JPH0436516Y2 - - Google Patents

Description

[Detailed Description of the Invention] <<Technical Field of the Invention>> This invention relates to a limit switch used for object detection, etc.

<<Prior Art>> A limit switch includes a switch box housing a built-in switch and an actuator for operating the built-in switch. The lead wires inside the cable are soldered directly to the terminals of the built-in switch, and then the switch box is filled with epoxy resin to protect and insulate the internal components.

[Problem that the invention aims to solve] If the connection between the built-in switch and the cable is hardened with resin in this way, if the limit switch or built-in switch malfunctions and needs to be disconnected, the cable can be disconnected once. Must. However, if the place where the limit switch is installed is narrow and complicated, there is a problem in that such cutting and subsequent soldering and resin filling operations become extremely difficult.

SUMMARY OF THE INVENTION It is therefore an object of this invention to provide an improved limit switch that allows easy connection of a cable to a built-in switch.

<Means for Solving the Problems> The limit switch according to this invention is a limit switch comprising a switch box housing a built-in switch and an actuator protruding from the tip of the switch box for actuating the built-in switch. The switchbox has a thick wall portion juxtaposed to each other on both sides of the actuator, and a dredge portion located below the thick wall portion and covered with a cover, and has a recess formed inside the dredge portion via a protrusion. The built-in switch is accommodated in the recess, and the terminal of the built-in switch is connected to a vertical part that protrudes from the bottom of the built-in switch in a direction perpendicular to the cover, and is connected to the cover. A horizontal part extending in the horizontal direction is formed in an L-shape, a cylindrical flange part is formed in the horizontal part, and a screw is screwed into a female thread formed inside the cylindrical flange part. A crimp terminal fixed to the tip of the lead wire is screwed to the horizontal part,
A frame portion having an inclined surface on an inner surface is formed on a peripheral edge of the cover, and a seal ring is sandwiched between the inclined surface of the frame portion and the protrusion inside the dredged portion. do.

<<Example>> FIGS. 1 and 2 show an example of this invention. Reference numeral 1 designates a rectangular switch box, and an actuator, which will be described later, and which includes a movable plunger 19, a roller 20, etc., is provided protruding from the tip of the switch box 1. Further, both sides of the actuator are thick-walled parts, and both sides of the thick-walled parts are provided with mounting holes 2. On the lower side of the thick part, there is a dredged part 3 which is juxtaposed to the thick part and is slightly lower than the thick part.
and a recess 5 formed one step lower on the inside thereof with a protrusion 4 interposed therebetween. A built-in switch 6 is accommodated in the recess 5 and positioned by a pin 7 protruding from the bottom of the switch box 1.

The actuator 6a of the built-in switch 6 is inserted into the plunger mounting hole 8 provided in the thick wall of the switch box 1.
It faces an opening 10 formed in the wall 9 that partitions the recess 5, and the tip of the auxiliary plunger 11 looks into the opening 10. Auxiliary plunger 11
is slidably supported by a holder 13 fixed to the bottom of the plunger mounting hole 8 via a seal packing 12. A spring seat 14 is loosely fitted to the tip of the auxiliary plunger 11, and compression coil springs 15 and 16 are interposed between the spring seat 14 and the holder 13 and between the intermediate step of the auxiliary plunger 11, respectively. . Another holder 17 is provided at the entrance of the plunger mounting hole 8.
is fixed through the cover 18, and this holder 17
A movable plunger 19 is slidably supported on. A spring seat 14 at the tip of the auxiliary plunger 11 is engaged with a step inside the movable plunger 19, and a flange at the lowest end of the spring seat 14 is connected to a holder 17.
They are hooked onto the bottom end of the holder, and each is secured to prevent it from coming off. Further, a roller 20 is rotatably attached to the tip of the movable plunger 19. These parts constitute an actuator.

As shown in FIG. 3, each terminal 21 of the built-in switch 6 has a vertical portion 21a that projects from the bottom of the built-in switch 6 in a direction perpendicular to the cover 18, and a vertical portion 21a that is continuous with the vertical portion 21a and is horizontal to the cover 18. A horizontal portion 21b extending in the direction is L-shaped, and a downward cylindrical flange portion 21c is formed by burring on the horizontal portion 21b, and a female thread is formed inside the flange portion 21c. Such a terminal 21 is integrally insert-molded when the case of the built-in switch 6 is resin-molded. A terminal block 22 that receives the horizontal part 21b and the cylindrical flange part 21c of the terminal 21 is fixed inside the switch box 1, and the crimp terminal 23 connected to the lead wire at the tip of the cable is attached with a screw 24 to the tube of the terminal 21. It is attached to the terminal 21 by screwing into the shaped flange portion 21c. The screw hole for the screw 24 may be provided directly in the terminal block 22 or switch box 1 by forming a through hole in the terminal 21 and directly in the terminal block 22 or switch box 1 below.

The dredging part 3 of the switchbox 1 is covered with a cover 25 as shown in FIG.
is attached to the switchbox 1 by screws 26. A frame portion 25a is formed on the periphery of the cover 25, and the inner surface thereof is inclined as shown in FIG. 27 is sandwiched, and the inside of the recess 5 is sealed. The pressing force caused by tightening the screw 26 is divided by the inclined surface into a direction along the inclined surface and a direction perpendicular to the inclined surface, and presses the seal ring 27 evenly.

