JPH0648648B2 - Electromagnetic actuator - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic actuator which has a permanent magnet in a magnetic circuit and is driven by instantaneous power supply from an external power source when it should be operated.

Conventional technology Conventionally, in order to avoid heat generation in the electromagnetic coil and to save power on the drive circuit side, a permanent magnet is used, the electromagnetic coil is used only for momentary excitation, and the state is maintained by the permanent magnet. An electromagnetic actuator is used. In recent years, in particular, not only AC power sources but also dry batteries have been increasingly used as driving power sources.Therefore, there are restrictions on the voltage conditions applied to the electromagnetic actuator due to the temperature characteristics and load resistance characteristics of the power source batteries. Come on. Therefore, it becomes necessary to keep the operating voltage of the self-holding solenoid within a certain range corresponding to the power supply. In contrast, the accuracy of the magnetic characteristics of the materials of the components of the electromagnetic actuator and the dimensional accuracy of the components have been increased to suppress variations in the voltage required for their operation, but they are still required. Since it is difficult to keep it within a certain range, various operating voltage adjusting methods have been adopted.

An example of the above-mentioned conventional electromagnetic actuator will be described below with reference to the drawings.

FIG. 5 schematically shows the structure of the conventional example. In FIG. 5, the permanent magnet 1 is magnetized in the thickness direction and has a through hole 1a provided in that direction. A fixed adsorbent 2 made of a magnetic material is provided on the movable iron core 3 made of a magnetic material so that the movable iron core 3 can be adsorbed and desorbed on the adsorbing surface 4. A magnetic circuit 6 of the permanent magnet 1 is formed by the first fixed yoke 5a and the second fixed yoke 5b made of magnetic material, the permanent magnet 1, the fixed attracting body 2, and the movable iron core 3, and the movable iron core 3 is fixed. The adsorption surface 4 is adsorbed and held on the adsorbent 2.

The driving electromagnetic coil 7 guides the center of the movable iron core 3 so that the movable iron core 3 slides up and down, and excites the magnetic circuit 6. A female screw portion is provided at a position of the second fixed yoke 5b corresponding to the through hole 1a of the permanent magnet 1, and an adjusting iron core 8 made of a magnetic material and having a female screw portion at that portion is provided with a through hole 1a. It is screwed in to penetrate,
The structure is such that the gap l with the fixed adsorbent 2 can be changed. An adjusting magnetic circuit 9 that does not include the movable iron core 3 is formed between the permanent magnet 1, the second fixed yoke 5b, the adjusting iron core 8, and the fixed attracting body 2. A spring holder 1 is attached to the tip of the movable iron core 3.
0 is mounted, and a compression spring 11 is provided between the fixed spring 5 and the first fixed yoke 5a.

The operation of the electromagnetic actuator configured as described above will be described below.

As a basic operation principle, a voltage is momentarily applied to the electromagnetic coil 7 by a driving power source from the outside so that a magnetic field in a direction opposite to the magnetic field direction of the magnetic circuit 6 is generated. The adsorbing and holding force between the movable iron core 3 and the fixed adsorbing body 2 is weakened, and the compression spring 1 is known for its adsorbing and holding force.
The repulsive force of 1 pushes the movable iron core 3 away from the suction surface 4. On the contrary, although not shown in the figure, when the movable iron core 3 is pushed up, the electromagnetic coil 7
By applying a voltage that generates a magnetic field in the same direction as that of the permanent magnet 1, it is possible to overcome the repulsive force of the compression spring 11 and return the movable iron core 3 to the adsorption holding position again.

Here, when the suction holding force in the suction holding state between the movable iron core 3 and the fixed suction body 2 is F and the repulsive force of the compression spring 11 is f, the movable iron core 3 is pushed up, that is, when it is operated. Assuming that the required voltage to be applied to the electromagnetic coil 7 is the operating voltage V, the value of the operating voltage V is determined depending on the difference (F−f) value between F and f, as can be understood from the operating principle. That is, when the suction holding force F is large or the repulsion force f is small, the operating voltage V is large, and conversely, when F is small or f is large, V is small. Further, when the movable iron core 3 is separated from the attraction surface 4, the larger the repulsive force f of the compression spring 11, the larger the operating voltage V for re-adsorption. Therefore, the strength of the compression spring 11 has an opposite effect on the operating voltage V when it is separated and when it is attracted.

