JPH0326607Y2 - - Google Patents

Description

[Detailed description of the invention] <Technical field of the invention> The present invention relates to a sensor for a high-frequency oscillation type proximity switch that detects the separation or approach of an object in a non-contact state using frequency changes of a coil L and a capacitor C. It is something.

<<Prior Art and Problems>> A high-frequency oscillation type proximity switch has an oscillation circuit including a detection coil, and the circuit is configured such that the detection coil serves as one element for determining the oscillation frequency.
When an object such as metal approaches the detection coil, the inductance of the coil changes, causing the oscillation frequency to change or stop oscillating, and the approach of the object is detected based on the oscillation state of this oscillation circuit. It is something.

Therefore, the detection coil is connected to the detection end of the proximity switch,
In other words, the structure is usually such that it is provided at the front end, and cables forming power lines, signal lines, etc. are drawn out from the other end, that is, the rear end.

This proximity switch has the advantage of not having any mechanical operating parts and being resistant to dust, etc. unlike light projection switches, so it is often used in harsh environments, such as when It has been incorporated into the fingertips of robots as machine tools and automatic assembly machines, and in particular has been used to check the presence or absence of metal objects at the fingertips, and the scope of its use has been expanding in recent years.

As the range of use of proximity switches expands in this way, the range of proximity switches ranging from relatively large ones to miniaturized ones are required depending on the equipment used. In addition, in response to the request, a sensor-type proximity switch that integrally incorporates a sensor section with a detection coil and a circuit section that determines whether an object is moving away or approaching based on information obtained from the sensor section. There is a sensor-separated type proximity switch in which the sensor section and the circuit section are separated. The former type of sensor-type proximity switch is integrated into a unit, which makes it easy to integrate it into equipment, but there is the problem of increased size, and the latter type of sensor-separated type proximity switch The sensor section and the detection circuit section are separated and it is necessary to connect them with a coaxial cable, so it is somewhat inconvenient to install it, but since only the sensor section can be placed in the detection section of the device, it is possible to install the sensor section on the detection section of the device. It has the advantage of being smaller in size. Furthermore, robots today are increasingly handling smaller parts year by year, and sensor-separated proximity switches, which can be miniaturized, are becoming mainstream.

As shown in FIG. 1, this type of sensor-separated proximity switch includes a sensor section 1 including a resonance circuit of a coil L and a capacitor C, an oscillation circuit 4, an amplifier 5,
It is composed of a circuit section 2 including a rectifier circuit 6 and a discrimination circuit 7, and a cable 3 connecting the sensor section 1 and the circuit section 2. When a metal object arrives at the coil L of the sensor section 1, the inductance of the coil L changes, and this change in inductance changes the oscillation state of the oscillation circuit 4, and the output of the oscillation circuit 4 is amplified by the amplifier 5. , which is further rectified by a rectifier circuit 6 and applied to a discrimination circuit 7.The discrimination circuit 7 compares the reference voltage with the voltage applied from the oscillation circuit 4, and calculates the applied voltage from the oscillation circuit 4. The presence or absence of detection of a metal object is output depending on whether the voltage is larger or smaller than the reference voltage.

As shown in FIG. 2, the structure of the sensor section 1 includes a metal main body case 9 that is open at both ends, and a detection coil L wound in a ring shape.
and a cable 3 in which a core wire 3A and a shield wire 3B are connected to lead wires 13 and 14 of the detection coil L, respectively, and the detection coil L is located near an opening at one end of the main body case 9. It is known that the main body case 9 is filled with a synthetic resin material after the cable 3 is arranged so as to be housed therein and led out from the opening at the other end.

However, in the embodiment shown in FIG. 2, the leads 13, 14 of the coil L and the cable 3
After the core wire 3A and shield wire 3B are simply connected by soldering or the like, the coil L and cable 3 are solidified and fixed with the synthetic resin material 15, so positioning between the coil L and the cable 3 is difficult. , leading to a decrease in accuracy, and in the case before solidification, both lead wires 1
3 and 14 may come into contact with each other because they are not fixed in any way, and if the resin material is filled and solidified in such a state, the insulation will be defective. Therefore, in order to insulate both lead wires, it is necessary to provide a large gap between both lead wires, resulting in a problem that the sensor section becomes large.

In addition, the connection between the lead wire 13 of the coil L and the core wire 3A of the cable 3, and the connection between the shield wire 14 and the shield wire 3B of the cable 3 is performed under an unstable condition where both can oscillate, resulting in poor workability. There was also the problem of lack of reliability.

<<Purpose of the invention>> The present invention was devised in view of the problems of the conventional proximity switch sensor. Insulation between a pair of lead wires derived from the cable and between the core wire and shield wire exposed from the cable can be easily achieved, and the connection work between each lead wire and each core wire and shield wire of the cable is easy. The purpose of the present invention is to provide a sensor structure for a proximity switch.

<<Structure and Effects of the Invention>> In order to achieve the above object, the proximity switch sensor according to the present invention has a spool wound with a detection coil inserted into a cylindrical main body case, and a detection circuit section outside the main body case. A sensor for a proximity switch, in which one end of a cable electrically connected to the coil is disposed within the case, and the spool has one end surface of the spool extending opposite to one end of the cable. the formed extension part, a conductive part provided on the outer periphery of the extension part, and an insertion hole bored along the axial direction from the end surface of the extension part, and the insertion hole includes the The core wire of the cable is inserted and fixed, one end of the lead wire of the coil and the shield wire of the cable are respectively connected to the conductive part, and the other end of the lead wire of the coil is connected to the core wire of the cable. By doing so, the detection coil and cable can be easily positioned within the main body case, and each insulation between the pair of lead wires derived from the detection coil and between the core wire and shield wire exposed from the cable is This has the effect of making it easy to connect the lead wires to the core wires and shield wires of the cable.

