KR20220040953A - Magnetic field shielding element for magnetic sensor which senses magnets in the body of cylinder - Google Patents

Abstract

According to an embodiment of the present invention, provided is a magnetic field shielding element for a magnetic sensor that detects a magnetic material in a cylinder body. The magnetic field shielding element for a magnetic sensor is to protect a magnetic sensor for detecting the magnetic field of a magnetic material coupled to a piston inside a cylinder from the external magnetic field. The shielding element comprises: a main body part for enclosing the magnetic sensor located therein; and an extension part extending along a surface of a cylinder body from an end of the main body part, wherein the extension part is coupled to the surface of the cylinder body to come in close contact therewith. According to the present invention, in order to smoothly maintain the operation of the piston in the cylinder body, it can be expected that the magnetic sensor for detecting the operating state of the piston detects only the magnetic field generated by the magnetic material installed in the piston in the cylinder body.

Description

Magnetic field shielding element for magnetic sensor which senses magnets in the body of cylinder

The present invention relates to a magnetic field shield for a magnetic sensor that detects a magnetic body in a cylinder body, and by implementing a magnetic field shield so that the magnetic sensor for detecting a magnetic body in the cylinder body is not affected by an external magnetic field, the magnetic sensor is a cylinder By effectively detecting only the magnetic material in the main body, it is possible to detect the abnormality of the piston in the cylinder without error.

An unmanned production facility system based on an automated facility is established in a product production plant that assembles products or manufactures products by other methods on a manufacturing line such as the automobile industry. At this time, pneumatic or hydraulic cylinders ( 10) is often used. As shown in the schematic diagram of FIG. 1 , the cylinder body 11 includes a magnetic body 13 , and the magnetic body 13 is a means for determining the position of the piston in the cylinder body 11 . The magnetic sensor 14 detects the magnetic field output from the magnetic body 13 , so that it is possible to easily grasp the position of the piston 12 in the cylinder body and whether the piston 12 is properly operated at the position.

The magnetic body inside the cylinder body penetrates the metal body constituting the cylinder body and the magnetic field is detected by a sensor such as a sensor provided outside, and a magnetic field of about 10 mT is usually measured on the surface of the cylinder body. For this magnetic field detection, for example, a semiconductor-type Hall sensor with high sensitivity to which the Hall effect is applied is used as an external measurement sensor, and the sensor adopts a sensor that can detect if a magnetic force of at least 4mT is maintained. The Hall effect refers to a phenomenon in which a potential difference occurs by generating positive (+) and negative (-) charges on the side of the conductor when a magnetic field is applied to a conductor through which current is flowing.

As a method of detecting the vertical movement of the piston in the cylinder body, there are a method of detecting by wire, and a method of wirelessly processing a detection signal after detecting the vertical movement of a magnetic material attached to the piston with a magnetic sensor.

In detecting a magnetic signal by applying such a magnetic sensor, there are other equipment that use a magnetic field or generate a magnetic field in the manufacturing line, even though only the magnetic material in the cylinder body must be detected. In the case where it is installed as a result, it acts as an external obstacle to the detection of the magnetic body in the cylinder body.

For example, as shown in FIG. 2, there are many cases in which an electric welding machine necessary for product assembly is installed and used around the cylinder. According to the equipment, welding is performed unattended. However, in the same equipment, a strong magnetic field is formed during welding, and the magnetic field is mainly formed in the region of the welding rod 22 and the welding rod support 21 shown in FIG. 2 .

This magnetic field affects the magnetic sensor for detecting the magnetic field of the magnetic body in the cylinder body, and as a magnetic sensor, it also detects an unnecessary magnetic field, ultimately causing a malfunction of the magnetic sensor.

Such an electric welding machine uses direct current and uses a large current of 7~8KA on average and about 11KA at maximum. It is formed in the form of a closed curve (FIG. 3). The magnetic field strength due to infinite current can be obtained based on Ampere's circular law, which defines that the linear integral of the magnetic field H for any closed curve is equal to the current I passing through the closed curve. The calculation process is as follows.

∮

The strength of the magnetic field due to an infinite linear current is 2πr because the line integral of dl is the circumference.