Here, the magnetic flux Φ ₁ due to the permanent magnet 1 passing through the magnetic circuit 6 is generated by the movable iron core 3, the first fixed yoke 5a, which constitute the magnetic circuit 6,
It is greatly affected by variations in magnetic permeability of the second fixed yoke 5b, fixed adsorbent 2 and the like, that is, magnetic characteristics, surface roughness of the adsorbing surface 4, and magnetic characteristics of the permanent magnet 1 itself.
On the other hand, the adsorption holding force F is determined in a form proportional to the magnetic flux Φ ₁ .

This means that even if the electromagnetic actuators are assembled and manufactured with the same structure, the suction holding force F varies greatly for each individual object due to variations in the characteristics of the magnetic materials of the constituent parts, and thus the compression spring 11 Even if the repulsion force f is constant, the differential force of (F−f) varies, and as a result, the operating voltage V varies for each individual object.

Therefore, as described above, when the voltage of the driving power source from the outside is limited and it becomes necessary to keep the operating voltage V within a certain range, the corresponding method is to keep (F−f) within a certain range. A method of adjusting the repulsive force f of the compression spring 11 or changing the magnetic flux Φ ₁ of the magnetic circuit 6 to adjust the suction holding force F is adopted.

This conventional example shows the latter method of adjusting the suction holding force F, and its operation is as follows.

With the above configuration, the gap l between the fixed adsorbent 2 and the adjusted iron core 8
Means that it can be changed by rotating the screw part of the adjusting iron core 8, and the gap 1 becomes a magnetic gap, so that the magnetic resistance of the adjusting magnetic circuit 9 can be changed. That is, when the gap 1 is made small, the magnetic resistance of the adjusting magnetic circuit 9 becomes small, and the total magnetic flux Φ of the permanent magnet 1 flows dispersedly in the magnetic circuit 6 and the adjusting circuit 9 (for leakage flux other than the two magnetic circuits, (Thinking as zero for easy understanding), the magnetic flux Φ ₂ flowing in the adjusting magnetic circuit 9 becomes large, and conversely, the magnetic flux Φ ₁ flowing in the magnetic circuit 6 becomes small and the adsorption holding force F becomes small. On the other hand, conversely, if the gap 1 is increased, the magnetic resistance of the adjusting magnetic circuit 6 increases, so Φ ₂
Becomes smaller, and conversely, Φ ₁ becomes larger, so that the suction holding force F becomes larger.

In this way, the gap l between the adjusting iron core 8 and the fixed adsorption body 2 can be varied, so that the magnetic resistance of the adjusting magnetic circuit 9 is changed to change the magnetic flux Φ ₂ thereof, and finally the magnetic flux Φ of the magnetic circuit 6 is changed.
_It will change ₁ . That is, this changes the attraction holding force F of the movable iron core 3 to the fixed attraction body 2, so that the difference (F−f) from the repulsion force f of the compression spring 11 is kept within a certain width. It means that the variation of can be kept within a certain range.

Problems to be Solved by the Invention However, the above-described configuration has the following problems.

FIG. 6 shows a view when the gap 1 between the adjusting iron core 8 and the fixed adsorbent 2 is being changed. In FIG. 6 (A), l = o,
FIG. 6 (B) shows the case of l = l ₄ , and FIG. 6 (c) shows the case of l = l ₆ . Reference numeral ₁₆ indicates a state in which the tip of the adjusting iron core 3 is located at substantially the same position as the lower end surface of the permanent magnet 1 of the second fixed yoke 5b.

The relationship between the increase of 1 and the operating voltage V is shown in FIG. In FIG. 7, the vertical axis shows the operating voltage V and the horizontal axis shows the gap 1, but the operating voltage V becomes higher as the gap 1 increases. However, the correlation is not linear, and in the vicinity of l = o, V changes greatly with a slight change of l, but l = l ₄ ~
The change in V is very small near l ₆ . This is because in the vicinity of l = o, the magnetic resistance of the adjusting magnetic circuit 9 greatly changes due to the change of l, but when l becomes large, the magnetic resistance is already considerably large for the dimensional change, and the change of the magnetic flux Φ ₂ is almost constant. This is because it does not occur.

