JPH054660Y2 - - Google Patents

Description

[Detailed description of the invention] <<Industrial Application Field>> 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.

This limit switch is attached to a belt conveyor line, etc., and when a subject on the conveyor collides with it, the sliding plunger that constitutes the actuator depresses a push button provided on the built-in switch. The switch is configured so that the movable contact piece is displaced to perform switching. A switch on/off signal resulting from this switching is taken out to the outside through a lead wire.

[Problems to be solved by the invention] In this type of limit switch, there is not enough consideration given to regulating the amount of sliding of the sliding plunger that presses down the push button, and the push button pushes the movable contact piece inside the built-in switch. The structure is such that the sliding movement of the sliding plunger is regulated as the pressing stops. Therefore, there is a problem in that the load applied to the movable contact piece in the built-in switch is large and the life span is shortened.

Furthermore, the sliding plunger that constitutes the actuator of this type of limit switch is always exposed outside the switchbox and faces the test object, but this actuator and the built-in switch are part of one switchbox. Because the built-in switch is built in without any separation, the built-in switch is exposed through the sliding plunger to dust and oil adhering to the test object or dust and oil flying from processing machines, etc. This caused the built-in switch to malfunction and shorten its lifespan.

The purpose of this invention is to prevent unnecessary loads from being applied to the built-in switch by stopping the sliding plunger in the actuator after the push button is pressed down enough to switch the movable contact piece inside the built-in switch. The purpose of the present invention is to provide a limit switch that is free from malfunction and has a long life by protecting the built-in switch from dust and oil introduced through the sliding plunger.

《Means for solving the problem》 The limit switch according to this invention has push button 42.
A limit switch comprising a switch box 2 housing a built-in switch 3 having a built-in switch 3, and an actuator having a plunger 31 received in a plunger mounting hole 7 of the switch box 2 to operate the push button 42, the plunger 31 is slidably supported by a holder 33 fixed to the bottom of the plunger mounting hole 7 via the outer end of the seal packing 32, and
The plunger 31 is provided with a flange member 51 that comes into contact with the holder 33 and a stopper 52 that restricts the amount of sliding of the plunger 31, and the inner end of the seal packing 32 is placed between the stopper 52 and the flange member 51. It is characterized by being sandwiched.

《Example》 Figures 1 to 5 show one embodiment of the limit switch according to the present invention, in which Figure 1 is a plan view thereof, Figure 2 is a side view taken along the line - in Figure 1, and Figure 5 is a side view of the limit switch according to the present invention. 3
The figure is a cross-sectional view taken along the - line in Figure 1, and Figure 4 is a cross-sectional view of Figure 1.
FIG. 5 is a partially cutaway plan view with the cover removed, and FIG. 5 is a sectional view taken along the line - in FIG. 2.

In the figure, a limit switch 1 has a built-in switch 3 housed in a rectangular switch box 2, and is also integrally equipped with an actuator for operating a push button 42 of this built-in switch 3.
Moreover, the switching state of the built-in switch 3 is displayed by a display light emitting diode 16.

The switch box 2 has a storage recess 5 that stores the built-in switch 3 and a plunger mounting hole 7 that receives the movable plunger 6. The storage recess 5 and the movable plunger 6 are separated by a partition 8, but the plunger mounting hole A through hole 9 communicating with the storage recess 5 and the plunger mounting hole 7 is formed at a position corresponding to the axial center of the plunger 7 . The through hole 9 has a rear end portion 3 of the auxiliary plunger 31 in the plunger mounting hole 7.
1A is slidably protruded, and the push button 42 of the built-in switch 3 is housed in the storage recess 5.
is arranged at a position corresponding to the through hole 9, and the storage recess 3 is moved from the through hole 9 by sliding displacement of the auxiliary plunger 31.
The push button 42 is pressed at 1A.