In addition, several such limit switches are sometimes used in stacks, and L-shaped protrusions 28 are formed on both sides of one side of the thick part of the switch box 1 for positioning when stacking. , an L-shaped groove into which the projection 28 fits is formed at a portion of the back surface corresponding to the projection 28 . In addition, in order to prevent the screw head of the screw 26 for attaching the cover 25 from getting in the way when the limit switches are stacked, the screw 26 is placed on the opposite side corresponding to the screw hole 29 for the screw 26 of the switch box 1. A recess 30 is formed that is slightly larger than the screw head.

Next, the operation of this limit switch will be explained. The roller 20 of this limit switch,
For example, when a dog attached to a belt conveyor line presses, the movable plunger 19 first presses the outer compression coil spring 15, and the expansion force of the inner compression coil spring 16 presses the auxiliary plunger 11 via the spring seat 14. Its tip presses the actuator 6a of the built-in switch 6 to turn on the switch. When the movable plunger 19 is further pressed, the spring seat 14 also presses the inner compression coil spring 16, causing the spring seat 14 to push against the auxiliary plunger 11.
This prevents the built-in switch 6 from being destroyed due to further movement of the auxiliary plunger 11. At this time, the air inside the plunger mounting hole 8 is
Escape to air chamber 31. When the dog passes the roller 20, the spring seat 14 and the movable plunger 19 return to their original positions due to the restoring forces of the compression coil springs 15 and 16, respectively, and the built-in switch 6 is deactivated. The on/off signal of the built-in switch 6 is taken out from the terminal 21 through the crimp terminal 23 and a lead wire (not shown).

[Effects of the invention] As described above, the limit switch according to this invention is formed so that the terminal of the built-in switch can be directly connected to the crimp terminal fixed to the tip of the lead wire, so it is easy to attach and replace the cable to the limit switch. This can be done extremely easily, and the limit switch can be made smaller.

Further, the terminal of the built-in switch has an L-shape consisting of a vertical part that projects from the bottom of the built-in switch in a direction perpendicular to the cover, and a horizontal part that is continuous with the vertical part and extends in the horizontal direction with respect to the cover. Since the crimp terminal fixed to the tip of the lead wire is screwed to this horizontal part, the lead wire can be connected from the opening side of the recess (cover installation side), making the lead wire connection work easier. It will become

Further, the cover to be attached to the dredged part on the switch box side has a frame part having an inclined surface on the inner surface formed on its periphery, and a seal is formed between the inclined surface of this frame part and the protrusion on the inside of the said dredged part. Since the ring is sandwiched between the rings to seal the inside of the recess on the switchbox side, the pressing force against the dredging part on the cover side is distributed in the direction along the slope and in the direction perpendicular to the slope due to the slope. The oil is dispersed and presses the seal ring evenly, improving the sealing performance within the recess, shutting out intrusion of oil and water from the outside, and preventing failures caused by such intrusion.
This will result in a longer lifespan.

[Brief explanation of drawings]

FIG. 1 is a partially sectional front view of a limit switch with the cover removed, showing an embodiment of this invention;
2 is a vertical sectional view of the limit switch shown in FIG. 1, FIG. 3 is a perspective view showing a part of the terminals of the built-in switch in the limit switch shown in FIG. 1, and FIG. 4 is a cover of the limit switch shown in FIG. 2. FIG. 3 is an enlarged cross-sectional view of a corner portion. 1... switch box, 3... dredging section, 4...
... protrusion, 6 ... built-in switch, 11 ... auxiliary plunger, 19 ... movable plunger, 20 ... roller, 21 ... terminal, 21a ... vertical part, 21b ...
...Horizontal part, 21c...Cylindrical flange part, 23...
Crimp terminal, 25...Cover, 25a...Frame, 2
6...Mounting screw, 27...Seal ring, 30...
...concavity.

Claims (1)

[Scope of utility model registration request] A switch box that houses a built-in switch,
A limit switch is provided with an actuator protruding from the tip of a switch box for operating the built-in switch, and the switch box includes a thick wall portion juxtaposed to each other on both sides of the actuator and located below the thick wall portion. and a recessed part covered with a cover, and a recessed part is provided inside the recessed part via a protrusion, and the built-in switch is accommodated in the recessed part, and the terminal of the built-in switch is connected to the The vertical part protrudes from the bottom of the built-in switch in the direction perpendicular to the cover, and the horizontal part continues from the vertical part and extends in the horizontal direction with respect to the cover, forming an L-shape, and the horizontal part has a cylindrical shape. A flange portion is formed, and a crimp terminal fixed to the tip of the lead wire is screwed to the horizontal portion by screwing a screw into a female thread formed inside the cylindrical flange portion, and a screw terminal is screwed to the periphery of the cover. A limit switch characterized in that a frame portion having an inclined surface is formed on an inner surface thereof, and a seal ring is sandwiched between the inclined surface of the frame portion and the protrusion inside the dredged portion.