As can be seen from these, when the necessary adjustment of the operating voltage V is as low as V ₁ to V ₂ shown in FIG. 7, it is necessary to restrict the dimension width to a slight l. On the contrary, when V has the same width as V _{1 to} V ₂ and is as high as V ₃ to V ₄ , there is a considerable allowance of 1. This means that when the adjusted operating voltage V is low, the operating voltage V changes greatly even if the size of the gap l changes slightly, and therefore it is necessary to improve the dimensional accuracy and it is very difficult to adjust. Become. Moreover, as in this conventional example, the operating voltage V changes even if there is some play between the male screw of the adjusting iron core 8 and the female screw of the second fixed yoke 5b, and adjustment must be made without rattling. I won't.

On the other hand, when the adjustment operating voltage V is high, on the other hand, the tolerance of the gap l is significantly different from the case where V is low even with the same adjustment voltage width. Even if the adjustment width of the operating voltage V is the same, the allowable width of the gap 1 differs depending on whether the adjustment voltage is high or low, which makes the adjustment work difficult.

As described above, the conventional adjustment method has a problem that the adjustment work is extremely difficult because there are both cases where very high accuracy is required and cases where the tolerance is relatively large.

In addition, since the adjusting iron core 8 is fixed by traveling from the second fixed yoke 5b, the gap 1 changes due to external stress, and the characteristic of the operating voltage V is changed. Had.

In order to solve the above problems, the present invention provides an electromagnetic actuator in which the relationship between the operating voltage V and the gap 1 is linearly approximated so that the operating voltage V can be easily adjusted regardless of whether the operating voltage V is low or high.

Means for Solving the Problems In order to solve the above problems, the present invention relates to a permanent magnet, a fixed attraction pair with an adjusting iron core inserted, a magnetic circuit formed between a movable iron core and a fixed yoke, and a magnetic circuit An electromagnetic coil that excites a circuit, and a part of the magnetic circuit that passes through the fixed adsorbent is a shunt magnetic circuit that passes through the fixed adsorbent itself and one end of the fixed adsorbent that passes through the adjusting iron core and the fixed adsorbent again. A first adjustment magnetic circuit passing through the first adjustment magnetic circuit, and the fixed adsorbent not including the movable iron core, the adjustment iron core,
A second adjusting magnetic circuit is provided between the fixed yoke and the permanent magnet.

Operation According to the present invention, the magnetic resistances of the two adjusting magnetic circuits, the first adjusting magnetic circuit and the second adjusting magnetic circuit, are adjusted at the same time by changing the insertion amount of the adjusting iron core into the fixed adsorbing body by the above-mentioned configuration. As a result, the magnetic flux passing through the movable iron core and the fixed adsorbent is adjusted.

Moreover, since the relationship between the insertion amount and the magnetic flux becomes linear, in other words, the relationship between the insertion amount and the operating voltage becomes linear, the operating voltage adjustment becomes easy.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an electromagnetic actuator according to an embodiment of the present invention.

In FIG. 1, the permanent magnet 1 is magnetized in the thickness direction and has a through hole 1a provided in that direction. A fixed adsorbent 2 made of a magnetic material is provided on the permanent magnet 1.
An insertion hole 2a having a female screw portion is formed at a position corresponding to the through hole 1a on the side, so that the movable iron core 3 made of a magnetic material can be adsorbed and detached by the adsorption surface 4. Further, an adjusting iron core 8 having a male screw portion made of a magnetic material is screwed into the insertion hole 2a of the fixed attracting body 2 so as to pass through the through hole 1a of the permanent magnet 1 and screwed. The insertion amount L is variable.

A magnetic circuit 6 of the permanent magnet 1 is formed by the first fixed yoke 5a and the second fixed yoke 5b made of magnetic material, the permanent magnet 1, the fixed attracting body 2 into which the adjusting iron core 8 is inserted, and the movable iron core 3. The movable iron core 3 is adsorbed and held on the fixed adsorbent 2 by the adsorbing surface 4. The driving electromagnetic coil 7 guides the center of the movable iron core 3 so that the movable iron core 3 slides up and down, and excites the magnetic circuit 6. Through hole 1 of permanent magnet 1 of second fixed yoke 5b
A hole 12 having the same size as the through hole 1a is provided at a position corresponding to a so that the adjusting iron core 8 can be rotated from the outside.

