JP2649852B2 - Solenoid with magnetic sensor - Google Patents

Description

The present invention relates to, for example, a solenoid actuator used for an automatic switching valve for gas piping, and more particularly, to a leakage magnetic flux generated from an outer casing frame of the solenoid. The present invention relates to a solenoid capable of detecting a change of the plunger and discriminating the plunger on / off operation using a magnetic sensor that converts the change into an electric signal.

[Prior Art] Generally, as shown in FIG.
As a structure for detecting the operation of the magnet, the magnetic flux leaking into the external space, which is generated when the plunger 51 is separated from the state in which the plunger 51 is in contact with the stopper 52 by being attracted into the exciting coil 57 and is separated from the stopper 52, is excited. There is known a structure in which detection is performed near the outer surface of the coil unit 57 for use.

That is, the lead is formed along the outer surface of the exciting coil portion 57 between the side edges of the side plates 53 and 53 'of the outer casing frame made of a metal magnetic material having a substantially U-shaped cross section and forming a part of the magnetic path. A switch, a magnetoresistive element, a magnetoelectric conversion element 54 such as a Hall IC is installed, and an increase / decrease of a leakage magnetic flux from the coil section 57 is sensed in an analog manner, thereby detecting the insertion / removal state of the plunger 51. Activates the element 54 and detects it (not shown)
Output to

[Problems to be Solved by the Invention] However, as described above, the conventional device has a structure in which the analog change of the leakage magnetic flux is captured by the magnetoelectric conversion element 54. The operating point (threshold) of the magnetoelectric conversion element 54 may differ from product to product due to variations in sensitivity (variations in component accuracy), variations in assembly, and the like. Therefore,
There was a problem that stable operation characteristics could not be obtained.

The present invention solves the above-mentioned problems, and has a simple structure.
It is an object of the present invention to provide a solenoid with a magnetic sensor that can reliably open and close the magneto-electric conversion element even if the sensitivity and the like of the magneto-electric conversion element vary.

Means for Solving the Problems To achieve the above object, a solenoid with a magnetic sensor according to the present invention comprises an outer casing frame forming a magnetic path yoke, an exciting coil held by the outer casing frame, and an exciting coil. A solenoid provided with a magnetic sensor provided with a plunger that is removably inserted into and retracted from the hollow portion of the coil for use, and a magnetoelectric conversion element that detects a change in a magnetic field, and provided so that the operation of the plunger can be electrically detected. By notching the side plate of the outer casing frame so as to have a predetermined gap, an air gap is formed in a magnetic circuit in the side plate, and the magnetoelectric conversion element is disposed near the air gap. And

[Operation] In this configuration, when the plunger is attracted into the hollow portion by applying a voltage to the exciting coil, the magnetic circuit including the outer casing frame is closed, and the air gap in the air gap of the outer casing frame is closed. The opposite ends will have different magnetic poles.

Therefore, each detecting section of the magnetoelectric conversion element such as a reed switch surely takes a different magnetic pole due to the influence of the leakage magnetic flux generated near the air gap of the frame, and the magnetic flux flows in the same direction, and the switch operates. ON.

On the other hand, when the plunger is disengaged, the opposing ends of the frame with the air gap therebetween bear the same magnetic pole. Along with this, the respective magnetic detection units of the magnetoelectric conversion elements arranged near the outside of the air gap also take on the same magnetic pole under the influence of the leakage magnetic flux. As a result, since the detection units repel each other, the magnetoelectric conversion element
It turns off.

[Example] Hereinafter, a more detailed description will be given based on an example of the present invention illustrated in the drawings.

Reference numeral 1 denotes a solenoid actuator with a magnetic sensor according to the present embodiment, which mainly includes an outer casing frame 2, an exciting coil 4, a plunger 6, a permanent magnet 7, and a reed switch 9 as a magnetoelectric conversion element.

