JPH07106119A - Plunger-type solenoid - Google Patents

Abstract

PURPOSE:To provide a solenoid of high response speed by putting a variable plunger core in hollow structure where both end faces in the direction of displacement are open, and setting the thickness so that the induced magnetic flux at the inside periphery may attenuate to the specified rate of the induced magnetic flux density at the outside periphery by the skin effect of the magnetic flux. CONSTITUTION:A coil 2 is wound on a hollow bobbin 1, and a yoke 3 U-shaped in cross section is installed externally around, and a yoke 4 is arranged on the side of the open end of the yoke 3. Moreover, a fixed plunger core 5 is arranged on the side of one end of the hollow part of the coil 2, being fixed to the yoke 3. A variable plunger core 8 in hollow structure, which is to be displaced, is arranged on the side of the other end of the hollow part of the coil 2. A pipe 7 is inscribed in the inside periphery of the hollow part of a bobbin 1. Furthermore, the thickness of the variable plunger core 8 is set in the range where the induced magnetic flux at the inside periphery attenuates to 1/2-1/4 of the induced magnetic flux at the outside periphery by the skin effect of the magnetic flux.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger type solenoid used as an electromagnetic converter. More specifically, the present invention relates to a plunger type solenoid capable of shortening the response time from the energization of the movable plunger core to the start of movement and increasing the moving speed in the bobbin so that the converter has a high-speed response. Is.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view of a plunger type solenoid showing a conventional embodiment. A coil 2 is wound around a hollow bobbin 1, and a first U-shaped cross-section is formed around the bobbin 1.
A yoke 3 is externally provided, and a second yoke is provided on the open end side of the first yoke 3.
A yoke 4 is arranged. A fixed plunger core 5 is disposed on one end side of the hollow portion of the bobbin 2, and the first yoke 3
It is fixedly held at. A round bar movable plunger core 6 that displaces the other end of the hollow portion of the bobbin 2 is provided. A pipe 7 is inscribed on the inner peripheral surface of the hollow portion of the bobbin 1. Although not shown because it is well known,
The round bar plunger core 6 is biased by a spring so as to be separated from the fixed plunger core 5, but is stopped at the position shown in the figure by an appropriate member. In such a conventional example, the coil 2 wound around the hollow bobbin 1
When a current is applied to the solenoid, the magnetomotive force excited by the solenoid produces a magnetic flux in the round rod movable plunger core 6 located at one end of the bobbin 1, and interacts with the magnetizing force produced by the magnetomotive force of the solenoid. And a suction force is generated. The round rod movable plunger core 6 moves inwardly of the bobbin 1 following this suction force, and stops when it strikes the fixed plunger core 5.

In order to obtain the attraction force F of the solenoid, conventionally, the facing cross-sectional area of the movable plunger is S, the magnetic susceptibility of the gap (non-magnetic path) between the movable plunger core and the pipe is μ ₀ , and the magnetic flux density is When ^{B, F = (B 2/} 2
The principle formula of μ ₀ ) × S is adopted. If the iron core is sufficiently saturated, the term including the magnetic susceptibility μ ₀ and the magnetic flux density B of the air gap (non-magnetic path) between the movable plunger core and the pipe can be regarded as a constant term. When the constant is k, F = kS, and the attractive force F is proportional to the facing cross-sectional area S of the movable plunger core. Therefore, in the conventional structure as shown in FIG. 2, in order to obtain a strong attractive force, the core of the plunger is generally made thick to increase the facing cross-sectional area so that a large amount of magnetic flux can pass therethrough. It was

Further, the above formula F = (B ² / 2μ ₀ ) × S
As a prerequisite, a sufficiently long time is required for the induced magnetization, but a sufficient margin can be taken in the conventional large / medium type and relatively slow response equipment, so
There was no need to consider shorter times. That is,
The time term was not included in the formula. Therefore, for high-speed response, since (force) = (mass) × (acceleration), the stronger the force, the greater the acceleration.
It was often thought that speed would increase.