Here, the magnetic circuit 6 includes a shunt magnetic circuit 12 that passes through the fixed adsorbent 2 itself in a portion that passes through the fixed adsorbent 2, and a magnetic flux that passes through the fixed adsorbent 2 from the fixed adsorbent 2 through the one-end adjusting iron core 8 again. 1 adjustment magnetic circuit 13.

On the other hand, a second adjusting magnetic circuit 9 which does not include the movable iron core 3 is further formed between the permanent magnet 1, the second fixed yoke 5b, the adjusting iron core 8 and the fixed attracting body 2. A spring receiver 10 is attached to the tip of the movable iron core 3, and a compression spring 11 is provided between the movable iron core 3 and the first fixed yoke 5a.

In the configuration described above, the operating principle is basically the same as that described in the conventional example, and therefore the description thereof is omitted. However, the difference from the conventional example is that the magnetic flux Φ ₁ passing through the magnetic circuit 6 causes the fixed adsorbent 2 to move. when, it divides into [Phi _{1 b} of the first adjustment magnetic circuit 13 through the magnetic flux [Phi _{1 a} and one adjustment fixed adsorbent 2 again iron core 3 from flowing shunt magnetic circuit 12 through the fixed adsorbent 2 itself is through is there. Moreover, this magnetic flux Φ _{1 b} adjustment iron core 8
This is a point that can be changed, that is, changed according to the insertion amount L of.

This means that the magnetic flux Φ ₁ flowing through the magnetic circuit 6 is not only affected by the change in the magnetic flux Φ ₂ of the second adjusting magnetic circuit 9 similar to the conventional example due to the change in the insertion amount L of the adjusting iron core 8. ,
Further, it means that Φ ₁ itself is directly changed by the change of the magnetic flux Φ ₁ b.

The operation will be described below with reference to the drawings. FIG. 2 shows a diagram when the distance between the adjusted iron core 8 of this embodiment and the tip of the insertion hole 2a provided in the fixed adsorption body 2, that is, the insertion amount L is changed. In FIG. 2, (A) shows a state of insertion amount L = L _o ≈0, (B) shows L = L ₁ , and (C) shows L =.
It is shown when L ₂ is set. The magnetic flux passing through the second adjusting magnetic circuit 9 is Φ ₂ , the magnetic flux passing through the magnetic circuit 6 is Φ ₁ , the magnetic flux passing through the first adjusting magnetic circuit 13 is Φ ₁ b, and the magnetic flux passing through the shunt magnetic circuit 12 is Φ ₁ a. Then, Φ ₁ = Φ ₁ a + Φ ₂ b.
On the other hand, if the total magnetic flux from the permanent magnet 1 is Φ,
Φ = Φ ₁ + Φ ₂ . However, for the sake of clarity, the leakage magnetic flux to other than these magnetic circuits will be ignored.

Looking in detail at how the magnetic flux changes under each condition, in the state of FIG. 2 (A), that is, L = L ₀ = ₀ , the adjustment iron core 8 and the second adjustment iron core 8 in the second adjustment magnetic circuit 9 are changed. Since the magnetic gap between the fixed yoke 5b is very large and the magnetic resistance is large,
The magnetic flux Φ ₂ has a very small value. Meanwhile Conversely, the distance between the deepest portion and the distal end portion of the adjusting iron core 8 of the first magnetic flux [Phi ₁ b through the adjustment magnetic circuit 13 is fixed adsorbent 2 of the insertion hole 2a is equal to zero is also a magnetic gap for zero Therefore, the magnetic resistance becomes very small, and Φ ₁ b becomes the maximum value. Flux [Phi ₁ a through the shunt magnetic circuit 12 from the cross-sectional area of the fixed adsorbent 2, and has a magnetic flux amount determined by the area obtained by subtracting the cross-sectional area of the insertion hole 2a.

Next, in the state shown in FIG. 2 (B), that is, L = L ₁ , the adjusting iron core 8 and the second fixed yoke 5b approach each other, and the magnetic gap between them becomes smaller than in the case of L = O. The magnetic resistance of the circuit 9 becomes small and the magnetic flux easily passes, and Φ ₂ increases. Meanwhile, [Phi ₁ b includes a first order distance increases the deepest portion of the insertion hole 2a of the fixed adsorbent 2 and the tip of the adjusting iron core 8
The magnetic resistance of the adjusting magnetic circuit 13 increases, and becomes smaller than the case of L = L ₀ ≈O to a value corresponding to the increase in magnetic resistance.
On the contrary, the reduced amount flows through the second adjusting magnetic circuit 9 in the form of being added to the magnetic flux Φ ₂ . On the other hand, Φ ₁ a is not affected by the second adjusting magnetic circuit 9 and L = L ₀ ≈
Not much different from the case of O.

