S5 / S6 when the minimum magnetic path area S5 of the armature 5 is changed while keeping the constant. Here, the necessary holding load is a holding load (suction holding force) required for the yoke 11 to hold the armature 5 by suction. As shown in FIG.
When 5 / S6 is "0.9", the minimum value is shown, and the area ratio S
When 5 / S6 is equal to or more than "0.95", the value gradually increases, and when "5 / S6" is equal to or less than "0.85", the value rapidly increases. Further, the required holding load decreases linearly as the area ratio S5 / S6 decreases, that is, as the mass of the armature 5 decreases.

As described above, in the electromagnetic actuator 1 of this embodiment, since the area ratio S5 / S6 is set to "0.9", the retained copper loss can be minimized. As a result, the electric energy is efficiently converted into the suction holding force, so that the power consumption can be effectively reduced. Further, since the area ratio S5 / S6 is set to “0.9” and the mass of the armature 5 is reduced, the required holding load can be reduced. Further, by changing the minimum magnetic path area S5 while keeping the average magnetic path area S6 constant, without changing the planar dimensions of the armature 5,
In other words, without changing the planar dimensions of the electromagnet 10,
The above effects can be obtained. If the suction holding force can be a certain value, the area ratio S5 / S6 is set to “0.8
If it is set to a value within the predetermined range of "5 to 0.95", the retained copper loss can be reduced to a value close to and including the minimum value, and the power consumption can be reduced in the same manner as described above.

In each of the embodiments described above, an example has been described in which the armature 5 is reciprocated by alternately attracting the armature 5 with the upper and lower electromagnets 10, 10. However, the present invention is not limited to this. For example, one using one electromagnet and a coil spring may be used. Also, an example in which the electromagnetic actuator 1 is applied to a valve train of an automobile engine has been described. However, the electromagnetic actuator 1 is not limited to this, and for example, the E
It can be used as a driving device for driving various driven members as well as a valve for opening and closing the GR tube, a fuel injection valve, and the like.

[0041]

As described above, according to the electromagnetic actuator of the present invention, power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an electromagnetic actuator of an internal combustion engine according to a first embodiment of the present invention.

2A is a cross-sectional view of an electromagnet of the electromagnetic actuator of FIG. 1, and FIG. 2B is a plan view of an armature.

FIG. 3 is an exploded perspective view of an armature and an electromagnet.

FIG. 4 is a diagram showing a planar arrangement of an electromagnetic actuator.

FIG. 5 is a sectional view showing dimensions of a width and a height of a coil chamber of the yoke.

FIG. 6 is a graph showing an example of a relationship between a leakage magnetic flux and an eddy current loss of an electromagnet and a ratio of a width and a height of a coil chamber.

FIG. 7 is a cross-sectional view showing a narrowed shape of a tip of an inner yoke and a tip of a small-diameter portion of an armature of an electromagnetic actuator according to a second embodiment of the present invention.

FIG. 8 is a graph showing an example of the relationship between the retained copper loss of the electromagnet and the area ratio S1 / S2.

FIG. 9 is a sectional view showing a relationship between a yoke and an armature of an electromagnetic actuator according to a third embodiment of the present invention.

FIG. 10 is a graph showing an example of a relationship between a required holding load and a holding copper loss of an electromagnet and an area ratio S5 / S6 between a minimum magnetic path area S5 of an armature and an average magnetic path area S6 of a yoke.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electromagnetic actuator 3 Intake valve 5 Armature 10 Electromagnet 11 Yoke 12 Inner yoke 13 Outer yoke 16 Coil 17 Coil room D Coil room width L Coil room height D / L Aspect ratio (ratio) S5 Minimum magnetic path area of armature S6 Average magnetic path area of yoke S5 / S6 Area ratio

Claims (3)

[Claims] 1. An electromagnet comprising: a yoke having an inner yoke and an outer yoke defining a coil chamber between each other; an electromagnet including a coil housed in the coil chamber; Armature for driving by being reciprocated away from the yoke by stopping the excitation of the electromagnet while being brought into contact with the yoke by being attracted to the yoke by the inner yoke and the armature. The width of the coil chamber, which is the distance between outer yokes, and the coil, which is the distance along the direction of reciprocation of the armature between the inner surface of the armature and the bottom surface of the coil chamber when contacting the yoke. The ratio between the chamber height and the eddy current loss and / or the leakage flux of the electromagnet is reduced with respect to the ratio. Electromagnetic actuator, characterized in that it is set to a predetermined value or more values, such as gradually decreases. 2. An electromagnet having a yoke and a coil, comprising: a magnetic material; and being attracted to the yoke by excitation of the electromagnet, an end of the electromagnet comes into contact with an end of the yoke and is attracted and held. An armature for driving by reciprocating away from the yoke by stopping excitation of the electromagnet, wherein the ends of the yoke and the armature are respectively narrowed. Type actuator. 3. An electromagnet having a yoke and a coil, which is made of a magnetic material, is attracted to the yoke by excitation of the electromagnet, and is brought into contact with the yoke and is attracted and held. An armature for driving by reciprocating away from the yoke by stopping, an area ratio between a minimum magnetic path area of the armature and an average magnetic path area of the yoke is equal to a holding copper of the electromagnet. An electromagnetic actuator characterized in that the loss is set to a value in a predetermined area near the area including a value indicating a minimum value with respect to the area ratio.