JP3008487U - Proximity switch - Google Patents

Abstract

(57) [Summary] [Purpose] No matter what kind of environment it is used in, it is designed so that the liquid does not penetrate and become damaged or become undetectable. A male thread portion 15 is screwed on the outer peripheral surface of the casing 11 in which a sensitive portion 13 is integrally formed on one end portion of a cylindrical peripheral wall portion 12 at the other end open portion side 14, and the inside of the casing 11 is provided with The core 31 and the circuit board 32 are provided so as to be positioned close to each other inside the sensitive portion 13, and the core 31 and the circuit board 32 are electrically connected, and the lead wire 33 connected to the circuit board 32 is connected. The internal thread portion 24 formed on the inner surface of the peripheral side portion 23 of the cap tool 21 is extended to the outside of the casing 11, the inside of the casing 11 is filled with resin, and the cap tool 21 is attached to the open side. The casing 11 is screwed into the male screw portion 15 of the casing 11.
The opening portion 14 is liquid-tightly and airtightly closed, and the lead wire 33 is inserted into the cable gland provided in the cap tool 21 to extend to the outside.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a proximity switch that electrically detects an approaching detected object.

[0002]

[Prior art]

 Conventionally, as proximity switches, those described in, for example, Japanese Utility Model Publication No. 4-6226 and Japanese Utility Model Publication No. 56-129137 are known. The one disclosed in Japanese Utility Model Publication No. 4-6226 has a structure in which a thick plate-like cover plate is fitted to the open end of a cylindrical housing, and the one disclosed in Japanese Utility Model Publication No. 56-129137 is also open. The structure for closing the end is almost the same as that described in the above publication, and in particular, a lid plate for closing the open end of the housing is fitted inside the housing and closed.

[0003]

[Problems to be solved by the device]

 In the above-described known configuration that has been conventionally known, water, oil, permeable liquid, and the like permeate through a minute gap between the housing and the lid plate in a place where the environment is showered or in a hot and humid place. For example, when coolant, skin-pass oil, cutting oil, etc. are showered on the outer surface of the proximity switch, these oils are mixed with a highly permeable chemical agent, so that the liquid from various parts of the proximity switch is Permeates, passes through the boundary between the casing and the filling resin by capillary action, and reaches the sensitive surface at the tip of the proximity switch, which extends the operating distance and causes malfunction or failure. It In addition, the liquid permeates deep into the interior over time, damaging the electronic components of the circuit board and making it unusable. Furthermore, in locations with bad environments such as those mentioned above, sludge and scale often adhere to the sensitive surface of the switch, and the iron powder that is a component of these sludge and scale causes the proximity switch to respond and cause malfunction. There are things to do. Therefore, there is a demand for a proximity switch that has chemical resistance, weather resistance, etc., that can be used for an extremely long period of time, and that has no malfunction due to sludge or scale and that is highly accurate and reliable.

[0004]

[Means for Solving the Problems]

 The present invention has been made in view of the above-mentioned conventional drawbacks and in order to meet the demands of the related art. The casing has a cylindrical peripheral wall portion integrally formed with a sensitive portion at the other end open side. A male screw portion is screwed on the outer peripheral surface of the casing, and a core and a circuit board are provided inside the casing so that the core and the circuit board are located close to each other inside the sensitive portion. Connect and extend the lead wire connected to the circuit board to the outside of the casing, fill the inside of the casing with resin and attach the cap tool to the open side, and form on the inner surface of the peripheral side part of the cap tool. The female threaded part is screwed onto the male threaded part of the casing to liquid-tightly and airtightly close the open part of the casing, and the lead wire is inserted through the cable gland provided in the cap tool to the outside. Be extended It relates to contact switch. Further, the wall thickness of the casing is made thick, and at least the wall thickness of the sensitive portion is made 3 mm or more, preferably 5 mm or more.