Further, in the state of FIG. 2 (C), that is, L = L ₂ , the magnetic gap between the adjusting iron core 8 and the second fixed yoke 5b becomes the minimum,
The magnetic resistance of the second adjusting magnetic circuit 9 becomes very small, and the magnetic flux easily passes through. That is, Φ ₂ is maximum compared to when L = L ₀ ≈O and L = L ₁ . On the other hand, Φ ₁ b is the fixed adsorbent 2
And the adjusting iron core 8 become very large, the magnetic resistance of the first adjusting magnetic circuit 13 becomes large, and becomes the minimum Φ ₁
b becomes close to zero. Then, the reduced amount is added to Φ ₂ and flows through the second adjusting magnetic circuit 9. Further, a part of the magnetic flux Φ ₁ a flowing through the shunt magnetic circuit 12 is affected by the fact that the magnetic resistance of the second adjusting magnetic circuit 9 becomes extremely small and the magnetic flux easily passes, and flows in a form that adds to Φ _2. , [Phi ₁ a is _L = L ₀ ≒ O, smaller than at L = _{L 1.}

In order to guarantee such operation, the fixed adsorbent 2
By providing the insertion hole 2a, the magnetic path cross-sectional area of 1 has a relationship with the cross-sectional area of the insertion hole 2a where the magnetic flux passing through the fixed adsorbent 2 changes or decreases as compared with the case where the insertion hole 2a is not provided. I have to do it.

Here, details of the above-mentioned change in magnetic flux will be described with reference to the drawings. Incidentally, the magnetic flux in each condition, for example, [Phi ₁ at the time of L = L ₁
It shall be denoted as b (L ₁ ).

In FIGS. 3A to 3D, the vertical axis represents the amount of magnetic flux under each condition, and the horizontal axis represents the amount L of the adjusting iron core 8 inserted into the fixed adsorbent 2.

The solid line 18 in FIG. 3 (A) indicates the magnetic flux Φ ₁ a of the shunt magnetic circuit 12.
Φ ₁ a hardly changes in L _{0 to} L ₁ as L increases, but decreases greatly in L _{1 to} L ₂ . The amount of decrease from Φ ₁ a (L ₀ ) to Φ ₁ a (L ₂ ) is the magnetic flux Φ ₂ as shown by the alternate long and short dash line 20 in FIG.
Flow as a part of, and increase Φ ₂ .

Next, the solid line 19 in FIG. 3 (B) shows the change of the magnetic flux Φ ₁ b of the first adjusting magnetic circuit 13, which becomes the maximum when L = L ₀ ≈O and thereafter decreases with the increase of L. . The reduction amount from Φ ₁ b (L ₀ ) to Φ ₁ b (L ₂ ) becomes a part of Φ ₂ as shown by the dotted line 21 in FIG.

The solid line 22 in FIG. 3 (C) shows the change of the time flux Φ ₂ of the second adjusting magnetic circuit 9, which is the one-dot chain line 20 showing the decrease of Φ ₁ a and the decrease of Φ ₁ b. It becomes the amount to which the dotted line 21 indicating is added.

Further, the solid line 23 in FIG. 3 (D) shows the change of the flux Φ ₁ when passing through the magnetic circuit 6, and from the relationship of Φ ₁ = Φ ₁ a + Φ ₁ b, the dotted line 24 and Φ ₁ b indicating Φ ₁ a Is added with the alternate long and short dash line 25.

Here, the sum of Φ ₁ and Φ ₂ is the total Φ by the permanent magnet 1, but as can be understood from FIGS. 3C and 3D, Φ ₁ and Φ ₂ Since it is assumed that there is no leakage flux of, Φ = Φ ₁ + Φ ₂ becomes constant.

As described above, the movable iron core 3 and the fixed adsorbent 2 are used in this embodiment.
The magnetic flux Φ ₁ of the magnetic circuit 6 that determines the attraction holding force F between
It shows that the adjustment can be made by changing the insertion amount L of the adjusting iron core 8 in the form as shown in FIG. 3 (D). Moreover, L
The relation between and Φ ₁ is almost linear. That is, it means that the relationship between the insertion amount L and the change in the suction holding force F is substantially linear, and thus the relationship with the operating voltage V is also substantially linear.

