JPH07177721A - Electromagnetic actuator - Google Patents

Abstract

PURPOSE:To extend the life by increasing the abrasion resistance. CONSTITUTION:In an electromagnetic actuator wherein a shaft 13 of a movable iron core 14 is supported by sliding bearings 12A, 12B of a fixed iron core 11 so that the shaft 13 can move right and left and the movable iron core 14 is sucked by the fixed iron core 11 by applying electric current to a conductor coil 15 and then the shaft 13 is moved in the X direction indicated by the arrow, the shaft 13 is formed of non-magnetic austenitic stainless steel. Then, an Fe2B layer of thickness of 10-80mum is formed on the surface of the shaft 13 to increase the surface hardness to Hv1300-1800. By this method, even when the actuator is used in an atmosphere wherein there is mush dust, and a foreign matter enters between the shaft and the bearings, abrasion on a sliding contact face can be minimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic actuator for opening / closing a fluid control valve or controlling the opening thereof.

[0002]

2. Description of the Related Art Generally, an electromagnetic actuator of this type has a fixed iron core and a movable iron core made of a magnetic material, a shaft provided on one of them, and the shaft provided on the other side in the axial direction thereof. A bearing that movably supports the
And a conducting wire coil which is provided on one of the fixed iron core and the movable iron core and generates a magnetic flux capable of attracting the other.

The bearing includes a plain bearing in which the entire outer peripheral surface of the shaft is in sliding contact with the entire inner peripheral surface of the bearing surface, and a rolling bearing in which both parts are in rolling contact. In either case, a bearing load due to magnetic flux is applied to the shaft. In order to prevent the increase in the magnetic field, the shaft is made of a non-magnetic material such as austenitic stainless steel.

[0004]

However, in such a conventional electromagnetic actuator using the sliding bearing as the bearing, the contact area between the shaft and the bearing is relatively large, and the shaft and the bearing are relatively large. Although the relative movement speed with the shaft is not so high, it is still impossible to obtain sufficient surface hardness by subjecting the shaft made of austenitic stainless steel to general heat treatment, and the shaft surface wears in a relatively short time. There is a problem that the axial center of the movable iron core and the axial center of the fixed iron core deviate from each other, resulting in uneven magnetic flux density, which increases the load on the shaft and the bearing and shortens the life. Also,
In the case of sliding bearings, the frictional force acting between the shaft and the bearing is extremely high, and there is a disadvantage that the output (suction force) is reduced and control hysteresis is likely to occur.

Generally, the wear between the shaft and the slide bearing which are in sliding contact with each other is caused by the binary abrasive wear caused by the hard material of one being scraped off the soft material of the other, and the foreign matter being caught in the gap between them. It is considered to be either ternary abrasive wear or adhesive wear in which a part of one surface layer is transferred to the other.

In order to solve the above-mentioned inconvenience, it is desirable to use a sliding pair as a rolling pair, but in that case, the contact area between the shaft and the bearing is extremely small, the surface pressure becomes extremely large, and the wear rate of the shaft increases. Fatigue wear also occurs with the rapid increase. Therefore, even if only the surface layer of the shaft is hardened, the stainless steel of the base material may yield due to local high surface pressure and the shaft itself may be plastically deformed.

[0007] Various other solutions have been devised, but the current situation has not been a radical solution. The present invention has been made in view of the above points, and it is an object of the present invention to improve wear resistance and significantly extend life.

[0008]

In order to achieve the above object, the present invention has a fixed iron core and a movable iron core each made of a magnetic material, and a shaft provided concentrically with the movable iron core.
The slide bearing is provided on the fixed iron core to movably support the shaft in the axial direction and restrains the movement in a direction orthogonal to the axial direction, and is provided on one of the fixed iron core and the movable iron core. In an electromagnetic actuator consisting of a conductor coil that generates a magnetic flux that can attract the other,
The present invention provides an electromagnetic actuator in which the shaft is made of a non-magnetic material, austenitic stainless steel, and a Fe ₂ B layer having a thickness of 10 to 80 μm is formed on the surface thereof.

Further, a fixed iron core and a movable iron core each made of a magnetic material, a shaft concentric with the movable iron core, and the shaft provided on the fixed iron core are movably supported in the axial direction thereof. In an electromagnetic actuator consisting of a rolling bearing for restraining movement in a direction orthogonal to the axial direction, and a wire coil which is provided on any one of the fixed iron core and the movable iron core and generates a magnetic flux capable of attracting the other, The shaft is made of austenitic stainless steel, which is a non-magnetic material, and the surface of which Fe has a thickness of 10 to 80 μm
Electromagnetic actuator, characterized in that the formation of the ₂ B layer are also provided.

