JP2508120B2 - Limit switch - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to, for example, an unmanned factory production line,
The present invention relates to a limit switch used for detecting various objects such as a product to be processed transferred to a predetermined position and automatically operating a processing machine, detecting various objects, and operating various machines and devices.

(Prior art and its problems) When the limit switch is continuously used in an environment in which liquid such as water is scattered, the liquid that has entered through the gap of the casing gradually accumulates, and finally the contact mechanism. There was a problem that the contact was short-circuited and the operation failure suddenly occurred and the machine whose operation was controlled runs away or is damaged. This has been a major cause of downtime and productivity because the production line has to be stopped even if the machine runs away from runaway or damage.

(Object of the Invention) The present invention has been made in view of the above problems, and an object of the present invention is to provide a switch that can prevent malfunction due to liquid intrusion into the casing.

(Structure and Effect of the Invention) In order to achieve such an object, the present invention provides a limit switch with a through hole at an appropriate position, and
A box-shaped casing having an opening formed in one side surface, and an actuating mechanism mounted at a position having the through hole on the casing surface and displacing by contact with an external object,
A switch mechanism provided in the casing and operating in conjunction with the actuating mechanism through the through hole; a liquid intrusion detection mechanism provided in the casing and having at least a pair of electrode plates; and equipped in the casing. And an alarm mechanism for performing an alarm operation in response to an input of a liquid detection signal from the liquid intrusion detection mechanism, wherein the switch mechanism and the liquid intrusion detection mechanism are provided in the casing through the opening of the casing. The electrode plate is inserted and arranged, the opening is closed by a lid, and the electrode plate is arranged so as to cover an inner surface of a side surface portion of the casing that faces the one side surface portion.

According to this configuration, if the side surface portion provided with the opening portion of the casing is used so as not to be located below, the liquid immediately enters the casing and accumulates in the lower portion regardless of the direction used. Then, the liquid intrusion detection mechanism outputs the liquid detection signal prior to the connection portion of the switch portion, and the alarm mechanism issues an alarm.

In the above, for example, when the side surface portion facing the side surface portion provided with the casing opening is used so as to face downward, any part of the electrode plate positioned so as to cover the side surface portion is electrically connected. , On the other hand, when the side surface portion not provided with other openings is used as the lower side, the peripheral edge portion of the electrode plate located near the inner surface of the side surface portion becomes conductive, and Thus, if the side surface of the casing provided with the opening is not positioned below, no matter which direction it is used, when the liquid enters the casing, the electrodes are immediately connected to each other. It is a thing.

Therefore, according to the present invention, when the liquid invades and collects in the casing, the liquid intrusion detection mechanism is activated and an alarm is issued before the connection portion of the switch is short-circuited by the liquid, and an appropriate countermeasure is taken based on this alarm. By doing so, it became possible to reliably prevent sudden malfunction of the switch due to liquid intrusion.

In particular, since liquid intrusion can be detected in all directions other than one direction during use, it can be used in an appropriate direction corresponding to the installation site, which is very convenient.

(Description of Embodiments) Hereinafter, the present invention will be described in detail based on embodiments illustrated in the drawings. 1 is an exploded perspective view of the switch of the present invention, FIG.
The figure is a longitudinal sectional view and a partially cutaway front view.

In these drawings, reference numeral 1 is a metal casing, a through hole 2 is provided in the upper surface thereof, and a mounting port 3 as an opening is provided in the front surface. Mounting blocks 5 for mounting an actuating body (actuator) 4 as an actuating mechanism are attached to the upper surface of the casing 1 by screws 6 respectively, and the actuating body 4 is laterally fitted into the mounting block 5 as shown in FIG. It is fixedly attached to the end of the rotating rod 7 shown. Reference numeral 8 denotes a cylindrical pressing member, which is a mounting block 5
Inside, the flat portion 9 of the rotating rod 7 is pressed from above by the force of the coil spring 10 mounted inside, and the rotating rod 7 and the actuating body 4 are positioned at a predetermined rotation position. 11 is a plunger, and the upper surface 12 is the flat portion 9 of the rotating rod 7.
It comes into contact with the lower surface of the and is moved up and down as the rotating rod 7 rotates.