[0005]

However, when the movable plunger core is thickened, the mass of the movable plunger core is very large and the inertia is increased because the material is usually iron.
This means that the time required to start the displacement when the movable plunger core is displaced is increased, and the response time is increased, which is not applicable to high-speed response of about 20 msec or less. was there. Also, if the movable plunger core is made thicker, it is necessary to increase the electromotive force to the coil, but in small precision equipment, etc., a small battery is used, so there is a limit to the generation of a large electromotive force. Unlike a medium-sized device that responds at a relatively low speed, there was no room to secure a sufficient margin in terms of time and electromotive force, and there was also a problem in terms of power saving.

If the gap between the movable plunger core and the pipe is constant, the ratio of the cross-sectional void area to the facing cross-sectional area of the movable plunger core decreases as the radius of the movable plunger core increases. When the core is thickened, the voids are relatively small,
The air resistance when the movable plunger core is displaced is further increased. This leads to deterioration of response characteristics with respect to time, and making the movable plunger core thick has been a problem in terms of high-speed response. Increasing the air gap with the thickness of the movable plunger core was a negative factor from the viewpoint of inductive gain of the magnetizing force and was not a good improvement measure. To solve this problem, there is a movable plunger core in which a groove or a spiral groove is formed on the outer peripheral surface for the passage of air. However, since the air gap is substantially increased, the magnetic efficiency is reduced. There were drawbacks in terms.

Furthermore, it has recently been found that, when the movable plunger core is magnetized, in reality, there is a skin effect of magnetic flux, so that it is not magnetized to a deep layer in an extremely short time. Therefore, in the iron core used in a high frequency transformer or the like, it is difficult for the magnetic flux to pass through due to the skin effect of the magnetic flux, and the apparent magnetic permeability is reduced. FIG. 3 is a graph showing the skin effect of the hysteresis loop in the material, where the material is iron. The horizontal axis of the graph represents the distance from the surface of the material. The vertical axis represents the induced magnetic flux density. This graph shows that the hysteresis loop in the material becomes smaller as it goes inward due to the skin effect. Therefore, even if the movable plunger core is thickened, there is a drawback that the effect of thickening is small because the inside is not magnetized by the excitation by the high frequency pulse wave of about 20 msec or less.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a plunger type solenoid capable of a high-speed response of about 20 msec or less.

[0009]

In order to achieve the above object, the present invention provides a bobbin, a coil wound around the bobbin, and a movable plunger disposed so as to be axially displaceable within the bobbin. A core, a fixed plunger core disposed with a gap between the movable plunger core and the tip end surface portion of the movable plunger core at a displacement movement end position in the bobbin, and a yoke provided outside the bobbin. , The movable plunger core has a hollow structure in which both end faces in the displacement direction are open, and the wall thickness is such that the induced magnetic flux density on the inner peripheral surface is 1/2 to 1/1 / of the outer peripheral surface due to the skin effect of the magnetic flux. 4 is set to a range that attenuates, or the integrated area related to the wall thickness of the induced magnetic flux density is added, and the integrated area is the magnetic field when the movable plunger core is a round bar. It is designed to be set in the range of 1/2 to 2/3 of the total integrated area related to the thickness of the density, and particularly when the material is iron-based, the thickness is 0.6 to 1.2 mm. It was done as it was.

[0010]

The mass of the movable plunger core is reduced and the weight is reduced, which leads to the reduction of the driving force required for movement, and the response time proportional to the mass is also shortened due to the reduction of the mass.
Moreover, since the air flowability is increased by adopting the above hollow structure, it is possible to reduce the air resistance when the movable plunger core is displaced in the bobbin.
It is possible to reduce the gap between the movable plunger core and the bobbin, further improve the magnetic efficiency, and achieve a high-speed response. Furthermore, due to the skin effect of the magnetic flux, the hollow structure contributes to the attractive force very effectively without loss in magnetic characteristics. As described above, the above configuration contributes to the high-speed response and acts in all of reduction of mass, improvement of air fluidity and improvement of magnetic efficiency due to improvement of air fluidity, and improvement of magnetic efficiency due to skin effect.