<<Embodiment of the invention>> Hereinafter, an embodiment of the proximity switch sensor according to the invention will be described in detail with reference to FIGS. 3 and 4. The circuit configuration of the proximity switch using the sensor in this embodiment is equivalent to the circuit configuration shown in FIG. 1, and there is no change in the circuit configuration itself. Only the parts corresponding to are shown as examples. To explain the sensor section, FIG. 3 is an axial sectional view of the proximity switch sensor 100 according to the present invention, and FIG. 4 is an exploded perspective view thereof.

In FIGS. 3 and 4, reference numeral 3 indicates that the outer periphery of the core wire 3A is covered with an insulating material 3C, and the outer periphery of the insulating material 3C is covered with a mesh-shaped shield wire 3B, and the outer periphery of the shield wire 3B is further insulated. The cable 3 is coated with material 3D and has the same structure as the cable shown in FIGS. 1 and 2. 109
Reference numeral 109 is a metal cylindrical main body case with openings at both ends, and the inner circumferential portion near the front end opening of the main body case 109 has a larger diameter than the central inner circumferential portion. 108
is a coil spool made of insulating resin material. The coil spool 108 has a coil winding part 108C around which the detection coil L is wound a predetermined number of times, and an extension part 108 extending from one end of the coil winding part.
In addition, an insertion hole 108A and an insertion hole 119 are respectively formed along the axial center in a facing relationship from the front end surface side of the spool 108 and the end surface side of the extension part 108B. It is provided. A rod-shaped core 117 made of ferrite material is fitted into the insertion hole 108A, and a core wire 3A of the cable 3 is fitted into the insertion hole 119. Also, the extending portion 108B of the coil spool 108
A conductive portion 121 is provided on the outer circumferential surface of the conductive portion 121 with conductive plating or a metal end adhered thereto. Reference numeral 120 designates a cylindrical core made of ferrite material that is fitted into the large-diameter inner peripheral portion of one end of the main body case 109 , and 115 represents an insulating resin material filled and solidified within the main body case 109 .

To assemble the sensor section 100 of the proximity switch composed of these members, first, the coil spool 10 is assembled.
With the rod-shaped core 117 inserted into the insertion hole 108A of the coil spool 108, the winding portion 108 of the coil spool 108 is
A predetermined number of detection coils L are wound around C, the lead wires 113 and 114 of the wound detection coil L are arranged to extend rearward, and the main body case 10 is
The core wire 3A of the cable 3 extending through the cable 9 is inserted into the insertion hole 119. After the lead wire 113 is wound around the core wire 3A of the cable 3 with the core wire 3A fixed to the spool 108 in this manner, the lead wire 113 is fixed to the core wire 3A by soldering.
Further, the lead wire 114 is connected to the extending portion 1 of the spool 108.
08B is soldered to a conductive part 121 provided on the outer periphery of the cable 3, and the shield wire 3B of the cable 3 is also soldered to the conductive part 121. Next, a cylindrical core 120 is attached to the large diameter portion of the inner circumference at one end of the main body case 109.
However, the main body parts 108B of the spool 108 are assembled into the main body case 109 in a state where they are fitted and inserted into the inner peripheral surface of the small diameter part of the main body case 109, and then the insulating resin material 115 is inserted into the main body case 409. It is filled and solidified.

The sensor section 100 of the proximity switch assembled in this way is used in common with the control circuit shown in FIG. 1, and when the detection coil L is energized, the magnetic flux of the detection coil L is When a metal object approaches the tip of the sensor section 100, the inductance of the detection coil L changes,
This change in inductance is detected by a control circuit.

The sensor section 100 of the proximity switch configured as described above is operated by inserting the core wire 3A of the cable 3 into the insertion hole 119 of the spool 108 and fixing the cable 3 in a fixed position relative to the spool 108. The lead wire 113 of the detection coil L wound around the core wire 3A of the cable 3 is fixed with solder after being wound around the core wire 3A of the cable 3.
Since the lead wire 114 and the shield wire 3B are fixed to the wire by soldering, the wire connection work is easy and reliability is improved.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a general circuit configuration of a proximity switch, Fig. 2 is a sectional view showing an example of a sensor section in a conventional proximity switch, and Fig. 3 is a circuit diagram showing a sensor section of a proximity switch according to the present invention. Cross section, 4th
This figure is an exploded perspective view of the sensor section shown in FIG. 1. L...Detection coil, 108...Coil spool, 109...Main case, 3...Cable, 3
A... Core wire, 3B... Shield wire, 108B...
Extension part, 119...insertion hole, 121...conductive part,
113, 114... Lead wire.

Claims (1)

[Claims for Utility Model Registration] A spool wound with a detection coil is inserted into a cylindrical body case, and one end of a cable electrically connects the coil to a detection circuit section outside the body case. The sensor for a proximity switch is arranged in a case, and the spool includes an extension part formed by extending one end surface of the spool opposite to one end of the cable, and an outer peripheral part of the extension part. and an insertion hole bored along the axial direction from the end face of the extension part, the core wire of the cable is inserted and fixed into the insertion hole, and the lead wire of the coil is inserted into the insertion hole. connecting one end and a shield wire of the cable to the conductive part, respectively;
A sensor for a proximity switch, characterized in that the other end of the lead wire of the coil is connected to the core wire of the cable.