This auxiliary plunger 31 has plunger mounting hole 9
It is slidably supported by a holder 33 fixed to the bottom of the housing via the outer end of a rubber seal gasket 32. Further, a spring seat 34 is loosely fitted to the front end of the auxiliary plunger 31, and compression coil springs 35 and 36 are interposed between the spring seat 34 and the holder 33 and between the intermediate step portion 31B of the auxiliary plunger 31, respectively. ing. On the auxiliary plunger 31 and at the front end of the spring seat 34, the spring seat 3
A locking ring 50 is attached to stop the holder 33 from coming out of the auxiliary plunger 31, and a flange member 51 that comes into contact with the rear part 33A of the holder 33 is attached to the rear end side.
A collar-shaped stopper 52 is fixed thereto for regulating the amount of rearward displacement of the auxiliary plunger 31, that is, the amount by which the rear end portion 31A of the auxiliary plunger 31 protrudes into the storage recess 5. As a result, the collar member 5
1 and the stopper 52 sandwich the inner end of the seal packing 32. Another holder 29 is fixed to the entrance of the plunger attachment hole 7 via a cover 28, and the movable plunger 6 is slidably supported on this holder 29. An auxiliary plunger 3 is attached to the stepped portion 6 in the movable plunger 6.
A spring seat 34 loosely fitted to the front end of the spring seat 34 is abutted and locked, and its lowermost flange portion 6B is caught on the lowermost end of the holder 29 to prevent it from coming off. In addition, the movable plunger 6
The roller 3 is connected to the tip end 6C of the roller 3 via the roller shaft 38.
7 is rotatably attached.

That is, the movable plunger 6, the plunger mounting hole 7, the holder 29, the auxiliary plunger 31,
The actuator is composed of parts such as a seal packing 32, a holder 33, a spring seat 34, compression coil springs 35 and 36, a roller 37, and a roller shaft 38.

In this actuator, when no pressing force is applied to the roller 37 from the outside, the auxiliary plunger 31 is moved together with the spring seat 34 by the urging force of the compression coil springs 35 and 36 to the front end side, and the flange portion 6B of the movable plunger 6 is moved to the holder. 28
It is kept in a displaced state until it comes into contact with the lowest end of and is positioned. That is, in this state, the rear end portion 31A of the auxiliary plunger 31 is retracted from the storage recess 5, and the movable plunger 6 is in a state that largely protrudes from the front end. Then, when a pressing force is applied to the roller 37 from the outside, the movable plunger 6 slides toward the inside of the plunger mounting hole 7, and the movable plunger 6 connects the compression coil spring 35 on the outside and the compression coil spring 35 on the inside through the spring seat 34. Press the compression coil spring 36. At this time, the inner compression coil spring 36 presses the auxiliary plunger 31 toward the rear end, and the auxiliary plunger 31 slides toward the rear end until the stopper 52 is positioned in contact with the bulkhead 8, and the rear end 31A It will be in a state of protruding into the storage recess 5. Then, the push button 42 of the built-in switch 3 is pressed down using the rear end 31A. In this push-down operation, the stopper 52 and the partition wall 8 are brought into contact and positioned, so that the push button 42 is given a substantially minimum amount of displacement to the push button that requires a contact switching operation in the built-in switch 3, The life of the built-in switch 3 is improved by reducing the addition to the members necessary for switching the contacts inside. When the movable plunger 6 is further pressed toward the rear end while the stopper 52 and the partition wall 8 are in contact with each other and positioned, the auxiliary plunger 31 and the spring seat 34 are placed in a loosely fitted relationship. Therefore, only the spring seat 34 is slidably displaced together with the movable plunger 6 toward the rear end side. Then, when the external pressing force on the roller 37 is released again,
The return force of the compression coil springs 35 and 36 causes the movable plunger 6, spring seat 34, and auxiliary plunger 31 to move toward the front end and return to the initial state.

The switch box 2 to which the actuator is attached as described above has mounting holes 10 formed on both sides of the switch box 2 that pass through the limit switch 1 from above and below in order to attach the limit switch 1 to other equipment. An L-shaped protrusion 11 is provided at a position surrounding a portion of the limit switch 1, and an L-shaped positioning recess is provided on the lower surface of the L-shaped protrusion 11 for receiving and positioning the protrusion 11 of an adjacent limit switch 1 when a plurality of limit switches 1 are stacked. 12 are formed. Furthermore, a cylindrical portion 15 and a hole 17 are provided on the rear surface of the switch box 2. A coupling nut (not shown) of an insulating pipe 14 in which external lead wires 13A, 13B, and 13C are bundled and stored is screwed into a screw formed on the outer periphery of the cylindrical portion 15. The light emitting diode 16 is inserted into the hole 17 from the inside of the storage recess 5 with its base 16A inserted into the storage recess 5.
It is stored in a state where it is in contact with the inner wall and positioned. Further, the outer side of the hole 17 is formed in a tapered shape with an inclined surface 17A that widens outward. By forming this inclined surface 17A,
By effectively reducing the amount by which the light emitting diode 16 protrudes from the rear end surface 2A of the switchbox 2, damage caused by collision with external members can be prevented, and at the same time, the irradiation area contributing to the irradiation of the light emitting diode 16 exposed to the outside can be increased. In addition, the diffused light emitted from the light emitting diode 16 is focused on the inclined surface 17A to improve the visibility of the irradiated state.