As shown in the cross-sectional view of FIG. 5, tapered surfaces 9a (taper α degree) that decrease outward are provided on both side edges of the upper surface of the flat portion 9 of the rotating rod 7 corresponding to the pressing member 8. . When the flat portion 9 is in the horizontal state, the horizontal surface 9b of the flat portion 9 contacts the lower surface of the pressing member 8, and when the flat portion 9 exceeds the rotation angle of α degrees from the horizontal state, one tapered surface
9a contacts the lower surface of the pressing member 8. With this configuration, the spring force (return load) exerted on the actuating body 4 side of the coil spring 10 is
Since the rotational moment is larger when the contact position of the pressing member 8 is the tapered surface 9a, it is larger than when the contact position is the horizontal surface 9b. Therefore, when the contact of the object with the actuating body 4 is released and the switch mechanism described later is restored, the taper surface 9a is first pushed by the pressing member 8 and then the horizontal surface 9b is pushed. The return load applied to the 4 side is reduced on the way. The above-mentioned tapered surface 9a structure constitutes a return load reducing means.

A switch unit 13 is composed of a switch main body 14 as a switch configuration and a water (liquid) intrusion detection mechanism 15.

The switch body 14 is vertically arranged in the resin base 16.
A pair of fixed contacts 17 are fitted and fixed, and a movable body 18 is provided so as to move up and down between the two pairs of fixed contacts 17. The pair of fixed contacts 17 located on the lower stage are integrally provided with the protrusions 17a. Also resin base 1
As shown in Fig. 6, two pairs of fixed contacts 17 are provided on the rear surface of the 6
A fitting connector portion 19 of the connector terminal is provided so as to face the. The movable body 18 has two stages of fixed contacts in two stages.
Movable contacts 20 corresponding to 17 are attached so as to be interlocked via respective leaf springs 20a. The movable body 18 is biased upward by a coil spring 21 attached to the lower end, and an adjusting screw 22 is attached to a portion projecting from the inside of the resin base 16 at the upper end, and the upper surface of the adjusting screw 22 has the plunger described above.
It is designed to abut the lower end of 11. Reference numeral 23 denotes a transparent cover, which is provided so as to cover the movable body 18 and the like, and a lower portion is provided with a pair of openings 24 into which the respective protruding portions 17a of the lower fixed contacts 17 are fitted and projected. The protrusion 17a projects outward from 24.

As shown in FIG. 6, each mounting space 17b in which the fixed contacts 17 of the resin base 16 are provided is configured such that the lower one is wider than the upper one in the vertical direction. With this configuration, when the movable body 18 is in the lowered position (the one shown in FIG. 6 is in the raised position and the contacts are in contact), the movable springs 20a are urged upward by the leaf springs 20a to move the movable contacts 20 to the upper position in the mounting space 17b. The contact mechanism located at a distance from each fixed contact 17 is larger than the contact mechanism located at the lower stage than the contact mechanism located at the upper stage. On the other hand, the displacement of the leaf spring 20a is caused by the movement of the leaf spring 20a in the vertical direction as the leaf spring 20a moves vertically.
Occurs when the locking position to the position exceeds the movable contact 20 height position. Therefore, when the movable body 18 rises and returns with the return operation of the actuating body 4, the distance between the movable contact 20 and the fixed contact 17 is large, and the position where the leaf spring 20a is locked to the movable body 18 and the movable contact 2
0 The displacement of the leaf spring 20a is delayed in the lower contact mechanism where the distance between the height positions is longer than in the upper contact mechanism, and thus the contact disconnection is delayed. .

The water intrusion detection mechanism 15 is composed of a pair of electrode plates 25 and an insulating sheet 26 interposed therebetween, and three fitting holes 27 are provided in each of the electrode plates 25. Is provided with a fitting hole 28 and notches 29 on both sides of the upper part, and fitting projections 30 projecting at opposite positions on the surface of the resin base 16 are fitted into these parts to form electrodes. Plate 25
The insulating sheet 26 is attached to the surface of the transparent cover 23. Further, a pressing cover 32 also provided with a fitting hole 31 so as to press the electrode plate 25 located on the outer surface.
Is attached and the whole is fixed by the pressing cover 32.

Each of the electrode plates 25 is maintained in a separated state with a predetermined interval by interposing an insulating sheet 26 therebetween. Further, each of the electrode plates 25 is provided with openings 33 on the opposite sides of the lower part, and openings 34 are also provided on both sides of the lower part of the insulating sheet 26. And the opening 24 of the transparent cover 23
One of the protrusions 17a protruding from each contacts the adjacent electrode plate 25, and the other protrusion 17a contacts the electrode plate 25 located far away through the opening 33 of the adjacent electrode plate 25 and the opening 34 of the insulating sheet 26. It is supposed to do. The insulating sheet 26 only needs to have the opening 34 on one side,
Further, the opening 33 is not required in the electrode plate 25 located at a distance, but each opening is provided so that parts can be shared.