[0011]

EXAMPLES The present invention will be described in detail below with reference to illustrated examples. FIG. 1 is a sectional view showing a plunger type solenoid according to an embodiment of the present invention. Hollow bobbin 1
A coil 2 is wound around the first yoke 3, and a first yoke 3 having a U-shaped cross section is provided around the coil 2. A second yoke 4 is disposed on the open end side of the first yoke 3. A fixed plunger core 5 is arranged on one end side of the hollow portion of the bobbin 2 and is fixedly held by the first yoke 3. A movable plunger core 8 having a hollow structure that displaces the other end of the hollow portion of the bobbin 2 is provided. A pipe 7 is inscribed on the inner peripheral surface of the hollow portion of the bobbin 1. Movable plunger core 8 with hollow structure
Has a cylindrical shape. Further, there is a slight gap between the outer peripheral surface of the hollow movable plunger core 8 and the inner peripheral surface of the pipe 7.

Is the wall thickness of the hollow movable plunger core 8 set within a range in which the induced magnetic flux density on the inner peripheral surface is attenuated to 1/2 to 1/4 of the induced magnetic flux density on the outer peripheral surface due to the skin effect of the magnetic flux? Alternatively, the wall thickness of the hollow movable plunger core 8 is obtained by adding the integral area of the wall thickness of the induced magnetic flux density, and the integrated area is the wall thickness of the magnetic flux density when the movable plunger core is a round bar. Is set to be in the range of 1/2 to 2/3 of the total integrated area of the above, especially when the material is iron-based, the wall thickness is 0.6.
The optimum range is from 1.2 mm to 1.2 mm.

[0013]

As described above, in the plunger type solenoid according to the present invention, the thickness of the movable plunger core is such that the movable plunger core has a hollow structure in which both end faces in the displacement direction are open. Is set to a range in which the induced magnetic flux density on the inner peripheral surface is attenuated to 1/2 to 1/4 of the induced magnetic flux density on the outer peripheral surface due to the skin effect of the magnetic flux, or is related to the thickness of the induced magnetic flux density. The integrated area is added, and the integrated area is set in the range of 1/2 to 2/3 of the total integrated area related to the wall thickness of the magnetic flux density when the movable plunger core is a round bar. In particular, when the material is iron-based, the wall thickness is made to be 0.6 to 1.2 mm. Therefore, the mass of the movable plunger core is reduced, the weight is reduced, and the driving force required for movement is reduced. Light Leads to, also improves the response time proportional to the mass. In addition, since the hollow structure described above can increase the fluidity of air and reduce the air resistance when the movable plunger core is displaced in the bobbin, the air gap between the movable plunger core and the bobbin can be reduced. Can be reduced, magnetic efficiency can be further improved, and high-speed response can be achieved. Further, by adopting the above hollow structure, the skin effect of the magnetic flux can be effectively obtained, and an extremely efficient attractive force can be obtained without loss in magnetic characteristics. In this way, by using the above-mentioned structure, it is possible to reduce the mass, improve the air fluidity, and improve the magnetic efficiency due to the skin effect at the same time. The arrival time is shortened, the rising characteristic is improved, and the high-speed response is significantly improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a plunger type solenoid according to an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional plunger type solenoid.

FIG. 3 is a graph showing a skin effect of a hysteresis loop in a material.

[Explanation of symbols]

 1 bobbin 2 coil 3 first yoke 4 second yoke 5 fixed plunger core 6 round bar movable plunger core 7 pipe 8 hollow movable plunger core

Claims (3)

[Claims] 1. A bobbin, a coil wound around the bobbin, a movable plunger core disposed so as to be axially displaceable in the bobbin, and a displacement of the movable plunger core in the bobbin. The movable plunger core is provided with a fixed plunger core disposed with a gap between the distal end surface portion of the movable plunger core and the bobbin at a movement end position, and the movable plunger core in the displacement direction. The hollow structure is open at both end surfaces, and its wall thickness is set within the range where the induced magnetic flux density on the inner peripheral surface is attenuated to 1/2 to 1/4 of the induced magnetic flux density on the outer peripheral surface due to the skin effect of magnetic flux. Plunger type solenoid characterized in that 2. The thickness of the movable plunger core is obtained by adding the integral area of the induced magnetic flux density with respect to the thickness, and the integrated area is the thickness of the magnetic flux density when the movable plunger core is a round bar. 2. The plunger type solenoid according to claim 1, wherein the plunger type solenoid is set in the range of 1/2 to 2/3 of the total integrated area with respect to. 3. A plunger type solenoid according to claim 1, wherein the movable plunger core is made of iron and has a wall thickness of 0.6 to 1.2 mm.