JPH0711738U - Magnetic substance detector - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce malfunctions due to magnetic substances other than the object to be detected such as pistons and iron plates, and to manufacture at low cost. The magnet 13 is provided in the reed switch 1 in the vicinity of the end of the glass tube 12a constituting the reed switch 12 in the direction of the axis A and within a range of less than 180 degrees around the axis A.
2 and the piston 15 which is a magnetic body. Since the distance from the magnetic material other than the piston 15 becomes long, it is hardly affected by the influence and few malfunctions occur.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetic substance detector used as a proximity switch for detecting the position of a magnetic substance such as a piston of a pneumatic cylinder or a hydraulic cylinder, or an iron plate.

[0002]

[Prior art]

 Pneumatic cylinders and hydraulic cylinders have a structure in which magnets are not incorporated in the pistons. Therefore, as means for detecting the position of the piston in these cylinders, the structure shown in FIG. 4 or 5 is usually used. It is used.

That is, the magnetic substance detector 20 shown in FIG. 4 includes a substrate 21, a reed switch 22 fixedly arranged on one surface of the substrate 21, and a side and an upper side of the reed switch 22. And a lead wire 24 connected to the terminal portion of the lead piece of the reed switch 22. The reed switch 22 is provided with a magnet 23 whose length in the axial direction is substantially the same as the length of the reed switch 22. Has been done. More specifically, the magnet 23 is provided with first and second magnets 23a, which are fixedly arranged on the substrate 21 substantially parallel to the axial direction of the reed switch 22 on both sides of the reed switch 22. 23b and a third magnet 23c arranged above the reed switch 22 so as to be bridged between the first and second magnets 23a and 23b.

In the magnetic material detector 30 shown in FIG. 5, the positional relationship of the substrate 31 and the reed switch 32 is the same as that shown in FIG. 2, but the magnet 33 has a side edge portion. Two magnets arranged in an inclined manner so that one is located near the top of the glass tube 32a that constitutes the reed switch 32, and the other is located on the substrate 31 that is slightly apart from the side of the reed switch 32. 33a and 33b are used. In addition, 34 is a lead wire.

[0005]

The magnetic body detectors 20 and 30 described above are shown in FIGS. 4 and 5 from the surface opposite to the surface of the substrates 21 and 31 on which the read switches 22 and 32 are arranged. The positions of the pistons 25, 35, which are magnetic bodies and move in the X direction, are detected so that the pistons 25, 35 move in the X direction so as to pass through a position slightly separated in the upper Z direction. That is, since the pistons 25, 35 and the magnets 23, 33 form a magnetic circuit via the reed switches (not shown) of the reed switches 22, 32, if the operating magnetic field of the reed switches 22, 32 is reached. The reed switches 22 and 32 operate to detect their positions.

However, each of the magnetic substance detectors 20 and 30 includes a reed switch 22 and 32 which is a detecting body, magnets 23 and 33 which are magnetic sources, and pistons 25 and 35 which are detected bodies. Due to the positional relationship among the three, the sensitivity to not only the pistons 25 and 35 but also magnetic bodies other than the pistons 25 and 35 acting on the side where the magnets 23 and 33 are arranged is considerably high. Therefore, even if the pistons 25 and 35 are not close to each other, there is a problem that the lead switches 22 and 32 are turned on and malfunctions are likely to occur. In addition, since each of the magnets 23 and 33 is configured by combining a plurality of magnets in order to improve the sensitivity of the reed switches 22 and 32, there is a problem that material cost and assembly cost are increased.

The present invention has been made in order to solve the above-mentioned problems, and reduces malfunctions due to magnetic substances other than the detected substance such as a piston and an iron plate, and magnetic substance detection that can be manufactured at low cost. The purpose is to provide a container.

[0008]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, a magnetic substance detector of the present invention has a reed switch fixedly arranged on a substrate made of a non-magnetic material, and a magnet held by the substrate and driving the reed switch. In a magnetic substance detector that detects the position of an object to be detected that is made of a magnetic substance that moves on the opposite side of the reed switch across the substrate, the magnet is located near the axial end of the glass tube that constitutes the reed switch. And is arranged between the reed switch and the magnetic body within a range of less than 180 degrees around the axis.

[0009]

[Action]

 When the detected object moves and reaches the operating magnetic field of the reed switch, the reed switch turns on and functions as a proximity switch.

[0010]

【Example】

 Hereinafter, the magnetic detector of the present invention will be described in more detail with reference to an embodiment shown in the drawings. In the figure, reference numeral 10 is a magnetic substance detector of the present embodiment, which has a substrate 11, a reed switch 12, a magnet 13, and a lead wire 14.