When mounting the switch unit 13 in the casing 1, the switch cover 13 is pushed inward from the mounting opening 3 so that the presser cover 32 side is located at the back side of the casing 1. The push-in is projected to both inner side surfaces of the casing 1. In the guide portion 35 provided, the resin base 16, the electrode plate 25, the insulating sheet 26,
A guide portion 36 provided in a concave shape on each side of the pressing cover 32 is guided. With the switch unit 13 installed in the casing 1, the adjusting screw 22 is rotationally adjusted to adjust the rotational angle of the operating body 4.

The circuit unit 37 includes a printed circuit board 38 and a mounting block 39 for the printed circuit board 38, and various circuit elements described later are mounted on the printed circuit board 38.
Is an LED as an alarm mechanism which is one of the circuit elements. Two pairs of connector terminals 41 connected to predetermined portions of the circuit of the printed circuit board 38 are attached to the opposite surface of the printed circuit board 38. The printed circuit board 38 is fitted and fixed in the mounting block 39 so that its circuit surface side faces the mounting block 39, and at that time, the mounting block
An end of the output terminal 42 attached to the side of the printed board 38 that does not face the printed board 38 is connected to a predetermined portion of the printed board 38. Also, in this installation, LED4
The number 0 is stored in the cylindrical portion 43 of the mounting block 39.

The circuit unit 37 is attached to the resin base of the switch unit 13 that is pushed into the casing 1.
This is done by pushing the connector terminals 41 into the fitting connector portions 19 of the 16 so as to push them into the casing 1. Also in this case, the dent-shaped guide portion 44 provided on the side surface of the mounting block 39 is used for the casing 1 Is guided by the guide portion 35 of.

45 is a lid, which is screwed into the mounting opening 3 through the packing 46.
It is attached by 47. The lid 45 is provided with a confirmation window 48 for the LED 40, and a nameplate mounting portion 49 is formed in the center.

Next, a circuit configuration used in the switch mechanism of this embodiment will be described with reference to FIG.

Reference numerals 101 and 102 denote first and second switch portions that turn on / off in conjunction with the above-described actuating body 4 and output on / off signals S1 and S2, respectively. The water intrusion detection switch 15a configured by the electrode plate 25 is connected. First switch 1
Reference numeral 01 denotes a fixed contact 17 located at the upper stage and a movable contact 20 corresponding to the fixed contact 17, and the second switch 102 has a fixed contact 17 located at the lower stage and a movable contact 20 corresponding to the fixed contact 17. It is composed by. Then, as described above, the second switch section 102 is configured to return later than the first switch section 101.

Reference numeral 103 denotes a detection pulse (first rising detection pulse S3) corresponding to the rising edge of the on / off signal S1 and a detection pulse (first And a detection pulse corresponding to the rising edge of the on / off signal S2, which is supplied with the on / off signal S2 of the switch contact from the second switch section 102 The second input circuit outputs a (second rising edge detection pulse S4) and a detection pulse corresponding to a falling edge (second falling edge detection pulse S6).

Reference numeral 105 denotes a second rising edge from the second input circuit 104 when the timer operation is started in response to the first falling edge detection pulse S5 and the second switch section 102 is normal after the timer operation starts. It has a time-up time T that is set longer than the period until the falling detection pulse S6 is given, and outputs a time-up signal S7 when the time is up and detects the second falling edge that is given before the time-up. The timer circuit resets the timer operation in response to the pulse S6.

106 is a first D to which the output of the first input circuit 103 is applied.
In response to the time-up signal S7 (clock) provided from the timer circuit 105 when the outputs of the flip-flop 106a and the second input circuit 104 are provided and the contact of the second switch unit 102 is not properly restored. The third falling edge from the first input circuit 103 when the water intrusion detection switch 15a is in conduction (sealing failure) and the third D flip-flop 106c that outputs the failure prediction signal S10 and serves as a recovery failure detection circuit section Failure prediction signal S1 in response to detection pulse S5 (clock)
The fourth D flip-flop 106d as a seal failure detection circuit section that outputs 1 and the second falling detection pulse S6 (provided from the second input circuit 104 when the contact point of the first switch section 101 is defective) Second D as a contact failure detection circuit section that outputs a failure prediction signal S9 in response to a clock)
A failure prediction detection circuit including a flip-flop 106b. The failure prediction detection circuit 106 also includes the first and third D
O that outputs the logical sum of the outputs of the flip-flops 106a and 106c
The R circuit 106e and the output of the OR circuit 106e and the second and fourth
An OR circuit 106f that outputs a logical sum of the output from the D flip-flops 106b and 106d and an inverter 106g.