[0005]

[Action]

 A male screw part is screwed on the outer peripheral surface of the open side of the casing, and the female screw part formed on the inner surface of the peripheral side of the cap is screwed to securely close the open part of the casing with the cap. Even if various oils are showered, it will not penetrate into the interior and heat resistance is improved by molding the casing and cap with a heat and chemical resistant resin such as fluororesin or silicon resin. It has chemical resistance, wear resistance, etc., and can be used for a long period of time. Moreover, the wall thickness of the sensitive part is 3 mm or more, which is extremely thicker than the wall thickness of the sensitive part of the conventional general proximity switch. By doing so, even if fine iron powder such as sludge adheres to the outer surface of the sensing part, it does not respond to malfunctions, and the reliability of the detection function as a proximity switch becomes extremely high. That is, in the case of a general proximity switch with a sensing distance of 10 mm or more, if a fine iron powder of slug size is located in a gap of 3 mm or more from the core, it will not be sensitive, so like the present invention. By setting the wall thickness of the sensitive portion to 3 mm or more, malfunction due to sludge or the like can be prevented.

[0006]

【Example】

 Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a side view of a proximity switch 1 according to the present invention, and FIG. 2 is a longitudinal sectional view thereof. The proximity switch 1 includes a casing 11 and a cap 21. In the proximity switch 1 of the present invention, the sensing distance from the front surface of the core to the sensing object is 18 mm ± 10%, the sensing section wall thickness is 3 mm, and the sensing section is sensed from the outer surface. The rated operating distance, which is the distance that the body is sensitive to, is 15 mm ± 10%.

The casing 11 has a structure in which a sensitive portion 13 is integrally formed at one end of a cylindrical peripheral wall portion 12 and an open portion 14 is formed at the other end of the peripheral wall portion 12. -Molded integrally with ethylene "Teflon" (registered trademark of DuPont, USA). The wall thickness of the casing 11 is related to the sensitive distance of the proximity switch 1 in the sensitive part 13, and does not malfunction due to the influence of metal powder such as sludge and scale accumulated on the surface of the sensitive part. It is a range that does not lower the physical strength, and may be at least 3 mm or more, and the upper limit may be theoretically a range equal to or shorter than the sensitive distance, but in practice, it is limited to about 50% of the sensitive distance. Is. Further, the wall thickness of the peripheral wall portion 12 is not particularly limited, but is preferably about 2 to 10 mm due to the limitation on the volume inside the casing and the difficulty in manufacturing technique. The wall of the peripheral wall portion of the casing of the proximity switch of this embodiment is good. The thickness was 4 mm. On the outer peripheral surface of the peripheral wall portion 12 on the side of the open portion 14, a male screw portion 15 is screwed on a part of the length of the casing 11, and the cap tool 21 is attached.

The cap member 21 has a structure in which a cylindrical peripheral side portion 23 is provided on the peripheral edge of a disc-shaped lid portion 22, and is molded from poly-tetra-fluoro-ethylene as with the casing 11. A female screw portion 24 that is screwed into the male screw portion 15 of the casing 11 is screwed on the inner surface of the peripheral side portion 23. Further, a lead wire passage hole 25 is provided at the center of the lid portion 22 of the cap member 21, and a cable gland 26 for securely closing the passage hole 25 by pressing the lead wire is provided on the outer surface. As the cable gland used in this example, SKINTOP-MS (trademark) (IEC standard; IP-68 applied) manufactured by LAPP of the Federal Republic of Germany was used. The outer diameter of the casing 11 is approximately equal to the inner diameter of the peripheral side portion 23 of the cap member 21.

Inside the casing 11, a core 31 located close to the inner surface of the sensitive portion 13 and a circuit board 32 electrically connected to the coil portion of the core 31 are provided. The ends of the lead wires 33, one end of which is connected to the circuit board 32, are positioned and the inside is filled with a resin such as polyurethane or silicon.

Therefore, when the proximity switch 1 is manufactured, after the ends of the core 31, the circuit board 32, and the lead wires 33 are housed in the casing 11 and filled with resin, the cable gland 26 of the cap 21 is filled with resin. While inserting the lead wire 33, the cap member 21 is fitted to the outside of the opening portion 14 of the casing 11, and the male screw portion 15 is firmly screwed and fastened to the female screw portion 24, and the cap member 21 is fastened. The open portion 14 of the casing 11 is tightly closed. In this state, the open portion 14 of the casing 11 is closed by the cap member 21, and the male screw portion 15 and the female screw portion 24 are screwed by the length of the peripheral side portion 23 of the cap member 21. Even if the liquid is vigorously showered on the outer surface, the liquid does not penetrate into the casing 11. In addition, even if sludge adhered to the sensitive part, no malfunction occurred, and the detected object at the rated operating distance was detected normally.