In FIG. 4, the horizontal axis represents the insertion amount L and the vertical axis represents the operating voltage V.
Thus, the relationship between the insertion amount L and the operating voltage V in this embodiment is shown. As can be seen, as even if necessary adjustment of the operating voltage V in the present embodiment is low and V ₂ degrees from V _1, V as the same width from V ₁ and V ₂ in the opposite from V ₃ of V ₄ Even when it is extremely high, the regulation amount of the insertion amount L is almost unchanged. Moreover, unlike the conventional example, the operating voltage V does not change significantly even if the L dimension slightly changes, so that the operating voltage V changes even if the screw portion of the adjusting iron core 8 is loose. Will be rarely seen.

It should be noted that the lower end of the adjusting iron core 8 projects from the end face of the second fixed yoke 5b, that is, the insertion amount can be changed to L = L ₂ or more, but in this case, the second fixed yoke 5b and the adjusting iron core 5b. Since the magnetic gap with 8 hardly changes, the adjustment range of the operating voltage V is narrowed, and the adjustment effect is reduced. Therefore, the insertion amount L is usually used in the range of L = L ₀ ≈O to L = L ₂ where the linear relationship with the operating voltage V can be maintained. On the other hand, this range is usually sufficient even if variations in components are included. This is because the adjusting iron core 8 is the second
Since it is not necessary to take the fixed yoke 5b out to the outside, it is possible to prevent the adjustment position of the adjustment iron core 8 from changing due to an external force and the characteristic of the operating voltage V from changing.

In addition, when the adjustment within the above-mentioned adjustment range is not possible, it can be dealt with in combination with the method of changing the repulsive force f of the compression spring 11.

As described above, according to the present invention, the magnetic resistances of the first adjusting magnetic circuit and the second adjusting magnetic circuit are changed at the same time by changing the insertion amount of the adjusting iron core into the fixed adsorbing body, and as a result, the movable magnetic circuit is movable. The magnetic flux passing through the iron core and the fixed adsorbent can be changed and adjusted, and the correlation between the magnetic flux and the insertion amount is made linear. This is to make the correlation between the insertion amount and the operating voltage of the self-holding solenoid linear, and has the effect that the adjustment of the operating voltage becomes very easy by adjusting the insertion amount.

Further, the range in which the relationship between the insertion amount and the operating voltage changes abruptly is eliminated, and it is possible to prevent the characteristic of the operating voltage from changing due to the looseness of the adjusting iron core.

Further, it is possible to prevent the external force from being applied to the adjusted iron core, and it is possible to improve the reliability of the operating voltage characteristic.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic structure of an electromagnetic actuator of one embodiment of the present invention, FIG. 2 is a cross-sectional view of the vicinity of the fixed adsorbent of FIG. 1, and FIG. Showing the relationship between the magnetic fluxes, FIG. 4 is a diagram showing the operating voltage and the amount of adjustment iron core inserted, FIG. 5 is a sectional view showing the schematic structure of a conventional electromagnetic actuator, and FIG. 6 is FIG. FIG. 7 is a cross-sectional view showing the vicinity of the fixed adsorbent, and FIG. 7 is a view showing the relationship between the gap l between the adjusted iron core and the fixed adsorbent and the operating voltage. 1 ... Permanent magnet, 2 ... Fixed adsorbent, 3 ... Movable iron core,
6 ... Magnetic circuit, 8 ... Adjusting iron core, 9 ... Second adjusting magnetic circuit, 13 ... First adjusting magnetic circuit.

Claims (1)

[Claims] 1. A magnetic circuit formed between a permanent magnet, a fixed attracting body having an adjusting iron core inserted therein, a movable iron core, and a fixed yoke, and an electromagnetic coil for exciting the magnetic circuit, the magnetic circuit being fixed. The part passing through the adsorbent is divided into a shunt magnetic circuit passing through the fixed adsorbent itself and a first adjusting magnetic circuit passing from the fixed adsorbent through the adjusting iron core and again passing through the fixed adsorbing body. An electromagnetic actuator in which a second adjusting magnetic circuit is provided between the fixed adsorbent that does not include an iron core, the adjusting iron core, the fixed yoke, and the permanent magnet.