The outer casing frame 2 is made of a magnetic material such as iron, and is formed in a substantially U-shaped cross section by a bottom plate surrounding the bottom surface and both side surfaces of the exciting coil 4 and two side plates. Further, in the present embodiment, an air gap 3 is formed in one side plate 21 of the outer casing frame 2 and is cut into an appropriate shape so as to have a predetermined gap. As shown in FIG. 3 (a), the notch shape of the air gap 3 is substantially T-shaped.
The shape is not limited to the one formed by the narrow gap portion 3a and the wide gap portion 3b, and may be any shape as long as at least the side edge 21a is cut off at a predetermined interval at a substantially central portion thereof. You may. As shown in FIG. 3 (b), the frame portion 21b on the opposite side of the side edge 21a is further provided with, for example, a V-shaped notch groove portion 3c, and the magnetic resistance of the frame portion 21b in the vicinity thereof is formed. Is increased, the leakage magnetic flux around the position A where the magnetoelectric conversion element is disposed can be further increased.

The exciting coil 4 is wound around a coil bobbin 5 made of plastic or the like in which a hollow portion 5a for slidably receiving the plunger 6 is formed at the center.

The reed switch 9 is located in the vicinity of the air gap 3 formed in the outer casing frame 2 and at a position adjacent to and opposed to the air gap 3 and affected by the leakage magnetic flux, that is, within a range of A in FIG. Then, it is mounted and held in a case 9c having predetermined wiring (not shown), and is fixed to the frame 2 by bolts (not shown) as shown in FIG.

In FIG. 2, reference numeral 7 denotes a self-holding permanent magnet arranged adjacent to the exciting coil 4 so as to lock the plunger 6 at a predetermined position when the plunger 6 is attracted. It is a spacer made of a magnetic material interposed between the plunger 7 and the plunger 6. Further, 8 is a cap member for fixing, 10 is an imaginary line, is a compression spring for return,
Reference numeral 11 denotes a work provided at one end of the plunger 6, which is a valve element such as an automatic switching valve installed in a gas pipe. Reference numeral 12 denotes a stopper portion protrudingly formed on the frame bottom plate 21e facing the distal end 6a of the plunger 6.

Next, the operation of the solenoid 1 with a magnetic sensor according to the present embodiment having the above configuration will be described.

For example, when a pulse voltage is applied to the exciting coil 4,
The plunger 6 is attracted by the magnetic force of the coil 4 and is instantaneously immersed in the hollow portion 5a of the coil bobbin 5,
The tip 6a contacts the stopper 12 made of a magnetic material.

As a result, even after the voltage to the coil 4 is reduced, a magnetic circuit is formed by the frame 2, the plunger 6, the permanent magnet 7, and the stopper 12, as shown in FIG. In this magnetic circuit, a magnetic flux flows in the frame side plate 21 in which the air gap 3 is formed, in the direction indicated by the arrow X, and the frame portion 21 facing the air gap 3 across the air gap 3.
c and 21d have different polarities. That is,
As is clear from the magnetic equivalent circuit diagram shown in FIG. 5 (a), each end 21c has a N pole, 2
1d will have an S pole.

Therefore, the magnetic leads 9a, 9b of the reed switch 9 disposed adjacent to the air gap 3 are affected by the leakage magnetic fluxes of the different magnetic poles from the frame portions 21c, 21d, respectively, as shown in the drawing. As shown, they have different magnetic poles. That is, when the frame portion 21c has the N pole, the magnetic lead 9a has the S pole, and when the frame portion 21d has the S pole, the magnetic lead 9b has the N pole. As a result, the leads 9a and 9b are drawn toward each other, and the reed switch 9 is turned on.

On the other hand, when a pulse voltage of a reverse current is applied to the exciting coil 4, the attractive force between the plunger 6 and the stopper 12 is instantaneously released, so that the resilient force of the return spring 10 causes the plunger 6 to move inside the coil 4, that is, the coil bobbin. 5 hollows
Leave and return from inside 5a. At this time, the flow of the magnetic flux occurs in the directions indicated by arrows Y and Z in FIG. 4 (b). That is, as shown in the magnetic equivalent circuit diagram of FIG. 5 (b), since the plunger 6 and the stopper 12 are separated,
A magnetic circuit is formed by the two permanent magnets 7, 7 including 7a and the yoke 2, and the S poles appear on both the frame portions 21c, 21d. Therefore, the leakage magnetic flux generated near the air gap 3 becomes a single pole. As a result, both the leads 9a and 9b of the reed switch 9 become N poles and repel each other.
It will be FF.