(여기서,

)

(here,

)

Here, R is the distance between the linear current and the strength H of the magnetic field, and it can be seen that the strength of the magnetic field is inversely proportional to the distance.

The strength of the magnetic field due to a finite-field linear current can be obtained using the Biot-Savard law.

의 관계로부터,If the magnetic field strength H is expressed as the magnetic flux density B,

from the relationship of

(

)

(

)

It can also be expressed as

When the maximum current of the DC electric welding machine is 11kA, the predicted magnetic field according to the distance is shown in Table 1 below. There may be differences.

distance 1 cm 5cm 10cm 20cm 30cm 50cm 1m mT 220 44 22 11 7 4 2.2

In other words, the magnetic field generated from the electric wire of the electric welding machine is not a magnetic field caused by the up-and-down movement of the piston in the cylinder body. There was a problem in that an error of detecting that the operation was performed even though it was not done occurred.

The present invention has been devised to solve the problems of the prior art described above, and the present invention provides a magnetic sensor for detecting the operating state of the piston in a magnetic body installed on the piston in the cylinder body in order to smoothly maintain the operation of the piston in the cylinder body. An object of the present invention is to provide a magnetic field shield for a magnetic sensor that detects a magnetic body in a cylinder body to detect only a magnetic field generated by the

The present invention in order to achieve the above object, in the shield for protecting the magnetic sensor for detecting the magnetic field of the magnetic material coupled to the piston inside the cylinder from the external magnetic field, the shield, the magnetic sensor located inside body part for; and an extension portion extending along the surface of the cylinder body from the end of the body portion, wherein the extension portion is coupled to the surface of the cylinder body in close contact with the magnetic sensor for sensing a magnetic body in the cylinder body Provide magnetic shielding.

It is preferable that the cross-section of the body portion of the shielding member is of a housing type so as to surround the magnetic sensor.

It is preferable that a second shield having a size that can wrap the shield is further included.

It is preferable that the second shielding member has the same shape as the shielding member or has a housing type surrounding the shielding member.

The magnetic sensor is installed on the surface of the cylinder body corresponding to the position of the movement limit of the piston, and when at least two of the magnetic sensors are installed at the position of the same movement limit of the piston, the shielding part corresponds to the number of magnetic sensors It is preferable to install each so as to correspond.

Preferably, the magnetic sensor is installed on the surface of the cylinder body corresponding to the position of the movement limit of both ends of the piston so that it can be checked whether the piston is normally moved to the position of the movement limit of the both ends.

The length of the extension is preferably in the range of 0.5 to 5 mm.

According to the present invention as described above, in order to smoothly maintain the operation of the piston in the cylinder body, it can be expected that the magnetic sensor for detecting the operating state of the piston detects only the magnetic field generated by the magnetic material installed on the piston in the cylinder body. there is.

In addition, by allowing the magnetic sensor to detect only the magnetic field generated by the magnetic material installed on the piston in the cylinder body, the effect of accurately detecting whether the piston is malfunctioning can be expected.

1 is a view showing a cylinder to which a magnetic sensor is attached.
2 is a schematic diagram showing an electric welding machine.
3 is a diagram illustrating Ampere's circular law.
4 is a diagram illustrating a structure in which a shield having a circular cross section surrounds the magnetic sensor.
5 is a diagram illustrating a structure in which a shield having a semicircular cross-section surrounds the magnetic sensor.
Figure 6 is a schematic diagram showing the state that the shield of Figure 5 is attached to the surface of the cylinder body and the effect by the magnetic field of the electric welding machine.
7 is a view showing a structure in which the shielding sphere of the present invention surrounds the magnetic sensor.
FIG. 8 is a schematic diagram showing the state that the shield of FIG. 7 is attached to the surface of the cylinder body and the effect of the magnetic field of the electric welding machine.
9 is a perspective view of FIG. 7 ;
10 is a view showing a form in which the second shielding sphere is wrapped around the shield of the present invention.
11 is a schematic diagram showing the arrangement of a magnet and a magnetic sensor prepared to measure the level of shielding by the shielding device when the shielding device of the present invention is used.

Hereinafter, with reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part "includes" a certain element, it means that other elements may be further included, rather than excluding other elements, unless otherwise stated.

In addition, terms such as "... unit" and "... group" described in the specification mean a unit that processes at least one function or operation.