In each of the above-mentioned electromagnetic actuators, a hardened layer is formed by pre-processing on the sliding contact surface of the shaft with the bearing, and the hardened layer has a thickness of 10 to 80 μm.
It is even better to form an e ₂ B layer.

[0011]

By constructing the electromagnetic actuator according to the present invention as described above, the surface hardness of the shaft made of stainless steel having the Fe ₂ B (boron) layer is, for example, H
v1300 to 1800, which is extremely high, and at the same time the surface hardness of the bearing material is increased, the above-mentioned binary abrasive wear and ternary abrasive wear are significantly reduced. Further, since the Fe ₂ B layer formed on the shaft surface is inactive, there is no possibility of causing adhesive wear, and the layer is wedged into the base material and is extremely strong.

The Fe ₂ B layer requires a minimum thickness of 10 μm in consideration of variations in cylindricity, surface roughness and boron penetration of the surface of the Fe ₂ B layer that is in sliding contact with the shaft bearing. Become. Further, if the thickness exceeds 80 μm, impurities may increase in the boundary line with the base material and peeling may occur. Therefore, the thickness of the Fe ₂ B layer is preferably set to 10 to 80 μm. Further, when there is a risk of yielding of the shaft due to the static local high surface pressure state, if a hardened layer is preliminarily formed on the surface of the shaft by pre-processing such as forging, and a Fe ₂ B layer is formed thereon. Good.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a vertical sectional view showing a first embodiment of the present invention.

The electromagnetic actuator 10 has a frame-shaped fixed iron core 11, sliding bearings 12A and 12B fixed to the left and right ends of the fixed iron core 11, and left and right sliding bearings 12A and 12B. The shaft 13 slidably supported in the direction, and the space 1 that is integrally fixed to the shaft 13 concentrically and is formed at the center of the fixed iron core 11.
Movable iron core 14 that moves left and right in 1a without contact
And a conductive wire coil 15 embedded in the fixed iron core 11 concentrically with the axis of the shaft 13. Both the fixed iron core 11 and the movable iron core 14 are made of a magnetic material, and the shaft 13 is made of a non-magnetic material such as austenitic stainless steel.

When the conductor coil 15 is energized, the movable iron core 14 is attracted to the fixed iron core 11 and moves along with the shaft 13 in the arrow X direction. At this time, since the shaft 13 is made of a non-magnetic material, the bearing load is not increased by the magnetic flux generated from the conductor coil 15.

In this embodiment, the shaft 13 made of austenitic stainless steel has a surface of F having a thickness of 10 to 80 μm on the surface thereof.
The e ₂ B layer is formed to increase the surface hardness of the shaft 13. This Fe ₂ B layer can be formed at low cost by infiltrating boron on the metal surface by a molten salt dipping method. FIG. 2 shows a Fe ₂ B layer 200 formed by a molten salt dipping method on a base material 100 made of stainless steel such as the shaft 13.
FIG. 4 is a cross-sectional view showing a tissue state in which the ridges are formed at a high magnification. When forming a Fe ₂ B layers by such molten salt dip method, it is not easily peeled Fe ₂ B layers is formed in a wedge shape with respect to the base material.

The Fe ₂ B layer thus formed is
In consideration of variations in the cylindricity of the shaft 13, the surface roughness, and the penetration depth of boron, it is preferable that at least the thickness (depth) t of the thickest portion in FIG. 2 is 10 μm or more. As a result, the base material can be sufficiently covered even at the thinnest portion of the Fe ₂ B layer on the surface of the shaft 13. On the other hand, if the thickness t exceeds 80 μm, the amount of impurities in the boundary layer with the base material increases and peeling easily occurs.
The thickness t of the thickest part of the ₂ B layer is preferably 80 μm or less.

Since this embodiment has the above-mentioned structure, the hardness of the surface of the shaft 13 on which the Fe ₂ B layer is formed has a high hardness which cannot be obtained by ordinary nitriding or quenching, for example, Hv130.
It reaches 0-1800. If the hardness of the bearing surfaces of the plain bearings 12A and 12B is increased in parallel with the boron treatment on the shaft surface, the above-mentioned binary abrasive wear and ternary abrasive wear will be greatly reduced, especially under bad operating conditions. Thus, even when foreign matter is caught between the shaft and the bearing, the wear can be suppressed to the minimum and the life of the electromagnetic actuator can be remarkably extended.