Reference numeral 107 denotes an RS flip-flop (output circuit) that outputs each output of the first input circuit 103 and the second input circuit 104 as a switch signal S12.

 Next, the operation of the switch having the above configuration will be described.

First, the normal normal mechanical operation will be described. When an object comes into contact with the operating body 4 and presses the operating body 4,
The actuation body 4 rotates to rotate the rotating rod 7 integrally against the biasing force of the coil spring 10. With the rotation of the rotating rod, the plunger in which the upper surface 12 contacts the surface of the flat portion 9
11 is pushed down, and the adjusting screw 22 portion is pushed down to the lower end portion thereof, and the movable body 18 is lowered against the biasing force of the coil spring 21. When the movable body 18 descends, the movable contacts 20 are pushed up by the displacement of the leaf springs 20a, and the movable contacts 2
0 is separated from each fixed contact 17.

Next, when the object separates from the actuating body 4, the actuating body 4 is returned by the force of the coil spring 10, the plunger 12 rises in response to the returning operation of the actuating body 4, and accordingly the coil spring
The movable body 18 also returns upward due to the 21 force, and the first switch portion 101 and then the second switch portion 102 are return-connected.
In this return operation, after the first switch portion 101 returns, the position of the pressed portion of the flat portion 9 of the rotary rod 7 by the pressing member 8 switches from the tapered surface 9a to the horizontal surface 9b, and the return load based on the coil spring 10 Although it is reduced on the way, the second switch portion 102 can be smoothly connected because there is no problem such as poor friction in the operating body 4.

(A) Circuit operation corresponding to the above normal mechanical operation [refer to FIG. 8 (a)] The first switch unit 101 receives the first input of the on / off signal S1 having a rising time t0 and a falling time t1. Circuit 103
Given to. Also, in response to this, the second switch unit 10
From 2, the on / off signal S2 having a rising time t0 and a falling time 12 is given to the second input circuit 104. Then, the first input circuit 103 outputs the first rising edge detection pulse S3 at time t0 and the first falling edge detection pulse S5 at time t1, and the second input circuit 104 outputs time t0. At the time t2, the second rising edge detection pulse S4
Then, the second falling edge detection pulse S6 is output.

The timer circuit 105 starts the timer operation by the first falling detection pulse S5 from the first input circuit 103, and resets the timer operation by the second falling detection pulse S6 from the second input circuit 104. To be made. Therefore, the timer circuit 5 does not output the time-up signal S7.

Further, the failure prediction detection circuit 106 does not output the failure prediction signal S13, and only the switch signal S12 is output from this output circuit 107 from this switch. Lights up, and the normal operation of the switch is confirmed.

(B) Circuit operation when the second switch section 102 does not return to normal due to an increase in frictional force that causes the operation body 4 to stop operating or return slowly while returning, or dust is caught in the contact portion. FIG. 8 (b)] In this case, since the second falling edge detection pulse S6 is supplied from the second input circuit 104 to the timer circuit 105 at time t4, the second input circuit 104 already outputs from the first input circuit 103. Since the timer circuit 105 whose timer operation is started by the first falling detection pulse S5 of the above has timed up at time t3 before the second falling detection pulse S6 is given, the timer circuit 105 The time-up signal S7 from the first D flip-flop 106a and the third D
It is output to each of the flip-flops 106c. Then, in this case, since the output of the second input circuit 104 given to the input section D of the third D flip-flop 106c is already at the high level at this time t3, the time-up signal S7 is given. The third D flip-flop 106c
Output becomes high level at the time t3, and the high level output (fault prediction signal S10) is output as a fault prediction signal S13 from the fault prediction detection circuit 106 via the OR circuits 106e and 106f, and this fault prediction signal S13 By the other LED40
Is lit.

Even when the above LED 40 is turned on, the output circuit 1
Since the switch signal S12 based on the operation of the first switch unit 101 from 07 is output in a predetermined state, the controlled machine continues to operate normally. The actuation body 4 or the contact portion may be repaired when the production line is stopped.

The operation stop or the delay of the return operation during the return of the operating body 4 due to the increase of the frictional force is surely generated by the return load reducing action of the tapered surface 9a in the flat portion 9 of the rotating rod 7. There is.