At least two magnetic sensors 14 of the present invention may be configured on the surface of the cylinder body corresponding to the same position among the positions of the movement limit of the piston. At this time, each magnetic sensor 14 has an opposite position. In addition, magnetic sensors 14 may be installed respectively at the position of the limit of movement of the proximal and distal portions of the piston. This is indicated in FIG. 1 . Thereby, it can be confirmed whether the piston is normally moved to the position of the movement limit of the proximal part and the distal part by the magnetic sensor 14.

)이 커서 자기 차폐에 적합하며, 철, 니켈, 코발트, 규소강, 포멀로이 등이 있다. 본 발명에서 차폐구는 비투자율이 7000 이상인 규소강판이나 비투자율이 5000 이상인 철을 사용할 수 있는데, 반드시 이에 한정되는 것은 아니다. The present invention is a magnetic field shield for a magnetic sensor that detects whether a cylinder piston is operating, and a ferromagnetic material is usually used to shield the magnetic field. When a ferromagnetic material surrounds the outside of the magnetic sensor, the magnetic sensor cannot detect a magnetic field due to a shielding characteristic. A ferromagnetic material can be characterized by its relative permeability,

) is large and suitable for magnetic shielding, and there are iron, nickel, cobalt, silicon steel, and formalloy. In the present invention, the shield may use a silicon steel sheet having a relative magnetic permeability of 7000 or more or iron having a relative magnetic permeability of 5000 or more, but is not necessarily limited thereto.

In order to shield the magnetic field, the structural shape of the magnetic shield for inducing the flow of the magnetic field is an important element, which is the core of the present invention.

As shown in FIG. 4 , if the entire direction of the magnetic sensor 14 is surrounded by the ferromagnetic shield 30 , the magnetic shielding is good, but the magnetic sensor 14 detects the magnetic field generated when the piston in the cylinder body moves up and down. Since it cannot be done, it cannot be applied to the real environment.

5 and 6, when the magnetic sensor 14 is surrounded by a ferromagnetic shield 40 in the form of a housing, for example, a semi-circle or semi-ellipse, the magnetic shielding is to some extent, but due to the electric welding machine, The generated strong magnetic field is not shielded. The reason is that the magnetic sensor 14 inside the ferromagnetic material 40 is affected by the magnetic field that continues at the end of the semi-circle or semi-elliptical ferromagnetic material.

In the present invention, in order to improve this, as shown in FIGS. 7 and 8, the structure of the ferromagnetic shield 100 surrounding the magnetic sensor 14 is configured in the form of a housing, that is, for example, in a semi-circle or semi-ellipse shape. , by configuring the extension 102 to extend the end of the ferromagnetic shield 100 in the horizontal direction, the magnetic field flows in the direction of the extension 102 while riding on the main body 101 of the shield 100 Because it exits, the influence of the magnetic field on the magnetic sensor 14 is absent or very insignificant. 9 is a perspective view of the shield 100 of FIG. 7 . Here, the length of the extension 102 is preferably in the range of 0.5-5 mm. This is because there is an advantage of being able to sufficiently achieve the attenuation effect of the magnetic field and easy handling at the same time.

As in the present invention, when an omega letter (Ω)-shaped shield is applied and attached to the cylinder body 11 to be in close contact, the magnetic sensor 14 is weak generated when the piston 12 in the cylinder body 11 moves up and down. The magnetic field can be detected by the magnetic sensor 14 and recognized as an operation signal, and since other magnetic fields cannot affect the magnetic sensor 14, the cylinder operation state can be monitored without error.

As an additional embodiment, as shown in FIG. 10, the shielding sphere of the omega character shape as described above primarily protects the magnetic sensor 14 and is sized to surround the shielding sphere 100, When the shield is further wrapped using the second shield 103 of a ferromagnetic material provided at a location spaced apart from the shield by a predetermined distance, it becomes a double shielding structure, thereby further improving the shielding performance against the magnetic field. The shape of the second shielding sphere 103 may be the same as that of the shielding sphere 100 or may be a simple enclosure shape.

As a result of applying the second shield 103, the magnetic field introduced from the outside did not affect the shield 100, which is that the magnetic force line flowing in through the second shield 103 eventually passes through the shield 100. It can be explained through the phenomenon of being discharged back to the outside.