Next, FIG. 3 is a longitudinal sectional view showing a second embodiment of the present invention, in which the same parts as those in the above-mentioned first embodiment are designated by the same reference numerals and their detailed description will be given. Omit it.
In the second embodiment, the shaft 13 integrated with the movable iron core 14 is
The rolling bearings 22A and 22B fixed to the fixed iron core 11 are supported, and the other structures are the same as those in the first embodiment.

In this electromagnetic actuator 22 as well, the shaft 1
By forming the Fe ₂ B layer on the surface of No. 3, the surface hardness can be increased and wear resistance can be greatly improved, and at the same time, the slidability of the shaft 13 can be improved and the output can be reduced and control hysteresis can be obtained. Can be prevented.

However, in the second embodiment, the surface pressure applied to the shaft 13 is remarkably increased, the friction speed is rapidly increased, and the base material stainless steel may yield and cause plastic deformation.
In that case, the Fe ₂ B layer may be formed after the surface of the shaft 13 is pre-processed such as forging to form a hardened layer.

In each of the above embodiments, the wire coil for generating the magnetic flux is provided on the fixed iron core side, but it may be provided on the movable iron core side. Further, the material of the shaft is not limited to austenitic stainless steel, and any ferrous alloy may be used as long as it is a non-magnetic material having a hardness comparable to that.

Further, in each of the above embodiments, the inner peripheral surface of the fixed iron core and the outer peripheral surface of the movable iron core are not in contact with each other to reduce the frictional resistance during movement of the movable iron core. Even in the case of the actuator, the wear resistance can be improved by forming the Fe ₂ B layer on at least one of the sliding contact surfaces.

[0024]

As described above, in the electromagnetic actuator according to the present invention, the shaft of the movable core that is slidably supported by the sliding bearing on the fixed core side is made of austenitic stainless steel, and the surface of the austenitic stainless steel is the maximum. The thickness of the thick part is 10-8
Since the Fe ₂ B layer having a thickness of 0 μm is formed, the wear resistance is improved, and the wear due to the meshing of foreign matters is reduced to reduce the wear of the electromagnetic actuator even under the condition of use in an atmosphere that is particularly poor and contains much dust. The life can be greatly extended.

Since the Fe ₂ B layer is an inactive layer, the adhesion resistance is also improved, and at the same time, the Fe ₂ B layer is formed by infiltrating boron on the metal surface by a molten salt dipping method. Therefore, the cost is extremely low.

Further, in the case where the shaft having the Fe ₂ B layer on the surface is supported by the rolling bearing, in addition to the same effects as the above, problems such as a decrease in output and the occurrence of control hysteresis are solved. It becomes possible to do.

Further, in each of the above-mentioned electromagnetic actuators, when the Fe ₂ B layer is formed on the hardened layer formed by pre-processing on the surface of the shaft which is in sliding contact with the bearing, the surface pressure of the shaft surface is reduced. The base material of the shaft does not yield even if it can be very large.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a textured state of a Fe ₂ B layer formed on the surface of a base material.

FIG. 3 is a vertical sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

 10, 20: Electromagnetic actuator 11: Fixed iron core 12A, 12B: Sliding bearing 13: Shaft 14: Movable iron core 15: Conductor coil 22A, 22B: Rolling bearing

Claims (3)

[Claims] 1. A fixed iron core and a movable iron core each made of a magnetic material, a shaft concentric with the movable iron core, and a shaft provided on the fixed iron core and movably supported in the axial direction thereof. In an electromagnetic actuator consisting of a slide bearing for restraining movement in a direction orthogonal to the axial direction, and a conductor coil for generating a magnetic flux that can be attracted to the other of the fixed iron core and the movable iron core, An electromagnetic actuator characterized in that a shaft is made of austenitic stainless steel which is a non-magnetic material, and a Fe ₂ B layer having a thickness of 10 to 80 μm is formed on the surface thereof. 2. A fixed iron core and a movable iron core each made of a magnetic material, a shaft concentric with the movable iron core, and a shaft provided on the fixed iron core and movably supported in the axial direction thereof. A rolling bearing for restraining movement in a direction orthogonal to an axial direction, and an electromagnetic actuator comprising a wire coil for generating magnetic flux capable of attracting the other of the fixed iron core and the movable iron core, An electromagnetic actuator characterized in that a shaft is made of austenitic stainless steel which is a non-magnetic material, and a Fe ₂ B layer having a thickness of 10 to 80 μm is formed on the surface thereof. 3. The electromagnetic actuator according to claim 1 or 2, wherein a hardened layer by pre-processing is formed on a sliding contact surface of the shaft with the bearing, and the hardened layer has a thickness of 10 to 80.
An electromagnetic actuator characterized in that a Fe ₂ B layer of μm is formed.