In the figure, reference numeral 34 is a switch board, and the holder 35 of the proximity switch 1 is provided on the switch board 34. The holder 35 is composed of a holder element 36 which is divided into two parts. By combining the divided holder elements 36, the proximity switch 1 can be firmly held or can be separated and removed. Moreover, the position of the proximity switch 1 can be easily adjusted in the length direction by the holder 35.

The present invention has been described above based on the embodiments of the drawings. However, the present invention is not limited to the above-mentioned embodiments, and the present invention is not limited to the embodiments as long as the configuration described in the claims of utility model is not changed. But it can be done.

[0013]

[Effect of device]

 In summary, according to the present invention, a male screw portion is screwed on the outer peripheral surface of the casing in which the sensitive portion is integrally formed at one end of the cylindrical peripheral wall portion on the other end open side, and the inside of the casing is provided with The core is provided so as to be located close to the inside of the sensitive part, the circuit board is provided, the core and the circuit board are electrically connected, and the lead wire connected to the circuit board is extended to the outside of the casing. Then, the inside of the casing is filled with resin, the cap is attached to the open side, and the female screw portion formed on the inner surface of the peripheral side portion of the cap is screwed into the male screw portion of the casing to The open part is liquid-tightly and air-tightly closed, and the cable gland provided in the cap is inserted through the lead wire to extend to the outside.The casing and the cap are heat and chemical resistant. Sex tree In it has been molded into a thick-walled.

Therefore, particularly by screwing the male screw portion on the outer peripheral surface on the open end side of the casing and screwing the female screw portion of the cap member, the liquid is discharged from the minute gap between the casing and the cap member. It does not penetrate, and troubles such as damage to the internal mechanism or non-functioning do not occur. In addition, by making the wall thickness of the sensitive part of the casing 3 mm or more, the physical strength can be remarkably enhanced without deteriorating the detection function of the object to be detected, and the sludge and scale accumulated on the sensitive surface can be removed. The impact can be avoided. In addition, by molding the casing and cap with a heat-resistant and chemical-resistant resin such as fluororesin, not only are they excellent in heat resistance, chemical resistance, wear resistance, etc., but the surface is smooth and slippery. As a result, sludge and scale are less likely to adhere, and a proximity switch with high reliability can be provided even when used for a long time under any adverse environment, which is of high practical value.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a vertical sectional view of the above.

FIG. 3 is an end view in which a part of the holder is cut away.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Proximity switch 11 Casing 12 Peripheral wall part 13 Sensitive part 14 Opening part 15 Male screw part 21 Cap tool 22 Lid part 23 Circumferential side part 24 Female screw part 25 Passing hole

Claims (3)

[Scope of utility model registration request] 1. A male threaded portion is screwed on the outer peripheral surface of the casing, which is formed by integrally forming a sensitive portion at one end portion of a cylindrical peripheral wall portion, at the other end open portion side, and inside the sensitive portion, inside the sensitive portion. The core and the circuit board are provided so as to be positioned close to each other, the core and the circuit board are electrically connected, and the lead wire connected to the circuit board is extended to the outside of the casing, The inside of the casing is filled with resin and the cap is attached to the open side, and the female screw part formed on the inner surface of the peripheral side of the cap is screwed into the male screw part of the casing to make the casing open part liquid-tight. A proximity switch which is airtightly closed and has the lead wire inserted through a cable gland provided in the cap member to extend to the outside. 2. The proximity switch according to claim 1, wherein the casing and the cap member are made of a heat-resistant / chemical-resistant resin and have a thick wall, and at least a wall of a sensitive portion of the casing is 3 mm or more. 3. The proximity switch according to claim 1, wherein the heat resistant / chemical resistant resin is a fluororesin.