That is, the performance test of the shield was conducted. After the magnetic sensor 14 was wrapped with the semi-circular shield 40 and the omega-shaped shield 100 according to the present invention, respectively, a neodymium magnet generating a strong magnetic field ( As a result of conducting an experiment by placing a magnetic field 200 mT) near it, in the case of the semi-circular shield 400, the magnetic sensor 14 provided inside the shield 40 sensed the magnetic field, whereas the omega shape of the present invention The magnetic field was not detected in the shield 100 of the (Ω) structure.

In addition, when applied to the field using an electric welding machine, the magnetic sensor 14 sensed the magnetic field in the semi-circular shield 40, whereas in the case of the omega-shaped (Ω) shield according to the present invention, the magnetic field was not detected. didn't Therefore, it was confirmed that the shield 10 according to the present invention has a structure suitable for shielding an external magnetic field generated in the process of welding with an electric welding machine.

11 is a schematic diagram showing the arrangement of a magnet and a magnetic sensor prepared to measure the level of shielding by the shielding device when the shielding device of the present invention is used. The magnet was a neodymium magnet, but the type of magnet is not particularly limited.

According to the schematic diagram above, the shielded magnetic field is summarized and shown in the table below.

shield 2nd shield Measurement result - - 74.0 mT Semi-circular silicon steel - 20.4 mT Omega-type silicon steel - 11.7 mT Semi-circular silicon steel 2 tons of steel 6.1 mT Omega-type silicon steel 2 tons of steel 5.4 mT Semi-circular silicon steel 3 tons of steel 5.0 mT Omega-type silicon steel 3 tons of steel 4.0 mT

As can be seen from the table above, as a result of using the shield 100 according to the present invention, it can be seen that the magnetic field is reduced by half compared to the case of using a conventional semi-circular silicon steel as a shielding material. In addition, when the second shielding hole 103 was applied, the reduction was further reduced, and even when the second shielding hole 103 was applied, the shielding effect was excellent even when a semi-circular silicon steel was used.

It should be noted that the above-described embodiment is for illustrative purposes only, and not for its limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

10: cylinder 14: magnetic sensor
30: circular shielding sphere 40: semi-circular shielding sphere
100: omega type shield 101: body part
102: extension 103: second shielding port

Claims (7)

In the shield for protecting the magnetic sensor for sensing the magnetic field of the magnetic body coupled to the piston inside the cylinder from an external magnetic field, the shield,
a body part for enclosing the magnetic sensor located therein; and
an extension extending along a surface of the cylinder body from an end of the body portion;
consists of,
The extension portion is a magnetic field shield for a magnetic sensor for detecting a magnetic body in the cylinder body, characterized in that coupled to be in close contact with the surface of the cylinder body. According to claim 1,
A magnetic field shield for a magnetic sensor for detecting a magnetic body in a cylinder body, characterized in that the body portion of the shield has a cross-section to surround the magnetic sensor. According to claim 1,
A magnetic field shield for a magnetic sensor for sensing a magnetic body in the cylinder body, characterized in that it further includes a second shield having a size that can wrap the shield. 4. The method of claim 3,
The second shielding sphere has the same shape as the shielding sphere, or a magnetic field shield for a magnetic sensor for sensing a magnetic body in the cylinder body, characterized in that it has a housing type surrounding the shielding sphere. According to claim 1,
The magnetic sensor is installed on the surface of the cylinder body corresponding to the position of the movement limit of the piston, and when at least two of the magnetic sensors are installed at the position of the same movement limit of the piston, the shielding part corresponds to the number of magnetic sensors A magnetic field shield for a magnetic sensor that detects a magnetic body in the cylinder body, characterized in that they are installed to correspond to each other. According to claim 1,
The magnetic sensor is installed on the surface of the cylinder body corresponding to the position of the limit of movement of both ends of the piston so that it can be checked whether the piston is normally moved to the position of the limit of movement of the proximal part and the distal part. Magnetic field shield for magnetic sensor that detects magnetic resistance. According to claim 1,
A magnetic field shield for a magnetic sensor for detecting a magnetic body in the cylinder body, characterized in that the length of the extension is in the range of 0.5 to 5 mm.

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