Therefore, the magnetic field in which the reed switch 9 is turned on and the magnetic field in which the reed switch 9 is turned off are generated digitally differently when the plunger 6 is attracted and when the plunger 6 is detached, regardless of the strength of the magnetic flux.

However, in the present embodiment, the side plate 21 of the frame 2
And an air gap 3 cut out to have a predetermined gap.
, The amount of leakage magnetic flux is larger than that of the conventional one. In addition, the air gap 3 is changed as shown in FIG.
If the shape as shown in FIG. 1 is used, the leakage magnetic flux affecting the reed switch 9 can be further increased.

Here, FIG. 6 is a graph showing the magnetic characteristics of the solenoid 1 with a magnetic sensor of the present embodiment. As shown in FIG. 7, this graph shows the position P on the measurement line A1 passing through the range A and substantially facing the notch groove 3b, that is, the frame portion 21c shown in FIG. In the vicinity, a probe of a Gauss meter (not shown) is fixed, and the plunger 6 is moved upward from the suction position with the stopper 12 to be gradually separated, and the relationship between the moving distance and the Gauss value is shown.

From FIG. 6, it can be seen that the magnetic pole near the measuring point P, that is, the magnetic pole of the frame portion 21c forming the air gap 3, takes on the N pole when the plunger 6 is attracted and the S pole when the plunger 6 is separated. I understand.

In the above-described embodiment, the reed switch 9 is used as the magnetoelectric conversion element. However, the present invention is not limited to this, and it goes without saying that a magnetoresistance element or a Hall IC may be used.

Further, the solenoid with a magnetic sensor of the present invention is applicable to various types of solenoids in addition to the solenoid 1 according to the above-described embodiment. For example, the present invention can be applied not only to the permanent magnet disposed at the above-mentioned position but also to the permanent magnet disposed at the position of the stopper 12 of the solenoid 1. Further, the present invention can be applied to a solenoid in which the plunger 6 is manually pressed to be attracted to the permanent magnet or the stopper 12 and energized to the coil 4 to be separated from the permanent magnet.

[Effects of the Invention] According to the solenoid with a magnetic sensor of the present invention, since the air gap having a predetermined gap is provided in the outer casing frame forming the magnetic path yoke, it is generated when the plunger is attracted and detached. The change of the leakage magnetic flux can be detected as a digital change due to the change of the S and N polarities. Therefore, the opening / closing operation of the magnetoelectric conversion element disposed near the notch is reliably performed as an operation associated with a change in polarity regardless of the strength of the leakage magnetic flux to be detected. Therefore, even if there is a product error in the magnetoelectric conversion element, stable operation characteristics can be obtained, and adjustment at the time of mounting is not required, and the manufacturing and assembling steps can be simplified.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a solenoid with a magnetic sensor according to the present invention, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. FIG. 3 (b) is a side view showing another aspect of the notch, and FIGS. 4 (a) and (b) are diagrams for explaining the operation principle of the magnetoelectric conversion element. 5, (a) and (b) are diagrams for explaining a magnetic equivalent circuit, FIG. 6 is a diagram showing magnetic characteristics of the solenoid with a magnetic sensor of the embodiment, and FIG. FIG. 8A is a schematic side view for explaining a method of measuring the magnetic characteristic value, FIG. 8A is a front view schematically showing a conventional solenoid, and FIG. 8B is a side view thereof. DESCRIPTION OF SYMBOLS 1 ... Solenoid with a magnetic sensor 2 ... Outer frame 3 ... Air gap 4 ... Exciting coil 5 ... Coil bobbin 6 ... Plunger 7 ... Permanent magnet 9 ... Reed switch 10 ... Return spring 11 ... Work 12 Stopper

Claims (1)

(57) [Claims] An outer casing frame forming a magnetic path yoke; an exciting coil held by the outer casing frame; a plunger disposed in a hollow portion of the exciting coil so as to be able to be inserted and removed; A magneto-electric conversion element that detects a change, and a solenoid with a magnetic sensor provided so as to be able to electrically detect the operation of the plunger, wherein the side plate of the outer casing frame is cut out so as to have a predetermined gap, A solenoid with a magnetic sensor, wherein an air gap is formed in a magnetic circuit in a side plate, and the magnetoelectric conversion element is disposed near the air gap.