(C) Circuit operation when the contact point of the first switch unit 101 is defectively restored due to foreign matter biting in (see FIG. 8C). In this case, the first switch unit 101 outputs a high-level ON / OFF signal. Since S1 is continuously output, the first falling detection pulse S5 is not output from the first input circuit 103. Therefore, the timer circuit 5 cannot start the timer operation. Then, at the time t2, when the second falling detection pulse S6 (clock) is input from the second input circuit 104 to the second D flip-flop 106b,
It may be that the high level output from the first input circuit 103 is given to the input section of the second D flip-flop 106b.
An output (failure prediction signal S9) which becomes high level at time t2 is output from the output part of the second D flip-flop 106b,
The high level output is output as a failure prediction signal S13 of the failure prediction detection circuit 106 via the OR circuits 106e and 106f, and the other LED 40 is turned on by the failure prediction signal S13.

Even when the above LED 40 is turned on, the output circuit 1
Since the switch signal S12 from 07 based on the operation of the second switch unit 102 is output in a predetermined state, the controlled machine continues to operate normally.

In each of the above states (A), (B), and (C), water does not enter the casing 1, and the insulating sheet 25 is provided between the electrode plates 26.
Is maintained in a separated state with no intervening, and is not short-circuited. During use, water invades from the gap between the casings 1 and gradually accumulates, and when the electrode plates 25 are in contact with the water, a short circuit occurs between the electrode plates 25. Next, the circuit operation at that time will be described.

(D) Circuit operation when water enters the casing 1 [see FIG. 2 (d)] In this case, the output of the second input circuit 104 continues to be at a low level (liquid detection signal) at time t1. Also in the above, since the output of the second input circuit 104 is low level, the high level output is given from the inverter 106g to the input part of the fourth D flip-flop 106d. And the fourth
Since the first falling edge detection pulse S5 is applied as a clock from the first input circuit 103 to the input section D of the D flip-flop 106d, the fourth D flip-flop 106d at the time t1. A high level output (fault prediction signal S11) is output. This high level output is output to the failure prediction detection circuit 1 via the OR circuits 106e and 106f.
The error prediction signal S13 is output from 06, and the other LED (alarm mechanism) 40 is turned on by the failure prediction signal S13.

Even when water enters and the second switch section 102 is short-circuited as described above, the first switch section 101 located above operates normally and is output from the output circuit 107 based on the operation. The switch signal S12 causes the controlled device to operate normally. Then, by confirming the lighting of the other LED 40, the repair is performed when the production line is stopped. The electrode plate 25 constituting the water intrusion detection mechanism 15 is the first switch section.
Since it is provided so as to be located below 101, the electrode plates 25 short-circuit before the first switch portions 101 when water enters, so that the first switch portion 101 normally operates the controlled machine. The operation is surely prevented from sudden runaway.

[Brief description of drawings]

1 to 8 relate to an embodiment of the present invention, FIG. 1 is an exploded perspective view, FIG. 2 is a longitudinal sectional view, FIG. 3 is a front view including a partly cutaway portion, and FIG. FIG. 5 is a side view of the rod, FIG. 5 is a sectional view of the flat portion of the rotating rod, FIG. 6 is an enlarged front view of the switch mechanism portion, FIG. 7 is a circuit diagram, and each of FIG. 8 is a time chart showing the operation. is there. 1 is a casing, 4 is an actuator, 14 is a switch body, 15 is a liquid intrusion detection mechanism, and 40 is an LED.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomofumi Kurashige Tateishi Electric Co., Ltd., No. 10, Hanazono Todo-cho, Ukyo-ku, Kyoto City, Kyoto Prefecture (56) References 59-154647 (JP, U)

Claims (1)

(57) [Claims] 1. A box-shaped casing in which a through hole is provided at an appropriate position and an opening is formed in one side surface portion, and the box-shaped casing is mounted on the casing surface at a position having the through hole.
An actuating mechanism that is displaced by contact with an external object, a switch mechanism that is disposed in the casing, and operates in conjunction with the actuating mechanism through the through hole, and at least one pair of electrodes that is disposed in the casing. A liquid intrusion detection mechanism having a plate; and an alarm mechanism mounted on the casing and performing an alarm operation in response to an input of a liquid detection signal from the liquid intrusion detection mechanism, wherein the switch mechanism and the liquid intrusion detection mechanism are The casing is inserted and deployed in the casing through the opening of the casing, and the opening is closed by a lid, and the electrode plate is provided on a side surface portion facing the one side surface portion of the casing. A limit switch characterized by being arranged so as to cover the inner surface.