The substrate 11 is made of a non-magnetic material such as a plastic material. The board 11 is composed of a printed board 11a to which the reed switch 12 is attached, and a magnetic board 11b on which one surface of the printed board 11a is supported and a magnet 13 is fixedly arranged. The shapes of the printed board 11a and the magnet mounting board 11b are not limited.

The reed switch 12 has terminal portions 11c and 11d provided at regular intervals on a printed circuit board 11a which constitutes the substrate 11, and ends of lead pieces 12b and 12c protruding from both ends of the glass tube 12a. It is connected and arranged. A lead wire 14 is also connected to the terminal portions 11c and 11d.

The magnet 13 is formed in a substantially rectangular flat plate shape, and the size thereof is shorter than one half of the length in the axial direction of the glass tube 12 a of the reed switch 12. The size of the magnet 13 can be reduced in this way because of the relationship with the arrangement position. That is, the magnet 13 is first arranged near the end of the glass tube 12a that constitutes the reed switch 12. This is because the lead switch 12 magnetically approaches the ON state in the normal state by disposing it near the end of the glass tube 12a, so that the sensitivity of the lead switch 12 is improved.

Further, the magnet 13 is a piston which is a detected body which passes through the reed switch 12 and the opposite surface side of the magnet mounting substrate 11b within a range of less than 180 degrees around the axis A of the reed switch 12. It is arranged between 15 and. In order to dispose the magnet 13 at such a position, in this embodiment, as described above, the magnet mounting board 11b for supporting the print board 11a on one surface together with the reed switch 12 is engraved on the one surface side. It is embedded in the groove 11e.

To explain the above with reference to the side view shown in FIG. 2, the lead switch 12 is arranged at the uppermost position in the drawing, and the magnet 13 is arranged below the axis A thereof. The positional relationship is such that the piston 15 moves. However, as shown in the front view of FIG. 3, the magnet 13 may be below any side of the reed switch 12 or directly below it as long as it is within a range of less than 180 degrees around the axis A.

As the magnet 13, various magnet materials such as a ferrite magnet can be used. However, since it can be used in an extremely small shape as described above, a relatively expensive rare earth magnet is used. But it's worth the cost. Rare earth magnets are preferable because they have a small reversible temperature coefficient of the residual magnetic flux density, so the influence of ambient temperature is extremely small and the operating temperature range is wide.

In the magnetic material detector 10 of the present embodiment, when the piston 15 moves in the X direction in FIG. 1 and reaches the detection position B, a part of the magnetic force lines emitted from the magnet 13 causes the reed switch 12 to reed 12b, 12c, and returns to the magnet 13 via the piston 15. As a result, the reed switch 12 is turned on.

Even when a magnetic body other than the piston 15 that is the object to be detected approaches from the opposite side of the piston 15 (that is, the side opposite to the Z direction in the figure), the magnet 13 is placed in the above-described position. Since it is disposed, the distance from the magnetic substance other than the piston 15 is long, and thus it is less affected by the conventional magnetic substance detector.

The magnetic substance detector 1 of the present invention is not limited to the above-described embodiment. In the above-described embodiment, the printed circuit board 11a for mounting the reed switch 12 as the substrate 11 and the magnet mounting plate 11b for holding the magnet 13 are used, but one reed switch 12 and the magnet 13 are provided. It may be supported by the above substrate and arranged in the above-mentioned positional relationship.

[0020]

[Effect of device]

 According to the magnetic substance detector of the present invention, malfunctions due to magnetic substances other than the detected substance such as the piston and the iron plate are small. Moreover, since the size of the magnet is small, it can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a magnetic substance detector according to the present invention.

FIG. 2 is a side view of the embodiment.

FIG. 3 is a front view of the embodiment.

FIG. 4 is a perspective view showing an example of a conventional magnetic substance detector.

FIG. 5 is a perspective view showing another example of a conventional magnetic substance detector.

[Explanation of symbols]

 10 Magnetic Substance Detector 11 Substrate 12 Reed Switch 13 Magnet 14 Lead Wire 15 Piston 20 Magnetic Substance Detector 21 Substrate 22 Reed Switch 23 Magnet 30 Magnetic Substance Detector 31 Substrate 32 Reed Switch 33 Magnet

Claims (2)

[Scope of utility model registration request] 1. A reed switch fixedly mounted on a substrate made of a non-magnetic material and a magnet that is held by the substrate and drives the reed switch, and moves on the opposite side of the reed switch across the substrate. In a magnetic substance detector for detecting the position of an object to be detected made of a magnetic substance, the magnet is in the vicinity of an end of the glass tube forming the reed switch in the axial direction and less than 180 degrees around the axial center. The magnetic substance detector is arranged between the reed switch and the magnetic substance within the range of. 2. The magnetic substance detector according to claim 1, wherein the magnet is a ferrite type or rare earth type magnet.