Further, the upper surface 18 of the switch box 2 in which the storage recess 5 is formed is formed to be one step lower than the upper surface of the region in which the plunger mounting hole 7 is provided. A continuous protruding wall 20 and two screw holes 21 are formed on the upper surface 18 so as to surround the opening edge of the storage recess 5, and the two screw holes 21 are located diagonally to each other. This upper surface 18 is covered with the cover 4 after the built-in switch 3 is stored in the storage recess 5. The cover 4 has a groove 22 on its inner surface that corresponds to the protruding wall 20 of the switchbox 2.
is formed. Further, one side wall surface within this groove 22 is formed as an inclined surface 23, and this inclined surface 2
3 and the protruding wall 20 on the upper surface 18 side, a rubber seal ring 24 is sandwiched, and the other side wall 25 of the groove 22 is in contact with the inner wall 26 of the storage recess 5, so that the cover 4 is It will be sealed. The cover 4 attached to the top surface 18 in this way is
A screw 2 is screwed into the screw hole 21 through a mounting hole formed corresponding to the two screw holes 21 formed in the
The pressing force due to the tightening of step 7 is distributed by the inclined surface 23 in a direction along the inclined surface 23 and in a direction perpendicular to the inclined surface 23, and evenly presses the seal ring 24 to prevent water from entering from the outside. . In addition, in this structure, since the other side wall 25 of the cover 4 comes into contact with the inner wall 26 of the storage recess 5 and is sealed, the screws 27 are simply tightened into the two screw holes 21. Also, since the other diagonal corners where screws are not tightened are prevented from lifting due to the contact between the other side wall 25 and the inner wall 26 of the storage recess 5, the seal ring 24 is secured over the entire recessed groove 22. This means that the screws are pressed evenly, creating a stronger seal with less screw tightening, and the structure aims to reduce the number of man-hours required for screw tightening work.

In the above embodiment, a light emitting diode was used as the light emitting element, but this does not preclude the use of an incandescent lamp, and the mounting position is not limited to the rear end surface, but can be mounted at any position as necessary. You may choose a location.

<<Effects of the invention>> As described above, the limit switch according to this invention has a stopper 52 that regulates the sliding amount of the slideable plunger 31 in the actuator that operates the push button 42 that operates the built-in switch 3.
Since this is provided, unnecessary loads applied to the movable contact piece in the built-in switch 3 can be eliminated, and the life of the built-in switch can be improved.

Further, a seal packing 32 exists between the plunger mounting hole 7 in the switch box and the accommodation recess of the built-in switch 3.
The inner and outer ends of the switch 2 are sandwiched between the bottom of the plunger mounting hole 7, the holder 33, the collar member 51, and the stopper 52, respectively, and the plunger mounting hole 7 and the accommodation recess 5 of the built-in switch 3 are connected to the seal packing 32. Therefore, it is blocked,
In particular, the seal packing 32 blocks dust, oil, etc. from entering the plunger mounting hole 7 from the subject, etc., and prevents them from entering the storage recess 5. As a result, the built-in switch housed in the storage recess 5 is protected from dust, oil, etc. entering from the outside, preventing malfunctions, and extending its life. .

Further, the seal packing 32 does not require any separate parts to fix it, and the holder 33 that slidably supports the plunger 31 and the plunger 31
Since the stopper 52, etc. that regulates the amount of sliding can be used as is for fixation, there is no need to increase the number of parts.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of a limit switch according to the present invention, and FIG.
3 is a cross-sectional view taken along the line - in FIG. 1, and FIG. 4 is a side view taken from the line shown in FIG.
Also, a partially cutaway plan view, FIG. 5 is a partially cutaway plan view.
It is a cross-sectional view taken along the line - in the figure. 2...Switch box, 3...Built-in switch, 7...Plunger mounting hole, 31...Auxiliary plunger (plunger), 32...Seal packing,
33... Holder, 42... Push button, 51... Flange member, 52... Stopper.

Claims (1)

[Scope of utility model registration request] A switch box 2 houses a built-in switch 3 having a push button 42, and the push button 4 is received in the plunger mounting hole 7 of the switch box 2.
A limit switch comprising: an actuator having a plunger 31 for operating the limit switch;
The plunger 31 is slidably supported by a holder 33 fixed to the bottom of the plunger mounting hole 7 via the outer end of a seal packing 32, and a flange member 51 that abuts the holder 33 is attached to the plunger 31. and the plunger 3
A stopper 52 for regulating the sliding amount of 1 is provided,
A limit switch characterized in that the inner end of the seal packing 32 is sandwiched between the stopper 52 and the flange member 51.